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+The Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Insects and Diseases
+       A Popular Account of the Way in Which Insects may Spread
+       or Cause some of our Common Diseases
+
+Author: Rennie W. Doane
+
+Release Date: February 24, 2009 [EBook #28177]
+Last updated: March 2, 2009
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK INSECTS AND DISEASES ***
+
+
+
+
+Produced by Chris Curnow, Lindy Walsh, Greg Bergquist and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+  Transcriber's Note
+
+  The punctuation and spelling from the original text have been faithfully
+  preserved. Only obvious typographical errors have been corrected.
+
+
+[Illustration: An artificial lake, nearly dry and partly filled with
+rubbish, has become a breeding-ground for dangerous mosquitoes.]
+
+
+
+
+ American Nature Series
+
+ Group IV. Working with Nature
+
+
+ INSECTS AND DISEASE
+
+ A POPULAR ACCOUNT OF THE WAY IN WHICH
+ INSECTS MAY SPREAD OR CAUSE SOME
+ OF OUR COMMON DISEASES
+
+ WITH MANY ORIGINAL ILLUSTRATIONS FROM
+ PHOTOGRAPHS
+
+
+ BY
+
+ RENNIE W. DOANE, A.B.
+
+ _Assistant Professor of Entomology
+ Leland Stanford Junior University_
+
+
+ LONDON
+
+ CONSTABLE & COMPANY LIMITED
+
+ 1910
+
+ COPYRIGHT, 1910,
+
+ BY
+
+ HENRY HOLT AND COMPANY
+
+
+ _Published August, 1910_
+
+
+ THE QUINN & BODEN CO. PRESS
+
+ RAHWAY, N.J.
+
+
+
+
+PREFACE
+
+
+The subject of preventive medicine is one that is attracting world-wide
+attention to-day. We can hardly pick up a newspaper or magazine without
+seeing the subject discussed in some of its phases, and during the last
+few years several books have appeared devoted wholly or in part to the
+ways of preventing rather than curing many of our ills.
+
+Looking over the titles of these articles and books the reader will at
+once be impressed with the importance that is being given to the subject
+of the relation of insects to some of our common diseases. As many of
+these maladies are caused by minute parasites or microbes the
+zoölogists, biologists and physicians are studying with untiring zeal to
+learn what they can in regard to the development and habits of these
+organisms, and the entomologists are doing their part by studying in
+minute detail the structure and life-history of the insects that are
+concerned. Thus many important facts are being learned, many important
+observations made. The results of the best of these investigations are
+always published in technical magazines or papers that are usually
+accessible only to the specialist.
+
+This little book is an attempt to bring together and place in
+untechnical form the most important of these facts gathered from sources
+many of which are at present inaccessible to the general reader, perhaps
+even to many physicians and entomologists.
+
+In order that the reader who is not a specialist in medicine or
+entomology may more readily understand the intimate biological relations
+of the animals and parasites to be discussed it seems desirable to call
+attention first to their systematic relations and to review some of the
+important general facts in regard to their structure and life-history.
+This, it is believed, will make even the most complex special
+interrelations of some of these organisms readily understandable by all.
+Those who are already more or less familiar with these things may find
+the bibliography of use for more extended reading.
+
+My thanks are due to Prof. V.L. Kellogg for reading the manuscript and
+offering helpful suggestions and criticisms.
+
+Unless otherwise credited the pictures are from photographs taken by the
+author in the laboratory and field. As many of these are pictures of
+live specimens it is believed that they will be of interest as showing
+the insects, not as we think they should be, but as they actually are.
+Mr. J.H. Paine has given me valuable aid in preparing these photographs.
+
+ R.W.D.
+
+ Stanford University, California,
+
+ March, 1910.
+
+
+
+
+CONTENTS
+
+CHAPTER I
+                                                        PAGE
+
+PARASITISM AND DISEASE                                     1
+
+Definition of a parasite, 1; examples among various animals,
+2; _Parasitism_, 3; effect on the parasite, 4; how a harmless
+kind may become harmful, 5; immunity, 6; _Diseases caused by
+parasites_, 7; ancient and modern views, 7; _Infectious and contagious
+diseases_, 8; examples, 9; importance of distinguishing,
+9; _Effect of the parasite on the host_, 9; microbes everywhere, 10;
+importance of size, 11; numbers, 11; location, 11; mechanical
+injury, 12; morphological injury, 13; physiological effect, 13;
+the point of view, 14.
+
+
+CHAPTER II
+
+BACTERIA AND PROTOZOA                                     15
+
+_Bacteria_, 15; border line between plants and animals, 15;
+most bacteria not harmful, 15; a few cause disease, 15; how
+they multiply, 15; parasitic and non-parasitic kinds, 17; how a
+kind normally harmless may become harmful, 18; effect of the
+bacteria on the host, 18; methods of dissemination, 18; _Protozoa_,
+19; _Amoeba_, 19; its lack of special organs, 19; where
+it lives, 19; growth and reproduction, 19; _Classes of Protozoa_,
+20; the amoeba-like forms, 20; the flagellate forms, 20; importance
+of these, 21; the ciliated forms, 22; the Sporozoa or spore-forming kinds,
+22; these most important, 23; abundance, 23; adaptability, 23; common
+characters, 24; ability to resist unfavorable conditions, 24.
+
+
+CHAPTER III
+
+TICKS AND MITES                                           26
+
+_Ticks_, 26; general characters, 27; mouth-parts, 27; habits,
+27; life-history, 27; _Ticks and disease_, 28; _Texas fever_, 28; its
+occurrence in the north, 28; carried by a tick, 29; loss and
+methods of control, 31; other diseases of cattle carried by ticks,
+31; _Rocky Mountain spotted fever_, 32; its occurrence, 32;
+probably caused by parasites, 32; relation of ticks to this disease,
+33; _Relapsing Fever_, 33; its occurrence, 34; transmitted
+by ticks, 34; _Mites_, 35; _Face-mites_, 35; _Itch-mites_, 36;
+_Harvest-mites_, 37.
+
+
+CHAPTER IV
+
+HOW INSECTS CAUSE OR CARRY DISEASE                        40
+
+Numbers, 40; importance, 41; losses caused by insects, 41;
+loss of life, 42; _The flies_, 43; horse-flies, 43; stable-flies, 44;
+surra, 45; nagana, 45; black-flies, 46; punkies, 46; screw-worm
+flies, 47; blow-flies, 48; flesh-flies, 48; fly larvæ in intestinal
+canal, 49; bot-flies, 50; _Fleas_, 52; jigger-flea, 53; _Bedbugs_, 54;
+_Lice_, 54; _How insects may carry disease_, 55; in a mechanical
+way, 55; as one of the necessary hosts of the parasite, 56.
+
+
+CHAPTER V
+
+HOUSE-FLIES OR TYPHOID-FLIES                              57
+
+The old attitude toward the house-fly, 57; its present standing,
+58; reasons for the change, 58; _Structure_, 59; head and
+mouth-parts, 60; thorax and wings, 61; feet, 62; _How they
+carry bacteria_, 62; _Life-history_, 63; eggs, 63; ordinarily laid in
+manure, 63; other places, 63; habits of the larvæ, 64; habits of
+the adults, 64; places they visit, 65; _Flies and typhoid_, 65;
+patients carrying the germs before and after they have had the
+disease, 65; how the flies get these on their body and distribute
+them, 66; results of some observations and experiments, 66;
+_Flies and other diseases_, 68; flies and cholera, 68; flies and
+tuberculosis, 69; possibility of their carrying other diseases, 70;
+_Fighting flies_, 71; screens not sufficient, 71; the larger problem,
+71; the manure pile, 72; outdoor privies, 72; garbage can,
+72; coöperation necessary, 72; city ordinances, 73; an expert's
+opinion of the house-fly, 73; _Other flies_, 75; habits of several
+much the same but do not enter house as much, 75; the small
+house-fly, 75; stable-flies, 75; these may spread disease, 75.
+
+
+CHAPTER VI
+
+MOSQUITOES                                                76
+
+Numbers, 76; interest and importance, 76; eggs, 77; always in water, 77;
+time of hatching, 77; _Larvæ_, 78; live only in water, 78; head and
+mouth-parts of larvæ, 78; what they feed on, 78; breathing apparatus,
+79; growth of the larvæ, 80; _Pupæ_, 80; active but takes no food, 80;
+breathing tubes, 80; how the adult issues, 81; _The Adult_, 81; male and
+female, 81; how mosquitoes "sing" and how the song is heard, 82; the
+palpi, 82; _The Mouth-parts_, 83; needles for piercing, 83; _How the
+mosquito bites_, 84; secretion from the salivary gland, 84; why males
+cannot bite, 84; blood not necessary for either sex, 84; _The Thorax_,
+85; the legs, 85; the wings, 85; the balancers, 85; the breathing pores,
+86; _The abdomen_, 86; _The digestive system_, 86; _The salivary
+glands_, 87; their importance, 87; effects of a mosquito bite, 87;
+probable function of the saliva, 88; _How mosquitoes breathe_, 89;
+_Blood_, 90; in body cavity, 90; heart, 90; _Classification_, 91;
+_Anopheles_, 91; distinguishing characters, 92; eggs, 92; where the
+larvæ are found, 93; _Yellow fever mosquito_, 94; its importance, 94;
+the adult, 95; habits, 95; habits of the larvæ, 95; _Other species_, 96;
+some in fresh water, others in brackish water, 96; Natural enemies of
+mosquitoes, 97; how natural enemies of mosquitoes control their numbers,
+98; mosquitoes in Hawaii, 98; _Enemies of the adults_, 99; _Enemies of
+the larvæ and pupæ_, 100; _Fighting mosquitoes_, 101; fighting the
+adult, 102; _Fighting the larvæ_, 103; domestic or local species, 104;
+draining and treating with oil, 104; combatting salt-marsh species by
+draining, 105; by minnows or oil, 105.
+
+
+CHAPTER VII
+
+MOSQUITOES AND MALARIA                                   106
+
+Early reference to malaria, 106; its general distribution, 106;
+theories in regard to its cause, 107; insects early suspected, 107;
+_The parasite that causes malaria_, 108; studies of the parasite,
+108; _Life-history in human host_, 109; its effect on the host, 110;
+the search for the sexual generation, 111; _The parasite in the
+mosquito_, 112; review of whole life-history, 115; malaria transmitted
+only by mosquitoes, 115; _Summary_, 117; experimental proof, 118.
+
+
+CHAPTER VIII
+
+MOSQUITOES AND YELLOW FEVER                              120
+
+A disease of tropical or semi-tropical countries, 120; outbreaks in the
+United States, 120; parasite that causes the disease not known, 121;
+formerly regarded as a contagious disease, 122; _The yellow fever
+commission_, 123; Dr. Finlay's claim, 124; experiments made by the
+commission, 125; summary of results, 129; what it means, 130; _results
+in Havana_, 131; _the fight in New Orleans_, 132; _In the Panama canal
+zone_, 135; _in Rio de Janeiro_, 136; claims of the French commission,
+138; _habits of stegomyia_, 139; breeding habits, 139; possible results
+of war against the mosquitoes, 139; Danger of this disease in the
+Pacific Islands, 140.
+
+
+CHAPTER IX
+
+FLEAS AND PLAGUE                                         142
+
+Great scourges, 142; the "black death," 142; old conditions
+and new, 143; _How plague was controlled in San Francisco_,
+143; _Indian Plague commission_, 144; Dr. Simond's claim,
+145; The advisory committee and the new commission, 146;
+_Results of Dr. Verjbitski's experiments_, 147; _Results of various
+investigations_, 150; _structure and habits of fleas_, 151; feeding
+habits, 152; _Common species of fleas_, 153; _Ground squirrels and
+plague_, 155; squirrel fleas, 156; _Remedies for fleas_, 157; cats
+and dogs, 159.
+
+
+CHAPTER X
+
+OTHER DISEASES, MOSTLY TROPICAL, KNOWN OR THOUGHT TO
+BE TRANSMITTED BY INSECTS                                161
+
+_Sleeping Sickness_, 161; its occurrence in Africa, 161; caused by a
+Protozoan parasite, 162; the tsetse-fly, 163; _Elephantiasis_, 164;
+caused by parasitic worms, 164; their development, 165; how they are
+transferred to man, 165; effect on the patient, 166; _Dengue_, 168;
+other names, 168; probably transmitted by mosquitoes, 170;
+_Mediterranean fever_, 171; cause, 171; may be conveyed by mosquitoes,
+171; _Leprosy_, 171; caused by a bacteria parasite, 171; possibilities
+of flies, mosquitoes and other insects transmitting the disease, 172;
+_Kala-azar_, 173; transmitted by the bedbug, 173; _Oriental sore_, 174;
+the parasite may be carried by insects, 174.
+
+BIBLIOGRAPHY                                             175
+
+Parasites and parasitism, 175; Protozoa, 176; Bacteria, 177; Insects and
+disease, 178; Mosquitoes--systematic and general, 179; Mosquito anatomy,
+182; Mosquitoes--life-history and habits, 183; Mosquito fighting, 183;
+Mosquitoes and disease, 185; Malaria, 186; Yellow fever, 189; Dengue,
+192; Filarial diseases and elephantiasis, 193; Leprosy, 193; Plague,
+194; Fleas, 198; Typhoid fever, 199; House-flies--anatomy, life-history,
+habits, 200; House-flies and typhoid, 202; House-fly and various
+diseases, 203; Human myiasis, 207; Stomoxys and other flies, 208;
+tsetse-flies, 209; Trypanosomes and Trypanosomiasis, 210; Sleeping
+sickness, 211; Rocky mountain fever and ticks, 212; Ticks and various
+diseases, 213; Kala-azar and bedbugs, 216; Text or reference books, 216;
+Miscellaneous articles, 218.
+
+
+
+
+ILLUSTRATIONS
+
+ AN ARTIFICIAL LAKE, NEARLY DRY AND PARTLY
+ FILLED WITH RUBBISH, HAS BECOME A BREEDING-GROUND
+ FOR DANGEROUS MOSQUITOES                                 _Frontispiece_
+
+                                                                    PAGE
+
+ FIG. 1. A LAMPREY                                                     2
+
+ FIG. 2. _Sacculina_                                                   2
+
+ FIG. 3. _Trichina spiralis_                                           2
+
+ FIG. 4. AN EXTERNAL PARASITE, A BIRD-LOUSE (_Lipeurus
+   ferox_)                                                             3
+
+ FIG. 5. AN INTERNAL PARASITE, A TACHINA FLY (_Blepharipeza
+   adusta_)                                                            3
+
+ FIG. 6. WORK OF AN INTERNAL PARASITE, PUSS-MOTH LARVA
+   PARASITIZED BY A SMALL ICHNEUMON FLY                                3
+
+ FIG. 7. TYPHOID FEVER BACILLI                                        20
+
+ FIG. 8. _Amoeba_                                                     20
+
+ FIG. 9. _Euglina virdis_                                             21
+
+ FIG. 10. _Spirocheta duttoni_                                        21
+
+ FIG. 11. _Paramoecium_                                               22
+
+ FIG. 12. _Vorticella_                                                22
+
+ FIG. 13. PATHOGENIC PROTOZOA; A GROUP OF INTESTINAL
+   PARASITES                                                          22
+
+ FIG. 14. CASTOR-BEAN TICK (_Ixodes ricinus_)                         28
+
+ FIG. 15. TEXAS FEVER TICK                                            28
+
+ FIG. 16. TEXAS FEVER TICK (_Margaropus annulatus_)                   29
+
+ FIG. 17. _Amblyomma variegatum_                                      29
+
+ FIG. 18. _Ornithodoros moubata_                                      36
+
+ FIG. 19. THE FOLLICLE MITE (_Demodex folliculorum_)                  36
+
+ FIG. 20. ITCH-MITE (_Sarcoptes scabiei_)                             37
+
+ FIG. 21. HARVEST-MITES OR "JIGGERS"                                  37
+
+ FIG. 22. HORSE-FLY (_Tabanus punctifer_)                             44
+
+ FIG. 23. STABLE-FLY (_Stomoxys calcitrans_)                          44
+
+ FIG. 24. A BLACK-FLY (_Simulium sp._)                                45
+
+ FIG. 25. SCREW-WORM FLY (_Chrysomyia macellaria_)                    45
+
+ FIG. 26. BLOW-FLY (_Calliphora vomitoria_)                           45
+
+ FIG. 27. BLUE-BOTTLE FLY (_Lucilia sericata_)                        50
+
+ FIG. 28. FLESH-FLY (_Sarcophaga sp._)                                50
+
+ FIG. 29. "THE LITTLE HOUSE-FLY" (_Homalomyia canicularis_)           51
+
+ FIG. 30. HORSE BOT-FLY (_Gastrophilus equi._)                        51
+
+ FIG. 31. OXWARBLE FLY (_Hypoderma lineata_)                          51
+
+ FIG. 32. SHEEP BOT-FLY (_Gastrophilus nasalis_)                      51
+
+ FIG. 33. CHIGO OR JIGGER-FLEA, MALE (_Dermatophilus penetrans_)      54
+
+ FIG. 34. CHIGO, FEMALE DISTENDED WITH EGGS                           54
+
+ FIG. 35. BEDBUG (_Cimex lectularis_)                                 55
+
+ FIG. 36. BODY-LOUSE (_Pediculus vestimenti_)                         55
+
+ FIG. 37. ONE USE FOR THE HOUSE-FLY                                   57
+
+ FIG. 38. THE HOUSE-FLY (_Musca domestica_)                           58
+
+ FIG. 39. HEAD OF HOUSE-FLY SHOWING EYES, ANTENNÆ AND
+   MOUTH-PARTS                                                        60
+
+ FIG. 40. PROBOSCIS OF HOUSE-FLY, SIDE VIEW                           60
+
+ FIG. 41. LOBES AT END OF PROBOSCIS OF HOUSE-FLY SHOWING
+   CORRUGATED RIDGES                                                  61
+
+ FIG. 42. WING OF HOUSE-FLY                                           61
+
+ FIG. 43. WING OF STABLE-FLY (_Stomoxys calcitrans_)                  62
+
+ FIG. 44. WING OF HOUSE-FLY SHOWING PARTICLES OF DIRT
+   ADHERING TO IT                                                     62
+
+ FIG. 45. LAST THREE SEGMENTS OF LEG OF HOUSE-FLY                     62
+
+ FIG. 46. FOOT OF HOUSE-FLY                                           63
+
+ FIG. 47. LARVA OF HOUSE-FLY                                          63
+
+ FIG. 48. BARN-YARD FILLED WITH MANURE                                64
+
+ FIG. 49. DIRTY STALLS                                                65
+
+ FIG. 50. PUPA OF HOUSE-FLY                                           76
+
+ FIG. 51. HEAD OF STABLE-FLY                                          76
+
+ FIG. 52. MASS OF MOSQUITO EGGS (_Theobaldia incidens_)               76
+
+ FIG. 53. MOSQUITO EGGS AND LARVÆ (_T. incidens_)                     77
+
+ FIG. 54. MOSQUITO LARVA (_T. incidens_), DORSAL VIEW                 77
+
+ FIG. 55. EGGS, LARVÆ AND PUPÆ OF MOSQUITOES (_T. incidens_)          78
+
+ FIG. 56. LARVA OF MOSQUITO (_T. incidens_)                           78
+
+ FIG. 57. MOSQUITO LARVÆ AND PUPÆ (_T. incidens_)                     79
+
+ FIG. 58. ANOPHELES LARVÆ (_A. maculipennis_)                         79
+
+ FIG. 59. MOSQUITO PUPÆ (_T. incidens_)                               80
+
+ FIG. 60. MOSQUITO PUPA (_T. incidens_)                               80
+
+ FIG. 61. MOSQUITO LARVÆ AND PUPÆ (_T. incidens_)                     80
+
+ FIG. 62. A FEMALE MOSQUITO (_T. incidens_)                           81
+
+ FIG. 63. A MALE MOSQUITO (_T. incidens_)                             81
+
+ FIG. 64. HEAD AND THORAX OF FEMALE MOSQUITO (_Ochlerotatus
+   lativittatus_)                                                     82
+
+ FIG. 65. HEAD AND THORAX OF MALE MOSQUITO (_O. lativittatus_)        82
+
+ FIG. 66. HEAD OF FEMALE MOSQUITO                                     83
+
+ FIG. 67. CROSS-SECTION OF PROBOSCIS OF FEMALE AND MALE
+   MOSQUITO                                                           83
+
+ FIG. 68. WING OF MOSQUITO (_O. lativittatus_)                        86
+
+ FIG. 69. END OF MOSQUITO WING HIGHLY MAGNIFIED                       86
+
+ FIG. 70. DIAGRAM TO SHOW THE ALIMENTARY CANAL AND
+   SALIVARY GLANDS OF A MOSQUITO                                      87
+
+ FIG. 71. SALIVARY GLANDS OF MOSQUITOES                               87
+
+ FIG. 72. HEADS OF CULICINÆ MOSQUITOES                                90
+
+ FIG. 73. HEADS OF ANOPHELINÆ MOSQUITOES                              90
+
+ FIG. 74. WING OF _Anopheles maculipennis_                            90
+
+ FIG. 75. WING OF _Theobaldia incidens_                               90
+
+ FIG. 76. A NON-MALARIAL MOSQUITO (_T. Incidens_), MALE,
+   STANDING ON THE WALL                                               91
+
+ FIG. 77. FEMALE OF SAME                                              91
+
+ FIG. 78. A MALARIAL MOSQUITO (_A. maculipennis_), MALE,
+   STANDING ON THE WALL                                               91
+
+ FIG. 79. FEMALE OF SAME                                              91
+
+ FIG. 80. EGG OF _Anopheles_, SIDE VIEW                               92
+
+ FIG. 81. EGG OF ANOPHELES, DORSAL VIEW                               92
+
+ FIG. 82. ANOPHELES LARVÆ                                             92
+
+ FIG. 83. ANOPHELES LARVÆ                                             93
+
+ FIG. 84. ANOPHELES LARVA, DORSAL VIEW                                93
+
+ FIG. 85. ANOPHELES PUPÆ RESTING AT SURFACE OF WATER                  93
+
+ FIG. 86. SALT-MARSH MOSQUITO (_Ochlerotatus lativittatus_);
+   MALE                                                               98
+
+ FIG. 87. SALT-MARSH MOSQUITO (_O. lativittatus_); FEMALE             98
+
+ FIG. 88. TOP-MINNOW (_Mollienisia latipinna_)                        99
+
+ FIG. 89. DRAGON-FLIES                                                99
+
+ FIG. 90. THE YOUNG (NYMPH) OF A DRAGON-FLY                          100
+
+ FIG. 91. THE CAST SKIN (_exuvæ_) OF A DRAGON-FLY NYMPH              100
+
+ FIG. 92. DIVING-BEETLES AND BACK-SWIMMERS                           101
+
+ FIG. 93. KILLIFISH (_Fundulus heteroliatus_)                        102
+
+ FIG. 94. STICKLEBACK (_Apeltes quadracus_)                          102
+
+ FIG. 95. AN OLD WATERING-TROUGH, AN EXCELLENT BREEDING-PLACE
+   FOR MOSQUITOES                                                    103
+
+ FIG. 96. HORSE AND CATTLE TRACKS IN MUD FILLED WITH
+   WATER                                                             108
+
+ FIG. 97. A MALARIAL MOSQUITO (_Anopheles maculipennis_)
+   MALE                                                              108
+
+ FIG. 98. A MALARIAL MOSQUITO (_A. maculipennis_) FEMALE             109
+
+ FIG. 99. DIAGRAM TO ILLUSTRATE THE LIFE-HISTORY OF THE
+   MALARIAL PARASITE                                                 110
+
+ FIG. 100. MALARIAL MOSQUITO (_A. maculipennis_) ON THE WALL         111
+
+ FIG. 101. MALARIAL MOSQUITO (_A. maculipennis_) STANDING ON
+   A TABLE                                                           111
+
+ FIG. 102. SALT-MARSH MOSQUITO (_O. lativittatus_) STANDING ON
+   A TABLE                                                           118
+
+ FIG. 103. ANOPHELES HANGING FROM THE CEILING                        118
+
+ FIG. 104. YELLOW FEVER MOSQUITO (_Stegomyia calopus_)               122
+
+ FIG. 105. RAT-FLEA (_Læmopsylla cheopis_); MALE                     152
+
+ FIG. 106. RAT-FLEA (_L. cheopis_); FEMALE                           152
+
+ FIG. 107. HEAD OF RAT-FLEA SHOWING MOUTH-PARTS                      153
+
+ FIG. 108. HUMAN-FLEA (_Pulex irritans_); MALE                       153
+
+ FIG. 109. HUMAN-FLEA (_P. irritans_); FEMALE                        156
+
+ FIG. 110. MOUSE-FLEA (_Ctenopsyllus musculi_); FEMALE               156
+
+ FIG. 111. TRYPANOSOMA GAMBIENSE                                     164
+
+ FIG. 112. TSETSE-FLY                                                164
+
+
+
+
+INSECTS AND DISEASE
+
+
+
+
+CHAPTER I
+
+PARASITISM AND DISEASE
+
+
+PARASITES
+
+The dictionary says that a parasite is a living organism, either animal
+or plant, that lives in or on some other organism from which it derives
+its nourishment for a whole or part of its existence. This definition
+will serve as well as any, as it seems to include all the forms that
+might be classed as parasites. As a general thing, however, we are
+accustomed to think of a parasite as working more or less injury to its
+host, or perhaps we had better say that if it does not cause any
+irritation or ill effects its presence is not noted and we do not think
+of it at all.
+
+As a matter of fact the number of parasitic organisms that are actually
+detrimental to the welfare of their hosts is comparatively small while
+the number of forms both large and small that lead parasitic lives in
+or on various hosts, usually doing no appreciable harm, often perhaps
+without the host being aware of their presence, is very great indeed.
+
+Few of the higher animals live parasitic lives. The nearest approach to
+a true parasite among the vertebrates is the lamprey-eel (Fig. 1) which
+attaches itself to the body of a fish and sucks the blood or eats the
+flesh. Among the Crustaceans, the group that includes the lobsters and
+crabs, we find many examples of parasites, the most extraordinary of
+which is the curious crab known as _Sacculina_ (Fig. 2). In its early
+stages this creature is free-swimming and looks not unlike other young
+crabs. But it soon attaches itself to another crab and begins to live at
+the expense of its host. Then it commences to undergo remarkable changes
+and finally becomes a mere sac-like organ with a number of long slender
+root-like processes penetrating and taking nourishment from the body of
+the unfortunate crab-host.
+
+The worms furnish many well-known examples of parasites, whole groups of
+them being especially adapted to parasitic life. The tapeworms, common
+in many animals and often occurring in man, the roundworms of which the
+trichina (Fig. 3) that causes "measly" pork is a representative, are
+familiar examples. These and a host of others all show a very high
+degree of specialization fitting them for their peculiar lives in their
+hosts.
+
+[Illustration: FIG. 1--A lamprey. (After Goode.)]
+
+[Illustration: FIG. 2--_Sacculina_; _A_, parasite attached to a crab;
+_B_, the active larval condition; _C_, the adult removed from its host.
+(After Haeckel.)]
+
+[Illustration: FIG. 3--_Trichina spiralis_ encysted in muscle of a pig.
+(From Kellogg's Elementary Zoöl.)]
+
+[Illustration: FIG. 4--An external parasite, a bird-louse (_Lipeurus
+ferox_).]
+
+[Illustration: FIG. 5--A tachina fly (_Blepharipeza adusta_) the larva
+of which is an internal parasite.]
+
+[Illustration: FIG. 6--Work of an internal parasite, puss-moth larva
+parasitized by a small ichneumon fly.]
+
+From among the insects may be selected interesting examples of almost
+all kinds and degrees of parasitism, temporary, permanent, external,
+internal (Figs. 4, 5, 6). Among them is found, too, that curious
+condition known as hyperparasitism where one animal, itself a parasite,
+is preyed upon by a still smaller parasite.
+
+  "The larger fleas have smaller fleas
+  Upon their backs to bite um,
+  These little fleas still smaller fleas
+  And so _ad infinitum_."
+
+Coming now to the minute, microscopic, one-celled animals, the Protozoa,
+we find entire groups of them that are living parasitic lives, depending
+wholly on one or more hosts for their existence. Many of these have a
+very remarkable life-history, living part of the time in one host, part
+in another. The malarial parasite and others that cause some of the
+diseases of man and domestic animals are among the most important of
+these.
+
+
+PARASITISM
+
+Among all these parasites, from the highest to the lowest the process
+that has fitted them for a parasitic life has been one of degeneration.
+While they may be specialized to an extreme degree in one direction they
+are usually found to have some of the parts or organs, which in closely
+related forms are well developed, atrophied or entirely wanting. As a
+rule this is a distinct advantage rather than a disadvantage to the
+parasite, for those parts or organs that are lost would be useless or
+even in the way in its special mode of life.
+
+Then, too, the parasite often gives up all its independence and becomes
+wholly dependent on its host or hosts not only for its food but for its
+dissemination from one animal to another, in order that the species may
+not perish with the host. But in return for all this it has gained a
+life of ease, free from most of the dangers that beset the more
+independent animals, and is thus able to devote its whole time and
+energy to development and the propagation of the species.
+
+We are accustomed to group the parasites that we know into two classes,
+as harmful or injurious and as harmless, the latter including all those
+kinds that do not ordinarily affect our well-being in any way. But such
+a classification is not always satisfactory or safe, for certain
+organisms that to-day or under present conditions are not harmful may,
+on account of a great increase in numbers or change of conditions,
+become of prime importance to-morrow. An animal that is well and strong
+may harbor large numbers of parasites which are living at the expense of
+some of the host's food or energy or comfort, yet the loss is so small
+that it is not noticed and the intruders, if they are thought of at all,
+are classed as harmless. Or we may at times even look upon them as
+beneficial in one way or another. "A reasonable amount of fleas is good
+for a dog. They keep him from brooding on being a dog."
+
+But should these parasites for some reason or other increase rapidly
+they might work great harm to the host. Even David Harum would limit the
+number of fleas on a dog. Or the animal might become weakened from some
+cause so that the drain on its resources made by the parasites, even
+though they did not increase in numbers, would materially affect it.
+
+Perhaps the most serious way in which parasites that are usually
+harmless may become of great importance is illustrated by their
+introduction into new regions or, as is more often the case, by the
+introduction of new hosts into the region where the parasites are found.
+Under normal conditions the animals of a given region are usually immune
+to the parasites of the same region. That is, they actually repel them
+and do not suffer them to exist in or on their bodies, or they are
+tolerant toward them. In the latter case the parasites live at the
+expense of the host, but the host has become used to their being there,
+adapted to them, and the injury that they do, if any, is negligible.
+
+But when a new animal comes into the region from some other locality the
+parasites may be extremely dangerous to it. There are many striking
+examples of this. Most of the people living in what is known as the
+yellow fever belt are immune to the fever. They will not develop it even
+under conditions that would surely mean infection for a person from
+outside this zone. Certain of our common diseases which we regard as of
+little consequence become very serious matters when introduced among a
+people that has never known them before. The cattle of the southern
+states are immune to the Texas fever, but let northern cattle be sent
+south or let the ticks which transmit the disease be taken north where
+they can get on cattle there, and the results are disastrous.
+
+Another striking example and one that is attracting world-wide attention
+just now is the trypanosome that is causing such devastation among the
+inhabitants of central Africa. With the advent of white men into this
+region and the consequent migration of the natives along the trade
+routes this parasite, which is the cause of sleeping sickness, is being
+introduced into new regions and thousands upon thousands of people are
+dying as a result of its ravages.
+
+
+DISEASES CAUSED BY PARASITES
+
+Some two hundred years ago, after it became known that minute animal
+parasites were associated with certain diseases and were the cause of
+them, it rapidly came to be believed that all our ills were in some way
+caused by such parasites, known or unknown. Further study and
+investigation failed to reveal the intruders in many instances and so it
+began to be doubted whether after all they were responsible for much
+that had been laid at their doors. Then after it was discovered that
+minute plant parasites, bacteria, were responsible for many diseases
+they in turn began to be accused of being the cause of most of the ills
+that the flesh is heir to.
+
+In later years we have come to adopt what seems to be a more reasonable
+view, for we can see and definitely prove that neither of these extreme
+views was correct but that there was much truth in each of them. To-day
+we recognize that certain diseases, such as typhoid, cholera,
+tuberculosis and many others, are caused by the presence of bacteria in
+the body, and it is just as definitely known that such maladies as
+malaria and sleeping sickness are caused by animal parasites.
+
+Then there is a long list of other epidemic diseases, such as smallpox,
+measles and scarlet fever, the exact cause of which has not been
+determined. Many of these are believed to be due to micro-organisms of
+some kind, and if so they will almost certainly sooner or later be
+found. Curiously enough most of the diseases in this last class and many
+of those in the first are contagious, while all that are caused by
+animal parasites are, as far as is known, infectious but not contagious.
+
+
+INFECTIOUS AND CONTAGIOUS DISEASES
+
+It is important that we keep in mind this distinction. By contagious
+diseases are meant those that are transmitted by contact with the
+diseased person either directly, by touch, or indirectly by the use of
+the same articles, by the breath or effluvial emanations from the body
+or other sources. Small-pox, measles, influenza, etc., are examples of
+this group. By infectious diseases are meant those which are
+disseminated indirectly, that is, in a roundabout way by means of water
+or food or other substances taken into or introduced into the body in
+some way. Typhoid, malaria, and yellow fever, cholera and others are
+examples of this class. Thus it is evident that all of the contagious
+diseases may be infectious, but many of the infectious diseases are not
+as a rule contagious, although some of them may become so under
+favorable conditions.
+
+Just one example will show the importance of knowing whether a disease
+is contagious or infectious. Until a few years ago it was believed that
+yellow fever was highly contagious and every precaution was taken to
+keep the disease from spreading by keeping the infected region in strict
+quarantine. This often meant much hardship and suffering and always a
+great financial loss. We now know that it is infectious only and not
+contagious, and that all this quarantine was unnecessary. The whole
+fight in controlling an outbreak of yellow fever or in preventing such
+an outbreak is now directed against the mosquito, the sole agent by
+which the disease can be transmitted from one person to another.
+
+
+EFFECT OF THE PARASITE ON THE HOST
+
+We have seen how a few parasites in or on an animal do not as a rule
+produce any appreciable ill effects. This is of course a most fortunate
+thing for us, for the parasitic germs are everywhere.
+
+There is perhaps "more truth than poetry" in the following newspaper
+jingle:
+
+  "Sing a song of microbes,
+    Dainty little things,
+  Eyes and ears and horns and tails,
+    Claws and fangs and stings.
+  Microbes in the carpet,
+    Microbes in the wall,
+  Microbes in the vestibule,
+    Microbes in the hall.
+  Microbes on my money,
+    Microbes in my hair,
+  Microbes on my meat and bread,
+    Microbes everywhere.
+  Microbes in the butter,
+    Microbes in the cheese,
+  Microbes on the knives and forks,
+    Microbes in the breeze.
+  Friends are little microbes,
+    Enemies are big,
+  Life among the microbes is--
+    Nothing '_infra dig_.'
+  Fussy little microbes,
+    Millions at a birth,
+  Make our flesh and blood and bones,
+    Keep us on the earth."
+
+While of course most of these microbes are to be regarded as absolutely
+harmless and some as very useful, many have the power to do much injury
+if the proper conditions for their rapid development should at any time
+exist. While the size of the parasite is always a factor in the damage
+that it may do to the host the factor of numbers is perhaps of still
+greater importance because of the power of very rapid multiplication
+possessed by so many of the smaller forms.
+
+Certain minute parasites in the blood may cause little or no
+inconvenience, but should they begin to multiply too rapidly some of the
+capillaries may be filled up and trouble thus result. Or take some of
+the larger forms. A few intestinal worms may cause no appreciable effect
+on the host, but as soon as their numbers increase serious conditions
+may come about simply by the presence of the great masses in the host
+even if they were not robbing it of its nourishment. Many instances are
+known where such worms have formed masses that completely clogged up the
+alimentary canal. Such injuries as these may be regarded as mechanical
+injuries. Some parasites injure the host only when they are laying their
+eggs or reproducing the young. These may clog up passages or some of
+them may be carried to some more sensitive part of the body where the
+damage is done. The guinea-worm of southwestern Asia and of Africa lives
+in the body of its host for nearly a year sometimes attaining a great
+length and migrating through the connective tissue to different parts of
+the body causing no particular inconvenience until it is ready to lay
+its eggs when it comes to the surface and then great suffering may
+result. The African eye-worm is another example of a parasite causing
+mechanical injury only at certain times. It works in the tissues of the
+body sometimes for a long while, doing no harm unless it finds its way
+to the connective tissue of the eyeball.
+
+It is known that many of the germs which cause diseases cannot get into
+the body unless the protecting membranes have first been injured in some
+way. Thus the germs that cause plague and lockjaw find their way into
+the system principally through abrasions of the skin. Many physicians
+have come to believe that the typhoid fever germ cannot get into the
+body from the intestine where it is taken with our food or drink unless
+the walls of the intestine have been injured in some way. It is well
+known that of the many parasites that inhabit the alimentary canal some
+rasp the surface and others bore through into the body cavity. This in
+itself may not be a serious thing, but if the mechanical injury thus
+caused opens the way for malignant germs, baneful results may follow.
+Even that popular disease appendicitis is believed to be due sometimes
+to the injury caused by the work of parasites in the appendix.
+
+Parasites may cause morphological or structural changes in the tissues
+of their hosts. The stimulation caused by their presence may result in
+swellings or excresences or other abnormal growths. Interesting examples
+of this are to be found in the way in which pearls are formed in various
+mollusks. In the pearl oysters of Ceylon occur some of the best pearls.
+If these are carefully sectioned there may usually be found at the
+center the remains of certain cestode larvæ whose presence in the oyster
+caused it to deposit the nacreous layers that make up the pearl. Other
+parasites cause similar growths in various shellfish. The great
+enlargements of the arms or legs or other parts of the body seen in
+patients affected with elephantiasis is an abnormal growth due to the
+presence of the parasitic filaræ in some of the lymph-glands where they
+have come to rest.
+
+Finally, the parasite may exert a direct physiological effect on the
+host. This is evident when the parasite demands and takes a portion of
+the nourishment that would otherwise go to the building up of the host.
+Sometimes this is of little importance, but at other times it may be a
+matter of life or death to the infected animal. The physiological
+effect produced may be due to the toxins or poisonous matters that are
+given off by the parasite while it is living in the host's body. Thus it
+is believed that the malarial patients usually suffer less from the
+actual loss of red blood-corpuscles that are destroyed by the parasite
+than they do from the effects of the poisonous excretions that are
+poured into the circulation when the thousands of corpuscles break to
+release the parasites.
+
+One other point in regard to the relation of the parasite to its host
+and this part of the subject may be dismissed. From our standpoint we
+look upon the presence of parasites in the body as an abnormal
+condition. From a biological standpoint their presence there is
+perfectly normal; it is a necessary part of their life. We think that
+they have no business there, but from the viewpoint of the parasites
+their whole business is to be just there. If they are not, they perish.
+And when we take a dose of quinine or other drug we are killing or
+driving from their homes millions of these little creatures who have
+taken up their abode with us for the time being. But they interfere with
+our health and comfort, so they must go.
+
+
+
+
+CHAPTER II
+
+BACTERIA AND PROTOZOA
+
+
+BACTERIA
+
+On the border line between the plant and the animal worlds are many
+forms which possess some of the characteristics of both. Indeed when an
+attempt is made to separate all known organisms into two groups one is
+immediately confronted with difficulties. In looking over the text-books
+of Botany we will find that certain low forms are discussed there as
+belonging with the plants, and on turning to the manuals of Zoölogy we
+will find that the same organisms are placed among the lowest forms of
+animals. The question is of course of little actual importance from
+certain points of view. It serves, however, to show the close relation
+of all forms of life, and from a medical standpoint it may be of very
+great importance owing to the difference in the life-habits, methods of
+reproduction and methods of transmission of many of the forms that cause
+disease. We have already seen that none of the diseases that are caused
+by animal parasites is contagious, while many of those caused by
+bacteria are both contagious and infectious.
+
+Just over on the plant side of this indefinite border line are the
+minute organisms known as bacteria. Their numbers are infinite and they
+are found everywhere. The majority of them are beneficial to mankind in
+one way or another, but some of them cause certain of the diseases that
+we will have to discuss later so attention may be called here to a few
+of the important facts in regard to their organization and life-history
+in order that we may better understand how they may be so easily
+transferred from one host to another.
+
+Although these bacilli are so extremely minute (Fig. 7), some of them so
+small that they cannot be seen with the most powerful microscopes, they
+differ in size, shape, methods of division and spore-formation. Each
+species makes a characteristic growth on gelatin, agar or other media
+upon which it may be cultivated. In this way as well as by the
+inoculation of animals the presence of the ultramicroscopic kinds may be
+demonstrated.
+
+The method of reproduction is very simple. They increase to a certain
+point in size, then divide. This growth and division takes place very
+rapidly. Twenty to thirty minutes is sufficient time in some cases for
+a just-divided cell to attain full size and divide again. Thus in a few
+days time the number of bacteria resulting from a single individual
+would be inconceivable if they should all develop.
+
+Fortunately for us, however, they do not all multiply so rapidly as this
+and besides there are natural checks, not the least of which are the
+substances given off by the bacteria themselves in their growth and
+development. Such excretions often serve to inhibit further
+multiplication. Sometimes, though not often, they form spores which not
+only provide for a more rapid multiplication, but enable the organism to
+live under conditions that would otherwise prove fatal to it.
+
+Bacteria may be conveniently grouped under two heads: those that live
+upon dead organic matter, known as the saprophytic forms, and those that
+are found in living plants or animals, the true parasites. Such a
+grouping is not always entirely satisfactory, for many of the kinds that
+live saprophytically under normal conditions may become parasitic if
+opportunity offers, and also many of those that are usually regarded as
+parasitic may be grown in cultures of agar or other media, under which
+conditions they may be regarded as living saprophytically.
+
+It is this power of easily adapting themselves to different conditions
+that makes many of the kinds dangerous. The bacillus which causes
+tetanus or lockjaw will illustrate this. It is a rather common bacillus
+in soil in many localities. As long as it remains there it is of no
+special importance, but if it is introduced into the body through a
+scratch or any other wound it becomes a very serious matter.
+
+We may say, then, that the effect the bacillus has on the host depends
+largely on the host. Not only does it depend on what the host is, but
+the particular condition of the host at the time of infection is of
+importance. Children are subject to many diseases that adults seldom
+have. Hunger, thirst, fatigue, exposure and other factors may make a
+person susceptible to the actions of certain bacteria that would be
+harmless under other conditions.
+
+The minute size and great numbers of the bacteria make their
+dissemination a comparatively simple matter. They may be carried in the
+air as minute particles of dust; they may be carried in water or milk;
+they may be carried on the clothing or on the person from one host to
+another, or they may be disseminated in scores of other ways. In other
+chapters, particularly the one dealing with the house-fly and typhoid,
+we shall see how it is that insects are often important factors in
+spreading some of the most dreaded of the bacterial diseases.
+
+
+THE PROTOZOA
+
+The Protozoa, or one-celled animals, belonged to an unknown world before
+the invention of the microscope. The first of these instruments enabled
+the early observers to see some of the larger and more conspicuous
+members of the group and each improvement of the microscope has enabled
+us to see more and more of them and to study in detail not only the
+structure but to follow the life-history of many of them.
+
+_The Amoeba._ With some, as the common amoeba (Fig. 8), a minute
+little form that is to be found in the slime at the bottom of almost any
+body of water, the life-history is extremely simple. The organism itself
+consists of a minute particle of protoplasm, a single cell with no
+definite shape or body-wall and no specialized organs or apparatus for
+carrying on the life-functions. It lives in the slime or ooze in fresh
+or salt water, takes its food by simply flowing over the particle that
+is to be ingested, grows to a certain limit of size, then divides into
+two more or less equal parts, each part becoming a new animal that goes
+on with its development as did the parent form. This process of growth
+and division may go on for many generations, but cannot continue
+indefinitely unless there is a conjugation of two separate individuals.
+This process of conjugation is just the opposite to that of division.
+Two amoeba flow together and become one. It seems to rejuvenate the
+organism so that it is able to go on with its division and thus fulfil
+its life-mission which is the same for these lowly animals as with the
+higher, that of perpetuating the species.
+
+_Classes of Protozoa._ The group or Phylum Protozoa is divided into four
+smaller groups or classes. The amoeba belongs to the lowest of these,
+the Rhizopoda. Rhizopoda means "root-footed," and the name is applied to
+these animals because most of them move about by means of root-like
+processes known as pseudopodia or "false feet." This is by far the
+largest class and contains thousands of forms, mostly living in salt
+water but there are many fresh-water species. They are non-parasitic,
+but some of them by their presence in the body may cause such diseases
+as dysentery, etc.
+
+[Illustration: FIG. 7--Typhoid Fever bacilli. (After Muir and
+Ritchie.)]
+
+[Illustration: FIG. 8--_Amoeba_, showing the forms assumed by a single
+individual in four successive changes. (From Kellogg's Elementary
+Zoöl.)]
+
+[Illustration: FIG. 9--_Euglina virdis._ (After Saville Kent.)]
+
+[Illustration: FIG. 10--_Spirocheta duttoni_, × 4500. (After Breinl and
+Carter.)]
+
+The next class which may be known as the whip-bearers (_Mastigophora_)
+includes those Protozoa that move by fine undulating processes called
+flagella. One of the common representatives of this class is the little
+green _Euglena_ (Fig. 9), whose presence in standing ponds and puddles
+often imparts a greenish color to the water. Then in the salt water near
+the surface there are often myriads of minute _Noctiluca_ whose
+wonderfully phosphorescent little bodies glow like coals of fire when
+the water is disturbed at night. Although this class contains fewer
+forms than the preceding some of these have within recent years been
+found to be of great importance because they live as parasites on man
+and other animals. The trypanosome whose presence in the blood and
+tissues of the patient causes that dreadful disease which ends in
+sleeping sickness belongs here as well as do several other similar kinds
+that produce serious troubles for various mammals and birds. The
+Spirochæta, about which there has been so much recent discussion, also
+belong here. These are simple spiral-like forms (Fig. 10), that are
+sometimes classed with the simple plants, bacteria, but Nuttall and
+others have shown very definitely that they should be classed with the
+simplest animals, the Protozoans. These are the cause of relapsing
+fevers in man and of several diseases of domestic animals. It is
+believed by certain eminent zoölogists that when the germ that causes
+yellow fever is discovered it will be found to belong to this group.
+
+The members of the class Infusoria, so called because they were early
+found to be abundant in various infusions, are characterized by numerous
+fine cilia or hair-like organs by means of which the organism moves
+about and procures its food. The well-known "slipper animalcule"
+(_Paramoecium_) (Fig. 11), and the "bell-animalcule" (_Vorticella_)
+(Fig. 12) are two common representatives. The _Paramoecia_ were the
+animals mostly used by Jennings in his wonderfully interesting
+experiments on the behavior of these lowly forms of life. He showed that
+they always reacted in a certain definite way in response to particular
+stimuli, and he was led to believe that he could see "what must be
+considered the beginnings of intelligence and of many other qualities
+found in the higher animals." A species of _Vorticella_ was probably the
+first Protozoan that was ever observed. An old Dutch microscopist, Anton
+von Leeuwenhoek, in 1675, while studying with lenses of his own
+manufacture, discovered and described forms which undoubtedly belong to
+this genus. Few if any of the Infusoria are pathogenic, although some
+are said to be associated with certain intestinal diseases both in man
+and the lower animals (Fig. 13).
+
+[Illustration: FIG. 11--_Paramoecium._ (From Kellogg's Elementary
+Zoöl.)]
+
+[Illustration: FIG. 12--_Vorticella_, one individual with the stalk
+coiled, the other with the stalk extended. (From Kellogg's Elementary
+Zoöl.)]
+
+[Illustration: FIG. 13--Pathogenic Protozoa; a group of intestinal
+parasites. _A_, _B_, _Megastoma entericum_, _C_, _Balantidum entozoon_.
+(After Calkins.)]
+
+The last class, the Sporozoa, or the spore-forming animals, while small
+in the number of known species, only about three hundred kinds being
+known, is extremely important. A number of diseases in man and other
+animals are due to the presence of these Sporozoans, for they are all
+parasitic. Few if any animals are exempt from their attacks. They even
+attack other minute Protozoa. One hundred and fifty-seven species have
+been recorded as attacking insects, one hundred species attack birds,
+fifty-two reptiles, eighty crustaceans, twenty-two fish, and so through
+the list. Ten have been recorded as attacking man. In some instances the
+parasite is always present in the host and some hosts may harbor several
+different species of Sporozoa.
+
+Very little work had been done on this group of parasites prior to 1900.
+Since that time most of the species that we now know have been
+discovered, and within the last few years the life-histories of many of
+these have been worked out quite completely. No other group of animals
+is being studied more to-day by both the physicians and biologists.
+
+The Sporozoa vary greatly in appearance, organization and life-history.
+They are so very plastic that they can adapt themselves readily to their
+various hosts, hence we have a great variety of forms. But they all
+agree in certain characters; all take their food and oxygen and carry on
+excretory processes by osmosis, _i.e._, through the body-wall; all are
+capable of some kind of locomotion, some have one or more flagella,
+others move by a pseudopod movement. Some are capable of moving from
+cell to cell in the body as do the white blood-corpuscles. They all
+agree in the production of spores--hence the name.
+
+At certain stages in their development the nucleus within the body of
+the organism divides again and again until there are a great many
+daughter nuclei, each accompanied by a small mass of protoplasm, often
+inclosed in a little sac or cyst of its own. This is the process of
+spore-formation and we see that from a single individual we may have by
+division, not two animals as in the amoeba, but a score or more of
+them. The little cysts or capsules that inclose them enable them to
+resist without injury many vicissitudes that would otherwise destroy
+them. They may dry up or freeze or lie for a long time in the ground or
+water until the time comes when they are introduced into another host.
+
+The class Sporozoa is divided into five small groups or orders. Nearly
+all of these contain forms that are of more or less importance, but the
+ones that live in the blood-cells (_Hæmosporidiida_) are of the most
+interest to us because the parasites that cause the malarial fevers and
+various other diseases belong here. These are dependent on two hosts for
+their existence, the sexual generation usually occuring in an insect or
+other invertebrate and the asexual generation in some vertebrate.
+
+
+
+
+CHAPTER III
+
+TICKS AND MITES
+
+
+The other group or Phylum of animals with which we will be particularly
+concerned is known as the Arthropoda, which means "jointed-feet" and
+includes the crayfish, crabs, spiders, mites, ticks and insects. Of
+these only the last three are of interest to us now. It is customary to
+speak of spiders, mites and ticks as insects, but as they have four
+pairs of legs, instead of three pairs, in the adult stage, and as their
+bodies are not divided into three distinct regions as in the insects,
+they are placed in a different class.
+
+
+GENERAL CHARACTERS OF TICKS
+
+The ticks are all comparatively large, that is, they are all large
+enough to be seen with the unaided eye even in their younger stages and
+some grow to be half an inch long. When filled with blood the tough
+leathery skin becomes much distended often making the creature look more
+like a large seed than anything else (Fig. 14). This resemblance is
+responsible for some of the popular names, such as "castor-bean tick,"
+etc.
+
+The legs of most species are comparatively short, and the head is small
+so that they are often hardly noticeable when the body is distended. The
+sucking beak which is thrust into the host when the tick is feeding is
+furnished with many strong recurved teeth which hold on so firmly that
+when one attempts to pull the tick away the head is often torn from the
+body and left in the skin. Unless care is taken to remove this, serious
+sores often result.
+
+Ticks are wholly parasitic in their habits. Some of them live on their
+host practically all their lives, dropping to the ground to deposit
+their eggs when fully mature. Others leave their host twice to molt in
+or on the ground. The female lays her eggs, 1,000 to 10,000 of them, on
+the ground or just beneath the surface. The young "seed-ticks" that
+hatch from these in a few days soon crawl up on some near-by blade of
+grass or on a bush or shrub and wait quietly and patiently until some
+animal comes along. If the animal comes close enough they leave the
+grass or other support and cling to their new-found host and are soon
+taking their first meal. Of course thousands of them are disappointed
+and starve before their host appears, but as they are able to live for a
+remarkably long time without taking food their patience is often
+rewarded and the long fast ended.
+
+Those species which drop to the ground to molt must again climb to some
+favorable point and wait for another host on which they may feed for a
+while. Then they drop to the ground for a second molt and if they are
+successful in gaining a new host for the third time they feed and
+develop until fully mature and the female is ready to lay her eggs. The
+Texas fever tick, and some others, as we shall see, do not drop to the
+ground to molt but once having gained a host remain on it until ready to
+deposit their eggs.
+
+The young ticks have only six legs (Fig. 15) but after the first molt
+they all have eight.
+
+
+TICKS AND DISEASE
+
+_Texas Fever._ Ever since stockmen began driving southern cattle into
+states further north it has been noted that the roads over which they
+were driven became a source of great danger to northern cattle. Often
+80% to 90% of the native cattle died after a herd of southern cattle
+passed through their region and the losses became so great that both
+state and national laws were passed prohibiting the driving or shipping
+of southern cattle into northern states.
+
+[Illustration: FIG. 14--Castor Bean Tick (_Ixodes ricinus_) not fully
+gorged.]
+
+[Illustration: FIG. 15--Texas fever tick, just hatched; has only six
+legs.]
+
+[Illustration: FIG. 16--Texas fever tick (_Margaropus annulatus_) young
+adult not fully gorged.]
+
+[Illustration: FIG. 17--_Amblyomma variegatum_ several ticks belonging
+to this genus transmit _Piroplasma_ which cause various diseases of
+domestic animals.]
+
+But for years the cause of this fever, which came to be known as the
+Texas fever, was not known. The southern cattle themselves seemed
+healthy enough and it was difficult to understand how they could give
+the disease to the others. It was early noticed, too, that it was not
+necessary for the northern cattle to come in direct contact with the
+others in order to contract the disease. Indeed the disease was not
+contracted in this way at all. All that was necessary for them was to
+pass along the same roads or feed in the same pastures or ranges. Still
+more puzzling was the fact that these places did not seem to become a
+source of danger until some weeks after the southern cattle had passed
+over them and then they might remain dangerous for months.
+
+In 1886 Dr. Theobald Smith of the Bureau of Animal Industry, United
+States Department of Agriculture, found that the fever was caused by the
+presence in the infected cattle of a minute Sporozoan parasite
+(_Piroplasma bigeminum_). Further investigations and experiments proved
+conclusively that this parasite was transmitted from the infected to the
+well animal only by the common cattle tick now known as the Texas fever
+tick (Fig. 16).
+
+The infection is not direct, that is, the tick does not feed on one
+host then pass to another carrying the disease germs with it. Unlike
+many other ticks the Texas fever tick does not leave its host until it
+is fully developed. When the female is full grown and gorged she drops
+to the ground and lays from 2,000 to 4,000 eggs which soon hatch into
+the minute "seed-ticks" which make their way to the nearest blade of
+grass or weed or shrub and patiently wait for the cattle to come along.
+
+If the mother tick had been feeding on an animal that was infected with
+the Texas fever parasite, her body was filled with the minute organisms
+of which some found their way into the eggs so that the young ticks
+hatching from them were already infected and ready to carry the
+infection to the first animal they fed upon.
+
+It took many years of hard patient work to learn all this, but the
+knowledge thus obtained cleared up much of the mystery in connection
+with the occurrence of the fever in the north and, as we shall see,
+suggested the possibility of other diseases being communicated in the
+same way.
+
+It was found that the southern cattle in the region where the ticks
+occur normally, usually have a mild attack of the disease when they are
+young and although they may be infected with the parasite all the rest
+of their lives it does not affect them seriously. These cattle are
+almost always infected with ticks, and when taken north where the ticks
+do not occur naturally and where the cattle are therefore non-immune,
+some of the mature ticks drop to the ground and lay their eggs which in
+a few weeks hatch out and are ready to infect any animal that passes by.
+The northern cattle not being used to the disease soon sicken and die.
+
+It is estimated that the annual loss due to this disease and the ravages
+of the tick in the United States is over $100,000,000, so of course most
+determined efforts are being made to stamp it out. Formerly various
+devices for dipping the tick-infested cattle into some solution that
+would kill the ticks were resorted to, but it was always expensive and
+never very satisfactory. The immunizing of the cattle by inoculating
+them when they were young with infected blood has been practised. Very
+recent investigations have shown that it is possible and practicable to
+rid pastures of ticks by a system of feed-lots and pasture rotation. The
+aim is to have as many of the ticks as possible drop to the ground on
+land where they may be destroyed and to so regulate the use of the
+pasture that the ticks in all of them may eventually be left to starve.
+
+Several similar diseases of cattle, many of them probably identical
+with Texas fever, occur in other parts of the world where the losses are
+sometimes appalling. Horses, sheep, dogs, and other animals are also
+affected with diseases caused by the same group of Protozoan parasites.
+Most of them have been shown to be transmitted by various species of
+ticks (Fig. 17) so that from an economical standpoint these little pests
+are becoming of prime importance. Not only do they transmit the disease
+germs that infect domestic animals but they are known to be responsible
+for at least two diseases of men, Rocky Mountain spotted fever and the
+relapsing fevers.
+
+_Spotted Fever._ The first of these is a disease that for some years has
+been puzzling the physicians in Idaho and Montana and other mountainous
+states. A few years ago certain observers recorded finding Protozoan
+parasites in the blood of those suffering from the disease, and although
+more recent investigations have failed to confirm these particular
+observations it is now quite generally believed that the disease is
+caused by some such parasite and that the organism is transferred from
+one host to another by certain species of ticks that live on wild
+mammals of the region where the disease exists. Dr. H.T. Ricketts, who
+has made a special study of the disease, has shown:
+
+     "1. That the period of activity of the disease is limited to the
+     season during which the adult female and male ticks attack man.
+
+     "2. That in practically all cases of this disease it can be shown
+     that the patient has been bitten by a tick.
+
+     "3. That the period between the tick bite and the onset of the
+     disease in the many animals he has experimented with corresponds
+     very closely to this period as observed in man.
+
+     "4. That infected ticks are to be found in the locality where the
+     disease occurs.
+
+     "5. That the virus of spotted fever is very intimately associated
+     with the tissues of the tick's body as is shown by the fact that
+     the female passes the infection on to her young through her eggs,
+     and further, by the observation that in either of the two earlier
+     stages of the life cycle the disease may be contracted by biting a
+     sick animal and communicated to other animals after molting or even
+     after passing through an intermediate stage."
+
+Professor R.A. Cooley of Montana, from whose report the above quotation
+is taken, has also made studies of the habits of the tick and believes
+there can be no doubt that it is the disseminator of the disease.
+
+_Relapsing Fever._ The relapsing fever is an infectious disease or
+possibly a group of closely related infectious diseases occurring in
+various parts of the world. Occasionally it is introduced into America,
+but it does not seem to spread here. It has been shown that the disease
+is communicated from one person to another by means of blood-sucking
+insects. In Central Africa where the disease is very prevalent a certain
+common tick (_Ornithodoros moubata_) (Fig. 18) is known to transmit the
+disease. This tick lives in the resting places and around the huts of
+the natives and has habits very similar to the bedbug of other climes,
+feeding at night and hiding during the day. It attacks both man and
+beast and is one of the most dreaded of all the African pests.
+
+Nathan Bank, our foremost authority on ticks, in summing up the evidence
+against them says:
+
+     "It is therefore evident that all ticks are potentially dangerous.
+     Any tick now commonly infesting some wild animal, may, as its
+     natural host becomes more uncommon, attach itself to some domestic
+     animal. Since most of the hosts of ticks have some blood-parasites,
+     the ticks by changing the host may transplant the blood-parasites
+     into the new host producing, under suitable conditions, some
+     disease. Numerous investigators throughout the world are studying
+     this phase of tick-life, and many discoveries will doubtless
+     signalize the coming years."
+
+
+MITES
+
+The mites are closely related to the ticks, and although none of them
+has yet been shown to be responsible for the spread of any disease their
+habits are such that it would be entirely possible for some to transmit
+certain diseases from one host to another, from animal to animal, from
+animal to man, or from man to man. A number of these mites produce
+certain serious diseases among various domestic animals and a few are
+responsible for certain diseases of men.
+
+_Face-mites._ Living in the sweat-glands at the roots of hairs and in
+diseased follicles in the skin of man and some domestic animals are
+curious little parasites that look as much like worms as mites (Fig.
+19). Such diseased follicles become filled with fatty matter, the upper
+end becomes hard and black and in man are known as blackheads. If one of
+these blackheads is forced out and the fatty substance dissolved with
+ether the mites may be found in all stages of development. The young
+have six legs, the adult eight. The body is elongated and transversely
+wrinkled. In man they are usually found about the nose and chin and neck
+where they do no particular harm except to mar the appearance of the
+host and to indicate that his skin has not had the care it should have.
+Very recently certain investigators have found that the lepræ bacilli
+are often closely associated with these face mites and believe that they
+may possibly aid in the dissemination of leprosy. It is also thought
+that they may sometimes be the cause of cancer, but as yet these
+theories have not been proven by any conclusive experiment.
+
+In dogs and cats these same or very similar parasites cause great
+suffering. In bad cases the hair falls out and the skin becomes scabby.
+Horses, cattle and sheep are also attacked. The disease caused by these
+mites on domestic animals is not usually considered curable except in
+its very early stages when salves or ointments may help some.
+
+_Itch-mites._ "As slow as the seven-years' itch" is an expression, the
+meaning of which many could appreciate from personal experience, for it
+certainly seemed to take no end of time to get rid of the itch once it
+was contracted. Just why seven years should have been set for the limit
+of the disease is not clear, for if the little roundish mites that cause
+the disease live for seven years on a host they are not going to move
+out voluntarily even if their seven-year lease has expired.
+
+[Illustration: FIG. 18--_Ornithodorus moubata_, the Tick that Transmits
+Relapsing Fever. From Boyce's "Mosquito or Man."]
+
+[Illustration: FIG. 19--The follicle mite (_Demodex folliculorum_).
+(After Murray.)]
+
+[Illustration: FIG. 20--Itch-mite (_Sarcoptes scabiei_). (After
+Murray.)]
+
+[Illustration: FIG. 21--Harvest-mites or "jiggers." (_Leptus irritaus_
+and _L. americanus_.) (After Riley.)]
+
+The minute whitish mites (Fig. 20) that cause this disgusting disease
+are barely visible to the naked eye. They are usually very sluggish but
+become more active when warmed. They live in burrows just beneath the
+outer layer of skin, sometimes extending deeper and causing most intense
+itching. As the female burrows, she lays her eggs from which come the
+young mites that are to spread the infection. Various sulphur ointments
+and washes are used as remedies. Cleanliness will prevent infection.
+
+Closely related to the itch-mite of man (_Sarcoptes scabiei_) are
+several kinds attacking domestic animals, causing mange, scab, etc. The
+variety infesting horses burrows in the skin and produces sores and
+scabs, and is a source of very great annoyance. These mites may also
+migrate to man. Tobacco water and sulphur ointments are used as
+remedies.
+
+Horses and cattle are also infested by other mites (_Psoroptes
+communis_) which cause the common mange. These do not burrow into the
+skin but live outside in colonies, feeding on the skin and causing
+crusts or scabs. The inflammation causes the animal to scratch and rub
+constantly and often causes the loss of much of the hair.
+
+_Harvest-mites._ A score or more of different varieties of mites cause
+many other diseases of domestic animals, such as the scab of sheep and
+hogs and chickens, various other manges of the horses and cattle and
+dogs, etc. But we need to call attention to just one more example, that
+of the harvest-mites or jiggers (Fig. 21). Professor Otto Lugger, from
+whose report on the _Parasites of Man and Domestic Animals_ most of
+these notes in regard to the mites are taken, thus feelingly refers to
+this pest.
+
+     "About the very worst pests of man and domesticated animals are the
+     Harvest-bugs, Red-bugs or Jiggers.... Men and animals passing
+     through low herbage that harbors them are attacked by these pests,
+     which, whenever they succeed in finding a host, burrow in and under
+     the skin, causing intolerable itching and sores, the latter caused
+     by the feverish activity of the finger-nails of the host, if that
+     should be a man, whose energy in scratching, apparently, cannot be
+     controlled and who is bound forcibly to remove the intruders. The
+     writer has been there! Those who have ever passed through meadows
+     infested with red-bugs will remember the occasion."
+
+Horses, cattle, dogs and cats and other animals suffer also. Again
+sulphur ointments are the best remedies.
+
+     "The normal food of these mites must, apparently, consist of the
+     juices of plants, and the love of blood proves ruinous to those
+     individuals which get a chance to indulge it. For, unlike the true
+     chigoe, the female of which deposits eggs in the wound she makes,
+     these harvest-mites have no object of the kind, and when not killed
+     at the hands of those they torment they soon die victims to their
+     sanguinary appetite."
+
+
+
+
+CHAPTER IV
+
+HOW INSECTS CAUSE OR CARRY DISEASE
+
+
+It has been estimated that there are about four thousand species or
+kinds of Protozoans, about twenty-five thousand species of Mollusks,
+about ten thousand species of birds, about three thousand five hundred
+species of mammals, and from two hundred thousand to one million species
+of insects, or from two to five times as many kinds of insects as all
+other animals combined.
+
+Not only do the insects preponderate in number of species, but the
+number of individuals belonging to many of the species is absolutely
+beyond our comprehension. Try to count the number of little green aphis
+on a single infested rose-bush, or on a cabbage plant; guess at the
+number of mosquitoes issuing each day from a good breeding-pond;
+estimate the number of scale insects on a single square inch of a tree
+badly infested with San José scale; then try to think how many more
+bushes or trees or ponds may be breeding their millions just as these
+and you will only begin to comprehend the meaning of this statement.
+
+As long as these myriads of insects keep in what we are pleased to call
+their proper place we care not for their numbers and think little of
+them except as some student points out some wonderful thing about their
+structure, life-history or adaptations. But since the dawn of history we
+find accounts to show that insects have not always kept to their proper
+sphere but have insisted at various times and in various ways in
+interfering with man's plans and wishes, and on account of their
+excessive numbers the results have often been most disastrous.
+
+Insects cause an annual loss to the people of the United States of over
+$1,000,000,000. Grain fields are devastated; orchards and gardens are
+destroyed or seriously affected; forests are made waste places and in
+scores of other ways these little pests which do not keep in their
+proper places are exacting this tremendous tax from our people.
+
+These things have been known and recognized for centuries, and scores of
+volumes have been written about the insects and their ways and of
+methods of combating them.
+
+But it is only in recent years that we have begun to realize the really
+important part that insects play in relation to the health of the people
+with whom they are associated. Dr. Howard estimates that the annual
+death rate in the United States from malaria is about twelve thousand,
+entailing an annual monetary loss of about $100,000,000, to say nothing
+of the suffering and misery endured by the afflicted. All this on
+account of two or three species of insects belonging to the mosquito
+genus _Anopheles_.
+
+Yellow fever, while not so widespread, is more fatal and therefore more
+terrorizing. Its presence and spread are due entirely to a single
+species of mosquito. Flies, fleas, bedbugs, and many other insects have
+been shown to be intimately connected with the spread of several other
+most dreaded diseases, so it is no wonder that physicians, entomologists
+and biologists are studying with utmost zeal many of these forms that
+bear such a close relation not only to our welfare and comfort but to
+our lives as well.
+
+It would be out of place to try to give here even a brief outline of the
+classification of insects, such as may be found in almost any of the
+many books devoted to their study.
+
+The most generally accepted classification divides the insects into
+nineteen orders; as the Coleoptera, containing the beetles; the
+Lepidoptera, containing the butterflies and moths; the Hymenoptera
+containing the bees, ants and wasps, etc. Four or five of these orders
+will be of more or less interest to us.
+
+The order Diptera, or two-winged flies, is the most important because to
+this belong the mosquitoes which transmit malaria and yellow fever, and
+the house-fly that has come into prominence since it has been found to
+be such an important factor in the distribution of typhoid and other
+diseases.
+
+
+FLIES
+
+The order Diptera is divided into sixty or more families, many of which
+contain species of considerable economic importance. For our present
+consideration the flies may be divided into two groups or sections:
+those with their mouth-parts fitted for piercing such as the mosquito
+and horse-fly, and those with sucking mouth-parts such as the house-fly,
+blow-fly and others.
+
+Some of the species belonging to the first group are among the most
+troublesome pests not only of man but of our domestic animals as well.
+Next to the mosquitoes the horse-flies (Fig. 22) are perhaps the best
+known of these. There are several species known under various names,
+such as gad-fly, breeze-fly, etc. They are very serious pests of horses
+and cattle, sometimes also attacking man. Their strong, sharp, piercing
+stylets enable them to pierce through the toughest skin of animals and
+through the thin clothing of man. The bite is very severe and
+irritating, and as the flies sometimes occur in great numbers the
+annoyance that they cause is often very great indeed. It has often been
+claimed that these flies as well as the stable-fly and others carry the
+anthrax bacillus on their proboscis from one animal to another, and
+although this may not have been definitely proven the evidence is strong
+enough to make a very good case against the accused. It is interesting
+to note in this connection that anthrax, a very common disease among the
+domestic animals and one which may attack man also, was the first
+disease to be shown to be of bacterial origin. It was only about
+thirty-five years ago that the investigations of Koch and Pasteur
+demonstrated that the presence of this particular germ (_Bacillus
+anthracis_) was the cause of the disease, and it was early recognized
+that such biting flies may be important factors in the spread of the
+disease.
+
+[Illustration: FIG. 22--Horse-fly (_Tabanus punctifer_).]
+
+[Illustration: FIG. 23--Stable-fly (_Stomoxys calcitrans_).]
+
+[Illustration: FIG. 24--A Black-fly (_Simulium sp._). (From Kellogg's
+Amer. Insects.)]
+
+[Illustration: FIG. 25--Screw-worm fly (_Chrysomyia macellaria_).]
+
+[Illustration: FIG. 26--Blow-fly (_Calliphora vomitoria_).]
+
+The stable-fly (Fig. 23) (_Stomoxys calcitrans_) which looks very much
+like the house-fly and, as will be noted later, frequently enters
+houses, is often an important pest of horses and cattle. Its
+blood-sucking habit makes it quite possible that it too may be concerned
+in carrying anthrax and other diseases.
+
+In a later chapter it will be shown how the tsetse-fly, which is
+somewhat like the stable-fly, is responsible for the spread of the
+disease known as the sleeping sickness. This disease is caused by a
+Protozoan parasite, a trypanosome, which is transmitted from one host to
+another by the tsetse-fly.
+
+In Southern Asia and in parts of Africa there is a very serious disease
+of horses known as surra which is caused by a similar parasite
+(_Trypanosoma evansi_). This parasite attacks horses, mules, camels,
+elephants, buffaloes and dogs, and has been recently imported into the
+Philippines. It is supposed that flies belonging to the same genus as
+the horse-fly (_Tabanus_ and others), and the stable-fly (_Stomoxys_)
+and the horn-fly (_Hæmatobia_) are responsible for the spread of the
+disease.
+
+Nagana is one of the most serious diseases of domestic animals in
+Central and Southern Africa. In some sections it is almost impossible to
+keep any kind of imported animals on account of this disease which is
+caused by a parasite (_Trypanosoma brucei_) similar to the one causing
+surra. This parasite is to be found in several different kinds of
+native animals which seem to be practically immune but are always a
+source of danger when other animals are introduced. Two or three species
+of tsetse-flies are responsible for the transmission of this disease.
+
+Another group of flies much smaller but more numerous and much more
+insistent are the black-flies or buffalo-gnats (Fig. 24). For more than
+a century these little flies have been recognized as among the most
+serious pests of stock, particularly in the south where, besides the
+actual loss by death of many animals yearly, the annoyance is so great
+as to sometimes make it impossible to work in the field. Human beings
+are often attacked, and as the bite is poisonous and very painful great
+suffering may result and cases of deaths from such bites have been
+reported.
+
+Belonging to another family, and smaller, but much like the buffalo-gnat
+in habits, are the minute little "punkies" or "no-see-ums" which
+sometimes occur in great swarms in certain regions where they make life
+a burden to man and beast. While it has not been shown that either the
+buffalo-gnats or the punkies are responsible for the transmission of any
+disease, their habits of feeding on so many different kinds of wild and
+domestic animals as well as on man makes it possible for them to act as
+carriers of parasites that might under proper conditions become of
+serious importance. Then, too, the irritation caused by the bites of
+these insects usually causes scratching which may result in abrasions of
+the skin that open the way for various harmful germs, particularly those
+causing skin diseases.
+
+Coming now to the group containing the house-flies and related forms we
+find a number that are of interest on account of the suffering that they
+may cause, particularly in their larval stages.
+
+The screw-worm flies (_Chrysomyia macellaria_) are among the most common
+and important of these (Fig. 25). These "gray flies," as they are
+sometimes called, lay a mass of three or four hundred eggs on the
+surface of wounds. The larvæ which in a few hours hatch from these make
+their way directly into the wound where they feed on the surrounding
+tissue until full grown when they wriggle out and drop to the ground
+where they transform to the pupa and later to the adult fly. Of course
+their presence in the wounds is very distressing to the infected animal,
+and great suffering results. Slight scratches that might otherwise
+quickly heal often become serious sores because of the presence of these
+larvæ.
+
+Many cases are recorded of these flies laying their eggs in the ears or
+nose of children or of persons sleeping out of doors during the day.
+Especially is this apt to occur if there are offensive discharges which
+attract the fly. In such cases the larvæ burrow into the surrounding
+tissues, devouring the mucous membranes, the muscles and even the bones,
+causing terrible suffering and usually, death. The larvæ in such
+situations may be killed with chloroform and, if the case is attended to
+before they have destroyed too much of the tissues, recovery usually
+occurs.
+
+The blow-flies (Fig. 26) (_Calliphora vomitoria_) and the blue-bottle
+flies (Fig. 27), (_Lucilia spp._) and the flesh-flies (Fig. 28)
+(_Sarcophaga spp._) all have habits somewhat like the screw-worm fly.
+Any of them may lay their eggs in wounds on man or animals with the same
+serious results.
+
+The flesh-fly instead of laying eggs deposits the living larvæ upon meat
+wherever it is accessible, and as these develop with astonishing
+rapidity they are able to consume large quantities of flesh in a
+remarkably short time. In this way they may be of some importance as
+scavengers, but it is better to get rid of the waste in other ways than
+to leave it for a breeding-place for flies that are capable of causing
+so much damage and suffering.
+
+Not infrequently the larvæ of certain flies are to be found in the
+alimentary canal where as a rule they do no particular damage.
+Altogether the larvæ of over twenty different species of flies have been
+found in or expelled from the human intestinal canal. In Europe, the
+majority of these larvæ belong to a fly which looks very much like the
+house-fly except that it is somewhat smaller and so is often known as
+"the little house-fly" (Fig. 29) (_Homalomyia canicularis_). The same
+species is very common in the United States, frequently occurring in
+houses. Under certain conditions it may even be more abundant than the
+house-fly. It is believed that the larvæ in the intestinal canal come
+from eggs that have been deposited on the victim while using an outdoor
+privy where the flies are often very abundant. Instances are also on
+record where these larvæ have been discharged from the urethra.
+
+Another fly (_Ochromyia anthropophaga_) occurring in the Congo region
+has a blood-sucking larvæ which is known as the Congo floor-maggot. The
+fly which is itself not troublesome deposits its eggs in the cracks and
+crevices of the mud floors of the huts. The larvæ which hatch from these
+crawl out at night and suck the blood of the victim that may be sleeping
+on the floor or on a low bed.
+
+
+BOT-FLIES
+
+Another group of flies known as the bot-flies (Fig. 30) have their
+mouth-parts rudimentary or entirely wanting so of course they themselves
+cannot bite or pierce an animal. Nevertheless they are the source of an
+endless amount of trouble to stockmen and sometimes even attack man.
+Although these flies cannot bite, the presence of even a single
+individual may be enough to annoy a horse almost to the end of
+endurance. Horses seem to have an instinctive fear of them and will do
+all in their power to get rid of the annoying pests.
+
+The eggs of the house bot-fly are laid on the hair of the legs or some
+other part of the body. The horse licks them off and they hatch and
+develop in the alimentary canal of their host. Sometimes the walls of
+the stomach may be almost covered with them thus of course seriously
+interfering with the functions of this organ. When full grown the larvæ
+pass from the host and complete their transformation in the ground.
+
+[Illustration: FIG. 27--Blue-bottle fly (_Lucilia sericata_).]
+
+[Illustration: FIG. 28--Flesh-fly (_Sarcophaga sp_).]
+
+[Illustration: FIG. 29--"The little house-fly" (_Homalomyia
+canicularis_).]
+
+[Illustration: FIG. 30--Horse bot-fly (_Gastrophilus equi_).]
+
+[Illustration: FIG. 31--Ox warble-fly (_Hypoderma lineata_).]
+
+[Illustration: FIG. 32--Sheep bot-fly (_Gastrophilus nasalis_).]
+
+The bot-flies of cattle or the oxwarbles (Fig. 31) gain an entrance
+into the alimentary canal in the same way, that is, by the eggs being
+licked from the hairs on the body where they have been laid by the adult
+fly. But instead of passing on into the stomach they collect in the
+esophagus and later make their way through the walls of this organ and
+through the tissues of the body until they at last reach a place along
+the back just under the skin. Here as they are completing their
+development they make more or less serious sores on the backs of the
+infested animals. The hides on such animals are rendered nearly
+valueless by the holes made by the larvæ. When fully mature they drop to
+the ground and complete their transformations.
+
+The sheep bot-flies (Fig. 32) lay their eggs in the nostrils of sheep.
+The larvæ pass up into the frontal sinuses where they feed on the mucus,
+causing great suffering and loss. Many other species of animals are
+infested with their own particular species of bots. Several instances
+are recorded where the oxwarble has occurred in man, always causing much
+suffering and sometimes death.
+
+One or more species of bot-flies occurring in the tropical parts of
+America frequently attack man. The early larval stage soon after it has
+entered the skin is known as the _Ver macaque_. Later stages as _torcel_
+or _Berne_. The presence of the larvæ produces very painful and
+troublesome sores. It is supposed that the adult flies (one species of
+which is _Dermatobia cyaniventris_) lay their eggs on the skin which
+the larvæ penetrate as soon as they hatch. It has also been suggested
+that they might reach the subcutaneous tissue by migrating from the
+alimentary canal as do some of the other bot-flies. A very serious eye
+disease, _Egyptian opthalmia_, is known to be spread by the house-flies
+and others. These flies are often abundant about the eyes, especially of
+children suffering from this disease. It is suspected that certain small
+flies (Oscinidæ) in the southern part of the United States are
+responsible for the spread of disease known as "sore eye."
+
+
+FLEAS
+
+The fleas used to be considered as degenerate Diptera and were placed
+with that group but they are now classed as a separate order
+(Siphonaptera). Within recent years these little pests have come into
+special prominence on account of their importance in connection with the
+spread of the plague. The fact that they are so abundant everywhere and
+that they will so readily pass from one host to another makes the
+possibility of their spreading infectious diseases very great. Besides
+the kinds that are concerned in the transmission of plague, which are
+discussed in another chapter, there are many other kinds infesting
+various wild and domesticated animals and a few attacking birds.
+
+One of the most important of these is the jigger-flea or chigoe
+(_Dermatophilus penetrans_, Fig. 33). Various other names such as
+chigger-flea, sand-flea, jigger, chigger are also applied to this insect
+as well as to a minute red mite that burrows into the skin in much the
+same way as the female of the flea. So although they are entirely
+different creatures you can never tell from the common name, whether it
+is the flea or the mite that is being referred to. Both the male and
+female jigger-fleas feed on the host and hop on or off as do other
+fleas, but when the female is ready to lay eggs (Fig. 34), she burrows
+into the skin. Her presence there causes a swelling and usually an ulcer
+which often becomes very serious, especially if the insect should be
+crushed and the contents of the body escape into the surrounding tissue.
+
+These little pests are found throughout tropical and subtropical America
+and have been introduced into Africa and from there have spread to India
+and elsewhere. They attack almost all kinds of animals as well as many
+birds, being of course a source of great annoyance and no inconsiderable
+loss. They are more apt to attack the feet of men, especially those who
+go barefooted. Sometimes they occur in such numbers as to make great
+masses of sores.
+
+On account of being such general feeders they are difficult to control,
+but some relief may be obtained by keeping the houses and barns as free
+as possible from dirt and rubbish and by sprinkling the breeding-places
+of the pest with pyrethrum powder or carbolic water. Those that gain an
+entrance into the skin should be cut out, care being taken to remove the
+insect entire.
+
+
+BEDBUGS
+
+In the order Hemiptera, or the true "bugs" in an entomological sense, we
+find a few forms that may carry disease. The bedbug (Fig. 35) (_Cimex
+lectularis_) has been accused of transmitting plague, relapsing fever
+and other diseases. Very recent investigations show that the common
+bedbug of India (_Cimex rotundatus_) harbors the parasite that causes
+the disease known as _kala azar_, and there is no doubt that it
+transmits the disease.
+
+
+LICE
+
+The sucking lice (Fig. 36) which also belong to this order are suspected
+of carrying some of these same diseases. It is thought that the common
+louse on rats (_Hæmatopinus spinulosus_) is responsible for the spread
+from rat to rat of a certain parasite. (_Trypanosoma lewisi_), which,
+however, does not produce any disease in the rats, but if they are
+capable of acting as alternative hosts for such parasites, it is quite
+possible that they may also carry disease-producing forms.
+
+[Illustration: FIG. 33--Chigo or jigger-flea, male (_Dermatophilus
+penetrans_). (After Karsten.)]
+
+[Illustration: FIG. 34--Chigo, female distended with eggs. (After
+Karsten.)]
+
+[Illustration: FIG. 35--Bedbug (_Cimex lectularis_).]
+
+[Illustration: FIG. 36--Body-louse (_Pediculus vestimenti_). (From
+drawing by J.H. Paine.)]
+
+
+HOW INSECTS MAY CARRY DISEASE GERMS
+
+Insects may carry the germs or parasites which cause disease in a purely
+mechanical or accidental way, that is, the insect may in the course of
+its wanderings or its feeding get some of the germs on or in its body
+and may by chance carry these to the food, or water, or directly to some
+person who may become infected. Thus the house-fly may carry the typhoid
+germs on its feet or in its body and distribute them in places where
+they may enter the human body.
+
+Several other flies as well as fleas, bedbugs, ticks, etc., may also
+carry disease germs in this mechanical way. While this method of
+transmission is just as dangerous as any other, and possibly more
+dangerous because more common, another method in which the insect is
+much more intimately concerned is more interesting from a biological
+standpoint at least and will be discussed more fully in the chapters on
+malaria, yellow fever and elephantiasis.
+
+In these cases the insect is one of the necessary hosts of the parasite,
+which cannot go on with its development or pass from one patient to
+another unless it first enters the insect at a certain stage of its
+life-history.
+
+[Illustration: FIG. 37--One use for the house-fly.]
+
+BABY-BYE.
+
+  1. Baby-Bye,
+  Here's a fly;
+  We will watch him, you and I.
+    How he crawls
+    Up the walls,
+    Yet he never falls!
+  I believe with six such legs
+  You and I could walk on eggs.
+    There he goes
+    On his toes,
+    Tickling Baby's nose.
+
+
+
+
+CHAPTER V
+
+HOUSE-FLIES OR TYPHOID-FLIES
+
+
+The page shown in Fig. 37 was copied from one of our old second readers
+and shows something of the spirit in which we used to regard the
+house-fly. A few of them were nice things to have around to make things
+seem "homelike." Of course they sometimes became too friendly during the
+early morning hours when we were trying to take just one more little nap
+or they were sometimes too insistent for their portion of the dinner
+after it had been placed on the table, but a screen over the bed would
+help us out a little in the morning and a long fly-brush cut from a tree
+in the yard or made of strips of paper tacked to a stick or, still more
+fancy, made of long peacock plumes, would help to drive them from the
+table. Those that were knocked into the coffee or the cream could be
+fished out; those that went into the soup or the hash were never missed!
+
+Not only were the flies regarded as splendid things with which to amuse
+the baby, but they were thought to be very useful as scavengers as they
+were often seen feeding on all kinds of refuse in the yard. Then, too,
+they seemed to be cleanly little things, for almost any time some of
+them could be seen brushing their heads and bodies with their legs and
+evidently having a good clean-up. More than that it never occurred to us
+that it would be possible to get rid of them even should it be thought
+advisable, for they came from "out doors," and who could kill all the
+flies "out doors"?
+
+Fortunately, or otherwise, these halcyon days have gone by and the
+common, innocent, friendly little house-fly is now an outcast convicted
+of many crimes and accused of a long list of others (Fig. 38).
+
+Its former friends have become its sworn enemies. The foremost
+entomologist of the land has suggested that we even change its name and
+give it one that would be more suggestive of the abhorence with which we
+now look upon it.
+
+[Illustration: FIG. 38--The house-fly (_Musca domestica_).]
+
+And all these changes have come about because science has turned the
+microscope on the house-fly and men have studied its habits. We know now
+that as the fly is "tickling baby's nose" it may be spreading there
+where they may be inhaled or where they may be taken into the baby's
+mouth thousands of germs some of which may cause some serious disease.
+We know that as they are buzzing about our faces while we are trying to
+sleep they may, unwittingly, be in the same nefarious business, and we
+know that as they sip from our cups with us or bathe in our coffee or
+our soup or walk daintily over our beefsteak or frosted cake they are
+leaving behind a trail of filth and bacteria, and we know that some of
+these germs may be and often are the cause of some of our common
+diseases. As the typhoid germs are very often distributed in this way,
+Dr. Howard has suggested that the house-fly shall be known in the future
+as the typhoid-fly, not because it is solely responsible for the spread
+of typhoid, but because it is such an important factor in it and is so
+dangerous from every point of view. The names "manure fly" and "privy
+fly" have also been suggested and would perhaps serve just as well, as
+the only object in giving it another name would be to find a more
+repulsive one to remind us constantly of the filthy and dangerous habits
+of the fly.
+
+
+STRUCTURE
+
+In order that we may better understand why it is that the house-fly is
+capable of so much mischief, let us consider briefly a few points in
+regard to its structure, its methods of feeding and its life-history.
+
+The large compound eyes are the most conspicuous part of the head (Fig.
+39). In front, between the eyes, are the three-jointed antennæ, the last
+joint bearing a short, feathery bristle. From the under side of the head
+arises the long, fleshy proboscis (Fig. 40). When this is fully extended
+it is somewhat longer than the head; when not distended and in use it is
+doubled back in the cavity on the under side of the head. About half-way
+between the base and the middle is a pair of unjointed mouth-feelers
+(maxillary palpi). At the tip are two membranous lobes (Fig. 41) closely
+united along their middle line. These are covered with many fine
+corrugated ridges, which under the microscope look like fine spirals and
+are known as pseudotracheæ. Thus it will be seen that the house-fly's
+mouth-parts are fitted for sucking and not for biting. Its food must be
+in a liquid or semi-liquid state before it can be sucked through the
+tube leading from the lobes at the tip up through the proboscis and on
+into the stomach. If the fly wishes to feed on any substance such as
+sugar, that is not liquid, it first pours out some saliva on it and then
+begins to rasp it with the rough terminal lobes of the proboscis, thus
+reducing the food to a consistency that will enable the fly to suck it
+up. Many people think that house-flies can bite and will tell you that
+they have been bitten by them. But a careful examination of the
+offender, in such instances, will show that it was not a house-fly but
+probably a stable-fly, which does have mouth-parts fitted for piercing.
+
+[Illustration: FIG. 39--Head of house-fly showing eyes, antennæ and
+mouth-parts.]
+
+[Illustration: FIG. 40--Proboscis of house-fly, side view.]
+
+[Illustration: FIG. 41--Lobes at end of proboscis of house-fly showing
+corrugated ridges.]
+
+[Illustration: FIG. 42--Wing of house-fly.]
+
+The thorax bears the two rather broad, membranous wings (Fig. 42) which
+have characteristic venation. Three of these veins end rather close
+together just before the tip of the wing, the posterior one of the group
+being bent forward rather sharply a short distance from the tip. The
+stable-fly has this vein slightly curved forward but not nearly so
+conspicuously (Fig. 43).
+
+Nearly all the other flies that are apt to be mistaken for the house-fly
+do not have this vein curved forward. The wings, although apparently
+bare, are covered with a fine microscopic pubescence. Among these fine
+hairs on the wing as well as among similar fine ones and coarser ones
+all over the body, particles of dust and dirt or filth (Fig. 44) or,
+what interests us more just now, thousands of germs may find a temporary
+lodgment and later be scattered through the air as the insect flies. Or
+they may get on our food as the fly feeds or while it rests and combs
+its body with the rows of coarse hairs on its legs.
+
+The legs are rather thickly covered with coarse hairs or bristles and
+with a mat of fine, short hairs. On some of the segments the larger
+hairs are arranged in rows and are used as a sort of comb with which the
+fly combs the dirt from the rest of its body. The last segment (Fig. 45)
+of the leg bears at its tip a pair of large curved claws and a pair of
+membranous pads known as the pulvillæ. On the under side of the pulvillæ
+are innumerable minute secreting hairs (Fig. 46) by means of which the
+fly is able to walk on the wall or ceiling or in any position on
+highly-polished surfaces.
+
+
+HOW THEY CARRY BACTERIA
+
+These same little pads, with their covering of secreting hairs, are
+perhaps the most dangerous part of the insect for they cannot help but
+carry much of the filth over or through which the fly walks, and as this
+may be well stocked with germs the danger is at once apparent.
+
+As the result of a series of carefully planned experiments it has been
+demonstrated that the number of bacteria on a single fly may range all
+the way from 550 to 6,600,000 with an average for the lot experimented
+with of about one and one-fourth million bacteria to each fly. Now where
+do all these bacteria come from? Necessarily from the place where the
+fly breeds or where it feeds.
+
+[Illustration: FIG. 43--Wing of Stable-fly (_Stomoxys calcitrans_).]
+
+[Illustration: FIG. 44--Wing of house-fly showing particles of dirt
+adhering to it.]
+
+[Illustration: FIG. 45--Last three segments of leg of house-fly showing
+the claws, the pulvillæ and the hairs on the legs.]
+
+[Illustration: FIG. 46--Foot of house-fly showing claws, hairs,
+pulvillæ and the minute clinging hairs on the pulvillæ.]
+
+[Illustration: FIG. 47--Larva of house-fly.]
+
+
+LIFE-HISTORY AND HABITS
+
+The eggs of the house-fly may be laid on almost any kind of decaying or
+fermenting material. If this is kept moist and a proper temperature
+maintained the larvæ or maggots (Fig. 47) that hatch from the eggs may
+develop. As a rule, however, these requirements are found only under
+certain conditions and are ordinarily found only in manure heaps or in
+privy vaults or latrines. All observers agree that the female fly
+prefers to deposit her eggs in horse manure when this can be found and
+when this is piled in heaps in the barn-yard (Fig. 48) or in the field
+the heat caused by the decay and fermentation makes ideal conditions for
+the development of the larvæ. Cow manure may serve as a breeding-place
+to a limited extent. The flies are immediately attracted to human
+excrement and breed freely in it when opportunity offers. Decaying
+vegetables or fruit, fermenting kitchen refuse and other materials
+sometimes also serve as breeding-places.
+
+In suitable places in warm weather the eggs will hatch in from eight to
+twelve hours and the larvæ will become fully developed in from eight to
+fourteen days. They then change to pupæ (Fig. 50) in which stage they
+may remain for another eight to twenty days when the adult flies will
+emerge. These figures must necessarily be indefinite because the weather
+and other conditions always vary. Under the most favorable conditions of
+moisture and temperature it is probably never less than eight days from
+egg to adult fly and under unfavorable conditions it may be as long as
+six weeks.
+
+The larvæ thrive best when the manure is kept quite wet. I have often
+found them in almost incredible numbers in stables that had not been
+cleaned for some time. The horses standing there at night added fresh
+material and kept it just wet enough to make conditions almost ideal
+(Fig. 49).
+
+The pupæ are usually found where the manure is a little dryer, but it
+must not be too dry. When the flies issue from the pupæ they push their
+way up to the surface where they remain for a short time and allow the
+body to harden and the wings to dry before they fly away to other manure
+or, as too often happens, to some near-by kitchen or restaurant or
+market place.
+
+[Illustration: FIG. 48--Barn-yard filled with manure. Millions of flies
+were breeding here and infesting all the near-by houses.]
+
+[Illustration: FIG. 49--Dirty stalls; the manure had not been removed
+for some days and the floor was covered with maggots.]
+
+Of course it is impossible for them to issue from this filth without
+more or less of it clinging to their bodies. Now if these flies would
+breed only in barn-yard manure and fly directly from the stable to the
+house there would be comparatively little reason to complain, at least
+from a sanitary standpoint, for the amount of barn-yard filth that they
+carried to our food would be of little consequence. But when they breed
+in privy vaults or similar places, or visit such places before coming
+into the house or dairy or market place the results may be much more
+serious.
+
+
+FLIES AND TYPHOID
+
+It has been abundantly demonstrated that the excrement or the urine of a
+typhoid patient may contain virulent germs for some time before he is
+aware that he has the disease, and it has been shown that the germs may
+be present for weeks or months, and in some cases even years after the
+patient has recovered. If a fly breeds in such infected material, or
+feeds or walks on it, it is very apt to get some of the germs on its
+body where they may retain their virulence for some time, and should it
+visit our food while covered with these germs some of them would
+probably be left there where they might produce serious results. More
+than that. If the fly should feed on such infected material the typhoid
+germs would go on developing in the intestine of the fly and would be
+passed out with the feces in which they retain their virulence for some
+days. In other words, the too familiar "fly-specks" are not only
+disgusting, but may be a very grave source of danger. It will be seen
+that in this way several members of a community might become infected
+with the typhoid germs before anyone was aware that there was a case of
+typhoid or a "bacillus carrier" in the neighborhood.
+
+One more example out of the scores that might be cited to show how the
+fly may carry typhoid germs. They may enter the sick chamber in the home
+or in the hospital and there gain access to the typhoid germs. These
+they may carry to other parts of the house or to near-by houses, or the
+flies may light on passing carriages or cars and be carried perhaps for
+miles before they enter another house and contaminate the food there.
+
+These are hypothetical cases, but they illustrate what is taking place
+hundreds of times every season all over the world wherever typhoid fever
+and flies occur, and no country or race is known to be immune from
+typhoid, and the fly is found "wherever man is found."
+
+In the summer of 1898 a commission was appointed to investigate the
+prevalence of typhoid fever in the United States Army Concentration
+Camps. The following are some of the conclusions as reported by Dr.
+Vaughan:
+
+     "FLIES UNDOUBTEDLY SERVED AS CARRIERS OF THE INFECTION
+
+     "My reasons for believing that flies were active in the
+     dissemination of typhoid may be stated as follows:
+
+     "_a._ Flies swarmed over infected fecal matter in the pits and then
+     visited and fed upon the food prepared for the soldiers at the mess
+     tents. In some instances where lime had recently been sprinkled
+     over the contents of the pits, flies with their feet whitened with
+     lime were seen walking over the food.
+
+     "_b._ Officers whose mess tents were protected by means of screens
+     suffered proportionately less from typhoid fever than did those
+     whose tents were not so protected.
+
+     "_c._ Typhoid fever gradually disappeared in the fall of 1898, with
+     the approach of cold weather, and the consequent disabling of the
+     fly.
+
+     "It is possible for the fly to carry the typhoid bacillus in two
+     ways. In the first place, fecal matter containing the typhoid germ
+     may adhere to the fly and be mechanically transported. In the
+     second place, it is possible that the typhoid bacillus may be
+     carried in the digestive organs of the fly and may be deposited
+     with its excrement."
+
+In Dr. Daniel D. Jackson's report to the Merchants' Association of New
+York on the "Pollution of New York Harbor as a Menace to the Health by
+the Dissemination of Intestinal Diseases Through the Agency of the
+Common House-fly," he shows graphically that the prevalence of typhoid
+and other intestinal diseases is coincident with the prevalence of
+flies, and that the greatest number of deaths from such diseases occurs
+near the river front where the open or poorly constructed sewers scatter
+the filth where the flies can feed on it, or along the wharves with
+their inadequate accommodations and the resulting accumulation of filth.
+
+
+FLIES AND OTHER DISEASES
+
+Not only is the house-fly an important factor in the dissemination of
+typhoid fever, but it has been definitely shown that it is capable of
+transmitting several other serious diseases.
+
+The evidence that flies carry and spread the deadly germs of cholera is
+most conclusive. The germs may be carried on the body where they will
+live but a short time, or they may be carried in the alimentary canal
+where they will live for a much longer period and are finally deposited
+in the fly-specks where they retain their virulence for some time. Flies
+that had been allowed to contaminate themselves with cholera germs were
+allowed access to milk and meat. In both cases hundreds of colonies of
+the germs could later be recovered from the food. As with the typhoid
+germs milk seems to be a particularly good medium for the development of
+the cholera germs. In several of the experiments that have been made
+along this line the milk has been readily infected by the flies visiting
+it.
+
+Of course an outbreak of cholera is of rare occurrence in our country,
+but unfortunately this is not so in regard to some other intestinal
+diseases such as diarrhea and enteritis which annually cause the death
+of many children, especially bottle-fed babies. Those who have made
+close studies of the way in which these diseases are disseminated are
+convinced that the flies are one of the most important factors in their
+spread.
+
+It has long been observed that flies are particularly fond of sputum and
+will feed on it on the sidewalk, in the gutter, the cuspidor or wherever
+opportunity offers. It is well known, too, that the sputum of a
+consumptive contains myriads of virulent tubercular germs. A fly feeding
+and crawling over such material must necessarily get some of it on its
+body, and as it dries and the insect flies about the germs will be
+distributed through the air, possibly over our food. It has been shown
+that the excretion from a fly that has fed on tubercular sputum contains
+tubercular bacilli that may remain virulent for at least fifteen days.
+Thus we see again the danger that may lurk in the too familiar
+"fly-specks."
+
+Although it is generally supposed that the flea is solely responsible
+for the spread of the bubonic plague and no doubt is the principal
+distributing agent, the fact must not be overlooked that the house-fly
+may also be of considerable importance in this connection. Carefully
+planned experiments have shown that flies that have become infected by
+being fed on plague-infected material may carry the germs for several
+days and that they may die of the disease. During plague epidemics flies
+may become infected by visiting the sores on human or rat victims or by
+feeding on dead rats or on the excreta of sick patients, and an infected
+fly is always a menace should it visit our food or open wounds or sores.
+Anthrax bacilli are carried about and deposited by flies showing the
+possibility of the disease being spread in this way.
+
+Some believe that leprosy, smallpox and many other diseases are carried
+by the house-fly, so it is little wonder that it is fast losing its
+standing as a household companion and that we are beginning to regard it
+not only as a nuisance but as a source of danger which should no longer
+be tolerated in any community.
+
+Of course only a small per cent of the flies that visit our food in the
+dairies or market places or kitchens actually carry dangerous diseases,
+but they are all bred in filth and it is not possible without careful
+experiments or laboratory analysis to determine whether any of the germs
+among the millions that are on their bodies are dangerous or not. The
+chances that they may be are too great. The only safe way is to banish
+them all or to see that all of our food is protected from them.
+
+
+FIGHTING FLIES
+
+Screens and sticky fly-paper have their places and give some little
+relief in a well-kept house. But of what use is it to protect your food
+after it has entered your home if in the stores, in the market place, in
+the dairy barn, or dairy wagon, in the grocers' and butchers' cart, it
+has been exposed to contamination by hundreds of flies that have visited
+it.
+
+The problem is a larger one than keeping the house free from flies;
+larger but not more difficult, for the remedy is simple, effective,
+practicable and inexpensive. Destroy their breeding-places and you will
+have no flies. As the flies breed principally in manure the first
+remedial measure is to see that all manure is removed from the
+barn-yard at least once a week and spread over the fields to dry, for
+the flies cannot breed in the dry manure. If it is not practicable to
+remove it this often the manure should be kept in a bin that is closed
+so tight that no flies can get into it to lay their eggs. Sometimes the
+manure may be treated with some substance such as kerosene, crude oil,
+chlorid of lime, tobacco water or mixture of two or more of these and
+thus rendered unsuitable for the flies to breed in, but in general
+practice none of them has been found very satisfactory for the treatment
+is either not thorough enough or is too expensive of time and material.
+
+Outdoor privies and cesspools must be carefully attended to. The latter
+can be easily covered so no flies can get in and if the filthy and in
+every way dangerous pit under the privy be filled and the dry-earth
+closet substituted one of the greatest sources of danger, especially in
+the country and in towns with inadequate sewerage facilities, will be
+done away with. After these things are done there remain only the
+garbage cans and the rubbish heaps to look after.
+
+Of course your neighbor must keep his place clean too, for his flies are
+just as apt to come into your house as his, so the problem becomes one
+for the whole community.
+
+Almost all cities and many of the smaller towns have ordinances which
+if enforced would afford adequate protection from flies, but they are
+seldom if ever rigidly enforced and it yet remains for some enterprising
+town to be able to advertise itself as a "speckless town" as well as a
+"spotless town."
+
+
+AN EXPERT'S OPINION
+
+In a recent important bulletin issued by the Bureau of Entomology, Dr.
+L.O. Howard discusses the economic importance of several of the insects
+that carry disease. I wish to quote two or three paragraphs from the
+pages in which he discusses the house-fly or typhoid fly to show the
+opinion of this excellent authority in regard to this pest.
+
+     "Even if the typhoid or house fly were a creature difficult to
+     destroy, the general failure on the part of communities to make any
+     efforts whatever to reduce its numbers could properly be termed
+     criminal neglect; but since, as will be shown, it is comparatively
+     an easy matter to do away with the plague of flies, this neglect
+     becomes an evidence of ignorance or of a carelessness in regard to
+     disease-producing filth which to the informed mind constitutes a
+     serious blot on civilized methods of life."
+
+On another page:
+
+     "We have thus shown that the typhoid or house fly is a general and
+     common carrier of pathogenic bacteria. It may carry typhoid fever,
+     Asiatic cholera, dysentery, cholera morbus, and other intestinal
+     diseases; it may carry the bacilli of tuberculosis and certain eye
+     diseases. It is the duty of every individual to guard so far as
+     possible against the occurrence of flies upon his premises. It is
+     the duty of every community, through its board of health, to spend
+     money in the warfare against this enemy of mankind. This duty is as
+     pronounced as though the community were attacked by bands of
+     ravenous wolves."
+
+Again:
+
+     "A leading editorial in an afternoon paper of the city of
+     Washington, of October 20, 1908, bears the heading, 'Typhoid a
+     National Scourge,' arguing that it is to-day as great a scourge as
+     tuberculosis. The editorial writer might equally well have used the
+     heading 'Typhoid a National Reproach,' or perhaps even 'Typhoid a
+     National Crime,' since it is an absolutely preventable disease. And
+     as for the typhoid fly, that a creature born in indescribable filth
+     and absolutely swarming with disease germs should practically be
+     invited to multiply unchecked, even in great centers of population,
+     is surely nothing less than criminal."
+
+The whole bulletin (No. 78, Bureau of Entomology) should be read and
+studied by all who are interested in this subject.
+
+
+OTHER FLIES
+
+Occasionally other flies looking more or less like the house-fly are
+seen in houses. Some of these have the same type of sucking mouth-parts
+and have habits very similar to the house-fly, but as they are usually
+much less common and as nearly all that has been said in regard to the
+house-fly would apply equally well to them and as the same measures
+should be adopted in fighting them they need not be discussed further
+here.
+
+I have already called attention to the fact that a fly which looks very
+much like the house-fly is sometimes found in the house and will often
+bite severely. It has quite a different style of beak, one that is
+fitted for piercing so it may suck the blood of its victim (Fig. 51). As
+these flies often seem to be more persistent before a rain the weather
+prophet will tell you that "It is surely going to rain for the
+house-flies are beginning to bite."
+
+These stable-flies, as they are called, are great pests of cattle and
+horses in some sections. It is thought that they are important factors
+in the spread of some of the diseases of domestic animals, and their
+habit of sometimes attacking human beings makes it possible for them to
+carry certain disease germs from animals to man or from man to man.
+
+
+
+
+CHAPTER VI
+
+MOSQUITOES
+
+
+Mosquitoes are no more abundant now than they have been in the past, but
+when Linnæus in 1758 made his list of all the animals known to exist at
+that time he catalogued only six species of mosquitoes. Only a few years
+ago, 1901, Dr. Theobald of the British Museum published a book on the
+mosquitoes of the world in which he listed three hundred and forty-three
+kinds. Soon other volumes appeared, adding more species, and
+systematists everywhere have been describing new ones until now the
+total number of described species is probably over five hundred, more
+than sixty of which occur in the United States.
+
+This shows only one phase of the great interest that has been taken in
+the mosquitoes since the discovery of their importance as carriers of
+disease. Not only have they been studied from a systematic standpoint
+but an endless amount of work has been done and is being done in
+studying their development, habits, and structure until now, if one
+could gather together all that has been written about mosquitoes in the
+last ten or twelve years he would have a considerable library.
+
+[Illustration: FIG. 50--Pupa of house-fly with the end broken to allow
+the fly to issue.]
+
+[Illustration: FIG. 51--Head of stable-fly showing sharp piercing beak.]
+
+[Illustration: FIG. 52--Mass of mosquito eggs (_Theobaldia incidens_).]
+
+[Illustration: FIG. 53--Mosquito eggs and larvæ (_Theobaldia
+incidens_); two larvæ feeding on bottom, others at surface to breathe.]
+
+[Illustration: FIG. 54--Mosquito larvæ (_T. incidens_), dorsal view.]
+
+Those who are particularly interested in the group will find some of
+these books and papers easily accessible, so there may be given here
+only a brief summary of the more important facts in regard to the
+structure and habits of the mosquitoes in order that we may more readily
+understand the part that they play in the transmission of diseases and
+see the reasonableness of the recommendations in regard to fighting
+them.
+
+
+THE EGGS
+
+Mosquito eggs are laid in water or in places where water is apt to
+accumulate, otherwise they will not hatch. Some species lay their eggs
+in little masses (Fig. 52) that float on the surface of the water,
+looking like small particles of soot. Others lay their eggs singly, some
+floating about on the surface, others sinking to the bottom where they
+remain until the young issue. Some of the eggs may remain over winter,
+but usually those laid in the summer hatch in thirty-six to forty-eight
+hours or longer according to the temperature.
+
+
+THE LARVÆ
+
+When the larvæ are ready to issue they burst open the lower end of the
+eggs and the young wrigglers escape into the water. The larvæ are fitted
+for aquatic life only, so mosquitoes cannot breed in moist or damp
+places unless there is at least a small amount of standing water there.
+A very little will do, but there must be enough to cover the larvæ or
+they perish.
+
+The head of the larvæ of most species is wide and flattened. The eyes
+are situated at the sides, and just in front of them is a pair of short
+antennæ which vary with the different species.
+
+The mouth-parts too vary greatly according to the feeding habits. Some
+mosquito larvæ are predaceous, feeding on the young of other species or
+on other insects. These of course have their mouth-parts fitted for
+seizing and holding their prey. Most of the wrigglers, however, feed on
+algæ, diatoms, Protozoa and other minute plant or animal forms which are
+swept into the mouth by curious little brush-like organs whose movements
+keep a stream of water flowing toward the mouth.
+
+Another group containing the _Anopheles_ are intermediate between these
+two and have mouth-parts fitted for feeding on minute organisms as well
+as for attacking and holding other larger things.
+
+[Illustration: FIG. 55--Eggs, larvæ and pupæ of mosquitoes (_T.
+incidens_).]
+
+[Illustration: FIG. 56--Larva of mosquito (_T. incidens_).]
+
+[Illustration: FIG. 57--Mosquito larvæ and pupæ (_T. incidens_) with
+their breathing-tubes at the surface of the water.]
+
+[Illustration: FIG. 58--Anopheles larvæ (_A. maculipennis_) resting at
+the surface of the water.]
+
+A few kinds feed habitually some distance below the surface, others on
+the bottom, while still others feed always at the surface. With one or
+two exceptions, the larvæ must all come to the surface to breathe (Figs.
+53-57). Most species have on the eighth abdominal segment a rather long
+breathing-tube the tip of which is thrust just above the surface of the
+water when they come up for air. In this tube are two large vessels or
+tracheæ which open just below the tip of the tube and extend forward
+through the whole length of the body, giving off branches here and there
+that divide into still smaller branches until every part of the body is
+reached by some of the small divisions of this tracheal system that
+carries the oxygen to all the tissues. The length of the breathing-tube
+is correlated with the feeding-habits of the larvæ. _Anopheles_ larvæ
+which feed at the surface have very short tubes (Fig. 58), others that
+feed just below the surface have breathing-tubes as long or very much
+longer than the ninth abdominal segment. The last segment has at its tip
+four thin flat plates, the tracheal gills. These too are larger or
+smaller according to the habits of the larvæ. Those species that feed
+close to the surface and have the tip of the breathing-tube above the
+surface most of the time have very small tracheal gills, while those
+that feed mostly on the bottom have them well developed.
+
+When first hatched the larvæ are of course very small. If the weather is
+warm and the food is abundant they grow very rapidly. In a few days the
+outer skin becomes rather firm and inelastic so it will not allow
+further growth. Then a new skin forms underneath and the old skin is
+cast off. This process of casting off the old skin is called molting,
+and is repeated four times during the one, two, three or more weeks of
+larval life.
+
+
+PUPA
+
+With the fourth molt the active feeding larva changes to the still
+active but non-feeding pupa (Fig. 59). The head and thorax are closely
+united and a close inspection will reveal the head, antennæ, wings and
+legs of the adult mosquito folded away beneath the pupal skin. Instead
+of the breathing-tube on the eighth segment of the abdomen as in the
+larva, the pupa has two trumpet-shaped tubes on the back of the thorax
+through which it now gets its air from above the surface. The pupal
+stage lasts from two to five or six days or more. When the adult is
+ready to issue the pupal skin splits along the back and the mosquito
+gradually and slowly issues. It usually takes several minutes for the
+adult to issue and for its wings to become hard enough so it can fly. In
+the meantime, it is resting on the old pupal skin or on the surface of
+the water, where it is entirely at the mercy of any of its enemies that
+might happen along and is in constant danger of being tumbled over
+should the water not be perfectly smooth.
+
+[Illustration: FIG. 59--Mosquito pupæ (_T. incidens_) resting at the
+surface of the water.]
+
+[Illustration: FIG. 60--Mosquito pupa (_T. incidens_) with its
+breathing-tubes in an air bubble below the surface of the water.]
+
+[Illustration: FIG. 61--Mosquito larvæ and pupæ (_T. incidens_) resting
+at the surface of the water.]
+
+[Illustration: FIG. 62--A female mosquito (_T. incidens_); note the
+thread-like antennæ.]
+
+[Illustration: FIG. 63--A male mosquito (_T. incidens_); note the
+feathery antennæ.]
+
+
+THE ADULT
+
+The adult mosquito is altogether too familiar an object to need
+description, but it is necessary that we keep in mind certain particular
+points in regard to its structure, in order that we may better
+understand how it is that it is capable of transmitting disease.
+
+If we examine closely the antennæ of a number of mosquitoes that are
+bothering us with their too constant attentions we shall see that they
+all look very much alike (Fig. 62), small cylindrical joints bearing
+whorls of short fine hairs. But if we examine a number of mosquitoes
+that have been bred from a jar or aquarium we will find two types of
+antennæ, the one described above belonging to the female. The antennæ of
+the male (Fig. 63) are much more conspicuous on account of the whorl of
+dense, fine, long hairs on each segment. Another interesting difference
+in the antennæ is to be noted in the size of the first joint. In both
+sexes it is short and cup-shaped, but in the male it is somewhat larger.
+This basal segment contains a highly complex auditory organ which
+responds to the vibrations of the whorls of hairs on the other segments.
+Interesting experiments have shown that these hairs vibrate best to the
+pitch corresponding to middle C on the piano, the same pitch in which
+the female "sings." Of course mosquitoes and other insects have no voice
+as we ordinarily understand the word, but produce sound by the rapid
+vibration of the wings or by the passage of air through the openings of
+the tracheæ. The males and females are thus easily distinguished and, as
+we shall see later, this is of some importance for only the females can
+bite. The males and females differ in another way. Just below the
+antennæ and at the sides of the proboscis or beak is a pair of three-to
+five-jointed appendages, the maxillary palpi or mouth-feelers which in
+the females of most species are very short (Fig. 64) while in the males
+they are usually as long as the proboscis (Fig. 65). The females of
+_Anopheles_ and related forms have palpi quite as long as the males, but
+they are slender throughout while the male palpi are usually somewhat
+enlarged toward the tip and bear more or less conspicuous patches of
+rather long hairs or scales.
+
+[Illustration: FIG. 64--Head and thorax of female mosquito
+(_Ochlerotatus lativittatus_); the short maxillary palpi are just above
+the proboscis and below the thread-like antennæ.]
+
+[Illustration: FIG. 65--Head and thorax of male mosquito (_O.
+lativittatus_); the maxillary palpi are as long as the proboscis.]
+
+[Illustration: FIG. 66--Head of female mosquito (_Anopheles_), with
+mouth-parts separated to show the needle-like parts: _a_, _a_ antennæ;
+_b_, _b_, palpi; _c_, labrum; _d_, _d_, mandibles; _e_, hypopharynx;
+_f_, _f_, maxillæ; _g_, labium; _h_, labella. (After Manson.)]
+
+[Illustration: FIG. 67--Cross-section of proboscis of female (_a_) and
+male (_b_) mosquito. _lxe_, labrum-epipharynx; _mn_, mandibles; _mx_,
+maxillæ; _hp_, hypopharynx; _sal_, salivary duct; _li_, labium; _tr_,
+trachea; _mus_, muscles. (After Nuttall and Shipley.)]
+
+
+THE MOUTH-PARTS
+
+The mouth-parts of the mosquito are of course of particular interest to
+us. At first they appear to consist of a long slender beak or proboscis,
+but by dissecting and examining with a microscope we find this beak to
+be made up of several parts (Fig. 66). The labium, which is the largest
+and most conspicuous, is apparently cylindrical but is grooved above
+throughout its length. At the tip of the labium are the labellæ, two
+little lobes which serve to guide the piercing organs. Lying in this
+groove along the upper side of the labium are six very fine,
+sharp-pointed needles. The uppermost of these, the labrum-epipharynx, or
+labrum as we will call it, is the largest and is really a hollow tube
+very slightly open on its under side. Just below this is the
+hypopharynx, the lateral margins of which are very thin. Down through
+the median line of the hypopharynx runs a minute duct (Fig. 67, sal)
+which, though exceedingly small, is of very great importance, for
+through it is poured the saliva which may carry the malaria germs into
+the wound made when the mosquito bites. The other four needles consist
+of a pair of mandibles which are lance-shaped at the tip and a heavier
+pair of maxillæ, the tips of which are serrate on one edge.
+
+
+HOW THE MOSQUITO BITES
+
+When the female mosquito is feeding on man or any other animal the tip
+of the labium is placed against the surface and the six needles are
+thrust into the skin, the labellæ serving as guides. As they are thrust
+deeper and deeper the labium is bowed back to allow them to enter. As
+soon as the wound is made the insect pours out through the tube of the
+hypopharynx some of the secretion from the salivary glands and then
+begins to suck up the blood through the hollow labrum into the pharynx
+and on into the stomach.
+
+The mouth-parts of the male differ in some important respects from those
+of the female. The hypopharynx is united to the labium, the mandibles
+are wanting and the maxillæ are very much reduced so that the insect is
+unable to pierce the tough skin of animals. The male feeds on the juices
+of plants as do the females when they cannot get blood. It is not at all
+necessary for mosquitoes to have the warm blood of man or other animals.
+Comparatively few of them ever taste blood. They have been seen feeding
+on blossoms, ripe fruit, watermelons, plant juices, etc. They are very
+fond of ripe bananas and are fed on them in the laboratory when we wish
+to keep mosquitoes for experimental purposes.
+
+
+THE THORAX
+
+The middle part of the body, called the thorax, is really a strong box
+with heavy walls for the attachment of the powerful wing and leg
+muscles. The three pairs of legs are covered with hairs and scales, and
+their tips are provided with a pair of claws which vary somewhat in the
+different species. The wings (Fig. 68) are long and narrow with a
+characteristic venation. Along the veins and the margin of the wings are
+the scales which readily enable one to distinguish mosquitoes from other
+insects that may look much like them. In some species these scales are
+long and narrow, almost hair-like, in others they are quite broad and
+flat (Fig. 69). Just back of the wings is a pair of balancers, short
+thread-like processes knobbed at the end. These probably represent the
+second pair of wings with which most insects are provided, and seem to
+serve as balancers or orienting organs when the insect is flying. On the
+sides of the thorax are two small slit-like openings, the
+breathing-pores. These are the openings into the tracheal or respiratory
+system.
+
+
+THE ABDOMEN
+
+The long cylindrical abdomen is composed of eight segments. These are
+rather strongly chitinized above and below, but a narrow strip along the
+side is unchitinized. In this strip are situated the abdominal
+breathing-pores. The tip of the abdomen is furnished with a pair of
+movable organs, which in the male are variously modified and serve as
+clasping organs at mating time.
+
+
+THE DIGESTIVE SYSTEM
+
+The mouth-parts of the mosquito have just been described. It will be
+remembered that the labrum is provided with a groove. Through this the
+blood or other food is sucked up by means of a strong-walled pumping
+organ, the pharynx, situated in the head (Fig. 70). Just back of the
+pharynx is the esophagus which leads to the beginning of the stomach.
+Close to its posterior end the esophagus gives off three food
+reservoirs, two above and a single larger one below. In dissections
+these will often be seen to be filled with minute bubbles. The stomach
+reaches from the middle of the thorax to beyond the middle of the
+abdomen. At its posterior end are given off five long slender processes,
+the Malpighian tubules which are organs of excretion, acting like the
+kidneys of higher animals. The hindgut is that portion of the intestine
+from the stomach to the end of the body.
+
+[Illustration: FIG. 68--Wing of Mosquito (_O. lativittatus_).]
+
+[Illustration: FIG. 69--End of mosquito wing highly magnified to show
+the scales on the veins.]
+
+[Illustration: FIG. 70--Diagram to show the alimentary canal and
+salivary glands of a mosquito.]
+
+[Illustration: FIG. 71--Salivary glands of _Culex_ at right. _Anopheles_
+at left. (After Christophers.)]
+
+
+THE SALIVARY GLANDS
+
+Lying under the alimentary canal in the forward part of the thorax are
+the salivary glands. There are two sets of these, each having three
+lobes with a common duct which joins the duct from the other set a short
+distance before they enter the base of the hypopharynx. Each of these
+lobes is made up of a layer of secreting cells (Fig. 71) which produces
+the saliva that is poured into the wound as soon as the insect pierces
+the skin of the victim, and we shall see, too, that the malarial germs
+also collect in these glands to be carried by the saliva to the new
+host.
+
+
+EFFECTS OF THE BITE
+
+After a mosquito has bitten a person and withdrawn the stylets, a small
+area about the puncture whitens, then soon becomes pink and begins to
+swell, then to itch and burn. Some people suffer much more from the
+bites of mosquitoes than do others. For some such bites mean little or
+no inconvenience, indeed may pass wholly unnoticed, to others a single
+bite may mean much annoyance, and several bites may cause much
+suffering.
+
+After an hour or so the itching usually ceases, but in some cases it
+continues longer. In some instances little or no irritation is felt
+until some hours, sometimes as much as a day, after the bite. In such
+cases the effect of the bite is apt to be severe and to last for several
+days. Sometimes a more or less serious sore will follow a bite, probably
+due to infection of the wound by scratching. It is doubtless the saliva
+that is poured into the wound that causes the irritation. It is
+frequently asserted that if the mosquito is allowed to drink its fill
+and withdraw its beak without being disturbed no evil results will
+follow. Those who hold this theory say that the saliva that is poured
+into the wound is all withdrawn again with the blood if the mosquito is
+allowed to feed long enough. There may be some truth in this, but for
+most of us a bite means a hurt anyway and few will be content to sit
+perfectly still and watch the little pest gradually fill up on blood.
+
+It is not known just what the action of the saliva is, its composition
+or reaction on the tissues. It is generally supposed to prevent
+coagulation of the blood that is to be drawn through the narrow tube of
+the labrum. Others think that its presence causes a greater flow of
+blood to the wound. But the sad part of it is, for us at least, that it
+hurts and may cause malaria and possibly other diseases.
+
+
+HOW MOSQUITOES BREATHE
+
+Mosquitoes and other insects do not have any nostrils nor do they
+breathe through any openings on the head. Along the sides of the thorax
+and abdomen is a series of very minute openings known as the spiracles.
+Through these the air passes into a system of air-tubes, the tracheæ.
+There are two main trunks or divisions of the tracheæ just inside the
+body-wall and a number of shorter connecting trunks. From these larger
+vessels arise a great number of smaller ones which branch and subdivide
+again and again until all the tissues are supplied by these minute
+little air-tubes that carry the oxygen to all parts of the body and
+carry off the waste carbon dioxid. These air-tubes are emptied and
+filled by the contractions of the walls of the abdomen. When the
+body-wall contracts the air is forced out of the thin-walled trachea
+through the spiracles; when the pressure is removed they are refilled by
+the fresh air rushing in.
+
+
+THE BLOOD
+
+After a mosquito has been feeding on a man or some other animal it is
+often so distended that the blood shows rich and red through the thin
+sides of the walls of the abdomen. This, however, is the blood of the
+victim and not of the mosquito. The blood of insects is not red but pale
+yellowish or greenish. It is not confined in definite vessels, but fills
+all the space inside the body cavity that is not occupied by some of the
+tissues or organs. It bathes the walls of the alimentary canal and
+gathers there the nourishment which it carries to all parts of the body.
+It does not carry oxygen or collect the carbon dioxid as does the blood
+of higher animals. That work, as we have just seen, is done by the
+air-tubes. Above the alimentary canal, extending almost the whole length
+of the abdomen and thorax, is a thin-walled pulsating vessel, the heart.
+This consists of a series of chambers each communicating with the one in
+front of it by an opening which is guarded by a valve. When one of these
+chambers contracts it forces the blood that is in it forward into the
+next chamber which, in its turn, sends it on. As the walls relax the
+valves at the sides are opened and the blood that is in the body-cavity
+rushes in to fill the empty chamber. As these regular rythmical
+pulsations recur the blood is forced forward through the heart into the
+head where it bathes the organs there. We shall see in another chapter
+that the malarial parasite escapes from the walls of the stomach of the
+mosquito into the blood in the body-cavity and finally reaches the
+salivary glands. As the heart is constantly driving blood to this part
+of the body the parasites readily reach the glands from which they
+finally escape into the new host.
+
+[Illustration: FIG. 72--Heads of Culicinæ mosquitoes; _a_, male; _b_,
+female. (After Manson.)]
+
+[Illustration: FIG. 73--Heads of Anophelinæ mosquitoes; _c_, male; _d_,
+female. (After Manson.)]
+
+[Illustration: FIG. 74--Wing of _Anopheles maculipennis_.]
+
+[Illustration: FIG. 75--Wing of _Theobaldia incidens_.]
+
+[Illustration: FIG. 76--A non-malarial mosquito (_T. incidens_), male,
+standing on the wall.]
+
+[Illustration: FIG. 77--Female of same.]
+
+[Illustration: FIG. 78--A malarial mosquito (_A. maculipennis_), male,
+standing on the wall.]
+
+[Illustration: FIG. 79--Female of same.]
+
+
+CLASSIFICATION
+
+For our purpose it will not be necessary to try to give a system of
+classification of all the mosquitoes. Those interested in this phase of
+the subject will find several books and papers devoted wholly to it. It
+is quite important, however, that we know something about a few of the
+more familiar groups and kinds, especially those concerned in the
+transmission of diseases.
+
+
+THE ANOPHELES
+
+In pointing out the differences between male and female mosquitoes we
+noted that in one group, the genus _Anopheles_, both sexes have long
+maxillary palpi (Figs. 72, 73). This is the most important character
+separating this genus from the other common forms and as the
+_Anopheles_ are the malaria carriers it is important that this
+difference be remembered. Most of the members of this group have spotted
+wings (Fig. 74), but as some other common kinds also have spotted wings
+(Fig. 75) this character will not always be reliable. When an
+_Anopheles_ mosquito is at rest the head and proboscis are held in one
+line with the body and the body rests at a considerable angle to the
+surface on which it is standing. Other kinds rest with the body almost
+or quite parallel to the surface on which they are standing. So if you
+find a female mosquito with long mouth-palpi and spotted wings resting
+at an angle to the surface on which it stands you may be reasonably sure
+that it is an _Anopheles_ and therefore may be dangerous (Figs. 76, 77,
+78, 79).
+
+In the United States there are three species of
+_Anopheles_--_maculipennis_, _punctipennis_ and _crucians_--which are
+common in various localities, and one or two other species that so far
+as known are local or rare.
+
+The _Anopheles_ eggs are not laid in masses as are the eggs of many
+other mosquitoes, but are deposited singly on the surface of the water
+where they may be found often floating close together.
+
+[Illustration: FIG. 80--Egg of Anopheles, side view. (After Nuttall and
+Shipley.)]
+
+[Illustration: FIG. 81--Egg of Anopheles, dorsal view. (After Nuttall
+and Shipley.)]
+
+[Illustration: FIG. 82--Anopheles larvæ, the one to the right feeding.]
+
+[Illustration: FIG. 83--Anopheles larvæ, the one to the right feeding,
+the other just coming to the surface.]
+
+[Illustration: FIG. 84--Anopheles larva, dorsal view.]
+
+[Illustration: FIG. 85--Anopheles pupæ resting at surface of water.]
+
+The eggs (Figs. 80, 81) are elliptical in outline and are provided with
+a characteristic membranous expansion near the middle.
+
+The larvæ may be found at the proper season and in the localities where
+they are abundant in almost any kind of standing water, in clear little
+pools beside running streams, in the overflow from springs, in swamps
+and marshy lands, in rain-barrels or any other places or vessels where
+the water is quiet. They do not breed in brackish water. As they feed
+largely on the algæ or green scum on the surface of the water they are
+especially apt to be found where this is present. We have already noted
+that their positions in the water differ from that assumed by other
+species (Fig. 82).
+
+As the breathing-tube is very short the larvæ must come close to the
+surface to breathe, and when they are feeding we find them lying just
+under and parallel to the surface of the water with their curious round
+heads turned entirely upside down as they feed on the particles that are
+floating on the surface (Figs. 83, 84).
+
+The pupæ do not differ very much from the pupæ of other species although
+the breathing-tubes on the thorax are usually shorter and the creature
+usually rests with its abdomen closer to the surface, that is, it does
+not hang down from the surface quite as straight as do other forms (Fig.
+85).
+
+The adults may be found out of doors or in houses, barns or other
+outbuildings. They do not seem to like a draft and consequently will be
+more apt to frequent rooms or places where there is little circulation
+of air. Although they are usually supposed to fly and bite only in the
+evening or at night, they may occasionally bite in the daytime. One
+hungry female took two short meals from my arm while we were trying to
+get her to pose for a photograph one warm afternoon.
+
+The female passes the winter in the adult condition, hibernating in any
+convenient place about old trees or logs, in cracks or crevices in doors
+or out of doors. In the house they hide in the closets, behind the
+bureau, behind the head of the bed, or underneath it, or in any place
+where they are not apt to be disturbed. During a warm spell in the
+winter or if the room is kept warm they may come out for a meal almost
+any time.
+
+
+THE YELLOW FEVER MOSQUITO
+
+Ranking next in importance to _Anopheles_ as a disseminator of disease
+and in fact solely responsible for a more dreaded scourge, is the
+species of mosquito now known as _Stegomyia calopus_. While this species
+is usually restricted to tropical or semi-tropical regions it sometimes
+makes its appearance in places farther north, especially in summer
+time, where it may thrive for a time. The adult mosquito (Fig. 104) is
+black, conspicuously marked with white. The legs and abdomen are banded
+with white and on the thorax is a series of white lines which in
+well-preserved specimens distinctly resembles a lyre. These mosquitoes
+are essentially domestic insects, for they are very rarely found except
+in houses or in their immediate vicinity. Once they enter a room they
+will scarcely leave it except to lay their eggs in a near-by cistern,
+water-pot, or some other convenient place.
+
+Their habit of biting in the daytime has gained for them the name of
+"day mosquitoes" to distinguish them from the night feeders. But they
+will bite at night as well as by day and many other species are not at
+all adverse to a daylight meal, if the opportunity offers, so this habit
+is not distinctive. The recognition of these facts has a distinct
+bearing in the methods adopted to prevent the spread of yellow fever.
+There are no striking characters or habits in the larval or pupal stages
+that would enable us to distinguish without careful examination this
+species from other similar forms with which it might be associated. For
+some time it was claimed that this species would breed only in clean
+water, but it has been found that it is not nearly so particular, some
+even claiming that it prefers foul water. I have seen them breeding in
+countless thousands in company with _Stegomyia scutellaris_ and _Culex
+fatigans_ in the sewer drains in Tahiti in the streets of Papeete. As
+the larvæ feed largely on bacteria one would expect to find them in
+exactly such places where the bacteria are of course abundant.
+
+The fact that they are able to live in any kind of water and in a very
+small amount of it well adapts them to their habits of living about
+dwellings.
+
+So far as known the members of these two genera are the only two that
+are concerned in the transmission of disease in the United States. In
+other countries other species are suspected or proven disseminators of
+certain diseases, but these will be discussed in connection with the
+particular diseases in later chapters.
+
+
+OTHER SPECIES
+
+The many other species of mosquitoes that we have may be conveniently
+divided as to their breeding-habits into the fresh-water and the
+brackish-water forms. Among the fresh-water kinds some are found
+principally associated with man and his dwelling places, others live in
+the woods or other places and so are far less troublesome. Most of
+these do not fly far. Several of the species that breed in brackish
+water are great travelers and may fly inland for several miles. Thus the
+towns situated from one to three or four miles inland from the lower
+reaches of San Francisco Bay are often annoyed more by the mosquitoes
+that breed only in the brackish water on the salt marshes than they are
+by any of the fresh-water forms (Figs. 86, 87). The worst mosquito pest
+along the coast of the eastern United States and for some distance
+inland is a species that breeds in the salt marshes.
+
+
+NATURAL ENEMIES OF MOSQUITOES
+
+In combating noxious insects we learned long ago that often the most
+efficient, the easiest and cheapest way is to depend on their natural
+enemies to hold them in check. Under normal or rather natural conditions
+we find that they are usually kept within reasonable bounds by their
+natural enemies, but under the artificial conditions brought about by
+the settling and developing of any district great changes come about. It
+very often happens that these changes are favorable to the development
+of the noxious insects and unfavorable to the development of their
+enemies.
+
+A striking example and one to the point is afforded in the introduction
+of mosquitoes into Hawaii. Up to 1826 there were no mosquitoes on these
+islands. It is supposed that they were introduced about that time by
+some ships that were trading at the islands. Indeed it is claimed that
+the very ship is known that brought them over from Mexico.
+
+Once introduced they found conditions there very favorable to their
+development, plenty of standing water and few natural enemies to prey on
+them, so they increased very rapidly and gradually spread over all the
+islands of the group. This was the so-called night mosquito, _Culex
+pipiens_. Much later another species, _Stegomyia calopus_, just as
+annoying and much more dangerous was introduced and has also become very
+troublesome. We have a few species of top-minnows (Fig. 88) occurring in
+sluggish streams in the southern part of the United States that are
+important enemies of the mosquitoes of that region. A few years ago some
+of these were taken over to Hawaii and liberated in suitable places to
+see if they would not help solve the mosquito problem there. The fishes
+seem to be doing well. Already they are destroying many mosquito larvæ,
+and there are indications that they are going to do an important work,
+but of course can be depended on only as an aid.
+
+[Illustration: FIG. 86--Salt-marsh mosquito (_Ochlerotatus
+lativittatus_); male.]
+
+[Illustration: FIG. 87--Salt-marsh mosquito (_O. lativittatus_);
+female.]
+
+[Illustration: FIG. 88--Top-minnow (_Mollienisia latipinna_). (From
+Bull., 47 U.S. Fish Com.)]
+
+[Illustration: FIG. 89--Dragon-flies. (From Kellogg's Amer. Insects.)]
+
+On account of the various habits of both the larvæ and adults it will
+never be possible for any natural enemy or group of natural enemies
+effectively to control the mosquitoes of any region, but as certain of
+them are important as helpers they deserve to be mentioned.
+
+
+ENEMIES OF THE ADULTS
+
+Birds devour a few mosquitoes, the night-flying forms being particularly
+serviceable, but the number thus destroyed is probably so small as to be
+of little practical importance.
+
+The dragon-flies (Figs. 89, 90, 91) or mosquito hawks have long been
+known as great enemies of mosquitoes, and they certainly do destroy many
+of them as they are hawking about places where mosquitoes abound. Dr.
+J.B. Smith of New Jersey very much doubts their efficiency, but
+observations made by other scientific men would seem to indicate that
+they often devour large numbers of mosquitoes during the course of the
+day and evening.
+
+Spiders and toads destroy a few mosquitoes each night. Certain external
+and internal parasites destroy a few more, but the sum total of all of
+these agencies is probably not very considerable, for while the adults
+may have several natural enemies they are not of sufficient importance
+to have any appreciable effect on the number of mosquitoes in a badly
+infested region.
+
+
+ENEMIES OF THE LARVÆ AND PUPÆ
+
+The larvæ and pupæ on the other hand have many important enemies. Indeed
+under favorable conditions these may keep small ponds or lakes quite
+free from the pests. The predaceous aquatic larvæ of many insects feed
+freely on wrigglers. The larvæ of the diving beetles which are known as
+water-tigers are particularly ferocious and will soon destroy all the
+wrigglers in ponds where they are present (Fig. 92). Dragon-fly larvæ
+also feed freely on mosquito larvæ. Whirligig beetles are said to be
+particularly destructive to _Anopheles_ larvæ and many other insects
+such as water-boatmen, back-swimmers, etc., feed on the larvæ of various
+species. A few of these introduced into a breeding-jar with _Anopheles_
+larvæ will soon destroy all of them, even the very young bugs attacking
+larvæ much larger than themselves.
+
+It is interesting to note that the larvæ of some mosquitoes are
+themselves predaceous and feed freely on the other wrigglers that may
+chance to be in the same locality.
+
+[Illustration: FIG. 90--The young (nymph) of a dragon-fly. (From
+Kellogg's Amer. Insects.)]
+
+[Illustration: FIG. 91--The cast skin (exuvæ) of a dragon-fly nymph.]
+
+[Illustration: FIG. 92--Diving-beetles and back-swimmers. (From
+Kellogg's Amer. Insects.)]
+
+Various species of fish are, however, the most important enemies of the
+mosquitoes. Great schools of tide-water minnows (Fig. 93) are often
+carried over the low salt-marshes by the extreme high-tides and left in
+the hundreds of tide pools as the tide recedes. No mosquitoes can breed
+in a pool thus stocked with these fish. In the fresh-water streams and
+lakes there are several species of the top-minnows, sticklebacks (Fig.
+94), etc., that feed voraciously on mosquito larvæ and unless the grass
+or reeds prevent the fish from getting to all parts of the ponds or
+lakes very few mosquitoes can breed in places where they are present.
+
+Minute red mites such as attack the house-flies and other insects
+sometimes attack adult mosquitoes, but they are rarely very abundant.
+Parasitic roundworms attack certain species. Others suffer more or less
+from the attacks of various Sporozoan parasites.
+
+
+FIGHTING MOSQUITOES
+
+When mosquitoes are bothering us we usually begin by trying to kill the
+individual pests that are nearest to us. We try to crush them if they
+bite us; we screen the doors and windows to keep them from the house. In
+warmer countries the people are a little more hospitable and do not
+screen the mosquitoes out of the house entirely, but screen the beds for
+protection at night, and if the mosquitoes get too insistent during the
+day the bed makes a safe and comfortable retreat. All the mosquitoes in
+a room may be killed by fumigating with sulphur at the rate of two
+pounds to the thousand cubic feet of air-space. Pyrethrum is also used
+largely, but it only stupefies the mosquitoes temporarily instead of
+killing them. While in that condition they may be swept up and
+destroyed.
+
+Various substances are sometimes used as repellants by those who must be
+in regions where the mosquitoes are abundant. With many of these,
+however, "the cure is worse than the disease." Smudges are often built
+to the windward of a house or barn-yard and the smoke from a good
+smoldering fire will keep a considerable area quite free from
+mosquitoes. The man who can keep himself enveloped in a cloud of tobacco
+smoke will not be bothered by mosquitoes. Oil of pennyroyal, oil of tar
+or a mixture of these with olive oil, and various other concoctions are
+sometimes smeared over the face and hands. These will furnish protection
+as long as they last. Dr. Smith says that he has found oil of citronella
+quite effective and of course less objectionable than the other things
+usually used. Care should be taken not to get it in the eyes. An
+ointment made of cedar oil, one ounce; oil of citronella, two ounces;
+spirits of camphor, two ounces, is said to make a good repellant and is
+effective for a long time.
+
+[Illustration: FIG. 93--Killifish (_Fundulus heteroliatus_). (From
+Bull. 47, U.S. Fish Com.)]
+
+[Illustration: FIG. 94--Stickleback (_Apeltes quadracus_). (From Bull.
+47, U.S. Fish Com.)]
+
+[Illustration: FIG. 95--An old watering trough, an excellent
+breeding-place for mosquitoes.]
+
+
+FIGHTING THE LARVÆ
+
+All of the efforts directed against the adult mosquitoes are usually of
+little avail in decreasing the number in any region. It is comparatively
+easy, however, to fight them successfully in the larval stage. We have
+seen that standing water is absolutely necessary for mosquitoes to breed
+in. This makes the problem much simpler than if they could breed in any
+moist places such as well-sprinkled lawns, a shady part of the garden,
+etc. The whole problem of successful campaigns against the mosquitoes
+resolves itself into the problem of finding and destroying or properly
+treating their breeding-places. We have seen how certain kinds, such as
+the yellow fever mosquito, are "domestic" species. They never go far
+from their breeding-places. If a house is infected by one of these
+species the immediate premises should be searched for the source.
+Cisterns, rain-barrels, sewer-traps, cesspools, tubs or buckets of water
+or old tin cans in out-of-the-way corners, are all suitable places for
+them to breed in. Cisterns and rain-barrels should be thoroughly
+screened so that no mosquitoes can get in or out, or the surface should
+be covered with a film of kerosene which will kill all the larvæ in the
+water when they come to the surface to breathe, and will also kill the
+females when they come to deposit their eggs. The vent to open cesspools
+should be thoroughly screened or the surface of the water kept well
+covered with oil. Water standing in any vessels in the yards should be
+emptied every week or ten days and the old tin cans destroyed or hauled
+away. In fighting these domestic species you need be concerned only with
+your own yard and that of your near-by neighbors. Other species, while
+also rather local in their distribution, fly much farther than the
+really domestic ones. In fighting these the region for a considerable
+distance around must be taken into consideration. Watering-troughs (Fig.
+95) that are left filled from week to week, the overflow from such
+places, and the tracks made in the mud round about them (Fig. 96), small
+sluggish streams, irrigating ditches, and small ponds or lakes not
+supplied with fish are excellent breeding-places for several species of
+mosquitoes including _Anopheles_ and others. The remedy at once suggests
+itself. The watering-trough can be emptied and renewed every week during
+the summer time, the overflow can be taken care of in a ditch that will
+lead it away from the trough to where it will sink into the ground, the
+banks of the streams or ponds or lakes can be cleared in such a way that
+fish can get to all parts of the water; most of the small ponds can be
+drained or their surface may be covered over with a thin film of
+kerosene. This is best applied as a spray; one ounce to fifteen square
+feet will suffice. If the oil is simply poured over the surface more
+will be required.
+
+The fighting of the species that breed on the extensive salt-marshes in
+many regions is a larger and more difficult problem, but as it is a
+matter that usually concerns large communities, sometimes whole states,
+it can be dealt with on a larger scale. The very excellent results that
+have been accomplished in New Jersey and on the San Francisco peninsula,
+and in a smaller way in other places, show what may be done if the
+community goes about the fight in an intelligent manner. In the fight in
+New Jersey hundreds of acres of tide-lands have been drained so that
+they no longer have tide pools standing where the mosquitoes may breed.
+When it is impracticable to drain them the pools may be sprayed
+occasionally with kerosene.
+
+The value of the land that is reclaimed by a good system of draining is
+often enough to pay many times over the cost of draining, thus the
+mosquitoes are gotten rid of and the land enhanced in value by a single
+operation.
+
+
+
+
+CHAPTER VII
+
+MOSQUITOES AND MALARIA
+
+
+Ever since the beginning of history we have records of certain fevers
+that have been called by different names according to the people that
+were affected. As we study these names and the various writings
+concerning the fevers we find that a great group of the most important
+of them are what we to-day know as malarial fevers. Not only are these
+ills as old as history but they have been observed over almost the
+entire inhabited earth. There are certain regions in all countries where
+malaria does not occur, but almost always it will be found that other
+regions near by are infected and it very often happens that these
+infected regions are the most profitable parts of the land, the places
+where water is plentiful and vegetation is luxuriant. Indeed the
+coincidence of these two things, low-lying lands with an abundance of
+water, particularly standing water, and malaria has always been noted
+and gave rise to the earliest theories in regard to the cause of the
+disease.
+
+For instance, we find some of the very early writers emphasizing the
+point that swampy localities should be avoided for they produce animals
+that give rise to disease, or that the air is poisoned by the breath of
+the swamp-inhabiting animals.
+
+These views of the origin of the fever prevailed until about the
+beginning of the eighteenth century when the recently discovered
+microscope began to reveal the various kinds of animalculæ to be found
+in decaying material.
+
+In 1718 Lancisi held that the myriads of insects, particularly gnats or
+mosquitoes, that arose from such swampy regions might carry some of
+these poisonous substances and by means of their proboscis introduce
+them into the bodies of the people, and although he had made no
+experiments to test the assumption he did not consider it impossible
+that such insects might also introduce the smallest animalculæ into the
+blood. It took almost two centuries of study and investigation before
+this guess was proved to be right.
+
+One reason why the mosquitoes were not earlier associated with these
+diseases was that all who investigated the matter at all turned their
+attention to the bad condition of the air in these swampy regions.
+Malaria means bad air. We all know that we can see the mists arising
+from such regions, particularly in the evening or at night, and as
+exposure to these mists very often meant an attack of malaria they were
+naturally supposed to be the cause of the disease. So for a long time
+the whole attention of investigators was turned toward studying and
+analyzing these vapors, and various experiments were made which seemed
+to show conclusively that the malaria was caused only by these
+emanations. The investigations even went so far that the exact germs
+that were supposed to cause the fever were separated and experimented
+with.
+
+
+THE PARASITE THAT CAUSES MALARIA
+
+The blood had been studied time and again and the characteristic
+appearance of the blood of a malarial patient was well known. In 1880
+Laveran, a French army surgeon in Algiers, began to study the blood of
+such patients microscopically and soon was able to demonstrate the
+parasite that caused the disease. His discoveries were not readily
+accepted, but other investigations soon confirmed his observations and
+the fact was gradually firmly established. Not until recently, however,
+did this distinguished physician receive a full recognition of his work.
+A few years ago he was awarded the Nobel prize for medicine, perhaps the
+highest honor that can be bestowed on any physician. It is interesting,
+too, to note in this connection that it was another French surgeon who
+in 1840 discovered that sulphate of quinine is a specific for malaria.
+
+[Illustration: FIG. 96--Horse and cattle tracks in mud filled with
+water; good breeding-places for Anopheles.]
+
+[Illustration: FIG. 97--A malarial mosquito (_Anopheles maculipennis_);
+male.]
+
+[Illustration: FIG. 98--A malarial mosquito (_A. maculipennis_);
+female.]
+
+The next important step was made in 1885 by Golgi, an Italian, who
+studied the life-history of the parasite in the blood and distinguished
+the three forms which cause the three most familiar kinds of malarial
+fevers, the tertian, the quartan and the remittent types. From this time
+on this parasite has been studied by physicians of many nationalities
+and the whole course of its life-history worked out. In order that we
+may understand how it was that mosquitoes were determined to be the
+means of disseminating this parasite we will discuss first its
+life-history in the human blood.
+
+The parasites that cause the malarial fevers are Sporozoans and belong
+to the genus _Plasmodium_. Other names such as _Hæmamoeba_ and
+_Laverania_ have been used for them, but the term _Plasmodium_ is the
+one now most commonly employed. The three most common species are
+_vivax_, _malariæ_ and _falciparum_, causing respectively the tertian,
+quartan and remittent fevers.
+
+
+LIFE-HISTORY OF PARASITE
+
+The life-history of all of these is very similar, the principal
+difference being in the length of time it takes them to sporulate. Let
+us begin with the parasite after it has been introduced into the blood
+and trace its development there. At first it is slender and rod-like in
+shape. It has some power of movement in the blood-plasm. Very soon it
+attacks one of the red blood-corpuscles and gradually pierces its way
+through the wall and into the corpuscle substance (Fig. 99); here it
+becomes more amoeboid and continues to move about, feeding all the
+time on the corpuscle substance, gradually destroying the whole cell. As
+the parasite feeds and grows there is deposited within its body a
+blackish or brownish pigment known as melanin.
+
+During the time that the parasite is feeding and growing it is also
+giving off waste products, as all living forms do in the process of
+metabolism, but as the parasite is completely inclosed in the corpuscle
+wall these waste products cannot escape until the wall bursts open.
+After about forty hours if the parasite is _vivax_ or about sixty-five
+hours if it is _malariæ_ it becomes immobile, the nucleus divides again
+and again and the protoplasm collects around these nuclei, forming a
+number of small cells or spores, as they are called. In about
+forty-eight or seventy-two hours, depending on whether the parasite is
+_vivax_ or _malariæ_ the wall of the corpuscle bursts and all these
+spores with the black pigment and the waste products that have been
+stored away within the cell are liberated into the blood-plasm.
+
+[Illustration: FIG. 99--Diagram to illustrate the life-history of the
+malarial parasite. 1 is a red blood-corpuscle, 2 to 7 shows the
+development of the parasite in the corpuscle, _a_ _b_ _c_ _d_ and _a´_
+_b´_ _c´_ and _e_ the development of the parasite in the stomach of the
+mosquito, _f_ _g_ _h_ _i_ the development in the capsule on the outer
+wall of the stomach of the mosquito, _k_ in the salivary gland.]
+
+[Illustration: FIG. 100--Malarial mosquito (_A. maculipennis_) on the
+wall.]
+
+[Illustration: FIG. 101--Malarial mosquito (_A. maculipennis_) standing
+on a table.]
+
+These spores are round or somewhat amoeboid and are carried in the
+blood for a short time. Very soon, however, each one attacks a new red
+corpuscle and the process of feeding, growth and spore-formation
+continues, taking exactly the same time for development as in the first
+generation, so every forty-eight hours in the case of the _vivax_, and
+every seventy-two hours in the case of the _malariæ_ a new lot of these
+spores and the accompanying waste products are thrown out into the
+blood. Thus in a very short time many generations of this parasite occur
+and thousands or hundreds of thousands of the red-blood corpuscles are
+destroyed, leaving the patient weak and anemic. It will be seen, too,
+that the recurrence of the chills and fevers is simultaneous with the
+escaping of the parasites from the blood-corpuscles, together with the
+waste products of their metabolism.
+
+These waste products are poisonous, and it is believed that this great
+amount of poison poured into the blood at one time causes the regular
+recurring crisis. Zoölogists well know that this process of asexual
+reproduction, _i. e._, reproduction without any conjugation of two
+different cells, cannot go on indefinitely, and those who were studying
+the life-cycle of these parasites were at a loss to know where the
+sexual stage took place. In the meantime studies of other parasites more
+or less closely related to _Plasmodium_ showed that the sexual stage
+occurred outside the vertebrate host. The remarkable work of Dr. Smith
+on the life-history of the germ that causes the Texas fever of cattle
+had a strong influence in directing the search for this other stage of
+the malarial parasite. Another thing that indicated that this sexual
+generation must take place outside the body of the vertebrate host was
+the fact that the investigators found that the parasites in certain of
+the cells did not sporulate as did the others. When these individuals
+were drawn from the circulation and placed on a slide for study it was
+found that they would swell up and free themselves from the inclosing
+corpuscle and some of them would emit long filaments which would dart
+away among the corpuscles.
+
+Many men have worked on this problem, but perhaps the most credit for
+its solution will always be given to Sir Patrick Manson, the foremost
+authority on tropical diseases, and to Ronald Ross, a surgeon in the
+English army. There is no more interesting and inspiring reading than
+that which deals with the development of the hypothesis by Manson and
+the persistent faith of Ross in the correctness of this theory, and his
+continuous indefatigable labors in trying to demonstrate it. It was an
+important piece of scientific work, and shows what a man can do even
+when the obstacles seem insurmountable.
+
+
+THE PARASITE IN THE MOSQUITO
+
+Briefly stated again, the problem was this: We have here a parasite in
+the blood which behaves as do many other forms of life. Some of these
+parasites do not go on with their development until they are removed
+from the circulation. Now, how are they thus removed from the
+circulation under normal conditions? This must first be solved before
+the still greater and more important problem of how the parasite gets
+from one human host to another can be taken up. In studying this over
+Manson reasoned that certain suctorial insects were the agencies through
+which blood was most commonly removed from the circulation and he
+ventured the guess that this change in the parasite that may be seen
+taking place on the slide under the microscope, normally takes place in
+the stomach of some insect that sucks man's blood. Ross was greatly
+impressed with the theory and began his long and apparently hopeless
+task of finding these parasites in the stomach of some insect. When we
+remember that they are so minute that they can only be seen by the use
+of the highest power of the microscope we can realize something of the
+magnitude of the task. Ross, who was at that time stationed in India,
+selected the mosquito as the most likely of the insects to be the host
+that he was looking for. For over two and one-half years he worked with
+entirely negative results, for after examining thoroughly many thousands
+of mosquitoes he found no trace of the parasite.
+
+Practically all his work was done on the most common mosquito of the
+region, a species of _Culex_. But one day a friend sent him a different
+mosquito, one with spotted wings, and in examining it he was interested
+to note certain oval or round nodules on the outer walls of the stomach.
+On closer examinations he found that each of these nodules contained a
+few granules of the coal-black melanin of malarial fever. Further
+studies and experiments showed that these particular cells could always
+be found in the walls of the stomach of this particular species of
+mosquito a few days after it had bitten a malarial patient. This
+epoch-making discovery was made in 1898. Ross was detailed by the
+English government to devote his whole time to the further solution of
+the problem, and after two years more of careful experimentation and
+study was able to give a complete life-history of this parasite. His
+experiments have been repeated many times, and the conclusions he
+arrived at are as undeniable as any of the known facts of science.
+
+The whole life-history as we now know it can be summed up as follows:
+The parasites develop within the circulation but certain of them seem to
+wander about and do not go on with their development there. When these
+particular parasites are taken into the stomach of most mosquitoes they
+are digested with the rest of the blood. But when they are taken into
+the stomach of a mosquito belonging to the genus _Anopheles_ or other
+closely related genera they are not digested but go on with their
+development, conjugation and fertilization taking place, resulting in a
+more elongated form which makes its way through the walls of the stomach
+on the outside of which are formed the little nodules discovered by Ross
+on his mosquitoes. Within these nodules further division and development
+takes place until finally the nodule is burst open and many thousand
+minute rod-like organisms, sporozoites, are turned loose into the
+body-cavity of the mosquito. Owing to some unknown cause these little
+organisms are gathered together in the large vacuolated cells of the
+salivary glands of the mosquito, and when the mosquito bites a man or
+any other animal they pour down through the ducts with the secretion and
+are thus again introduced in the circulation.
+
+The nodules or cysts on the walls of the stomach of the mosquito may
+contain as many as ten thousand sporozoites, and as many as five hundred
+cysts may occur on a single stomach.
+
+It takes ten, twelve or more days from the time the parasites are taken
+into the stomach of the mosquito before they can go through their
+transformations and reach the salivary gland, the time depending on the
+temperature. So it is ten or twelve days or sometimes as much as
+eighteen or twenty days from the time an _Anopheles_ bites a malarial
+patient before it is dangerous or can spread the disease. On the other
+hand, the sporozoites may lie in the salivary gland alive and virulent
+for several weeks. It does not give up all the parasites at one time, so
+that three or four or more people may be affected by a single mosquito.
+
+It is well known that two parasites may often be seen in the same
+corpuscle. This is often simply a case of multiple infection, but Dr.
+Craig has very recently shown that under certain conditions two
+individuals may enter the same corpuscle and conjugate and the resulting
+individual will be resistant to quinine and may remain latent in the
+spleen or bone marrow for a long time. Under favorable conditions it
+may again begin the process of multiplication and the patient will
+suffer a relapse.
+
+
+SUMMARY
+
+Now let us sum up some of the reasons why we believe that the malaria
+fever can be transmitted only through the agency of mosquitoes. First,
+we know the life-history of the parasite, it has been studied in both of
+its hosts. Attempts have been made to rear it in other hosts but without
+avail, and we know from the general relations of the parasite that it
+must have this sexual as well as the asexual generations. Second, in
+some regions which would seem to be malarial, that is, where the
+miasmatic mists arise, no malaria occurs. Why? Usually it can be
+definitely shown that no _Anopheles_ occur there. Other mosquitoes may
+be there in abundance, but if no _Anopheles_, there is no malaria. In
+certain regions this is well demonstrated. The west coast of Africa is
+one of the worst pest-holes of malaria and _Anopheles_. The east coast
+has no malaria and no _Anopheles_. In many islands the same condition
+exists. On the other hand, the Fiji Islands have _Anopheles_ but no
+malaria. No malaria has ever been introduced there to infect the
+mosquitoes. In the same way _Stegomyia_ occurs in some of the South Sea
+islands and yet there is no yellow fever there.
+
+
+EXPERIMENTS
+
+We may review, too, a few of the classic experiments that have served to
+show that malaria can be contracted in no other way than through the
+bite of the mosquito.
+
+For many years Grassi, an Italian, devoted almost his whole time to the
+study of malaria. In 1900 he received permission from the government to
+experiment on the employees of a piece of railroad that was being built
+through a malarial region. This was divided for the purpose of the
+experiment into three sections, a protected zone in the middle and an
+unprotected zone at each end.
+
+Those working in the protected zone had their houses completely screened
+and no one was allowed out of doors after sunset except they were
+protected with veils and gloves. Early in the season they were all given
+doses of quinine to prevent auto-infection. In the unprotected zone no
+screens were used and every one was allowed to go without special
+protection. The result for the summer was that there were no new cases
+of fever in the protected zone. In the unprotected zones practically all
+had the fever as usual.
+
+[Illustration: FIG. 102--Salt-marsh mosquito (_O. lativittatus_)
+standing on a table.]
+
+[Illustration: FIG. 103--Anopheles hanging from the ceiling.]
+
+In the same year two English physicians, Sambon and Low, went to Italy
+where they built a cabin in one of the marshes noted as being a malaria
+pest-hole. The house was thoroughly screened so that no mosquitoes could
+enter, but the windows were always open so as to admit the air freely
+day and night. Here they lived for three months, out of doors as much as
+they pleased during the day but inside where they were protected from
+the mosquitoes at night. No quinine was used and no fever developed,
+although all about them other people were having the fever as usual.
+
+Another English physician who had not been in malarial regions allowed
+himself to be bitten by infected mosquitoes sent from a malarial
+locality. In due time he developed the fever. Many other experiments
+made in various places might be cited. The results have all been
+practically the same. To-day the soldiers of many civilized nations are
+required to protect themselves from mosquitoes because it has been found
+that it pays. Disease has always been a worse terror than bullets in any
+war, and we are fast learning that the great loss from diseases
+heretofore considered unavoidable may be very largely eliminated by
+proper sanitary arrangements and protection from noxious insects.
+
+
+
+
+CHAPTER VIII
+
+MOSQUITOES AND YELLOW FEVER
+
+
+Yellow fever is a disease, principally of seaport towns, from which the
+United States has suffered more than any other country. It is endemic
+only in tropical regions but is often carried to subtropical, sometimes
+even to temperate zones where, if the proper mosquitoes exist, it may
+rage until frost.
+
+Vera Cruz, Havana, Rio de Janeiro, and the west coast of Africa were
+long regarded as permanent endemic foci, the disease appearing there in
+epidemic form from time to time, often spreading to other ports in more
+or less close communication with such places. In the United States the
+Gulf states have been the greatest sufferers from the disease, although
+it has spread as far as Baltimore, Philadelphia and Washington, where at
+rare intervals it was most serious, abating its ravages only when frost
+came.
+
+The last severe outbreak occurred in New Orleans in 1905 when eight
+thousand cases and nine hundred deaths occurred. At that time there was
+waged one of the most remarkable warfares against death in its most
+terrifying form that the world has ever known. And, thanks to the
+achievements of science, particularly to the investigations of three
+men, one of whom gave his life to the cause, the fight was successful
+and this dreadful outbreak was checked just at the time when according
+to all precedent it should have been at its height.
+
+This result which at other times and under other conditions would have
+been considered miraculous was achieved not by the usual custom of
+isolation, quarantine, etc., but by a direct, we may almost say hand to
+hand, conflict with mosquitoes: the mosquitoes belonging to a particular
+genus and species, _Stegomyia calopus_ (_fasciata_).
+
+Before taking up a discussion of this achievement in New Orleans let us
+consider first the work of the men that made such results possible.
+
+For many years the cause and methods of dissemination of this disease
+had been a puzzle to physicians and scientists. Very early it was
+believed that it might be transmitted through the air, and the fact that
+infection usually occurred in the vicinity of the water and in the
+tropics or in midsummer led to the belief that the disease was due to
+fermentation. This theory received strong support in the fact that
+serious outbreaks of the fever often followed the coming into port of
+vessels from the tropics with the water in their holds in an offensive
+condition. When it was discovered that bacteria were the cause of
+fermentation and also of many diseases this theory was considered
+abundantly proven. From time to time, announcements have been made that
+the particular species of bacteria that causes the disease has been
+isolated, but there has always been something lacking in the final
+proof.
+
+Yellow fever has always been regarded as a very highly contagious as
+well as infectious disease, and the utmost precaution has been taken to
+isolate the patients when possible and in recent years strict
+quarantines have been established against infected localities and no
+person or commerce or even the mails were allowed to come from such
+places without thorough fumigations. But all these things proved
+unsatisfactory. The disease could not ordinarily be checked by simply
+isolating the patients. Many people became sick without ever having been
+near a yellow fever patient, while others worked in direct daily contact
+with the disease and did not suffer from it. Those who had once had it
+and recovered became practically immune, rarely suffering from a second
+attack. Negroes may suffer from the disease, but are usually regarded as
+practically immune.
+
+[Illustration: FIG. 104--Yellow-fever mosquito (_Stegomyia calopus_).
+(R. Newstead, del.)]
+
+It was early observed, too, that the danger zone might be quite well
+defined and that outside this zone one would be safe. More than a
+century ago the British troops and other inhabitants of Jamaica found
+that by retreating to the mountains during the warm weather the
+non-immunes could escape the fever. It was also observed that those who
+slept on the first floor were more apt to take the disease than those on
+the second floor.
+
+
+THE YELLOW FEVER COMMISSION
+
+In 1900, during the American occupation of Cuba, yellow fever became
+very prevalent there. A board of medical officers was ordered to meet in
+Havana for the purpose of studying the disease under the favorable
+opportunities thus afforded. This board, which came to be known as the
+Yellow Fever Commission, was composed of Drs. Walter Reed, James
+Carroll, Jessie W. Lazear and Aristides Agramonte of the United States
+Army. Agramonte was a Cuban and an immune, the others were non-immunes.
+Dr. Manson in his lectures on Tropical Medicines says of them:
+
+     "I cannot pass on, however, to what I have to say in connection
+     with this work without a word of admiration for the insight, the
+     energy, the skill, the courage, and withal the modesty and
+     simplicity of the leader of that remarkable band of workers. If any
+     man deserved a monument to his memory, it was Reed. If any band of
+     men deserve recognition at the hands of their countrymen, it is
+     Reed's colleagues."
+
+Their first work was to determine whether any of the germs that had been
+claimed to be the cause of yellow fever were really responsible for the
+disease. _Bacillus icteroides_ that for some time and by some
+investigators had been named as the offender was particularly
+investigated, but was proved to be a secondary invader only.
+
+Dr. Charles Finlay of Havana had been claiming for some years that the
+yellow fever was transmitted by means of the mosquito and possibly by
+other insects also. He even claimed to have proved this theory
+experimentally. We know now, however, that there must have been errors
+in his experiments and that his patients became infected from sources
+other than those he was dealing with.
+
+The Yellow Fever Commission decided to put this theory to the test and
+secured a number of volunteers for the experiments. The first thing was
+to let an infected mosquito bite some non-immune person. How this was
+done and the results, may be told in Dr. Carroll's own words.
+
+
+EXPERIMENTS
+
+     "Two separate lines of work now presented: one, the study of the
+     bacterial flora of the intestine and anaërobic cultures from the
+     blood and various organs; the other, the theory of the transmission
+     of the disease by the mosquito, which had been advanced by Dr.
+     Carlos Finlay in 1881. After due consideration it was decided to
+     investigate the latter first. Then arose the question of the
+     tremendous responsibility involved in the use of human beings for
+     experimental purposes. It was concluded that the results
+     themselves, if positive, would be sufficient justification of the
+     undertaking. It was suggested that we subject ourselves to the same
+     risk and this suggestion was accepted by Dr. Reed and Dr. Lazear.
+     It became necessary for Dr. Reed to return to the United States and
+     the work was begun by Dr. Lazear, who applied infected mosquitoes
+     to a number of persons, himself included, without result. On the
+     afternoon of July 27, 1900, I submitted myself to the bite of an
+     infected mosquito applied by Dr. Lazear. The insect had been reared
+     and hatched in the laboratory, had been caused to feed upon four
+     cases of yellow fever, two of them severe, and two mild. The first
+     patient, a severe case, was bitten twelve days before; the second,
+     third and fourth patients had been bitten six, four and two days
+     previously, and were in character mild, severe and mild
+     respectively. In writing to Dr. Reed that night of the incident, I
+     remarked jokingly that if there was anything in the mosquito
+     theory, I should have a good dose. And so it happened. After having
+     slight premonitory symptoms for two days, I was taken sick on
+     August 31, and on September 1, I was carried to the yellow fever
+     camp. My life was in the balance for three days, and my chart shows
+     that on the fifth, sixth and seventh days my urine contained
+     eighth-tenths and nine-tenths of moist albumin. On the day I was
+     taken sick, August 31, 1900, Dr. Lazear applied the same mosquito,
+     with three others, to another individual who suffered a
+     comparatively mild attack and was well before I had left my bed. It
+     so happened that I was the first person in whom the mosquito was
+     proved to convey the disease.
+
+     "On the eighteenth of September, five days after I was permitted to
+     leave my bed, Dr. Lazear was stricken, and died in convulsions just
+     one week later, after several days of delirium with black vomit.
+     Such is yellow fever.
+
+     "He was bitten by a stray mosquito while applying the other insects
+     to a patient in one of the city hospitals. He did not recognize it
+     as a _Stegomyia_, and thought it was a _Culex_. It was permitted to
+     take its fill and he attached no importance to the bite until after
+     he was taken sick, when he related the incident to me. I shall
+     never forget the expression of alarm in his eyes when I last saw
+     him alive in the third or fourth day of his illness. The spasmodic
+     contractions of his diaphragm indicated that black vomit was
+     impending, and he fully appreciated their significance. The
+     dreaded vomit soon appeared. I was too weak to see him again in
+     that condition, and there was nothing that I could do to help him.
+
+     "Dr. Lazear left a wife and two young children, one of whom he had
+     never seen."
+
+These experiments and many others like them conducted on soldiers and
+Spanish immigrants proved that this particular mosquito would transmit
+the disease under certain conditions.
+
+1. The mosquito must bite the patient during the first three days of the
+fever; after that a yellow fever patient cannot infect a mosquito.
+
+2. A period of twelve days must elapse before the mosquito is able to
+infect another person. After that she may infect anyone she may bite;
+that is, the germs remain virulent during the rest of the mosquito's
+life. The French Yellow Fever Commission working in Rio de Janeiro claim
+that the first generation of offspring from such an infected mosquito is
+capable of causing the disease after they are fourteen days in the adult
+condition.
+
+The next step was to ascertain whether the disease could be contracted
+in any other way than by the bites of infected mosquitoes. A camp named
+Camp Lazear was established and the following tests made: A
+mosquito-proof building of one room was completely divided by a wire
+screen from floor to ceiling. In one room fifteen mosquitoes that had
+previously bitten yellow fever patients and had undergone the proper
+period of incubation were liberated. In this room a non-immune exposed
+himself so that he was bitten by several of the insects. A little later
+the same day and again the next day the mosquitoes were allowed to feed
+on him for a few minutes. Five days later, the usual incubation period,
+he developed yellow fever.
+
+At the same time that he entered the building two other non-immunes
+entered the other compartment where they slept for eighteen nights
+separated from the mosquitoes by the wire screen. They showed no signs
+of taking the fever.
+
+In another mosquito-proof house two soldiers and a surgeon, all
+non-immunes, lived for twenty-one days. From time to time they were
+supplied with soiled articles of bedding, clothing, etc., direct from
+the yellow fever hospital in the city. These articles had been soiled by
+the urine, fecal matter and black vomit obtained from fatal and other
+cases of yellow fever. These articles were handled and shaken daily, but
+no disease developed among the men and at the end of the twenty-one
+days, two other non-immunes relieved them and handled a new supply of
+clothing in the same way, sleeping between the same sheets that had
+been used by a patient dying of yellow fever and exposing themselves in
+every possible way to the soiled clothing. But no disease developed.
+That these men were susceptible was shown later by inoculating some of
+them, when they developed the disease.
+
+In another experiment certain men in a camp allowed themselves to be
+bitten by mosquitoes that had passed through the proper period of
+incubation and every one of them and no others contracted the disease.
+It was also shown that a mosquito was capable of communicating the
+disease as long as fifty-seven days after it had bitten a yellow fever
+patient. Another set of experiments showed that a subcutaneous injection
+into a non-immune of a very small quantity of blood from the veins of a
+yellow fever patient in the first two or three days of the disease would
+produce the fever.
+
+
+SUMMARY OF RESULTS
+
+Since that time much other work has been done by independent workers as
+well as by French and English Commissions both working at Rio de
+Janeiro. The results of their investigation are practically the same and
+may be summed up as follows:
+
+1. The virus of the yellow fever is in the blood-plasma, not in the
+corpuscles, for these may be removed and the plasma still be infective.
+
+2. The virus is conveyed from one patient to another by the yellow fever
+mosquito, _Stegomyia calopus_, and in no other way except by
+experimental injections.
+
+3. The patient is a source of infection only during the first three or
+four days of the disease (this after the three to six days of
+incubation).
+
+4. The virus must undergo an incubation period of twelve to fourteen
+days in the mosquito before she is capable of transmitting the disease.
+
+5. The parasite, whatever it is, has never been seen. It is probably too
+small to be seen by any of our present microscopes, even the recently
+invented ultramicroscope. It is probably not a bacterial parasite but
+very likely a Protozoan, and certain specialists have even shown by the
+study of all the available data that it almost certainly belongs to the
+Sporozoan genus _Spirocheta_.
+
+Now what does all this mean? It means the saving of hundreds of human
+lives annually. It means the banishing from many localities and possibly
+very soon from the face of the earth of a disease that since the
+earliest settlements on this continent has been a source of terror. It
+means the making habitable of certain places which heretofore a white
+man has entered only at the risk of his life. It means that quarantines
+need no longer be established when yellow fever breaks out in a
+district; quarantines which have inevitably caused the loss of millions
+of dollars to the world of commerce.
+
+
+RESULTS IN HAVANA
+
+The first practical work based on these findings was done in Havana. The
+Yellow Fever Commission made their recommendations in 1900. In 1901 and
+1902 they were put into effect. The following table of the death rate
+there during a period of ten years shows graphically the results:
+
+DEATHS IN HAVANA FROM YELLOW FEVER
+
+-----+------+------+------+------+------+------+------+------+------+------
+     | 1893 | 1894 | 1895 | 1896 | 1897 | 1898 | 1899 | 1900 | 1901 | 1902
+-----+------+------+------+------+------+------+------+------+------+------
+Jan. |  15  |   7  |  15  |  10  |  69  |   7  |   1  |   8  |   7  |   0
+Feb. |   6  |   4  |   4  |   7  |  24  |   1  |   0  |   9  |   5  |   0
+Mar. |   4  |   2  |   2  |   3  |  30  |   2  |   1  |   4  |   1  |   0
+Apr. |   8  |   4  |   6  |  14  |  71  |   1  |   2  |   0  |   0  |   0
+May  |  23  |  16  |  10  |  27  |  88  |   4  |   0  |   2  |   0  |   0
+June |  69  |  31  |  16  |  46  | 174  |   3  |   1  |   8  |   0  |   0
+July | 118  |  77  |  88  | 116  | 168  |  16  |   2  |  30  |   1  |   0
+Aug. | 100  |  73  | 120  | 262  | 102  |  16  |  13  |  49  |   2  |   0
+Sep. |  68  |  76  | 135  | 166  |  56  |  34  |  18  |  52  |   2  |   0
+Oct. |  46  |  40  | 102  | 240  |  42  |  26  |  25  |  74  |   0  |   0
+Nov. |  28  |  23  |  35  | 244  |  26  |  13  |  18  |  54  |   0  |   0
+Dec. |  11  |  29  |  20  | 147  |   8  |  13  |  22  |  20  |   0  |   0
+-----+------+------+------+------+------+------+------+------+------+------
+
+As long as the United States held control at Havana the yellow fever
+was kept in check by fighting the mosquitoes, when this vigilance was
+relaxed the fever began to appear again and the Cubans found that it was
+necessary to keep up the fight against the mosquitoes if the island was
+to be kept free from the disease.
+
+
+THE FIGHT IN NEW ORLEANS
+
+In the summer of 1905 came another opportunity to put the knowledge
+gained during these experiments to a practical test. Samuel Hopkins
+Adams in his article in _McClure's Magazine_, June, 1906, says of the
+beginning of this fight:
+
+     "Eight years before, the mosquito-plague had infected the great,
+     busy, joyous metropolis of the south. Ignorant of the real
+     processes of the infection, New Orleans had fought it blindly,
+     frantically, in an agony of panic, and when at last the frost put
+     an end to the helpless city's plight, she lay spent and prostrate.
+     The yellow fever of 1905 came with a more formidable and unexpected
+     suddenness than that of 1897. It sprang into life like a secret and
+     armed uprising in the midst of the city, full-fledged and terrible.
+     But there arose against it the trained fighting line of scientific
+     knowledge. Accepting, with a fine courage of faith that most
+     important preventive discovery since vaccination, the mosquito
+     dogma, the Crescent City marshaled her defenses. This time there
+     was no panic, no mob-rule of terrified thousands, no mad rushing
+     from stunned inertia to wildly impractical action; but instead the
+     enlistment of the whole city in an army of sanitation. Every
+     citizen became a soldier of the public health. And when, long
+     before the plague-killing frost came, the battle was over, New
+     Orleans had triumphed not only in the most brilliant hygienic
+     victory ever achieved in America, but in a principle for which the
+     whole nation owes her a debt of gratitude."
+
+For some time the authorities had been trying to keep secret the fact
+that the disease was prevalent, but the rapidity with which it spread
+made them realize that only united action on the part of all the
+community would be of any avail. The Citizens Volunteer Ward
+Organizations were organized for the purpose of fighting the mosquitoes
+which were everywhere. To many the fight looked hopeless. The miles of
+open gutters, the thousands of cisterns and little pools of standing
+water everywhere furnished abundant breeding-places for the mosquitoes.
+The ditches and ponds were drained or salted, the cisterns were
+screened, infected houses were fumigated, yet the fever continued to
+spread. Rains refilled the ditches, winds tore the screens from the
+cisterns, the ignorant people of the French quarter refused to
+coöperate. At last the city in desperation appealed to the President for
+aid. Surgeon J.H. White and a number of officers and men of the United
+States Public Health and Marine Hospital Service soon took charge of the
+work. This was continued along the same lines as before with the same
+object in view. But with the coming of the regulars the work was more
+systematically and thoroughly done. Every case of fever was treated as
+though it was yellow fever and every precaution taken to prevent
+mosquitoes from biting such a patient. The houses in which the fever
+occurred were thoroughly fumigated to kill any mosquitoes that might be
+there, and the neighborhood was thoroughly searched to find any places
+where the mosquitoes might be breeding. So confident were the
+authorities that the mosquito was the sole cause of the disease
+spreading, that besides fighting it no other work was undertaken save to
+make the sick as comfortable as possible.
+
+Finally the results began to be apparent. The number of cases gradually
+diminished, until long before frost came the city was free from the
+great pest. Yellow fever will doubtless appear from time to time in New
+Orleans and other cities, but there is, at least there should be, small
+danger of another great epidemic, for the people now know how the
+disease is caused and the remedy.
+
+Not long since I had occasion to write to a prominent entomologist in
+Louisiana for some specimens of the yellow fever mosquito for laboratory
+work. The following extract from his reply will show something of the
+work that is still being done there.
+
+     "I am afraid we cannot furnish specimens of _Stegomyia_, in spite
+     of the fact that Louisiana is _supposed_ to be the most favorable
+     home of this species in the South. Since the light occurrence of
+     yellow fever in this State in 1905, a very vigorous war has been
+     kept up against _Stegomyia_, and the ordinances of all Louisiana
+     cities and principal towns require the draining of all breeding
+     places of this mosquito and the constant oiling or screening of all
+     cisterns or other water containers. The result is this species is
+     very rare. Here in Baton Rouge I only see one once in a great
+     while, and it would require perhaps a good many days' work at the
+     present season to get as good specimens and as many of them as you
+     require."
+
+
+IN THE PANAMA CANAL ZONE
+
+Yellow fever was one of the worst obstacles that confronted the French
+when they were attempting to build the Panama Canal. The story of the
+suffering and death from this dread disease there is most pathetic.
+Ship-load after ship-load of laborers were sent over, as those who had
+gone earlier succumbed to the fever. The contractors were responsible
+for their men while they were sick and in order to avoid having to pay
+hospital expenses the men were often discharged as soon as they showed
+signs of sickness. Many of them died along the roadside while
+endeavoring to reach some place where they could obtain aid. The
+hospitals were usually filled with yellow fever patients, a very large
+percentage of whom died.
+
+Not only the day laborers suffered but many of the engineers, doctors,
+nurses and others sickened and died of the disease. It is reported that
+eighteen young French engineers came over on one vessel and in a month
+after their arrival all but one had died of the yellow fever. Out of
+thirty-six nurses brought over at one time, twenty-four died of the
+fever, and during one month nine members of the medical staff of one of
+the hospitals succumbed.
+
+One of the first things that the United States Government did in
+beginning work in the canal zone was to take up the fight against the
+yellow fever mosquito. In Panama where the water for domestic purposes
+was kept in cisterns and water-barrels, inspectors were appointed to see
+that all such receptacles and other possible breeding-places for
+mosquitoes were kept covered. After the first inspection, 4,000
+breeding-places were reported. About six months later there were less
+than 400. Similar work was done in all the towns and settlements along
+the route of the canal. In addition to this fight against the yellow
+fever mosquito considerable attention was paid to the breeding-places of
+the malarial mosquito. The results have been remarkable. Cases of yellow
+fever are now rare throughout this zone, and there has been a very great
+reduction in the extent of the malarial districts. The last case of
+yellow fever occurred in May, 1906. Before this work was done a man took
+his life in his hands when he went into this region. Now it is regarded
+as a perfectly safe place to live. Indeed it is a much safer place than
+many sections of our own country where proper sanitary measures have not
+been taken to protect the health of the community.
+
+
+IN RIO DE JANEIRO
+
+In Rio de Janeiro they have as yet been unable to get rid of the
+mosquitoes, although thousands of dollars are spent annually in fighting
+them. But the non-immunes there protect themselves by doing their
+business in Rio during the day and going back at night to Petropolis,
+twenty-five miles inland and twenty-five hundred feet higher, where
+they are safe, for no _Stegomyia_ have ever been found there.
+
+They claim there that the yellow fever mosquito does not bite during the
+daytime after she has laid her eggs, and that she will not lay her eggs
+until about three days after she has fed on blood, therefore a
+_Stegomyia_ that bites during the day will not carry the yellow fever
+because she is too young. This seems to explain why the fever cannot be
+contracted by being bitten by a mosquito in the daytime. Certain other
+experiments, however, have given different results so that as far as we
+know it is not safe to be bitten at any time by such a mosquito in a
+region where the disease is endemic or where it is epidemic.
+
+In the main the work of the French Yellow Fever Commission working in
+Rio de Janeiro has confirmed the findings of the American Commission.
+One interesting special thing that the French Commission seems to have
+established is that the female may transmit the infecting power to her
+offspring, so that it would be possible for a mosquito that had never
+bitten a yellow fever patient to be capable of infecting a non-immune
+person. While all this is very probable in the light of what we know of
+the disease and the way in which other diseases caused by similar
+organisms may be transmitted by the parent to the offspring, yet the
+most conservative investigators are waiting for further proof.
+
+
+HABITS OF STEGOMYIA
+
+The whole fight against yellow fever, then is directed, as we have seen,
+against the mosquito, _Stegomyia calopus_. The habits of this species
+are such as to make it easy in some respects to combat. It is seldom
+found far away from human habitation. The adults will not fly far. Once
+in a house they usually stay there except when they leave to deposit
+their eggs.
+
+On the other hand, some of these same habits make it all the more
+dangerous. It will breed in almost any kind of water, no matter how
+filthy, and a very small amount will suffice. Thus any leaks from
+water-pipes or drains, cisterns, small cans of water or any such places
+may become dangerous breeding-places. If conditions are unfavorable
+there will often be developed small individuals which can easily make
+their way through ordinary mosquito-netting.
+
+Dr. Manson has pointed out an interesting possible result of the crusade
+that is now being waged against the yellow fever mosquitoes. The
+immunity of the people native to the endemic regions is supposed to be
+due to their having had mild attacks of the fever during childhood, for
+the children in these regions are subject to certain fevers which are
+probably very mild forms of yellow fever.
+
+Now if we kill practically all of the _Stegomyia_ so that these children
+do not have this fever there will be developed, in due time, a
+population most of whom are non-immune.
+
+This freedom from the disease for some time will allow us to grow
+careless in regard to fighting the mosquitoes. They will be allowed to
+increase and by some chance the yellow fever will again be introduced
+and there will then be very grave danger of most extensive and
+destructive epidemics.
+
+
+DANGER OF THE DISEASE IN THE PACIFIC ISLANDS
+
+I have already referred once or twice to the conditions in many of the
+Pacific tropical islands. In some of these various species of
+_Stegomyia_ are abundant, and in some _Stegomyia calopus_ is the most
+abundant and troublesome form. All the natives of these islands are
+non-immune because there has never been any yellow fever there. Unless
+extraordinary care is taken the disease will be introduced there sooner
+or later and the results are sure to be most appalling. The climatic and
+sanitary conditions and the habits of the people are ideal for the
+development and spread of the disease, and what I have seen of the
+conditions on some of these islands convinces me that it would be almost
+impossible to control the disease before it had a chance to kill a large
+percentage of the population.
+
+With the opening of the Panama Canal these things become more possible.
+Heretofore, the shipping to these regions has not been from ports where
+yellow fever was endemic or even likely to be epidemic. But unless the
+yellow fever is kept out of the canal zone, the danger will be many fold
+what it is now.
+
+The white man has already carried enough misery to these island peoples
+in the way of loathsome diseases, and it is to be hoped that this,
+another great curse, will not be carried to them with our civilization,
+the beneficial results of which have been so often very justly
+questioned.
+
+What I have said in regard to these islands applies with equal force and
+in some instances with even greater force to parts of Asia, the Eastern
+Archipelago and other places.
+
+
+
+
+CHAPTER IX
+
+FLEAS AND PLAGUE
+
+
+Plague has always been one of the most dreaded diseases, and when we
+read of its ravages in the old world and the utter helplessness of the
+people before it we do not wonder that the very word filled them with
+horror. One of the greatest scourges ever known began in Egypt about
+A.D. 542, and spread along the shores of the Mediterranean to Europe and
+Asia. It lasted for sixty years, appearing again and again in the same
+place and decimating whole communities.
+
+Another great pandemic, beginning in 1364, spread over the whole of the
+then known world and appeared in its most virulent form. On account of
+diffuse subcutaneous hemorrhages it came to be known as the "black
+death" and of course spread terror in all the communities where it
+appeared. Whole villages and districts were depopulated. The death-rate
+was very high, one authority placing the total mortality at twenty-five
+million.
+
+During this time new centers of infection were established, and since
+then it has been carried by the commerce of the nations to all parts of
+the world. It is not restricted, as many other epidemic diseases, to the
+tropics or semi-tropics, although as a matter of fact we find it is more
+prevalent in these regions on account of the sanitary conditions.
+
+
+HOW PLAGUE WAS CONTROLLED IN SAN FRANCISCO
+
+Attention is called to these things in order that we may compare past
+conditions with present. During the last few years San Francisco has
+been fighting an outbreak of plague that in other days would have been
+nothing less than a national calamity. But with modern methods of
+handling it, based on knowing what it is, what causes it and how it is
+spread, the authorities there have been able not only to hold the
+disease in check, but practically to stamp it out with the loss of
+comparatively few lives.
+
+Dr. Blue of the Public Health and Marine Hospital Service and his
+co-workers directed their whole energy toward controlling the rats. A
+small army of men were employed, catching rats in every quarter of the
+city. Dr. Rucker reports that fully a million rats were slain in this
+campaign. Their breeding-places were destroyed by making cellars,
+woodsheds, warehouses, etc., rat-proof and removing all old rubbish.
+Garbage cans were installed in all parts of the city, as it was required
+that all garbage be stored where rats could not feed upon it, and
+altogether every effort was made to make it as uncomfortable as possible
+for the rats.
+
+The marked success attending this work abundantly confirms the soundness
+of the theory upon which it was based, and serves as another example of
+the way in which science is teaching us how to prevent or control many
+of our most serious diseases.
+
+
+THE INDIAN PLAGUE COMMISSION
+
+In 1896, what proved to be a very serious outbreak of plague, occurred
+in Bombay and spread to other parts of India. In 1898, a commission was
+appointed to inquire into the origin of the different outbreaks, the
+manner in which the disease is communicated, etc. This was known as the
+Indian Plague Commission, and its exhaustive report, together with the
+minutes of the evidence presented to the committee, represents a
+stupendous amount of work on this subject and is the basis for much of
+the later investigation that has been undertaken.
+
+After the consideration of the evidence from various sources the
+commission decided that the principal mode of infection both for man and
+rats was through some sort of an abrasion in the skin, although it
+recognized also the possibility of infection through the nose and
+throat, and possibly, very rarely, through the intestinal tract or other
+places.
+
+Considerable time was spent in considering Dr. Simond's claim, made in
+1898, that fleas which have been parasitic on plague-infected rats
+migrate on the death of their hosts and convey the infection to healthy
+men and rats. Dr. Simond sought to establish the following:
+
+     "Firstly, that plague rats are eminently infective when infected
+     with fleas and that they cease to be infective when they have been
+     deserted by their parasites: Secondly, that living plague bacilli
+     are found in association with fleas which are taken from
+     plague-infected rats: Thirdly, that plague can pass from infected
+     rats to other animals which have not come directly in contact with
+     them or with their infected excretions: Fourthly, that fleas which
+     infest rats will transfer themselves as parasites to men."
+
+After reviewing the experiments which had been made to establish these
+claims the commission believed that sufficient precaution had not been
+taken to prevent infection from other sources and that not enough
+definite evidence was produced. Against this claim much negative
+evidence was considered and the final conclusion was "that suctorial
+insects do not come under consideration in connection with the spread of
+plague."
+
+In 1905 another body of men known as the Advisory Committee was
+appointed to arrange for further studies in India and other places,
+particularly in relation to the mode of dissemination of the disease.
+They at once appointed a new working commission who immediately began
+their studies and experiments. The preliminary reports of their work,
+which are still known as the Reports of the Indian Plague Commission, as
+well as the reports of contributing investigations that are being made
+from time to time, have served to establish entirely Dr. Simond's claims
+and have completely revolutionized the methods of fighting plague.
+
+There are several different types of plague, seeming to depend largely
+on the manner of infection. The most common type is that known as the
+bubonic plague which is characterized by buboes or swellings in various
+parts of the body. This form of infection is usually received through
+the skin in some manner or other. Only rarely does direct man-to-man
+infection occur though there is always the possibility of it. The
+investigations have shown that the flea is the most common agent in
+transferring the disease from rat to rat or from rat to man. This may be
+accomplished by the flea transferring the bacilli directly from one host
+to another on its proboscis, or they may be carried in the alimentary
+canal of the flea and gain an entrance into the skin through an abrasion
+of some kind when the flea is crushed as it is biting, or when some of
+the bacilli are left on the skin in the excreta of the insect.
+
+
+RESULTS OF VERJBITSKI'S EXPERIMENTS
+
+A very important series of experiments bearing directly on this subject
+was made in 1902 and 1903 by Dr. D.T. Verjbitski. The paper giving the
+results of this work was not published in any scientific journal until
+1908 when the Advisory Committee published it in one of their reports.
+The experiments were so well planned and executed and the results so
+definite that I think it is worth while to give in full his summary of
+results. The bugs referred to are bedbugs.
+
+     "(1) All fleas and bugs which have sucked the blood of animals
+     dying from plague contain plague microbes.
+
+     "(2) Fleas and bugs which have sucked the blood of animals which
+     are suffering from plague only contain plague microbes when the
+     bites have been inflicted from 12 to 26 hours before the death of
+     the animals, that is, during that period of their illness when
+     their blood contains plague bacilli.
+
+     "(3) The vitality and virulence of the plague microbes are
+     preserved in these insects.
+
+     "(4) Plague bacilli may be found in fleas from four to six days
+     after they have sucked the blood of an animal dying with plague. In
+     bugs, not previously starved or starved only for a short time (one
+     to seven days), the plague microbes disappear on the third day; in
+     those that have been starved for four to four and one-half months,
+     after eight or nine days.
+
+     "(5) The numbers of plague microbes in the infected fleas and bugs
+     increase during the first few days.
+
+     "(6) The fæces of infected fleas and bugs contain virulent plague
+     microbes as long as they persist in the alimentary canal of these
+     insects.
+
+     "(7) Animals could not be infected by the bites of fleas and bugs
+     which had been infected by animals whose own infection had been
+     occasioned by a culture of small virulence, notwithstanding the
+     fact that the insects may be found to contain abundant plague
+     microbes.
+
+     "(8) Fleas and bugs that have fed upon animals which have been
+     infected by cultures of high virulence convey infection by means of
+     bites, and the more certainly so the more virulent the culture with
+     which the first animal was inoculated.
+
+     "(9) The local inflammatory reaction in animals which have died
+     from plague occasioned by the bites of infected insects is either
+     very slight or absent. In the latter case it is only by the
+     situation of the primary bubo that one can approximately identify
+     the area through which the plague infection entered the organism.
+
+     "(10) Infected fleas communicate the disease to healthy animals for
+     three days after infection. Infected bugs have the power of doing
+     so for five days.
+
+     "(11) It was not found possible for more than two animals to be
+     infected by the bites of the same bugs.
+
+     "(12) The crushing of infected bugs in situ during the process of
+     biting, occasioned in the majority of cases the infection of the
+     healthy animal with plague.
+
+     "(13) The injury to the skin occasioned by the bite of bugs or
+     fleas offers a channel through which the plague microbes can easily
+     enter the body and occasion death from plague.
+
+     "(14) Crushed infected bugs and fleas and their fæces, like other
+     plague material, can infect through the small punctures of the skin
+     caused by the bites of bugs and fleas, but only for a short time
+     after the infliction of these bites.
+
+     "(15) In the case of linen and other fabrics soiled by crushing
+     infected fleas and bugs on them, or by the fæces of these insects
+     the plague microbes can under favorable conditions remain alive and
+     virulent during more than five months.
+
+     "(16) Chemical disinfectants do not in the ordinary course of
+     application kill plague microbes in infected fleas and bugs.
+
+     "(17) The rat flea _Typhlopsylla musculi_ does not bite human
+     beings.
+
+     "(18) Human fleas do bite rats.
+
+     "(19) Fleas found on dogs and cats bite both human beings and rats.
+
+     "(20) Human fleas and fleas found on cats and dogs can live on rats
+     as casual parasites, and therefore can under certain conditions
+     play a part in the transmission of plague from rats to human
+     beings, and vice versa."
+
+
+RESULTS OF VARIOUS INVESTIGATIONS
+
+Various other plague commissions from other countries as well as many
+individuals have investigated the same subject, and the results all
+point conclusively to the fact that the rats and the fleas are at least
+the most important factors in the spread of the disease. The evidence
+from many sources and from many experiments may be briefly summed up as
+follows: The disease is caused by the presence in the system of minute
+bacteria, _Bacillus pestis_. It is probable that plague is primarily a
+disease of rats and only secondarily and accidentally, as it were, a
+disease of man.
+
+Rats are subject to the plague and are often killed by it in great
+numbers. An outbreak of plague among men is often preceded by a very
+noticeable outbreak among rats.
+
+Rats dying of the plague have their blood filled with the plague
+bacillus. Fleas or other suctorial insects feeding on such rats take
+myriads of these bacilli into their stomach and get many on their
+proboscis.
+
+The fleas usually leave a rat as soon as it dies and of course seek some
+other source of food. When such infected fleas are permitted to bite
+other rats or guinea-pigs these animals often develop the disease.
+Several of the species of fleas that infest rats will bite man also, and
+in the cases of many plague patients it can be definitely shown that
+they had recently been bitten by fleas.
+
+
+STRUCTURE AND HABITS OF FLEAS
+
+A study of the structure and habits of fleas shows that in many respects
+they are particularly adapted for spreading such a disease as bubonic
+plague. The piercing proboscis consists of three long needle-like
+organs, the epipharynx and mandibles, and a lower lip or labium. The
+mandibles have the sides serrate like a two-edged saw. The labium is
+divided close to its base so that it really consists of two slender
+four-segmented organs which lie close together and form a groove in
+which the piercing organs lie. When the flea is feeding, the epipharynx
+and mandibles are thrust into the skin of the victim, the labium serving
+as a guide. As the sharp cutting organs are thrust deeper and deeper the
+labium doubles back like a bow and does not enter the skin. Saliva is
+then poured into the wound through minute grooves in the mandibles, and
+the blood is sucked up into the mouth by the sucking organ which lies in
+the head at the base of the mouth-parts. Just above this piercing
+proboscis is a pair of flat, obtuse, somewhat triangular pieces, the
+maxillary blades or maxillæ. When the proboscis is fully inserted into
+the skin the tips of these maxillæ may also be embedded in the tissue
+and perhaps help to make the wound larger. Attached to these maxillæ is
+a pair of rather stout, four-jointed appendages, the palpi. They
+probably act as feelers.
+
+If the flea chances to be feeding on a plague-infected rat or person
+many of the plague bacilli will get on the mouth-parts and myriads of
+them are of course sucked up into the stomach with the blood. Those on
+the proboscis may be transferred directly to the next victim that it is
+thrust into, and those in the stomach may be carried for some time and
+finally liberated when the flea is feeding again or when it is crushed
+by the annoyed host. The latter is probably the most common method of
+infection, for the bacilli that are liberated when the flea is crushed
+may readily be rubbed into the wound made by the flea bite or into
+abrasions of the skin due to the scratching. Kill the flea, but don't
+"rub it in."
+
+[Illustration: FIG. 105--Rat-flea (_Læmopsylla cheopis_); male.]
+
+[Illustration: FIG. 106--Rat-flea (_L. cheopis_); female.]
+
+[Illustration: FIG. 107--Head of rat-flea showing mouth-parts.]
+
+[Illustration: FIG. 108--Human-flea (_Pulex irritans_); male.]
+
+During the recent outbreak in San Francisco many thousand fleas that
+were infesting man, rats, mice, cats, and dogs, squirrels and other
+animals have been studied and it has been found that while each flea
+species has its particular host upon which it is principally found, few
+if any of them will hesitate to leave this host when it is dead and
+attack man or any other animal that may be convenient.
+
+
+COMMON SPECIES OF FLEAS
+
+Throughout India and in all the warm climates where plague frequently
+occurs the most common flea found on rats has come to be known as the
+plague flea (_Læmopsylla cheopus_) (Figs. 105, 106), and is doubtless
+the principal species that is concerned in carrying the disease in those
+climates. It now occurs quite commonly on the rats in the San Francisco
+Bay region and is occasionally found there on man also. In the United
+States, Great Britain and other temperate regions another larger
+species, _Ceratophyllus fasciatus_ is by far the most common flea found
+on rats, and is commonly known as the rat flea. It occurs on both the
+brown and the black rats _Mus norvegicus_ and _M. rattus_, on the house
+mouse and frequently on man. It has also been taken in California on
+pocket gophers and on a skunk.
+
+The common human flea (_Pulex irritans_) (Figs. 108, 109), is found in
+all parts of the inhabited world. Although we regard it primarily as a
+pest of human beings it often occurs very abundantly on cats, dogs, mice
+and rats as well as on some wild mammals such as badgers, foxes and
+others and has occasionally been found on birds.
+
+Most entomologists regard the fleas commonly found on cats and dogs as
+belonging to one species _Ctenocephalus canis_. Others believe them to
+be distinct species and call the cat flea _Ctenocephalus felis_. So far
+as our personal comfort and safety is concerned it makes but little
+difference to us whether the flea that bites us is called _canis_ or
+_felis_ for they both look very much alike, and act alike and the bite
+of one hurts just as much as the bite of the other. Although cats and
+dogs are their normal hosts they are very often troublesome household
+pests, sometimes making a house almost uninhabitable. They are
+frequently found on rats, and therefore may carry the plague bacillus
+from rat to rat or from rat to man.
+
+
+GROUND-SQUIRRELS AND PLAGUE
+
+As early as 1903 Dr. Blue, in charge of the plague suppressive measures
+in San Francisco, became impressed with the possibility of the common
+California ground-squirrels (_Otospermophilus beecheyi_), acting as an
+agent in the transmission of plague. It was rumored at that time that
+some epidemic disease was killing the squirrels in some of the counties
+surrounding San Francisco Bay, notably in Contra Costa County. None of
+the squirrels were examined at that time, but since then many thousand
+have been carefully studied and it has been definitely shown that many
+of them are plague-infected. Just how the plague got started among them
+will probably never be really known. There is little doubt, however, but
+that it was transferred in some way from the rats to the squirrels. The
+trains and the bay and river steamers running out from San Francisco
+would afford abundant opportunity for the rats to go from the city to
+the warehouses all along the shore. Once there they would use the same
+runways as the squirrels about the warehouses and in the near-by fields.
+In harvest time the rats migrate to the fields and make constant use of
+the squirrel holes. The farmers in some sections report that they
+frequently catch more rats than squirrels in traps set in squirrel holes
+at that season of the year.
+
+This close association of the rats and the squirrels affords a good
+opportunity for the fleas infesting them to pass from one host to the
+other.
+
+So far only two species of fleas have been recorded from the
+ground-squirrels. One, _Ceratophyllus acutus_, is very common, sometimes
+literally swarming over the squirrels, particularly if a squirrel is
+sick or weak from any cause. The other species, _Hoplopsyllus anomalus_,
+is less abundant but still quite common. Both of these species infest
+rats also, so the chain of evidence is practically complete. We have
+only to assume that at sometime one or more of the plague-infected rats
+found their way into the region where the squirrels were, and the fleas
+passing from the rats to the squirrels would carry the plague with them.
+
+The fact that the plague already has such a start among the squirrels
+opens a new and very serious phase of the problem of suppressing the
+disease. All who have hunted the ground-squirrels will testify to the
+readiness with which the fleas from them will bite those who are
+handling them. As it is the sick or weak squirrels that are most often
+taken there is always a chance that plague may be transferred from them
+to human beings. The records of the plague cases in California show at
+least three cases in which there seems to be very little doubt that the
+disease resulted from handling plague-infected squirrels.
+
+[Illustration: FIG. 109--Human-flea (_P. irritans_); female.]
+
+[Illustration: FIG. 110--Mouse-flea (_Ctenopsyllus musculi_); female.]
+
+A still more serious thing is the possibility of the disease remaining
+in a more or less virulent form among the squirrels for some time,
+possibly for years, and then breaking out again in some locality where
+the rats or men may become infected. As long as there is a trace of the
+disease among the squirrels there is always the chance of it spreading,
+so that new areas may become infested. Those in charge of the
+plague-suppressive measures are fully aware of these dangers and are
+making a careful study of the situation and will doubtless be able to
+cope with it successfully. It may be that the squirrels will have to be
+exterminated in the infected regions. This would be a long and difficult
+task, but the success attending the fight against the rats in a great
+city shows what can be done when the determination to do it is there.
+
+
+REMEDIES FOR FLEAS
+
+We have seen how a great city set to work to rid itself of the
+plague-sick rats. As a matter of fact it was not the rats that they
+were after primarily. If the rats had not harbored fleas the city would
+have been glad to let the disease take its course and destroy as many
+rats as possible. But it was found that the only way to get rid of the
+fleas that might possibly be infected with the plague was to kill their
+rat hosts.
+
+General cleaning-up measures will of course very materially lessen the
+number of fleas about the private dwellings, but there often remains a
+number of fleas in the house that are a source of great annoyance even
+if the danger is eliminated.
+
+Particularly is this apt to be so in places where cats or dogs are
+members of the household. These animals almost always harbor at least a
+few fleas, and where there are a few there is always a possibility, even
+a great probability, that there will be many more unless an effort is
+made to get rid of them.
+
+In some sections of the country it is the cat and dog flea that is the
+most troublesome to man. The minute white eggs of the fleas are usually
+laid about the sleeping-places of these animals and the slender active
+larvæ that hatch from them feed upon any kind of organic matter that
+they can find in the dust or in the cracks and crevices. About eight or
+ten days after hatching the larvæ spin delicate brownish cocoons in
+which they pass the pupal stage, issuing a few days later as the adult
+fleas.
+
+It will at once appear, then, that it is important to provide the cats
+and dogs with sleeping-places that can be kept clean. If they have a mat
+or blanket to sleep on this can be taken up and shaken frequently and
+the dust swept up and burned. In this way many of the eggs or larvæ may
+be destroyed. Very often the dust under a carpet that has not been taken
+up and dusted for some time will be found to be harboring a multitude of
+fleas or their larvæ. In such cases a thorough cleaning of the carpet
+and the floors will bring relief. Houses that are unused for some time
+during the summer months are often found to be overrun with fleas in the
+fall, for the fleas have had an unmolested opportunity to breed and
+multiply. Such rooms of course require a thorough cleaning or it is
+sometimes possible to kill the fleas by a liberal use of pyrethrum
+powder or benzine or to fumigate. In this connection, Dr. Skinner's note
+in the _Journal of Economic Entomology_ is worth repeating.
+
+     "In the latter part of last May (1908) I moved into a house that
+     had not been previously occupied. No carpet was used and being
+     summer only a few rugs were placed on the floors. A part of the
+     household consisted of a collie dog and three Persian cats. Very
+     soon the fleas appeared, the dog and cat flea, _Ctenocephalus
+     canis_. I did not count them and I can't say whether they numbered
+     a million or only a hundred thousand. On arising in the morning and
+     stepping on the floor one would find from three to a dozen on the
+     ankles. The usual remedies for fleas are either drastic or somewhat
+     unsatisfactory. The drastic one is to send the animals to the
+     institutions, where they are asphyxiated, or take the other advice,
+     'Don't keep animals.'
+
+     "I tried mopping the floors with rather a strong solution of
+     creolin but it did little good. Previous experience with pyrethrum
+     was not very satisfactory. Knowing the volatility of naphthalene in
+     warm weather and the irritating character of its vapor led me to
+     try it. I took one room at a time, scattered on the floor five
+     pounds of flake naphthalene and closed it for twenty-four hours. On
+     entering such a room the naphthalene vapor will instantly bring
+     tears to the eyes and cause coughing and irritation of the air
+     passages. I mention this to show how it acts on the fleas. It
+     proved to be a perfect and effectual remedy and very inexpensive,
+     as the naphthalene could be swept up and transferred to other
+     rooms. So far as I am concerned the flea question is solved and if
+     I have further trouble I know the remedy. I intend to keep the dog
+     and the cats."
+
+
+
+
+CHAPTER X
+
+OTHER DISEASES, MOSTLY TROPICAL, KNOWN OR THOUGHT TO BE TRANSMITTED BY
+INSECTS
+
+
+SLEEPING SICKNESS
+
+One of the worst scourges of Africa and one that is to-day attracting
+world-wide attention is the disease known as trypanosomiasis, the
+terminal phase of which is sleeping sickness, one of the most ghastly
+diseases that we know.
+
+Among the Protozoa referred to in one of the earlier chapters mention
+was made of certain trypanosomes which inhabit the blood of man and
+certain animals. Very little was known concerning these parasites
+previous to the beginning of the present century, but since that time
+several have been found to be of great economic importance. The group is
+being studied extensively and every day our knowledge of them is
+increasing so that we now know quite definitely the life-history of
+several.
+
+_Trypanosoma lewisi_, a parasite of rats, is perhaps the best known as
+it is always common where-ever rats are found. Sometimes as many as 30%
+or 40% of the rats of certain districts are infected. It is thought that
+these are transmitted from rat to rat by the common rat-louse which
+serves as an intermediate host. Fleas may also act as disseminating
+agents.
+
+A few other kinds cause serious disease of animals, but we are more
+interested just now in the particular one that is causing so much
+trouble in Africa. This parasite was discovered in 1902 and was named
+_Trypanosoma gambiensi_ (Fig. 111). Since then it has been found to be
+widely distributed. Although the natives have doubtless long been
+subject to the disease caused by this parasite, the recent influx of
+whites to these regions and the consequent movements of the natives have
+caused a great spread of the disease so that whole regions are now made
+desolate, the inhabitants dying or fleeing to escape the uncanny death.
+
+The disease may run its course in a few months or it may take years. The
+symptoms are various, but infection is usually soon followed by fevers,
+sometimes mild, sometimes severe, which recur at irregular intervals.
+Certain glands or other parts of the body may become swollen. More or
+less extensive skin eruptions occur on all parts of the body and the
+patient gradually becomes anemic and physically and intellectually
+feeble. The nervous system seems to be affected by the parasite, either
+directly or by the action of the toxins it produces. The patient becomes
+more debilitated and morose with an increasing tendency to sleep, hence
+the name sleeping sickness. As the stupor deepens the patient looses all
+desire or power of exertion and as little food is taken he rapidly
+wastes away and finally succumbs for after this final stage is reached
+there is no relief.
+
+It is definitely known that a species of tsetse-fly, _Glossina palpalis_
+(Fig. 112), which somewhat resembles our stable-fly, is responsible for
+the dissemination of the disease, and some recent investigators have
+suggested that certain species of mosquitoes may also carry the parasite
+from one host to another. There still remains some doubt as to the exact
+manner in which the fly transmits the disease, but it seems altogether
+likely that it is an alternative host and does not serve as a simple
+mechanical carrier. In this respect it is like the mosquito which is one
+of the necessary hosts of the malaria parasites, and unlike the
+house-fly which carries the germs of various diseases in a purely
+mechanical way without serving as a definite necessary host for the
+parasite.
+
+The tsetse-fly is found only in tropical Africa and is limited in its
+distribution there to certain very definite, narrow, brushy areas along
+the water's edge. If these places can be avoided there seems to be
+little danger. Those who are fighting the disease have found that if the
+brush in the vicinity of watering-places and ferry-landings is cleared
+away such places become comparatively safe. These flies do not lay eggs
+but produce full-grown larvæ which soon pupate in the ground.
+
+
+ELEPHANTIASIS
+
+In many tropical regions human blood as well as that of other animals is
+the normal habitat of certain worm-like parasites (Nematodes). They are
+not entirely confined to the tropics but may extend far up into the
+subtropical regions. Five or six different species of these parasites
+are known, only one of which, however, has been shown to be of any
+pathological importance, as far as human beings are concerned.
+
+[Illustration: FIG. 111--_Trypanosoma gambiense_; various forms from
+blood and cerebrospinal fluid. (After Manson.)]
+
+[Illustration: FIG. 112--Tsetse-fly. (After Manson.)]
+
+This species, _Filaria bancrofti_, is not only very widely distributed,
+but in regions such as some of the South Sea Islands a very large per
+cent of the natives have the filariæ present in their blood. When these
+parasites are withdrawn from the circulation and placed on a slide for
+study they are seen to be minute transparent, colorless, snake-like
+organisms inclosed in a very delicate sack or sheath. They are but a
+little more than one-hundredth of an inch long and about as big around
+as a red blood-corpuscle. These are the larval forms of the parasite and
+have been called by Le Dantec the micro-filaria.
+
+If blood of the patient drawn from the skin, is examined during the day
+few if any of these parasites are found, but if it is examined between
+five or six o'clock in the evening and eight or nine o'clock the next
+morning they may be found in numbers. During the daytime they have
+retired from the peripheral circulation to the larger arteries and to
+the lungs, where they may be found in great numbers.
+
+This night-swarming to the peripheral circulation has been found to be a
+remarkable adaptation in the life-history of the parasite, for it has
+been demonstrated that in order to go on with its development these
+larval forms must be taken into the alimentary canal of the mosquito.
+Most of the mosquitoes in which the development takes place are
+night-feeders, so that the parasites are sucked up with the blood of the
+victim. Once inside the stomach they soon free themselves from the
+inclosing sheath and make their way through the walls of the stomach and
+enter the muscular tissue, particularly the thoracic muscles. Here they
+undergo a metamorphosis and increase enormously in size, some attaining
+one-sixteenth of an inch in length.
+
+After sixteen to twenty days they leave these muscles and make their way
+to other parts of the body. A few may be found in different parts of the
+abdomen, but most of them make their way forward into the head of the
+mosquito and coil themselves up close to the base of the proboscis,
+finally finding their way down into the proboscis inside the labium.
+Here they lie until an opportunity offers for them to escape to the warm
+blood of a vertebrate. They probably pass through the thin membrane
+connecting the labella with the proboscis and there find their way into
+the wound made by the puncture when the insect bites. Whether these
+parasites can gain an entrance into the circulatory system in any other
+way is not known. It has been suggested that the mosquitoes dying and
+disintegrating on the surface of water may liberate the filariæ which
+may later find their way into the system of the vertebrate host when the
+water is used for drinking, but most of the investigations made so far
+seem to indicate that they make their way directly from the proboscis
+into the new host.
+
+Soon after entering the circulatory system of the human host the
+parasites make their way into the lymphatics where they attain sexual
+maturity, and in due time new generations of the larval filariæ or
+microfilariæ are poured into the lymph, and finally into the definite
+blood-vessels, ready to be sucked up by the next mosquito that feeds on
+the patient.
+
+In most cases of infection the presence of these filariæ in the blood
+seems to cause no inconvenience to the host. They are probably never
+injurious in the larval stage, that is, in the stage in which they are
+found in the peripheral circulation.
+
+In many cases, however, the presence of the sexual forms in the
+lymphatics may cause serious complications. The most common of these is
+that hideous and loathsome disease known as elephantiasis in which
+certain parts of the patient becomes greatly swollen and distorted. An
+arm or a leg may become swollen to several times its natural size, or
+other parts of the body may be seriously affected.
+
+In some of the South Sea Islands 30% to 40% of the natives are afflicted
+in this way, some only slightly others seriously. There is little or no
+pain, but in severe cases the distorted parts often render the patient
+entirely helpless.
+
+The exact way in which the parasites cause such swelling is not very
+definitely known. Manson, who has done more work on these diseases than
+any one else, believes that the trouble arises from the clogging of the
+lymphatic glands or trunks, thus cutting them off from the general
+circulation, in which case the affected parts may become distorted. This
+clogging of the passages is believed to be due to the presence of great
+numbers of immature eggs which have been liberated by parasites injured
+in some way before their eggs were entirely developed.
+
+This interference with the lymphatic circulation brings about the
+anomalous condition of a patient with a serious filarial disease with
+fewer of the filarial parasites in his blood than one who is not so
+seriously affected. This is supposed to be due to the fact that the
+disease-producing parasites have died and that the lymphatics have
+become so obstructed that any microfilariæ they may contain cannot make
+their way into the general circulation. Such a patient then would not be
+as likely to infect a mosquito as would one less seriously affected.
+
+It has always been thought that little or nothing could be done in the
+way of successfully treating this disease, but quite recently a French
+physician, who has been conducting a long series of experiments in the
+Society Islands, announced that he is able to cure many cases by certain
+surgical operations on the affected parts.
+
+
+DENGUE OR "BREAKBONE FEVER"
+
+This is another disease of the tropics often occurring in widespread
+epidemics. It is probably most frequently met with in the West Indies,
+but may occur in any of the tropical countries or islands. Occasionally
+it spreads into subtropical or even temperate regions. Several extensive
+epidemics have occurred in the United States. Once introduced into a
+community it spreads very rapidly and nothing seems to confer immunity.
+
+The various names by which it has been called well describe its effect
+on the patient; breakbone fever, dandy-fever, stiff-necked or
+giraffe-fever, boquet (or "bucket") fever, _scarlatina rheumatica_,
+polka-fever, etc. While the suffering is intense as long as the disease
+lasts it seldom terminates fatally.
+
+It has always been classed as a very contagious disease and it has not
+yet been definitely shown that it is not. Recent observations, however,
+have shown that it is probably caused by a certain Protozoan parasite
+that is found in the blood of dengue patients and several experiments
+have been conducted by Dr. Graham which seem to indicate that it is
+transmitted by mosquitoes. In these experiments, _Culex fatigans_, a
+common tropical or subtropical mosquito, was used. The same parasite
+that is found in the human blood may be found in the stomach and blood
+of the mosquitoes up to the fifth day after it has fed on a dengue
+patient.
+
+Sick and healthy individuals were allowed to remain in close contact in
+a room from which the mosquitoes had been excluded, and the disease was
+not spread. Mosquitoes that had bitten dengue patients were taken to a
+higher region where dengue had never occurred and allowed to bite two
+healthy persons. Both developed the disease and as they were protected
+from other mosquitoes until they had recovered, the disease did not
+spread to others of the community. These and other observations seem to
+make a complete chain of evidence, and most medical men to-day accept
+the theory as well proved and in their practice take every precaution to
+prevent the spread of the disease by keeping the infected patient from
+being bitten by the mosquitoes.
+
+The yellow fever mosquito is also suspected of carrying this same
+disease, and it is possible that other species are also concerned. If
+it is true that the parasite can be carried by several different species
+of mosquitoes this would account very largely for its rapid spread
+wherever it is introduced into a community. Where it occurs outside the
+tropics it is only in the warm summer months when mosquitoes are always
+abundant.
+
+
+MALTA OR MEDITERRANEAN FEVER
+
+This is also a tropical and subtropical disease that occasionally gets
+up into the temperate region, sometimes occurring in the United States.
+The fever begins with a severe headache, and other symptoms follow. It
+is usually of the remittent type and may continue for some months.
+
+It is caused by minute bacteria (_Micrococcus melitensis_) and is a very
+infectious but not usually contagious disease. The germ is readily
+conveyed by inoculation, and several investigators have sought to show
+that the mosquito often serves as the inoculating agent. The disease is
+especially prevalent during the mosquito season, and has twice been
+conveyed to monkeys by infected insects.
+
+
+LEPROSY
+
+This loathsome disease has long been known to be caused by a particular
+bacillus (_Bacillus lepræ_), but the way in which this organism gains
+an entrance into the system is still unknown. Many theories have been
+propounded, but none of them has been well established. Within recent
+years the possibility of insects carrying the germ and in one way or
+another transmitting it to healthy individuals has been suggested and
+much discussed. As the lepræ bacilli are present in the skin and ulcers
+of leprous patients, insects sucking the blood or feeding on the sores
+could not help taking some of them into their body or becoming
+contaminated. These bacilli have been found at various times in the
+stomach or intestine of mosquitoes, fleas and bedbugs. So it is believed
+by some that these and other insects, such as lice and flies, may
+sometimes transmit the disease. On a previous page we have referred to
+the possibility of the face-mites acting as disseminators of leprosy.
+
+Leprosy occurs most commonly among people where little attention is paid
+to bodily cleanliness. Such people are usually freely infested with
+various parasites that thrive well in the filth, so if the germs can be
+transmitted in this way the carriers are there in abundance.
+
+The fact that the sores usually occur on exposed parts of the body has
+been pointed to as evidence that inoculation is due to such insects as
+flies and mosquitoes. It has been noted that leprosy is frequently very
+common in regions where elephantiasis occurs, suggesting the possibility
+of the same carrier, the mosquito, for both diseases. So while there is
+as yet very little evidence one way or the other, insects that are found
+around leprous patients are to be regarded with suspicion, for until we
+know more definitely just how the disease is communicated the insects
+must be looked on as possible sources of contamination.
+
+
+KALA-AZAR OR DUM-DUM FEVER
+
+This is a very fatal infectious disease of many tropical and subtropical
+regions, spreading terror among the natives wherever it occurs. It is
+caused by the presence in the system of Protozoan parasites, the
+so-called Leishman-Donovan bodies, that have recently been studied by
+several observers.
+
+Dr. W.S. Patton of the Indian Medical Service has been making some
+extensive experiments with the common bedbug of India (_Cimex
+rotundatus_) which seem to demonstrate fully that this insect is
+responsible for the transmission of the parasite that causes the
+disease. He has found the parasite in all stages of development in the
+bedbug. This, taken with a number of other observations in regard to the
+tendency of the disease to cling to particular houses, makes a strong
+case against the bedbug. Manson, however, believes that the parasite may
+be transmitted by other agents also, possibly by means of flies that
+visit the sores or in other ways.
+
+
+ORIENTAL SORE
+
+This disease, once supposed to be confined to the Orient, is now found
+to be rather widely distributed throughout the tropics, where it is
+sometimes very prevalent. It is caused by the presence in the system of
+a parasite very similar to or identical with the one causing _kala-azar_
+and is regarded by some as a modified form of that disease. The patient
+is affected with one or more serious sores or ulcers which usually occur
+on exposed parts of the body.
+
+The parasite that causes the disease is supposed to be carried by
+insects either directly or indirectly.
+
+In the latter case the insect may act as an intermediate host.
+
+Dogs and camels are also attacked by this disease and may be sources of
+infection.
+
+
+
+
+BIBLIOGRAPHY
+
+
+A complete list of books and articles dealing more or less directly with
+the subjects discussed in this book would be too extended for use here.
+For the past ten or twelve years many of the medical and biological
+journals have contained articles in almost every issue, discussing these
+subjects in some of their phases. I have selected only a few of the more
+important of them, and these only the English ones, confining myself
+mostly to those that I have personally consulted, and giving brief
+annotations. Many of these will be found to include very full
+bibliographies of the particular subject treated.
+
+In order to avoid repetition, references are given under one head only
+although many might properly be included in other sections as well.
+
+
+PARASITES AND PARASITISM
+
+     BRAUN, MAX. Animal Parasites of Man. Translated by Pauline Falcke
+     and edited by L.W. Sambon and F.V. Theobald. Third edition, 1906. A
+     chapter on the general subject of parasitism and a description of
+     parasites of all classes. Bibliography.
+
+     LEUCKART, R. The Parasites of Man and the Diseases Induced by Them.
+     Eng. transl., London, 1886.
+
+     NEUMAN, THEO. Entoparasites and Hygiene. _Trans. Vassar Bros.
+     Institute_, VII, 1895. A general discussion of parasitism;
+     life-history of some common parasites that infest man.
+
+     NEUMANN, L.G. Treatise on the Parasites and Parasitic Diseases of
+     the Domesticated Animals. Eng. transl. by Fleming, 1892.
+
+     RANSOM, B.H. How Parasites Are Transmitted. _Year Book U.S. Dept.
+     Agric._, 1905, pp. 139-166 (pub. 1906). Discusses the ways in which
+     parasites of all classes are transmitted.
+
+     SAMBON, L. The Part Played by Metazoan Parasites in Tropical
+     Pathology. _Jour. Trop. Med. & Hyg._, Vol. XI, Jan. 15, 1908. A
+     comprehensive discussion of this subject.
+
+     SHIPLEY, A.E., AND FEARNSIDES, E.G. Effects of Metazoan Parasites
+     on Their Hosts. _Jour. Econom. Biology_, Vol. I, 1906, pp. 41-62.
+     Discusses injury due to mere presence of parasite in host; to the
+     migration of the parasite; loss to host by feeding of parasites;
+     injury by certain toxins.
+
+     STILES, C.W. Diseases Caused by Animal Parasites. _Osler's Mod.
+     Med._, Vol. I, 1907, p. 525. General discussion; Trematodes;
+     Cestodes; Roundworms; Acariasis; Parasitic Insects; Myiasis.
+
+     VAN BENEDEN, P.J. Animal Parasites and Messmates. 1889. Contains
+     much that is interesting.
+
+     WARD, HENRY B. Influence of Parasitism on the Host. _Proc. Amer.
+     Assn. for Advancement of Science_, Vol. 56, 1907. A comprehensive
+     statement of this subject. List of literature.
+
+
+PROTOZOA
+
+     CALKINS, G.N. The Protozoa. _Osler's Mod. Med._, Vol. I, 1907, p.
+     353. General notes on the Protozoa; classification; reproduction;
+     life-cycle of various forms. Regards Protozoa as subkingdom and the
+     four great divisions as phyla.
+
+     CALKINS, G.N. Protozoölogy. N.Y., 1909. Chapters on parasitism,
+     pathogenic Protozoa, etc.
+
+     CLARKE, J.J. Protozoa and Disease. London, 1903, Pt. I. Discusses
+     the various protozoa that cause disease, and refers frequently to
+     those that are transferred from host to host by insects.
+
+     CLARKE, J.J. Protozoa and Disease. London, 1908. Part II,
+     comprising sections on the causation of smallpox, syphilis and
+     cancer. Notes on parasitic Protozoa, tropical diseases, ticks,
+     piroplasmosis, etc.
+
+     DANIELS, C.W. Persistence of the Tropical Diseases of Man Due to
+     Protozoa. _Jour. Trop. Med. & Hyg._, 12, Aug. 2, 1909, pp. 232-234.
+     Same in _Lancet_, II, 1909, p. 460. Good summary of present
+     knowledge of the subject.
+
+     MINCHIN, E.A. Protozoa. In Albutt and Rolleston's _System of
+     Medicine_, II, 1907, pp. 9-122. A comprehensive chapter on
+     Protozoa. Many parasitic forms are figured and described.
+     Bibliography.
+
+     MINCHIN, E.A. The Sporozoa. In Lankester's _Treatise on Zoöl._, Pt.
+     I, pp. 150-360, 1903. Best account of this group, list of Sporozoan
+     hosts. Bibliography.
+
+
+BACTERIA
+
+     FLEXNER, SIMON. Relation of Bacteria and Sporozoa to Disease.
+     _Science_, N.S., Vol. 27, No. 682, pp. 133-136. On these pages
+     discusses relation of bacteria and Protozoa to human diseases.
+
+     JORDAN, EDWIN O. General Bacteriology. Philad., 1898. A good
+     general treatment of the subject.
+
+     LEVY, ERNST, AND KLEMPERER, FELIX. Elements of Clinical
+     Bacteriology for Physicians and Students (transl. by A.A. Eschner),
+     Philad., 1909. Morphology and biology of bacteria; infection;
+     immunity; specific diseases of bacterial origin, etc.
+
+     MUIR, ROBT., AND RITCHIE, JAS. Manual of Bacteriology. N.Y., 1903.
+     Contains chapter on the relation of bacteria to diseases and
+     discussion of several bacterial diseases.
+
+     STERNBERG, G.M. A Manual of Bacteriology. N.Y., 1893. Part III is
+     devoted to pathogenic bacteria.
+
+
+INSECTS AND DISEASE
+
+     HERMS, W.B. Medical Entomology, Its Scope and Methods. _Jour. of
+     Eco. Ento._, Vol. 2, No. 4, 1909, pp. 265-268.
+
+     HOWARD, L.O. Insects as Carriers and Spreaders of Disease. _Year
+     Book U.S. Dept. Agric._, 1901, pp. 177-192. Good review of the
+     subject.
+
+     HOWARD, L.O. How Insects Affect Health in Rural Districts. _U.S.
+     Dept. Agric., Farmers' Bulletin, No. 155_, 1902. Discussion of city
+     and county conditions; protection from typhoid, malaria and yellow
+     fever.
+
+     HOWARD, L.O. Economic Loss to the People of U.S. Through Insects
+     That Cause Disease. _Bull. 78, U.S. Dept. Agric. Bur. of Ent._,
+     1909. A comprehensive discussion and summary of the subject.
+     Discusses mosquitoes, flies, the Panama Canal, epidemic diseases
+     and the progress of nations.
+
+     KELLOGG, V.L. Insects and Disease, Chap. XVIII, in _American
+     Insects_, pp. 615-654, 1905. Discusses Mosquitoes and malaria;
+     yellow fever and filariasis.
+
+     KING, H.H. Report on Economic Entomology of Khartoum, in _Third
+     Rept. of Wellcome Research Lab._, 1908. Discusses insects injurious
+     to man: mosquitoes, blood-sucking insects other than mosquitoes,
+     etc.
+
+     MASON, C.F. The Spread of Diseases by Insects, with Suggestions
+     Regarding Prophylaxis. _International Clinics_, Vol. II, 1904, pp.
+     1-21. A brief summary of the subject.
+
+     MCCRAE, JOHN. Recent Progress in Tropical Medicine. _International
+     Clinics_, Vol. II, 1904, pp. 22-36. Discusses several diseases,
+     some of which are transmitted by insects.
+
+     NUTTALL, G.H.F. On the Rôle of the Insects Arachnids and Myriapods
+     as Carriers in the Spread of Bacterial and Parasitic Diseases of
+     Man and Animals. A critical and historical study. _Johns Hopkins
+     Hospital Reports_, Vol. 8, 1899, pp. 1-154. A review of all the
+     literature up to this date. Important article.
+
+     NUTTALL, G.H.F. Insects as Carriers of Disease. Recent advances in
+     our knowledge of the part played by blood-sucking arthropods
+     (exclusive of mosquitoes and ticks) in the transmission of
+     infectious diseases. Bericht über den XIV. Intern. Kongress für
+     Hygiene und Dermogrophic. Berlin, 1907, pp. 195-206. Discusses
+     protozoan and bacterial diseases.
+
+     STILES, C.W. Insects as Disseminators of Disease. _Virginia Medical
+     Semi-monthly_, Vol. 6, No. 3, May 10, 1901, pp. 53-58. Good
+     statement of subject with list of recent workers.
+
+     WHERRY, W.B. Insects and Infection. _Cal. State Jour. of Med._,
+     Nov., 1907. Discusses the rôle of insects, ticks, etc., in the
+     transmission of infectious diseases.
+
+     Symposium on Yellow Fever and Other Insect-borne Diseases.
+     _Science_, N.S., Vol. 23, Nos. 584-585, 1906. The Protozoan
+     Life-cycle, G.N. Calkins. Filariasis and Trypanosome Diseases, H.B.
+     Ward. The Practical Results of Reed's Findings on Yellow Fever
+     Transmission, J.H. White. Difficulties of Recognition and
+     Prevention of Yellow Fever, Q. Kohnke. The Practical Side of
+     Mosquito Extermination, H.C. Weeks. Without Mosquitoes There Can Be
+     No Yellow Fever, Jas. Carroll. Estivo-autumnal Fever, Cause,
+     Diagnosis, Treatment and Destruction of Mosquitoes Which Spread the
+     Disease, H.A. Veazie.
+
+
+MOSQUITOES--SYSTEMATIC AND GENERAL
+
+     BALFOUR, ANDREW, AND STAFF. _Second Report of the Wellcome Research
+     Laboratories at the Gordon Memorial College_, Khartoum, 1906.
+     Includes reports on work on mosquitoes and other noxious insects.
+
+     BOYCE, SIR ROBERT W. Mosquitoes or Man? The Conquest of the
+     Tropical World. N.Y., 1909. Reviews medical and sanitary work in
+     the tropics and discusses the relation of insects to various
+     tropical diseases.
+
+     BUSCH, AUGUST. Report on a Trip for the Purpose of Studying the
+     Mosquito Fauna of Panama. _Smith. Miscell. Coll._, Vol. 5, Pt. I,
+     1908, p. 49. Work that is being done in Panama to control the
+     mosquitoes. Annotated list of species.
+
+     FELT, E.P. Mosquitoes or Culicidæ of New York State. In _N.Y. State
+     Museum Bull. 79_, Entomology 22, 1904. Discusses distribution,
+     migration and life-history of various species of mosquitoes and
+     mosquito diseases. Bibliography.
+
+     GILES, GEO. M. A Handbook of Gnats or Mosquitoes, Giving the
+     Anatomy and Life-History of the Culicidæ. London, 1902. Whole
+     subject treated very fully.
+
+     GRUBBS, S.B. Vessels as Carriers of Mosquitoes. _Pub. Health and
+     Mar. Hospt. Ser. Bull._ II, Mar. 3, 1903. Believes that mosquitoes
+     may come aboard when the vessel is lying at anchor one-half mile
+     from shore, and that under favorable conditions they may come
+     aboard when the vessel is fifteen miles from shore.
+
+     HOWARD, L.O. Mosquitoes. _Osler's Mod. Med._, Vol. I, p. 370, 1907.
+     General notes on classification and habits particularly in relation
+     to diseases.
+
+     HOWARD, L.O. Notes on Mosquitoes of the United States. _U.S. Dept.
+     Agric., 1900. Div. of Ento. Bull. No. 25_, N.S. Account of the
+     structure; biology; remarks on remedies.
+
+     HOWARD, L.O. Concerning the Geographic Distribution of the Yellow
+     Fever Mosquito. _Public Health Rept., Pub. Health and Mar. Hospt.
+     Ser._, Nov. 13, 1903. The same revised to Sept. 10, 1905.
+
+     HOWARD, L.O. Mosquitoes: How They Live; How They Carry Disease;
+     How They Are Classified; How They May Be Destroyed. N.Y., 1901. One
+     of the best popular books on mosquitoes.
+
+     MCCRACKEN, I. _Anopheles_ in California, with a Description of a
+     New Species. _Entomological News_, Vol. 15, Jan., 1904. Records of
+     three species, their breeding-places, habits, etc.
+
+     MITCHELL, EVELYN G. Mosquito Life. N.Y., 1907. A good popular
+     account of the mosquitoes and their relation to disease. The
+     appendix treats of mosquitoes and their possible relation to
+     leprosy.
+
+     SMITH, J.B. Mosquitoes Occurring Within the State of New Jersey.
+     Report of the New Jersey State Agric. Exper. Station upon the
+     mosquitoes occurring within the State. Trenton, N.J., 1904. Habits,
+     development, relation to disease, checks and remedies; systematic.
+
+     SMITH, J.B. The General Economic Importance of Mosquitoes. _Popular
+     Science Monthly_, 70, 1907, pp. 325-329. Mosquitoes affect not only
+     the health and comfort of the people, but hinder development of
+     agriculture and thus affect land values.
+
+     SMITH, J.B. The New Jersey Salt-marsh and Its Improvement. _New
+     Jersey Agricultural Experiment Station Bulletin_, 207, 1907. Shows
+     that the increased value of the land drained in the antimosquito
+     crusade more than pays for the cost of the drainage.
+
+     THEOBALD, F.V. Monograph of _Culicidæ_ of the World. Four Vols. and
+     one Vol. of plates. London, 1901 to 1907. Vol. I contains 96 pages
+     on structure, life-history, habits, etc. Vol. II contains a
+     bibliography. Vol. Ill contains a list of species that carry
+     disease.
+
+     THEOBALD, F.V. Mosquitoes or _Culicidæ_. In Albutt and Rolleston's
+     _System of Medicine_, II, 1907, pp. 122-168. Structure,
+     life-history, habits, distribution and classification of
+     mosquitoes. Bibliography.
+
+
+MOSQUITO ANATOMY
+
+     BERKELEY, WM. M. Laboratory Work with Mosquitoes. N.Y., 1902.
+     Chapters on development, anatomy, dissection, malarial parasites,
+     filarial disease, yellow fever.
+
+     DIMMOCK, GEO. Anatomy of the Mouth-parts and Suctorial Apparatus of
+     _Culex_. _Psyche_, 3, pp. 231-241, Sept., 1881. Good.
+
+     IMMS, A.D. On the Larval and Pupal Stages of _Anopheles
+     maculipennis_. _Journal Hygiene_, Vol. 7, No. 2, April, 1907.
+     Morphology.
+
+     IMMS, A.D. On the Larval and Pupal Stages of _Anopheles
+     maculipennis_. _Parasitology_, Vol. I, No. 2, June, 1908.
+     Continuation of article in _Jour. Hyg._, Vol. 7, No. 2. Continues
+     discussion of morphology.
+
+     NUTTALL, GEO. F., CORBETT, LOUIS, AND STRANGEWAYS-PIG, T. Studies
+     in Relation to Malaria. Pt. I, The Geographical Distribution of
+     _Anopheles_ in Relation to the Former Distribution of Ague in
+     England. _Jour. Hyg._, Vol. I, No. 1, Jan., 1901.
+
+     NUTTALL, GEO. F., AND SHIPLEY, ARTHUR E. Studies in Relation to
+     Malaria. Pt. II, Structure and Biology of _Anopheles_, _Jour Hyg._,
+     Vol. I, No. 1, Jan., 1901: The Egg and Larva; Bibliography. Pt. II,
+     cont, Vol. I, No. 2, April, 1901: The Pupa. Pt. II, cont., Vol. I,
+     No. 4, Oct., 1901: Adult External Anatomy. Pt. II, cont., Vol. 2,
+     No. 1, Jan., 1902: Ætiology of Adult. Pt. II, cont., Vol. Ill, No.
+     2, April, 1903: Anatomy of Adult.
+
+     THOMPSON, MILLETT T. Alimentary Canal of the Mosquito. _Proc. Bost.
+     Soc. Nat. Hist._, Vol. 32, No. 6, 1905, pp. 145-202. Good summary
+     of recent investigations.
+
+     WESCHE, W. The Mouth-parts of _Nemocera_ and Their Relation to the
+     Other Families of _Diptera_. _Royal Microscopic Soc. Jour._, 1904,
+     pp. 28-47. Discussion with illustrations of the mouth-parts of
+     various _Diptera_.
+
+
+MOSQUITOES--LIFE-HISTORY AND HABITS
+
+     AYERS, E.A. The Secrets of the Mosquito. A guide to the
+     extermination of the prolific pest. _World's Work_, 1907, Vol. 14,
+     pp. 8902-8910. Notes on life-history and methods of control.
+
+     JORDAN, E.O., AND HEFFERAN, MARY. Observations on the Bionomics of
+     _Anopheles_. _Jour. Infec. Diseases_, II, 1905, pp. 56-69.
+     Occurrence, breeding-places, habits, etc.
+
+     MORGAN, H.A., AND DUPREE, J.W. Development and Hibernation of
+     Mosquitoes. _Bull. 40_, N.S., _Div. of Ento._, pp. 88-92, 1903.
+     Results of observation on five genera of mosquitoes in the vicinity
+     of Baton Rouge, La.
+
+     ROSS, E.H. The Influence of Certain Biological Factors on the
+     Question of the Migration of Mosquitoes. _Jour. Trop. Med. & Hyg._,
+     12, 1909, pp. 256-258, Sept. 1. Only fecundated females feed on
+     blood, and must be fertilized after each batch of eggs. This
+     determines largely the time and place of breeding.
+
+     SMITH, J.B. Concerning Migration of Mosquitoes. _Science_, 18, Dec.
+     11, 1903, pp. 761-764. Observations on the migrations of
+     mosquitoes, particularly _C. sollicitans_.
+
+
+MOSQUITO FIGHTING
+
+     CELLI, ANGELO. The Campaign Against Malaria in Italy. Transl. by
+     J.J. Eyre. _Jour. Trop. Med. & Hyg._, XI, Apr. 1, 1908, pp.
+     101-108. Includes a good discussion of the effectiveness of
+     destroying the mosquitoes in controlling malaria.
+
+     FELT, E.P. Mosquito Control. In _Report of the N.Y. State
+     Entomologist for 1905_, pp. 109-116. Notes on importance and
+     methods of control of various species.
+
+     GOLDBERGER, JOS. Prevention and Destruction of Mosquitoes. _Public
+     Health Reports, Pub. Health and Mar. Hospt. Ser._, July 17, 1908.
+     Life-histories and methods of fighting larvæ, pupæ and adults.
+
+     LE PRINCE, J.A. Mosquito Destruction in the Tropics. _Jour. Amer.
+     Med. Assn._, LI, p. 26, Dec. 26, 1908. Occurrence and habits of
+     _Anopheles_, methods of destruction. Results of anti-malarial work
+     on the isthmus. Discussion by various doctors.
+
+     QUAYLE, H.J. Mosquito Control Work in California. _Bull. No. 178,
+     Calif. Agric. Ex. Sta._, pp. 1-55, 1906. Habits and life-history of
+     California species, with an account of experiments to control the
+     salt-marsh species.
+
+     ROSENAN, M.J. Disinfection Against Mosquitoes with Formaldehyde and
+     Sulphur Dioxid. _Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull.
+     6_, 1901.
+
+     ROSS, RONALD. Mosquito Brigades and How to Organize Them. New York,
+     1902.
+
+     ROSS, RONALD. Logical Basis of the Sanitary Policy of Mosquito
+     Reduction. _Science_, N.S., Vol. 22, No. 750, Dec. 1, 1905, pp.
+     689-699. Important article dealing with the methods of control.
+
+     SMITH, J.B. Salt-marsh Mosquitoes. _New Jersey Agric. Exper. Stn.
+     Special Bulletin T_, 1902. Breeding-places and methods of control
+     of this species.
+
+     SMITH, J.B. Mosquitocides. _Bull. 40, New Series U.S. Dept. Agric.,
+     Div. of Ento._, pp. 96-108, 1903. Results of experiments with a
+     number of substances, several of which were found to be effective
+     and some cheap enough to permit of their use to a limited extent.
+
+     SMITH, J.B. The New Jersey Salt-marsh and Its Improvement. _Bull.
+     No. 207_, Nov. 14, 1907, _New Jersey Agric. Exper. Stn._ Results of
+     draining the marshes to get rid of mosquitoes.
+
+     SMITH, J.B. The House Mosquito: a City, Town and Village Problem.
+     _N.J. Agric. Ex. Stn. Bull. 216_, 1908. Work done on salt-marshes
+     since 1904 practically eliminated the migratory species, so that
+     _C. pipens_, the house mosquito, is now the problem. Life-history
+     and methods of combating.
+
+     UNDERWOOD, W.L. Mosquitoes and Suggestions for Their Extermination.
+     _Pop. Sci. Mo._, Vol. 63, 1903, pp. 453-466. Life-history, habits
+     and methods of control.
+
+     UNDERWOOD, W.L. The Mosquito Nuisance and How to Deal with It.
+     Boston, 1903.
+
+     First Antimosquito Convention, 1903. Pub., Brooklyn, 1904. Contains
+     articles on what railroads, government and laws should do toward
+     mosquito extermination; mosquito work in Havana; how state
+     appropriations should be used, etc.
+
+     National Mosquito Extermination Society. Bulletin No. 1, 1904.
+     Object of Society; brief sketches of Ross, Reed, and others.
+     Reprints of a few articles on mosquito extermination.
+
+     American Mosquito Extermination Society. _Year Book for 1904-05._
+     N.Y., 1906. Containing reports of meetings and discussions of
+     various problems. Several interesting papers, among them "Criminal
+     Indictment of the Mosquito," F.W. Moss. "Mosquito Work at Panama
+     Canal," W.C. Sorgas. "Diversities Among New York Mosquitoes," E.P.
+     Felt. "Mosquito Extermination in New Jersey," J.B. Smith. "The
+     Mosquito Question," Quitman Kohnke.
+
+     Antimalarial Work in the Panama Canal Zone. Editorial in _Jour.
+     Trop. Med. & Hyg._, XI, Aug. 15, 1908, p. 251. Notes on the success
+     of the measures adopted there.
+
+
+MOSQUITOES AND DISEASE
+
+     DOTY, A.H. The Mosquito, Its Relation to Disease and Its
+     Extermination. _New York State Journal of Medicine_, May, 1908.
+
+     FINLAY, CHAS. Mosquitoes Considered as Transmitters of Yellow Fever
+     and Malaria. _Med. Record_, May 27, 1899, pp. 737-739. Review of
+     his theory in regard to mosquitoes and disease and the probable
+     necessary changes in view of recent discoveries.
+
+     HOWARD, L.O. Mosquitoes as Transmitters of Disease. _Review of
+     Reviews_, XXIV, 1901, pp. 192-195. A review of the work of various
+     investigators.
+
+     SMITH, J.B. Sanitary Aspect of the Mosquito Question. _Medical
+     News_, Mar. 7, 1903. Note on mosquitoes and their relation to
+     disease.
+
+     TAYLOR, J.B. Observations on the Mosquitoes of Havana, Cuba.
+     Reprint from _La Revista de Medicina_, June, 1903, p. 27.
+
+
+MALARIA
+
+     BANKS, C.S. Experiments in Malarial Transmission by Means of
+     _Myzomyia ludlowii_. _Phil. Jour. Sci._, B. 2, 1907, pp. 513-535.
+     Breeding-places of mosquitoes, life-histories of the species;
+     mosquitoes and malaria.
+
+     CRAIG, C.F. Malarial Fevers. _Osler's Mod. Med._, Vol. I, p. 392,
+     1907. Historical; distribution; malarial parasites; classification;
+     development; malarial mosquitoes; pathology; treatment, etc.
+
+     CRAIG, C.F. Studies in the Morphology of Malarial Plasmodia after
+     the Administration of Quinine and in Intracorpuscular Conjugation.
+     _Jour. Infec. Diseases_, VII, No. 2, 1910. See also same, IV, 1907,
+     pp. 108-140. Gives the evidence upon which he bases his theory of
+     the meaning of intracorpuscular conjunction.
+
+     CRAIG, C.F. The Malarial Fevers, Hemoglobinuric Fever and the Blood
+     Protozoa of Man. N.Y., 1909. A thorough consideration of the
+     subject of malaria and good discussion of the other subjects noted
+     in title. Bibliography.
+
+     DEADERICK, W.H. Malaria. Philad., 1909. The chapter on ætiology
+     treats of the transmission by mosquitoes.
+
+     HARRIS, S. Prevention of Malaria. _Jour. Amer. Med. Assn._, 53,
+     Oct. 9, 1909, pp. 1162-67. Effects of malaria, transmission by
+     mosquitoes, etc. In the discussion of the paper J.H. White
+     summarizes the fight against yellow fever in New Orleans.
+
+     HERRICK, G.W. Relation of Malaria to Agriculture and Other
+     Industries of the South. Economic losses occasioned by malaria;
+     malaria responsible for more sickness among the white population
+     than any other disease; relation to mosquitoes. _Pop. Sci. Mo._,
+     Vol. 62, Apr., 1903, pp. 521-525.
+
+     JONES, ROSS, ELLETT. Malaria. London, 1907. Small book,
+     introduction by Ross. Malaria in Greece and Italy; shows how this
+     disease contributed to the downfall of great nations.
+
+     MANNABERG, JULIUS. Malaria. In Nothnagel's _Encyclopedia of
+     Practical Med._, Amer. Ed., 1905, pp. 17-494. A very comprehensive
+     discussion of the disease and the relation of mosquitoes to the
+     malarial parasite.
+
+     MANSON, PATRICK. The Mosquito and the Malaria Parasite. _Brit. Med.
+     Jour._, Vol. II for 1898, pp. 849-853. History of the parasite in
+     the human and insect host; observations of Ross and others and
+     their meaning.
+
+     MANSON, PATRICK. Experimental Demonstration of the
+     Mosquito-malarial Theory. _Brit. Med. Jour._, Vol. 2 for 1900, pp.
+     949-951, also _Lancet_, II, 1900, pp. 923-925. Infected mosquitoes
+     sent from Rome allowed to bite men in England who had not been in
+     malarial regions. Malarial fever followed.
+
+     MANSON, PATRICK. Malarial Fever. Appendix to Vol. IX of T.C.
+     Albutt's _System of Med._, 1900. Relation of the malarial parasite
+     to the disease and to mosquitoes.
+
+     ROBERTSON, E.W. Renaming of Malaria--Anophelesis. _Va. Medical
+     Semi-monthly_, Sept. 10, 1909. Considers malaria a misnomer and
+     gives reasons for suggesting new name.
+
+     ROSS, RONALD. On Some Peculiar Pigmented Cells Found in Two
+     Mosquitoes Fed on Malarial Blood. _Brit. Med. Jour._, 1897, Dec.
+     18, p. 1786. Records in his experiments in feeding mosquitoes on
+     blood of malarial patients. Records finding the parasites in some
+     of them. Important article.
+
+     ROSS, RONALD. Pigmented Cells in Mosquitoes. _Brit. Med. Jour._,
+     1898, Feb. 26, p. 550. Further notes on them.
+
+     ROSS, RONALD. The Mosquito Theory of Malaria. Report dated
+     Calcutta, Feb. 16, 1899. Reprinted in _Pop. Sci. Monthly_, Vol. 56,
+     Nov., 1899, pp. 42-46. Tells of his investigations in India and
+     their results.
+
+     ROSS, RONALD. The Relationship of Malaria and the Mosquito.
+     _Lancet_, II, 1900, July 7, p. 4880. Observation on the
+     transmission of malaria.
+
+     ROSS, RONALD. Malaria Fever, Its Cause, Prevention and Treatment.
+     London, 1902. Chapters on malaria, mosquitoes, prevention and
+     treatment.
+
+     ROSS, RONALD. Parasites of Mosquitoes. _Jour. of Hyg._, VI, No. 2,
+     Apr., 1906. Brief review of several of his earlier papers on this
+     subject with additional notes.
+
+     SIMPSON, W.J.R. Recent Discoveries Which Have Rendered Antimalarial
+     Sanitation More Precise and Less Costly. _Brit. Med. Jour._, 1907,
+     II, pp. 1044-46. Discussion of the various factors in mosquito
+     control.
+
+     STEPHENS, J.W.W., AND CHRISTOPHERS, S.R. The Practical Study of
+     Malaria and Other Blood Parasites. London, 1908. Chapters on
+     mosquitoes, flies and ticks and their relation to diseases.
+
+     STERNBERG, G.M. The Malarial Parasite and Other Pathogenic
+     Protozoa. _Pop. Sci. Mo._, Vol. 50, 1897, pp. 628-641. Account of
+     the discovery of the malarial parasite and more recent studies on
+     it.
+
+     STERNBERG, G.M. Malaria. _Smith. Rept._, 1900, pp. 645-656. Review
+     of the experimental evidence in support of the mosquito-malaria
+     theory.
+
+     Malarial Fever. _Jour. Trop. Med. & Hyg._, II, Mar. 16, 1908, pp.
+     96-98. A list of literature mostly for the years 1906 and 1907.
+
+
+YELLOW FEVER
+
+     ADAMS, S.H. Yellow Fever, a Problem Solved. The battle of New
+     Orleans against the mosquito. _McClure's Magazine_, Vol. 27, June,
+     1906, p. 178. An interesting popular article.
+
+     CARROLL, JAMES. Yellow Fever. _Osler's Mod. Med._, Vol. II, 1907,
+     p. 736. History, ætiology, treatment. A good review of the work of
+     the Yellow Fever Com. and the results of their work.
+
+     CARROLL, JAMES. The Transmission of Yellow Fever. _Amer. Med.
+     Assn._, 40, 1905, pp. 1429-33. Shows the relation of the mosquito
+     to the disease.
+
+     CARROLL, JAMES. Yellow Fever. Lessons to be learned from the
+     present outbreak of yellow fever. _Jour. of Amer. Med. Assn._, Vol.
+     45, 1905, pp. 1079-81. Among other things recommends that
+     mosquitoes be kept from patients.
+
+     CHAILLE, S.E. The _Stegomyia_ and Fomites. _Amer. Med. Assn._, 40,
+     1903, pp. 1433-40. Concludes that the mosquito is the only proven
+     disseminator of yellow fever. Extended discussion by various
+     physicians.
+
+     DASTRE, A. The Fight Against Yellow Fever. _Smith. Rept._, 1905,
+     pp. 339-350. History of the yellow fever epidemics, its
+     geographical distribution, and the work that is being done to
+     control it.
+
+     DOTY, A.H. On the Mode of Transmission of the Infectious Agent in
+     Yellow Fever and Its Bearing upon the Quarantine Regulations. _Med.
+     Record_, Oct. 26, 1901, pp. 649-653. Review of older theories in
+     regard to the spread of yellow fever. Believes that the quarantines
+     are now unnecessary.
+
+     FINLEY, CHAS. The Mosquito Theory of the Transmission of Yellow
+     Fever and Its New Development. _Med. Record_, Jan. 19, 1901. Refers
+     to his early observations on the subject, giving extracts from some
+     of his earlier papers to show that he had long held the mosquito
+     responsible for the dissemination of yellow fever.
+
+     GOLDBERGER, JOS. Yellow Fever, Ætiology, Symptoms and Diagnosis.
+     _Yellow Fever Inst. Bull. 16, Pub. Health and Mar. Hospt. Ser._,
+     1907. Includes discussion of the relation of mosquitoes to the
+     disease.
+
+     GUITERAS, JOHN. Experimental Yellow Fever at the Inoculation
+     Station of the Sanitary Department of Havana. _Amer. Med._, Vol.
+     II, No. 21, 1901, pp. 809-817. Experiments show that all types of
+     the yellow fever from mild to severe may be produced by the bite of
+     the mosquito.
+
+     MCFARLAND, JOSEPH. Life and Work of James Carroll. Memoir read at
+     the fifth annual meeting of the Soc. of Tropical Med., 1908. Early
+     life of Carroll and his work with the Yellow Fever Com.
+
+     PARKER, H.B., BEYER, G.E., AND POTHIER, O.L. Rept. of Working Party
+     No. 1, Yellow Fever Institute. _Bull. 13, Pub. Health and Mar.
+     Hospt. Ser._, 1903. As a result of their studies they believe that
+     the disease is caused by a protozoan parasite which they name and
+     describe. Discuss the relation of mosquitoes to the disease.
+
+     REED, WALTER; CARROLL, JAMES; AND AGRAMONTE, A. Experimental Yellow
+     Fever. _Amer. Med._, July 6, 1901, pp. 15-23. Records of certain
+     experiments and their results.
+
+     REED, WALTER; CARROLL, JAMES; AND AGRAMONTE, C.A. The Ætiology of
+     Yellow Fever. A preliminary note presented at the Amer. Pub. Health
+     Assn. _Philad. Med. Jour._, Oct. 27, 1900, pp. 790-796. Also an
+     additional note in _Jour. Amer. Med. Assn._, 36, pp. 431-440, 1901.
+     Records of their experiments and a summing up of the data in regard
+     to yellow fever and the mosquito.
+
+     REED, WALTER, AND CARROLL, JAMES. The Prevention of Yellow Fever.
+     _Med. Record_, Oct. 26, 1901, pp. 441-449. History of the disease,
+     especially in U.S., results of the work of Yellow Fever Com.
+     description, life-history and habits of the mosquito, its relation
+     to yellow fever, methods of control. Important paper.
+
+     REED, WALTER. Recent Researches Concerning the Ætiology,
+     Propagation and Prevention of Yellow Fever by U.S. Army Com. _Jour.
+     Hyg._, 2, 1902, pp. 101-119. Review of work of the Yellow Fever
+     Com. and the importance of the results. Bibliography.
+
+     ROSENAN, M.J., PARKER, H.B., FRANCIS, E., AND BEYER, G.E. Rept. of
+     Working Party No. 2, Yellow Fever Institute. Experimental studies
+     in yellow fever and malaria at Vera Cruz, Mex. _U.S. Pub. Health
+     and Mar. Hospt. Ser._, May, 1904. Includes experiments and
+     observations on mosquitoes.
+
+     ROSENAN, M.J., AND GOLDBERGER, JOS. Report of Working Party No. 3,
+     Yellow Fever Institute. _Yellow Fever Inst. Bull. 15, Pub. Health
+     and Mar. Hospt. Ser._, 1906. Unsuccessful attempts to grow the
+     yellow fever parasite. Negative results in the experimental study
+     of the hereditary transmission of the yellow fever in the mosquito.
+     Appendix A gives a translation of Marchoux and Simonds' report in
+     which they report positive results in their experiments along the
+     same line.
+
+     STERNBERG, G.M. Transmission of Yellow Fever by Mosquitoes. _Smith.
+     Rept._, 1900, pp. 657-673. Review of the early theories in regard
+     to yellow fever and the work and findings of the yellow fever
+     commission.
+
+     WHITE, J.H. Yellow Fever and the Mosquito. _Jour. Amer. Med.
+     Assn._, LI, No. 26, Dec. 26, 1908. Considers both _S. calopus_ and
+     _C. pungens_. Results of early mistakes. Necessity of destroying
+     mosquito. Methods of destroying mosquito. Habits of mosquito.
+
+     Abstract of the Report of the French Yellow Fever Com. at Rio de
+     Janeiro, 1903. _Pub. Health Report, Pub. Health and Mar. Hospt.
+     Ser._, Vol. 19, Pt. I, p. 1019. A summary of their findings and
+     conclusions to the date of report.
+
+     DE YBARRA, A.M.F. Yellow Fever Again in Cuba. _Jour. Trop. Med. &
+     Hyg._, XI, Mar. 2, 1908, pp. 73-78. Cites a number of cases of
+     yellow fever within the last few years and uses them as evidence
+     to show that the disease may be transmitted in other ways than by
+     the mosquito. A strong summing up of the arguments against the
+     mosquito theory. Reprint of editorial in _Tex. Med. Jour._, Oct.,
+     1907, also follows this article.
+
+     The Extinction of Yellow Fever at Rio de Janeiro. _Lancet_, II,
+     1909, p. 404. A review of a French publication giving the results
+     of the work from 1903 to present time. In 1903 before work was
+     begun there were 584 deaths from yellow fever. In 1908 only 4, and
+     none so far in 1909. Success accredited to mosquito work and
+     general sanitation.
+
+     A Pioneer in Research on Yellow Fever. Editorial in _Brit. Med.
+     Jour._, May 30, 1908, p. 1306. Refers to the work of L.D.
+     Beauperthuy, who, in 1853, set forth the theory that yellow fever
+     was transmitted by mosquitoes.
+
+
+DENGUE
+
+     ASHBURN, P.M., AND CRAIG, C.F. Experimental Investigations
+     Regarding the Ætiology of Dengue Fever. _Jour. Infec. Diseases_,
+     Vol. V, 1907, pp. 440-475. Conclude that the disease is spread only
+     by mosquitoes.
+
+     COLEMAN, THOMAS D. Dengue. _Osler's Mod. Med._, Vol. II, 1907, p.
+     489. Ætiology, pathology, etc.; possibility of _Culex fatigans_
+     disseminating the disease.
+
+     GRAHAM, H. "The Dengue"; a Study of Its Pathology and Mode of
+     Propagation. _Jour. of Trop. Med. & Hyg._, July 1, 1903, p. 209.
+     Experiments which seem to show that dengue is transmitted by _Culex
+     fatigans_.
+
+     LEICHTENSTERN, O. Dengue. In Nothnagel's _Encyclopedia of Practical
+     Med._, Amer. Ed., 1905, pp. 720-743. Consideration of the disease
+     and its transmission.
+
+     ROSS, E.H. The Prevention of Dengue Fever. _Amer. Trop. Med. &
+     Parasit._, Vol. II, No. 3, July 1, 1908, pp. 193-195. A successful
+     campaign against the mosquitoes in Port Said in 1906 stopped the
+     outbreaks of malaria and dengue.
+
+     Dengue and Sand-flies. _Jour. Trop. Med. & Hyg._, 12, 1909, pp.
+     172-173. A note on these pages refers to the work of Dr. R. Doerr,
+     who suspects that dengue may be carried by sand-flies,
+     _Phlobotomus_, as well as by mosquitoes.
+
+
+FILARIAL DISEASES AND ELEPHANTIASIS
+
+     CHRISTOPHERS, S.R. What Is Really Known of the Cause of
+     Elephantiasis. _Ind. Med. Gaz._, Nov., 1907, p. 404. Questions
+     Manson's theory in regard to the disease being caused by filaria.
+
+     MANSON, PATRICK. Tropical Diseases. London, 1908, pp. 594-648. A
+     most comprehensive chapter on filariasis and elephantiasis.
+
+     PHALEN, J.M., AND NICHOLS, H.J. Filariasis and Elephantiasis in
+     Southern Luzon. _Phil. Jour. Sci._, Sept., 1908. _Culex
+     microannulatus_ regarded as the carrier of the filaria.
+
+     PROUT, W.T. On the Rôle of Filaria in the Production of Disease.
+     _Jour. Trop. Med. & Hyg._, Apr. 1, 1908, p. 109. Discussion of same
+     in same journal, June 1, 1908.
+
+     WHITE, DUNCAN. Filarial Periodicity and Its Association with
+     Eosinophilia. _Jour. Trop. Med. & Hyg._, 12, July 15, 1909, pp.
+     175-183. Among other things he discusses the relation of mosquitoes
+     to filarial diseases.
+
+
+LEPROSY
+
+     BRINCKERHOFF, W.R. A Note upon the Possibility of the Mosquito
+     Acting in the Transmission of Leprosy. _Pub. Health and Mar. Hospt.
+     Ser._ (general publications), 1908. Suggests the possibilities of
+     such transmission, but concludes that the probabilities are against
+     it.
+
+     GOODHUE, E.S. The Bacillus Lepræ in the Gnat and Bedbug. _Ind.
+     Med. Gaz._, Vol. XLI, Aug., 1906, p. 342. Has found this bacillus
+     in mosquitoes and bedbugs, but believes the latter is more
+     concerned in transmitting the disease.
+
+     GOODHUE, E.S. Mosquitoes and Their Relation to Leprosy in Hawaii.
+     _Amer. Med._, N.S., 2, 1907, p. 593. Suggests that mosquitoes may
+     carry the disease, also warns against danger from flies and
+     bedbugs.
+
+     HUTCHINSON, J. Mosquitoes and Leprosy. _Brit. Med. Jour._, Dec. 22,
+     1906, Vol. II, p. 1841. Evidence against the insect theory of
+     transmission of leprosy.
+
+     MUGLISTON, T.C. On a Possible Mode of Communication of Leprosy.
+     _Jour. Trop. Med._, Vol. VIII, July 15, 1905, p. 209. Suggests that
+     the itch-mite may be the carrier of leprosy. Studies on 77 lepers
+     led him to this conclusion.
+
+     SMYTH, W.R. Leprosy. _Brit. Med. Jour._, Dec. 8, 1906, Vol. II, p.
+     1670. Believes that bedbugs or some similar wingless parasite
+     conveys the disease.
+
+
+PLAGUE
+
+     BRANNERMAN, W.B. Spread of Plague in India. _Jour. of Hyg._, Vol.
+     6, No. 2, Apr., 1906, pp. 179-211. A digest of experiments made in
+     India. Discusses various ways in which the disease may be spread.
+     Review of the evidence that insects may be concerned. Bibliography.
+
+     CALVERT, W.J. Plague. _Osler's Mod. Med._, Vol. II, 1907, p. 760.
+     History; bacteriology; pathology; plague among animals;
+     transmission, etc.
+
+     HAM, B. BURNETT. Report on Plague in Queensland, 1900-1907. P. 153
+     discusses the rat-flea theory of dissemination of bubonic plague,
+     summing up the evidence of various observers, including the Indian
+     Advisory Com. and others. Considers the evidence conclusive that
+     _P. cheopis_ and possibly _C. fasciatus_ transmit plague. Other
+     pages discuss various rat fleas and their relation to plague in
+     rats.
+
+     HANKIN, E.H. On the Epidemiology of Plague. _Jour. Hyg._, 5, 1905,
+     pp. 48-83. A comprehensive discussion of the disease and its
+     spread, several pages devoted to rats and fleas; evidence for and
+     against the theory that rats and fleas are the principal carriers
+     of the disease.
+
+     HERZOG, MAX. The Plague, Bacteriology, Morbid Anatomy &
+     Histopathology, Including the Consideration of Insects as Plague
+     Carriers. Biological Laboratory Bureau of Govt. Laboratories,
+     Manila, Oct., 1904. Reviews the evidence regarding the possibility
+     of fleas carrying plague; describes a new rat flea (_Pulex
+     philippinensis_); records experiments with fleas and cites a case
+     of bubonic plague in a child in which the infection was possibly
+     carried by _Pediculi_.
+
+     MCCOY, G.W. Plague Bacilli in Ectoparasites of Squirrels. _Pub.
+     Health Reports, Pub. Health and Mar. Hospt. Ser._, Vol. XXIV, No.
+     16, Apr. 16, 1909. Experiments with fleas and lice from infected
+     squirrels demonstrating presence of plague bacilli.
+
+     MCCOY, G.W. The Susceptibility of Gophers, Field-mice and
+     Ground-squirrels to Plague Infection. _Jour. of Infec. Diseases_,
+     Vol. 6, 1909, No. 3, pp. 283-288. Gophers highly resistant,
+     field-mice moderately susceptible and ground-squirrels very
+     susceptible to plague.
+
+     MITZMAIN, M.B. Insect Transmission of Bubonic Plague: a Study of
+     the San Francisco Epidemic. _Ento. News_, 19, No. 8, 1908, pp.
+     353-359. Fleas obtained in examination of 1,800 rats. Attempt to
+     locate source of rat and flea introduction.
+
+     MORTON, F.M. Eradicating Plague from San Francisco. Report of the
+     Citizens' Health Com. and an account of its work. San Francisco,
+     1909. Discusses the epidemics, methods of transmission, methods of
+     fighting, etc.
+
+     RUCKER, W.C. Plague Among Ground-squirrels in Contra Costa Co.,
+     Cal. _Pub. Health Reports, Pub. Health and Mar. Hospt. Ser._, Aug.
+     27, 1909. Reports of human cases supposed to be connected with
+     plague among ground-squirrels. Plague among squirrels; habits,
+     methods of fighting, etc.
+
+     RUCKER, W.C. Fighting an Unseen Foe. _Sunset Mag._, XXII, No. 2,
+     Feb., 1909. Story of the fight against plague in San Francisco.
+
+     SHIPLEY, A.E. Rats and Their Animal Parasites. _Jour. Eco.
+     Biology_, Vol. III, No. 3, Oct. 28, 1908. List of species of ecto-
+     and endoparasites.
+
+     SIMPSON, W.J. A Treatise on Plague. Cambridge Univ. Press, London,
+     1906. Deals with historical, epidemiological, clinical, therapeutic
+     and preventive aspect of the disease.
+
+     THOMPSON, J.A. The Mode of Spread and Prevention of Plague in
+     Australia. _Lancet_, Oct. 19, 1907, p. 1104. Rat fleas the
+     essential factor in transmitting plague, and preventive methods
+     should be directed against the rats.
+
+     THOMPSON, J.A. On the Epidemiology of Plague. _Jour. Hyg._, Vol.
+     VI, No. 5, Oct., 1906. Methods of infection, spread, relation of
+     rats to the disease and a review of the rat-flea theory.
+     Bibliography.
+
+     VERJBITSKI, D.T. The Part Played by Insects in the Epidemiology of
+     Plague. _Jour. Hyg._, 8, 1908, No. 2, pp. 162-208. Record of
+     extensive experiments with fleas. Fleas communicated plague for
+     three days, bedbugs for five days. Interrelation of fleas, rats,
+     dogs, cats, and man. An important article translated from Russian.
+
+     WHERRY, W.B. Further Notes on the Rat Leprosy and on the Fate of
+     the Human and Rat Leper Bacillus in Flies. _Jour. Infec. Diseases_,
+     Vol. 5, No. 5, 1908. Discussion and references, experiments with
+     flies, summary, etc. More than 1,115 lepra-like bacilli were
+     counted in a single fly-speck.
+
+     WHERRY, W.B. Plague Among the Ground-squirrels of California.
+     _Jour. Infec. Diseases_, Vol. 5, No. 5, 1908, pp. 485-533. How the
+     plague was first discovered among rats, records of cases and a
+     discussion of the possible relation of this to human plague cases.
+
+     Eradicating Plague in San Francisco; Report of the Citizens' Health
+     Committee, 1909. An account of the recent outbreaks and the methods
+     of fighting them.
+
+     Report of the Indian Plague Commission, Vol. V, pp. 75-77, 1901. In
+     these pages the Commission considers the question of the
+     transference of plague by suctorial insects. It considers Simonds'
+     claims and others and believes that "suctorial insects do not come
+     under consideration with the spread of plague."
+
+     Reports on Plague Investigations in India Issued by the Advisory
+     Committee Appointed by the Sec. of State for India, the Royal
+     Society and the Lister Institute. The reports include the reports
+     of the Working Commission appointed by the Advisory Committee and
+     reports on various contributory investigations. They are published
+     in the _Jour. of Hygiene_ as "Extra Plague Numbers." All these
+     reports deal very largely with the relation of the rat and flea to
+     plague, and are commonly referred to as "Reports of Indian Plague
+     Commission." The first number, Vol. VI, Sept., 1906, contains
+     articles on "Experiments upon the Transmission of Plague by Fleas."
+     "Note on the Species of Fleas Found on Rats, _Mus rattus_ and _Mus
+     decumanus_ in Different Parts of the World." "The Physiological
+     Anatomy of the Mouth-parts and Alimentary Canal of the Indian Rat
+     Flea, _Pulex cheopis_," and other papers on the relation of rats to
+     plague. The second number, Vol. VII, July, 1907, contains articles
+     on "On the Significance of the Locality of the Primary Bubo in
+     Animals Infected with Plague in Nature," "Further Observations on
+     the Transmission of Plague by Fleas with Special Reference to the
+     Fate of Plague Bacillus in the Body of the Rat Flea,"
+     "Experimental Production of Plague Epidemics Among Animals,"
+     "Experiments in Plague Houses in Bombay," "On the External Anatomy
+     of the Indian Rat Flea and Its Differentiation from Some Other
+     Common Fleas," "A Note on Man as a Host of the Indian Rat Flea,"
+     and others on the relation of rats to plague. The third number,
+     Vol. VII, Dec., 1907, contains articles on "Digest of Recent
+     Observations on the Epidemiology of Plague" (Bibliography),
+     "Epidemiological Observations in Bombay City," "Epidemiological
+     Observations in the Villages of Wadhala, Parel, Worli in the
+     Neighborhood of Bombay Village," "General Considerations Regarding
+     the Spread of Infection, Infectivity of Houses, etc., in Bombay
+     City and Island," "Epidemiological Observations in the villages of
+     Dhand and Kasel (Punjab)." The fourth number, Vol. VIII, May, 1908,
+     contains articles on "The Part Played by Insects in the
+     Epidemiology of Plague" (see also ref. under D.T. Verjbitski),
+     "Observations on the Bionomics of Fleas with Special Reference to
+     _P. cheopis_," "The Mechanism by Means of Which the Flea Cleans
+     Itself of Plague Bacilli," "On the Seasonal Prevalence of Plague in
+     India."
+
+     See also under Fleas.
+
+
+FLEAS
+
+     BAKER, C.F. Fleas and Disease. _Science_, N.S., Vol. 22, No. 559,
+     Sept. 15, 1905, p. 340. Discusses the possibility of fleas
+     transmitting leprosy.
+
+     DOANE, R.W. Notes on Fleas, Collected on Rat and Human Hosts in San
+     Francisco and Elsewhere. _Can. Ento._, 40, 1908, pp. 303-304. Shows
+     that _Ceratophyllus fasciatus_ and _Pulex irritans_ are common on
+     both man and rats.
+
+     FOX, CARROLL. The Flea in Its Relation to Plague, with a Synopsis
+     of the Rat Fleas. _The Military Surgeon_, 24, June, 1909, pp.
+     528-537. Review of the work of the Indian Plague Commission and
+     others. Key for identification of rat fleas.
+
+     GALLI-VALERIO. The Part Played by Fleas of Rats and Mice in the
+     Transmission of Bubonic Plague. _Jour. Trop. Med._, Feb., 1902.
+     Attacks the theory that plague can be conveyed from rats to men by
+     fleas because rat fleas do not bite men.
+
+     MCCOY, G.W. _Siphonaptera_ Observed in the Plague Campaign in
+     California with a Note upon Host Transference. _Pub. Health Report,
+     Pub. Health and Mar. Hospt. Ser._, Vol. XXIV, No. 29, July 16,
+     1909. Lists of species from various hosts. Report on experiments in
+     transferring rat fleas to squirrels and squirrel fleas to rats.
+
+     MCCOY, G.W., AND MITZMAIN, M.B. An Experimental Investigation of
+     the Biting of Man by Fleas Taken from Rats and Squirrels. _Public
+     Health Report_, XXIV, No. 8, Feb. 19, 1909, pp. 189-194. Rat and
+     squirrel fleas will bite man.
+
+     MITZMAIN, M.B. Insect Transmission of Bubonic Plague. A Study of
+     the San Francisco Epidemic. _Entomological News_, Oct., 1908.
+     Source and distribution of species of fleas and brief notes on work
+     of Indian Plague Commission.
+
+     MITZMAIN, M.B. How a Hungry Flea Feeds. _Entomological News_, Dec.,
+     1908.
+
+     MITZMAIN, M.B. Some New Facts on the Bionomics of the California
+     Rodent Fleas. _Annals Ento. Soc. Amer._, III, pp. 61-82, 1910.
+
+     SHIPLEY, A.E. Rats and Their Animal Parasites. _Jour. of Economic
+     Biology_, Vol. 3, No. 3, Oct. 28, 1908. List of species ecto- and
+     endoparasites.
+
+     See also reports of Advisory Commission under Plague.
+
+
+TYPHOID FEVER
+
+     ANDERSON, J.F. The Differentiation of Outbreaks of Typhoid Fever
+     Due to Water, Milk, Flies and Contact. _Amer. Jour. Pub. Health_,
+     19, pp. 251-259. Discusses flies and typhoid.
+
+     MCCRAE, THOMAS. Typhoid Fever. _Osler's Mod. Med._, Vol. II, p.
+     70, 1907. A full discussion of this disease.
+
+     REED, WALTER; VAUGHAN, V.C., AND SHAKESPEARE, E.O. Abstract of
+     Report on the Origin and Spread of Typhoid Fever in the U.S.
+     Military Camps During the Spanish War of 1898. Washington, Govt.
+     Printing Office, 1900. Shows among other things that "flies
+     undoubtedly served as carriers of infection."
+
+     ROSEMAN, M.J., LUMSDEN, L.L., AND KASTLE, J.H. Report on Origin and
+     Prevalence of Typhoid Fever in D.C. Including reports by Stiles,
+     Goldberger and Stimson. _Bull. 35 of Hygienic Laboratory of U.S.
+     Public Health and Mar. Hospt. Ser._, 1907. (Second report in _Bull.
+     44_, 1907, includes nothing about insects.)
+
+     VEEDER, M.A. Typhoid Fever from Sources Other Than Water Supply.
+     _Med. Record_, 62, pp. 121-124, July 26, 1902. Cites several
+     instances where flies might act as the carriers of the disease.
+
+     WHIPPLE, GEO. C. Typhoid Fever, Its Causation, Transmission and
+     Prevention. N.Y., 1908. Considers that house-flies and probably
+     fruit-flies carry typhoid bacilli.
+
+
+HOUSE-FLIES; ANATOMY, LIFE-HISTORY, HABITS
+
+     FELT, E.P. Observations on the House-fly. _Jour. Eco. Ento._, III,
+     No. 1, Feb., 1910, pp. 24-26. Shows that it does not breed freely
+     in darkness.
+
+     GRIFFITH, A. The Life-history of House-flies. _Public Health_
+     (London), 21, No. 3, 1908, pp. 122-127. Study of life-history.
+     Flies require water frequently, eggs hatch in twenty-four hours,
+     larval stage four days. Each female may lay four batches of eggs.
+     Destroy manure and rubbish.
+
+     HAMER, W.H. The Breeding of Flies Summarized. _Am. Med._, 3, 1908,
+     p. 431. Habits of flies and experiments to show that they may carry
+     the germs of various diseases.
+
+     HEPWORTH, JOHN. On the Structure of the Foot of the Fly. _Quar.
+     Jour. Micro. Sci._, II, 1859, pp. 158-563. One plate showing feet
+     of different flies. A review of the older theories of how a fly was
+     able to walk on smooth surfaces.
+
+     HERMS, W.B. The Essentials of House-fly Control. _Bull. of Berkeley
+     Board of Health_, Berkeley, Cal., 1909. Recommends removing manure
+     as soon as possible and keeping it in tight bins until removed. No
+     very satisfactory insecticides have been found for use in treating
+     manure piles.
+
+     HERMS, W.B. The Berkeley House-fly Campaign. _Cal. Jour. of
+     Technology_, Vol. XIV, No. 2, 1909. Discusses the methods that have
+     been used in fighting the fly in Berkeley, Cal. Removing manure
+     regularly or keeping it in closed bins recommended.
+
+     HEWITT, C.G. A Preliminary Account of the Life-history of the
+     Common House-fly. _Mem. and Proc. Manchester Lit. Phil. Soc._,
+     1906, Vol. 51, pp. 1-4.
+
+     HEWITT, C.G. On the Bionomics of Certain Calyptrate Mucidæ and
+     Their Economic Significance with Especial Reference to Flies
+     Inhabiting Houses. _Jour. Econ. Biol._, 1907, Vol. II, pp. 79-88.
+     Character and importance of group and notes on many species.
+
+     HEWITT, C.G. Structure, Development and Bionomics of the House-fly,
+     _Muca domestica_. Part I, _Quar. Jour. Micro. Sci._, 1907, p. 395,
+     on anatomy, external and internal, and bibliography. Part II, same;
+     1908, p. 495. Breeding-habits, development and anatomy of larvæ,
+     bibliography. Part III, same; 1909, pp. 347-414. The bionomics,
+     allies, parasites, and the relations to human disease. The best
+     article on the house-fly.
+
+     HOWARD, L.O. Further Notes on the House-fly. _Bull. 10, U.S. Dept.,
+     Agric. Div. of Ento._, p. 63, 1898. Experiments to kill larvæ in
+     manure.
+
+     HOWARD, L.O. House-flies. _U.S. Dept. of Agric., Bureau of Ento.,
+     Circular No. 71_, revised ed., 1906. Methods of control of
+     house-fly and related species.
+
+     HOWARD, L.O., AND MARLATT, C.L. _Bull. 4, U.S. Dept. Agric., Div.
+     of Ento._, pp. 43-47, 1896. General account with methods of
+     controlling.
+
+     JEPSON, F.P. The Breeding of the Common House-fly During the Winter
+     Months. _Jour. Econ. Biol._, 4, 1909, pp. 78-82. Records of certain
+     experiments which show that the flies will breed in winter under
+     favorable conditions.
+
+     NEWSTEAD, R. Preliminary Report on the Habits, Life-cycle and
+     Breeding-places of the Common House-fly as Observed in the City of
+     Liverpool, with Suggestions as to the Best Means of Checking Its
+     Increase. Liverpool, Oct. 3, 1907.
+
+     NEWSTEAD, R. On the Habits, Life-cycle and Breeding-places of the
+     Common House-fly. _Ann. Trap. Med. Para._, Vol. I, No. 4, Feb. 29,
+     1908, pp. 507-520. Final report on this subject. Sums up notes on
+     life-history, habits, breeding-places, etc. Important article.
+
+     PACKARD, A.S. On the Transformation of the Common House-fly with
+     Notes on Allied Forms. _Proc. Boston Soc. Nat. Hist._, Vol. XVI,
+     1874, pp. 136-140. Life-history and anatomy.
+
+     WILCOX, E.V. Fighting the House-fly. _Country Life in America_,
+     May, 1908. Methods of controlling this pest.
+
+
+HOUSE-FLIES AND TYPHOID
+
+     AUSTEN, E.E. The House-fly and Certain Allied Species as
+     Disseminators of Enteric Fever Among the Troops in the Field.
+     _Jour. Roy. Army Med. Corps_, June, 1904. Suggests that it may
+     carry enteric fever and other diseases; method of control.
+
+     FELT, E.P. The Typhoid or House-fly and Disease. In 24th _Rept. of
+     State Ento_. in _N.Y. State Museum Bull._, No. 455, 1909. A general
+     discussion with complete bibliography.
+
+     FIRTH, R.H., AND HORROCKS, W.H. An Inquiry Into the Influence of
+     Soil, Fabrics, and Flies in the Dissemination of Enteric Infection.
+     _Brit. Med. Jour._, Vol. II, 1902, pp. 936-942. House-flies carry
+     enteric bacilli. They may pass through digestive tract and remain
+     virulent.
+
+     HAMILTON, ALICE. The Fly as a Carrier of Typhoid. _Jour. Amer. Med.
+     Assn._, 40, 1903, pp. 576-83. A study of a typhoid outbreak in
+     Chicago gives good evidence that the flies were important factors
+     in the spread of the disease.
+
+     HEWITT, C.G. The Biology of House-flies in Relation to Public
+     Health. _Royal Inst. Pub. Health Jour._, Oct., 1908.
+
+     HOWARD, L.O. A contribution to the Study of the Insect Fauna of
+     Human Excrement. _Proc. Wash. Acad. Sci._, 2, 1900, pp. 541-600.
+     Special reference to the house-fly and typhoid fever.
+
+     HOWARD, L.O. Flies and Typhoid. _Pop. Sci. Mo._, Jan., 1901, pp.
+     249-256. A popular account of several species of flies that may be
+     concerned in carrying typhoid.
+
+     KLEIN, E. Flies as Carriers of _B. typhus_. _Brit. Med. Jour._,
+     Oct. 17, 1908, pp. 1150-51. In cultures made from flies he found
+     great numbers of _B. coli communis_ and _B. typhosus_, showing that
+     flies may carry these germs.
+
+     MARTIN, A. Flies in Relation to Typhoid and Summer Diarrhea.
+     _Public Health_, 15, 1903, pp. 652-653. Believes that the house-fly
+     is largely responsible for these diseases.
+
+     REED, WALTER. _War Dept. An. Rept._, 1899, pp. 627-633. Flies the
+     cause of a typhoid outbreak in army in 1899.
+
+
+HOUSE-FLY AND VARIOUS DISEASES
+
+     BUCHANAN, R.A., GLASG, F.F., AND M.B. The Carriage of Infection by
+     Flies. _Lancet_, 173, 1907, pp. 216-218. Flies carry various germs
+     on their feet and distribute them where they walk. Must protect
+     food from contamination.
+
+     BREWSTER, E.T. The Fly. The Disease of the House. _McClure's
+     Magazine_, XXXIII; No. 5, Sept., 1909, pp. 564-568. Proposes to
+     make use of tropisms for ridding the houses of flies.
+
+     CASTELLANI, ALDO. Experimental Investigation on _Framboesia
+     tropica_ (Yaws). _Jour. of Hyg._, Vol. VII, 1907, pp. 558-599. On
+     pages 566-568 he discusses the part played by insects in
+     transmitting the disease. Gives detail of experiments conducted and
+     concludes that under certain conditions yaws may be conveyed by
+     flies and possibly other insects.
+
+     COBB, J.O. Is the Common House-fly a Factor in the Spread of
+     Tuberculosis? _Amer. Med._, 9, 1905, pp. 475-477. Believes that the
+     bacilli may enter the system through the digestive tract and that
+     flies carry them to our food.
+
+     DICKENSON, G.K. The House-fly and Its Connection with Disease
+     Dissemination. _Med. Record_, 71, 1907, pp. 134-139. Summary;
+     bibliography.
+
+     ESTEN, W.M., AND MASON, C.J. Sources of Bacteria in Milk. Starr's
+     _Agric. Ex. Stn., Conn. Bull._, 51, 1908. Shows how flies may carry
+     bacteria to milk. Table showing number of bacteria on flies from
+     various sources.
+
+     FELT, E.P. The Economic Status of the House-fly. _Jour. Eco.
+     Ento._, Vol. 2, No. 1, Feb., 1909, pp. 39-45. A summary of the
+     charges, possibilities, proofs, etc. Discussion.
+
+     GUDGER, E.W. Early Note on Flies as Transmitters of Disease.
+     _Science_, N.S. Vol. 31, Jan. 7, 1910, pp. 31-32.
+
+     HAMER, W.H. Nuisance from Flies. _London County Council Rept._ No.
+     1,138, pp. 1-10, and No. 1,207, pp. 1-6, 1908. Observations on
+     various flies and their relation to diseases.
+
+     HAYWARD, E.H. The Fly as a Carrier of Tuberculosis Infection. _N.Y.
+     Med. Jour._, 80, 1904, pp. 643-644. Tubercular bacilli pass through
+     the digestive tract of flies and remain virulent.
+
+     HOWARD, L.O. The Carriage of Disease by Flies. _Bull. 30_, N.S.,
+     pp. 39-45, _U.S. Dept. Agric, Div. of Ento._, 1901. Discussion of
+     flies as carriers of disease.
+
+     HOWARD, L.O. House-flies. _U.S. Dept. of Agric., Bureau of Ento._,
+     Cir. No. 71, revised ed., Sept. 21, 1906. Notes on the various
+     species visiting houses; habits; methods of control; regulations
+     for controlling flies in cities.
+
+     HUTCHINSON, WOODS. The Story of the Fly That Does Not Wipe Its
+     Feet. _Sat. Evening Post_, March 7, 1908.
+
+     JACKSON, DANIEL D. Conveyance of Disease by Flies Summarized.
+     _Bost. Med. & Surg. Jour._, 1908, p. 451. Disease and flies prevail
+     at same time; records over 1,000,000 bacteria to each fly caught on
+     swill-barrels.
+
+     JACKSON, DANIEL B. Pollution of New York Harbor as a Menace to
+     Health by the Dissemination of Intestinal Diseases Through the
+     Agency of the Common House-fly. Account of experiments and
+     deductions. Pamphlet issued July, 1908, by Merchants' Assn. of New
+     York.
+
+     LEIDY, JOSEPH. Flies as a Means of Communicating Contagious
+     Diseases. _Proc. Acad. Nat. Sci. Phil._, 23, 1871, p. 297. Believes
+     that flies may carry disease; refers to flies in connection with
+     gangrene and wounds.
+
+     LORD, F.T. Flies and Tuberculosis. _Bost. Med. & Surg. Jour._,
+     1904, pp. 651-654. Fly-specks may contain virulent tubercular
+     bacilli for at least fifteen days.
+
+     MAYS, THOS. J. The Fly and Tuberculosis. _N.Y. Med. Jour. & Phila.
+     Med. Jour._, 82, 1905, pp. 437-438. Believes that J.O. Cobb's data
+     as given in _Amer. Med. Jour._ is not at all conclusive.
+
+     NASH, J.C.T. A Note on the Bacterial Contamination of Milk as
+     Illustrating the Connection Between Flies and Epidemic Diarrhea.
+     _Lancet_, II, 1908, pp. 1668-69. Experiments show that milk left
+     exposed to flies soon contains many more germs than that protected
+     from them.
+
+     NASH, J.C.T. The Ætiology of Summer Diarrhea. _Lancet_, 164, 1903,
+     p. 330. Believes house-fly carries this disease because the two
+     appear and disappear together.
+
+     ROBERTSON, A. Flies as Carriers of Contagion in Yaws. _Jour. Trop.
+     Med. & Hyg._, 11, 1908, No. 14, p. 213. As a result of examinations
+     the author concludes that the house-fly is capable of carrying the
+     virus of yaws.
+
+     SANDILANDS, J.E. Epidemic Diarrhea and the Bacterial Control of
+     Food. _Jour. Hyg._, 6, 1906, pp. 77-92. Believes that house-flies
+     convey these diseases from the excrement of infected infants.
+
+     SIBTHORPE, E.H. Cholera and Flies. _Brit. Med. Jour._, Sept., 1896,
+     p. 700. Flies considered scavengers, think they thus help abate the
+     disease.
+
+     SMITH, T. The House-fly as an Agent in Dissemination of Infectious
+     Diseases. _Amer. Jour. Pub. Hyg._, Aug., 1908, pp. 312-317. Points
+     out that flies on account of their habits, are dangerous sources of
+     contamination.
+
+     SMITH, THEOBALD. The House-fly at the Bar. Merchants' Assn., New
+     York, 1909, pp. 1-48. Letters from various authorities giving their
+     opinion; quotations from various authors. Bibliography.
+
+     VEEDER, M.A. Flies as Spreaders of Sickness in Camps. _Med.
+     Record_, 54, 1898, pp. 429-430. Flies feed on typhoid excreta and
+     pass to food. Cultures made from fly tracks and excreta show many
+     bacteria present.
+
+     VEEDER, M.A. The Relative Importance of Flies and Water Supply in
+     Spreading Disease. _Med. Record_, 55, 1899, pp. 10-12. Reasons for
+     believing that flies spread disease in many instances. Burial of
+     infected typhoid material no protection but a menace.
+
+     Dangers from Flies. E.P.W. _Nature_, Vol. 29, pp. 482-483. Review
+     of an article by Dr. B. Grassi in regard to flies and various
+     diseases. Opthalmia is discussed. Flies may ingest and pass
+     unharmed eggs of various human parasites including tapeworm.
+
+
+HUMAN MYIASIS
+
+     ALLEN, CHAS. H. Demonstration of Locomotion in the Larvæ of the
+     OEstridæ. _Proc. Amer. Assn. Adv. Set._, Vol. 24, 1875, pp.
+     230-236. Larvæ taken from flesh of child, one had moved thirty-six
+     inches and one six inches.
+
+     FRENCH, G.H. A Parasite the Supposed Cause of Some Cases of
+     Epilepsy. _Canad. Ento._, 32, 1900, pp. 263-264. Larvæ of
+     _Gastrophilus_ or _Dermatobia_ in the alimentary canal supposed to
+     have caused spasms in young boy.
+
+     GILBERT, N.C. Infection of Man by Dipterous Larvæ with Report of
+     Four Cases. _Archives of Internal Med._, Oct., 1908. Historical;
+     various kinds sometimes found in man; good summary of subject.
+     Bibliography.
+
+     HARRISON, J.H.H. A Case of Myiasis. _Jour. Trop. Med. & Hyg._, XI,
+     Oct. 15, 1908, p. 305. Over 300 larvæ of _Lucilia macellaria_
+     removed from face of negro woman.
+
+     HUMBERT, FRED. _Lucilia macellaria_ Infesting Man. _Proc. U.S. Nat.
+     Museum_, 6, 1883, pp. 103-104. Records several cases in which the
+     screw-worm infested patients.
+
+     JENYUS, LEONARD. _Trans. Ento. Soc._, London, Vol. II, 1839, pp.
+     152-159. Notice of a case in which the larvæ of a dipterous insect,
+     supposed to be _Anthomyia canicularis_, Meig., were expelled in
+     large quantities from the human intestines.
+
+     KANE, E.R. A Grub Supposed to Have Traveled in the Human Body.
+     _Insect Life_, II, 1890, pp. 238-239. Larva of bot-fly taken from
+     face of boy. It had been traveling under the skin for about five
+     months.
+
+     MCCAMPBELL, E.F., AND COOPER, H.J. _Myiasis intestinalis_ Due to
+     Infection with Three Species of Dipterous Larvæ. _Jour. Amer. Med.
+     Assn._, 53, Oct. 9, 1909, pp. 1160-62. General notes on this
+     subject and a report on a case in which larvæ of three different
+     species of flies were obtained from one patient.
+
+     MEINERT, FR. _Lucilia nobilis_ Parasitic on Man. _Insect Life_, II,
+     1892, pp. 36-37. Two larvæ from the ear of a man proved to be the
+     above species.
+
+     MURTFELEDT, M.E. Hominivorous Habits of the Screw-worm in St.
+     Louis. _Insect Life_, IV, 1891, p. 200. Many larvæ of this species
+     removed from the nasal passages of a patient.
+
+     NELSON, J.B. Insects in the Human Ear. _Insect Life_, VI, 1893, p.
+     56. Two cases in which blow-fly larvæ are reported as coming from
+     the human ear.
+
+     RILEY, W.A. A Case of Pseudoparasitism by Dipterous Larvæ. _Canad.
+     Ento._, 38, 1906, p. 413. Several larvæ, species undetermined,
+     removed from back of patient.
+
+     SAY, THOMAS. On a South American Species of OEstrus Which
+     Inhabits the Human Body. _Tr. Phil. Acad. Nat. Sci._, Vol. 2, 1822,
+     pp. 353-360. Extended notes on various dipterous larvæ infesting
+     man.
+
+     SNOW, F.H. Hominivorous Habits of _Lucilia macellaria_ "The
+     Screw-worm." _Psyche_, 4, 1883, pp. 27-30. Cites observations made
+     by himself and others.
+
+     WILLISTON, S.W. The Screw-worm Fly _Compsomyia macellaria_.
+     _Psyche_, 4, 1883, pp. 112-114. Notes on this species with a
+     translation of a Spanish article by Anibalzaga in which instances
+     of this fly infesting human beings are recorded.
+
+     YOUNT, C.E., AND SUDLER, M.T. Human Myiasis from the Screw-worm
+     Fly. _Jour. Amer. Med. Assn._, Vol. 49, No. 23, 1907, p. 1912.
+     Several cases giving reference to literature, symptomatology,
+     diagnosis.
+
+
+STOMOXYS AND OTHER FLIES
+
+     AUSTEN, E.E. Blood-sucking and Other Flies Known or Likely to Be
+     Concerned in the Spread of Disease. In Albutt's and Rolleston's
+     _System of Med._, 2, 1907, pp. 169-186. A descriptive list of these
+     flies. Bibliography.
+
+     AUSTEN, E.E. Illustrations of African Blood-sucking Flies Other
+     Than Mosquitoes and Tsetse-flies. London, 1909.
+
+     NEWSTEAD, R. On the Life-history of _Stomoxys calcitrans_. _Jour.
+     Econom. Biology_, Vol. I, 1906, pp. 157-166. Describes habits and
+     life-history of larvæ and adults. Important article.
+
+     STEPHENS, J.W.W., AND NEWSTEAD, R. The Anatomy of the Proboscis of
+     Biting Flies. Part II, _Stomoxys_. _Ann. of Trop. Med. & Parasit._,
+     Vol. I, No. 2, June 15, 1907, pp. 171-182. Good anatomical paper.
+     Part I (_Glossina_) was published in mem. XVIII, 1906, Liverpool
+     School Trop. Med.
+
+     TULLOCK, F. Internal Anatomy of _Stomoxys_. _Proc. Roy. Soc._,
+     London, 77, Series B, 1906, pp. 523-531. Descriptions and drawings
+     comparing with _Glossina_.
+
+
+TSETSE-FLIES
+
+     AUSTEN, E.E. A Monograph of the Tsetse-flies. Published by order of
+     the Trustees of the British Museum, 1903.
+
+     MANSON, P. Tsetse-flies. In _Trop. Diseases_, p. 174. Description
+     of genus; table of species; distribution; reproduction, habits.
+
+     MINCHIN, E.A. Report of Anatomy of the Tsetse-fly (_Glossina
+     palpalis_). _Proc. Roy. Soc._, London, 76, Series B, 1905, pp.
+     531-547. Good account of internal anatomy of this fly, important
+     because of its relation to trypanosomiasis.
+
+     MINCHIN, E.A. The Breeding-habits of the Tsetse-fly. _Nature_, Oct.
+     25, 1906, p. 636.
+
+     MINCHIN, E.A., GRAY, A.C.H., AND TULLOCK, F.M.G. (Sleeping Sickness
+     Com.) _Glossina palpalis_ in Its Relation to _Trypanosoma
+     gambiense_ and Other Trypanosomes (Preliminary Report). _Proc. Roy.
+     Soc._, Vol. 78, 1906, pp. 242-258. Report on certain experiments in
+     feeding these flies on infected animals and in allowing supposedly
+     infected flies to feed on various animals.
+
+     NOVY, F.G. The Trypanosomes of Tsetse-flies. _Jour. Infec. Dis._,
+     III, 1906, pp. 394-411. Notes on the various species.
+
+
+TRYPANOSOMES AND TRYPANOSOMIASIS
+
+     BRUCE, DAVID. Trypanosomiasis. _Osler's Mod. Med._, Vol. I, 1907,
+     p. 460. A discussion of _Trypanosoma lewisi_, _evansi_, _brucei_,
+     _gambiensi_, and the diseases caused by them.
+
+     DUTTON, J.E., TODD, J.L., AND HARRINGTON, J.W.B. Trypanosome
+     Transmission Experiments. _Am. Trop. Med. & Parasit._, Vol. I, No.
+     2, June 15, 1907, pp. 201-229. Sections on attempts to transmit
+     trypanosomes by tsetse-flies; by other blood-sucking Arthropods,
+     etc., conclude that trypanosomes may be mechanically transmitted by
+     the bite of blood-sucking Arthropods.
+
+     HOOKER, W.A. Descriptions of Certain Trypanosomes, and Review of
+     the Present Knowledge of the Rôle of Ticks in the Dissemination of
+     Disease. _Jour. Econ. Ento._, Vol. I, No. 1, 1908, pp. 65-76. Good
+     review, tables and literature.
+
+     MINCHIN, E.A. Investigations on the Development of Trypanosomes in
+     Tsetse-flies and Other _Diptera_. _Quart. Jour. Micro. Sci._, 1908,
+     pp. 159-260.
+
+     MUSGROVE, W.E., AND CLEGG, M.T. Trypanosomes and Trypanosomiasis,
+     with Special Reference to Surra in the Philippine Islands.
+     _Biological Lab., Bull. No. 5_, Manila, 1903. Discuss flies, fleas,
+     mosquitoes, lice and ticks as possible disseminators of the
+     disease.
+
+     NOVY, T.G., MCNEAL, M.J., AND TORRY, H.M. The Trypanosomes of
+     Mosquitoes and Other Insects. _Jour. Infec. Diseases_, IV, 1907,
+     pp. 223-276. These parasites are often found in mosquitoes and
+     other insects. Bibliography.
+
+     NUTTALL, G.H.F. The Transmission of _Trypanosoma lewisi_ by Fleas
+     and Lice. _Parasitology_, Vol. I, No. 4, Dec., 1908, pp. 296-301.
+     This rat trypanosome is transmitted by fleas and lice.
+
+     OLD, J.E.S. Contribution to the Study of Trypanosomiasis and to the
+     Geographical Distribution of Some of the Blood-sucking Insects,
+     etc. _Jour. Trop. Med. & Hyg._, 12, Jan. 15, 1909, pp. 15-22. Notes
+     on blood-sucking _Diptera_ and ticks.
+
+     ROGERS, LEONARD. The Transmission of the _Trypanosoma evansi_ by
+     House-flies and Other Experiments Pointing to the Probable Identity
+     of Surra of India and Nagana or Tsetse-fly Disease of Africa.
+     _Proc. Roy. Soc._, Vol. LXVIII, 1901, pp. 163-170.
+
+     THIMM, C.A. Bibliography of Trypanosomiasis; embracing original
+     papers published prior to April 1909, and references to works and
+     papers on tsetse-flies. London, 1909.
+
+     TODD, J.L. A Note on Recent Trypanosome Transmission Experiments.
+     _Jour. Trop. Med. & Hyg._, 12, Sept., 1909, p. 260. Show that they
+     develop in _G. palpalis_ when taken from their mammal host at the
+     proper stage of development.
+
+     WOODCOCK, H.M. The Hæmoflagellates: a Review of Present Knowledge
+     Relating to the Trypanosomes and Allied Forms. _Quar. Jour. Micro.
+     Sci._, Vol. 50, 1906, pp. 151-331. Characteristics; mode of
+     infection; effects on host; biological considerations; life-cycle,
+     etc. _Spirochaetæ_; bibliography. Important article.
+
+     Trypanosomiasis and Sleeping Sickness. _Jour. Trop. Med. & Hyg._,
+     II, pp. 146-147, 162, 179-180, 196. List of recent literature.
+
+
+SLEEPING SICKNESS
+
+     BAGSHAWE, A.G. Recent Advances in Our Knowledge of Sleeping
+     Sickness. _Lancet_, II, 1909, pp. 1193-97. A summing up of the
+     important discoveries of the preceding year.
+
+     HEARSEY, H. Sleeping Sickness. _Jour. Trop. Met. & Hyg._, 12, Sept.
+     1, 1909, pp. 263-264. Report on work accomplished particularly in
+     relation to the distribution of _Glossina_ and other biting flies.
+
+     JARVIS, C. Sleeping Sickness. _Internat. Clinics_, Vol. II, 1904,
+     pp. 37-44. Shows the relation of the tsetse-fly to this disease.
+
+     LANKESTER, E.R. The Sleeping Sickness. _Quar. Review_, July, 1904,
+     p. 113. Discovery and early history; the fly, the parasite; other
+     related parasites. Relation of parasites to their hosts.
+
+     MINCHIN, E.A. The Ætiology of Sleeping Sickness. _Nature_, Nov. 15,
+     1906, pp. 56-59.
+
+     WOLLASTON, A.F.R. Amid the Snow Peaks of the Equator: a
+     Naturalist's Explorations Around Ruwenzori, with an _Account of the
+     Terrible Scourge of Sleeping Sickness_. _Nat. Geo. Mag._, XX, No.
+     3, Mar., 1909. Abstracted from "From Ruwenzori to the Congo" by
+     above author.
+
+     Reports of the Sleeping Sickness Com. of the Royal Society, I to
+     IX, 1903 to 1908. Studies and experiments with the trypanosomes and
+     flies concerned in this disease. Later articles by this commission
+     are to be found in the _Pro. Royal Soc._, Series B, LXXXI and
+     LXXXII.
+
+     Sleeping Sickness Bureau Bulletins, 1 to 14, 1908-1910. Records of
+     studies and experiments with trypanosomes and tsetse-flies, etc.
+
+     Transmission of Sleeping Sickness. Editorial in _Jour. Amer. Med.
+     Assn._, 53, Oct. 2, 1909, pp. 1104-05. Reviews recent experiments
+     and studies.
+
+
+ROCKY MOUNTAIN FEVER AND TICKS
+
+     ANDERSON, J.F. Spotted Fever (Tick Fever) of the Rocky Mountains.
+     _Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull. 14_, 1903.
+     Distribution, ætiology, etc. Believes that ticks are responsible
+     for the transmission of the disease.
+
+     COOLEY, R.A. Preliminary Report on the Wood-tick. _Bull. 75, Mont.
+     Ex. Stn._, 1908. Sums up Ricketts' finding; notes on life-history
+     in laboratory and field.
+
+     KING, W.W. Experimental Transmission of Rocky Mountain Fever by
+     Means of the Tick. Preliminary note. _Pub. Health and Mar. Hospt.
+     Ser._, 21, July 27, 1906, pp. 863-864. Conveyed this fever from one
+     guinea-pig to another by means of the tick.
+
+     RICKETTS, H.T. The Transmission of Rocky Mountain Fever by the Bite
+     of the Wood-tick (_Dermacentor occidentalis_). _Jour. Amer. Med.
+     Assn._, Vol. 47, Aug., 1906, p. 358. Guinea-pig successfully
+     inoculated by means of tick.
+
+     RICKETTS, H.T. The Rôle of the Wood-tick (_Dermacentor
+     occidentalis_) in Rocky Mountain Spotted Fever. _Jour. Amer. Med.
+     Assn._, Vol. 49, July 6, 1907, pp. 24-27. Notes on experiments
+     conducted and studies made. Takes position that these experiments
+     connect the tick with the transmission of the fever.
+
+     ROBINSON, A.A. Rocky Mountain Spotted Fever. _Med. Rec._, Nov. 28,
+     1908. Occurrence and distribution of the disease; review of the
+     various theories in regard to its transmission. P.E. Jones of Salt
+     Lake believes it is transmitted by mosquitoes.
+
+     STILES, C.W. A Zoölogical Investigation Into the Cause,
+     Transmission and Source of Rocky Mountain Spotted Fever. _Hyg. Lab.
+     Pub. Health and Mar. Hospt. Ser., Bull. 20_, 1905. Does not find
+     the parasite that had been recorded by others, and finds no
+     evidence to indicate that the ticks transmit the disease.
+
+     WILSON, L.B., AND CHANNING, W.M. Studies in _Pyroplasmosis hominis_
+     (Spotted Fever or Tick Fever of the Rocky Mountains). _Jour. Infec.
+     Diseases_, 1, 1904, pp. 31-57. Evidence that the disease is
+     transmitted solely by means of the ticks.
+
+
+TICKS AND VARIOUS DISEASES
+
+     BANKS, NATHAN. Tick-borne Diseases and Their Origin. _Jour. Eco.
+     Ento._, Vol. I, No. 3, 1908, pp. 213-215. Shows how ticks may
+     become important disease-carriers by changing their hosts as the
+     normal host is exterminated, or for other reasons.
+
+     BANKS, NATHAN. A Revision of the Ixodoidea or Ticks of the United
+     States. _Tech. Series No. 15, Bull. of Bureau of Ento., U.S. Dept.
+     Agric._, 1908. Structure, life-history, classification, catalogue,
+     bibliography.
+
+     BARBER, C.A. The Tick Pest in the Tropics. _Nature_, 52, 1895, pp.
+     197-200. Direct and indirect effects of ticks on their hosts.
+
+     CHRISTY, C. _Ornithodoros moubata_ and Tick Fever in Man. _Brit.
+     Med. Jour._, Vol. II, 1903, p. 652. Relation of the tick to
+     _Filaria perstans_.
+
+     DUTTON, J.E., AND TODD, J.L. The Nature of Human Tick Fever in the
+     Eastern Part of the Congo Free State with Notes on the Distribution
+     and Bionomics of the Tick. Liverpool School of Tropical Medicine.
+     _Memoir_, 17, Nov., 1905, pp. 1-18.
+
+     HOOKER, W.A. A Review of the Present Knowledge of the Rôle of Ticks
+     in the Transmission of Disease. _Jour. Eco. Ento._, Vol. I, No. 1,
+     1908, p. 65. Review of the subject; table showing zoölogical
+     position of parasites transmitted by ticks. Table showing
+     zoölogical position of ticks.
+
+     HOOKER, W.A. Life-history, Habits and Methods of Study of the
+     Ixodoidea. _Jour. Eco. Ento._, Vol. 1, No. 1, 1908, p. 34. Notes on
+     several species, especially _M. annulatus_. Host relationship;
+     adaptations as factors in host relationship; mating; geographical
+     distribution; methods of breeding, etc.
+
+     HOOKER, W.A. Some Host Relations of Ticks. _Jour. Eco. Ento._, Vol.
+     2, No. 3, 1909, p. 251. Notes on ticks found on various hosts.
+
+     HUNTER, W.D., AND HOOKER, W.A. Information Concerning the North
+     American Fever Tick with Notes on Other Species. _Bull. 72, Bureau
+     of Ento._, 1907. Life-history, host relation, etc., of fever tick;
+     classification and notes on other species; bibliography divided
+     into sections.
+
+     LOUNSBURY, C.P. Habits and Peculiarities of Some South African
+     Ticks. _Rept. of the Brit. Assn. for the Advancement of Sci._, 1905
+     (South Africa), pp. 282-291.
+
+     MCCRAE, THOMAS. Relapsing Fever. _Osler's Mod. Med._, Vol. II, p.
+     245, 1907. Ætiology, symptoms, treatment, etc. (Apparently
+     communicated by blood-sucking insects.)
+
+     NEWSTEAD, R. On the Pathogenic Ticks Concerned in the Distribution
+     of Diseases in Man. _Brit. Med. Jour._, II, 1905, pp. 1695-97.
+     Classification and habits, particularly of _Ornithodoros moubata_.
+
+     NUTTALL, G.H.F. The Ixodoidea or Ticks. _Jour. of Roy. Inst. of
+     Pub. Health_, 1908. List of disease-bearing ticks. Position of
+     ticks, classification. Biology. Preventive measures.
+
+     NUTTALL, G.H.F. Piroplasmosis. _Jour. Roy. Inst. of Pub. Health_,
+     1908. What piroplasma are; diseases produced by them. Biology.
+
+     NUTTALL, GEO. F., and co-workers. _Canine Piroplasmosis_, Parts I
+     to VI. _Jour. Hyg._, Vol. 4, No. 2, Apr., 1904, to Vol. 7, No. 2,
+     Apr., 1907. A thorough discussion of the disease, the parasite
+     which causes it and the ticks which convey it.
+
+     POCOCK, R.I. Ticks. In Albutt and Rolleston's _System of Med._, II,
+     1907, pp. 187-203. Classification; description of the best-known
+     pathogenic species. Extended bibliography.
+
+     SKINNER, B. Preliminary Note on Ticks Infecting the Rats Suffering
+     from the Plague. _Brit. Med. Jour._, Vol. II, 1907, p. 457. Records
+     taking tick on a plague-sick rat and finding bacilli similar to
+     plague bacilli in connection with it.
+
+     SMITH, T., AND KILBORNE, F.L. Texas Fever. _U.S. Dept. Agric.
+     Bureau of Animal Industry, Bull. No. 1_, 1893. Records of the
+     experiments showing disease to be transmitted by ticks.
+
+     WELLMAN, F.C. Preliminary Note on Some Bodies Found in
+     Ticks--_Ornithodoros moubata_--Fed on Blood Containing Embryos of
+     Filaria. _Brit. Med. Jour._, July 20, 1907, p. 142. Believes that
+     _F. perstans_ is conveyed from man to tick and from tick to man.
+
+
+KALA-AZAR AND BEDBUGS
+
+     GIRAULT, A.A. The Indian Bedbug and Kala-azar Disease. _Sci._,
+     N.S., Vol. XXV, 1907, p. 1004. Indian bedbug is _C. rotundatus_
+     Sig. Its distribution. Summary of Dr. Patton's paper on
+     "Preliminary Report on the Development of the Leishman-Donovan Body
+     in the Bedbug."
+
+     PATTON, W.S. The Development of the Leishman-Donovan Parasite in
+     _Cimex rotundatus_. _Scientific Mem. of Gov. of India_, Nos. 27 and
+     31, 1907. Traces the development of this parasite; believes that
+     the bedbug is concerned in transmitting this disease.
+
+     See also Manson's _Tropical Diseases_, pp. 178-190.
+
+
+TEXT OR REFERENCE BOOKS IN WHICH THE RELATION OF INSECTS TO VARIOUS
+DISEASES IS DISCUSSED
+
+     ABBOTT, A.C. Hygiene of Transmissible Diseases. Phil., 1899.
+     Causes, modes of dissemination, prevention, treatment of infectious
+     and contagious diseases.
+
+     ALLBUTT, T.C., AND ROLLESTON, H.D. A System of Medicine. London,
+     1907. Vol. II, Pt. II, contains sections on tropical diseases;
+     animal parasites and the diseases they carry and zoölogical
+     articles dealing with Protozoa, mosquitoes, flies and ticks. All
+     articles have bibliographies, some of them quite extensive.
+
+     BALFOUR, ANDREW. Review of Recent Advances in Tropical Medicine.
+     Supplement to _Third Rept. Wellcome Research Lab._, London, 1908.
+     Notes, extracts and references in regard to important articles
+     during the preceding few months.
+
+     DANIELS, C.W. Studies in Laboratory Work, 2d ed., London, 1907. A
+     good discussion of animal parasites in the blood and blood-plasma;
+     development of malarial parasites in mosquitoes; flies, fleas,
+     lice, bedbugs, ticks, etc.
+
+     JACKSON, C.W. Tropical Medicine. Phil., 1907. Discusses diseases
+     due to bacteria and the parasites and uncertain causes. Splendid
+     recent summary of the various ways in which the different diseases
+     are disseminated.
+
+     LANGFELD, MILLARD. Introduction to Infectious and Parasitic
+     Diseases, Including Their Causes and Manner of Transmission. Phil.,
+     1907. Chapters on infection, animal parasites, avenues of exit and
+     portals of entry of infectious agents and parasites into the body.
+
+     MANSON, PATRICK. Lectures on Tropical Diseases. London, 1905.
+     Delivered at Cooper Medical College, 1905. Discusses several of
+     these diseases. Last chapter on problems in tropical medicine.
+
+     MANSON, PATRICK. Tropical Diseases. London, 1907, Diseases of the
+     tropics discussed in a very comprehensive manner. Considerable
+     attention given to the part played by insects in the transmission
+     of many of the diseases.
+
+     METCHNIKOFF, E. Immunity in Infectious Diseases. (Trans. from the
+     French by F.G. Binnie.) Cambridge, 1905. Splendid discussion of
+     various kinds of immunity. Insects referred to occasionally.
+
+     OSLER'S _Modern Medicine_. Vol. I, 1907, Pt. VI, Diseases Caused by
+     Protozoa. Part VII, Diseases Caused by Animal Parasites. Vol. II,
+     1907, Infectious Diseases. Vol. III, Infectious Diseases (cont.).
+     One of the best and most modern text-books; the volumes noted above
+     contain many references to the relation of insects to the
+     particular diseases under discussion.
+
+     PARK, W.H. Pathogenic Micro-organisms, Including Bacteria and
+     Protozoa. N.Y., 1908. These organisms comprehensively treated.
+
+     RICKETTS, H.T. Infection, Immunity and Serum Therapy. Chicago,
+     1906. Chapters on parasitism, infection, contagion, immunity,
+     various diseases, etc.
+
+     SCHEUBE, B. The Diseases of Warm Countries: a Handbook for Medical
+     Men. Trans. from Ger. by Pauline Falcke, London, 1903. Sections on
+     general infectious diseases, diseases caused by animal parasites,
+     etc. Good bibliography of each disease treated.
+
+     SIMPSON, W.J.R. The Principles of Hygiene as Applied to Tropical
+     and Subtropical Climates. London, 1908. Occasional references to
+     flies and mosquitoes as carriers of disease. Chapter XV deals with
+     malaria and other diseases caused by mosquitoes.
+
+     WILSON, J.C. Modern Clinical Medicine; Infectious Diseases. New
+     York and London, 1905. Chapters on yellow fever, malarial diseases
+     and plague; contains references to the relation of insects to these
+     diseases.
+
+
+MISCELLANEOUS ARTICLES
+
+     BALFOUR, ANDREW. Further Observations on Fowl Spirochætosis. _Jour.
+     Trop. Med. & Hyg._, 12, Oct. 1, 1909, pp. 285-289. Ticks and lice
+     may carry this disease.
+
+     CHITTENDEN, F.H. Harvest-mites or "Chiggers." _Circular 77, U.S.
+     Dept. Agric. Bur. Ento._, 1906, pp. 1-16. Descriptions of these
+     pests and their habits. Remedies.
+
+     DOTY, A.H. The Means by Which Infectious Diseases Are Transmitted.
+     _Amer. Jour. of Med. Sci._, 138, July, 1909, pp. 30-39. Flies and
+     mosquitoes as disseminators of disease briefly discussed.
+
+     DUNCAN, F.M. Industrial Entomology: the Economic Importance of a
+     Study of Insect Life. _Jour. Roy. Soc. Arts_, May 22, 1908, pp.
+     688-696. A very interesting review of the subject of insects and
+     disease.
+
+     FLEXNER, SIMON. _Science_, N.S., Vol. 27, No. 682, Jan. 24, 1908,
+     pp. 133-136. On these pages the author discusses relation of
+     bacteria and Protozoa to human diseases.
+
+     GOLDBERGER, JOS., AND SHAMBERG, J.F. Epidemic of an _Utricaroid
+     dermatitis_ Due to a Small Mite (_Pediculoides ventricosus_) in the
+     Straw of Mattresses. _Pub. Health Rept., Pub. Health and Mar.
+     Hospt. Ser._, July 9, 1909, Vol. XXIV, No. 28. Experiments showed
+     that a certain skin disease occurring during summer was due to this
+     mite.
+
+     GORGAS, W.C. The Part Sanitation Is Playing in the Construction of
+     the Panama Canal. _Jour. Amer. Med. Assn._, 53, Aug. 21, 1909, pp.
+     597-599. Shows the changes that have been brought about by modern
+     sanitation and the destroying of the mosquitoes' breeding-places.
+
+     HOWARD, L.O. Hydrocyanic-acid Gas Against Household Insects.
+     _Circular 46, U.S. Dept. Agric., Div. of Ento._, 1902. Directions
+     for handling this dangerous gas.
+
+     KING, A.F.G. Insects and Disease; Mosquitoes and Malaria. _Pop.
+     Sci. Mo._, XXIII, 1883, pp. 644-658. Extended article in which the
+     author sums up the observations which led him to believe that
+     malaria and other diseases were transmitted by the mosquito. One of
+     the earliest articles on this subject; refers to an article in _New
+     Orleans Med. & Surg. Jour._, Vol. IV, 1848, pp. 563-601, by Josiah
+     Nott, who maintained that yellow fever was carried by mosquitoes.
+
+     MANSON, PATRICK. Recent Advances in Science and Their Bearing on
+     Medicine and Surgery. _Jour. Trop. Med. & Hyg._, XI, pp. 337-338,
+     Sept. 16, 1908. Discussion of parasites and disease and their
+     methods of dissemination.
+
+     NEWSTEAD, R., DUTTON, J.E., AND TODD, J.L. Insects and Other
+     Arthropoda Collected in the Congo Free State. _Ann. Trop. Med. &
+     Parasit._, Vol. 1, No. 1, Feb. 1, 1907, pp. 3-100. An interesting
+     paper giving notes on many insects that cause or carry disease.
+
+     NUTTALL, G.H.F. Spirochætosis in Man and Animals. _Jour. of Roy.
+     Inst. of Pub. Health_, 1908. Why Spirochætes should be regarded as
+     Protozoa. Classification; list of blood-inhabiting forms; relapsing
+     fevers; transmission by ticks and other Arthropods.
+
+     O'CONNELL, M.D. The Oversea Transport of Insect-borne Disease.
+     _Jour. Trop. Med. & Hyg._, XI, 43, Feb. 1, 1908. Refers to article
+     in same journal (Jan. 15) and points out that malaria is very
+     likely to be transmitted by mosquitoes in this way.
+
+     OSBORN, HERBERT. Insects Affecting Domestic Animals. _U.S. Dept. of
+     Agric., Div. of Ento., Bull. No. 5_, N.S., 1896. Discusses the
+     various insect pests of man and domestic animals Host lists.
+     Bibliography.
+
+     RICKETS, H.T., AND WILDER, R.M. The Typhus Fever of Mexico. _Jour.
+     Amer. Med. Assn._, LIV, No. 6, Feb. 5, 1910, p. 463. Believes this
+     disease is transmitted by insects, probably lice.
+
+     RITCHIE, JAMES. A Review of Current Theories Regarding Immunity.
+     _Jour. Hyg._, 2, 1902, pp. 215-285, and pp. 452-464. Discussion of
+     various theories. Bibliography.
+
+     SHIPLEY, A.E. On the Relation of Certain Cestode and Nematoda
+     Parasites to Bacterial Disease. _Jour. of Eco. Biol._, 4, 1909, pp.
+     61-71. Shows that these parasites may often cause serious diseases
+     by opening the way for malignant germs.
+
+     WARD, H.B. Spirochetes and Their Relationship to Other Organisms.
+     _Amer. Nat._, 42, 1908, No. 498, pp. 374-387. Still undecided as to
+     whether they belong with bacteria or Protozoa, probably the latter.
+
+     WARD, H.B. The Relation of Animals to Disease. _Science_, N.S., 22,
+     1905, pp. 193-203. An interesting, comprehensive review of the
+     subject.
+
+     WARD, HENRY B. Relation of Animals to Disease. _Transactions of
+     Amer. Micro. Soc._, Vol. 27, 1907, pp. 5-20. The various ways in
+     which animals may produce or carry disease.
+
+     The Oversea Transport of Insect-borne Diseases. Editorial in
+     _Jour. Trop. Med. & Hyg._, XI, Jan. 15, 1908, pp. 22-23. Points out
+     the danger of yellow fever, plague and other diseases being borne
+     overseas by infected insects.
+
+     The Society for the Destruction of Vermin. Editorial in _Jour.
+     Trop. Med. & Hyg._, XI, Apr. 15, 1908, p. 124. Tells of
+     organization of such society and its purposes.
+
+
+
+
+INDEX
+
+
+  Adams, S.H., 132.
+
+  Advisory Committee, 146.
+
+  Agramonte, Dr. Aristides, 123.
+
+  Alimentary canal, fly larvæ in, 49.
+
+  Amoeba, 19.
+
+  Anopheles,
+    adults, 91;
+    eggs, 92;
+    habits of adults, 94;
+    larvæ, 78, 79, 93;
+    pupæ, 93;
+    resting position, 92;
+    species in U.S., 92.
+
+  Anthrax, 44;
+    and flies, 70.
+
+  Arthropoda, 26.
+
+  Asexual reproduction, 111.
+
+
+  Bacillus,
+    anthracis, 44;
+    icteroides, 124;
+    lepræ, 171;
+    pestis, 150.
+
+  Bacillus carriers, 66.
+
+  Back-swimmers, 100.
+
+  Bacteria, 15;
+    saprophytic and parasitic, 17;
+    effect on host, 18;
+    dissemination, 18.
+
+  Bedbugs, 54, 147.
+
+  Banks, Nathan, 34.
+
+  Bell-animalcule, 22.
+
+  Berne, 51.
+
+  Birds as enemies of mosquitoes, 99.
+
+  Black-flies, 46.
+
+  Blackheads, 35.
+
+  Blow-flies, 48.
+
+  Blue, Dr. Rupert, 143.
+
+  Blue-bottle flies, 48.
+
+  Bot-flies, 50.
+
+  Break-bone fever, 169.
+
+  Breeze-fly, 44.
+
+  Buffalo-gnats, 46.
+
+
+  Calliphora vomitoria, 48.
+
+  Camphor, for mosquitoes, 102.
+
+  Cancer, 36.
+
+  Carroll, Dr. James, 123.
+
+  Castor-bean tick, 27.
+
+  Cattle tick, 29.
+
+  Cedar oil, for mosquitoes, 102.
+
+  Ceratophyllus,
+    faciatus, 153;
+    acutus, 156.
+
+  Cesspools, 72.
+
+  Chigger, 53.
+
+  Chigger-flea, 53.
+
+  Chigo, 30, 39.
+
+  Chigoe, 53.
+
+  Cholera, 68.
+
+  Chrysomyia macellaria, 47.
+
+  Cimex,
+    lectularis, 54;
+    rotundatus, 173.
+
+  Contagious diseases, 8.
+
+  Conjugation, 20.
+
+  Cooley, Prof. R.A., 33.
+
+  Craig, Dr. C.F., 118.
+
+  Ctenocephalus,
+    canis, 154;
+    felis, 154.
+
+  Culex,
+    fatigans, 96, 170;
+    pipiens, 98.
+
+
+  Dengue, 169.
+
+  Dermatobia cyaniventris, 51.
+
+  Dermatophilus penetrans, 53.
+
+  Diarrhea, 69.
+
+  Diptera, 43.
+
+  Diving beetles, 100.
+
+  Dragon-flies, 99.
+
+  Dysentery, 20.
+
+
+  Eggs,
+    of flies, 63;
+    of mosquitoes, 77;
+    of Anopheles, 92.
+
+  Egyptian opthalmia, 52.
+
+  Elephantiasis, 164.
+
+  Enemies of mosquitoes, 97.
+
+  Enteritis, 69.
+
+  Euglena, 21.
+
+  Eye-worm, 12.
+
+
+  Face-mite, 35.
+
+  Fighting mosquitoes,
+    adults, 101;
+    larvæ, 103.
+
+  Fiji Islands, Anopheles in, 117.
+
+  Filaria bancrofti, 164.
+
+  Finlay, Dr. Charles, 124.
+
+  Fish, 100.
+
+  Flagella, 20.
+
+  Fleas, 52;
+    and plague, 142, 145, 147;
+    structure and habits, 151;
+    common species, 153;
+    on ground squirrels, 156;
+    remedies for, 157.
+
+  Flies, 43;
+    and typhoid, 65;
+    specks, 66;
+    and various diseases, 68.
+
+  Flesh-flies, 48.
+
+  Fumigating for mosquitoes, 102.
+
+
+  Gad-fly, 43.
+
+  Glossina palpalis, 163.
+
+  Golgi, Camillo, 109.
+
+  Grassi, Prof. G.B., 118.
+
+  Gray-flies, 47.
+
+  Ground squirrels and plague, 155.
+
+  Guinea-worm, 11.
+
+
+  Hæmamoeba, 109.
+
+  Hæmatobia, 45.
+
+  Hæmosporidiida, 24.
+
+  Hæmotopinus spinulosus, 55.
+
+  Harvest-mite, 37.
+
+  Havana, yellow fever in, 131.
+
+  Hawaii, mosquitoes in, 98.
+
+  Hemiptera, 54.
+
+  Homalomyia canicularis, 49.
+
+  Hoplopsyllus anomalus, 156.
+
+  Horse bot-flies, 50.
+
+  House-flies, 57;
+    structure, 59;
+    how they carry bacteria, 62;
+    life-history and habits, 63;
+    fighting, 71;
+    and typhoid, 65.
+
+  Horse-flies, 43.
+
+  Howard, Dr. L.O., 59, 73.
+
+  Hyperparasitism, 3.
+
+
+  Immunity, 5.
+
+  Indian Plague Commission, 144.
+
+  Infectious diseases, 8.
+
+  Infusoria, 22.
+
+  Insects,
+    cause or carry disease, 40;
+    numbers, 40;
+    annual loss caused by, 41;
+    how they carry disease germs, 55.
+
+  Irrigating ditches, 104.
+
+  Itch-mite, 36.
+
+
+  Jackson, Dr. D.D., 67.
+
+  Jennings, 22.
+
+  Jiggers, 38, 53.
+
+  Jigger-flea, 53.
+
+
+  Kala-azar, 173.
+
+  Kerosene, 104.
+
+  Koch, 44.
+
+
+  Læmopsylla cheopus, 153.
+
+  Lamprey-eel, 2.
+
+  Lancisi, J.M., 107.
+
+  Larvæ,
+    of flies, 64;
+    of mosquitoes, 78.
+
+  Laveran, A., 108.
+
+  Laverania, 109.
+
+  Lazear, Dr. Jessie W., 123.
+
+  Leeuwenhoek, Anton von, 22.
+
+  Lepra bacillus, 36.
+
+  Leprosy, 36, 70, 171.
+
+  Lice, 54.
+
+  Linnæus, 76.
+
+  Little house-fly, 49.
+
+  Lock-jaw, 18.
+
+  Low, Dr. A., 118.
+
+  Lucilia spp., 48.
+
+  Lugger, Prof. Otto, 38.
+
+
+  Malaria,
+    early theories in regard to, 106;
+    parasite that causes, 108;
+    life history of parasite, 109;
+    parasite in mosquito, 113;
+    summary, 117;
+    experiments, 118.
+
+  Maggots, 63.
+
+  Malta or Mediterranean fever, 171.
+
+  Mange, 37.
+
+  Manure-fly, 59.
+
+  Manson, Sir Patrick, 112, 123.
+
+  Mastigophora, 20.
+
+  Melanin, 110.
+
+  Micrococcus melitensis, 171.
+
+  Microbes, 10.
+
+  Mites, 26, 35.
+
+  Mosquito, 76;
+    abdomen, 86;
+    adults, 81;
+    Anopheles, 91;
+    how they bite, 84;
+    effect of bite, 87;
+    blood, 90;
+    how they breathe, 89;
+    classification, 91;
+    and dengue, 169;
+    eggs, 77;
+    and elephantiasis, 164;
+    enemies, 77;
+    fighting, adults, 101;
+    larvæ, 103;
+    larvæ, 78;
+    and malaria, 106;
+    malarial parasite in, 113;
+    mouth-parts, 83;
+    other species, 96;
+    pupæ, 80;
+    salivary glands, 87;
+    thorax, 85;
+    and yellow fever, 94, 120.
+
+  Mouth-parts,
+    of fly, 60;
+    of mosquito, 83.
+
+  Mus,
+    norvegicus, 154;
+    rattus, 154.
+
+
+  Nanga, 45.
+
+  Nematodes, 164.
+
+  New Orleans, yellow fever in, 120, 132.
+
+  Noctiluca, 21.
+
+  No-see-ums, 46.
+
+
+  Ochromyia anthropophaga, 49.
+
+  Oil of citronella, 102.
+
+  Oil of pennyroyal, 102.
+
+  Oriental sore, 174.
+
+  Ornithodorus moubata, 34.
+
+  Oscinidæ, 52.
+
+  Otospermophilus beecheyi, 155.
+
+  Oxwarbles, 50.
+
+
+  Panama Canal zone, 135.
+
+  Paramoecium, 22.
+
+  Parasite,
+    defined, 1;
+    classes of, 4;
+    in new regions, 5;
+    diseases caused by, 7;
+    effect on host, 9;
+    relation to host, 14.
+
+  Parasitism, 3.
+
+  Pasteur, L., 44.
+
+  Pearls, 13.
+
+  Piroplasma bigeminum, 29.
+
+  Plague,
+    early history of, 142;
+    fleas that transmit, 153;
+    and flies, 70;
+    and ground squirrels, 155;
+    how combatted in San Francisco, 143;
+    results of other investigations, 150;
+    Verjbitski's experiments, 147;
+    work of Indian Plague Commission, 146.
+
+  Plasmodium, 109.
+
+  Protozoa, 19;
+    classes of, 20.
+
+  Proboscis,
+    of fly, 60;
+    of mosquito, 80.
+
+  Privies, 72.
+
+  Privy-fly, 59.
+
+  Pseudopodia, 20.
+
+  Psoroptes communis, 37.
+
+  Pulex irritans, 154.
+
+  Punkies, 46.
+
+  Pupæ,
+    of house-flies, 64;
+    of mosquitoes, 80.
+
+  Pyrethrum, 102.
+
+
+  Rats,
+    and plague, 143, 145;
+    species of, 154.
+
+  Red-bugs, 38.
+
+  Reed, Dr. Walter, 123.
+
+  Relapsing fever, 21, 33.
+
+  Rhizopoda, 20.
+
+  Ricketts, Dr. H.F., 32.
+
+  Rio de Janeiro, yellow fever in, 137.
+
+  Rocky Mountain spotted fever, 32.
+
+  Ross, Ronald, 112.
+
+  Rucker, Dr. W.C., 143.
+
+
+  Sacculina, 2.
+
+  Salivary glands, 84, 87.
+
+  Salt marshes, 97, 105.
+
+  Sambon, Dr. L.W., 118.
+
+  Sand-fleas, 53.
+
+  Saprophytic bacteria, 17.
+
+  Sarcophaga spp., 48.
+
+  Sarcoptes scabiei, 37.
+
+  Scab, 37.
+
+  Screw-worm, 47.
+
+  Seed-ticks, 27, 30.
+
+  Sheep bot-flies, 51.
+
+  Simmond, Dr. P.L., 145.
+
+  Siphonaptera, 52.
+
+  Skinner, Dr. H., 159.
+
+  Sleeping sickness, 21, 161.
+
+  Slipper animalcule, 22.
+
+  Small-pox, 70.
+
+  Smith, Dr. Theobald, 29.
+
+  Smudges, 102.
+
+  Sore-eye, 52.
+
+  Spiders, 26.
+
+  Spiracles, 89.
+
+  Spirochæta, 21, 130.
+
+  Spore formation, 24.
+
+  Spores, 24.
+
+  Sporozoa, 22.
+
+  Spotted fever, 32.
+
+  Stable-fly, 44, 75.
+
+  Stegomyia,
+    calopus, 94, 98, 139;
+    scutellaris, 96.
+
+  Sticklebacks, 101.
+
+  Stomoxys calcitrans, 44.
+
+  Sulphur, 102.
+
+  Surra, 45.
+
+
+  Tabanus, 45.
+
+  Tahiti, mosquitoes in, 96.
+
+  Tapeworms, 2.
+
+  Tetanus, 18.
+
+  Texas fever, 28.
+
+  Theobald, Dr. F.V., 76.
+
+  Ticks, 26.
+
+  Tide-water minnows, 101.
+
+  Tobacco smoke, 102.
+
+  Top-minnows, 98, 101.
+
+  Torcel, 51.
+
+  Tracheæ, 89.
+
+  Tracheal gills, 79.
+
+  Trichina, 2.
+
+  Trypanosome, 45, 161.
+
+  Trypanosoma,
+    evansi, 45;
+    brucei, 45;
+    lewisi, 162;
+    gambiensi, 162.
+
+  Tsetse-fly, 45, 163.
+
+  Tubercular bacilli, 69;
+    germs, 69.
+
+  Typhoid-fly, 57, 59.
+
+
+  Vaughan, Dr. W.C., 67.
+
+  Ver macque, 51.
+
+  Verjbitski, D.T., 147.
+
+  Vorticella, 22.
+
+
+  Water-boatmen, 100.
+
+  Water-troughs, 104.
+
+  Whip-bearers, 20.
+
+  Whirligig beetles, 100.
+
+  White, Surgeon J.H., 134.
+
+  Wrigglers, 78.
+
+
+  Yellow fever, 120;
+    Commission, 123;
+    early observations on, 121;
+    experiments, 125;
+    danger of in Pacific Islands, 140;
+    in Havana, results of work on, 131;
+    history of in United States, 120;
+    mosquito, 94;
+    habits of, 95;
+    in Panama Canal zone, 135;
+    in Rio de Janeiro, 137;
+    summary of results of work on, 129.
+
+
+
+
+
+End of the Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
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+      The Project Gutenberg eBook of Insects and Disease, by Rennie W. Doane.
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+<pre>
+
+The Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Insects and Diseases
+       A Popular Account of the Way in Which Insects may Spread
+              or Cause some of our Common Diseases
+
+Author: Rennie W. Doane
+
+Release Date: February 24, 2009 [EBook #28177]
+Last updated: March 2, 2009
+
+Language: English
+
+Character set encoding: ISO-8859-1
+
+*** START OF THIS PROJECT GUTENBERG EBOOK INSECTS AND DISEASES ***
+
+
+
+
+Produced by Chris Curnow, Lindy Walsh, Greg Bergquist and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+</pre>
+
+
+
+<div class="tn">
+
+<p class="center"><big><b>Transcriber&#8217;s Note</b></big></p>
+
+<p class="noin">The punctuation and spelling from the original text have been faithfully preserved. Only obvious
+typographical errors have been corrected.</p>
+
+</div>
+<hr />
+
+<div class="figcenter" style="width: 600px;"><a name="Frontispiece" id="Frontispiece"></a>
+<img src="images/frontis.jpg" width="600" height="366" alt="An artificial lake, nearly dry and partly filled with
+rubbish, has become a breeding-ground for dangerous mosquitoes." title="" />
+<span class="caption">An artificial lake, nearly dry and partly filled with
+rubbish, has become a breeding-ground for dangerous mosquitoes.</span>
+</div>
+<hr />
+
+
+
+<p class="oldeng">
+American Nature Series
+</p>
+<p class="center"><big>Group IV. Working with Nature</big></p>
+<hr />
+
+<h1>INSECTS AND DISEASE</h1>
+<p class="center">
+<big>A POPULAR ACCOUNT OF THE WAY IN WHICH<br />
+INSECTS MAY SPREAD OR CAUSE SOME<br />
+OF OUR COMMON DISEASES</big><br />
+<br />
+WITH MANY ORIGINAL ILLUSTRATIONS FROM<br />
+PHOTOGRAPHS<br />
+<br />
+<br />
+BY
+<br />
+<big>RENNIE W. DOANE, A.B.</big><br />
+<br />
+<i>Assistant Professor of Entomology<br />
+Leland Stanford Junior University</i><br />
+<br />
+<br /><br /><br /><br />
+<big>LONDON</big><br />
+<br />
+<big>CONSTABLE &amp; COMPANY LIMITED</big><br />
+<br />
+<big>1910</big><br />
+</p>
+<hr />
+<p class="center"><br /><br /><br /><br />
+<span class="smcap">Copyright, 1910,</span><br />
+<br />
+BY<br />
+<br />
+HENRY HOLT AND COMPANY</p>
+<hr style="width: 10%;" />
+
+<p class="center"><i>Published August, 1910</i><br />
+<br />
+<br /><br /><br /><br />
+<small>THE QUINN &amp; BODEN CO. PRESS</small><br />
+<br />
+<small>RAHWAY, N.J.</small><br />
+</p>
+
+
+
+<hr />
+<h2><a name="PREFACE" id="PREFACE"></a>PREFACE</h2>
+
+
+<p><span class="smcap">The</span> subject of preventive medicine is one that is attracting world-wide
+attention to-day. We can hardly pick up a newspaper or magazine without
+seeing the subject discussed in some of its phases, and during the last
+few years several books have appeared devoted wholly or in part to the
+ways of preventing rather than curing many of our ills.</p>
+
+<p>Looking over the titles of these articles and books the reader will at
+once be impressed with the importance that is being given to the subject
+of the relation of insects to some of our common diseases. As many of
+these maladies are caused by minute parasites or microbes the
+zo&ouml;logists, biologists and physicians are studying with untiring zeal to
+learn what they can in regard to the development and habits of these
+organisms, and the entomologists are doing their part by studying in
+minute detail the structure and life-history of the insects that are
+concerned. Thus many important facts are being learned, many important
+observations made. The results of the best of these investigations are
+always published in technical magazines or papers that are usually
+accessible only to the specialist.</p>
+
+<p>This little book is an attempt to bring together and place in
+untechnical form the most important of these facts gathered from sources
+many of which are at present inaccessible to the general reader, perhaps
+even to many physicians and entomologists.</p>
+
+<p>In order that the reader who is not a specialist in medicine or
+entomology may more readily understand the intimate biological relations
+of the animals and parasites to be discussed it seems desirable to call
+attention first to their systematic relations and to review some of the
+important general facts in regard to their structure and life-history.
+This, it is believed, will make even the most complex special
+interrelations of some of these organisms readily understandable by all.
+Those who are already more or less familiar with these things may find
+the bibliography of use for more extended reading.</p>
+
+<p>My thanks are due to Prof. V.L. Kellogg for reading the manuscript and
+offering helpful suggestions and criticisms.</p>
+
+<p>Unless otherwise credited the pictures are from photographs taken by the
+author in the laboratory and field. As many of these are pictures of
+live specimens it is believed that they will be of interest as showing
+the insects, not as we think they should be, but as they actually are.
+Mr. J.H. Paine has given me valuable aid in preparing these photographs.</p>
+
+<p class="right">
+R.W.D.
+</p>
+
+<p class="noin">
+Stanford University, California,</p>
+<p>
+March, 1910.
+</p>
+
+
+
+<hr />
+<h2><a name="CONTENTS" id="CONTENTS"></a>CONTENTS</h2>
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="Contents">
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_I">CHAPTER I</a></td>
+</tr>
+<tr>
+ <td align='right' colspan='2'><span class="ampm"><small>PAGE</small></span></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Parasitism and Disease</span></td>
+ <td align='right'>1</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Definition of a parasite, 1; examples among various animals,
+2; <i>Parasitism</i>, 3; effect on the parasite, 4; how a harmless
+kind may become harmful, 5; immunity, 6; <i>Diseases caused by
+parasites</i>, 7; ancient and modern views, 7; <i>Infectious and contagious
+diseases</i>, 8; examples, 9; importance of distinguishing,
+9; <i>Effect of the parasite on the host</i>, 9; microbes everywhere, 10;
+importance of size, 11; numbers, 11; location, 11; mechanical
+injury, 12; morphological injury, 13; physiological effect, 13;
+the point of view, 14.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_II">CHAPTER II</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Bacteria and Protozoa</span></td>
+ <td align='right'>15</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p><i>Bacteria</i>, 15; border line between plants and animals, 15;
+most bacteria not harmful, 15; a few cause disease, 15; how
+they multiply, 15; parasitic and non-parasitic kinds, 17; how a
+kind normally harmless may become harmful, 18; effect of the
+bacteria on the host, 18; methods of dissemination, 18; <i>Protozoa</i>,
+19; <i>Am&#339;ba</i>, 19; its lack of special organs, 19; where
+it lives, 19; growth and reproduction, 19; <i>Classes of Protozoa</i>,
+20; the am&#339;ba-like forms, 20; the flagellate forms, 20; importance
+of these, 21; the ciliated forms, 22; the Sporozoa or
+spore-forming kinds, 22; these most important, 23; abundance,
+23; adaptability, 23; common characters, 24; ability to
+resist unfavorable conditions, 24.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_III">CHAPTER III</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Ticks and Mites</span></td>
+ <td align='right'>26</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p><i>Ticks</i>, 26; general characters, 27; mouth-parts, 27; habits,
+27; life-history, 27; <i>Ticks and disease</i>, 28; <i>Texas fever</i>, 28; its
+occurrence in the north, 28; carried by a tick, 29; loss and
+methods of control, 31; other diseases of cattle carried by ticks,
+31; <i>Rocky Mountain spotted fever</i>, 32; its occurrence, 32;
+probably caused by parasites, 32; relation of ticks to this disease,
+33; <i>Relapsing Fever</i>, 33; its occurrence, 34; transmitted
+by ticks, 34; <i>Mites</i>, 35; <i>Face-mites</i>, 35; <i>Itch-mites</i>, 36; <i>Harvest-mites</i>, 37.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_IV">CHAPTER IV</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">How Insects Cause or Carry Disease</span></td>
+ <td align='right'>40</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Numbers, 40; importance, 41; losses caused by insects, 41;
+loss of life, 42; <i>The flies</i>, 43; horse-flies, 43; stable-flies, 44;
+surra, 45; nagana, 45; black-flies, 46; punkies, 46; screw-worm
+flies, 47; blow-flies, 48; flesh-flies, 48; fly larv&aelig; in intestinal
+canal, 49; bot-flies, 50; <i>Fleas</i>, 52; jigger-flea, 53; <i>Bedbugs</i>, 54;
+<i>Lice</i>, 54; <i>How insects may carry disease</i>, 55; in a mechanical
+way, 55; as one of the necessary hosts of the parasite, 56.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_V">CHAPTER V</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">House-flies or Typhoid-flies</span></td>
+ <td align='right'>57</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>The old attitude toward the house-fly, 57; its present standing,
+58; reasons for the change, 58; <i>Structure</i>, 59; head and
+mouth-parts, 60; thorax and wings, 61; feet, 62; <i>How they
+carry bacteria</i>, 62; <i>Life-history</i>, 63; eggs, 63; ordinarily laid in
+manure, 63; other places, 63; habits of the larv&aelig;, 64; habits of
+the adults, 64; places they visit, 65; <i>Flies and typhoid</i>, 65;
+patients carrying the germs before and after they have had the
+disease, 65; how the flies get these on their body and distribute
+them, 66; results of some observations and experiments, 66;
+<i>Flies and other diseases</i>, 68; flies and cholera, 68; flies and tuberculosis,
+69; possibility of their carrying other diseases, 70;
+<i>Fighting flies</i>, 71; screens not sufficient, 71; the larger problem,
+71; the manure pile, 72; outdoor privies, 72; garbage can,
+72; co&ouml;peration necessary, 72; city ordinances, 73; an expert's
+opinion of the house-fly, 73; <i>Other flies</i>, 75; habits of several
+much the same but do not enter house as much, 75; the small
+house-fly, 75; stable-flies, 75; these may spread disease, 75.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_VI">CHAPTER VI</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Mosquitoes</span></td>
+ <td align='right'>76</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Numbers, 76; interest and importance, 76; eggs, 77; always
+in water, 77; time of hatching, 77; <i>Larv&aelig;</i>, 78; live only in water,
+78; head and mouth-parts of larv&aelig;, 78; what they feed on,
+78; breathing apparatus, 79; growth of the larv&aelig;, 80; <i>Pup&aelig;</i>,
+80; active but takes no food, 80; breathing tubes, 80; how the
+adult issues, 81; <i>The Adult</i>, 81; male and female, 81; how mosquitoes
+"sing" and how the song is heard, 82; the palpi, 82;
+<i>The Mouth-parts</i>, 83; needles for piercing, 83; <i>How the mosquito
+bites</i>, 84; secretion from the salivary gland, 84; why males
+cannot bite, 84; blood not necessary for either sex, 84; <i>The
+Thorax</i>, 85; the legs, 85; the wings, 85; the balancers, 85; the
+breathing pores, 86; <i>The abdomen</i>, 86; <i>The digestive system</i>,
+86; <i>The salivary glands</i>, 87; their importance, 87; effects of a
+mosquito bite, 87; probable function of the saliva, 88; <i>How
+mosquitoes breathe</i>, 89; <i>Blood</i>, 90; in body cavity, 90; heart, 90;
+<i>Classification</i>, 91; <i>Anopheles</i>, 91; distinguishing characters, 92;
+eggs, 92; where the larv&aelig; are found, 93; <i>Yellow fever mosquito</i>,
+94; its importance, 94; the adult, 95; habits, 95; habits of the
+larv&aelig;, 95; <i>Other species</i>, 96; some in fresh water, others in
+brackish water, 96; Natural enemies of mosquitoes, 97; how
+natural enemies of mosquitoes control their numbers, 98; mosquitoes
+in Hawaii, 98; <i>Enemies of the adults</i>, 99; <i>Enemies of
+the larv&aelig; and pup&aelig;</i>, 100; <i>Fighting mosquitoes</i>, 101; fighting
+the adult, 102; <i>Fighting the larv&aelig;</i>, 103; domestic or local
+species, 104; draining and treating with oil, 104; combatting
+salt-marsh species by draining, 105; by minnows or oil, 105.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_VII">CHAPTER VII</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Mosquitoes and Malaria</span></td>
+ <td align='right'>106</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Early reference to malaria, 106; its general distribution, 106;
+theories in regard to its cause, 107; insects early suspected, 107;
+<i>The parasite that causes malaria</i>, 108; studies of the parasite,
+108; <i>Life-history in human host</i>, 109; its effect on the host, 110;
+the search for the sexual generation, 111; <i>The parasite in the
+mosquito</i>, 112; review of whole life-history, 115; malaria transmitted
+only by mosquitoes, 115; <i>Summary</i>, 117; experimental
+proof, 118.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_VIII">CHAPTER VIII</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Mosquitoes and Yellow Fever</span></td>
+ <td align='right'>120</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>A disease of tropical or semi-tropical countries, 120; outbreaks
+in the United States, 120; parasite that causes the disease
+not known, 121; formerly regarded as a contagious disease,
+122; <i>The yellow fever commission</i>, 123; Dr. Finlay's
+claim, 124; experiments made by the commission, 125; summary
+of results, 129; what it means, 130; <i>results in Havana</i>,
+131; <i>the fight in New Orleans</i>, 132; <i>In the Panama canal zone</i>,
+135; <i>in Rio de Janeiro</i>, 136; claims of the French commission,
+138; <i>habits of stegomyia</i>, 139; breeding habits, 139; possible
+results of war against the mosquitoes, 139; Danger of this disease
+in the Pacific Islands, 140.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_IX">CHAPTER IX</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Fleas and Plague</span></td>
+ <td align='right'>142</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Great scourges, 142; the "black death," 142; old conditions
+and new, 143; <i>How plague was controlled in San Francisco</i>,
+143; <i>Indian Plague commission</i>, 144; Dr. Simond's claim,
+145; The advisory committee and the new commission, 146;
+<i>Results of Dr. Verjbitski's experiments</i>, 147; <i>Results of various
+investigations</i>, 150; <i>structure and habits of fleas</i>, 151; feeding
+habits, 152; <i>Common species of fleas</i>, 153; <i>Ground squirrels and
+plague</i>, 155; squirrel fleas, 156; <i>Remedies for fleas</i>, 157; cats
+and dogs, 159.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='center'><a href="#CHAPTER_X">CHAPTER X</a></td>
+</tr>
+<tr>
+ <td align='left'><span class="smcap">Other Diseases, Mostly Tropical, Known or Thought to
+Be Transmitted by Insects</span></td>
+ <td align='right'>161</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p><i>Sleeping Sickness</i>, 161; its occurrence in Africa, 161; caused
+by a Protozoan parasite, 162; the tsetse-fly, 163; <i>Elephantiasis</i>,
+164; caused by parasitic worms, 164; their development,
+165; how they are transferred to man, 165; effect on the patient,
+166; <i>Dengue</i>, 168; other names, 168; probably transmitted
+by mosquitoes, 170; <i>Mediterranean fever</i>, 171; cause,
+171; may be conveyed by mosquitoes, 171; <i>Leprosy</i>, 171;
+caused by a bacteria parasite, 171; possibilities of flies, mosquitoes
+and other insects transmitting the disease, 172; <i>Kala-azar</i>,
+173; transmitted by the bedbug, 173; <i>Oriental sore</i>, 174;
+the parasite may be carried by insects, 174.</p></td>
+</tr>
+<tr class='tr1'>
+ <td align='left'><span class="smcap"><a href="#BIBLIOGRAPHY">Bibliography</a></span></td>
+ <td align='right'>175</td>
+</tr>
+<tr>
+ <td class='tdlpl1'><p>Parasites and parasitism, 175; Protozoa, 176; Bacteria, 177;
+Insects and disease, 178; Mosquitoes&mdash;systematic and general,
+179; Mosquito anatomy, 182; Mosquitoes&mdash;life-history and
+habits, 183; Mosquito fighting, 183; Mosquitoes and disease,
+185; Malaria, 186; Yellow fever, 189; Dengue, 192; Filarial
+diseases and elephantiasis, 193; Leprosy, 193; Plague, 194;
+Fleas, 198; Typhoid fever, 199; House-flies&mdash;anatomy, life-history,
+habits, 200; House-flies and typhoid, 202; House-fly
+and various diseases, 203; Human myiasis, 207; Stomoxys
+and other flies, 208; tsetse-flies, 209; Trypanosomes and Trypanosomiasis,
+210; Sleeping sickness, 211; Rocky mountain
+fever and ticks, 212; Ticks and various diseases, 213; Kala-azar
+and bedbugs, 216; Text or reference books, 216; Miscellaneous
+articles, 218.</p></td>
+</tr>
+</table></div>
+
+
+
+
+<hr />
+<h2><a name="ILLUSTRATIONS" id="ILLUSTRATIONS"></a>ILLUSTRATIONS</h2>
+
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="Illustrations">
+<tr class='tr2'>
+ <td align='right'>&nbsp;</td>
+ <td align='left'><span class="smcap">An artificial lake, nearly dry and partly<br />
+filled with rubbish, has become a breeding-ground<br />
+for dangerous mosquitoes</span></td>
+ <td align='right'><i><a href="#Frontispiece">Frontispiece</a></i></td>
+</tr>
+<tr>
+ <td align='right'>&nbsp;</td>
+ <td align='left'>&nbsp;</td>
+ <td align='right'><span class="ampm">PAGE</span></td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_1">Fig. 1.</a></span></td>
+ <td align='left'><span class="smcap">A lamprey</span></td>
+ <td align='right'>2</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_2">Fig. 2.</a></span></td>
+ <td align='left'><i>Sacculina</i></td>
+ <td align='right'>2</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_3">Fig. 3.</a></span></td>
+ <td align='left'><i>Trichina spiralis</i></td>
+ <td align='right'>2</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_4">Fig. 4.</a></span></td>
+ <td align='left'><span class="smcap">An external parasite, a bird-louse</span> (<i>Lipeurus ferox</i>)</td>
+ <td align='right'>3</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_5">Fig. 5.</a></span></td>
+ <td align='left'><span class="smcap">An internal parasite, a tachina fly</span> (<i>Blepharipeza adusta</i>)</td>
+ <td align='right'>3</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_6">Fig. 6.</a></span></td>
+ <td align='left'><span class="smcap">Work of an internal parasite, puss-moth larva parasitized by a small ichneumon fly</span></td>
+ <td align='right'>3</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_7">Fig. 7.</a></span></td>
+ <td align='left'><span class="smcap">Typhoid fever bacilli</span></td>
+ <td align='right'>20</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_8">Fig. 8.</a></span></td>
+ <td align='left'><i>Am&#339;ba</i></td>
+ <td align='right'>20</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_9">Fig. 9.</a></span></td>
+ <td align='left'><i>Euglina virdis</i></td>
+ <td align='right'>21</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_10">Fig. 10.</a></span></td>
+ <td align='left'><i>Spirocheta duttoni</i></td>
+ <td align='right'>21</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_11">Fig. 11.</a></span></td>
+ <td align='left'><i>Param&#339;cium</i></td>
+ <td align='right'>22</td></tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_12">Fig. 12.</a></span></td>
+ <td align='left'><i>Vorticella</i></td>
+ <td align='right'>22</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_13">Fig. 13.</a></span></td>
+ <td align='left'><span class="smcap">Pathogenic protozoa; a group of intestinal parasites</span></td>
+ <td align='right'>22</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_14">Fig. 14.</a></span></td>
+ <td align='left'><span class="smcap">Castor-bean tick</span> (<i>Ixodes ricinus</i>)</td>
+ <td align='right'>28</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_15">Fig. 15.</a></span></td>
+ <td align='left'><span class="smcap">Texas fever tick</span></td>
+ <td align='right'>28</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_16">Fig. 16.</a></span></td>
+ <td align='left'><span class="smcap">Texas fever tick</span> (<i>Margaropus annulatus</i>)</td>
+ <td align='right'>29</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_17">Fig. 17.</a></span></td>
+ <td align='left'><i>Amblyomma variegatum</i></td>
+ <td align='right'>29</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_18">Fig. 18.</a></span></td>
+ <td align='left'><i>Ornithodoros moubata</i></td>
+ <td align='right'>36</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_19">Fig. 19.</a></span></td>
+ <td align='left'><span class="smcap">The follicle mite</span> (<i>Demodex folliculorum</i>)</td>
+ <td align='right'>36</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_20">Fig. 20.</a></span></td>
+ <td align='left'><span class="smcap">Itch-mite</span> (<i>Sarcoptes scabiei</i>)</td>
+ <td align='right'>37</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_21">Fig. 21.</a></span></td>
+ <td align='left'><span class="smcap">Harvest-mites or "jiggers"</span></td>
+ <td align='right'>37</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_22">Fig. 22.</a></span></td>
+ <td align='left'><span class="smcap">Horse-fly</span> (<i>Tabanus punctifer</i>)</td>
+ <td align='right'>44</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_23">Fig. 23.</a></span></td>
+ <td align='left'><span class="smcap">Stable-fly</span> (<i>Stomoxys calcitrans</i>)</td>
+ <td align='right'>44</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_24">Fig. 24.</a></span></td>
+ <td align='left'><span class="smcap">A black-fly</span> (<i>Simulium sp.</i>)</td>
+ <td align='right'>45</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_25">Fig. 25.</a></span></td>
+ <td align='left'><span class="smcap">Screw-worm fly</span> (<i>Chrysomyia macellaria</i>)</td>
+ <td align='right'>45</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_26">Fig. 26.</a></span></td>
+ <td align='left'><span class="smcap">Blow-fly</span> (<i>Calliphora vomitoria</i>)</td>
+ <td align='right'>45</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_27">Fig. 27.</a></span></td>
+ <td align='left'><span class="smcap">Blue-bottle fly</span> (<i>Lucilia sericata</i>)</td>
+ <td align='right'>50</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_28">Fig. 28.</a></span></td>
+ <td align='left'><span class="smcap">Flesh-fly</span> (<i>Sarcophaga sp.</i>)</td>
+ <td align='right'>50</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_29">Fig. 29.</a></span></td>
+ <td align='left'><span class="smcap">"The little house-fly</span>" (<i>Homalomyia canicularis</i>)</td>
+ <td align='right'>51</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_30">Fig. 30.</a></span></td>
+ <td align='left'><span class="smcap">Horse bot-fly</span> (<i>Gastrophilus equi.</i>)</td>
+ <td align='right'>51</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_31">Fig. 31.</a></span></td>
+ <td align='left'><span class="smcap">Oxwarble fly</span> (<i>Hypoderma lineata</i>)</td>
+ <td align='right'>51</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_32">Fig. 32.</a></span></td>
+ <td align='left'><span class="smcap">Sheep bot-fly</span> (<i>Gastrophilus nasalis</i>)</td>
+ <td align='right'>51</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_33">Fig. 33.</a></span></td>
+ <td align='left'><span class="smcap">Chigo or jigger-flea, male</span> (<i>Dermatophilus penetrans</i>)</td>
+ <td align='right'>54</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_34">Fig. 34.</a></span></td>
+ <td align='left'><span class="smcap">Chigo, female distended with eggs</span></td>
+ <td align='right'>54</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_35">Fig. 35.</a></span></td>
+ <td align='left'><span class="smcap">Bedbug</span> (<i>Cimex lectularis</i>)</td>
+ <td align='right'>55</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_36">Fig. 36.</a></span></td>
+ <td align='left'><span class="smcap">Body-louse</span> (<i>Pediculus vestimenti</i>)</td>
+ <td align='right'>55</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_37">Fig. 37.</a></span></td>
+ <td align='left'><span class="smcap">One use for the house-fly</span></td>
+ <td align='right'>57</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_38">Fig. 38.</a></span></td>
+ <td align='left'><span class="smcap">The house-fly</span> (<i>Musca domestica</i>)</td>
+ <td align='right'>58</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_39">Fig. 39.</a></span></td>
+ <td align='left'><span class="smcap">Head of house-fly showing eyes, antenn&aelig; and mouth-parts</span></td>
+ <td align='right'>60</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_40">Fig. 40.</a></span></td>
+ <td align='left'><span class="smcap">Proboscis of house-fly, side view</span></td>
+ <td align='right'>60</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_41">Fig. 41.</a></span></td>
+ <td align='left'><span class="smcap">Lobes at end of proboscis of house-fly showing corrugated ridges</span></td>
+ <td align='right'>61</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_42">Fig. 42.</a></span></td>
+ <td align='left'><span class="smcap">Wing of house-fly</span></td>
+ <td align='right'>61</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_43">Fig. 43.</a></span></td>
+ <td align='left'><span class="smcap">Wing of stable-fly</span> (<i>Stomoxys calcitrans</i>)</td>
+ <td align='right'>62</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_44">Fig. 44.</a></span></td>
+ <td align='left'><span class="smcap">Wing of house-fly showing particles of dirt adhering to it</span></td>
+ <td align='right'>62</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_45">Fig. 45.</a></span></td>
+ <td align='left'><span class="smcap">Last three segments of leg of house-fly</span></td>
+ <td align='right'>62</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_46">Fig. 46.</a></span></td>
+ <td align='left'><span class="smcap">Foot of house-fly</span></td>
+ <td align='right'>63</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_47">Fig. 47.</a></span></td>
+ <td align='left'><span class="smcap">Larva of house-fly</span></td>
+ <td align='right'>63</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_48">Fig. 48.</a></span></td>
+ <td align='left'><span class="smcap">Barn-yard filled with manure</span></td>
+ <td align='right'>64</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_49">Fig. 49.</a></span></td>
+ <td align='left'><span class="smcap">Dirty stalls</span></td>
+ <td align='right'>65</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_50">Fig. 50.</a></span></td>
+ <td align='left'><span class="smcap">Pupa of house-fly</span></td>
+ <td align='right'>76</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_51">Fig. 51.</a></span></td>
+ <td align='left'><span class="smcap">Head of stable-fly</span></td>
+ <td align='right'>76</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_52">Fig. 52.</a></span></td>
+ <td align='left'><span class="smcap">Mass of mosquito eggs</span> (<i>Theobaldia incidens</i>)</td>
+ <td align='right'>76</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_53">Fig. 53.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito eggs and larv&aelig;</span> (<i>T. incidens</i>)</td>
+ <td align='right'>77</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_54">Fig. 54.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito larva</span> (<i>T. incidens</i>), <span class="ampm">DORSAL VIEW</span></td>
+ <td align='right'>77</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_55">Fig. 55.</a></span></td>
+ <td align='left'><span class="smcap">Eggs, larv&aelig; and pup&aelig; of mosquitoes</span> (<i>T. incidens</i>)</td>
+ <td align='right'>78</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_56">Fig. 56.</a></span></td>
+ <td align='left'><span class="smcap">Larva of mosquito</span> (<i>T. incidens</i>)</td>
+ <td align='right'>78</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_57">Fig. 57.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito larv&aelig; and pup&aelig;</span> (<i>T. incidens</i>)</td>
+ <td align='right'>79</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_58">Fig. 58.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles larv&aelig;</span> (<i>A. maculipennis</i>)</td>
+ <td align='right'>79</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_59">Fig. 59.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito pup&aelig;</span> (<i>T. incidens</i>)</td>
+ <td align='right'>80</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_60">Fig. 60.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito pupa</span> (<i>T. incidens</i>)</td>
+ <td align='right'>80</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_61">Fig. 61.</a></span></td>
+ <td align='left'><span class="smcap">Mosquito larv&aelig; and pup&aelig;</span> (<i>T. incidens</i>)</td>
+ <td align='right'>80</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_62">Fig. 62.</a></span></td>
+ <td align='left'><span class="smcap">A female mosquito</span> (<i>T. incidens</i>)</td>
+ <td align='right'>81</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_63">Fig. 63.</a></span></td>
+ <td align='left'><span class="smcap">A male mosquito</span> (<i>T. incidens</i>)</td>
+ <td align='right'>81</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_64">Fig. 64.</a></span></td>
+ <td align='left'><span class="smcap">Head and thorax of female mosquito</span> (<i>Ochlerotatus lativittatus</i>)</td>
+ <td align='right'>82</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_65">Fig. 65.</a></span></td>
+ <td align='left'><span class="smcap">Head and thorax of male mosquito</span> (<i>O. lativittatus</i>)</td>
+ <td align='right'>82</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_66">Fig. 66.</a></span></td>
+ <td align='left'><span class="smcap">Head of female mosquito</span></td>
+ <td align='right'>83</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_67">Fig. 67.</a></span></td>
+ <td align='left'><span class="smcap">Cross-section of proboscis of female and male mosquito</span></td>
+ <td align='right'>83</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_68">Fig. 68.</a></span></td>
+ <td align='left'><span class="smcap">Wing of mosquito</span> (<i>O. lativittatus</i>)</td>
+ <td align='right'>86</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_69">Fig. 69.</a></span></td>
+ <td align='left'><span class="smcap">End of mosquito wing highly magnified</span></td>
+ <td align='right'>86</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_70">Fig. 70.</a></span></td>
+ <td align='left'><span class="smcap">Diagram to show the alimentary canal and salivary glands of a mosquito</span></td>
+ <td align='right'>87</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_71">Fig. 71.</a></span></td>
+ <td align='left'><span class="smcap">Salivary glands of mosquitoes</span></td>
+ <td align='right'>87</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_72">Fig. 72.</a></span></td>
+ <td align='left'><span class="smcap">Heads of culicin&aelig; mosquitoes</span></td>
+ <td align='right'>90</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_73">Fig. 73.</a></span></td>
+ <td align='left'><span class="smcap">Heads of anophelin&aelig; mosquitoes</span></td>
+ <td align='right'>90</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_74">Fig. 74.</a></span></td>
+ <td align='left'><span class="smcap">Wing of</span> <i>Anopheles maculipennis</i></td>
+ <td align='right'>90</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_75">Fig. 75.</a></span></td>
+ <td align='left'><span class="smcap">Wing of</span> <i>Theobaldia incidens</i></td>
+ <td align='right'>90</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_76">Fig. 76.</a></span></td>
+ <td align='left'><span class="smcap">A non-malarial mosquito</span> (<i>T. Incidens</i>), <span class="ampm">MALE, STANDING ON THE WALL</span></td>
+ <td align='right'>91</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_77">Fig. 77.</a></span></td>
+ <td align='left'><span class="smcap">Female of same</span>
+ </td><td align='right'>91</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_78">Fig. 78.</a></span></td>
+ <td align='left'><span class="smcap">A malarial mosquito</span> (<i>A. maculipennis</i>), <span class="ampm">MALE, STANDING ON THE WALL</span></td>
+ <td align='right'>91</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_79">Fig. 79.</a></span></td>
+ <td align='left'><span class="smcap">Female of same</span></td>
+ <td align='right'>91</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_80">Fig. 80.</a></span></td>
+ <td align='left'><span class="smcap">Egg of</span> <i>Anopheles</i>, <span class="ampm">SIDE VIEW</span></td>
+ <td align='right'>92</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_81">Fig. 81.</a></span></td>
+ <td align='left'><span class="smcap">Egg of anopheles, dorsal view</span></td>
+ <td align='right'>92</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_82">Fig. 82.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles larv&aelig;</span></td>
+ <td align='right'>92</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_83">Fig. 83.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles larv&aelig;</span></td>
+ <td align='right'>93</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_84">Fig. 84.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles larva, dorsal view</span></td>
+ <td align='right'>93</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_85">Fig. 85.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles pup&aelig; resting at surface of water</span></td>
+ <td align='right'>93</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_86">Fig. 86.</a></span></td>
+ <td align='left'><span class="smcap">Salt-marsh mosquito</span> (<i>Ochlerotatus lativittatus</i>); <span class="ampm">MALE</span></td>
+ <td align='right'>98</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_87">Fig. 87.</a></span></td>
+ <td align='left'><span class="smcap">Salt-marsh mosquito</span> (<i>O. lativittatus</i>); <span class="ampm">FEMALE</span></td>
+ <td align='right'>98</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_88">Fig. 88.</a></span></td>
+ <td align='left'><span class="smcap">Top-minnow</span> (<i>Mollienisia latipinna</i>)</td>
+ <td align='right'>99</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_89">Fig. 89.</a></span></td>
+ <td align='left'><span class="smcap">Dragon-flies</span></td>
+ <td align='right'>99</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_90">Fig. 90.</a></span></td>
+ <td align='left'><span class="smcap">The Young (nymph) of a dragon-fly</span></td>
+ <td align='right'>100</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_91">Fig. 91.</a></span></td>
+ <td align='left'><span class="smcap">The cast skin</span> (<i>exuv&aelig;</i>) <span class="smcap">of a dragon-fly nymph</span></td>
+ <td align='right'>100</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_92">Fig. 92.</a></span></td>
+ <td align='left'><span class="smcap">Diving-beetles and back-swimmers</span></td>
+ <td align='right'>101</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_93">Fig. 93.</a></span></td>
+ <td align='left'><span class="smcap">Killifish</span> (<i>Fundulus heteroliatus</i>)</td>
+ <td align='right'>102</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_94">Fig. 94.</a></span></td>
+ <td align='left'><span class="smcap">Stickleback</span> (<i>Apeltes quadracus</i>)</td>
+ <td align='right'>102</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_95">Fig. 95.</a></span></td>
+ <td align='left'><span class="smcap">An old watering-trough, an excellent breeding-place for mosquitoes</span></td>
+ <td align='right'>103</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_96">Fig. 96.</a></span></td>
+ <td align='left'><span class="smcap">Horse and cattle tracks in mud filled with water</span></td>
+ <td align='right'>108</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_97">Fig. 97.</a></span></td>
+ <td align='left'><span class="smcap">A malarial mosquito</span> (<i>Anopheles maculipennis</i>)<span class="ampm">MALE</span></td>
+ <td align='right'>108</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_98">Fig. 98.</a></span></td>
+ <td align='left'><span class="smcap">A malarial mosquito</span> (<i>A. maculipennis</i>) <span class="ampm">FEMALE</span></td>
+ <td align='right'>109</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_99">Fig. 99.</a></span></td>
+ <td align='left'><span class="smcap">Diagram to illustrate the life-history of the malarial parasite</span></td>
+ <td align='right'>110</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_100">Fig. 100.</a></span></td>
+ <td align='left'><span class="smcap">Malarial mosquito</span> (<i>A. maculipennis</i>) <span class="ampm">ON THE WALL</span></td>
+ <td align='right'>111</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_101">Fig. 101.</a></span></td>
+ <td align='left'><span class="smcap">Malarial mosquito</span> (<i>A. maculipennis</i>) <span class="ampm">STANDING ON A TABLE</span></td>
+ <td align='right'>111</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_102">Fig. 102.</a></span></td>
+ <td align='left'><span class="smcap">Salt-marsh mosquito</span> (<i>O. lativittatus</i>) <span class="ampm">STANDING ON A TABLE</span></td>
+ <td align='right'>118</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_103">Fig. 103.</a></span></td>
+ <td align='left'><span class="smcap">Anopheles hanging from the ceiling</span></td>
+ <td align='right'>118</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_104">Fig. 104.</a></span></td>
+ <td align='left'><span class="smcap">Yellow fever mosquito</span> (<i>Stegomyia calopus</i>)</td>
+ <td align='right'>122</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_105">Fig. 105.</a></span></td>
+ <td align='left'><span class="smcap">Rat-flea</span> (<i>L&aelig;mopsylla cheopis</i>); <span class="ampm">MALE</span></td>
+ <td align='right'>152</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_106">Fig. 106.</a></span></td>
+ <td align='left'><span class="smcap">Rat-flea</span> (<i>L. cheopis</i>); <span class="ampm">FEMALE</span></td>
+ <td align='right'>152</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_107">Fig. 107.</a></span></td>
+ <td align='left'><span class="smcap">Head of rat-flea showing mouth-parts</span></td>
+ <td align='right'>153</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_108">Fig. 108.</a></span></td>
+ <td align='left'><span class="smcap">Human-flea</span> (<i>Pulex irritans</i>); <span class="ampm">MALE</span></td>
+ <td align='right'>153</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_109">Fig. 109.</a></span></td>
+ <td align='left'><span class="smcap">Human-flea</span> (<i>P. irritans</i>); <span class="ampm">FEMALE</span></td>
+ <td align='right'>156</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_110">Fig. 110.</a></span></td>
+ <td align='left'><span class="smcap">Mouse-flea</span> (<i>Ctenopsyllus musculi</i>); <span class="ampm">FEMALE</span></td>
+ <td align='right'>156</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_111">Fig. 111.</a></span></td>
+ <td align='left'><span class="smcap">Trypanosoma gambiense</span></td>
+ <td align='right'>164</td>
+</tr>
+<tr>
+ <td align='right'><span class="smcap"><a href="#Fig_112">Fig. 112.</a></span></td>
+ <td align='left'><span class="smcap">Tsetse-fly</span></td>
+ <td align='right'>164</td>
+</tr>
+</table></div>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_1" id="Page_1">[Pg 1]</a></span></p>
+<h2><a name="INSECTS_AND_DISEASE" id="INSECTS_AND_DISEASE"></a>INSECTS AND DISEASE</h2>
+
+
+
+<hr />
+<h2><a name="CHAPTER_I" id="CHAPTER_I"></a>CHAPTER I</h2>
+
+<h3>PARASITISM AND DISEASE</h3>
+
+
+<p class="center">PARASITES</p>
+
+<div class="figdrop">
+<img src="images/dropt.jpg" width="75" height="77" alt="dropt" title="" />
+</div>
+<p class="noin"><span class="caps">he</span> dictionary says that a parasite is a living organism, either animal
+or plant, that lives in or on some other organism from which it derives
+its nourishment for a whole or part of its existence. This definition
+will serve as well as any, as it seems to include all the forms that
+might be classed as parasites. As a general thing, however, we are
+accustomed to think of a parasite as working more or less injury to its
+host, or perhaps we had better say that if it does not cause any
+irritation or ill effects its presence is not noted and we do not think
+of it at all.</p>
+
+<p>As a matter of fact the number of parasitic organisms that are actually
+detrimental to the welfare of their hosts is comparatively small while
+the number of forms both large and small that lead<span class='pagenum'><a name="Page_2" id="Page_2">[Pg 2]</a></span> parasitic lives in
+or on various hosts, usually doing no appreciable harm, often perhaps
+without the host being aware of their presence, is very great indeed.</p>
+
+<p>Few of the higher animals live parasitic lives. The nearest approach to
+a true parasite among the vertebrates is the lamprey-eel (<a href="#Fig_1">Fig. 1</a>) which
+attaches itself to the body of a fish and sucks the blood or eats the
+flesh. Among the Crustaceans, the group that includes the lobsters and
+crabs, we find many examples of parasites, the most extraordinary of
+which is the curious crab known as <i>Sacculina</i> (<a href="#Fig_2">Fig. 2</a>). In its early
+stages this creature is free-swimming and looks not unlike other young
+crabs. But it soon attaches itself to another crab and begins to live at
+the expense of its host. Then it commences to undergo remarkable changes
+and finally becomes a mere sac-like organ with a number of long slender
+root-like processes penetrating and taking nourishment from the body of
+the unfortunate crab-host.</p>
+
+<p>The worms furnish many well-known examples of parasites, whole groups of
+them being especially adapted to parasitic life. The tapeworms, common
+in many animals and often occurring in man, the roundworms of which the
+trichina (<a href="#Fig_3">Fig. 3</a>) that causes "measly" pork is a representative, are
+familiar examples. These and a host of others all show a very high
+degree of specialization fitting them for their peculiar lives in their
+hosts.</p>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 1, 2 and 3">
+<tr>
+ <td class="tdf" colspan='2'><a name="Fig_1" id="Fig_1"></a><img src="images/fig1.jpg" width="450" height="144" alt="Fig. 1" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 1</span></span></td>
+</tr>
+<tr>
+ <td class="tdf"><a name="Fig_2" id="Fig_2"></a><img src="images/fig2.jpg" width="300" height="473" alt="Fig. 2" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 2</span></span></td>
+ <td class="tdf"><a name="Fig_3" id="Fig_3"></a><img src="images/fig3.jpg" width="200" height="410" alt="Fig. 3" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 3</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 1</span>&mdash;A lamprey. (After Goode.)</p>
+<p class="caption2"><span class="smcap">Fig. 2</span>&mdash;<i>Sacculina; A</i>, parasite attached to a crab;
+<i>B</i>, the active larval condition; <i>C</i>, the adult removed from its host.
+(After Haeckel.)</p>
+<p class="caption2"><span class="smcap">Fig. 3</span>&mdash;<i>Trichina spiralis</i> encysted in muscle of a pig.
+(From Kellogg&#39;s Elementary Zo&ouml;l.)</p></td>
+</tr>
+</table>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 4, 5 and 6">
+<tr>
+ <td class="tdf"><a name="Fig_4" id="Fig_4"></a><img src="images/fig4.jpg" width="250" height="396" alt="Fig. 4" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 4</span></span></td>
+ <td class="tdf"><a name="Fig_5" id="Fig_5"></a><img src="images/fig5.jpg" width="250" height="340" alt="Fig. 5" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 5</span></span></td>
+</tr>
+<tr>
+ <td class="tdf" colspan='2'><a name="Fig_6" id="Fig_6"></a><img src="images/fig6.jpg" width="350" height="253" alt="Fig. 6" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 6</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 4</span>&mdash;An external parasite, a bird-louse (<i>Lipeurus
+ferox</i>).</p>
+<p class="caption2"><span class="smcap">Fig. 5</span>&mdash;A tachina fly (<i>Blepharipeza adusta</i>) the larva
+of which is an internal parasite.</p>
+<p class="caption2"><span class="smcap">Fig. 6</span>&mdash;Work of an internal parasite, puss-moth larva
+parasitized by a small ichneumon fly.</p></td>
+</tr>
+</table>
+
+<p><span class='pagenum'><a name="Page_3" id="Page_3">[Pg 3]</a></span></p><p>From among the insects may be selected interesting examples of almost
+all kinds and degrees of parasitism, temporary, permanent, external,
+internal (<a href="#Fig_4">Figs. 4</a>, <a href="#Fig_5">5</a>, <a href="#Fig_6">6</a>). Among them is found, too, that curious
+condition known as hyperparasitism where one animal, itself a parasite,
+is preyed upon by a still smaller parasite.</p>
+
+<p class="poem">
+"The larger fleas have smaller fleas<br />
+Upon their backs to bite um,<br />
+These little fleas still smaller fleas<br />
+And so <i>ad infinitum</i>."<br />
+</p>
+
+<p>Coming now to the minute, microscopic, one-celled animals, the Protozoa,
+we find entire groups of them that are living parasitic lives, depending
+wholly on one or more hosts for their existence. Many of these have a
+very remarkable life-history, living part of the time in one host, part
+in another. The malarial parasite and others that cause some of the
+diseases of man and domestic animals are among the most important of
+these.</p>
+
+
+<p class="center">PARASITISM</p>
+
+<p>Among all these parasites, from the highest to the lowest the process
+that has fitted them for a<span class='pagenum'><a name="Page_4" id="Page_4">[Pg 4]</a></span> parasitic life has been one of degeneration.
+While they may be specialized to an extreme degree in one direction they
+are usually found to have some of the parts or organs, which in closely
+related forms are well developed, atrophied or entirely wanting. As a
+rule this is a distinct advantage rather than a disadvantage to the
+parasite, for those parts or organs that are lost would be useless or
+even in the way in its special mode of life.</p>
+
+<p>Then, too, the parasite often gives up all its independence and becomes
+wholly dependent on its host or hosts not only for its food but for its
+dissemination from one animal to another, in order that the species may
+not perish with the host. But in return for all this it has gained a
+life of ease, free from most of the dangers that beset the more
+independent animals, and is thus able to devote its whole time and
+energy to development and the propagation of the species.</p>
+
+<p>We are accustomed to group the parasites that we know into two classes,
+as harmful or injurious and as harmless, the latter including all those
+kinds that do not ordinarily affect our well-being in any way. But such
+a classification is not always satisfactory or safe, for certain
+organisms that to-day or under present conditions are not harmful may,
+on account of a great increase in numbers or<span class='pagenum'><a name="Page_5" id="Page_5">[Pg 5]</a></span> change of conditions,
+become of prime importance to-morrow. An animal that is well and strong
+may harbor large numbers of parasites which are living at the expense of
+some of the host's food or energy or comfort, yet the loss is so small
+that it is not noticed and the intruders, if they are thought of at all,
+are classed as harmless. Or we may at times even look upon them as
+beneficial in one way or another. "A reasonable amount of fleas is good
+for a dog. They keep him from brooding on being a dog."</p>
+
+<p>But should these parasites for some reason or other increase rapidly
+they might work great harm to the host. Even David Harum would limit the
+number of fleas on a dog. Or the animal might become weakened from some
+cause so that the drain on its resources made by the parasites, even
+though they did not increase in numbers, would materially affect it.</p>
+
+<p>Perhaps the most serious way in which parasites that are usually
+harmless may become of great importance is illustrated by their
+introduction into new regions or, as is more often the case, by the
+introduction of new hosts into the region where the parasites are found.
+Under normal conditions the animals of a given region are usually immune
+to the parasites of the same region. That<span class='pagenum'><a name="Page_6" id="Page_6">[Pg 6]</a></span> is, they actually repel them
+and do not suffer them to exist in or on their bodies, or they are
+tolerant toward them. In the latter case the parasites live at the
+expense of the host, but the host has become used to their being there,
+adapted to them, and the injury that they do, if any, is negligible.</p>
+
+<p>But when a new animal comes into the region from some other locality the
+parasites may be extremely dangerous to it. There are many striking
+examples of this. Most of the people living in what is known as the
+yellow fever belt are immune to the fever. They will not develop it even
+under conditions that would surely mean infection for a person from
+outside this zone. Certain of our common diseases which we regard as of
+little consequence become very serious matters when introduced among a
+people that has never known them before. The cattle of the southern
+states are immune to the Texas fever, but let northern cattle be sent
+south or let the ticks which transmit the disease be taken north where
+they can get on cattle there, and the results are disastrous.</p>
+
+<p>Another striking example and one that is attracting world-wide attention
+just now is the trypanosome that is causing such devastation among the
+inhabitants of central Africa. With the<span class='pagenum'><a name="Page_7" id="Page_7">[Pg 7]</a></span> advent of white men into this
+region and the consequent migration of the natives along the trade
+routes this parasite, which is the cause of sleeping sickness, is being
+introduced into new regions and thousands upon thousands of people are
+dying as a result of its ravages.</p>
+
+
+<p class="center">DISEASES CAUSED BY PARASITES</p>
+
+<p>Some two hundred years ago, after it became known that minute animal
+parasites were associated with certain diseases and were the cause of
+them, it rapidly came to be believed that all our ills were in some way
+caused by such parasites, known or unknown. Further study and
+investigation failed to reveal the intruders in many instances and so it
+began to be doubted whether after all they were responsible for much
+that had been laid at their doors. Then after it was discovered that
+minute plant parasites, bacteria, were responsible for many diseases
+they in turn began to be accused of being the cause of most of the ills
+that the flesh is heir to.</p>
+
+<p>In later years we have come to adopt what seems to be a more reasonable
+view, for we can see and definitely prove that neither of these extreme
+views was correct but that there was much truth in each of them. To-day
+we recognize that certain diseases,<span class='pagenum'><a name="Page_8" id="Page_8">[Pg 8]</a></span> such as typhoid, cholera,
+tuberculosis and many others, are caused by the presence of bacteria in
+the body, and it is just as definitely known that such maladies as
+malaria and sleeping sickness are caused by animal parasites.</p>
+
+<p>Then there is a long list of other epidemic diseases, such as smallpox,
+measles and scarlet fever, the exact cause of which has not been
+determined. Many of these are believed to be due to micro-organisms of
+some kind, and if so they will almost certainly sooner or later be
+found. Curiously enough most of the diseases in this last class and many
+of those in the first are contagious, while all that are caused by
+animal parasites are, as far as is known, infectious but not contagious.</p>
+
+
+<p class="center">INFECTIOUS AND CONTAGIOUS DISEASES</p>
+
+<p>It is important that we keep in mind this distinction. By contagious
+diseases are meant those that are transmitted by contact with the
+diseased person either directly, by touch, or indirectly by the use of
+the same articles, by the breath or effluvial emanations from the body
+or other sources. Small-pox, measles, influenza, etc., are examples of
+this group. By infectious diseases are meant those which are
+disseminated indirectly, that is, in a roundabout way by means of water
+or food or<span class='pagenum'><a name="Page_9" id="Page_9">[Pg 9]</a></span> other substances taken into or introduced into the body in
+some way. Typhoid, malaria, and yellow fever, cholera and others are
+examples of this class. Thus it is evident that all of the contagious
+diseases may be infectious, but many of the infectious diseases are not
+as a rule contagious, although some of them may become so under
+favorable conditions.</p>
+
+<p>Just one example will show the importance of knowing whether a disease
+is contagious or infectious. Until a few years ago it was believed that
+yellow fever was highly contagious and every precaution was taken to
+keep the disease from spreading by keeping the infected region in strict
+quarantine. This often meant much hardship and suffering and always a
+great financial loss. We now know that it is infectious only and not
+contagious, and that all this quarantine was unnecessary. The whole
+fight in controlling an outbreak of yellow fever or in preventing such
+an outbreak is now directed against the mosquito, the sole agent by
+which the disease can be transmitted from one person to another.</p>
+
+
+<p class="center">EFFECT OF THE PARASITE ON THE HOST</p>
+
+<p>We have seen how a few parasites in or on an animal do not as a rule
+produce any appreciable<span class='pagenum'><a name="Page_10" id="Page_10">[Pg 10]</a></span> ill effects. This is of course a most fortunate
+thing for us, for the parasitic germs are everywhere.</p>
+
+<p>There is perhaps "more truth than poetry" in the following newspaper
+jingle:</p>
+
+<p class="poem">
+"Sing a song of microbes,<br />
+<span style="margin-left: 1em;">Dainty little things,</span><br />
+Eyes and ears and horns and tails,<br />
+<span style="margin-left: 1em;">Claws and fangs and stings.</span><br />
+Microbes in the carpet,<br />
+<span style="margin-left: 1em;">Microbes in the wall,</span><br />
+Microbes in the vestibule,<br />
+<span style="margin-left: 1em;">Microbes in the hall.</span><br />
+Microbes on my money,<br />
+<span style="margin-left: 1em;">Microbes in my hair,</span><br />
+Microbes on my meat and bread,<br />
+<span style="margin-left: 1em;">Microbes everywhere.</span><br />
+Microbes in the butter,<br />
+<span style="margin-left: 1em;">Microbes in the cheese,</span><br />
+Microbes on the knives and forks,<br />
+<span style="margin-left: 1em;">Microbes in the breeze.</span><br />
+Friends are little microbes,<br />
+<span style="margin-left: 1em;">Enemies are big,</span><br />
+Life among the microbes is&mdash;<br />
+<span style="margin-left: 1em;">Nothing '<i>infra dig</i>.'</span><br />
+Fussy little microbes,<br />
+<span style="margin-left: 1em;">Millions at a birth,</span><br />
+Make our flesh and blood and bones,<br />
+<span style="margin-left: 1em;">Keep us on the earth."</span><br />
+</p>
+
+<p>While of course most of these microbes are to be regarded as absolutely
+harmless and some as very useful, many have the power to do much injury
+if<span class='pagenum'><a name="Page_11" id="Page_11">[Pg 11]</a></span> the proper conditions for their rapid development should at any time
+exist. While the size of the parasite is always a factor in the damage
+that it may do to the host the factor of numbers is perhaps of still
+greater importance because of the power of very rapid multiplication
+possessed by so many of the smaller forms.</p>
+
+<p>Certain minute parasites in the blood may cause little or no
+inconvenience, but should they begin to multiply too rapidly some of the
+capillaries may be filled up and trouble thus result. Or take some of
+the larger forms. A few intestinal worms may cause no appreciable effect
+on the host, but as soon as their numbers increase serious conditions
+may come about simply by the presence of the great masses in the host
+even if they were not robbing it of its nourishment. Many instances are
+known where such worms have formed masses that completely clogged up the
+alimentary canal. Such injuries as these may be regarded as mechanical
+injuries. Some parasites injure the host only when they are laying their
+eggs or reproducing the young. These may clog up passages or some of
+them may be carried to some more sensitive part of the body where the
+damage is done. The guinea-worm of southwestern Asia and of Africa lives
+in the body of its host for nearly a year sometimes attaining<span class='pagenum'><a name="Page_12" id="Page_12">[Pg 12]</a></span> a great
+length and migrating through the connective tissue to different parts of
+the body causing no particular inconvenience until it is ready to lay
+its eggs when it comes to the surface and then great suffering may
+result. The African eye-worm is another example of a parasite causing
+mechanical injury only at certain times. It works in the tissues of the
+body sometimes for a long while, doing no harm unless it finds its way
+to the connective tissue of the eyeball.</p>
+
+<p>It is known that many of the germs which cause diseases cannot get into
+the body unless the protecting membranes have first been injured in some
+way. Thus the germs that cause plague and lockjaw find their way into
+the system principally through abrasions of the skin. Many physicians
+have come to believe that the typhoid fever germ cannot get into the
+body from the intestine where it is taken with our food or drink unless
+the walls of the intestine have been injured in some way. It is well
+known that of the many parasites that inhabit the alimentary canal some
+rasp the surface and others bore through into the body cavity. This in
+itself may not be a serious thing, but if the mechanical injury thus
+caused opens the way for malignant germs, baneful results may follow.
+Even that popular disease appendicitis is believed to be due<span class='pagenum'><a name="Page_13" id="Page_13">[Pg 13]</a></span> sometimes
+to the injury caused by the work of parasites in the appendix.</p>
+
+<p>Parasites may cause morphological or structural changes in the tissues
+of their hosts. The stimulation caused by their presence may result in
+swellings or excresences or other abnormal growths. Interesting examples
+of this are to be found in the way in which pearls are formed in various
+mollusks. In the pearl oysters of Ceylon occur some of the best pearls.
+If these are carefully sectioned there may usually be found at the
+center the remains of certain cestode larv&aelig; whose presence in the oyster
+caused it to deposit the nacreous layers that make up the pearl. Other
+parasites cause similar growths in various shellfish. The great
+enlargements of the arms or legs or other parts of the body seen in
+patients affected with elephantiasis is an abnormal growth due to the
+presence of the parasitic filar&aelig; in some of the lymph-glands where they
+have come to rest.</p>
+
+<p>Finally, the parasite may exert a direct physiological effect on the
+host. This is evident when the parasite demands and takes a portion of
+the nourishment that would otherwise go to the building up of the host.
+Sometimes this is of little importance, but at other times it may be a
+matter of life or death to the infected animal. The physiological<span class='pagenum'><a name="Page_14" id="Page_14">[Pg 14]</a></span>
+effect produced may be due to the toxins or poisonous matters that are
+given off by the parasite while it is living in the host's body. Thus it
+is believed that the malarial patients usually suffer less from the
+actual loss of red blood-corpuscles that are destroyed by the parasite
+than they do from the effects of the poisonous excretions that are
+poured into the circulation when the thousands of corpuscles break to
+release the parasites.</p>
+
+<p>One other point in regard to the relation of the parasite to its host
+and this part of the subject may be dismissed. From our standpoint we
+look upon the presence of parasites in the body as an abnormal
+condition. From a biological standpoint their presence there is
+perfectly normal; it is a necessary part of their life. We think that
+they have no business there, but from the viewpoint of the parasites
+their whole business is to be just there. If they are not, they perish.
+And when we take a dose of quinine or other drug we are killing or
+driving from their homes millions of these little creatures who have
+taken up their abode with us for the time being. But they interfere with
+our health and comfort, so they must go.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_15" id="Page_15">[Pg 15]</a></span></p>
+<h2><a name="CHAPTER_II" id="CHAPTER_II"></a>CHAPTER II</h2>
+
+<h3>BACTERIA AND PROTOZOA</h3>
+
+
+<p class="center">BACTERIA</p>
+
+<div class="figdrop">
+<img src="images/dropo.jpg" width="75" height="76" alt="dropo" title="" />
+</div>
+<p class="noin"><span class="caps">n</span> the border line between the plant and the animal worlds are many
+forms which possess some of the characteristics of both. Indeed when an
+attempt is made to separate all known organisms into two groups one is
+immediately confronted with difficulties. In looking over the text-books
+of Botany we will find that certain low forms are discussed there as
+belonging with the plants, and on turning to the manuals of Zo&ouml;logy we
+will find that the same organisms are placed among the lowest forms of
+animals. The question is of course of little actual importance from
+certain points of view. It serves, however, to show the close relation
+of all forms of life, and from a medical standpoint it may be of very
+great importance owing to the difference in the life-habits, methods of
+reproduction and methods of transmission of many of the forms that cause
+disease. We have already seen that none of the diseases that<span class='pagenum'><a name="Page_16" id="Page_16">[Pg 16]</a></span> are caused
+by animal parasites is contagious, while many of those caused by
+bacteria are both contagious and infectious.</p>
+
+<p>Just over on the plant side of this indefinite border line are the
+minute organisms known as bacteria. Their numbers are infinite and they
+are found everywhere. The majority of them are beneficial to mankind in
+one way or another, but some of them cause certain of the diseases that
+we will have to discuss later so attention may be called here to a few
+of the important facts in regard to their organization and life-history
+in order that we may better understand how they may be so easily
+transferred from one host to another.</p>
+
+<p>Although these bacilli are so extremely minute (<a href="#Fig_7">Fig. 7</a>), some of them so
+small that they cannot be seen with the most powerful microscopes, they
+differ in size, shape, methods of division and spore-formation. Each
+species makes a characteristic growth on gelatin, agar or other media
+upon which it may be cultivated. In this way as well as by the
+inoculation of animals the presence of the ultramicroscopic kinds may be
+demonstrated.</p>
+
+<p>The method of reproduction is very simple. They increase to a certain
+point in size, then divide. This growth and division takes place very
+rapidly. Twenty to thirty minutes is sufficient time in some<span class='pagenum'><a name="Page_17" id="Page_17">[Pg 17]</a></span> cases for
+a just-divided cell to attain full size and divide again. Thus in a few
+days time the number of bacteria resulting from a single individual
+would be inconceivable if they should all develop.</p>
+
+<p>Fortunately for us, however, they do not all multiply so rapidly as this
+and besides there are natural checks, not the least of which are the
+substances given off by the bacteria themselves in their growth and
+development. Such excretions often serve to inhibit further
+multiplication. Sometimes, though not often, they form spores which not
+only provide for a more rapid multiplication, but enable the organism to
+live under conditions that would otherwise prove fatal to it.</p>
+
+<p>Bacteria may be conveniently grouped under two heads: those that live
+upon dead organic matter, known as the saprophytic forms, and those that
+are found in living plants or animals, the true parasites. Such a
+grouping is not always entirely satisfactory, for many of the kinds that
+live saprophytically under normal conditions may become parasitic if
+opportunity offers, and also many of those that are usually regarded as
+parasitic may be grown in cultures of agar or other media, under which
+conditions they may be regarded as living saprophytically.</p>
+
+<p>It is this power of easily adapting themselves<span class='pagenum'><a name="Page_18" id="Page_18">[Pg 18]</a></span> to different conditions
+that makes many of the kinds dangerous. The bacillus which causes
+tetanus or lockjaw will illustrate this. It is a rather common bacillus
+in soil in many localities. As long as it remains there it is of no
+special importance, but if it is introduced into the body through a
+scratch or any other wound it becomes a very serious matter.</p>
+
+<p>We may say, then, that the effect the bacillus has on the host depends
+largely on the host. Not only does it depend on what the host is, but
+the particular condition of the host at the time of infection is of
+importance. Children are subject to many diseases that adults seldom
+have. Hunger, thirst, fatigue, exposure and other factors may make a
+person susceptible to the actions of certain bacteria that would be
+harmless under other conditions.</p>
+
+<p>The minute size and great numbers of the bacteria make their
+dissemination a comparatively simple matter. They may be carried in the
+air as minute particles of dust; they may be carried in water or milk;
+they may be carried on the clothing or on the person from one host to
+another, or they may be disseminated in scores of other ways. In other
+chapters, particularly the one dealing with the house-fly and typhoid,
+we shall see how it is<span class='pagenum'><a name="Page_19" id="Page_19">[Pg 19]</a></span> that insects are often important factors in
+spreading some of the most dreaded of the bacterial diseases.</p>
+
+
+<p class="center">THE PROTOZOA</p>
+
+<p>The Protozoa, or one-celled animals, belonged to an unknown world before
+the invention of the microscope. The first of these instruments enabled
+the early observers to see some of the larger and more conspicuous
+members of the group and each improvement of the microscope has enabled
+us to see more and more of them and to study in detail not only the
+structure but to follow the life-history of many of them.</p>
+
+<p><i>The Am&#339;ba.</i> With some, as the common am&#339;ba (<a href="#Fig_8">Fig. 8</a>), a minute
+little form that is to be found in the slime at the bottom of almost any
+body of water, the life-history is extremely simple. The organism itself
+consists of a minute particle of protoplasm, a single cell with no
+definite shape or body-wall and no specialized organs or apparatus for
+carrying on the life-functions. It lives in the slime or ooze in fresh
+or salt water, takes its food by simply flowing over the particle that
+is to be ingested, grows to a certain limit of size, then divides into
+two more or less equal parts, each part becoming a new animal that goes
+on with its development<span class='pagenum'><a name="Page_20" id="Page_20">[Pg 20]</a></span> as did the parent form. This process of growth
+and division may go on for many generations, but cannot continue
+indefinitely unless there is a conjugation of two separate individuals.
+This process of conjugation is just the opposite to that of division.
+Two am&#339;ba flow together and become one. It seems to rejuvenate the
+organism so that it is able to go on with its division and thus fulfil
+its life-mission which is the same for these lowly animals as with the
+higher, that of perpetuating the species.</p>
+
+<p><i>Classes of Protozoa.</i> The group or Phylum Protozoa is divided into four
+smaller groups or classes. The am&#339;ba belongs to the lowest of these,
+the Rhizopoda. Rhizopoda means "root-footed," and the name is applied to
+these animals because most of them move about by means of root-like
+processes known as pseudopodia or "false feet." This is by far the
+largest class and contains thousands of forms, mostly living in salt
+water but there are many fresh-water species. They are non-parasitic,
+but some of them by their presence in the body may cause such diseases
+as dysentery, etc.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_7" id="Fig_7"></a>
+<img src="images/fig7.jpg" width="300" height="304" alt="Fig. 7" title="" />
+<span class="caption"><span class="smcap">Fig. 7</span>&mdash;Typhoid Fever bacilli. (After Muir and Ritchie.)</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_8" id="Fig_8"></a>
+<img src="images/fig8.jpg" width="350" height="359" alt="Fig. 8" title="" />
+<span class="caption"><span class="smcap">Fig. 8</span>&mdash;<i>Am&#339;ba</i>, showing the forms assumed by a single
+individual in four successive changes. (From Kellogg&#39;s Elementary
+Zo&ouml;l.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_9" id="Fig_9"></a>
+<img src="images/fig9.jpg" width="400" height="261" alt="Fig. 9" title="" />
+<span class="caption"><span class="smcap">Fig. 9</span>&mdash;<i>Euglina virdis.</i> (After Saville Kent.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_10" id="Fig_10"></a>
+<img src="images/fig10.jpg" width="400" height="243" alt="Fig. 10" title="" />
+<span class="caption"><span class="smcap">Fig. 10</span>&mdash;<i>Spirocheta duttoni</i>, &times; 4500. (After Breinl and Carter.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_21" id="Page_21">[Pg 21]</a></span></p><p>The next class which may be known as the whip-bearers (<i>Mastigophora</i>)
+includes those Protozoa that move by fine undulating processes called
+flagella. One of the common representatives of this class is the little
+green <i>Euglena</i> (<a href="#Fig_9">Fig. 9</a>), whose presence in standing ponds and puddles
+often imparts a greenish color to the water. Then in the salt water near
+the surface there are often myriads of minute <i>Noctiluca</i> whose
+wonderfully phosphorescent little bodies glow like coals of fire when
+the water is disturbed at night. Although this class contains fewer
+forms than the preceding some of these have within recent years been
+found to be of great importance because they live as parasites on man
+and other animals. The trypanosome whose presence in the blood and
+tissues of the patient causes that dreadful disease which ends in
+sleeping sickness belongs here as well as do several other similar kinds
+that produce serious troubles for various mammals and birds. The
+Spiroch&aelig;ta, about which there has been so much recent discussion, also
+belong here. These are simple spiral-like forms (<a href="#Fig_10">Fig. 10</a>), that are
+sometimes classed with the simple plants, bacteria, but Nuttall and
+others have shown very definitely that they should be classed with the
+simplest animals, the Protozoans. These are the cause of relapsing
+fevers in man and of several diseases of domestic animals. It is
+believed by certain eminent zo&ouml;logists that when the germ that causes
+yellow fever is discovered it will be found to belong to this group.</p>
+
+<p><span class='pagenum'><a name="Page_22" id="Page_22">[Pg 22]</a></span></p><p>The members of the class Infusoria, so called because they were early
+found to be abundant in various infusions, are characterized by numerous
+fine cilia or hair-like organs by means of which the organism moves
+about and procures its food. The well-known "slipper animalcule"
+(<i>Paramoecium</i>) (<a href="#Fig_11">Fig. 11</a>), and the "bell-animalcule" (<i>Vorticella</i>)
+(<a href="#Fig_12">Fig. 12</a>) are two common representatives. The <i>Paramoecia</i> were the
+animals mostly used by Jennings in his wonderfully interesting
+experiments on the behavior of these lowly forms of life. He showed that
+they always reacted in a certain definite way in response to particular
+stimuli, and he was led to believe that he could see "what must be
+considered the beginnings of intelligence and of many other qualities
+found in the higher animals." A species of <i>Vorticella</i> was probably the
+first Protozoan that was ever observed. An old Dutch microscopist, Anton
+von Leeuwenhoek, in 1675, while studying with lenses of his own
+manufacture, discovered and described forms which undoubtedly belong to
+this genus. Few if any of the Infusoria are pathogenic, although some
+are said to be associated with certain intestinal diseases both in man
+and the lower animals (<a href="#Fig_13">Fig. 13</a>).</p>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 11 and 12">
+<tr>
+ <td class="tdf"><a name="Fig_11" id="Fig_11"></a><img src="images/fig11.jpg" width="250" height="706" alt="Fig. 11" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 11</span></span></td>
+ <td class="tdf"><a name="Fig_12" id="Fig_12"></a><img src="images/fig12.jpg" width="250" height="713" alt="Fig. 12" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 12</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 11</span>&mdash;<i>Paramoecium.</i> (From Kellogg's Elementary
+Zo&ouml;l.)</p>
+<p class="caption2"><span class="smcap">Fig. 12</span>&mdash;<i>Vorticella</i>, one individual with the stalk
+coiled, the other with the stalk extended. (From Kellogg's Elementary
+Zo&ouml;l.)</p></td>
+</tr>
+</table>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_13" id="Fig_13"></a>
+<img src="images/fig13.jpg" width="400" height="291" alt="Fig. 13" title="" />
+<span class="caption"><span class="smcap">Fig. 13</span>&mdash;Pathogenic Protozoa; a group of intestinal
+parasites. <i>A, B, Megastoma entericum, C, Balantidum entozoon.</i>
+(After Calkins.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_23" id="Page_23">[Pg 23]</a></span></p><p>The last class, the Sporozoa, or the spore-forming animals, while small
+in the number of known species, only about three hundred kinds being
+known, is extremely important. A number of diseases in man and other
+animals are due to the presence of these Sporozoans, for they are all
+parasitic. Few if any animals are exempt from their attacks. They even
+attack other minute Protozoa. One hundred and fifty-seven species have
+been recorded as attacking insects, one hundred species attack birds,
+fifty-two reptiles, eighty crustaceans, twenty-two fish, and so through
+the list. Ten have been recorded as attacking man. In some instances the
+parasite is always present in the host and some hosts may harbor several
+different species of Sporozoa.</p>
+
+<p>Very little work had been done on this group of parasites prior to 1900.
+Since that time most of the species that we now know have been
+discovered, and within the last few years the life-histories of many of
+these have been worked out quite completely. No other group of animals
+is being studied more to-day by both the physicians and biologists.</p>
+
+<p>The Sporozoa vary greatly in appearance, organization and life-history.
+They are so very plastic that they can adapt themselves readily to their
+various hosts, hence we have a great variety of forms. But they all
+agree in certain characters; all take their food and oxygen and carry on
+excretory<span class='pagenum'><a name="Page_24" id="Page_24">[Pg 24]</a></span> processes by osmosis, <i>i.e.</i>, through the body-wall; all are
+capable of some kind of locomotion, some have one or more flagella,
+others move by a pseudopod movement. Some are capable of moving from
+cell to cell in the body as do the white blood-corpuscles. They all
+agree in the production of spores&mdash;hence the name.</p>
+
+<p>At certain stages in their development the nucleus within the body of
+the organism divides again and again until there are a great many
+daughter nuclei, each accompanied by a small mass of protoplasm, often
+inclosed in a little sac or cyst of its own. This is the process of
+spore-formation and we see that from a single individual we may have by
+division, not two animals as in the am&#339;ba, but a score or more of
+them. The little cysts or capsules that inclose them enable them to
+resist without injury many vicissitudes that would otherwise destroy
+them. They may dry up or freeze or lie for a long time in the ground or
+water until the time comes when they are introduced into another host.</p>
+
+<p>The class Sporozoa is divided into five small groups or orders. Nearly
+all of these contain forms that are of more or less importance, but the
+ones that live in the blood-cells (<i>H&aelig;mosporidiida</i>) are of the most
+interest to us because the parasites<span class='pagenum'><a name="Page_25" id="Page_25">[Pg 25]</a></span> that cause the malarial fevers and
+various other diseases belong here. These are dependent on two hosts for
+their existence, the sexual generation usually occuring in an insect or
+other invertebrate and the asexual generation in some vertebrate.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_26" id="Page_26">[Pg 26]</a></span></p>
+<h2><a name="CHAPTER_III" id="CHAPTER_III"></a>CHAPTER III</h2>
+
+<h3>TICKS AND MITES</h3>
+
+<div class="figdrop">
+<img src="images/dropt.jpg" width="75" height="77" alt="dropt" title="" />
+</div>
+<p class="noin"><span class="caps">he</span> other group or Phylum of animals with which we will be particularly
+concerned is known as the Arthropoda, which means "jointed-feet" and
+includes the crayfish, crabs, spiders, mites, ticks and insects. Of
+these only the last three are of interest to us now. It is customary to
+speak of spiders, mites and ticks as insects, but as they have four
+pairs of legs, instead of three pairs, in the adult stage, and as their
+bodies are not divided into three distinct regions as in the insects,
+they are placed in a different class.</p>
+
+
+<p class="center">GENERAL CHARACTERS OF TICKS</p>
+
+<p>The ticks are all comparatively large, that is, they are all large
+enough to be seen with the unaided eye even in their younger stages and
+some grow to be half an inch long. When filled with blood the tough
+leathery skin becomes much distended often making the creature look more
+like a large seed<span class='pagenum'><a name="Page_27" id="Page_27">[Pg 27]</a></span> than anything else (<a href="#Fig_14">Fig. 14</a>). This resemblance is
+responsible for some of the popular names, such as "castor-bean tick,"
+etc.</p>
+
+<p>The legs of most species are comparatively short, and the head is small
+so that they are often hardly noticeable when the body is distended. The
+sucking beak which is thrust into the host when the tick is feeding is
+furnished with many strong recurved teeth which hold on so firmly that
+when one attempts to pull the tick away the head is often torn from the
+body and left in the skin. Unless care is taken to remove this, serious
+sores often result.</p>
+
+<p>Ticks are wholly parasitic in their habits. Some of them live on their
+host practically all their lives, dropping to the ground to deposit
+their eggs when fully mature. Others leave their host twice to molt in
+or on the ground. The female lays her eggs, 1,000 to 10,000 of them, on
+the ground or just beneath the surface. The young "seed-ticks" that
+hatch from these in a few days soon crawl up on some near-by blade of
+grass or on a bush or shrub and wait quietly and patiently until some
+animal comes along. If the animal comes close enough they leave the
+grass or other support and cling to their new-found host and are soon
+taking their first meal. Of course thousands of them are disappointed<span class='pagenum'><a name="Page_28" id="Page_28">[Pg 28]</a></span>
+and starve before their host appears, but as they are able to live for a
+remarkably long time without taking food their patience is often
+rewarded and the long fast ended.</p>
+
+<p>Those species which drop to the ground to molt must again climb to some
+favorable point and wait for another host on which they may feed for a
+while. Then they drop to the ground for a second molt and if they are
+successful in gaining a new host for the third time they feed and
+develop until fully mature and the female is ready to lay her eggs. The
+Texas fever tick, and some others, as we shall see, do not drop to the
+ground to molt but once having gained a host remain on it until ready to
+deposit their eggs.</p>
+
+<p>The young ticks have only six legs (<a href="#Fig_15">Fig. 15</a>) but after the first molt
+they all have eight.</p>
+
+
+<p class="center">TICKS AND DISEASE</p>
+
+<p><i>Texas Fever.</i> Ever since stockmen began driving southern cattle into
+states further north it has been noted that the roads over which they
+were driven became a source of great danger to northern cattle. Often
+80% to 90% of the native cattle died after a herd of southern cattle
+passed through their region and the losses became so great that both
+state and national laws were passed prohibiting the driving or shipping
+of southern cattle into northern states.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_14" id="Fig_14"></a>
+<img src="images/fig14.jpg" width="350" height="365" alt="Fig. 14" title="" />
+<span class="caption"><span class="smcap">Fig. 14</span>&mdash;Castor Bean Tick (<i>Ixodes ricinus</i>) not fully
+gorged.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_15" id="Fig_15"></a>
+<img src="images/fig15.jpg" width="350" height="286" alt="Fig. 15" title="" />
+<span class="caption"><span class="smcap">Fig. 15</span>&mdash;Texas fever tick, just hatched; has only six legs.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_16" id="Fig_16"></a>
+<img src="images/fig16.jpg" width="350" height="373" alt="Fig. 16" title="" />
+<span class="caption"><span class="smcap">Fig. 16</span>&mdash;Texas fever tick (<i>Margaropus annulatus</i>) young adult not fully gorged.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_17" id="Fig_17"></a>
+<img src="images/fig17.jpg" width="400" height="388" alt="Fig. 17" title="" />
+<span class="caption"><span class="smcap">Fig. 17</span>&mdash;<i>Amblyomma variegatum</i> several ticks belonging
+to this genus transmit <i>Piroplasma</i> which cause various diseases of
+domestic animals.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_29" id="Page_29">[Pg 29]</a></span></p><p>But for years the cause of this fever, which came to be known as the
+Texas fever, was not known. The southern cattle themselves seemed
+healthy enough and it was difficult to understand how they could give
+the disease to the others. It was early noticed, too, that it was not
+necessary for the northern cattle to come in direct contact with the
+others in order to contract the disease. Indeed the disease was not
+contracted in this way at all. All that was necessary for them was to
+pass along the same roads or feed in the same pastures or ranges. Still
+more puzzling was the fact that these places did not seem to become a
+source of danger until some weeks after the southern cattle had passed
+over them and then they might remain dangerous for months.</p>
+
+<p>In 1886 Dr. Theobald Smith of the Bureau of Animal Industry, United
+States Department of Agriculture, found that the fever was caused by the
+presence in the infected cattle of a minute Sporozoan parasite
+(<i>Piroplasma bigeminum</i>). Further investigations and experiments proved
+conclusively that this parasite was transmitted from the infected to the
+well animal only by the common cattle tick now known as the Texas fever
+tick (<a href="#Fig_16">Fig. 16</a>).</p>
+
+<p><span class='pagenum'><a name="Page_30" id="Page_30">[Pg 30]</a></span></p><p>The infection is not direct, that is, the tick does not feed on one
+host then pass to another carrying the disease germs with it. Unlike
+many other ticks the Texas fever tick does not leave its host until it
+is fully developed. When the female is full grown and gorged she drops
+to the ground and lays from 2,000 to 4,000 eggs which soon hatch into
+the minute "seed-ticks" which make their way to the nearest blade of
+grass or weed or shrub and patiently wait for the cattle to come along.</p>
+
+<p>If the mother tick had been feeding on an animal that was infected with
+the Texas fever parasite, her body was filled with the minute organisms
+of which some found their way into the eggs so that the young ticks
+hatching from them were already infected and ready to carry the
+infection to the first animal they fed upon.</p>
+
+<p>It took many years of hard patient work to learn all this, but the
+knowledge thus obtained cleared up much of the mystery in connection
+with the occurrence of the fever in the north and, as we shall see,
+suggested the possibility of other diseases being communicated in the
+same way.</p>
+
+<p>It was found that the southern cattle in the region where the ticks
+occur normally, usually have a mild attack of the disease when they are
+young and although they may be infected with the<span class='pagenum'><a name="Page_31" id="Page_31">[Pg 31]</a></span> parasite all the rest
+of their lives it does not affect them seriously. These cattle are
+almost always infected with ticks, and when taken north where the ticks
+do not occur naturally and where the cattle are therefore non-immune,
+some of the mature ticks drop to the ground and lay their eggs which in
+a few weeks hatch out and are ready to infect any animal that passes by.
+The northern cattle not being used to the disease soon sicken and die.</p>
+
+<p>It is estimated that the annual loss due to this disease and the ravages
+of the tick in the United States is over $100,000,000, so of course most
+determined efforts are being made to stamp it out. Formerly various
+devices for dipping the tick-infested cattle into some solution that
+would kill the ticks were resorted to, but it was always expensive and
+never very satisfactory. The immunizing of the cattle by inoculating
+them when they were young with infected blood has been practised. Very
+recent investigations have shown that it is possible and practicable to
+rid pastures of ticks by a system of feed-lots and pasture rotation. The
+aim is to have as many of the ticks as possible drop to the ground on
+land where they may be destroyed and to so regulate the use of the
+pasture that the ticks in all of them may eventually be left to starve.</p>
+
+<p>Several similar diseases of cattle, many of them<span class='pagenum'><a name="Page_32" id="Page_32">[Pg 32]</a></span> probably identical
+with Texas fever, occur in other parts of the world where the losses are
+sometimes appalling. Horses, sheep, dogs, and other animals are also
+affected with diseases caused by the same group of Protozoan parasites.
+Most of them have been shown to be transmitted by various species of
+ticks (<a href="#Fig_17">Fig. 17</a>) so that from an economical standpoint these little pests
+are becoming of prime importance. Not only do they transmit the disease
+germs that infect domestic animals but they are known to be responsible
+for at least two diseases of men, Rocky Mountain spotted fever and the
+relapsing fevers.</p>
+
+<p><i>Spotted Fever.</i> The first of these is a disease that for some years has
+been puzzling the physicians in Idaho and Montana and other mountainous
+states. A few years ago certain observers recorded finding Protozoan
+parasites in the blood of those suffering from the disease, and although
+more recent investigations have failed to confirm these particular
+observations it is now quite generally believed that the disease is
+caused by some such parasite and that the organism is transferred from
+one host to another by certain species of ticks that live on wild
+mammals of the region where the disease exists. Dr. H.T. Ricketts, who
+has made a special study of the disease, has shown:</p>
+
+<p><span class='pagenum'><a name="Page_33" id="Page_33">[Pg 33]</a></span></p><div class="blockquot"><p>"1. That the period of activity of the disease is limited to the
+season during which the adult female and male ticks attack man.</p>
+
+<p>"2. That in practically all cases of this disease it can be shown
+that the patient has been bitten by a tick.</p>
+
+<p>"3. That the period between the tick bite and the onset of the
+disease in the many animals he has experimented with corresponds
+very closely to this period as observed in man.</p>
+
+<p>"4. That infected ticks are to be found in the locality where the
+disease occurs.</p>
+
+<p>"5. That the virus of spotted fever is very intimately associated
+with the tissues of the tick's body as is shown by the fact that
+the female passes the infection on to her young through her eggs,
+and further, by the observation that in either of the two earlier
+stages of the life cycle the disease may be contracted by biting a
+sick animal and communicated to other animals after molting or even
+after passing through an intermediate stage." </p></div>
+
+<p>Professor R.A. Cooley of Montana, from whose report the above quotation
+is taken, has also made studies of the habits of the tick and believes
+there can be no doubt that it is the disseminator of the disease.</p>
+
+<p><i>Relapsing Fever.</i> The relapsing fever is an infectious disease or
+possibly a group of closely related<span class='pagenum'><a name="Page_34" id="Page_34">[Pg 34]</a></span> infectious diseases occurring in
+various parts of the world. Occasionally it is introduced into America,
+but it does not seem to spread here. It has been shown that the disease
+is communicated from one person to another by means of blood-sucking
+insects. In Central Africa where the disease is very prevalent a certain
+common tick (<i>Ornithodoros moubata</i>) (<a href="#Fig_18">Fig. 18</a>) is known to transmit the
+disease. This tick lives in the resting places and around the huts of
+the natives and has habits very similar to the bedbug of other climes,
+feeding at night and hiding during the day. It attacks both man and
+beast and is one of the most dreaded of all the African pests.</p>
+
+<p>Nathan Bank, our foremost authority on ticks, in summing up the evidence
+against them says:</p>
+
+<div class="blockquot"><p>"It is therefore evident that all ticks are potentially dangerous.
+Any tick now commonly infesting some wild animal, may, as its
+natural host becomes more uncommon, attach itself to some domestic
+animal. Since most of the hosts of ticks have some blood-parasites,
+the ticks by changing the host may transplant the blood-parasites
+into the new host producing, under suitable conditions, some
+disease. Numerous investigators throughout the world are studying
+this phase of tick-life, and many discoveries will doubtless
+signalize the coming years." </p></div>
+
+
+<p><span class='pagenum'><a name="Page_35" id="Page_35">[Pg 35]</a></span></p><p class="center">MITES</p>
+
+<p>The mites are closely related to the ticks, and although none of them
+has yet been shown to be responsible for the spread of any disease their
+habits are such that it would be entirely possible for some to transmit
+certain diseases from one host to another, from animal to animal, from
+animal to man, or from man to man. A number of these mites produce
+certain serious diseases among various domestic animals and a few are
+responsible for certain diseases of men.</p>
+
+<p><i>Face-mites.</i> Living in the sweat-glands at the roots of hairs and in
+diseased follicles in the skin of man and some domestic animals are
+curious little parasites that look as much like worms as mites (<a href="#Fig_19">Fig.
+19</a>). Such diseased follicles become filled with fatty matter, the upper
+end becomes hard and black and in man are known as blackheads. If one of
+these blackheads is forced out and the fatty substance dissolved with
+ether the mites may be found in all stages of development. The young
+have six legs, the adult eight. The body is elongated and transversely
+wrinkled. In man they are usually found about the nose and chin and neck
+where they do no particular harm except to mar the appearance of the
+host and to indicate<span class='pagenum'><a name="Page_36" id="Page_36">[Pg 36]</a></span> that his skin has not had the care it should have.
+Very recently certain investigators have found that the lepr&aelig; bacilli
+are often closely associated with these face mites and believe that they
+may possibly aid in the dissemination of leprosy. It is also thought
+that they may sometimes be the cause of cancer, but as yet these
+theories have not been proven by any conclusive experiment.</p>
+
+<p>In dogs and cats these same or very similar parasites cause great
+suffering. In bad cases the hair falls out and the skin becomes scabby.
+Horses, cattle and sheep are also attacked. The disease caused by these
+mites on domestic animals is not usually considered curable except in
+its very early stages when salves or ointments may help some.</p>
+
+<p><i>Itch-mites.</i> "As slow as the seven-years' itch" is an expression, the
+meaning of which many could appreciate from personal experience, for it
+certainly seemed to take no end of time to get rid of the itch once it
+was contracted. Just why seven years should have been set for the limit
+of the disease is not clear, for if the little roundish mites that cause
+the disease live for seven years on a host they are not going to move
+out voluntarily even if their seven-year lease has expired.</p>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_18" id="Fig_18"></a>
+<img src="images/fig18.jpg" width="250" height="573" alt="Fig. 18" title="" />
+<span class="caption"><i>Fig. 18</i>&mdash;<i>Ornithodorus moubata</i>, the Tick that Transmits
+Relapsing Fever. From Boyce&#39;s &quot;Mosquito or Man.&quot;</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_19" id="Fig_19"></a>
+<img src="images/fig19.jpg" width="250" height="470" alt="Fig. 19" title="" />
+<span class="caption"><span class="smcap">Fig. 19</span>&mdash;The follicle mite (<i>Demodex folliculorum</i>).
+(After Murray.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_20" id="Fig_20"></a>
+<img src="images/fig20.jpg" width="400" height="269" alt="Fig. 20" title="" />
+<span class="caption"><span class="smcap">Fig. 20</span>&mdash;Itch-mite (<i>Sarcoptes scabiei</i>). (After Murray.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_21" id="Fig_21"></a>
+<img src="images/fig21.jpg" width="400" height="216" alt="Fig. 21" title="" />
+<span class="caption"><span class="smcap">Fig. 21</span>&mdash;Harvest-mites or &quot;jiggers.&quot; (<i>Leptus irritaus</i> and <i>L. americanus.</i>) (After Riley.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_37" id="Page_37">[Pg 37]</a></span></p><p>The minute whitish mites (<a href="#Fig_20">Fig. 20</a>) that cause this disgusting disease
+are barely visible to the naked eye. They are usually very sluggish but
+become more active when warmed. They live in burrows just beneath the
+outer layer of skin, sometimes extending deeper and causing most intense
+itching. As the female burrows, she lays her eggs from which come the
+young mites that are to spread the infection. Various sulphur ointments
+and washes are used as remedies. Cleanliness will prevent infection.</p>
+
+<p>Closely related to the itch-mite of man (<i>Sarcoptes scabiei</i>) are
+several kinds attacking domestic animals, causing mange, scab, etc. The
+variety infesting horses burrows in the skin and produces sores and
+scabs, and is a source of very great annoyance. These mites may also
+migrate to man. Tobacco water and sulphur ointments are used as
+remedies.</p>
+
+<p>Horses and cattle are also infested by other mites (<i>Psoroptes
+communis</i>) which cause the common mange. These do not burrow into the
+skin but live outside in colonies, feeding on the skin and causing
+crusts or scabs. The inflammation causes the animal to scratch and rub
+constantly and often causes the loss of much of the hair.</p>
+
+<p><i>Harvest-mites.</i> A score or more of different varieties of mites cause
+many other diseases of domestic animals, such as the scab of sheep and
+hogs<span class='pagenum'><a name="Page_38" id="Page_38">[Pg 38]</a></span> and chickens, various other manges of the horses and cattle and
+dogs, etc. But we need to call attention to just one more example, that
+of the harvest-mites or jiggers (<a href="#Fig_21">Fig. 21</a>). Professor Otto Lugger, from
+whose report on the <i>Parasites of Man and Domestic Animals</i> most of
+these notes in regard to the mites are taken, thus feelingly refers to
+this pest.</p>
+
+<div class="blockquot"><p>"About the very worst pests of man and domesticated animals are the
+Harvest-bugs, Red-bugs or Jiggers.... Men and animals passing
+through low herbage that harbors them are attacked by these pests,
+which, whenever they succeed in finding a host, burrow in and under
+the skin, causing intolerable itching and sores, the latter caused
+by the feverish activity of the finger-nails of the host, if that
+should be a man, whose energy in scratching, apparently, cannot be
+controlled and who is bound forcibly to remove the intruders. The
+writer has been there! Those who have ever passed through meadows
+infested with red-bugs will remember the occasion." </p></div>
+
+<p>Horses, cattle, dogs and cats and other animals suffer also. Again
+sulphur ointments are the best remedies.</p>
+
+<div class="blockquot"><p>"The normal food of these mites must, apparently, consist of the
+juices of plants, and the love of blood proves ruinous to those
+individuals which get a chance<span class='pagenum'><a name="Page_39" id="Page_39">[Pg 39]</a></span> to indulge it. For, unlike the true
+chigoe, the female of which deposits eggs in the wound she makes,
+these harvest-mites have no object of the kind, and when not killed
+at the hands of those they torment they soon die victims to their
+sanguinary appetite."</p></div>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_40" id="Page_40">[Pg 40]</a></span></p>
+<h2><a name="CHAPTER_IV" id="CHAPTER_IV"></a>CHAPTER IV</h2>
+
+<h3>HOW INSECTS CAUSE OR CARRY DISEASE</h3>
+
+<div class="figdrop">
+<img src="images/dropi.jpg" width="75" height="76" alt="dropi" title="" />
+</div>
+<p class="noin"><span class="caps">t</span> has been estimated that there are about four thousand species or
+kinds of Protozoans, about twenty-five thousand species of Mollusks,
+about ten thousand species of birds, about three thousand five hundred
+species of mammals, and from two hundred thousand to one million species
+of insects, or from two to five times as many kinds of insects as all
+other animals combined.</p>
+
+<p>Not only do the insects preponderate in number of species, but the
+number of individuals belonging to many of the species is absolutely
+beyond our comprehension. Try to count the number of little green aphis
+on a single infested rose-bush, or on a cabbage plant; guess at the
+number of mosquitoes issuing each day from a good breeding-pond;
+estimate the number of scale insects on a single square inch of a tree
+badly infested with San Jos&eacute; scale; then try to think how many more
+bushes or<span class='pagenum'><a name="Page_41" id="Page_41">[Pg 41]</a></span> trees or ponds may be breeding their millions just as these
+and you will only begin to comprehend the meaning of this statement.</p>
+
+<p>As long as these myriads of insects keep in what we are pleased to call
+their proper place we care not for their numbers and think little of
+them except as some student points out some wonderful thing about their
+structure, life-history or adaptations. But since the dawn of history we
+find accounts to show that insects have not always kept to their proper
+sphere but have insisted at various times and in various ways in
+interfering with man's plans and wishes, and on account of their
+excessive numbers the results have often been most disastrous.</p>
+
+<p>Insects cause an annual loss to the people of the United States of over
+$1,000,000,000. Grain fields are devastated; orchards and gardens are
+destroyed or seriously affected; forests are made waste places and in
+scores of other ways these little pests which do not keep in their
+proper places are exacting this tremendous tax from our people.</p>
+
+<p>These things have been known and recognized for centuries, and scores of
+volumes have been written about the insects and their ways and of
+methods of combating them.</p>
+
+<p>But it is only in recent years that we have begun<span class='pagenum'><a name="Page_42" id="Page_42">[Pg 42]</a></span> to realize the really
+important part that insects play in relation to the health of the people
+with whom they are associated. Dr. Howard estimates that the annual
+death rate in the United States from malaria is about twelve thousand,
+entailing an annual monetary loss of about $100,000,000, to say nothing
+of the suffering and misery endured by the afflicted. All this on
+account of two or three species of insects belonging to the mosquito
+genus <i>Anopheles</i>.</p>
+
+<p>Yellow fever, while not so widespread, is more fatal and therefore more
+terrorizing. Its presence and spread are due entirely to a single
+species of mosquito. Flies, fleas, bedbugs, and many other insects have
+been shown to be intimately connected with the spread of several other
+most dreaded diseases, so it is no wonder that physicians, entomologists
+and biologists are studying with utmost zeal many of these forms that
+bear such a close relation not only to our welfare and comfort but to
+our lives as well.</p>
+
+<p>It would be out of place to try to give here even a brief outline of the
+classification of insects, such as may be found in almost any of the
+many books devoted to their study.</p>
+
+<p>The most generally accepted classification divides the insects into
+nineteen orders; as the<span class='pagenum'><a name="Page_43" id="Page_43">[Pg 43]</a></span> Coleoptera, containing the beetles; the
+Lepidoptera, containing the butterflies and moths; the Hymenoptera
+containing the bees, ants and wasps, etc. Four or five of these orders
+will be of more or less interest to us.</p>
+
+<p>The order Diptera, or two-winged flies, is the most important because to
+this belong the mosquitoes which transmit malaria and yellow fever, and
+the house-fly that has come into prominence since it has been found to
+be such an important factor in the distribution of typhoid and other
+diseases.</p>
+
+
+<p class="center">FLIES</p>
+
+<p>The order Diptera is divided into sixty or more families, many of which
+contain species of considerable economic importance. For our present
+consideration the flies may be divided into two groups or sections:
+those with their mouth-parts fitted for piercing such as the mosquito
+and horse-fly, and those with sucking mouth-parts such as the house-fly,
+blow-fly and others.</p>
+
+<p>Some of the species belonging to the first group are among the most
+troublesome pests not only of man but of our domestic animals as well.
+Next to the mosquitoes the horse-flies (<a href="#Fig_22">Fig. 22</a>) are perhaps the best
+known of these. There are several species known under various names,
+such as gad-fly,<span class='pagenum'><a name="Page_44" id="Page_44">[Pg 44]</a></span> breeze-fly, etc. They are very serious pests of horses
+and cattle, sometimes also attacking man. Their strong, sharp, piercing
+stylets enable them to pierce through the toughest skin of animals and
+through the thin clothing of man. The bite is very severe and
+irritating, and as the flies sometimes occur in great numbers the
+annoyance that they cause is often very great indeed. It has often been
+claimed that these flies as well as the stable-fly and others carry the
+anthrax bacillus on their proboscis from one animal to another, and
+although this may not have been definitely proven the evidence is strong
+enough to make a very good case against the accused. It is interesting
+to note in this connection that anthrax, a very common disease among the
+domestic animals and one which may attack man also, was the first
+disease to be shown to be of bacterial origin. It was only about
+thirty-five years ago that the investigations of Koch and Pasteur
+demonstrated that the presence of this particular germ (<i>Bacillus
+anthracis</i>) was the cause of the disease, and it was early recognized
+that such biting flies may be important factors in the spread of the
+disease.</p>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_22" id="Fig_22"></a>
+<img src="images/fig22.jpg" width="250" height="348" alt="Fig. 22" title="" />
+<span class="caption"><span class="smcap">Fig. 22</span>&mdash;Horse-fly (<i>Tabanus punctifer</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_23" id="Fig_23"></a>
+<img src="images/fig23.jpg" width="250" height="254" alt="Fig. 23" title="" />
+<span class="caption"><span class="smcap">Fig. 23</span>&mdash;Stable-fly (<i>Stomoxys calcitrans</i>).</span>
+</div>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 24, 25 and 26">
+<tr>
+ <td class="tdf"><a name="Fig_24" id="Fig_24"></a><img src="images/fig24.jpg" width="200" height="249" alt="Fig. 24" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 24</span></span></td>
+ <td class="tdf"><a name="Fig_25" id="Fig_25"></a><img src="images/fig25.jpg" width="300" height="180" alt="Fig. 25" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 25</span></span></td>
+</tr>
+<tr>
+ <td class="tdf" colspan='2'><a name="Fig_26" id="Fig_26"></a><img src="images/fig26.jpg" width="325" height="361" alt="Fig. 26" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 26</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 24</span>&mdash;A Black-fly (<i>Simulium sp.</i>). (From Kellogg's
+Amer. Insects.)</p>
+<p class="caption2"><span class="smcap">Fig. 25</span>&mdash;Screw-worm fly (<i>Chrysomyia macellaria</i>).</p>
+<p class="caption2"><span class="smcap">Fig. 26</span>&mdash;Blow-fly (<i>Calliphora vomitoria</i>).</p></td>
+</tr>
+</table>
+
+<p><span class='pagenum'><a name="Page_45" id="Page_45">[Pg 45]</a></span></p><p>The stable-fly (<a href="#Fig_23">Fig. 23</a>) (<i>Stomoxys calcitrans</i>) which looks very much
+like the house-fly and, as will be noted later, frequently enters
+houses, is often an important pest of horses and cattle. Its
+blood-sucking habit makes it quite possible that it too may be concerned
+in carrying anthrax and other diseases.</p>
+
+<p>In a later chapter it will be shown how the tsetse-fly, which is
+somewhat like the stable-fly, is responsible for the spread of the
+disease known as the sleeping sickness. This disease is caused by a
+Protozoan parasite, a trypanosome, which is transmitted from one host to
+another by the tsetse-fly.</p>
+
+<p>In Southern Asia and in parts of Africa there is a very serious disease
+of horses known as surra which is caused by a similar parasite
+(<i>Trypanosoma evansi</i>). This parasite attacks horses, mules, camels,
+elephants, buffaloes and dogs, and has been recently imported into the
+Philippines. It is supposed that flies belonging to the same genus as
+the horse-fly (<i>Tabanus</i> and others), and the stable-fly (<i>Stomoxys</i>)
+and the horn-fly (<i>H&aelig;matobia</i>) are responsible for the spread of the
+disease.</p>
+
+<p>Nagana is one of the most serious diseases of domestic animals in
+Central and Southern Africa. In some sections it is almost impossible to
+keep any kind of imported animals on account of this disease which is
+caused by a parasite (<i>Trypanosoma brucei</i>) similar to the one causing
+surra. This<span class='pagenum'><a name="Page_46" id="Page_46">[Pg 46]</a></span> parasite is to be found in several different kinds of
+native animals which seem to be practically immune but are always a
+source of danger when other animals are introduced. Two or three species
+of tsetse-flies are responsible for the transmission of this disease.</p>
+
+<p>Another group of flies much smaller but more numerous and much more
+insistent are the black-flies or buffalo-gnats (<a href="#Fig_24">Fig. 24</a>). For more than
+a century these little flies have been recognized as among the most
+serious pests of stock, particularly in the south where, besides the
+actual loss by death of many animals yearly, the annoyance is so great
+as to sometimes make it impossible to work in the field. Human beings
+are often attacked, and as the bite is poisonous and very painful great
+suffering may result and cases of deaths from such bites have been
+reported.</p>
+
+<p>Belonging to another family, and smaller, but much like the buffalo-gnat
+in habits, are the minute little "punkies" or "no-see-ums" which
+sometimes occur in great swarms in certain regions where they make life
+a burden to man and beast. While it has not been shown that either the
+buffalo-gnats or the punkies are responsible for the transmission of any
+disease, their habits of feeding on so many different kinds of wild and
+domestic animals as<span class='pagenum'><a name="Page_47" id="Page_47">[Pg 47]</a></span> well as on man makes it possible for them to act as
+carriers of parasites that might under proper conditions become of
+serious importance. Then, too, the irritation caused by the bites of
+these insects usually causes scratching which may result in abrasions of
+the skin that open the way for various harmful germs, particularly those
+causing skin diseases.</p>
+
+<p>Coming now to the group containing the house-flies and related forms we
+find a number that are of interest on account of the suffering that they
+may cause, particularly in their larval stages.</p>
+
+<p>The screw-worm flies (<i>Chrysomyia macellaria</i>) are among the most common
+and important of these (<a href="#Fig_25">Fig. 25</a>). These "gray flies," as they are
+sometimes called, lay a mass of three or four hundred eggs on the
+surface of wounds. The larv&aelig; which in a few hours hatch from these make
+their way directly into the wound where they feed on the surrounding
+tissue until full grown when they wriggle out and drop to the ground
+where they transform to the pupa and later to the adult fly. Of course
+their presence in the wounds is very distressing to the infected animal,
+and great suffering results. Slight scratches that might otherwise
+quickly heal often become serious sores because of the presence of these
+larv&aelig;.</p>
+
+<p><span class='pagenum'><a name="Page_48" id="Page_48">[Pg 48]</a></span></p><p>Many cases are recorded of these flies laying their eggs in the ears or
+nose of children or of persons sleeping out of doors during the day.
+Especially is this apt to occur if there are offensive discharges which
+attract the fly. In such cases the larv&aelig; burrow into the surrounding
+tissues, devouring the mucous membranes, the muscles and even the bones,
+causing terrible suffering and usually, death. The larv&aelig; in such
+situations may be killed with chloroform and, if the case is attended to
+before they have destroyed too much of the tissues, recovery usually
+occurs.</p>
+
+<p>The blow-flies (<a href="#Fig_26">Fig. 26</a>) (<i>Calliphora vomitoria</i>) and the blue-bottle
+flies (<a href="#Fig_27">Fig. 27</a>), (<i>Lucilia spp.</i>) and the flesh-flies (<a href="#Fig_28">Fig. 28</a>)
+(<i>Sarcophaga spp.</i>) all have habits somewhat like the screw-worm fly.
+Any of them may lay their eggs in wounds on man or animals with the same
+serious results.</p>
+
+<p>The flesh-fly instead of laying eggs deposits the living larv&aelig; upon meat
+wherever it is accessible, and as these develop with astonishing
+rapidity they are able to consume large quantities of flesh in a
+remarkably short time. In this way they may be of some importance as
+scavengers, but it is better to get rid of the waste in other ways than
+to leave it for a breeding-place for flies that are capable of causing
+so much damage and suffering.</p>
+
+<p><span class='pagenum'><a name="Page_49" id="Page_49">[Pg 49]</a></span></p><p>Not infrequently the larv&aelig; of certain flies are to be found in the
+alimentary canal where as a rule they do no particular damage.
+Altogether the larv&aelig; of over twenty different species of flies have been
+found in or expelled from the human intestinal canal. In Europe, the
+majority of these larv&aelig; belong to a fly which looks very much like the
+house-fly except that it is somewhat smaller and so is often known as
+"the little house-fly" (<a href="#Fig_29">Fig. 29</a>) (<i>Homalomyia canicularis</i>). The same
+species is very common in the United States, frequently occurring in
+houses. Under certain conditions it may even be more abundant than the
+house-fly. It is believed that the larv&aelig; in the intestinal canal come
+from eggs that have been deposited on the victim while using an outdoor
+privy where the flies are often very abundant. Instances are also on
+record where these larv&aelig; have been discharged from the urethra.</p>
+
+<p>Another fly (<i>Ochromyia anthropophaga</i>) occurring in the Congo region
+has a blood-sucking larv&aelig; which is known as the Congo floor-maggot. The
+fly which is itself not troublesome deposits its eggs in the cracks and
+crevices of the mud floors of the huts. The larv&aelig; which hatch from these
+crawl out at night and suck the blood of the victim that may be sleeping
+on the floor or on a low bed.</p>
+
+
+<p><span class='pagenum'><a name="Page_50" id="Page_50">[Pg 50]</a></span></p><p class="center">BOT-FLIES</p>
+
+<p>Another group of flies known as the bot-flies (<a href="#Fig_30">Fig. 30</a>) have their
+mouth-parts rudimentary or entirely wanting so of course they themselves
+cannot bite or pierce an animal. Nevertheless they are the source of an
+endless amount of trouble to stockmen and sometimes even attack man.
+Although these flies cannot bite, the presence of even a single
+individual may be enough to annoy a horse almost to the end of
+endurance. Horses seem to have an instinctive fear of them and will do
+all in their power to get rid of the annoying pests.</p>
+
+<p>The eggs of the house bot-fly are laid on the hair of the legs or some
+other part of the body. The horse licks them off and they hatch and
+develop in the alimentary canal of their host. Sometimes the walls of
+the stomach may be almost covered with them thus of course seriously
+interfering with the functions of this organ. When full grown the larv&aelig;
+pass from the host and complete their transformation in the ground.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_27" id="Fig_27"></a>
+<img src="images/fig27.jpg" width="350" height="347" alt="Fig. 27" title="" />
+<span class="caption"><span class="smcap">Fig. 27</span>&mdash;Blue-bottle fly (<i>Lucilia sericata</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_28" id="Fig_28"></a>
+<img src="images/fig28.jpg" width="350" height="314" alt="Fig. 28" title="" />
+<span class="caption"><span class="smcap">Fig. 28</span>&mdash;Flesh-fly (<i>Sarcophaga sp</i>).</span>
+</div>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 29-32">
+<tr>
+ <td class="tdf"><a name="Fig_29" id="Fig_29"></a><img src="images/fig29.jpg" width="250" height="223" alt="Fig. 29" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 29</span>&mdash;"The little house-fly" (<i>Homalomyia canicularis</i>).</span></td>
+ <td class="tdf"><a name="Fig_30" id="Fig_30"></a><img src="images/fig30.jpg" width="250" height="249" alt="Fig. 30" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 30</span>&mdash;Horse bot-fly (<i>Gastrophilus equi</i>)</span></td>
+</tr>
+<tr>
+ <td class="tdf"><a name="Fig_31" id="Fig_31"></a><img src="images/fig31.jpg" width="250" height="249" alt="Fig. 31" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 31</span>&mdash;Ox warble-fly (<i>Hypoderma lineata</i>).</span></td>
+ <td class="tdf"><a name="Fig_32" id="Fig_32"></a><img src="images/fig32.jpg" width="250" height="240" alt="Fig. 32" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 32</span>&mdash;Sheep bot-fly (<i>Gastrophilus nasalis</i>).</span></td>
+</tr>
+</table>
+
+<p><span class='pagenum'><a name="Page_51" id="Page_51">[Pg 51]</a></span></p><p>The bot-flies of cattle or the oxwarbles (<a href="#Fig_31">Fig. 31</a>) gain an entrance
+into the alimentary canal in the same way, that is, by the eggs being
+licked from the hairs on the body where they have been laid by the adult
+fly. But instead of passing on into the stomach they collect in the
+esophagus and later make their way through the walls of this organ and
+through the tissues of the body until they at last reach a place along
+the back just under the skin. Here as they are completing their
+development they make more or less serious sores on the backs of the
+infested animals. The hides on such animals are rendered nearly
+valueless by the holes made by the larv&aelig;. When fully mature they drop to
+the ground and complete their transformations.</p>
+
+<p>The sheep bot-flies (<a href="#Fig_32">Fig. 32</a>) lay their eggs in the nostrils of sheep.
+The larv&aelig; pass up into the frontal sinuses where they feed on the mucus,
+causing great suffering and loss. Many other species of animals are
+infested with their own particular species of bots. Several instances
+are recorded where the oxwarble has occurred in man, always causing much
+suffering and sometimes death.</p>
+
+<p>One or more species of bot-flies occurring in the tropical parts of
+America frequently attack man. The early larval stage soon after it has
+entered the skin is known as the <i>Ver macaque</i>. Later stages as <i>torcel</i>
+or <i>Berne</i>. The presence of the larv&aelig; produces very painful and
+troublesome sores. It is supposed that the adult flies (one species of
+which is <i>Dermatobia cyaniventris</i>) lay their eggs on the<span class='pagenum'><a name="Page_52" id="Page_52">[Pg 52]</a></span> skin which
+the larv&aelig; penetrate as soon as they hatch. It has also been suggested
+that they might reach the subcutaneous tissue by migrating from the
+alimentary canal as do some of the other bot-flies. A very serious eye
+disease, <i>Egyptian opthalmia</i>, is known to be spread by the house-flies
+and others. These flies are often abundant about the eyes, especially of
+children suffering from this disease. It is suspected that certain small
+flies (Oscinid&aelig;) in the southern part of the United States are
+responsible for the spread of disease known as "sore eye."</p>
+
+
+<p class="center">FLEAS</p>
+
+<p>The fleas used to be considered as degenerate Diptera and were placed
+with that group but they are now classed as a separate order
+(Siphonaptera). Within recent years these little pests have come into
+special prominence on account of their importance in connection with the
+spread of the plague. The fact that they are so abundant everywhere and
+that they will so readily pass from one host to another makes the
+possibility of their spreading infectious diseases very great. Besides
+the kinds that are concerned in the transmission of plague, which are
+discussed in another chapter, there are many other kinds infesting
+various<span class='pagenum'><a name="Page_53" id="Page_53">[Pg 53]</a></span> wild and domesticated animals and a few attacking birds.</p>
+
+<p>One of the most important of these is the jigger-flea or chigoe
+(<i>Dermatophilus penetrans</i>, <a href="#Fig_33">Fig. 33</a>). Various other names such as
+chigger-flea, sand-flea, jigger, chigger are also applied to this insect
+as well as to a minute red mite that burrows into the skin in much the
+same way as the female of the flea. So although they are entirely
+different creatures you can never tell from the common name, whether it
+is the flea or the mite that is being referred to. Both the male and
+female jigger-fleas feed on the host and hop on or off as do other
+fleas, but when the female is ready to lay eggs (<a href="#Fig_34">Fig. 34</a>), she burrows
+into the skin. Her presence there causes a swelling and usually an ulcer
+which often becomes very serious, especially if the insect should be
+crushed and the contents of the body escape into the surrounding tissue.</p>
+
+<p>These little pests are found throughout tropical and subtropical America
+and have been introduced into Africa and from there have spread to India
+and elsewhere. They attack almost all kinds of animals as well as many
+birds, being of course a source of great annoyance and no inconsiderable
+loss. They are more apt to attack the feet of men, especially those who
+go barefooted. Sometimes<span class='pagenum'><a name="Page_54" id="Page_54">[Pg 54]</a></span> they occur in such numbers as to make great
+masses of sores.</p>
+
+<p>On account of being such general feeders they are difficult to control,
+but some relief may be obtained by keeping the houses and barns as free
+as possible from dirt and rubbish and by sprinkling the breeding-places
+of the pest with pyrethrum powder or carbolic water. Those that gain an
+entrance into the skin should be cut out, care being taken to remove the
+insect entire.</p>
+
+
+<p class="center">BEDBUGS</p>
+
+<p>In the order Hemiptera, or the true "bugs" in an entomological sense, we
+find a few forms that may carry disease. The bedbug (<a href="#Fig_35">Fig. 35</a>) (<i>Cimex
+lectularis</i>) has been accused of transmitting plague, relapsing fever
+and other diseases. Very recent investigations show that the common
+bedbug of India (<i>Cimex rotundatus</i>) harbors the parasite that causes
+the disease known as <i>kala azar</i>, and there is no doubt that it
+transmits the disease.</p>
+
+
+<p class="center">LICE</p>
+
+<p>The sucking lice (<a href="#Fig_36">Fig. 36</a>) which also belong to this order are suspected
+of carrying some of these same diseases. It is thought that the common
+louse on rats (<i>H&aelig;matopinus spinulosus</i>) is responsible for the spread
+from rat to rat of a certain parasite. (<i>Trypanosoma lewisi</i>), which,
+however, does not produce any disease in the rats, but if they are
+capable of acting as alternative hosts for such parasites, it is quite
+possible that they may also carry disease-producing forms.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_33" id="Fig_33"></a>
+<img src="images/fig33.jpg" width="350" height="285" alt="Fig. 33" title="" />
+<span class="caption"><span class="smcap">Fig. 33</span>&mdash;Chigo or jigger-flea, male (<i>Dermatophilus
+penetrans</i>). (After Karsten.)</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_34" id="Fig_34"></a>
+<img src="images/fig34.jpg" width="350" height="276" alt="Fig. 34" title="" />
+<span class="caption"><span class="smcap">Fig. 34</span>&mdash;Chigo, female distended with eggs. (After Karsten.)</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_35" id="Fig_35"></a>
+<img src="images/fig35.jpg" width="350" height="385" alt="Fig. 35" title="" />
+<span class="caption"><span class="smcap">Fig. 35</span>&mdash;Bedbug (<i>Cimex lectularis</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_36" id="Fig_36"></a>
+<img src="images/fig36.jpg" width="350" height="478" alt="Fig. 36" title="" />
+<span class="caption"><span class="smcap">Fig. 36</span>&mdash;Body-louse (<i>Pediculus vestimenti</i>). (From
+drawing by J.H. Paine.)</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_55" id="Page_55">[Pg 55]</a></span></p><p class="center">HOW INSECTS MAY CARRY DISEASE GERMS</p>
+
+<p>Insects may carry the germs or parasites which cause disease in a purely
+mechanical or accidental way, that is, the insect may in the course of
+its wanderings or its feeding get some of the germs on or in its body
+and may by chance carry these to the food, or water, or directly to some
+person who may become infected. Thus the house-fly may carry the typhoid
+germs on its feet or in its body and distribute them in places where
+they may enter the human body.</p>
+
+<p>Several other flies as well as fleas, bedbugs, ticks, etc., may also
+carry disease germs in this mechanical way. While this method of
+transmission is just as dangerous as any other, and possibly more
+dangerous because more common, another method in which the insect is
+much more intimately concerned is more interesting from a biological
+standpoint at least and will be discussed<span class='pagenum'><a name="Page_56" id="Page_56">[Pg 56]</a></span> more fully in the chapters on
+malaria, yellow fever and elephantiasis.</p>
+
+<p>In these cases the insect is one of the necessary hosts of the parasite,
+which cannot go on with its development or pass from one patient to
+another unless it first enters the insect at a certain stage of its
+life-history.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_37" id="Fig_37"></a>
+<img src="images/fig37.jpg" width="450" height="401" alt="Fig. 37" title="" />
+<span class="caption"><span class="smcap">Fig. 37</span>&mdash;One use for the house-fly.</span>
+</div>
+
+<p class="center">BABY-BYE.</p>
+
+<p class="poem">
+1. Baby-Bye,<br />
+Here's a fly;<br />
+We will watch him, you and I.<br />
+<span style="margin-left: 1em;">How he crawls</span><br />
+<span style="margin-left: 1em;">Up the walls,</span><br />
+<span style="margin-left: 1em;">Yet he never falls!</span><br />
+I believe with six such legs<br />
+You and I could walk on eggs.<br />
+<span style="margin-left: 1em;">There he goes</span><br />
+<span style="margin-left: 1em;">On his toes,</span><br />
+<span style="margin-left: 1em;">Tickling Baby's nose.</span><br />
+</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_57" id="Page_57">[Pg 57]</a></span></p>
+<h2><a name="CHAPTER_V" id="CHAPTER_V"></a>CHAPTER V</h2>
+
+<h3>HOUSE-FLIES OR TYPHOID-FLIES</h3>
+
+<div class="figdrop">
+<img src="images/dropt.jpg" width="75" height="77" alt="dropt" title="" />
+</div>
+<p class="noin"><span class="caps">he</span> page shown in <a href="#Fig_37">Fig. 37</a> was copied from one of our old second readers
+and shows something of the spirit in which we used to regard the
+house-fly. A few of them were nice things to have around to make things
+seem "homelike." Of course they sometimes became too friendly during the
+early morning hours when we were trying to take just one more little nap
+or they were sometimes too insistent for their portion of the dinner
+after it had been placed on the table, but a screen over the bed would
+help us out a little in the morning and a long fly-brush cut from a tree
+in the yard or made of strips of paper tacked to a stick or, still more
+fancy, made of long peacock plumes, would help to drive them from the
+table. Those that were knocked into the coffee or the cream could be
+fished out; those that went into the soup or the hash were never missed!</p>
+
+<p>Not only were the flies regarded as splendid things with which to amuse
+the baby, but they<span class='pagenum'><a name="Page_58" id="Page_58">[Pg 58]</a></span> were thought to be very useful as scavengers as they
+were often seen feeding on all kinds of refuse in the yard. Then, too,
+they seemed to be cleanly little things, for almost any time some of
+them could be seen brushing their heads and bodies with their legs and
+evidently having a good clean-up. More than that it never occurred to us
+that it would be possible to get rid of them even should it be thought
+advisable, for they came from "out doors," and who could kill all the
+flies "out doors"?</p>
+
+<p>Fortunately, or otherwise, these halcyon days have gone by and the
+common, innocent, friendly little house-fly is now an outcast convicted
+of many crimes and accused of a long list of others (<a href="#Fig_38">Fig. 38</a>).</p>
+
+<p>Its former friends have become its sworn enemies. The foremost
+entomologist of the land has suggested that we even change its name and
+give it one that would be more suggestive of the abhorence with which we
+now look upon it.</p>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_38" id="Fig_38"></a>
+<img src="images/fig38.jpg" width="450" height="573" alt="Fig. 38" title="" />
+<span class="caption"><span class="smcap">Fig. 38</span>&mdash;The house-fly (<i>Musca domestica</i>).</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_59" id="Page_59">[Pg 59]</a></span></p><p>And all these changes have come about because science has turned the
+microscope on the house-fly and men have studied its habits. We know now
+that as the fly is "tickling baby's nose" it may be spreading there
+where they may be inhaled or where they may be taken into the baby's
+mouth thousands of germs some of which may cause some serious disease.
+We know that as they are buzzing about our faces while we are trying to
+sleep they may, unwittingly, be in the same nefarious business, and we
+know that as they sip from our cups with us or bathe in our coffee or
+our soup or walk daintily over our beefsteak or frosted cake they are
+leaving behind a trail of filth and bacteria, and we know that some of
+these germs may be and often are the cause of some of our common
+diseases. As the typhoid germs are very often distributed in this way,
+Dr. Howard has suggested that the house-fly shall be known in the future
+as the typhoid-fly, not because it is solely responsible for the spread
+of typhoid, but because it is such an important factor in it and is so
+dangerous from every point of view. The names "manure fly" and "privy
+fly" have also been suggested and would perhaps serve just as well, as
+the only object in giving it another name would be to find a more
+repulsive one to remind us constantly of the filthy and dangerous habits
+of the fly.</p>
+
+
+<p class="center">STRUCTURE</p>
+
+<p>In order that we may better understand why it is that the house-fly is
+capable of so much mischief, let us consider briefly a few points in<span class='pagenum'><a name="Page_60" id="Page_60">[Pg 60]</a></span>
+regard to its structure, its methods of feeding and its life-history.</p>
+
+<p>The large compound eyes are the most conspicuous part of the head (<a href="#Fig_39">Fig.
+39</a>). In front, between the eyes, are the three-jointed antenn&aelig;, the last
+joint bearing a short, feathery bristle. From the under side of the head
+arises the long, fleshy proboscis (<a href="#Fig_40">Fig. 40</a>). When this is fully extended
+it is somewhat longer than the head; when not distended and in use it is
+doubled back in the cavity on the under side of the head. About half-way
+between the base and the middle is a pair of unjointed mouth-feelers
+(maxillary palpi). At the tip are two membranous lobes (<a href="#Fig_41">Fig. 41</a>) closely
+united along their middle line. These are covered with many fine
+corrugated ridges, which under the microscope look like fine spirals and
+are known as pseudotrache&aelig;. Thus it will be seen that the house-fly's
+mouth-parts are fitted for sucking and not for biting. Its food must be
+in a liquid or semi-liquid state before it can be sucked through the
+tube leading from the lobes at the tip up through the proboscis and on
+into the stomach. If the fly wishes to feed on any substance such as
+sugar, that is not liquid, it first pours out some saliva on it and then
+begins to rasp it with the rough terminal lobes of the proboscis, thus
+reducing the food to a consistency that will enable the fly to suck it
+up. Many people think that house-flies can bite and will tell you that
+they have been bitten by them. But a careful examination of the
+offender, in such instances, will show that it was not a house-fly but
+probably a stable-fly, which does have mouth-parts fitted for piercing.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_39" id="Fig_39"></a>
+<img src="images/fig39.jpg" width="300" height="519" alt="Fig. 39" title="" />
+<span class="caption"><span class="smcap">Fig. 39</span>&mdash;Head of house-fly showing eyes, antenn&aelig; and mouth-parts.</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_40" id="Fig_40"></a>
+<img src="images/fig40.jpg" width="250" height="259" alt="Fig. 40" title="" />
+<span class="caption"><span class="smcap">Fig. 40</span>&mdash;Proboscis of house-fly, side view.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_41" id="Fig_41"></a>
+<img src="images/fig41.jpg" width="400" height="372" alt="Fig. 41" title="" />
+<span class="caption"><span class="smcap">Fig. 41</span>&mdash;Lobes at end of proboscis of house-fly showing corrugated ridges.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_42" id="Fig_42"></a>
+<img src="images/fig42.jpg" width="400" height="196" alt="Fig. 42" title="" />
+<span class="caption"><span class="smcap">Fig. 42</span>&mdash;Wing of house-fly.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_61" id="Page_61">[Pg 61]</a></span></p><p>The thorax bears the two rather broad, membranous wings (<a href="#Fig_42">Fig. 42</a>) which
+have characteristic venation. Three of these veins end rather close
+together just before the tip of the wing, the posterior one of the group
+being bent forward rather sharply a short distance from the tip. The
+stable-fly has this vein slightly curved forward but not nearly so
+conspicuously (<a href="#Fig_43">Fig. 43</a>).</p>
+
+<p>Nearly all the other flies that are apt to be mistaken for the house-fly
+do not have this vein curved forward. The wings, although apparently
+bare, are covered with a fine microscopic pubescence. Among these fine
+hairs on the wing as well as among similar fine ones and coarser ones
+all over the body, particles of dust and dirt or filth (<a href="#Fig_44">Fig. 44</a>) or,
+what interests us more just now, thousands of germs may find a temporary
+lodgment and later be scattered through the air as the insect flies. Or
+they may get on our food as the<span class='pagenum'><a name="Page_62" id="Page_62">[Pg 62]</a></span> fly feeds or while it rests and combs
+its body with the rows of coarse hairs on its legs.</p>
+
+<p>The legs are rather thickly covered with coarse hairs or bristles and
+with a mat of fine, short hairs. On some of the segments the larger
+hairs are arranged in rows and are used as a sort of comb with which the
+fly combs the dirt from the rest of its body. The last segment (<a href="#Fig_45">Fig. 45</a>)
+of the leg bears at its tip a pair of large curved claws and a pair of
+membranous pads known as the pulvill&aelig;. On the under side of the pulvill&aelig;
+are innumerable minute secreting hairs (<a href="#Fig_46">Fig. 46</a>) by means of which the
+fly is able to walk on the wall or ceiling or in any position on
+highly-polished surfaces.</p>
+
+
+<p class="center">HOW THEY CARRY BACTERIA</p>
+
+<p>These same little pads, with their covering of secreting hairs, are
+perhaps the most dangerous part of the insect for they cannot help but
+carry much of the filth over or through which the fly walks, and as this
+may be well stocked with germs the danger is at once apparent.</p>
+
+<p>As the result of a series of carefully planned experiments it has been
+demonstrated that the number of bacteria on a single fly may range all
+the way from 550 to 6,600,000 with an average for the lot experimented
+with of about one and one-fourth million bacteria to each fly. Now where
+do all these bacteria come from? Necessarily from the place where the
+fly breeds or where it feeds.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_43" id="Fig_43"></a>
+<img src="images/fig43.jpg" width="400" height="196" alt="Fig. 43" title="" />
+<span class="caption"><span class="smcap">Fig. 43</span>&mdash;Wing of Stable-fly (<i>Stomoxys calcitrans</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_44" id="Fig_44"></a>
+<img src="images/fig44.jpg" width="400" height="200" alt="Fig. 44" title="" />
+<span class="caption"><span class="smcap">Fig. 44</span>&mdash;Wing of house-fly showing particles of dirt adhering to it.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_45" id="Fig_45"></a>
+<img src="images/fig45.jpg" width="400" height="221" alt="Fig. 45" title="" />
+<span class="caption"><span class="smcap">Fig. 45</span>&mdash;Last three segments of leg of house-fly showing
+the claws, the pulvill&aelig; and the hairs on the legs.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_46" id="Fig_46"></a>
+<img src="images/fig46.jpg" width="400" height="406" alt="Fig. 46" title="" />
+<span class="caption"><span class="smcap">Fig. 46</span>&mdash;Foot of house-fly showing claws, hairs,
+pulvill&aelig; and the minute clinging hairs on the pulvill&aelig;.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_47" id="Fig_47"></a>
+<img src="images/fig47.jpg" width="400" height="235" alt="Fig. 47" title="" />
+<span class="caption"><span class="smcap">Fig. 47</span>&mdash;Larva of house-fly.</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_63" id="Page_63">[Pg 63]</a></span></p><p class="center">LIFE-HISTORY AND HABITS</p>
+
+<p>The eggs of the house-fly may be laid on almost any kind of decaying or
+fermenting material. If this is kept moist and a proper temperature
+maintained the larv&aelig; or maggots (<a href="#Fig_47">Fig. 47</a>) that hatch from the eggs may
+develop. As a rule, however, these requirements are found only under
+certain conditions and are ordinarily found only in manure heaps or in
+privy vaults or latrines. All observers agree that the female fly
+prefers to deposit her eggs in horse manure when this can be found and
+when this is piled in heaps in the barn-yard (<a href="#Fig_48">Fig. 48</a>) or in the field
+the heat caused by the decay and fermentation makes ideal conditions for
+the development of the larv&aelig;. Cow manure may serve as a breeding-place
+to a limited extent. The flies are immediately attracted to human
+excrement and breed freely in it when opportunity offers. Decaying
+vegetables or fruit, fermenting kitchen refuse and other materials
+sometimes also serve as breeding-places.</p>
+
+<p>In suitable places in warm weather the eggs will<span class='pagenum'><a name="Page_64" id="Page_64">[Pg 64]</a></span> hatch in from eight to
+twelve hours and the larv&aelig; will become fully developed in from eight to
+fourteen days. They then change to pup&aelig; (<a href="#Fig_50">Fig. 50</a>) in which stage they
+may remain for another eight to twenty days when the adult flies will
+emerge. These figures must necessarily be indefinite because the weather
+and other conditions always vary. Under the most favorable conditions of
+moisture and temperature it is probably never less than eight days from
+egg to adult fly and under unfavorable conditions it may be as long as
+six weeks.</p>
+
+<p>The larv&aelig; thrive best when the manure is kept quite wet. I have often
+found them in almost incredible numbers in stables that had not been
+cleaned for some time. The horses standing there at night added fresh
+material and kept it just wet enough to make conditions almost ideal
+(<a href="#Fig_49">Fig. 49</a>).</p>
+
+<p>The pup&aelig; are usually found where the manure is a little dryer, but it
+must not be too dry. When the flies issue from the pup&aelig; they push their
+way up to the surface where they remain for a short time and allow the
+body to harden and the wings to dry before they fly away to other manure
+or, as too often happens, to some near-by kitchen or restaurant or
+market place.</p>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_48" id="Fig_48"></a>
+<img src="images/fig48.jpg" width="500" height="327" alt="Fig. 48" title="" />
+<span class="caption"><span class="smcap">Fig. 48</span>&mdash;Barn-yard filled with manure. Millions of flies
+were breeding here and infesting all the near-by houses.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_49" id="Fig_49"></a>
+<img src="images/fig49.jpg" width="500" height="314" alt="Fig. 49" title="" />
+<span class="caption"><span class="smcap">Fig. 49</span>&mdash;Dirty stalls; the manure had not been removed
+for some days and the floor was covered with maggots.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_65" id="Page_65">[Pg 65]</a></span></p><p>Of course it is impossible for them to issue from this filth without
+more or less of it clinging to their bodies. Now if these flies would
+breed only in barn-yard manure and fly directly from the stable to the
+house there would be comparatively little reason to complain, at least
+from a sanitary standpoint, for the amount of barn-yard filth that they
+carried to our food would be of little consequence. But when they breed
+in privy vaults or similar places, or visit such places before coming
+into the house or dairy or market place the results may be much more
+serious.</p>
+
+
+<p class="center">FLIES AND TYPHOID</p>
+
+<p>It has been abundantly demonstrated that the excrement or the urine of a
+typhoid patient may contain virulent germs for some time before he is
+aware that he has the disease, and it has been shown that the germs may
+be present for weeks or months, and in some cases even years after the
+patient has recovered. If a fly breeds in such infected material, or
+feeds or walks on it, it is very apt to get some of the germs on its
+body where they may retain their virulence for some time, and should it
+visit our food while covered with these germs some of them would
+probably be left there where they might produce serious results. More
+than that. If the fly should feed on such infected material the<span class='pagenum'><a name="Page_66" id="Page_66">[Pg 66]</a></span> typhoid
+germs would go on developing in the intestine of the fly and would be
+passed out with the feces in which they retain their virulence for some
+days. In other words, the too familiar "fly-specks" are not only
+disgusting, but may be a very grave source of danger. It will be seen
+that in this way several members of a community might become infected
+with the typhoid germs before anyone was aware that there was a case of
+typhoid or a "bacillus carrier" in the neighborhood.</p>
+
+<p>One more example out of the scores that might be cited to show how the
+fly may carry typhoid germs. They may enter the sick chamber in the home
+or in the hospital and there gain access to the typhoid germs. These
+they may carry to other parts of the house or to near-by houses, or the
+flies may light on passing carriages or cars and be carried perhaps for
+miles before they enter another house and contaminate the food there.</p>
+
+<p>These are hypothetical cases, but they illustrate what is taking place
+hundreds of times every season all over the world wherever typhoid fever
+and flies occur, and no country or race is known to be immune from
+typhoid, and the fly is found "wherever man is found."</p>
+
+<p>In the summer of 1898 a commission was appointed to investigate the
+prevalence of typhoid<span class='pagenum'><a name="Page_67" id="Page_67">[Pg 67]</a></span> fever in the United States Army Concentration
+Camps. The following are some of the conclusions as reported by Dr.
+Vaughan:</p>
+
+<div class="blockquot"><p class="center">"FLIES UNDOUBTEDLY SERVED AS CARRIERS OF THE INFECTION</p>
+
+<p>"My reasons for believing that flies were active in the
+dissemination of typhoid may be stated as follows:</p>
+
+<p>"<i>a.</i> Flies swarmed over infected fecal matter in the pits and then
+visited and fed upon the food prepared for the soldiers at the mess
+tents. In some instances where lime had recently been sprinkled
+over the contents of the pits, flies with their feet whitened with
+lime were seen walking over the food.</p>
+
+<p>"<i>b.</i> Officers whose mess tents were protected by means of screens
+suffered proportionately less from typhoid fever than did those
+whose tents were not so protected.</p>
+
+<p>"<i>c.</i> Typhoid fever gradually disappeared in the fall of 1898, with
+the approach of cold weather, and the consequent disabling of the
+fly.</p>
+
+<p>"It is possible for the fly to carry the typhoid bacillus in two
+ways. In the first place, fecal matter containing the typhoid germ
+may adhere to the fly and be mechanically transported. In the
+second place, it is possible that the typhoid bacillus may be
+carried in the digestive organs of the fly and may be deposited
+with its excrement." </p></div>
+
+<p>In Dr. Daniel D. Jackson's report to the Merchants' Association of New
+York on the "Pollution<span class='pagenum'><a name="Page_68" id="Page_68">[Pg 68]</a></span> of New York Harbor as a Menace to the Health by
+the Dissemination of Intestinal Diseases Through the Agency of the
+Common House-fly," he shows graphically that the prevalence of typhoid
+and other intestinal diseases is coincident with the prevalence of
+flies, and that the greatest number of deaths from such diseases occurs
+near the river front where the open or poorly constructed sewers scatter
+the filth where the flies can feed on it, or along the wharves with
+their inadequate accommodations and the resulting accumulation of filth.</p>
+
+
+<p class="center">FLIES AND OTHER DISEASES</p>
+
+<p>Not only is the house-fly an important factor in the dissemination of
+typhoid fever, but it has been definitely shown that it is capable of
+transmitting several other serious diseases.</p>
+
+<p>The evidence that flies carry and spread the deadly germs of cholera is
+most conclusive. The germs may be carried on the body where they will
+live but a short time, or they may be carried in the alimentary canal
+where they will live for a much longer period and are finally deposited
+in the fly-specks where they retain their virulence for some time. Flies
+that had been allowed to contaminate themselves with cholera germs were
+allowed access to milk and meat. In both cases hundreds of<span class='pagenum'><a name="Page_69" id="Page_69">[Pg 69]</a></span> colonies of
+the germs could later be recovered from the food. As with the typhoid
+germs milk seems to be a particularly good medium for the development of
+the cholera germs. In several of the experiments that have been made
+along this line the milk has been readily infected by the flies visiting
+it.</p>
+
+<p>Of course an outbreak of cholera is of rare occurrence in our country,
+but unfortunately this is not so in regard to some other intestinal
+diseases such as diarrhea and enteritis which annually cause the death
+of many children, especially bottle-fed babies. Those who have made
+close studies of the way in which these diseases are disseminated are
+convinced that the flies are one of the most important factors in their
+spread.</p>
+
+<p>It has long been observed that flies are particularly fond of sputum and
+will feed on it on the sidewalk, in the gutter, the cuspidor or wherever
+opportunity offers. It is well known, too, that the sputum of a
+consumptive contains myriads of virulent tubercular germs. A fly feeding
+and crawling over such material must necessarily get some of it on its
+body, and as it dries and the insect flies about the germs will be
+distributed through the air, possibly over our food. It has been shown
+that the excretion from a fly that has fed on tubercular sputum contains
+tubercular bacilli that may<span class='pagenum'><a name="Page_70" id="Page_70">[Pg 70]</a></span> remain virulent for at least fifteen days.
+Thus we see again the danger that may lurk in the too familiar
+"fly-specks."</p>
+
+<p>Although it is generally supposed that the flea is solely responsible
+for the spread of the bubonic plague and no doubt is the principal
+distributing agent, the fact must not be overlooked that the house-fly
+may also be of considerable importance in this connection. Carefully
+planned experiments have shown that flies that have become infected by
+being fed on plague-infected material may carry the germs for several
+days and that they may die of the disease. During plague epidemics flies
+may become infected by visiting the sores on human or rat victims or by
+feeding on dead rats or on the excreta of sick patients, and an infected
+fly is always a menace should it visit our food or open wounds or sores.
+Anthrax bacilli are carried about and deposited by flies showing the
+possibility of the disease being spread in this way.</p>
+
+<p>Some believe that leprosy, smallpox and many other diseases are carried
+by the house-fly, so it is little wonder that it is fast losing its
+standing as a household companion and that we are beginning to regard it
+not only as a nuisance but as a source of danger which should no longer
+be tolerated in any community.</p>
+
+<p><span class='pagenum'><a name="Page_71" id="Page_71">[Pg 71]</a></span></p><p>Of course only a small per cent of the flies that visit our food in the
+dairies or market places or kitchens actually carry dangerous diseases,
+but they are all bred in filth and it is not possible without careful
+experiments or laboratory analysis to determine whether any of the germs
+among the millions that are on their bodies are dangerous or not. The
+chances that they may be are too great. The only safe way is to banish
+them all or to see that all of our food is protected from them.</p>
+
+
+<p class="center">FIGHTING FLIES</p>
+
+<p>Screens and sticky fly-paper have their places and give some little
+relief in a well-kept house. But of what use is it to protect your food
+after it has entered your home if in the stores, in the market place, in
+the dairy barn, or dairy wagon, in the grocers' and butchers' cart, it
+has been exposed to contamination by hundreds of flies that have visited
+it.</p>
+
+<p>The problem is a larger one than keeping the house free from flies;
+larger but not more difficult, for the remedy is simple, effective,
+practicable and inexpensive. Destroy their breeding-places and you will
+have no flies. As the flies breed principally in manure the first
+remedial measure is to see that all manure is removed from the
+barn-yard<span class='pagenum'><a name="Page_72" id="Page_72">[Pg 72]</a></span> at least once a week and spread over the fields to dry, for
+the flies cannot breed in the dry manure. If it is not practicable to
+remove it this often the manure should be kept in a bin that is closed
+so tight that no flies can get into it to lay their eggs. Sometimes the
+manure may be treated with some substance such as kerosene, crude oil,
+chlorid of lime, tobacco water or mixture of two or more of these and
+thus rendered unsuitable for the flies to breed in, but in general
+practice none of them has been found very satisfactory for the treatment
+is either not thorough enough or is too expensive of time and material.</p>
+
+<p>Outdoor privies and cesspools must be carefully attended to. The latter
+can be easily covered so no flies can get in and if the filthy and in
+every way dangerous pit under the privy be filled and the dry-earth
+closet substituted one of the greatest sources of danger, especially in
+the country and in towns with inadequate sewerage facilities, will be
+done away with. After these things are done there remain only the
+garbage cans and the rubbish heaps to look after.</p>
+
+<p>Of course your neighbor must keep his place clean too, for his flies are
+just as apt to come into your house as his, so the problem becomes one
+for the whole community.</p>
+
+<p><span class='pagenum'><a name="Page_73" id="Page_73">[Pg 73]</a></span></p><p>Almost all cities and many of the smaller towns have ordinances which
+if enforced would afford adequate protection from flies, but they are
+seldom if ever rigidly enforced and it yet remains for some enterprising
+town to be able to advertise itself as a "speckless town" as well as a
+"spotless town."</p>
+
+
+<p class="center">AN EXPERT'S OPINION</p>
+
+<p>In a recent important bulletin issued by the Bureau of Entomology, Dr.
+L.O. Howard discusses the economic importance of several of the insects
+that carry disease. I wish to quote two or three paragraphs from the
+pages in which he discusses the house-fly or typhoid fly to show the
+opinion of this excellent authority in regard to this pest.</p>
+
+<div class="blockquot"><p>"Even if the typhoid or house fly were a creature difficult to
+destroy, the general failure on the part of communities to make any
+efforts whatever to reduce its numbers could properly be termed
+criminal neglect; but since, as will be shown, it is comparatively
+an easy matter to do away with the plague of flies, this neglect
+becomes an evidence of ignorance or of a carelessness in regard to
+disease-producing filth which to the informed mind constitutes a
+serious blot on civilized methods of life." </p></div>
+
+<p>On another page:</p>
+
+<p><span class='pagenum'><a name="Page_74" id="Page_74">[Pg 74]</a></span></p><div class="blockquot"><p>"We have thus shown that the typhoid or house fly is a general and
+common carrier of pathogenic bacteria. It may carry typhoid fever,
+Asiatic cholera, dysentery, cholera morbus, and other intestinal
+diseases; it may carry the bacilli of tuberculosis and certain eye
+diseases. It is the duty of every individual to guard so far as
+possible against the occurrence of flies upon his premises. It is
+the duty of every community, through its board of health, to spend
+money in the warfare against this enemy of mankind. This duty is as
+pronounced as though the community were attacked by bands of
+ravenous wolves." </p></div>
+
+<p>Again:</p>
+
+<div class="blockquot"><p>"A leading editorial in an afternoon paper of the city of
+Washington, of October 20, 1908, bears the heading, 'Typhoid a
+National Scourge,' arguing that it is to-day as great a scourge as
+tuberculosis. The editorial writer might equally well have used the
+heading 'Typhoid a National Reproach,' or perhaps even 'Typhoid a
+National Crime,' since it is an absolutely preventable disease. And
+as for the typhoid fly, that a creature born in indescribable filth
+and absolutely swarming with disease germs should practically be
+invited to multiply unchecked, even in great centers of population,
+is surely nothing less than criminal." </p></div>
+
+<p>The whole bulletin (No. 78, Bureau of Entomology) should be read and
+studied by all who are interested in this subject.</p>
+
+
+<p><span class='pagenum'><a name="Page_75" id="Page_75">[Pg 75]</a></span></p><p class="center">OTHER FLIES</p>
+
+<p>Occasionally other flies looking more or less like the house-fly are
+seen in houses. Some of these have the same type of sucking mouth-parts
+and have habits very similar to the house-fly, but as they are usually
+much less common and as nearly all that has been said in regard to the
+house-fly would apply equally well to them and as the same measures
+should be adopted in fighting them they need not be discussed further
+here.</p>
+
+<p>I have already called attention to the fact that a fly which looks very
+much like the house-fly is sometimes found in the house and will often
+bite severely. It has quite a different style of beak, one that is
+fitted for piercing so it may suck the blood of its victim (<a href="#Fig_51">Fig. 51</a>). As
+these flies often seem to be more persistent before a rain the weather
+prophet will tell you that "It is surely going to rain for the
+house-flies are beginning to bite."</p>
+
+<p>These stable-flies, as they are called, are great pests of cattle and
+horses in some sections. It is thought that they are important factors
+in the spread of some of the diseases of domestic animals, and their
+habit of sometimes attacking human beings makes it possible for them to
+carry certain disease germs from animals to man or from man to man.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_76" id="Page_76">[Pg 76]</a></span></p>
+<h2><a name="CHAPTER_VI" id="CHAPTER_VI"></a>CHAPTER VI</h2>
+
+<h3>MOSQUITOES</h3>
+
+<div class="figdrop">
+<img src="images/dropm.jpg" width="75" height="76" alt="dropm" title="" />
+</div>
+<p class="noin"><span class="caps">osquitoes</span> are no more abundant now than they have been in the past, but
+when Linn&aelig;us in 1758 made his list of all the animals known to exist at
+that time he catalogued only six species of mosquitoes. Only a few years
+ago, 1901, Dr. Theobald of the British Museum published a book on the
+mosquitoes of the world in which he listed three hundred and forty-three
+kinds. Soon other volumes appeared, adding more species, and
+systematists everywhere have been describing new ones until now the
+total number of described species is probably over five hundred, more
+than sixty of which occur in the United States.</p>
+
+<p>This shows only one phase of the great interest that has been taken in
+the mosquitoes since the discovery of their importance as carriers of
+disease. Not only have they been studied from a systematic standpoint
+but an endless amount of work has been done and is being done in
+studying their development, habits, and structure until now, if one
+could gather together all that has been written about mosquitoes in the
+last ten or twelve years he would have a considerable library.</p>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 50, 51 and 52">
+<tr>
+ <td class="tdf"><a name="Fig_50" id="Fig_50"></a><img src="images/fig50.jpg" width="250" height="181" alt="Fig. 50" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 50</span></span></td>
+ <td class="tdf"><a name="Fig_51" id="Fig_51"></a><img src="images/fig51.jpg" width="250" height="426" alt="Fig. 51" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 51</span></span></td>
+</tr>
+<tr>
+ <td class="tdf" colspan='2'><a name="Fig_52" id="Fig_52"></a><img src="images/fig52.jpg" width="400" height="220" alt="Fig. 52" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 52</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 50</span>&mdash;Pupa of house-fly with the end broken to allow
+the fly to issue.</p>
+<p class="caption2"><span class="smcap">Fig. 51</span>&mdash;Head of stable-fly showing sharp piercing beak.</p>
+<p class="caption2"><span class="smcap">Fig. 52</span>&mdash;Mass of mosquito eggs (<i>Theobaldia incidens</i>).</p></td>
+</tr>
+</table>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_53" id="Fig_53"></a>
+<img src="images/fig53.jpg" width="400" height="311" alt="Fig. 53" title="" />
+<span class="caption"><span class="smcap">Fig. 53</span>&mdash;Mosquito eggs and larv&aelig; (<i>Theobaldia
+incidens</i>); two larv&aelig; feeding on bottom, others at surface to breathe.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_54" id="Fig_54"></a>
+<img src="images/fig54.jpg" width="400" height="188" alt="Fig. 54" title="" />
+<span class="caption"><span class="smcap">Fig. 54</span>&mdash;Mosquito larv&aelig; (<i>T. incidens</i>), dorsal view.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_77" id="Page_77">[Pg 77]</a></span></p><p>Those who are particularly interested in the group will find some of
+these books and papers easily accessible, so there may be given here
+only a brief summary of the more important facts in regard to the
+structure and habits of the mosquitoes in order that we may more readily
+understand the part that they play in the transmission of diseases and
+see the reasonableness of the recommendations in regard to fighting
+them.</p>
+
+
+<p class="center">THE EGGS</p>
+
+<p>Mosquito eggs are laid in water or in places where water is apt to
+accumulate, otherwise they will not hatch. Some species lay their eggs
+in little masses (<a href="#Fig_52">Fig. 52</a>) that float on the surface of the water,
+looking like small particles of soot. Others lay their eggs singly, some
+floating about on the surface, others sinking to the bottom where they
+remain until the young issue. Some of the eggs may remain over winter,
+but usually those laid in the summer hatch in thirty-six to forty-eight
+hours or longer according to the temperature.</p>
+
+
+<p><span class='pagenum'><a name="Page_78" id="Page_78">[Pg 78]</a></span></p><p class="center">THE LARV&AElig;</p>
+
+<p>When the larv&aelig; are ready to issue they burst open the lower end of the
+eggs and the young wrigglers escape into the water. The larv&aelig; are fitted
+for aquatic life only, so mosquitoes cannot breed in moist or damp
+places unless there is at least a small amount of standing water there.
+A very little will do, but there must be enough to cover the larv&aelig; or
+they perish.</p>
+
+<p>The head of the larv&aelig; of most species is wide and flattened. The eyes
+are situated at the sides, and just in front of them is a pair of short
+antenn&aelig; which vary with the different species.</p>
+
+<p>The mouth-parts too vary greatly according to the feeding habits. Some
+mosquito larv&aelig; are predaceous, feeding on the young of other species or
+on other insects. These of course have their mouth-parts fitted for
+seizing and holding their prey. Most of the wrigglers, however, feed on
+alg&aelig;, diatoms, Protozoa and other minute plant or animal forms which are
+swept into the mouth by curious little brush-like organs whose movements
+keep a stream of water flowing toward the mouth.</p>
+
+<p>Another group containing the <i>Anopheles</i> are intermediate between these
+two and have mouth-parts fitted for feeding on minute organisms as well
+as for attacking and holding other larger things.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_55" id="Fig_55"></a>
+<img src="images/fig55.jpg" width="400" height="303" alt="Fig. 55" title="" />
+<span class="caption"><span class="smcap">Fig. 55</span>&mdash;Eggs, larv&aelig; and pup&aelig; of mosquitoes (<i>T. incidens</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_56" id="Fig_56"></a>
+<img src="images/fig56.jpg" width="400" height="275" alt="Fig. 56" title="" />
+<span class="caption"><span class="smcap">Fig. 56</span>&mdash;Larva of mosquito (<i>T. incidens</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_57" id="Fig_57"></a>
+<img src="images/fig57.jpg" width="400" height="400" alt="Fig. 57" title="" />
+<span class="caption"><span class="smcap">Fig. 57</span>&mdash;Mosquito larv&aelig; and pup&aelig; (<i>T. incidens</i>) with
+their breathing-tubes at the surface of the water.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_58" id="Fig_58"></a>
+<img src="images/fig58.jpg" width="400" height="138" alt="Fig. 58" title="" />
+<span class="caption"><span class="smcap">Fig. 58</span>&mdash;Anopheles larv&aelig; (<i>A. maculipennis</i>) resting at
+the surface of the water.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_79" id="Page_79">[Pg 79]</a></span></p><p>A few kinds feed habitually some distance below the surface, others on
+the bottom, while still others feed always at the surface. With one or
+two exceptions, the larv&aelig; must all come to the surface to breathe (<a href="#Fig_53">Figs.
+53</a>&ndash;<a href="#Fig_57">57</a>). Most species have on the eighth abdominal segment a rather long
+breathing-tube the tip of which is thrust just above the surface of the
+water when they come up for air. In this tube are two large vessels or
+trache&aelig; which open just below the tip of the tube and extend forward
+through the whole length of the body, giving off branches here and there
+that divide into still smaller branches until every part of the body is
+reached by some of the small divisions of this tracheal system that
+carries the oxygen to all the tissues. The length of the breathing-tube
+is correlated with the feeding-habits of the larv&aelig;. <i>Anopheles</i> larv&aelig;
+which feed at the surface have very short tubes (<a href="#Fig_58">Fig. 58</a>), others that
+feed just below the surface have breathing-tubes as long or very much
+longer than the ninth abdominal segment. The last segment has at its tip
+four thin flat plates, the tracheal gills. These too are larger or
+smaller according to the habits of the larv&aelig;. Those species that feed
+close to the surface and have the tip of<span class='pagenum'><a name="Page_80" id="Page_80">[Pg 80]</a></span> the breathing-tube above the
+surface most of the time have very small tracheal gills, while those
+that feed mostly on the bottom have them well developed.</p>
+
+<p>When first hatched the larv&aelig; are of course very small. If the weather is
+warm and the food is abundant they grow very rapidly. In a few days the
+outer skin becomes rather firm and inelastic so it will not allow
+further growth. Then a new skin forms underneath and the old skin is
+cast off. This process of casting off the old skin is called molting,
+and is repeated four times during the one, two, three or more weeks of
+larval life.</p>
+
+
+<p class="center">PUPA</p>
+
+<p>With the fourth molt the active feeding larva changes to the still
+active but non-feeding pupa (<a href="#Fig_59">Fig. 59</a>). The head and thorax are closely
+united and a close inspection will reveal the head, antenn&aelig;, wings and
+legs of the adult mosquito folded away beneath the pupal skin. Instead
+of the breathing-tube on the eighth segment of the abdomen as in the
+larva, the pupa has two trumpet-shaped tubes on the back of the thorax
+through which it now gets its air from above the surface. The pupal
+stage lasts from two to five or six days or more. When the adult is
+ready to issue the pupal skin splits along the back and the mosquito
+gradually and slowly issues. It usually takes several minutes for the
+adult to issue and for its wings to become hard enough so it can fly. In
+the meantime, it is resting on the old pupal skin or on the surface of
+the water, where it is entirely at the mercy of any of its enemies that
+might happen along and is in constant danger of being tumbled over
+should the water not be perfectly smooth.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_59" id="Fig_59"></a>
+<img src="images/fig59.jpg" width="400" height="169" alt="Fig. 59" title="" />
+<span class="caption"><span class="smcap">Fig. 59</span>&mdash;Mosquito pup&aelig; (<i>T. incidens</i>) resting at the
+surface of the water.</span>
+</div>
+
+<div class="figcenter" style="width: 250px;"><a name="Fig_60" id="Fig_60"></a>
+<img src="images/fig60.jpg" width="250" height="300" alt="Fig. 60" title="" />
+<span class="caption"><span class="smcap">Fig. 60</span>&mdash;Mosquito pupa (<i>T. incidens</i>) with its
+breathing-tubes in an air bubble below the surface of the water.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_61" id="Fig_61"></a>
+<img src="images/fig61.jpg" width="400" height="260" alt="Fig. 61" title="" />
+<span class="caption"><span class="smcap">Fig. 61</span>&mdash;Mosquito larv&aelig; and pup&aelig; (<i>T. incidens</i>) resting
+at the surface of the water.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_62" id="Fig_62"></a>
+<img src="images/fig62.jpg" width="400" height="348" alt="Fig. 62" title="" />
+<span class="caption"><span class="smcap">Fig. 62</span>&mdash;A female mosquito (<i>T. incidens</i>); note the
+thread-like antenn&aelig;.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_63" id="Fig_63"></a>
+<img src="images/fig63.jpg" width="400" height="334" alt="Fig. 63" title="" />
+<span class="caption"><span class="smcap">Fig. 63</span>&mdash;A male mosquito (<i>T. incidens</i>); note the
+feathery antenn&aelig;.</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_81" id="Page_81">[Pg 81]</a></span></p><p class="center">THE ADULT</p>
+
+<p>The adult mosquito is altogether too familiar an object to need
+description, but it is necessary that we keep in mind certain particular
+points in regard to its structure, in order that we may better
+understand how it is that it is capable of transmitting disease.</p>
+
+<p>If we examine closely the antenn&aelig; of a number of mosquitoes that are
+bothering us with their too constant attentions we shall see that they
+all look very much alike (<a href="#Fig_62">Fig. 62</a>), small cylindrical joints bearing
+whorls of short fine hairs. But if we examine a number of mosquitoes
+that have been bred from a jar or aquarium we will find two types of
+antenn&aelig;, the one described above belonging to the female. The antenn&aelig; of
+the male (<a href="#Fig_63">Fig. 63</a>) are much more conspicuous on account<span class='pagenum'><a name="Page_82" id="Page_82">[Pg 82]</a></span> of the whorl of
+dense, fine, long hairs on each segment. Another interesting difference
+in the antenn&aelig; is to be noted in the size of the first joint. In both
+sexes it is short and cup-shaped, but in the male it is somewhat larger.
+This basal segment contains a highly complex auditory organ which
+responds to the vibrations of the whorls of hairs on the other segments.
+Interesting experiments have shown that these hairs vibrate best to the
+pitch corresponding to middle C on the piano, the same pitch in which
+the female "sings." Of course mosquitoes and other insects have no voice
+as we ordinarily understand the word, but produce sound by the rapid
+vibration of the wings or by the passage of air through the openings of
+the trache&aelig;. The males and females are thus easily distinguished and, as
+we shall see later, this is of some importance for only the females can
+bite. The males and females differ in another way. Just below the
+antenn&aelig; and at the sides of the proboscis or beak is a pair of three-to
+five-jointed appendages, the maxillary palpi or mouth-feelers which in
+the females of most species are very short (<a href="#Fig_64">Fig. 64</a>) while in the males
+they are usually as long as the proboscis (<a href="#Fig_65">Fig. 65</a>). The females of
+<i>Anopheles</i> and related forms have palpi quite as long as the males, but
+they are slender throughout while the male palpi are usually somewhat
+enlarged toward the tip and bear more or less conspicuous patches of
+rather long hairs or scales.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_64" id="Fig_64"></a>
+<img src="images/fig64.jpg" width="400" height="334" alt="Fig. 64" title="" />
+<span class="caption"><span class="smcap">Fig. 64</span>&mdash;Head and thorax of female mosquito
+(<i>Ochlerotatus lativittatus</i>); the short maxillary palpi are just above
+the proboscis and below the thread-like antenn&aelig;.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_65" id="Fig_65"></a>
+<img src="images/fig65.jpg" width="400" height="243" alt="Fig. 65" title="" />
+<span class="caption"><span class="smcap">Fig. 65</span>&mdash;Head and thorax of male mosquito (<i>O.
+lativittatus</i>); the maxillary palpi are as long as the proboscis.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_66" id="Fig_66"></a>
+<img src="images/fig66.jpg" width="400" height="254" alt="Fig. 66" title="" />
+<span class="caption"><span class="smcap">Fig. 66</span>&mdash;Head of female mosquito (<i>Anopheles</i>), with
+mouth-parts separated to show the needle-like parts: <i>a, a</i> antenn&aelig;;
+<i>b, b,</i> palpi; <i>c</i>, labrum; <i>d, d,</i> mandibles; <i>e</i>, hypopharynx;
+<i>f, f,</i> maxill&aelig;; <i>g</i>, labium; <i>h</i>, labella. (After Manson.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_67" id="Fig_67"></a>
+<img src="images/fig67.jpg" width="400" height="229" alt="Fig. 67" title="" />
+<span class="caption">Fig. 67&mdash;Cross-section of proboscis of female (<i>a</i>) and
+male (<i>b</i>) mosquito. <i>lxe</i>, labrum-epipharynx; <i>mn</i>, mandibles; <i>mx</i>,
+maxill&aelig;; <i>hp</i>, hypopharynx; <i>sal</i>, salivary duct; <i>li</i>, labium; <i>tr</i>,
+trachea; <i>mus</i>, muscles. (After Nuttall and Shipley.)</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_83" id="Page_83">[Pg 83]</a></span></p><p class="center">THE MOUTH-PARTS</p>
+
+<p>The mouth-parts of the mosquito are of course of particular interest to
+us. At first they appear to consist of a long slender beak or proboscis,
+but by dissecting and examining with a microscope we find this beak to
+be made up of several parts (<a href="#Fig_66">Fig. 66</a>). The labium, which is the largest
+and most conspicuous, is apparently cylindrical but is grooved above
+throughout its length. At the tip of the labium are the labell&aelig;, two
+little lobes which serve to guide the piercing organs. Lying in this
+groove along the upper side of the labium are six very fine,
+sharp-pointed needles. The uppermost of these, the labrum-epipharynx, or
+labrum as we will call it, is the largest and is really a hollow tube
+very slightly open on its under side. Just below this is the
+hypopharynx, the lateral margins of which are very thin. Down through
+the median line of the hypopharynx runs a minute duct (<a href="#Fig_67">Fig. 67</a>, sal)
+which, though exceedingly small, is of very great importance, for
+through it is poured the saliva which may carry the malaria germs into
+the wound made when the mosquito bites. The other<span class='pagenum'><a name="Page_84" id="Page_84">[Pg 84]</a></span> four needles consist
+of a pair of mandibles which are lance-shaped at the tip and a heavier
+pair of maxill&aelig;, the tips of which are serrate on one edge.</p>
+
+
+<p class="center">HOW THE MOSQUITO BITES</p>
+
+<p>When the female mosquito is feeding on man or any other animal the tip
+of the labium is placed against the surface and the six needles are
+thrust into the skin, the labell&aelig; serving as guides. As they are thrust
+deeper and deeper the labium is bowed back to allow them to enter. As
+soon as the wound is made the insect pours out through the tube of the
+hypopharynx some of the secretion from the salivary glands and then
+begins to suck up the blood through the hollow labrum into the pharynx
+and on into the stomach.</p>
+
+<p>The mouth-parts of the male differ in some important respects from those
+of the female. The hypopharynx is united to the labium, the mandibles
+are wanting and the maxill&aelig; are very much reduced so that the insect is
+unable to pierce the tough skin of animals. The male feeds on the juices
+of plants as do the females when they cannot get blood. It is not at all
+necessary for mosquitoes to have the warm blood of man or other animals.
+Comparatively few of them ever taste<span class='pagenum'><a name="Page_85" id="Page_85">[Pg 85]</a></span> blood. They have been seen feeding
+on blossoms, ripe fruit, watermelons, plant juices, etc. They are very
+fond of ripe bananas and are fed on them in the laboratory when we wish
+to keep mosquitoes for experimental purposes.</p>
+
+
+<p class="center">THE THORAX</p>
+
+<p>The middle part of the body, called the thorax, is really a strong box
+with heavy walls for the attachment of the powerful wing and leg
+muscles. The three pairs of legs are covered with hairs and scales, and
+their tips are provided with a pair of claws which vary somewhat in the
+different species. The wings (<a href="#Fig_68">Fig. 68</a>) are long and narrow with a
+characteristic venation. Along the veins and the margin of the wings are
+the scales which readily enable one to distinguish mosquitoes from other
+insects that may look much like them. In some species these scales are
+long and narrow, almost hair-like, in others they are quite broad and
+flat (<a href="#Fig_69">Fig. 69</a>). Just back of the wings is a pair of balancers, short
+thread-like processes knobbed at the end. These probably represent the
+second pair of wings with which most insects are provided, and seem to
+serve as balancers or orienting organs when the insect is flying. On the
+sides of the thorax are two small slit-like openings, the<span class='pagenum'><a name="Page_86" id="Page_86">[Pg 86]</a></span>
+breathing-pores. These are the openings into the tracheal or respiratory
+system.</p>
+
+
+<p class="center">THE ABDOMEN</p>
+
+<p>The long cylindrical abdomen is composed of eight segments. These are
+rather strongly chitinized above and below, but a narrow strip along the
+side is unchitinized. In this strip are situated the abdominal
+breathing-pores. The tip of the abdomen is furnished with a pair of
+movable organs, which in the male are variously modified and serve as
+clasping organs at mating time.</p>
+
+
+<p class="center">THE DIGESTIVE SYSTEM</p>
+
+<p>The mouth-parts of the mosquito have just been described. It will be
+remembered that the labrum is provided with a groove. Through this the
+blood or other food is sucked up by means of a strong-walled pumping
+organ, the pharynx, situated in the head (<a href="#Fig_70">Fig. 70</a>). Just back of the
+pharynx is the esophagus which leads to the beginning of the stomach.
+Close to its posterior end the esophagus gives off three food
+reservoirs, two above and a single larger one below. In dissections
+these will often be seen to be filled with minute bubbles. The stomach
+reaches from the middle of the thorax to beyond the middle of the
+abdomen. At its posterior end are given off five long slender processes,
+the Malpighian tubules which are organs of excretion, acting like the
+kidneys of higher animals. The hindgut is that portion of the intestine
+from the stomach to the end of the body.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_68" id="Fig_68"></a>
+<img src="images/fig68.jpg" width="400" height="218" alt="Fig. 68" title="" />
+<span class="caption"><span class="smcap">Fig. 68</span>&mdash;Wing of Mosquito (<i>O. lativittatus</i>).</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_69" id="Fig_69"></a>
+<img src="images/fig69.jpg" width="400" height="376" alt="Fig. 69" title="" />
+<span class="caption"><span class="smcap">Fig. 69</span>&mdash;End of mosquito wing highly magnified to show the scales on the veins.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_70" id="Fig_70"></a>
+<img src="images/fig70.jpg" width="400" height="147" alt="Fig. 70" title="" />
+<span class="caption"><span class="smcap">Fig. 70</span>&mdash;Diagram to show the alimentary canal and salivary glands of a mosquito.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_71" id="Fig_71"></a>
+<img src="images/fig71.jpg" width="400" height="275" alt="Fig. 71" title="" />
+<span class="caption"><span class="smcap">Fig. 71</span>&mdash;Salivary glands of <i>Culex</i> at right. <i>Anopheles</i> at left. (After Christophers.)</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_87" id="Page_87">[Pg 87]</a></span></p><p class="center">THE SALIVARY GLANDS</p>
+
+<p>Lying under the alimentary canal in the forward part of the thorax are
+the salivary glands. There are two sets of these, each having three
+lobes with a common duct which joins the duct from the other set a short
+distance before they enter the base of the hypopharynx. Each of these
+lobes is made up of a layer of secreting cells (<a href="#Fig_71">Fig. 71</a>) which produces
+the saliva that is poured into the wound as soon as the insect pierces
+the skin of the victim, and we shall see, too, that the malarial germs
+also collect in these glands to be carried by the saliva to the new
+host.</p>
+
+
+<p class="center">EFFECTS OF THE BITE</p>
+
+<p>After a mosquito has bitten a person and withdrawn the stylets, a small
+area about the puncture whitens, then soon becomes pink and begins to
+swell, then to itch and burn. Some people suffer much more from the
+bites of mosquitoes than do others. For some such bites mean little or
+no inconvenience,<span class='pagenum'><a name="Page_88" id="Page_88">[Pg 88]</a></span> indeed may pass wholly unnoticed, to others a single
+bite may mean much annoyance, and several bites may cause much
+suffering.</p>
+
+<p>After an hour or so the itching usually ceases, but in some cases it
+continues longer. In some instances little or no irritation is felt
+until some hours, sometimes as much as a day, after the bite. In such
+cases the effect of the bite is apt to be severe and to last for several
+days. Sometimes a more or less serious sore will follow a bite, probably
+due to infection of the wound by scratching. It is doubtless the saliva
+that is poured into the wound that causes the irritation. It is
+frequently asserted that if the mosquito is allowed to drink its fill
+and withdraw its beak without being disturbed no evil results will
+follow. Those who hold this theory say that the saliva that is poured
+into the wound is all withdrawn again with the blood if the mosquito is
+allowed to feed long enough. There may be some truth in this, but for
+most of us a bite means a hurt anyway and few will be content to sit
+perfectly still and watch the little pest gradually fill up on blood.</p>
+
+<p>It is not known just what the action of the saliva is, its composition
+or reaction on the tissues. It is generally supposed to prevent
+coagulation of the blood that is to be drawn through the narrow tube<span class='pagenum'><a name="Page_89" id="Page_89">[Pg 89]</a></span> of
+the labrum. Others think that its presence causes a greater flow of
+blood to the wound. But the sad part of it is, for us at least, that it
+hurts and may cause malaria and possibly other diseases.</p>
+
+
+<p class="center">HOW MOSQUITOES BREATHE</p>
+
+<p>Mosquitoes and other insects do not have any nostrils nor do they
+breathe through any openings on the head. Along the sides of the thorax
+and abdomen is a series of very minute openings known as the spiracles.
+Through these the air passes into a system of air-tubes, the trache&aelig;.
+There are two main trunks or divisions of the trache&aelig; just inside the
+body-wall and a number of shorter connecting trunks. From these larger
+vessels arise a great number of smaller ones which branch and subdivide
+again and again until all the tissues are supplied by these minute
+little air-tubes that carry the oxygen to all parts of the body and
+carry off the waste carbon dioxid. These air-tubes are emptied and
+filled by the contractions of the walls of the abdomen. When the
+body-wall contracts the air is forced out of the thin-walled trachea
+through the spiracles; when the pressure is removed they are refilled by
+the fresh air rushing in.</p>
+
+
+<p><span class='pagenum'><a name="Page_90" id="Page_90">[Pg 90]</a></span></p><p class="center">THE BLOOD</p>
+
+<p>After a mosquito has been feeding on a man or some other animal it is
+often so distended that the blood shows rich and red through the thin
+sides of the walls of the abdomen. This, however, is the blood of the
+victim and not of the mosquito. The blood of insects is not red but pale
+yellowish or greenish. It is not confined in definite vessels, but fills
+all the space inside the body cavity that is not occupied by some of the
+tissues or organs. It bathes the walls of the alimentary canal and
+gathers there the nourishment which it carries to all parts of the body.
+It does not carry oxygen or collect the carbon dioxid as does the blood
+of higher animals. That work, as we have just seen, is done by the
+air-tubes. Above the alimentary canal, extending almost the whole length
+of the abdomen and thorax, is a thin-walled pulsating vessel, the heart.
+This consists of a series of chambers each communicating with the one in
+front of it by an opening which is guarded by a valve. When one of these
+chambers contracts it forces the blood that is in it forward into the
+next chamber which, in its turn, sends it on. As the walls relax the
+valves at the sides are opened and the blood that is in the body-cavity
+rushes in to fill the empty chamber. As these regular rythmical
+pulsations recur the blood is forced forward through the heart into the
+head where it bathes the organs there. We shall see in another chapter
+that the malarial parasite escapes from the walls of the stomach of the
+mosquito into the blood in the body-cavity and finally reaches the
+salivary glands. As the heart is constantly driving blood to this part
+of the body the parasites readily reach the glands from which they
+finally escape into the new host.</p>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 72 and 73">
+<tr>
+ <td class="tdf"><a name="Fig_72" id="Fig_72"></a><img src="images/fig72.jpg" width="250" height="234" alt="Fig. 72" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 72</span></span></td>
+ <td class="tdf"><a name="Fig_73" id="Fig_73"></a><img src="images/fig73.jpg" width="250" height="243" alt="Fig. 73" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 73</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 72</span>&mdash;Heads of Culicin&aelig; mosquitoes; <i>a</i>, male; <i>b</i>,
+female. (After Manson.)</p>
+<p class="caption2"><span class="smcap">Fig. 73</span>&mdash;Heads of Anophelin&aelig; mosquitoes; <i>c</i>, male; <i>d</i>,
+female. (After Manson.)</p></td>
+</tr>
+</table>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_74" id="Fig_74"></a>
+<img src="images/fig74.jpg" width="400" height="164" alt="Fig. 74" title="" />
+<span class="caption"><span class="smcap">Fig. 74</span>&mdash;Wing of <i>Anopheles maculipennis</i>.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_75" id="Fig_75"></a>
+<img src="images/fig75.jpg" width="400" height="164" alt="Fig. 75" title="" />
+<span class="caption"><span class="smcap">Fig. 75</span>&mdash;Wing of <i>Theobaldia incidens</i>.</span>
+</div>
+
+<table border="0" cellpadding="0" cellspacing="0" style="width: 600px; margin-top: 1em; margin-bottom: 1em;" summary="Figs. 76, 77, 78 and 79">
+<tr>
+ <td class="tdf"><a name="Fig_76" id="Fig_76"></a><img src="images/fig76.jpg" width="200" height="426" alt="Fig. 76" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 76</span></span></td>
+ <td class="tdf"><a name="Fig_77" id="Fig_77"></a><img src="images/fig77.jpg" width="200" height="438" alt="Fig. 77" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 77</span></span></td>
+</tr>
+<tr>
+ <td class="tdf"><a name="Fig_78" id="Fig_78"></a><img src="images/fig78.jpg" width="250" height="321" alt="Fig. 78" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 78</span></span></td>
+ <td class="tdf"><a name="Fig_79" id="Fig_79"></a><img src="images/fig79.jpg" width="250" height="338" alt="Fig. 79" title="" /><br />
+   <span class="caption"><span class="smcap">Fig. 79</span></span></td>
+</tr>
+<tr>
+ <td align='left' colspan='2'>
+<p class="caption2"><span class="smcap">Fig. 76</span>&mdash;A non-malarial mosquito (<i>T. incidens</i>), male,
+standing on the wall.</p>
+<p class="caption2"><span class="smcap">Fig. 77</span>&mdash;Female of same.</p>
+<p class="caption2"><span class="smcap">Fig. 78</span>&mdash;A malarial mosquito (<i>A. maculipennis</i>), male,
+standing on the wall.</p>
+<p class="caption2"><span class="smcap">Fig. 79</span>&mdash;Female of same.</p></td>
+</tr>
+</table>
+
+
+<p><span class='pagenum'><a name="Page_91" id="Page_91">[Pg 91]</a></span></p><p class="center">CLASSIFICATION</p>
+
+<p>For our purpose it will not be necessary to try to give a system of
+classification of all the mosquitoes. Those interested in this phase of
+the subject will find several books and papers devoted wholly to it. It
+is quite important, however, that we know something about a few of the
+more familiar groups and kinds, especially those concerned in the
+transmission of diseases.</p>
+
+
+<p class="center">THE ANOPHELES</p>
+
+<p>In pointing out the differences between male and female mosquitoes we
+noted that in one group, the genus <i>Anopheles</i>, both sexes have long
+maxillary palpi (<a href="#Fig_72">Figs. 72</a>, <a href="#Fig_73">73</a>). This is the most important character
+separating this genus from the other<span class='pagenum'><a name="Page_92" id="Page_92">[Pg 92]</a></span> common forms and as the
+<i>Anopheles</i> are the malaria carriers it is important that this
+difference be remembered. Most of the members of this group have spotted
+wings (<a href="#Fig_74">Fig. 74</a>), but as some other common kinds also have spotted wings
+(<a href="#Fig_75">Fig. 75</a>) this character will not always be reliable. When an
+<i>Anopheles</i> mosquito is at rest the head and proboscis are held in one
+line with the body and the body rests at a considerable angle to the
+surface on which it is standing. Other kinds rest with the body almost
+or quite parallel to the surface on which they are standing. So if you
+find a female mosquito with long mouth-palpi and spotted wings resting
+at an angle to the surface on which it stands you may be reasonably sure
+that it is an <i>Anopheles</i> and therefore may be dangerous (<a href="#Fig_76">Figs. 76</a>, <a href="#Fig_77">77</a>,
+<a href="#Fig_78">78</a>, <a href="#Fig_79">79</a>).</p>
+
+<p>In the United States there are three species of
+<i>Anopheles</i>&mdash;<i>maculipennis</i>, <i>punctipennis</i> and <i>crucians</i>&mdash;which are
+common in various localities, and one or two other species that so far
+as known are local or rare.</p>
+
+<p>The <i>Anopheles</i> eggs are not laid in masses as are the eggs of many
+other mosquitoes, but are deposited singly on the surface of the water
+where they may be found often floating close together.</p>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_80" id="Fig_80"></a>
+<img src="images/fig80.jpg" width="350" height="109" alt="Fig. 80" title="" />
+<span class="caption"><span class="smcap">Fig. 80</span>&mdash;Egg of Anopheles, side view. (After Nuttall and Shipley.)</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_81" id="Fig_81"></a>
+<img src="images/fig81.jpg" width="350" height="148" alt="Fig. 81" title="" />
+<span class="caption"><span class="smcap">Fig. 81</span>&mdash;Egg of Anopheles, dorsal view. (After Nuttall and Shipley.)</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_82" id="Fig_82"></a>
+<img src="images/fig82.jpg" width="400" height="152" alt="Fig. 82" title="" />
+<span class="caption"><span class="smcap">Fig. 82</span>&mdash;Anopheles larv&aelig;, the one to the right feeding.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_83" id="Fig_83"></a>
+<img src="images/fig83.jpg" width="350" height="94" alt="Fig. 83" title="" />
+<span class="caption"><span class="smcap">Fig. 83</span>&mdash;Anopheles larv&aelig;, the one to the right feeding,
+the other just coming to the surface.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_84" id="Fig_84"></a>
+<img src="images/fig84.jpg" width="400" height="160" alt="Fig. 84" title="" />
+<span class="caption"><span class="smcap">Fig. 84</span>&mdash;Anopheles larva, dorsal view.</span>
+</div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_85" id="Fig_85"></a>
+<img src="images/fig85.jpg" width="350" height="167" alt="Fig. 85" title="" />
+<span class="caption"><span class="smcap">Fig. 85</span>&mdash;Anopheles pup&aelig; resting at surface of water.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_93" id="Page_93">[Pg 93]</a></span></p><p>The eggs (<a href="#Fig_80">Figs. 80</a>, <a href="#Fig_81">81</a>) are elliptical in outline and are provided with
+a characteristic membranous expansion near the middle.</p>
+
+<p>The larv&aelig; may be found at the proper season and in the localities where
+they are abundant in almost any kind of standing water, in clear little
+pools beside running streams, in the overflow from springs, in swamps
+and marshy lands, in rain-barrels or any other places or vessels where
+the water is quiet. They do not breed in brackish water. As they feed
+largely on the alg&aelig; or green scum on the surface of the water they are
+especially apt to be found where this is present. We have already noted
+that their positions in the water differ from that assumed by other
+species (<a href="#Fig_82">Fig. 82</a>).</p>
+
+<p>As the breathing-tube is very short the larv&aelig; must come close to the
+surface to breathe, and when they are feeding we find them lying just
+under and parallel to the surface of the water with their curious round
+heads turned entirely upside down as they feed on the particles that are
+floating on the surface (<a href="#Fig_83">Figs. 83</a>, <a href="#Fig_84">84</a>).</p>
+
+<p>The pup&aelig; do not differ very much from the pup&aelig; of other species although
+the breathing-tubes on the thorax are usually shorter and the creature
+usually rests with its abdomen closer to the surface, that is, it does
+not hang down from the surface quite as straight as do other forms (<a href="#Fig_85">Fig.
+85</a>).</p>
+
+<p><span class='pagenum'><a name="Page_94" id="Page_94">[Pg 94]</a></span></p><p>The adults may be found out of doors or in houses, barns or other
+outbuildings. They do not seem to like a draft and consequently will be
+more apt to frequent rooms or places where there is little circulation
+of air. Although they are usually supposed to fly and bite only in the
+evening or at night, they may occasionally bite in the daytime. One
+hungry female took two short meals from my arm while we were trying to
+get her to pose for a photograph one warm afternoon.</p>
+
+<p>The female passes the winter in the adult condition, hibernating in any
+convenient place about old trees or logs, in cracks or crevices in doors
+or out of doors. In the house they hide in the closets, behind the
+bureau, behind the head of the bed, or underneath it, or in any place
+where they are not apt to be disturbed. During a warm spell in the
+winter or if the room is kept warm they may come out for a meal almost
+any time.</p>
+
+
+<p class="center">THE YELLOW FEVER MOSQUITO</p>
+
+<p>Ranking next in importance to <i>Anopheles</i> as a disseminator of disease
+and in fact solely responsible for a more dreaded scourge, is the
+species of mosquito now known as <i>Stegomyia calopus</i>. While this species
+is usually restricted to tropical or semi-tropical regions it sometimes
+makes its appearance<span class='pagenum'><a name="Page_95" id="Page_95">[Pg 95]</a></span> in places farther north, especially in summer
+time, where it may thrive for a time. The adult mosquito (<a href="#Fig_104">Fig. 104</a>) is
+black, conspicuously marked with white. The legs and abdomen are banded
+with white and on the thorax is a series of white lines which in
+well-preserved specimens distinctly resembles a lyre. These mosquitoes
+are essentially domestic insects, for they are very rarely found except
+in houses or in their immediate vicinity. Once they enter a room they
+will scarcely leave it except to lay their eggs in a near-by cistern,
+water-pot, or some other convenient place.</p>
+
+<p>Their habit of biting in the daytime has gained for them the name of
+"day mosquitoes" to distinguish them from the night feeders. But they
+will bite at night as well as by day and many other species are not at
+all adverse to a daylight meal, if the opportunity offers, so this habit
+is not distinctive. The recognition of these facts has a distinct
+bearing in the methods adopted to prevent the spread of yellow fever.
+There are no striking characters or habits in the larval or pupal stages
+that would enable us to distinguish without careful examination this
+species from other similar forms with which it might be associated. For
+some time it was claimed that this species would breed only in clean
+water, but it has been found that it is not<span class='pagenum'><a name="Page_96" id="Page_96">[Pg 96]</a></span> nearly so particular, some
+even claiming that it prefers foul water. I have seen them breeding in
+countless thousands in company with <i>Stegomyia scutellaris</i> and <i>Culex
+fatigans</i> in the sewer drains in Tahiti in the streets of Papeete. As
+the larv&aelig; feed largely on bacteria one would expect to find them in
+exactly such places where the bacteria are of course abundant.</p>
+
+<p>The fact that they are able to live in any kind of water and in a very
+small amount of it well adapts them to their habits of living about
+dwellings.</p>
+
+<p>So far as known the members of these two genera are the only two that
+are concerned in the transmission of disease in the United States. In
+other countries other species are suspected or proven disseminators of
+certain diseases, but these will be discussed in connection with the
+particular diseases in later chapters.</p>
+
+
+<p class="center">OTHER SPECIES</p>
+
+<p>The many other species of mosquitoes that we have may be conveniently
+divided as to their breeding-habits into the fresh-water and the
+brackish-water forms. Among the fresh-water kinds some are found
+principally associated with man and his dwelling places, others live in
+the woods or other places and so are far less troublesome.<span class='pagenum'><a name="Page_97" id="Page_97">[Pg 97]</a></span> Most of
+these do not fly far. Several of the species that breed in brackish
+water are great travelers and may fly inland for several miles. Thus the
+towns situated from one to three or four miles inland from the lower
+reaches of San Francisco Bay are often annoyed more by the mosquitoes
+that breed only in the brackish water on the salt marshes than they are
+by any of the fresh-water forms (<a href="#Fig_86">Figs. 86</a>, <a href="#Fig_87">87</a>). The worst mosquito pest
+along the coast of the eastern United States and for some distance
+inland is a species that breeds in the salt marshes.</p>
+
+
+<p class="center">NATURAL ENEMIES OF MOSQUITOES</p>
+
+<p>In combating noxious insects we learned long ago that often the most
+efficient, the easiest and cheapest way is to depend on their natural
+enemies to hold them in check. Under normal or rather natural conditions
+we find that they are usually kept within reasonable bounds by their
+natural enemies, but under the artificial conditions brought about by
+the settling and developing of any district great changes come about. It
+very often happens that these changes are favorable to the development
+of the noxious insects and unfavorable to the development of their
+enemies.</p>
+
+<p>A striking example and one to the point is afforded<span class='pagenum'><a name="Page_98" id="Page_98">[Pg 98]</a></span> in the introduction
+of mosquitoes into Hawaii. Up to 1826 there were no mosquitoes on these
+islands. It is supposed that they were introduced about that time by
+some ships that were trading at the islands. Indeed it is claimed that
+the very ship is known that brought them over from Mexico.</p>
+
+<p>Once introduced they found conditions there very favorable to their
+development, plenty of standing water and few natural enemies to prey on
+them, so they increased very rapidly and gradually spread over all the
+islands of the group. This was the so-called night mosquito, <i>Culex
+pipiens</i>. Much later another species, <i>Stegomyia calopus</i>, just as
+annoying and much more dangerous was introduced and has also become very
+troublesome. We have a few species of top-minnows (<a href="#Fig_88">Fig. 88</a>) occurring in
+sluggish streams in the southern part of the United States that are
+important enemies of the mosquitoes of that region. A few years ago some
+of these were taken over to Hawaii and liberated in suitable places to
+see if they would not help solve the mosquito problem there. The fishes
+seem to be doing well. Already they are destroying many mosquito larv&aelig;,
+and there are indications that they are going to do an important work,
+but of course can be depended on only as an aid.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_86" id="Fig_86"></a>
+<img src="images/fig86.jpg" width="400" height="457" alt="Fig. 86" title="" />
+<span class="caption"><span class="smcap">Fig. 86</span>&mdash;Salt-marsh mosquito (<i>Ochlerotatus lativittatus</i>); male.</span>
+</div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_87" id="Fig_87"></a>
+<img src="images/fig87.jpg" width="400" height="439" alt="Fig. 87" title="" />
+<span class="caption"><span class="smcap">Fig. 87</span>&mdash;Salt-marsh mosquito (<i>O. lativittatus</i>); female.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 350px;"><a name="Fig_88" id="Fig_88"></a>
+<img src="images/fig88.jpg" width="350" height="162" alt="Fig. 88" title="" />
+<span class="caption"><span class="smcap">Fig. 88</span>&mdash;Top-minnow (<i>Mollienisia latipinna</i>). (From Bull., 47 U.S. Fish Com.)</span>
+</div>
+
+<div class="figcenter" style="width: 500px;"><a name="Fig_89" id="Fig_89"></a>
+<img src="images/fig89.jpg" width="500" height="330" alt="Fig. 89" title="" />
+<span class="caption"><span class="smcap">Fig. 89</span>&mdash;Dragon-flies. (From Kellogg&#39;s Amer. Insects.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_99" id="Page_99">[Pg 99]</a></span></p><p>On account of the various habits of both the larv&aelig; and adults it will
+never be possible for any natural enemy or group of natural enemies
+effectively to control the mosquitoes of any region, but as certain of
+them are important as helpers they deserve to be mentioned.</p>
+
+
+<p class="center">ENEMIES OF THE ADULTS</p>
+
+<p>Birds devour a few mosquitoes, the night-flying forms being particularly
+serviceable, but the number thus destroyed is probably so small as to be
+of little practical importance.</p>
+
+<p>The dragon-flies (<a href="#Fig_89">Figs. 89</a>, <a href="#Fig_90">90</a>, <a href="#Fig_91">91</a>) or mosquito hawks have long been
+known as great enemies of mosquitoes, and they certainly do destroy many
+of them as they are hawking about places where mosquitoes abound. Dr.
+J.B. Smith of New Jersey very much doubts their efficiency, but
+observations made by other scientific men would seem to indicate that
+they often devour large numbers of mosquitoes during the course of the
+day and evening.</p>
+
+<p>Spiders and toads destroy a few mosquitoes each night. Certain external
+and internal parasites destroy a few more, but the sum total of all of
+these agencies is probably not very considerable, for while the adults
+may have several natural enemies<span class='pagenum'><a name="Page_100" id="Page_100">[Pg 100]</a></span> they are not of sufficient importance
+to have any appreciable effect on the number of mosquitoes in a badly
+infested region.</p>
+
+
+<p class="center">ENEMIES OF THE LARV&AElig; AND PUP&AElig;</p>
+
+<p>The larv&aelig; and pup&aelig; on the other hand have many important enemies. Indeed
+under favorable conditions these may keep small ponds or lakes quite
+free from the pests. The predaceous aquatic larv&aelig; of many insects feed
+freely on wrigglers. The larv&aelig; of the diving beetles which are known as
+water-tigers are particularly ferocious and will soon destroy all the
+wrigglers in ponds where they are present (<a href="#Fig_92">Fig. 92</a>). Dragon-fly larv&aelig;
+also feed freely on mosquito larv&aelig;. Whirligig beetles are said to be
+particularly destructive to <i>Anopheles</i> larv&aelig; and many other insects
+such as water-boatmen, back-swimmers, etc., feed on the larv&aelig; of various
+species. A few of these introduced into a breeding-jar with <i>Anopheles</i>
+larv&aelig; will soon destroy all of them, even the very young bugs attacking
+larv&aelig; much larger than themselves.</p>
+
+<p>It is interesting to note that the larv&aelig; of some mosquitoes are
+themselves predaceous and feed freely on the other wrigglers that may
+chance to be in the same locality.</p>
+
+<div class="figcenter" style="width: 300px;"><a name="Fig_90" id="Fig_90"></a>
+<img src="images/fig90.jpg" width="300" height="313" alt="Fig. 90" title="" />
+<span class="caption"><span class="smcap">Fig. 90</span>&mdash;The young (nymph) of a dragon-fly. (From Kellogg&#39;s Amer. Insects.)</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_91" id="Fig_91"></a>
+<img src="images/fig91.jpg" width="400" height="275" alt="Fig. 91" title="" />
+<span class="caption"><span class="smcap">Fig. 91</span>&mdash;The cast skin (exuv&aelig;) of a dragon-fly nymph.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_92" id="Fig_92"></a>
+<img src="images/fig92.jpg" width="450" height="356" alt="Fig. 92" title="" />
+<span class="caption"><span class="smcap">Fig. 92</span>&mdash;Diving-beetles and back-swimmers. (From Kellogg&#39;s Amer. Insects.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_101" id="Page_101">[Pg 101]</a></span></p><p>Various species of fish are, however, the most important enemies of the
+mosquitoes. Great schools of tide-water minnows (<a href="#Fig_93">Fig. 93</a>) are often
+carried over the low salt-marshes by the extreme high-tides and left in
+the hundreds of tide pools as the tide recedes. No mosquitoes can breed
+in a pool thus stocked with these fish. In the fresh-water streams and
+lakes there are several species of the top-minnows, sticklebacks (<a href="#Fig_94">Fig.
+94</a>), etc., that feed voraciously on mosquito larv&aelig; and unless the grass
+or reeds prevent the fish from getting to all parts of the ponds or
+lakes very few mosquitoes can breed in places where they are present.</p>
+
+<p>Minute red mites such as attack the house-flies and other insects
+sometimes attack adult mosquitoes, but they are rarely very abundant.
+Parasitic roundworms attack certain species. Others suffer more or less
+from the attacks of various Sporozoan parasites.</p>
+
+
+<p class="center">FIGHTING MOSQUITOES</p>
+
+<p>When mosquitoes are bothering us we usually begin by trying to kill the
+individual pests that are nearest to us. We try to crush them if they
+bite us; we screen the doors and windows to keep them from the house. In
+warmer countries the people are a little more hospitable and do not
+screen the mosquitoes out of the house entirely, but screen the beds for
+protection at night, and if the mosquitoes<span class='pagenum'><a name="Page_102" id="Page_102">[Pg 102]</a></span> get too insistent during the
+day the bed makes a safe and comfortable retreat. All the mosquitoes in
+a room may be killed by fumigating with sulphur at the rate of two
+pounds to the thousand cubic feet of air-space. Pyrethrum is also used
+largely, but it only stupefies the mosquitoes temporarily instead of
+killing them. While in that condition they may be swept up and
+destroyed.</p>
+
+<p>Various substances are sometimes used as repellants by those who must be
+in regions where the mosquitoes are abundant. With many of these,
+however, "the cure is worse than the disease." Smudges are often built
+to the windward of a house or barn-yard and the smoke from a good
+smoldering fire will keep a considerable area quite free from
+mosquitoes. The man who can keep himself enveloped in a cloud of tobacco
+smoke will not be bothered by mosquitoes. Oil of pennyroyal, oil of tar
+or a mixture of these with olive oil, and various other concoctions are
+sometimes smeared over the face and hands. These will furnish protection
+as long as they last. Dr. Smith says that he has found oil of citronella
+quite effective and of course less objectionable than the other things
+usually used. Care should be taken not to get it in the eyes. An
+ointment made of cedar oil, one ounce; oil of citronella, two ounces;
+spirits of camphor, two ounces, is said to make a good repellant and is
+effective for a long time.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_93" id="Fig_93"></a>
+<img src="images/fig93.jpg" width="400" height="179" alt="Fig. 93" title="" />
+<span class="caption"><span class="smcap">Fig. 93</span>&mdash;Killifish (<i>Fundulus heteroliatus</i>). (From Bull. 47, U.S. Fish Com.)</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_94" id="Fig_94"></a>
+<img src="images/fig94.jpg" width="400" height="160" alt="Fig. 94" title="" />
+<span class="caption"><span class="smcap">Fig. 94</span>&mdash;Stickleback (<i>Apeltes quadracus</i>). (From Bull. 47, U.S. Fish Com.)</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 450px;"><a name="Fig_95" id="Fig_95"></a>
+<img src="images/fig95.jpg" width="450" height="281" alt="Fig. 95" title="" />
+<span class="caption"><span class="smcap">Fig. 95</span>&mdash;An old watering trough, an excellent breeding-place for mosquitoes.</span>
+</div>
+
+
+<p><span class='pagenum'><a name="Page_103" id="Page_103">[Pg 103]</a></span></p><p class="center">FIGHTING THE LARV&AElig;</p>
+
+<p>All of the efforts directed against the adult mosquitoes are usually of
+little avail in decreasing the number in any region. It is comparatively
+easy, however, to fight them successfully in the larval stage. We have
+seen that standing water is absolutely necessary for mosquitoes to breed
+in. This makes the problem much simpler than if they could breed in any
+moist places such as well-sprinkled lawns, a shady part of the garden,
+etc. The whole problem of successful campaigns against the mosquitoes
+resolves itself into the problem of finding and destroying or properly
+treating their breeding-places. We have seen how certain kinds, such as
+the yellow fever mosquito, are "domestic" species. They never go far
+from their breeding-places. If a house is infected by one of these
+species the immediate premises should be searched for the source.
+Cisterns, rain-barrels, sewer-traps, cesspools, tubs or buckets of water
+or old tin cans in out-of-the-way corners, are all suitable places for
+them to breed in. Cisterns and rain-barrels should be thoroughly
+screened so that no mosquitoes can get in or out, or the surface should<span class='pagenum'><a name="Page_104" id="Page_104">[Pg 104]</a></span>
+be covered with a film of kerosene which will kill all the larv&aelig; in the
+water when they come to the surface to breathe, and will also kill the
+females when they come to deposit their eggs. The vent to open cesspools
+should be thoroughly screened or the surface of the water kept well
+covered with oil. Water standing in any vessels in the yards should be
+emptied every week or ten days and the old tin cans destroyed or hauled
+away. In fighting these domestic species you need be concerned only with
+your own yard and that of your near-by neighbors. Other species, while
+also rather local in their distribution, fly much farther than the
+really domestic ones. In fighting these the region for a considerable
+distance around must be taken into consideration. Watering-troughs (<a href="#Fig_95">Fig.
+95</a>) that are left filled from week to week, the overflow from such
+places, and the tracks made in the mud round about them (<a href="#Fig_96">Fig. 96</a>), small
+sluggish streams, irrigating ditches, and small ponds or lakes not
+supplied with fish are excellent breeding-places for several species of
+mosquitoes including <i>Anopheles</i> and others. The remedy at once suggests
+itself. The watering-trough can be emptied and renewed every week during
+the summer time, the overflow can be taken care of in a ditch that will
+lead it away from the trough to where it will sink into the ground, the<span class='pagenum'><a name="Page_105" id="Page_105">[Pg 105]</a></span>
+banks of the streams or ponds or lakes can be cleared in such a way that
+fish can get to all parts of the water; most of the small ponds can be
+drained or their surface may be covered over with a thin film of
+kerosene. This is best applied as a spray; one ounce to fifteen square
+feet will suffice. If the oil is simply poured over the surface more
+will be required.</p>
+
+<p>The fighting of the species that breed on the extensive salt-marshes in
+many regions is a larger and more difficult problem, but as it is a
+matter that usually concerns large communities, sometimes whole states,
+it can be dealt with on a larger scale. The very excellent results that
+have been accomplished in New Jersey and on the San Francisco peninsula,
+and in a smaller way in other places, show what may be done if the
+community goes about the fight in an intelligent manner. In the fight in
+New Jersey hundreds of acres of tide-lands have been drained so that
+they no longer have tide pools standing where the mosquitoes may breed.
+When it is impracticable to drain them the pools may be sprayed
+occasionally with kerosene.</p>
+
+<p>The value of the land that is reclaimed by a good system of draining is
+often enough to pay many times over the cost of draining, thus the
+mosquitoes are gotten rid of and the land enhanced in value by a single
+operation.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_106" id="Page_106">[Pg 106]</a></span></p>
+<h2><a name="CHAPTER_VII" id="CHAPTER_VII"></a>CHAPTER VII</h2>
+
+<h3>MOSQUITOES AND MALARIA</h3>
+
+<div class="figdrop">
+<img src="images/drope.jpg" width="75" height="76" alt="drope" title="" />
+</div>
+<p class="noin"><span class="caps">ver</span> since the beginning of history we have records of certain fevers
+that have been called by different names according to the people that
+were affected. As we study these names and the various writings
+concerning the fevers we find that a great group of the most important
+of them are what we to-day know as malarial fevers. Not only are these
+ills as old as history but they have been observed over almost the
+entire inhabited earth. There are certain regions in all countries where
+malaria does not occur, but almost always it will be found that other
+regions near by are infected and it very often happens that these
+infected regions are the most profitable parts of the land, the places
+where water is plentiful and vegetation is luxuriant. Indeed the
+coincidence of these two things, low-lying lands with an abundance of
+water, particularly standing water, and malaria has always been noted
+and gave rise to the earliest theories in regard to the cause of the
+disease.</p>
+
+<p><span class='pagenum'><a name="Page_107" id="Page_107">[Pg 107]</a></span></p><p>For instance, we find some of the very early writers emphasizing the
+point that swampy localities should be avoided for they produce animals
+that give rise to disease, or that the air is poisoned by the breath of
+the swamp-inhabiting animals.</p>
+
+<p>These views of the origin of the fever prevailed until about the
+beginning of the eighteenth century when the recently discovered
+microscope began to reveal the various kinds of animalcul&aelig; to be found
+in decaying material.</p>
+
+<p>In 1718 Lancisi held that the myriads of insects, particularly gnats or
+mosquitoes, that arose from such swampy regions might carry some of
+these poisonous substances and by means of their proboscis introduce
+them into the bodies of the people, and although he had made no
+experiments to test the assumption he did not consider it impossible
+that such insects might also introduce the smallest animalcul&aelig; into the
+blood. It took almost two centuries of study and investigation before
+this guess was proved to be right.</p>
+
+<p>One reason why the mosquitoes were not earlier associated with these
+diseases was that all who investigated the matter at all turned their
+attention to the bad condition of the air in these swampy regions.
+Malaria means bad air. We all know that we can see the mists arising
+from such regions,<span class='pagenum'><a name="Page_108" id="Page_108">[Pg 108]</a></span> particularly in the evening or at night, and as
+exposure to these mists very often meant an attack of malaria they were
+naturally supposed to be the cause of the disease. So for a long time
+the whole attention of investigators was turned toward studying and
+analyzing these vapors, and various experiments were made which seemed
+to show conclusively that the malaria was caused only by these
+emanations. The investigations even went so far that the exact germs
+that were supposed to cause the fever were separated and experimented
+with.</p>
+
+
+<p class="center">THE PARASITE THAT CAUSES MALARIA</p>
+
+<p>The blood had been studied time and again and the characteristic
+appearance of the blood of a malarial patient was well known. In 1880
+Laveran, a French army surgeon in Algiers, began to study the blood of
+such patients microscopically and soon was able to demonstrate the
+parasite that caused the disease. His discoveries were not readily
+accepted, but other investigations soon confirmed his observations and
+the fact was gradually firmly established. Not until recently, however,
+did this distinguished physician receive a full recognition of his work.
+A few years ago he was awarded the Nobel prize for medicine, perhaps the
+highest honor that can be bestowed on any physician. It is interesting,
+too, to note in this connection that it was another French surgeon who
+in 1840 discovered that sulphate of quinine is a specific for malaria.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_96" id="Fig_96"></a>
+<img src="images/fig96.jpg" width="400" height="207" alt="Fig. 96" title="" />
+<span class="caption"><span class="smcap">Fig. 96</span>&mdash;Horse and cattle tracks in mud filled with
+water; good breeding-places for Anopheles.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_97" id="Fig_97"></a>
+<img src="images/fig97.jpg" width="400" height="399" alt="Fig. 97" title="" />
+<span class="caption"><span class="smcap">Fig. 97</span>&mdash;A malarial mosquito (<i>Anopheles maculipennis</i>); male.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_98" id="Fig_98"></a>
+<img src="images/fig98.jpg" width="400" height="328" alt="Fig. 98" title="" />
+<span class="caption"><span class="smcap">Fig. 98</span>&mdash;A malarial mosquito (<i>A. maculipennis</i>); female.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_109" id="Page_109">[Pg 109]</a></span></p><p>The next important step was made in 1885 by Golgi, an Italian, who
+studied the life-history of the parasite in the blood and distinguished
+the three forms which cause the three most familiar kinds of malarial
+fevers, the tertian, the quartan and the remittent types. From this time
+on this parasite has been studied by physicians of many nationalities
+and the whole course of its life-history worked out. In order that we
+may understand how it was that mosquitoes were determined to be the
+means of disseminating this parasite we will discuss first its
+life-history in the human blood.</p>
+
+<p>The parasites that cause the malarial fevers are Sporozoans and belong
+to the genus <i>Plasmodium</i>. Other names such as <i>H&aelig;mam&#339;ba</i> and
+<i>Laverania</i> have been used for them, but the term <i>Plasmodium</i> is the
+one now most commonly employed. The three most common species are
+<i>vivax</i>, <i>malari&aelig;</i> and <i>falciparum</i>, causing respectively the tertian,
+quartan and remittent fevers.</p>
+
+
+<p class="center">LIFE-HISTORY OF PARASITE</p>
+
+<p>The life-history of all of these is very similar, the principal
+difference being in the length of time it<span class='pagenum'><a name="Page_110" id="Page_110">[Pg 110]</a></span> takes them to sporulate. Let
+us begin with the parasite after it has been introduced into the blood
+and trace its development there. At first it is slender and rod-like in
+shape. It has some power of movement in the blood-plasm. Very soon it
+attacks one of the red blood-corpuscles and gradually pierces its way
+through the wall and into the corpuscle substance (<a href="#Fig_99">Fig. 99</a>); here it
+becomes more am&#339;boid and continues to move about, feeding all the
+time on the corpuscle substance, gradually destroying the whole cell. As
+the parasite feeds and grows there is deposited within its body a
+blackish or brownish pigment known as melanin.</p>
+
+<p>During the time that the parasite is feeding and growing it is also
+giving off waste products, as all living forms do in the process of
+metabolism, but as the parasite is completely inclosed in the corpuscle
+wall these waste products cannot escape until the wall bursts open.
+After about forty hours if the parasite is <i>vivax</i> or about sixty-five
+hours if it is <i>malari&aelig;</i> it becomes immobile, the nucleus divides again
+and again and the protoplasm collects around these nuclei, forming a
+number of small cells or spores, as they are called. In about
+forty-eight or seventy-two hours, depending on whether the parasite is
+<i>vivax</i> or <i>malari&aelig;</i> the wall of the corpuscle bursts and all these
+spores with the black pigment and the waste products that have been
+stored away within the cell are liberated into the blood-plasm.</p>
+
+<div class="figcenter" style="width: 600px;"><a name="Fig_99" id="Fig_99"></a>
+<img src="images/fig99.jpg" width="600" height="847" alt="Fig. 99" title="" />
+<span class="caption"><span class="smcap">Fig. 99</span>&mdash;Diagram to illustrate the life-history of the
+malarial parasite. 1 is a red blood-corpuscle, 2 to 7 shows the
+development of the parasite in the corpuscle, <i>a b c d</i> and <i>a&acute;
+b&acute; c&acute;</i> and <i>e</i> the development of the parasite in the stomach of the
+mosquito, <i>f g h i</i> the development in the capsule on the outer
+wall of the stomach of the mosquito, <i>k</i> in the salivary gland.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_100" id="Fig_100"></a>
+<img src="images/fig100.jpg" width="400" height="477" alt="Fig. 100" title="" />
+<span class="caption"><span class="smcap">Fig. 100</span>&mdash;Malarial mosquito (<i>A. maculipennis</i>) on the wall.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_101" id="Fig_101"></a>
+<img src="images/fig101.jpg" width="400" height="233" alt="Fig. 101" title="" />
+<span class="caption"><span class="smcap">Fig. 101</span>&mdash;Malarial mosquito (<i>A. maculipennis</i>) standing on a table.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_111" id="Page_111">[Pg 111]</a></span></p><p>These spores are round or somewhat am&#339;boid and are carried in the
+blood for a short time. Very soon, however, each one attacks a new red
+corpuscle and the process of feeding, growth and spore-formation
+continues, taking exactly the same time for development as in the first
+generation, so every forty-eight hours in the case of the <i>vivax</i>, and
+every seventy-two hours in the case of the <i>malari&aelig;</i> a new lot of these
+spores and the accompanying waste products are thrown out into the
+blood. Thus in a very short time many generations of this parasite occur
+and thousands or hundreds of thousands of the red-blood corpuscles are
+destroyed, leaving the patient weak and anemic. It will be seen, too,
+that the recurrence of the chills and fevers is simultaneous with the
+escaping of the parasites from the blood-corpuscles, together with the
+waste products of their metabolism.</p>
+
+<p>These waste products are poisonous, and it is believed that this great
+amount of poison poured into the blood at one time causes the regular
+recurring crisis. Zo&ouml;logists well know that this process of asexual
+reproduction, <i>i. e.</i>, reproduction without any conjugation of two
+different cells, cannot go on indefinitely, and those who were studying
+the life-cycle<span class='pagenum'><a name="Page_112" id="Page_112">[Pg 112]</a></span> of these parasites were at a loss to know where the
+sexual stage took place. In the meantime studies of other parasites more
+or less closely related to <i>Plasmodium</i> showed that the sexual stage
+occurred outside the vertebrate host. The remarkable work of Dr. Smith
+on the life-history of the germ that causes the Texas fever of cattle
+had a strong influence in directing the search for this other stage of
+the malarial parasite. Another thing that indicated that this sexual
+generation must take place outside the body of the vertebrate host was
+the fact that the investigators found that the parasites in certain of
+the cells did not sporulate as did the others. When these individuals
+were drawn from the circulation and placed on a slide for study it was
+found that they would swell up and free themselves from the inclosing
+corpuscle and some of them would emit long filaments which would dart
+away among the corpuscles.</p>
+
+<p>Many men have worked on this problem, but perhaps the most credit for
+its solution will always be given to Sir Patrick Manson, the foremost
+authority on tropical diseases, and to Ronald Ross, a surgeon in the
+English army. There is no more interesting and inspiring reading than
+that which deals with the development of the hypothesis by Manson and
+the persistent faith of Ross in the<span class='pagenum'><a name="Page_113" id="Page_113">[Pg 113]</a></span> correctness of this theory, and his
+continuous indefatigable labors in trying to demonstrate it. It was an
+important piece of scientific work, and shows what a man can do even
+when the obstacles seem insurmountable.</p>
+
+
+<p class="center">THE PARASITE IN THE MOSQUITO</p>
+
+<p>Briefly stated again, the problem was this: We have here a parasite in
+the blood which behaves as do many other forms of life. Some of these
+parasites do not go on with their development until they are removed
+from the circulation. Now, how are they thus removed from the
+circulation under normal conditions? This must first be solved before
+the still greater and more important problem of how the parasite gets
+from one human host to another can be taken up. In studying this over
+Manson reasoned that certain suctorial insects were the agencies through
+which blood was most commonly removed from the circulation and he
+ventured the guess that this change in the parasite that may be seen
+taking place on the slide under the microscope, normally takes place in
+the stomach of some insect that sucks man's blood. Ross was greatly
+impressed with the theory and began his long and apparently hopeless
+task of finding these parasites in the stomach of some insect.<span class='pagenum'><a name="Page_114" id="Page_114">[Pg 114]</a></span> When we
+remember that they are so minute that they can only be seen by the use
+of the highest power of the microscope we can realize something of the
+magnitude of the task. Ross, who was at that time stationed in India,
+selected the mosquito as the most likely of the insects to be the host
+that he was looking for. For over two and one-half years he worked with
+entirely negative results, for after examining thoroughly many thousands
+of mosquitoes he found no trace of the parasite.</p>
+
+<p>Practically all his work was done on the most common mosquito of the
+region, a species of <i>Culex</i>. But one day a friend sent him a different
+mosquito, one with spotted wings, and in examining it he was interested
+to note certain oval or round nodules on the outer walls of the stomach.
+On closer examinations he found that each of these nodules contained a
+few granules of the coal-black melanin of malarial fever. Further
+studies and experiments showed that these particular cells could always
+be found in the walls of the stomach of this particular species of
+mosquito a few days after it had bitten a malarial patient. This
+epoch-making discovery was made in 1898. Ross was detailed by the
+English government to devote his whole time to the further solution of
+the problem, and after two years more of careful experimentation and
+study<span class='pagenum'><a name="Page_115" id="Page_115">[Pg 115]</a></span> was able to give a complete life-history of this parasite. His
+experiments have been repeated many times, and the conclusions he
+arrived at are as undeniable as any of the known facts of science.</p>
+
+<p>The whole life-history as we now know it can be summed up as follows:
+The parasites develop within the circulation but certain of them seem to
+wander about and do not go on with their development there. When these
+particular parasites are taken into the stomach of most mosquitoes they
+are digested with the rest of the blood. But when they are taken into
+the stomach of a mosquito belonging to the genus <i>Anopheles</i> or other
+closely related genera they are not digested but go on with their
+development, conjugation and fertilization taking place, resulting in a
+more elongated form which makes its way through the walls of the stomach
+on the outside of which are formed the little nodules discovered by Ross
+on his mosquitoes. Within these nodules further division and development
+takes place until finally the nodule is burst open and many thousand
+minute rod-like organisms, sporozoites, are turned loose into the
+body-cavity of the mosquito. Owing to some unknown cause these little
+organisms are gathered together in the large vacuolated cells of the
+salivary glands of the mosquito, and when the mosquito bites a<span class='pagenum'><a name="Page_116" id="Page_116">[Pg 116]</a></span> man or
+any other animal they pour down through the ducts with the secretion and
+are thus again introduced in the circulation.</p>
+
+<p>The nodules or cysts on the walls of the stomach of the mosquito may
+contain as many as ten thousand sporozoites, and as many as five hundred
+cysts may occur on a single stomach.</p>
+
+<p>It takes ten, twelve or more days from the time the parasites are taken
+into the stomach of the mosquito before they can go through their
+transformations and reach the salivary gland, the time depending on the
+temperature. So it is ten or twelve days or sometimes as much as
+eighteen or twenty days from the time an <i>Anopheles</i> bites a malarial
+patient before it is dangerous or can spread the disease. On the other
+hand, the sporozoites may lie in the salivary gland alive and virulent
+for several weeks. It does not give up all the parasites at one time, so
+that three or four or more people may be affected by a single mosquito.</p>
+
+<p>It is well known that two parasites may often be seen in the same
+corpuscle. This is often simply a case of multiple infection, but Dr.
+Craig has very recently shown that under certain conditions two
+individuals may enter the same corpuscle and conjugate and the resulting
+individual will be resistant to quinine and may remain latent in the
+spleen or<span class='pagenum'><a name="Page_117" id="Page_117">[Pg 117]</a></span> bone marrow for a long time. Under favorable conditions it
+may again begin the process of multiplication and the patient will
+suffer a relapse.</p>
+
+
+<p class="center">SUMMARY</p>
+
+<p>Now let us sum up some of the reasons why we believe that the malaria
+fever can be transmitted only through the agency of mosquitoes. First,
+we know the life-history of the parasite, it has been studied in both of
+its hosts. Attempts have been made to rear it in other hosts but without
+avail, and we know from the general relations of the parasite that it
+must have this sexual as well as the asexual generations. Second, in
+some regions which would seem to be malarial, that is, where the
+miasmatic mists arise, no malaria occurs. Why? Usually it can be
+definitely shown that no <i>Anopheles</i> occur there. Other mosquitoes may
+be there in abundance, but if no <i>Anopheles</i>, there is no malaria. In
+certain regions this is well demonstrated. The west coast of Africa is
+one of the worst pest-holes of malaria and <i>Anopheles</i>. The east coast
+has no malaria and no <i>Anopheles</i>. In many islands the same condition
+exists. On the other hand, the Fiji Islands have <i>Anopheles</i> but no
+malaria. No malaria has ever been introduced there to infect the
+mosquitoes. In the same way<span class='pagenum'><a name="Page_118" id="Page_118">[Pg 118]</a></span> <i>Stegomyia</i> occurs in some of the South Sea
+islands and yet there is no yellow fever there.</p>
+
+
+<p class="center">EXPERIMENTS</p>
+
+<p>We may review, too, a few of the classic experiments that have served to
+show that malaria can be contracted in no other way than through the
+bite of the mosquito.</p>
+
+<p>For many years Grassi, an Italian, devoted almost his whole time to the
+study of malaria. In 1900 he received permission from the government to
+experiment on the employees of a piece of railroad that was being built
+through a malarial region. This was divided for the purpose of the
+experiment into three sections, a protected zone in the middle and an
+unprotected zone at each end.</p>
+
+<p>Those working in the protected zone had their houses completely screened
+and no one was allowed out of doors after sunset except they were
+protected with veils and gloves. Early in the season they were all given
+doses of quinine to prevent auto-infection. In the unprotected zone no
+screens were used and every one was allowed to go without special
+protection. The result for the summer was that there were no new cases
+of fever in the protected zone. In the unprotected zones practically all
+had the fever as usual.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_102" id="Fig_102"></a>
+<img src="images/fig102.jpg" width="400" height="200" alt="Fig. 102" title="" />
+<span class="caption"><span class="smcap">Fig. 102</span>&mdash;Salt-marsh mosquito (<i>O. lativittatus</i>) standing on a table.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_103" id="Fig_103"></a>
+<img src="images/fig103.jpg" width="400" height="421" alt="Fig. 103" title="" />
+<span class="caption"><span class="smcap">Fig. 103</span>&mdash;Anopheles hanging from the ceiling.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_119" id="Page_119">[Pg 119]</a></span></p><p>In the same year two English physicians, Sambon and Low, went to Italy
+where they built a cabin in one of the marshes noted as being a malaria
+pest-hole. The house was thoroughly screened so that no mosquitoes could
+enter, but the windows were always open so as to admit the air freely
+day and night. Here they lived for three months, out of doors as much as
+they pleased during the day but inside where they were protected from
+the mosquitoes at night. No quinine was used and no fever developed,
+although all about them other people were having the fever as usual.</p>
+
+<p>Another English physician who had not been in malarial regions allowed
+himself to be bitten by infected mosquitoes sent from a malarial
+locality. In due time he developed the fever. Many other experiments
+made in various places might be cited. The results have all been
+practically the same. To-day the soldiers of many civilized nations are
+required to protect themselves from mosquitoes because it has been found
+that it pays. Disease has always been a worse terror than bullets in any
+war, and we are fast learning that the great loss from diseases
+heretofore considered unavoidable may be very largely eliminated by
+proper sanitary arrangements and protection from noxious insects.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_120" id="Page_120">[Pg 120]</a></span></p>
+<h2><a name="CHAPTER_VIII" id="CHAPTER_VIII"></a>CHAPTER VIII</h2>
+
+<h3>MOSQUITOES AND YELLOW FEVER</h3>
+
+<div class="figdrop">
+<img src="images/dropy.jpg" width="75" height="77" alt="dropy" title="" />
+</div>
+<p class="noin"><span class="caps">ellow</span> fever is a disease, principally of seaport towns, from which the
+United States has suffered more than any other country. It is endemic
+only in tropical regions but is often carried to subtropical, sometimes
+even to temperate zones where, if the proper mosquitoes exist, it may
+rage until frost.</p>
+
+<p>Vera Cruz, Havana, Rio de Janeiro, and the west coast of Africa were
+long regarded as permanent endemic foci, the disease appearing there in
+epidemic form from time to time, often spreading to other ports in more
+or less close communication with such places. In the United States the
+Gulf states have been the greatest sufferers from the disease, although
+it has spread as far as Baltimore, Philadelphia and Washington, where at
+rare intervals it was most serious, abating its ravages only when frost
+came.</p>
+
+<p>The last severe outbreak occurred in New Orleans in 1905 when eight
+thousand cases and nine<span class='pagenum'><a name="Page_121" id="Page_121">[Pg 121]</a></span> hundred deaths occurred. At that time there was
+waged one of the most remarkable warfares against death in its most
+terrifying form that the world has ever known. And, thanks to the
+achievements of science, particularly to the investigations of three
+men, one of whom gave his life to the cause, the fight was successful
+and this dreadful outbreak was checked just at the time when according
+to all precedent it should have been at its height.</p>
+
+<p>This result which at other times and under other conditions would have
+been considered miraculous was achieved not by the usual custom of
+isolation, quarantine, etc., but by a direct, we may almost say hand to
+hand, conflict with mosquitoes: the mosquitoes belonging to a particular
+genus and species, <i>Stegomyia calopus</i> (<i>fasciata</i>).</p>
+
+<p>Before taking up a discussion of this achievement in New Orleans let us
+consider first the work of the men that made such results possible.</p>
+
+<p>For many years the cause and methods of dissemination of this disease
+had been a puzzle to physicians and scientists. Very early it was
+believed that it might be transmitted through the air, and the fact that
+infection usually occurred in the vicinity of the water and in the
+tropics or in midsummer led to the belief that the disease was due to
+fermentation. This theory received strong<span class='pagenum'><a name="Page_122" id="Page_122">[Pg 122]</a></span> support in the fact that
+serious outbreaks of the fever often followed the coming into port of
+vessels from the tropics with the water in their holds in an offensive
+condition. When it was discovered that bacteria were the cause of
+fermentation and also of many diseases this theory was considered
+abundantly proven. From time to time, announcements have been made that
+the particular species of bacteria that causes the disease has been
+isolated, but there has always been something lacking in the final
+proof.</p>
+
+<p>Yellow fever has always been regarded as a very highly contagious as
+well as infectious disease, and the utmost precaution has been taken to
+isolate the patients when possible and in recent years strict
+quarantines have been established against infected localities and no
+person or commerce or even the mails were allowed to come from such
+places without thorough fumigations. But all these things proved
+unsatisfactory. The disease could not ordinarily be checked by simply
+isolating the patients. Many people became sick without ever having been
+near a yellow fever patient, while others worked in direct daily contact
+with the disease and did not suffer from it. Those who had once had it
+and recovered became practically immune, rarely suffering from a second
+attack. Negroes may suffer from the disease, but are usually regarded as
+practically immune.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_104" id="Fig_104"></a>
+<img src="images/fig104.jpg" width="400" height="659" alt="Fig. 104" title="" />
+<span class="caption"><span class="smcap">Fig. 104</span>&mdash;Yellow-fever mosquito (<i>Stegomyia calopus</i>). (R. Newstead, del.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_123" id="Page_123">[Pg 123]</a></span></p><p>It was early observed, too, that the danger zone might be quite well
+defined and that outside this zone one would be safe. More than a
+century ago the British troops and other inhabitants of Jamaica found
+that by retreating to the mountains during the warm weather the
+non-immunes could escape the fever. It was also observed that those who
+slept on the first floor were more apt to take the disease than those on
+the second floor.</p>
+
+
+<p class="center">THE YELLOW FEVER COMMISSION</p>
+
+<p>In 1900, during the American occupation of Cuba, yellow fever became
+very prevalent there. A board of medical officers was ordered to meet in
+Havana for the purpose of studying the disease under the favorable
+opportunities thus afforded. This board, which came to be known as the
+Yellow Fever Commission, was composed of Drs. Walter Reed, James
+Carroll, Jessie W. Lazear and Aristides Agramonte of the United States
+Army. Agramonte was a Cuban and an immune, the others were non-immunes.
+Dr. Manson in his lectures on Tropical Medicines says of them:</p>
+
+<div class="blockquot"><p>"I cannot pass on, however, to what I have to say in connection
+with this work without a word of admiration<span class='pagenum'><a name="Page_124" id="Page_124">[Pg 124]</a></span> for the insight, the
+energy, the skill, the courage, and withal the modesty and
+simplicity of the leader of that remarkable band of workers. If any
+man deserved a monument to his memory, it was Reed. If any band of
+men deserve recognition at the hands of their countrymen, it is
+Reed's colleagues." </p></div>
+
+<p>Their first work was to determine whether any of the germs that had been
+claimed to be the cause of yellow fever were really responsible for the
+disease. <i>Bacillus icteroides</i> that for some time and by some
+investigators had been named as the offender was particularly
+investigated, but was proved to be a secondary invader only.</p>
+
+<p>Dr. Charles Finlay of Havana had been claiming for some years that the
+yellow fever was transmitted by means of the mosquito and possibly by
+other insects also. He even claimed to have proved this theory
+experimentally. We know now, however, that there must have been errors
+in his experiments and that his patients became infected from sources
+other than those he was dealing with.</p>
+
+<p>The Yellow Fever Commission decided to put this theory to the test and
+secured a number of volunteers for the experiments. The first thing was
+to let an infected mosquito bite some non-immune person. How this was
+done and the results, may be told in Dr. Carroll's own words.</p>
+
+
+<p><span class='pagenum'><a name="Page_125" id="Page_125">[Pg 125]</a></span></p><p class="center">EXPERIMENTS</p>
+
+<div class="blockquot"><p>"Two separate lines of work now presented: one, the study of the
+bacterial flora of the intestine and ana&euml;robic cultures from the
+blood and various organs; the other, the theory of the transmission
+of the disease by the mosquito, which had been advanced by Dr.
+Carlos Finlay in 1881. After due consideration it was decided to
+investigate the latter first. Then arose the question of the
+tremendous responsibility involved in the use of human beings for
+experimental purposes. It was concluded that the results
+themselves, if positive, would be sufficient justification of the
+undertaking. It was suggested that we subject ourselves to the same
+risk and this suggestion was accepted by Dr. Reed and Dr. Lazear.
+It became necessary for Dr. Reed to return to the United States and
+the work was begun by Dr. Lazear, who applied infected mosquitoes
+to a number of persons, himself included, without result. On the
+afternoon of July 27, 1900, I submitted myself to the bite of an
+infected mosquito applied by Dr. Lazear. The insect had been reared
+and hatched in the laboratory, had been caused to feed upon four
+cases of yellow fever, two of them severe, and two mild. The first
+patient, a severe case, was bitten twelve days before; the second,
+third and fourth patients had been bitten six, four and two days
+previously, and were in character mild, severe and mild
+respectively. In writing to Dr. Reed that night of the incident, I
+remarked<span class='pagenum'><a name="Page_126" id="Page_126">[Pg 126]</a></span> jokingly that if there was anything in the mosquito
+theory, I should have a good dose. And so it happened. After having
+slight premonitory symptoms for two days, I was taken sick on
+August 31, and on September 1, I was carried to the yellow fever
+camp. My life was in the balance for three days, and my chart shows
+that on the fifth, sixth and seventh days my urine contained
+eighth-tenths and nine-tenths of moist albumin. On the day I was
+taken sick, August 31, 1900, Dr. Lazear applied the same mosquito,
+with three others, to another individual who suffered a
+comparatively mild attack and was well before I had left my bed. It
+so happened that I was the first person in whom the mosquito was
+proved to convey the disease.</p>
+
+<p>"On the eighteenth of September, five days after I was permitted to
+leave my bed, Dr. Lazear was stricken, and died in convulsions just
+one week later, after several days of delirium with black vomit.
+Such is yellow fever.</p>
+
+<p>"He was bitten by a stray mosquito while applying the other insects
+to a patient in one of the city hospitals. He did not recognize it
+as a <i>Stegomyia</i>, and thought it was a <i>Culex</i>. It was permitted to
+take its fill and he attached no importance to the bite until after
+he was taken sick, when he related the incident to me. I shall
+never forget the expression of alarm in his eyes when I last saw
+him alive in the third or fourth day of his illness. The spasmodic
+contractions of his diaphragm indicated that black vomit was
+impending, and<span class='pagenum'><a name="Page_127" id="Page_127">[Pg 127]</a></span> he fully appreciated their significance. The
+dreaded vomit soon appeared. I was too weak to see him again in
+that condition, and there was nothing that I could do to help him.</p>
+
+<p>"Dr. Lazear left a wife and two young children, one of whom he had
+never seen." </p></div>
+
+<p>These experiments and many others like them conducted on soldiers and
+Spanish immigrants proved that this particular mosquito would transmit
+the disease under certain conditions.</p>
+
+<p>1. The mosquito must bite the patient during the first three days of the
+fever; after that a yellow fever patient cannot infect a mosquito.</p>
+
+<p>2. A period of twelve days must elapse before the mosquito is able to
+infect another person. After that she may infect anyone she may bite;
+that is, the germs remain virulent during the rest of the mosquito's
+life. The French Yellow Fever Commission working in Rio de Janeiro claim
+that the first generation of offspring from such an infected mosquito is
+capable of causing the disease after they are fourteen days in the adult
+condition.</p>
+
+<p>The next step was to ascertain whether the disease could be contracted
+in any other way than by the bites of infected mosquitoes. A camp named
+Camp Lazear was established and the following tests made: A
+mosquito-proof building of one room<span class='pagenum'><a name="Page_128" id="Page_128">[Pg 128]</a></span> was completely divided by a wire
+screen from floor to ceiling. In one room fifteen mosquitoes that had
+previously bitten yellow fever patients and had undergone the proper
+period of incubation were liberated. In this room a non-immune exposed
+himself so that he was bitten by several of the insects. A little later
+the same day and again the next day the mosquitoes were allowed to feed
+on him for a few minutes. Five days later, the usual incubation period,
+he developed yellow fever.</p>
+
+<p>At the same time that he entered the building two other non-immunes
+entered the other compartment where they slept for eighteen nights
+separated from the mosquitoes by the wire screen. They showed no signs
+of taking the fever.</p>
+
+<p>In another mosquito-proof house two soldiers and a surgeon, all
+non-immunes, lived for twenty-one days. From time to time they were
+supplied with soiled articles of bedding, clothing, etc., direct from
+the yellow fever hospital in the city. These articles had been soiled by
+the urine, fecal matter and black vomit obtained from fatal and other
+cases of yellow fever. These articles were handled and shaken daily, but
+no disease developed among the men and at the end of the twenty-one
+days, two other non-immunes relieved them and handled a new supply of
+clothing in the same way,<span class='pagenum'><a name="Page_129" id="Page_129">[Pg 129]</a></span> sleeping between the same sheets that had
+been used by a patient dying of yellow fever and exposing themselves in
+every possible way to the soiled clothing. But no disease developed.
+That these men were susceptible was shown later by inoculating some of
+them, when they developed the disease.</p>
+
+<p>In another experiment certain men in a camp allowed themselves to be
+bitten by mosquitoes that had passed through the proper period of
+incubation and every one of them and no others contracted the disease.
+It was also shown that a mosquito was capable of communicating the
+disease as long as fifty-seven days after it had bitten a yellow fever
+patient. Another set of experiments showed that a subcutaneous injection
+into a non-immune of a very small quantity of blood from the veins of a
+yellow fever patient in the first two or three days of the disease would
+produce the fever.</p>
+
+
+<p class="center">SUMMARY OF RESULTS</p>
+
+<p>Since that time much other work has been done by independent workers as
+well as by French and English Commissions both working at Rio de
+Janeiro. The results of their investigation are practically the same and
+may be summed up as follows:</p>
+
+<p><span class='pagenum'><a name="Page_130" id="Page_130">[Pg 130]</a></span></p><p>1. The virus of the yellow fever is in the blood-plasma, not in the
+corpuscles, for these may be removed and the plasma still be infective.</p>
+
+<p>2. The virus is conveyed from one patient to another by the yellow fever
+mosquito, <i>Stegomyia calopus</i>, and in no other way except by
+experimental injections.</p>
+
+<p>3. The patient is a source of infection only during the first three or
+four days of the disease (this after the three to six days of
+incubation).</p>
+
+<p>4. The virus must undergo an incubation period of twelve to fourteen
+days in the mosquito before she is capable of transmitting the disease.</p>
+
+<p>5. The parasite, whatever it is, has never been seen. It is probably too
+small to be seen by any of our present microscopes, even the recently
+invented ultramicroscope. It is probably not a bacterial parasite but
+very likely a Protozoan, and certain specialists have even shown by the
+study of all the available data that it almost certainly belongs to the
+Sporozoan genus <i>Spirocheta</i>.</p>
+
+<p>Now what does all this mean? It means the saving of hundreds of human
+lives annually. It means the banishing from many localities and possibly
+very soon from the face of the earth of a disease that since the
+earliest settlements on this continent has been a source of terror. It
+means<span class='pagenum'><a name="Page_131" id="Page_131">[Pg 131]</a></span> the making habitable of certain places which heretofore a white
+man has entered only at the risk of his life. It means that quarantines
+need no longer be established when yellow fever breaks out in a
+district; quarantines which have inevitably caused the loss of millions
+of dollars to the world of commerce.</p>
+
+
+<p class="center">RESULTS IN HAVANA</p>
+
+<p>The first practical work based on these findings was done in Havana. The
+Yellow Fever Commission made their recommendations in 1900. In 1901 and
+1902 they were put into effect. The following table of the death rate
+there during a period of ten years shows graphically the results:</p>
+
+<p class="center">DEATHS IN HAVANA FROM YELLOW FEVER</p>
+
+<div class='center'>
+<table border="0" cellpadding="4" cellspacing="0" summary="Deaths in Havana from Yellow Fever">
+<tr class='tr3'>
+ <td class='tdcbr'>&nbsp;</td>
+ <td class='tdcbr'>1893</td>
+ <td class='tdcbr'>1894</td>
+ <td class='tdcbr'>1895</td>
+ <td class='tdcbr'>1896</td>
+ <td class='tdcbr'>1897</td>
+ <td class='tdcbr'>1898</td>
+ <td class='tdcbr'>1899</td>
+ <td class='tdcbr'>1900</td>
+ <td class='tdcbr'>1901</td>
+ <td align='center'>1902</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Jan.</td>
+ <td class='tdrbr'>15</td>
+ <td class='tdrbr'>7</td>
+ <td class='tdrbr'>15</td>
+ <td class='tdrbr'>10</td>
+ <td class='tdrbr'>69</td>
+ <td class='tdrbr'>7</td>
+ <td class='tdrbr'>1</td>
+ <td class='tdrbr'>8</td>
+ <td class='tdrbr'>7</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Feb.</td>
+ <td class='tdrbr'>6</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>7</td>
+ <td class='tdrbr'>24</td>
+ <td class='tdrbr'>1</td>
+ <td class='tdrbr'>0</td>
+ <td class='tdrbr'>9</td>
+ <td class='tdrbr'>5</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Mar.</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>3</td>
+ <td class='tdrbr'>30</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>1</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>1</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Apr.</td>
+ <td class='tdrbr'>8</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>6</td>
+ <td class='tdrbr'>14</td>
+ <td class='tdrbr'>71</td>
+ <td class='tdrbr'>1</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>0</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>May</td>
+ <td class='tdrbr'>23</td>
+ <td class='tdrbr'>16</td>
+ <td class='tdrbr'>10</td>
+ <td class='tdrbr'>27</td>
+ <td class='tdrbr'>88</td>
+ <td class='tdrbr'>4</td>
+ <td class='tdrbr'>0</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>June</td>
+ <td class='tdrbr'>69</td>
+ <td class='tdrbr'>31</td>
+ <td class='tdrbr'>16</td>
+ <td class='tdrbr'>46</td>
+ <td class='tdrbr'>174</td>
+ <td class='tdrbr'>3</td>
+ <td class='tdrbr'>1</td>
+ <td class='tdrbr'>8</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>July</td>
+ <td class='tdrbr'>118</td>
+ <td class='tdrbr'>77</td>
+ <td class='tdrbr'>88</td>
+ <td class='tdrbr'>116</td>
+ <td class='tdrbr'>168</td>
+ <td class='tdrbr'>16</td>
+ <td class='tdrbr'>2</td>
+ <td class='tdrbr'>30</td>
+ <td class='tdrbr'>1</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Aug.</td>
+ <td class='tdrbr'>100</td>
+ <td class='tdrbr'>73</td>
+ <td class='tdrbr'>120</td>
+ <td class='tdrbr'>262</td>
+ <td class='tdrbr'>102</td>
+ <td class='tdrbr'>16</td>
+ <td class='tdrbr'>13</td>
+ <td class='tdrbr'>49</td>
+ <td class='tdrbr'>2</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Sep.</td>
+ <td class='tdrbr'>68</td>
+ <td class='tdrbr'>76</td>
+ <td class='tdrbr'>135</td>
+ <td class='tdrbr'>166</td>
+ <td class='tdrbr'>56</td>
+ <td class='tdrbr'>34</td>
+ <td class='tdrbr'>18</td>
+ <td class='tdrbr'>52</td>
+ <td class='tdrbr'>2</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Oct.</td>
+ <td class='tdrbr'>46</td>
+ <td class='tdrbr'>40</td>
+ <td class='tdrbr'>102</td>
+ <td class='tdrbr'>240</td>
+ <td class='tdrbr'>42</td>
+ <td class='tdrbr'>26</td>
+ <td class='tdrbr'>25</td>
+ <td class='tdrbr'>74</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+<tr>
+ <td class='tdlbr'>Nov.</td>
+ <td class='tdrbr'>28</td>
+ <td class='tdrbr'>23</td>
+ <td class='tdrbr'>35</td>
+ <td class='tdrbr'>244</td>
+ <td class='tdrbr'>26</td>
+ <td class='tdrbr'>13</td>
+ <td class='tdrbr'>18</td>
+ <td class='tdrbr'>54</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+<tr class='tr4'>
+ <td class='tdlbr'>Dec.</td>
+ <td class='tdrbr'>11</td>
+ <td class='tdrbr'>29</td>
+ <td class='tdrbr'>20</td>
+ <td class='tdrbr'>147</td>
+ <td class='tdrbr'>8</td>
+ <td class='tdrbr'>13</td>
+ <td class='tdrbr'>22</td>
+ <td class='tdrbr'>20</td>
+ <td class='tdrbr'>0</td>
+ <td align='right'>0</td>
+</tr>
+</table></div>
+
+<p><span class='pagenum'><a name="Page_132" id="Page_132">[Pg 132]</a></span></p><p>As long as the United States held control at Havana the yellow fever
+was kept in check by fighting the mosquitoes, when this vigilance was
+relaxed the fever began to appear again and the Cubans found that it was
+necessary to keep up the fight against the mosquitoes if the island was
+to be kept free from the disease.</p>
+
+
+<p class="center">THE FIGHT IN NEW ORLEANS</p>
+
+<p>In the summer of 1905 came another opportunity to put the knowledge
+gained during these experiments to a practical test. Samuel Hopkins
+Adams in his article in <i>McClure's Magazine</i>, June, 1906, says of the
+beginning of this fight:</p>
+
+<div class="blockquot"><p>"Eight years before, the mosquito-plague had infected the great,
+busy, joyous metropolis of the south. Ignorant of the real
+processes of the infection, New Orleans had fought it blindly,
+frantically, in an agony of panic, and when at last the frost put
+an end to the helpless city's plight, she lay spent and prostrate.
+The yellow fever of 1905 came with a more formidable and unexpected
+suddenness than that of 1897. It sprang into life like a secret and
+armed uprising in the midst of the city, full-fledged and terrible.
+But there arose against it the trained fighting line of scientific
+knowledge. Accepting, with a fine courage of faith that most
+important preventive discovery since vaccination,<span class='pagenum'><a name="Page_133" id="Page_133">[Pg 133]</a></span> the mosquito
+dogma, the Crescent City marshaled her defenses. This time there
+was no panic, no mob-rule of terrified thousands, no mad rushing
+from stunned inertia to wildly impractical action; but instead the
+enlistment of the whole city in an army of sanitation. Every
+citizen became a soldier of the public health. And when, long
+before the plague-killing frost came, the battle was over, New
+Orleans had triumphed not only in the most brilliant hygienic
+victory ever achieved in America, but in a principle for which the
+whole nation owes her a debt of gratitude." </p></div>
+
+<p>For some time the authorities had been trying to keep secret the fact
+that the disease was prevalent, but the rapidity with which it spread
+made them realize that only united action on the part of all the
+community would be of any avail. The Citizens Volunteer Ward
+Organizations were organized for the purpose of fighting the mosquitoes
+which were everywhere. To many the fight looked hopeless. The miles of
+open gutters, the thousands of cisterns and little pools of standing
+water everywhere furnished abundant breeding-places for the mosquitoes.
+The ditches and ponds were drained or salted, the cisterns were
+screened, infected houses were fumigated, yet the fever continued to
+spread. Rains refilled the ditches, winds tore the screens from the
+cisterns, the ignorant<span class='pagenum'><a name="Page_134" id="Page_134">[Pg 134]</a></span> people of the French quarter refused to
+co&ouml;perate. At last the city in desperation appealed to the President for
+aid. Surgeon J.H. White and a number of officers and men of the United
+States Public Health and Marine Hospital Service soon took charge of the
+work. This was continued along the same lines as before with the same
+object in view. But with the coming of the regulars the work was more
+systematically and thoroughly done. Every case of fever was treated as
+though it was yellow fever and every precaution taken to prevent
+mosquitoes from biting such a patient. The houses in which the fever
+occurred were thoroughly fumigated to kill any mosquitoes that might be
+there, and the neighborhood was thoroughly searched to find any places
+where the mosquitoes might be breeding. So confident were the
+authorities that the mosquito was the sole cause of the disease
+spreading, that besides fighting it no other work was undertaken save to
+make the sick as comfortable as possible.</p>
+
+<p>Finally the results began to be apparent. The number of cases gradually
+diminished, until long before frost came the city was free from the
+great pest. Yellow fever will doubtless appear from time to time in New
+Orleans and other cities, but there is, at least there should be, small
+danger of<span class='pagenum'><a name="Page_135" id="Page_135">[Pg 135]</a></span> another great epidemic, for the people now know how the
+disease is caused and the remedy.</p>
+
+<p>Not long since I had occasion to write to a prominent entomologist in
+Louisiana for some specimens of the yellow fever mosquito for laboratory
+work. The following extract from his reply will show something of the
+work that is still being done there.</p>
+
+<div class="blockquot"><p>"I am afraid we cannot furnish specimens of <i>Stegomyia</i>, in spite
+of the fact that Louisiana is <i>supposed</i> to be the most favorable
+home of this species in the South. Since the light occurrence of
+yellow fever in this State in 1905, a very vigorous war has been
+kept up against <i>Stegomyia</i>, and the ordinances of all Louisiana
+cities and principal towns require the draining of all breeding
+places of this mosquito and the constant oiling or screening of all
+cisterns or other water containers. The result is this species is
+very rare. Here in Baton Rouge I only see one once in a great
+while, and it would require perhaps a good many days' work at the
+present season to get as good specimens and as many of them as you
+require." </p></div>
+
+
+<p class="center">IN THE PANAMA CANAL ZONE</p>
+
+<p>Yellow fever was one of the worst obstacles that confronted the French
+when they were attempting to build the Panama Canal. The story of the<span class='pagenum'><a name="Page_136" id="Page_136">[Pg 136]</a></span>
+suffering and death from this dread disease there is most pathetic.
+Ship-load after ship-load of laborers were sent over, as those who had
+gone earlier succumbed to the fever. The contractors were responsible
+for their men while they were sick and in order to avoid having to pay
+hospital expenses the men were often discharged as soon as they showed
+signs of sickness. Many of them died along the roadside while
+endeavoring to reach some place where they could obtain aid. The
+hospitals were usually filled with yellow fever patients, a very large
+percentage of whom died.</p>
+
+<p>Not only the day laborers suffered but many of the engineers, doctors,
+nurses and others sickened and died of the disease. It is reported that
+eighteen young French engineers came over on one vessel and in a month
+after their arrival all but one had died of the yellow fever. Out of
+thirty-six nurses brought over at one time, twenty-four died of the
+fever, and during one month nine members of the medical staff of one of
+the hospitals succumbed.</p>
+
+<p>One of the first things that the United States Government did in
+beginning work in the canal zone was to take up the fight against the
+yellow fever mosquito. In Panama where the water for domestic purposes
+was kept in cisterns and water-barrels, inspectors were appointed to see
+that all<span class='pagenum'><a name="Page_137" id="Page_137">[Pg 137]</a></span> such receptacles and other possible breeding-places for
+mosquitoes were kept covered. After the first inspection, 4,000
+breeding-places were reported. About six months later there were less
+than 400. Similar work was done in all the towns and settlements along
+the route of the canal. In addition to this fight against the yellow
+fever mosquito considerable attention was paid to the breeding-places of
+the malarial mosquito. The results have been remarkable. Cases of yellow
+fever are now rare throughout this zone, and there has been a very great
+reduction in the extent of the malarial districts. The last case of
+yellow fever occurred in May, 1906. Before this work was done a man took
+his life in his hands when he went into this region. Now it is regarded
+as a perfectly safe place to live. Indeed it is a much safer place than
+many sections of our own country where proper sanitary measures have not
+been taken to protect the health of the community.</p>
+
+
+<p class="center">IN RIO DE JANEIRO</p>
+
+<p>In Rio de Janeiro they have as yet been unable to get rid of the
+mosquitoes, although thousands of dollars are spent annually in fighting
+them. But the non-immunes there protect themselves by doing their
+business in Rio during the day and going back at night to Petropolis,
+twenty-five miles inland<span class='pagenum'><a name="Page_138" id="Page_138">[Pg 138]</a></span> and twenty-five hundred feet higher, where
+they are safe, for no <i>Stegomyia</i> have ever been found there.</p>
+
+<p>They claim there that the yellow fever mosquito does not bite during the
+daytime after she has laid her eggs, and that she will not lay her eggs
+until about three days after she has fed on blood, therefore a
+<i>Stegomyia</i> that bites during the day will not carry the yellow fever
+because she is too young. This seems to explain why the fever cannot be
+contracted by being bitten by a mosquito in the daytime. Certain other
+experiments, however, have given different results so that as far as we
+know it is not safe to be bitten at any time by such a mosquito in a
+region where the disease is endemic or where it is epidemic.</p>
+
+<p>In the main the work of the French Yellow Fever Commission working in
+Rio de Janeiro has confirmed the findings of the American Commission.
+One interesting special thing that the French Commission seems to have
+established is that the female may transmit the infecting power to her
+offspring, so that it would be possible for a mosquito that had never
+bitten a yellow fever patient to be capable of infecting a non-immune
+person. While all this is very probable in the light of what we know of
+the disease and the way in<span class='pagenum'><a name="Page_139" id="Page_139">[Pg 139]</a></span> which other diseases caused by similar
+organisms may be transmitted by the parent to the offspring, yet the
+most conservative investigators are waiting for further proof.</p>
+
+
+<p class="center">HABITS OF STEGOMYIA</p>
+
+<p>The whole fight against yellow fever, then is directed, as we have seen,
+against the mosquito, <i>Stegomyia calopus</i>. The habits of this species
+are such as to make it easy in some respects to combat. It is seldom
+found far away from human habitation. The adults will not fly far. Once
+in a house they usually stay there except when they leave to deposit
+their eggs.</p>
+
+<p>On the other hand, some of these same habits make it all the more
+dangerous. It will breed in almost any kind of water, no matter how
+filthy, and a very small amount will suffice. Thus any leaks from
+water-pipes or drains, cisterns, small cans of water or any such places
+may become dangerous breeding-places. If conditions are unfavorable
+there will often be developed small individuals which can easily make
+their way through ordinary mosquito-netting.</p>
+
+<p>Dr. Manson has pointed out an interesting possible result of the crusade
+that is now being waged against the yellow fever mosquitoes. The<span class='pagenum'><a name="Page_140" id="Page_140">[Pg 140]</a></span>
+immunity of the people native to the endemic regions is supposed to be
+due to their having had mild attacks of the fever during childhood, for
+the children in these regions are subject to certain fevers which are
+probably very mild forms of yellow fever.</p>
+
+<p>Now if we kill practically all of the <i>Stegomyia</i> so that these children
+do not have this fever there will be developed, in due time, a
+population most of whom are non-immune.</p>
+
+<p>This freedom from the disease for some time will allow us to grow
+careless in regard to fighting the mosquitoes. They will be allowed to
+increase and by some chance the yellow fever will again be introduced
+and there will then be very grave danger of most extensive and
+destructive epidemics.</p>
+
+
+<p class="center">DANGER OF THE DISEASE IN THE PACIFIC ISLANDS</p>
+
+<p>I have already referred once or twice to the conditions in many of the
+Pacific tropical islands. In some of these various species of
+<i>Stegomyia</i> are abundant, and in some <i>Stegomyia calopus</i> is the most
+abundant and troublesome form. All the natives of these islands are
+non-immune because there has never been any yellow fever there. Unless
+extraordinary care is taken the disease will be<span class='pagenum'><a name="Page_141" id="Page_141">[Pg 141]</a></span> introduced there sooner
+or later and the results are sure to be most appalling. The climatic and
+sanitary conditions and the habits of the people are ideal for the
+development and spread of the disease, and what I have seen of the
+conditions on some of these islands convinces me that it would be almost
+impossible to control the disease before it had a chance to kill a large
+percentage of the population.</p>
+
+<p>With the opening of the Panama Canal these things become more possible.
+Heretofore, the shipping to these regions has not been from ports where
+yellow fever was endemic or even likely to be epidemic. But unless the
+yellow fever is kept out of the canal zone, the danger will be many fold
+what it is now.</p>
+
+<p>The white man has already carried enough misery to these island peoples
+in the way of loathsome diseases, and it is to be hoped that this,
+another great curse, will not be carried to them with our civilization,
+the beneficial results of which have been so often very justly
+questioned.</p>
+
+<p>What I have said in regard to these islands applies with equal force and
+in some instances with even greater force to parts of Asia, the Eastern
+Archipelago and other places.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_142" id="Page_142">[Pg 142]</a></span></p>
+<h2><a name="CHAPTER_IX" id="CHAPTER_IX"></a>CHAPTER IX</h2>
+
+<h3>FLEAS AND PLAGUE</h3>
+
+<div class="figdrop">
+<img src="images/dropp.jpg" width="75" height="77" alt="dropp" title="" />
+</div>
+<p class="noin"><span class="caps">lague</span> has always been one of the most dreaded diseases, and when we
+read of its ravages in the old world and the utter helplessness of the
+people before it we do not wonder that the very word filled them with
+horror. One of the greatest scourges ever known began in Egypt about
+<span class="smcap">A.D.</span> 542, and spread along the shores of the Mediterranean to Europe and
+Asia. It lasted for sixty years, appearing again and again in the same
+place and decimating whole communities.</p>
+
+<p>Another great pandemic, beginning in 1364, spread over the whole of the
+then known world and appeared in its most virulent form. On account of
+diffuse subcutaneous hemorrhages it came to be known as the "black
+death" and of course spread terror in all the communities where it
+appeared. Whole villages and districts were depopulated. The death-rate
+was very high, one authority placing the total mortality at twenty-five
+million.</p>
+
+<p><span class='pagenum'><a name="Page_143" id="Page_143">[Pg 143]</a></span></p><p>During this time new centers of infection were established, and since
+then it has been carried by the commerce of the nations to all parts of
+the world. It is not restricted, as many other epidemic diseases, to the
+tropics or semi-tropics, although as a matter of fact we find it is more
+prevalent in these regions on account of the sanitary conditions.</p>
+
+
+<p class="center">HOW PLAGUE WAS CONTROLLED IN SAN FRANCISCO</p>
+
+<p>Attention is called to these things in order that we may compare past
+conditions with present. During the last few years San Francisco has
+been fighting an outbreak of plague that in other days would have been
+nothing less than a national calamity. But with modern methods of
+handling it, based on knowing what it is, what causes it and how it is
+spread, the authorities there have been able not only to hold the
+disease in check, but practically to stamp it out with the loss of
+comparatively few lives.</p>
+
+<p>Dr. Blue of the Public Health and Marine Hospital Service and his
+co-workers directed their whole energy toward controlling the rats. A
+small army of men were employed, catching rats in every quarter of the
+city. Dr. Rucker reports that fully a million rats were slain in this
+campaign.<span class='pagenum'><a name="Page_144" id="Page_144">[Pg 144]</a></span> Their breeding-places were destroyed by making cellars,
+woodsheds, warehouses, etc., rat-proof and removing all old rubbish.
+Garbage cans were installed in all parts of the city, as it was required
+that all garbage be stored where rats could not feed upon it, and
+altogether every effort was made to make it as uncomfortable as possible
+for the rats.</p>
+
+<p>The marked success attending this work abundantly confirms the soundness
+of the theory upon which it was based, and serves as another example of
+the way in which science is teaching us how to prevent or control many
+of our most serious diseases.</p>
+
+
+<p class="center">THE INDIAN PLAGUE COMMISSION</p>
+
+<p>In 1896, what proved to be a very serious outbreak of plague, occurred
+in Bombay and spread to other parts of India. In 1898, a commission was
+appointed to inquire into the origin of the different outbreaks, the
+manner in which the disease is communicated, etc. This was known as the
+Indian Plague Commission, and its exhaustive report, together with the
+minutes of the evidence presented to the committee, represents a
+stupendous amount of work on this subject and is the basis for much of
+the later investigation that has been undertaken.</p>
+
+<p><span class='pagenum'><a name="Page_145" id="Page_145">[Pg 145]</a></span></p><p>After the consideration of the evidence from various sources the
+commission decided that the principal mode of infection both for man and
+rats was through some sort of an abrasion in the skin, although it
+recognized also the possibility of infection through the nose and
+throat, and possibly, very rarely, through the intestinal tract or other
+places.</p>
+
+<p>Considerable time was spent in considering Dr. Simond's claim, made in
+1898, that fleas which have been parasitic on plague-infected rats
+migrate on the death of their hosts and convey the infection to healthy
+men and rats. Dr. Simond sought to establish the following:</p>
+
+<div class="blockquot"><p>"Firstly, that plague rats are eminently infective when infected
+with fleas and that they cease to be infective when they have been
+deserted by their parasites: Secondly, that living plague bacilli
+are found in association with fleas which are taken from
+plague-infected rats: Thirdly, that plague can pass from infected
+rats to other animals which have not come directly in contact with
+them or with their infected excretions: Fourthly, that fleas which
+infest rats will transfer themselves as parasites to men." </p></div>
+
+<p>After reviewing the experiments which had been made to establish these
+claims the commission believed that sufficient precaution had not been<span class='pagenum'><a name="Page_146" id="Page_146">[Pg 146]</a></span>
+taken to prevent infection from other sources and that not enough
+definite evidence was produced. Against this claim much negative
+evidence was considered and the final conclusion was "that suctorial
+insects do not come under consideration in connection with the spread of
+plague."</p>
+
+<p>In 1905 another body of men known as the Advisory Committee was
+appointed to arrange for further studies in India and other places,
+particularly in relation to the mode of dissemination of the disease.
+They at once appointed a new working commission who immediately began
+their studies and experiments. The preliminary reports of their work,
+which are still known as the Reports of the Indian Plague Commission, as
+well as the reports of contributing investigations that are being made
+from time to time, have served to establish entirely Dr. Simond's claims
+and have completely revolutionized the methods of fighting plague.</p>
+
+<p>There are several different types of plague, seeming to depend largely
+on the manner of infection. The most common type is that known as the
+bubonic plague which is characterized by buboes or swellings in various
+parts of the body. This form of infection is usually received through
+the skin in some manner or other. Only rarely does direct man-to-man
+infection occur though there is always<span class='pagenum'><a name="Page_147" id="Page_147">[Pg 147]</a></span> the possibility of it. The
+investigations have shown that the flea is the most common agent in
+transferring the disease from rat to rat or from rat to man. This may be
+accomplished by the flea transferring the bacilli directly from one host
+to another on its proboscis, or they may be carried in the alimentary
+canal of the flea and gain an entrance into the skin through an abrasion
+of some kind when the flea is crushed as it is biting, or when some of
+the bacilli are left on the skin in the excreta of the insect.</p>
+
+
+<p class="center">RESULTS OF VERJBITSKI'S EXPERIMENTS</p>
+
+<p>A very important series of experiments bearing directly on this subject
+was made in 1902 and 1903 by Dr. D.T. Verjbitski. The paper giving the
+results of this work was not published in any scientific journal until
+1908 when the Advisory Committee published it in one of their reports.
+The experiments were so well planned and executed and the results so
+definite that I think it is worth while to give in full his summary of
+results. The bugs referred to are bedbugs.</p>
+
+<div class="blockquot"><p>"(1) All fleas and bugs which have sucked the blood of animals
+dying from plague contain plague microbes.</p>
+
+<p>"(2) Fleas and bugs which have sucked the blood of animals which
+are suffering from plague only contain<span class='pagenum'><a name="Page_148" id="Page_148">[Pg 148]</a></span> plague microbes when the
+bites have been inflicted from 12 to 26 hours before the death of
+the animals, that is, during that period of their illness when
+their blood contains plague bacilli.</p>
+
+<p>"(3) The vitality and virulence of the plague microbes are
+preserved in these insects.</p>
+
+<p>"(4) Plague bacilli may be found in fleas from four to six days
+after they have sucked the blood of an animal dying with plague. In
+bugs, not previously starved or starved only for a short time (one
+to seven days), the plague microbes disappear on the third day; in
+those that have been starved for four to four and one-half months,
+after eight or nine days.</p>
+
+<p>"(5) The numbers of plague microbes in the infected fleas and bugs
+increase during the first few days.</p>
+
+<p>"(6) The f&aelig;ces of infected fleas and bugs contain virulent plague
+microbes as long as they persist in the alimentary canal of these
+insects.</p>
+
+<p>"(7) Animals could not be infected by the bites of fleas and bugs
+which had been infected by animals whose own infection had been
+occasioned by a culture of small virulence, notwithstanding the
+fact that the insects may be found to contain abundant plague
+microbes.</p>
+
+<p>"(8) Fleas and bugs that have fed upon animals which have been
+infected by cultures of high virulence convey infection by means of
+bites, and the more certainly so the more virulent the culture with
+which the first animal was inoculated.</p>
+
+<p><span class='pagenum'><a name="Page_149" id="Page_149">[Pg 149]</a></span>"(9) The local inflammatory reaction in animals which have died
+from plague occasioned by the bites of infected insects is either
+very slight or absent. In the latter case it is only by the
+situation of the primary bubo that one can approximately identify
+the area through which the plague infection entered the organism.</p>
+
+<p>"(10) Infected fleas communicate the disease to healthy animals for
+three days after infection. Infected bugs have the power of doing
+so for five days.</p>
+
+<p>"(11) It was not found possible for more than two animals to be
+infected by the bites of the same bugs.</p>
+
+<p>"(12) The crushing of infected bugs in situ during the process of
+biting, occasioned in the majority of cases the infection of the
+healthy animal with plague.</p>
+
+<p>"(13) The injury to the skin occasioned by the bite of bugs or
+fleas offers a channel through which the plague microbes can easily
+enter the body and occasion death from plague.</p>
+
+<p>"(14) Crushed infected bugs and fleas and their f&aelig;ces, like other
+plague material, can infect through the small punctures of the skin
+caused by the bites of bugs and fleas, but only for a short time
+after the infliction of these bites.</p>
+
+<p>"(15) In the case of linen and other fabrics soiled by crushing
+infected fleas and bugs on them, or by the f&aelig;ces of these insects
+the plague microbes can under favorable conditions remain alive and
+virulent during more than five months.</p>
+
+<p><span class='pagenum'><a name="Page_150" id="Page_150">[Pg 150]</a></span>"(16) Chemical disinfectants do not in the ordinary course of
+application kill plague microbes in infected fleas and bugs.</p>
+
+<p>"(17) The rat flea <i>Typhlopsylla musculi</i> does not bite human
+beings.</p>
+
+<p>"(18) Human fleas do bite rats.</p>
+
+<p>"(19) Fleas found on dogs and cats bite both human beings and rats.</p>
+
+<p>"(20) Human fleas and fleas found on cats and dogs can live on rats
+as casual parasites, and therefore can under certain conditions
+play a part in the transmission of plague from rats to human
+beings, and vice versa." </p></div>
+
+
+<p class="center">RESULTS OF VARIOUS INVESTIGATIONS</p>
+
+<p>Various other plague commissions from other countries as well as many
+individuals have investigated the same subject, and the results all
+point conclusively to the fact that the rats and the fleas are at least
+the most important factors in the spread of the disease. The evidence
+from many sources and from many experiments may be briefly summed up as
+follows: The disease is caused by the presence in the system of minute
+bacteria, <i>Bacillus pestis</i>. It is probable that plague is primarily a
+disease of rats and only secondarily and accidentally, as it were, a
+disease of man.</p>
+
+<p>Rats are subject to the plague and are often<span class='pagenum'><a name="Page_151" id="Page_151">[Pg 151]</a></span> killed by it in great
+numbers. An outbreak of plague among men is often preceded by a very
+noticeable outbreak among rats.</p>
+
+<p>Rats dying of the plague have their blood filled with the plague
+bacillus. Fleas or other suctorial insects feeding on such rats take
+myriads of these bacilli into their stomach and get many on their
+proboscis.</p>
+
+<p>The fleas usually leave a rat as soon as it dies and of course seek some
+other source of food. When such infected fleas are permitted to bite
+other rats or guinea-pigs these animals often develop the disease.
+Several of the species of fleas that infest rats will bite man also, and
+in the cases of many plague patients it can be definitely shown that
+they had recently been bitten by fleas.</p>
+
+
+<p class="center">STRUCTURE AND HABITS OF FLEAS</p>
+
+<p>A study of the structure and habits of fleas shows that in many respects
+they are particularly adapted for spreading such a disease as bubonic
+plague. The piercing proboscis consists of three long needle-like
+organs, the epipharynx and mandibles, and a lower lip or labium. The
+mandibles have the sides serrate like a two-edged saw. The labium is
+divided close to its base so that it really consists of two slender
+four-segmented organs which lie close<span class='pagenum'><a name="Page_152" id="Page_152">[Pg 152]</a></span> together and form a groove in
+which the piercing organs lie. When the flea is feeding, the epipharynx
+and mandibles are thrust into the skin of the victim, the labium serving
+as a guide. As the sharp cutting organs are thrust deeper and deeper the
+labium doubles back like a bow and does not enter the skin. Saliva is
+then poured into the wound through minute grooves in the mandibles, and
+the blood is sucked up into the mouth by the sucking organ which lies in
+the head at the base of the mouth-parts. Just above this piercing
+proboscis is a pair of flat, obtuse, somewhat triangular pieces, the
+maxillary blades or maxill&aelig;. When the proboscis is fully inserted into
+the skin the tips of these maxill&aelig; may also be embedded in the tissue
+and perhaps help to make the wound larger. Attached to these maxill&aelig; is
+a pair of rather stout, four-jointed appendages, the palpi. They
+probably act as feelers.</p>
+
+<p>If the flea chances to be feeding on a plague-infected rat or person
+many of the plague bacilli will get on the mouth-parts and myriads of
+them are of course sucked up into the stomach with the blood. Those on
+the proboscis may be transferred directly to the next victim that it is
+thrust into, and those in the stomach may be carried for some time and
+finally liberated when the flea is feeding again or when it is crushed
+by the annoyed host. The latter is probably the most common method of
+infection, for the bacilli that are liberated when the flea is crushed
+may readily be rubbed into the wound made by the flea bite or into
+abrasions of the skin due to the scratching. Kill the flea, but don't
+"rub it in."</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_105" id="Fig_105"></a>
+<img src="images/fig105.jpg" width="400" height="382" alt="Fig. 105" title="" />
+<span class="caption"><span class="smcap">Fig. 105</span>&mdash;Rat-flea (<i>L&aelig;mopsylla cheopis</i>); male.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_106" id="Fig_106"></a>
+<img src="images/fig106.jpg" width="400" height="296" alt="Fig. 106" title="" />
+<span class="caption"><span class="smcap">Fig. 106</span>&mdash;Rat-flea (<i>L. cheopis</i>); female.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_107" id="Fig_107"></a>
+<img src="images/fig107.jpg" width="400" height="396" alt="Fig. 107" title="" />
+<span class="caption"><span class="smcap">Fig. 107</span>&mdash;Head of rat-flea showing mouth-parts.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_108" id="Fig_108"></a>
+<img src="images/fig108.jpg" width="400" height="336" alt="Fig. 108" title="" />
+<span class="caption"><span class="smcap">Fig. 108</span>&mdash;Human-flea (<i>Pulex irritans</i>); male.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_153" id="Page_153">[Pg 153]</a></span></p><p>During the recent outbreak in San Francisco many thousand fleas that
+were infesting man, rats, mice, cats, and dogs, squirrels and other
+animals have been studied and it has been found that while each flea
+species has its particular host upon which it is principally found, few
+if any of them will hesitate to leave this host when it is dead and
+attack man or any other animal that may be convenient.</p>
+
+
+<p class="center">COMMON SPECIES OF FLEAS</p>
+
+<p>Throughout India and in all the warm climates where plague frequently
+occurs the most common flea found on rats has come to be known as the
+plague flea (<i>L&aelig;mopsylla cheopus</i>) (<a href="#Fig_105">Figs. 105</a>, <a href="#Fig_106">106</a>), and is doubtless
+the principal species that is concerned in carrying the disease in those
+climates. It now occurs quite commonly on the rats in the San Francisco
+Bay region and is occasionally found there on man also. In the United
+States, Great Britain and other temperate regions another<span class='pagenum'><a name="Page_154" id="Page_154">[Pg 154]</a></span> larger
+species, <i>Ceratophyllus fasciatus</i> is by far the most common flea found
+on rats, and is commonly known as the rat flea. It occurs on both the
+brown and the black rats <i>Mus norvegicus</i> and <i>M. rattus</i>, on the house
+mouse and frequently on man. It has also been taken in California on
+pocket gophers and on a skunk.</p>
+
+<p>The common human flea (<i>Pulex irritans</i>) (<a href="#Fig_108">Figs. 108</a>, <a href="#Fig_109">109</a>), is found in
+all parts of the inhabited world. Although we regard it primarily as a
+pest of human beings it often occurs very abundantly on cats, dogs, mice
+and rats as well as on some wild mammals such as badgers, foxes and
+others and has occasionally been found on birds.</p>
+
+<p>Most entomologists regard the fleas commonly found on cats and dogs as
+belonging to one species <i>Ctenocephalus canis</i>. Others believe them to
+be distinct species and call the cat flea <i>Ctenocephalus felis</i>. So far
+as our personal comfort and safety is concerned it makes but little
+difference to us whether the flea that bites us is called <i>canis</i> or
+<i>felis</i> for they both look very much alike, and act alike and the bite
+of one hurts just as much as the bite of the other. Although cats and
+dogs are their normal hosts they are very often troublesome household
+pests, sometimes making a house almost uninhabitable. They are
+frequently found on rats,<span class='pagenum'><a name="Page_155" id="Page_155">[Pg 155]</a></span> and therefore may carry the plague bacillus
+from rat to rat or from rat to man.</p>
+
+
+<p class="center">GROUND-SQUIRRELS AND PLAGUE</p>
+
+<p>As early as 1903 Dr. Blue, in charge of the plague suppressive measures
+in San Francisco, became impressed with the possibility of the common
+California ground-squirrels (<i>Otospermophilus beecheyi</i>), acting as an
+agent in the transmission of plague. It was rumored at that time that
+some epidemic disease was killing the squirrels in some of the counties
+surrounding San Francisco Bay, notably in Contra Costa County. None of
+the squirrels were examined at that time, but since then many thousand
+have been carefully studied and it has been definitely shown that many
+of them are plague-infected. Just how the plague got started among them
+will probably never be really known. There is little doubt, however, but
+that it was transferred in some way from the rats to the squirrels. The
+trains and the bay and river steamers running out from San Francisco
+would afford abundant opportunity for the rats to go from the city to
+the warehouses all along the shore. Once there they would use the same
+runways as the squirrels about the warehouses and in the near-by fields.
+In harvest time the rats migrate to the fields and make constant<span class='pagenum'><a name="Page_156" id="Page_156">[Pg 156]</a></span> use of
+the squirrel holes. The farmers in some sections report that they
+frequently catch more rats than squirrels in traps set in squirrel holes
+at that season of the year.</p>
+
+<p>This close association of the rats and the squirrels affords a good
+opportunity for the fleas infesting them to pass from one host to the
+other.</p>
+
+<p>So far only two species of fleas have been recorded from the
+ground-squirrels. One, <i>Ceratophyllus acutus</i>, is very common, sometimes
+literally swarming over the squirrels, particularly if a squirrel is
+sick or weak from any cause. The other species, <i>Hoplopsyllus anomalus</i>,
+is less abundant but still quite common. Both of these species infest
+rats also, so the chain of evidence is practically complete. We have
+only to assume that at sometime one or more of the plague-infected rats
+found their way into the region where the squirrels were, and the fleas
+passing from the rats to the squirrels would carry the plague with them.</p>
+
+<p>The fact that the plague already has such a start among the squirrels
+opens a new and very serious phase of the problem of suppressing the
+disease. All who have hunted the ground-squirrels will testify to the
+readiness with which the fleas from them will bite those who are
+handling them. As it is the sick or weak squirrels that are most often
+taken there is always a chance that plague may be transferred from them
+to human beings. The records of the plague cases in California show at
+least three cases in which there seems to be very little doubt that the
+disease resulted from handling plague-infected squirrels.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_109" id="Fig_109"></a>
+<img src="images/fig109.jpg" width="400" height="351" alt="Fig. 109" title="" />
+<span class="caption"><span class="smcap">Fig. 109</span>&mdash;Human-flea (<i>P. irritans</i>); female.</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_110" id="Fig_110"></a>
+<img src="images/fig110.jpg" width="400" height="199" alt="Fig. 110" title="" />
+<span class="caption"><span class="smcap">Fig. 110</span>&mdash;Mouse-flea (<i>Ctenopsyllus musculi</i>); female.</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_157" id="Page_157">[Pg 157]</a></span></p><p>A still more serious thing is the possibility of the disease remaining
+in a more or less virulent form among the squirrels for some time,
+possibly for years, and then breaking out again in some locality where
+the rats or men may become infected. As long as there is a trace of the
+disease among the squirrels there is always the chance of it spreading,
+so that new areas may become infested. Those in charge of the
+plague-suppressive measures are fully aware of these dangers and are
+making a careful study of the situation and will doubtless be able to
+cope with it successfully. It may be that the squirrels will have to be
+exterminated in the infected regions. This would be a long and difficult
+task, but the success attending the fight against the rats in a great
+city shows what can be done when the determination to do it is there.</p>
+
+
+<p class="center">REMEDIES FOR FLEAS</p>
+
+<p>We have seen how a great city set to work to rid itself of the
+plague-sick rats. As a matter of fact<span class='pagenum'><a name="Page_158" id="Page_158">[Pg 158]</a></span> it was not the rats that they
+were after primarily. If the rats had not harbored fleas the city would
+have been glad to let the disease take its course and destroy as many
+rats as possible. But it was found that the only way to get rid of the
+fleas that might possibly be infected with the plague was to kill their
+rat hosts.</p>
+
+<p>General cleaning-up measures will of course very materially lessen the
+number of fleas about the private dwellings, but there often remains a
+number of fleas in the house that are a source of great annoyance even
+if the danger is eliminated.</p>
+
+<p>Particularly is this apt to be so in places where cats or dogs are
+members of the household. These animals almost always harbor at least a
+few fleas, and where there are a few there is always a possibility, even
+a great probability, that there will be many more unless an effort is
+made to get rid of them.</p>
+
+<p>In some sections of the country it is the cat and dog flea that is the
+most troublesome to man. The minute white eggs of the fleas are usually
+laid about the sleeping-places of these animals and the slender active
+larv&aelig; that hatch from them feed upon any kind of organic matter that
+they can find in the dust or in the cracks and crevices. About eight or
+ten days after hatching the larv&aelig; spin delicate<span class='pagenum'><a name="Page_159" id="Page_159">[Pg 159]</a></span> brownish cocoons in
+which they pass the pupal stage, issuing a few days later as the adult
+fleas.</p>
+
+<p>It will at once appear, then, that it is important to provide the cats
+and dogs with sleeping-places that can be kept clean. If they have a mat
+or blanket to sleep on this can be taken up and shaken frequently and
+the dust swept up and burned. In this way many of the eggs or larv&aelig; may
+be destroyed. Very often the dust under a carpet that has not been taken
+up and dusted for some time will be found to be harboring a multitude of
+fleas or their larv&aelig;. In such cases a thorough cleaning of the carpet
+and the floors will bring relief. Houses that are unused for some time
+during the summer months are often found to be overrun with fleas in the
+fall, for the fleas have had an unmolested opportunity to breed and
+multiply. Such rooms of course require a thorough cleaning or it is
+sometimes possible to kill the fleas by a liberal use of pyrethrum
+powder or benzine or to fumigate. In this connection, Dr. Skinner's note
+in the <i>Journal of Economic Entomology</i> is worth repeating.</p>
+
+<div class="blockquot"><p>"In the latter part of last May (1908) I moved into a house that
+had not been previously occupied. No carpet was used and being
+summer only a few rugs were placed on the floors. A part of the
+household consisted<span class='pagenum'><a name="Page_160" id="Page_160">[Pg 160]</a></span> of a collie dog and three Persian cats. Very
+soon the fleas appeared, the dog and cat flea, <i>Ctenocephalus
+canis</i>. I did not count them and I can't say whether they numbered
+a million or only a hundred thousand. On arising in the morning and
+stepping on the floor one would find from three to a dozen on the
+ankles. The usual remedies for fleas are either drastic or somewhat
+unsatisfactory. The drastic one is to send the animals to the
+institutions, where they are asphyxiated, or take the other advice,
+'Don't keep animals.'</p>
+
+<p>"I tried mopping the floors with rather a strong solution of
+creolin but it did little good. Previous experience with pyrethrum
+was not very satisfactory. Knowing the volatility of naphthalene in
+warm weather and the irritating character of its vapor led me to
+try it. I took one room at a time, scattered on the floor five
+pounds of flake naphthalene and closed it for twenty-four hours. On
+entering such a room the naphthalene vapor will instantly bring
+tears to the eyes and cause coughing and irritation of the air
+passages. I mention this to show how it acts on the fleas. It
+proved to be a perfect and effectual remedy and very inexpensive,
+as the naphthalene could be swept up and transferred to other
+rooms. So far as I am concerned the flea question is solved and if
+I have further trouble I know the remedy. I intend to keep the dog
+and the cats." </p></div>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_161" id="Page_161">[Pg 161]</a></span></p>
+<h2><a name="CHAPTER_X" id="CHAPTER_X"></a>CHAPTER X</h2>
+
+<h3>OTHER DISEASES, MOSTLY TROPICAL, KNOWN OR THOUGHT TO BE TRANSMITTED BY
+INSECTS</h3>
+
+
+<p class="center">SLEEPING SICKNESS</p>
+
+<div class="figdrop">
+<img src="images/dropo.jpg" width="75" height="76" alt="dropo" title="" />
+</div>
+<p class="noin"><span class="caps">ne</span> of the worst scourges of Africa and one that is to-day attracting
+world-wide attention is the disease known as trypanosomiasis, the
+terminal phase of which is sleeping sickness, one of the most ghastly
+diseases that we know.</p>
+
+<p>Among the Protozoa referred to in one of the earlier chapters mention
+was made of certain trypanosomes which inhabit the blood of man and
+certain animals. Very little was known concerning these parasites
+previous to the beginning of the present century, but since that time
+several have been found to be of great economic importance. The group is
+being studied extensively and every day our knowledge of them is
+increasing so that we now know quite definitely the life-history of
+several.</p>
+
+<p><span class='pagenum'><a name="Page_162" id="Page_162">[Pg 162]</a></span></p><p><i>Trypanosoma lewisi</i>, a parasite of rats, is perhaps the best known as
+it is always common where-ever rats are found. Sometimes as many as 30%
+or 40% of the rats of certain districts are infected. It is thought that
+these are transmitted from rat to rat by the common rat-louse which
+serves as an intermediate host. Fleas may also act as disseminating
+agents.</p>
+
+<p>A few other kinds cause serious disease of animals, but we are more
+interested just now in the particular one that is causing so much
+trouble in Africa. This parasite was discovered in 1902 and was named
+<i>Trypanosoma gambiensi</i> (<a href="#Fig_111">Fig. 111</a>). Since then it has been found to be
+widely distributed. Although the natives have doubtless long been
+subject to the disease caused by this parasite, the recent influx of
+whites to these regions and the consequent movements of the natives have
+caused a great spread of the disease so that whole regions are now made
+desolate, the inhabitants dying or fleeing to escape the uncanny death.</p>
+
+<p>The disease may run its course in a few months or it may take years. The
+symptoms are various, but infection is usually soon followed by fevers,
+sometimes mild, sometimes severe, which recur at irregular intervals.
+Certain glands or other parts of the body may become swollen. More or
+less<span class='pagenum'><a name="Page_163" id="Page_163">[Pg 163]</a></span> extensive skin eruptions occur on all parts of the body and the
+patient gradually becomes anemic and physically and intellectually
+feeble. The nervous system seems to be affected by the parasite, either
+directly or by the action of the toxins it produces. The patient becomes
+more debilitated and morose with an increasing tendency to sleep, hence
+the name sleeping sickness. As the stupor deepens the patient looses all
+desire or power of exertion and as little food is taken he rapidly
+wastes away and finally succumbs for after this final stage is reached
+there is no relief.</p>
+
+<p>It is definitely known that a species of tsetse-fly, <i>Glossina palpalis</i>
+(<a href="#Fig_112">Fig. 112</a>), which somewhat resembles our stable-fly, is responsible for
+the dissemination of the disease, and some recent investigators have
+suggested that certain species of mosquitoes may also carry the parasite
+from one host to another. There still remains some doubt as to the exact
+manner in which the fly transmits the disease, but it seems altogether
+likely that it is an alternative host and does not serve as a simple
+mechanical carrier. In this respect it is like the mosquito which is one
+of the necessary hosts of the malaria parasites, and unlike the
+house-fly which carries the germs of various diseases in a<span class='pagenum'><a name="Page_164" id="Page_164">[Pg 164]</a></span> purely
+mechanical way without serving as a definite necessary host for the
+parasite.</p>
+
+<p>The tsetse-fly is found only in tropical Africa and is limited in its
+distribution there to certain very definite, narrow, brushy areas along
+the water's edge. If these places can be avoided there seems to be
+little danger. Those who are fighting the disease have found that if the
+brush in the vicinity of watering-places and ferry-landings is cleared
+away such places become comparatively safe. These flies do not lay eggs
+but produce full-grown larv&aelig; which soon pupate in the ground.</p>
+
+
+<p class="center">ELEPHANTIASIS</p>
+
+<p>In many tropical regions human blood as well as that of other animals is
+the normal habitat of certain worm-like parasites (Nematodes). They are
+not entirely confined to the tropics but may extend far up into the
+subtropical regions. Five or six different species of these parasites
+are known, only one of which, however, has been shown to be of any
+pathological importance, as far as human beings are concerned.</p>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_111" id="Fig_111"></a>
+<img src="images/fig111.jpg" width="400" height="345" alt="Fig. 111" title="" />
+<span class="caption"><span class="smcap">Fig. 111</span>&mdash;<i>Trypanosoma gambiense</i>; various forms from
+blood and cerebrospinal fluid. (After Manson.)</span>
+<br /><br /></div>
+
+<div class="figcenter" style="width: 400px;"><a name="Fig_112" id="Fig_112"></a>
+<img src="images/fig112.jpg" width="400" height="318" alt="Fig. 112" title="" />
+<span class="caption"><span class="smcap">Fig. 112</span>&mdash;Tsetse-fly. (After Manson.)</span>
+</div>
+
+<p><span class='pagenum'><a name="Page_165" id="Page_165">[Pg 165]</a></span></p><p>This species, <i>Filaria bancrofti</i>, is not only very widely distributed,
+but in regions such as some of the South Sea Islands a very large per
+cent of the natives have the filari&aelig; present in their blood. When these
+parasites are withdrawn from the circulation and placed on a slide for
+study they are seen to be minute transparent, colorless, snake-like
+organisms inclosed in a very delicate sack or sheath. They are but a
+little more than one-hundredth of an inch long and about as big around
+as a red blood-corpuscle. These are the larval forms of the parasite and
+have been called by Le Dantec the micro-filaria.</p>
+
+<p>If blood of the patient drawn from the skin, is examined during the day
+few if any of these parasites are found, but if it is examined between
+five or six o'clock in the evening and eight or nine o'clock the next
+morning they may be found in numbers. During the daytime they have
+retired from the peripheral circulation to the larger arteries and to
+the lungs, where they may be found in great numbers.</p>
+
+<p>This night-swarming to the peripheral circulation has been found to be a
+remarkable adaptation in the life-history of the parasite, for it has
+been demonstrated that in order to go on with its development these
+larval forms must be taken into the alimentary canal of the mosquito.
+Most of the mosquitoes in which the development takes place are
+night-feeders, so that the parasites are sucked up with the blood of the
+victim. Once inside the<span class='pagenum'><a name="Page_166" id="Page_166">[Pg 166]</a></span> stomach they soon free themselves from the
+inclosing sheath and make their way through the walls of the stomach and
+enter the muscular tissue, particularly the thoracic muscles. Here they
+undergo a metamorphosis and increase enormously in size, some attaining
+one-sixteenth of an inch in length.</p>
+
+<p>After sixteen to twenty days they leave these muscles and make their way
+to other parts of the body. A few may be found in different parts of the
+abdomen, but most of them make their way forward into the head of the
+mosquito and coil themselves up close to the base of the proboscis,
+finally finding their way down into the proboscis inside the labium.
+Here they lie until an opportunity offers for them to escape to the warm
+blood of a vertebrate. They probably pass through the thin membrane
+connecting the labella with the proboscis and there find their way into
+the wound made by the puncture when the insect bites. Whether these
+parasites can gain an entrance into the circulatory system in any other
+way is not known. It has been suggested that the mosquitoes dying and
+disintegrating on the surface of water may liberate the filari&aelig; which
+may later find their way into the system of the vertebrate host when the
+water is used for drinking, but most of the investigations<span class='pagenum'><a name="Page_167" id="Page_167">[Pg 167]</a></span> made so far
+seem to indicate that they make their way directly from the proboscis
+into the new host.</p>
+
+<p>Soon after entering the circulatory system of the human host the
+parasites make their way into the lymphatics where they attain sexual
+maturity, and in due time new generations of the larval filari&aelig; or
+microfilari&aelig; are poured into the lymph, and finally into the definite
+blood-vessels, ready to be sucked up by the next mosquito that feeds on
+the patient.</p>
+
+<p>In most cases of infection the presence of these filari&aelig; in the blood
+seems to cause no inconvenience to the host. They are probably never
+injurious in the larval stage, that is, in the stage in which they are
+found in the peripheral circulation.</p>
+
+<p>In many cases, however, the presence of the sexual forms in the
+lymphatics may cause serious complications. The most common of these is
+that hideous and loathsome disease known as elephantiasis in which
+certain parts of the patient becomes greatly swollen and distorted. An
+arm or a leg may become swollen to several times its natural size, or
+other parts of the body may be seriously affected.</p>
+
+<p>In some of the South Sea Islands 30% to 40% of the natives are afflicted
+in this way, some only slightly others seriously. There is little or no
+pain,<span class='pagenum'><a name="Page_168" id="Page_168">[Pg 168]</a></span> but in severe cases the distorted parts often render the patient
+entirely helpless.</p>
+
+<p>The exact way in which the parasites cause such swelling is not very
+definitely known. Manson, who has done more work on these diseases than
+any one else, believes that the trouble arises from the clogging of the
+lymphatic glands or trunks, thus cutting them off from the general
+circulation, in which case the affected parts may become distorted. This
+clogging of the passages is believed to be due to the presence of great
+numbers of immature eggs which have been liberated by parasites injured
+in some way before their eggs were entirely developed.</p>
+
+<p>This interference with the lymphatic circulation brings about the
+anomalous condition of a patient with a serious filarial disease with
+fewer of the filarial parasites in his blood than one who is not so
+seriously affected. This is supposed to be due to the fact that the
+disease-producing parasites have died and that the lymphatics have
+become so obstructed that any microfilari&aelig; they may contain cannot make
+their way into the general circulation. Such a patient then would not be
+as likely to infect a mosquito as would one less seriously affected.</p>
+
+<p>It has always been thought that little or nothing could be done in the
+way of successfully treating<span class='pagenum'><a name="Page_169" id="Page_169">[Pg 169]</a></span> this disease, but quite recently a French
+physician, who has been conducting a long series of experiments in the
+Society Islands, announced that he is able to cure many cases by certain
+surgical operations on the affected parts.</p>
+
+
+<p class="center">DENGUE OR "BREAKBONE FEVER"</p>
+
+<p>This is another disease of the tropics often occurring in widespread
+epidemics. It is probably most frequently met with in the West Indies,
+but may occur in any of the tropical countries or islands. Occasionally
+it spreads into subtropical or even temperate regions. Several extensive
+epidemics have occurred in the United States. Once introduced into a
+community it spreads very rapidly and nothing seems to confer immunity.</p>
+
+<p>The various names by which it has been called well describe its effect
+on the patient; breakbone fever, dandy-fever, stiff-necked or
+giraffe-fever, boquet (or "bucket") fever, <i>scarlatina rheumatica</i>,
+polka-fever, etc. While the suffering is intense as long as the disease
+lasts it seldom terminates fatally.</p>
+
+<p>It has always been classed as a very contagious disease and it has not
+yet been definitely shown that it is not. Recent observations, however,
+have shown that it is probably caused by a certain<span class='pagenum'><a name="Page_170" id="Page_170">[Pg 170]</a></span> Protozoan parasite
+that is found in the blood of dengue patients and several experiments
+have been conducted by Dr. Graham which seem to indicate that it is
+transmitted by mosquitoes. In these experiments, <i>Culex fatigans</i>, a
+common tropical or subtropical mosquito, was used. The same parasite
+that is found in the human blood may be found in the stomach and blood
+of the mosquitoes up to the fifth day after it has fed on a dengue
+patient.</p>
+
+<p>Sick and healthy individuals were allowed to remain in close contact in
+a room from which the mosquitoes had been excluded, and the disease was
+not spread. Mosquitoes that had bitten dengue patients were taken to a
+higher region where dengue had never occurred and allowed to bite two
+healthy persons. Both developed the disease and as they were protected
+from other mosquitoes until they had recovered, the disease did not
+spread to others of the community. These and other observations seem to
+make a complete chain of evidence, and most medical men to-day accept
+the theory as well proved and in their practice take every precaution to
+prevent the spread of the disease by keeping the infected patient from
+being bitten by the mosquitoes.</p>
+
+<p>The yellow fever mosquito is also suspected of carrying this same
+disease, and it is possible that<span class='pagenum'><a name="Page_171" id="Page_171">[Pg 171]</a></span> other species are also concerned. If
+it is true that the parasite can be carried by several different species
+of mosquitoes this would account very largely for its rapid spread
+wherever it is introduced into a community. Where it occurs outside the
+tropics it is only in the warm summer months when mosquitoes are always
+abundant.</p>
+
+
+<p class="center">MALTA OR MEDITERRANEAN FEVER</p>
+
+<p>This is also a tropical and subtropical disease that occasionally gets
+up into the temperate region, sometimes occurring in the United States.
+The fever begins with a severe headache, and other symptoms follow. It
+is usually of the remittent type and may continue for some months.</p>
+
+<p>It is caused by minute bacteria (<i>Micrococcus melitensis</i>) and is a very
+infectious but not usually contagious disease. The germ is readily
+conveyed by inoculation, and several investigators have sought to show
+that the mosquito often serves as the inoculating agent. The disease is
+especially prevalent during the mosquito season, and has twice been
+conveyed to monkeys by infected insects.</p>
+
+
+<p class="center">LEPROSY</p>
+
+<p>This loathsome disease has long been known to be caused by a particular
+bacillus (<i>Bacillus lepr&aelig;</i>),<span class='pagenum'><a name="Page_172" id="Page_172">[Pg 172]</a></span> but the way in which this organism gains
+an entrance into the system is still unknown. Many theories have been
+propounded, but none of them has been well established. Within recent
+years the possibility of insects carrying the germ and in one way or
+another transmitting it to healthy individuals has been suggested and
+much discussed. As the lepr&aelig; bacilli are present in the skin and ulcers
+of leprous patients, insects sucking the blood or feeding on the sores
+could not help taking some of them into their body or becoming
+contaminated. These bacilli have been found at various times in the
+stomach or intestine of mosquitoes, fleas and bedbugs. So it is believed
+by some that these and other insects, such as lice and flies, may
+sometimes transmit the disease. On a previous page we have referred to
+the possibility of the face-mites acting as disseminators of leprosy.</p>
+
+<p>Leprosy occurs most commonly among people where little attention is paid
+to bodily cleanliness. Such people are usually freely infested with
+various parasites that thrive well in the filth, so if the germs can be
+transmitted in this way the carriers are there in abundance.</p>
+
+<p>The fact that the sores usually occur on exposed parts of the body has
+been pointed to as evidence that inoculation is due to such insects as
+flies and<span class='pagenum'><a name="Page_173" id="Page_173">[Pg 173]</a></span> mosquitoes. It has been noted that leprosy is frequently very
+common in regions where elephantiasis occurs, suggesting the possibility
+of the same carrier, the mosquito, for both diseases. So while there is
+as yet very little evidence one way or the other, insects that are found
+around leprous patients are to be regarded with suspicion, for until we
+know more definitely just how the disease is communicated the insects
+must be looked on as possible sources of contamination.</p>
+
+
+<p class="center">KALA-AZAR OR DUM-DUM FEVER</p>
+
+<p>This is a very fatal infectious disease of many tropical and subtropical
+regions, spreading terror among the natives wherever it occurs. It is
+caused by the presence in the system of Protozoan parasites, the
+so-called Leishman-Donovan bodies, that have recently been studied by
+several observers.</p>
+
+<p>Dr. W.S. Patton of the Indian Medical Service has been making some
+extensive experiments with the common bedbug of India (<i>Cimex
+rotundatus</i>) which seem to demonstrate fully that this insect is
+responsible for the transmission of the parasite that causes the
+disease. He has found the parasite in all stages of development in the
+bedbug. This, taken with a number of other observations in regard to the
+tendency of the disease to cling to particular<span class='pagenum'><a name="Page_174" id="Page_174">[Pg 174]</a></span> houses, makes a strong
+case against the bedbug. Manson, however, believes that the parasite may
+be transmitted by other agents also, possibly by means of flies that
+visit the sores or in other ways.</p>
+
+
+<p class="center">ORIENTAL SORE</p>
+
+<p>This disease, once supposed to be confined to the Orient, is now found
+to be rather widely distributed throughout the tropics, where it is
+sometimes very prevalent. It is caused by the presence in the system of
+a parasite very similar to or identical with the one causing <i>kala-azar</i>
+and is regarded by some as a modified form of that disease. The patient
+is affected with one or more serious sores or ulcers which usually occur
+on exposed parts of the body.</p>
+
+<p>The parasite that causes the disease is supposed to be carried by
+insects either directly or indirectly.</p>
+
+<p>In the latter case the insect may act as an intermediate host.</p>
+
+<p>Dogs and camels are also attacked by this disease and may be sources of
+infection.</p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_175" id="Page_175">[Pg 175]</a></span></p>
+<h2><a name="BIBLIOGRAPHY" id="BIBLIOGRAPHY"></a>BIBLIOGRAPHY</h2>
+
+<div class="figdrop">
+<img src="images/dropa.jpg" width="75" height="76" alt="dropa" title="" />
+</div>
+<p class="noin"><span class="caps">complete</span> list of books and articles dealing more or less directly with
+the subjects discussed in this book would be too extended for use here.
+For the past ten or twelve years many of the medical and biological
+journals have contained articles in almost every issue, discussing these
+subjects in some of their phases. I have selected only a few of the more
+important of them, and these only the English ones, confining myself
+mostly to those that I have personally consulted, and giving brief
+annotations. Many of these will be found to include very full
+bibliographies of the particular subject treated.</p>
+
+<p>In order to avoid repetition, references are given under one head only
+although many might properly be included in other sections as well.</p>
+
+
+<p class="center">PARASITES AND PARASITISM</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Braun, Max.</span> Animal Parasites of Man. Translated by Pauline Falcke
+and edited by L.W. Sambon and F.V. Theobald. Third edition, 1906. A
+chapter on the general subject of parasitism and a description of
+parasites of all classes. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Leuckart, R.</span> The Parasites of Man and the Diseases Induced by Them.
+Eng. transl., London, 1886.</p>
+
+<p><span class='pagenum'><a name="Page_176" id="Page_176">[Pg 176]</a></span></p><p class="hang"><span class="smcap">Neuman, Theo.</span> Entoparasites and Hygiene. <i>Trans. Vassar Bros.
+Institute</i>, VII, 1895. A general discussion of parasitism;
+life-history of some common parasites that infest man.</p>
+
+<p class="hang"><span class="smcap">Neumann, L.G.</span> Treatise on the Parasites and Parasitic Diseases of
+the Domesticated Animals. Eng. transl. by Fleming, 1892.</p>
+
+<p class="hang"><span class="smcap">Ransom, B.H.</span> How Parasites Are Transmitted. <i>Year Book U.S. Dept.
+Agric.</i>, 1905, pp. 139&ndash;166 (pub. 1906). Discusses the ways in which
+parasites of all classes are transmitted.</p>
+
+<p class="hang"><span class="smcap">Sambon, L.</span> The Part Played by Metazoan Parasites in Tropical
+Pathology. <i>Jour. Trop. Med. &amp; Hyg.</i>, Vol. XI, Jan. 15, 1908. A
+comprehensive discussion of this subject.</p>
+
+<p class="hang"><span class="smcap">Shipley, A.E., and Fearnsides, E.G.</span> Effects of Metazoan Parasites
+on Their Hosts. <i>Jour. Econom. Biology</i>, Vol. I, 1906, pp. 41&ndash;62.
+Discusses injury due to mere presence of parasite in host; to the
+migration of the parasite; loss to host by feeding of parasites;
+injury by certain toxins.</p>
+
+<p class="hang"><span class="smcap">Stiles, C.W.</span> Diseases Caused by Animal Parasites. <i>Osler's Mod.
+Med.</i>, Vol. I, 1907, p. 525. General discussion; Trematodes;
+Cestodes; Roundworms; Acariasis; Parasitic Insects; Myiasis.</p>
+
+<p class="hang"><span class="smcap">Van Beneden, P.J.</span> Animal Parasites and Messmates. 1889. Contains
+much that is interesting.</p>
+
+<p class="hang"><span class="smcap">Ward, Henry B.</span> Influence of Parasitism on the Host. <i>Proc. Amer.
+Assn. for Advancement of Science</i>, Vol. 56, 1907. A comprehensive
+statement of this subject. List of literature. </p></div>
+
+
+<p class="center">PROTOZOA</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Calkins, G.N.</span> The Protozoa. <i>Osler's Mod. Med.</i>, Vol. I, 1907, p.
+353. General notes on the Protozoa; classification; reproduction;
+life-cycle of various forms. Regards Protozoa as subkingdom and the
+four great divisions as phyla.</p>
+
+<p class="hang"><span class="smcap">Calkins, G.N.</span> Protozo&ouml;logy. N.Y., 1909. Chapters on parasitism,
+pathogenic Protozoa, etc.</p>
+
+<p><span class='pagenum'><a name="Page_177" id="Page_177">[Pg 177]</a></span></p><p class="hang"><span class="smcap">Clarke, J.J.</span> Protozoa and Disease. London, 1903, Pt. I. Discusses
+the various protozoa that cause disease, and refers frequently to
+those that are transferred from host to host by insects.</p>
+
+<p class="hang"><span class="smcap">Clarke, J.J.</span> Protozoa and Disease. London, 1908. Part II,
+comprising sections on the causation of smallpox, syphilis and
+cancer. Notes on parasitic Protozoa, tropical diseases, ticks,
+piroplasmosis, etc.</p>
+
+<p class="hang"><span class="smcap">Daniels, C.W.</span> Persistence of the Tropical Diseases of Man Due to
+Protozoa. <i>Jour. Trop. Med. &amp; Hyg.</i>, 12, Aug. 2, 1909, pp. 232&ndash;234.
+Same in <i>Lancet</i>, II, 1909, p. 460. Good summary of present
+knowledge of the subject.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> Protozoa. In Albutt and Rolleston's <i>System of
+Medicine</i>, II, 1907, pp. 9&ndash;122. A comprehensive chapter on
+Protozoa. Many parasitic forms are figured and described.
+Bibliography.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> The Sporozoa. In Lankester's <i>Treatise on Zo&ouml;l.</i>, Pt.
+I, pp. 150&ndash;360, 1903. Best account of this group, list of Sporozoan
+hosts. Bibliography. </p></div>
+
+
+<p class="center">BACTERIA</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Flexner, Simon.</span> Relation of Bacteria and Sporozoa to Disease.
+<i>Science</i>, N.S., Vol. 27, No. 682, pp. 133&ndash;136. On these pages
+discusses relation of bacteria and Protozoa to human diseases.</p>
+
+<p class="hang"><span class="smcap">Jordan, Edwin O.</span> General Bacteriology. Philad., 1898. A good
+general treatment of the subject.</p>
+
+<p class="hang"><span class="smcap">Levy, Ernst, and Klemperer, Felix.</span> Elements of Clinical
+Bacteriology for Physicians and Students (transl. by A.A. Eschner),
+Philad., 1909. Morphology and biology of bacteria; infection;
+immunity; specific diseases of bacterial origin, etc.</p>
+
+<p class="hang"><span class="smcap">Muir, Robt., and Ritchie, Jas.</span> Manual of Bacteriology.<span class='pagenum'><a name="Page_178" id="Page_178">[Pg 178]</a></span> N.Y., 1903.
+Contains chapter on the relation of bacteria to diseases and
+discussion of several bacterial diseases.</p>
+
+<p class="hang"><span class="smcap">Sternberg, G.M.</span> A Manual of Bacteriology. N.Y., 1893. Part III is
+devoted to pathogenic bacteria. </p></div>
+
+
+<p class="center">INSECTS AND DISEASE</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Herms, W.B.</span> Medical Entomology, Its Scope and Methods. <i>Jour. of
+Eco. Ento.</i>, Vol. 2, No. 4, 1909, pp. 265&ndash;268.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Insects as Carriers and Spreaders of Disease. <i>Year
+Book U.S. Dept. Agric.</i>, 1901, pp. 177&ndash;192. Good review of the
+subject.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> How Insects Affect Health in Rural Districts. <i>U.S.
+Dept. Agric., Farmers' Bulletin, No. 155</i>, 1902. Discussion of city
+and county conditions; protection from typhoid, malaria and yellow
+fever.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Economic Loss to the People of U.S. Through Insects
+That Cause Disease. <i>Bull. 78, U.S. Dept. Agric. Bur. of Ent.</i>,
+1909. A comprehensive discussion and summary of the subject.
+Discusses mosquitoes, flies, the Panama Canal, epidemic diseases
+and the progress of nations.</p>
+
+<p class="hang"><span class="smcap">Kellogg, V.L.</span> Insects and Disease, Chap. XVIII, in <i>American
+Insects</i>, pp. 615&ndash;654, 1905. Discusses Mosquitoes and malaria;
+yellow fever and filariasis.</p>
+
+<p class="hang"><span class="smcap">King, H.H.</span> Report on Economic Entomology of Khartoum, in <i>Third
+Rept. of Wellcome Research Lab.</i>, 1908. Discusses insects injurious
+to man: mosquitoes, blood-sucking insects other than mosquitoes,
+etc.</p>
+
+<p class="hang"><span class="smcap">Mason, C.F.</span> The Spread of Diseases by Insects, with Suggestions
+Regarding Prophylaxis. <i>International Clinics</i>, Vol. II, 1904, pp.
+1&ndash;21. A brief summary of the subject.</p>
+
+<p class="hang"><span class="smcap">McCrae, John.</span> Recent Progress in Tropical Medicine. <i>International
+Clinics</i>, Vol. II, 1904, pp. 22&ndash;36. Discusses several diseases,
+some of which are transmitted by insects.</p>
+
+<p><span class='pagenum'><a name="Page_179" id="Page_179">[Pg 179]</a></span></p><p class="hang"><span class="smcap">Nuttall, G.H.F.</span> On the R&ocirc;le of the Insects Arachnids and Myriapods
+as Carriers in the Spread of Bacterial and Parasitic Diseases of
+Man and Animals. A critical and historical study. <i>Johns Hopkins
+Hospital Reports</i>, Vol. 8, 1899, pp. 1&ndash;154. A review of all the
+literature up to this date. Important article.</p>
+
+<p class="hang"><span class="smcap">Nuttall, G.H.F.</span> Insects as Carriers of Disease. Recent advances in
+our knowledge of the part played by blood-sucking arthropods
+(exclusive of mosquitoes and ticks) in the transmission of
+infectious diseases. Bericht &uuml;ber den XIV. Intern. Kongress f&uuml;r
+Hygiene und Dermogrophic. Berlin, 1907, pp. 195&ndash;206. Discusses
+protozoan and bacterial diseases.</p>
+
+<p class="hang"><span class="smcap">Stiles, C.W.</span> Insects as Disseminators of Disease. <i>Virginia Medical
+Semi-monthly</i>, Vol. 6, No. 3, May 10, 1901, pp. 53&ndash;58. Good
+statement of subject with list of recent workers.</p>
+
+<p class="hang"><span class="smcap">Wherry, W.B.</span> Insects and Infection. <i>Cal. State Jour. of Med.</i>,
+Nov., 1907. Discusses the r&ocirc;le of insects, ticks, etc., in the
+transmission of infectious diseases.</p>
+
+<p class="hang">Symposium on Yellow Fever and Other Insect-borne Diseases.
+<i>Science</i>, N.S., Vol. 23, Nos. 584&ndash;585, 1906. The Protozoan
+Life-cycle, G.N. Calkins. Filariasis and Trypanosome Diseases, H.B.
+Ward. The Practical Results of Reed's Findings on Yellow Fever
+Transmission, J.H. White. Difficulties of Recognition and
+Prevention of Yellow Fever, Q. Kohnke. The Practical Side of
+Mosquito Extermination, H.C. Weeks. Without Mosquitoes There Can Be
+No Yellow Fever, Jas. Carroll. Estivo-autumnal Fever, Cause,
+Diagnosis, Treatment and Destruction of Mosquitoes Which Spread the
+Disease, H.A. Veazie. </p></div>
+
+
+<p class="center">MOSQUITOES&mdash;SYSTEMATIC AND GENERAL</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Balfour, Andrew, and Staff.</span> <i>Second Report of the Wellcome Research
+Laboratories at the Gordon Memorial College</i>, Khartoum,<span class='pagenum'><a name="Page_180" id="Page_180">[Pg 180]</a></span> 1906.
+Includes reports on work on mosquitoes and other noxious insects.</p>
+
+<p class="hang"><span class="smcap">Boyce, Sir Robert W.</span> Mosquitoes or Man? The Conquest of the
+Tropical World. N.Y., 1909. Reviews medical and sanitary work in
+the tropics and discusses the relation of insects to various
+tropical diseases.</p>
+
+<p class="hang"><span class="smcap">Busch, August.</span> Report on a Trip for the Purpose of Studying the
+Mosquito Fauna of Panama. <i>Smith. Miscell. Coll.</i>, Vol. 5, Pt. I,
+1908, p. 49. Work that is being done in Panama to control the
+mosquitoes. Annotated list of species.</p>
+
+<p class="hang"><span class="smcap">Felt, E.P.</span> Mosquitoes or Culicid&aelig; of New York State. In <i>N.Y. State
+Museum Bull. 79</i>, Entomology 22, 1904. Discusses distribution,
+migration and life-history of various species of mosquitoes and
+mosquito diseases. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Giles, Geo. M.</span> A Handbook of Gnats or Mosquitoes, Giving the
+Anatomy and Life-History of the Culicid&aelig;. London, 1902. Whole
+subject treated very fully.</p>
+
+<p class="hang"><span class="smcap">Grubbs, S.B.</span> Vessels as Carriers of Mosquitoes. <i>Pub. Health and
+Mar. Hospt. Ser. Bull.</i> II, Mar. 3, 1903. Believes that mosquitoes
+may come aboard when the vessel is lying at anchor one-half mile
+from shore, and that under favorable conditions they may come
+aboard when the vessel is fifteen miles from shore.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Mosquitoes. <i>Osler's Mod. Med.</i>, Vol. I, p. 370, 1907.
+General notes on classification and habits particularly in relation
+to diseases.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Notes on Mosquitoes of the United States. <i>U.S. Dept.
+Agric., 1900. Div. of Ento. Bull. No. 25</i>, N.S. Account of the
+structure; biology; remarks on remedies.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Concerning the Geographic Distribution of the Yellow
+Fever Mosquito. <i>Public Health Rept., Pub. Health and Mar. Hospt.
+Ser.</i>, Nov. 13, 1903. The same revised to Sept. 10, 1905.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Mosquitoes: How They Live; How They Carry<span class='pagenum'><a name="Page_181" id="Page_181">[Pg 181]</a></span> Disease;
+How They Are Classified; How They May Be Destroyed. N.Y., 1901. One
+of the best popular books on mosquitoes.</p>
+
+<p class="hang"><span class="smcap">McCracken, I.</span> <i>Anopheles</i> in California, with a Description of a
+New Species. <i>Entomological News</i>, Vol. 15, Jan., 1904. Records of
+three species, their breeding-places, habits, etc.</p>
+
+<p class="hang"><span class="smcap">Mitchell, Evelyn G.</span> Mosquito Life. N.Y., 1907. A good popular
+account of the mosquitoes and their relation to disease. The
+appendix treats of mosquitoes and their possible relation to
+leprosy.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> Mosquitoes Occurring Within the State of New Jersey.
+Report of the New Jersey State Agric. Exper. Station upon the
+mosquitoes occurring within the State. Trenton, N.J., 1904. Habits,
+development, relation to disease, checks and remedies; systematic.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> The General Economic Importance of Mosquitoes. <i>Popular
+Science Monthly</i>, 70, 1907, pp. 325&ndash;329. Mosquitoes affect not only
+the health and comfort of the people, but hinder development of
+agriculture and thus affect land values.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> The New Jersey Salt-marsh and Its Improvement. <i>New
+Jersey Agricultural Experiment Station Bulletin</i>, 207, 1907. Shows
+that the increased value of the land drained in the antimosquito
+crusade more than pays for the cost of the drainage.</p>
+
+<p class="hang"><span class="smcap">Theobald, F.V.</span> Monograph of <i>Culicid&aelig;</i> of the World. Four Vols. and
+one Vol. of plates. London, 1901 to 1907. Vol. I contains 96 pages
+on structure, life-history, habits, etc. Vol. II contains a
+bibliography. Vol. Ill contains a list of species that carry
+disease.</p>
+
+<p class="hang"><span class="smcap">Theobald, F.V.</span> Mosquitoes or <i>Culicid&aelig;</i>. In Albutt and Rolleston's
+<i>System of Medicine</i>, II, 1907, pp. 122&ndash;168. Structure,
+life-history, habits, distribution and classification of
+mosquitoes. Bibliography. </p></div>
+
+
+<p><span class='pagenum'><a name="Page_182" id="Page_182">[Pg 182]</a></span></p><p class="center">MOSQUITO ANATOMY</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Berkeley, Wm. M.</span> Laboratory Work with Mosquitoes. N.Y., 1902.
+Chapters on development, anatomy, dissection, malarial parasites,
+filarial disease, yellow fever.</p>
+
+<p class="hang"><span class="smcap">Dimmock, Geo.</span> Anatomy of the Mouth-parts and Suctorial Apparatus of
+<i>Culex</i>. <i>Psyche</i>, 3, pp. 231&ndash;241, Sept., 1881. Good.</p>
+
+<p class="hang"><span class="smcap">Imms, A.D.</span> On the Larval and Pupal Stages of <i>Anopheles
+maculipennis</i>. <i>Journal Hygiene</i>, Vol. 7, No. 2, April, 1907.
+Morphology.</p>
+
+<p class="hang"><span class="smcap">Imms, A.D.</span> On the Larval and Pupal Stages of <i>Anopheles
+maculipennis</i>. <i>Parasitology</i>, Vol. I, No. 2, June, 1908.
+Continuation of article in <i>Jour. Hyg.</i>, Vol. 7, No. 2. Continues
+discussion of morphology.</p>
+
+<p class="hang"><span class="smcap">Nuttall, Geo. F., Corbett, Louis, and Strangeways-Pig, T.</span> Studies
+in Relation to Malaria. Pt. I, The Geographical Distribution of
+<i>Anopheles</i> in Relation to the Former Distribution of Ague in
+England. <i>Jour. Hyg.</i>, Vol. I, No. 1, Jan., 1901.</p>
+
+<p class="hang"><span class="smcap">Nuttall, Geo. F., and Shipley, Arthur E.</span> Studies in Relation to
+Malaria. Pt. II, Structure and Biology of <i>Anopheles</i>, <i>Jour Hyg.</i>,
+Vol. I, No. 1, Jan., 1901: The Egg and Larva; Bibliography. Pt. II,
+cont, Vol. I, No. 2, April, 1901: The Pupa. Pt. II, cont., Vol. I,
+No. 4, Oct., 1901: Adult External Anatomy. Pt. II, cont., Vol. 2,
+No. 1, Jan., 1902: &AElig;tiology of Adult. Pt. II, cont., Vol. Ill, No.
+2, April, 1903: Anatomy of Adult.</p>
+
+<p class="hang"><span class="smcap">Thompson, Millett T.</span> Alimentary Canal of the Mosquito. <i>Proc. Bost.
+Soc. Nat. Hist.</i>, Vol. 32, No. 6, 1905, pp. 145&ndash;202. Good summary
+of recent investigations.</p>
+
+<p class="hang"><span class="smcap">Wesche, W.</span> The Mouth-parts of <i>Nemocera</i> and Their Relation to the
+Other Families of <i>Diptera</i>. <i>Royal Microscopic Soc. Jour.</i>, 1904,
+pp. 28&ndash;47. Discussion with illustrations of the mouth-parts of
+various <i>Diptera</i>. </p></div>
+
+
+<p><span class='pagenum'><a name="Page_183" id="Page_183">[Pg 183]</a></span></p><p class="center">MOSQUITOES&mdash;LIFE-HISTORY AND HABITS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Ayers, E.A.</span> The Secrets of the Mosquito. A guide to the
+extermination of the prolific pest. <i>World's Work</i>, 1907, Vol. 14,
+pp. 8902&ndash;8910. Notes on life-history and methods of control.</p>
+
+<p class="hang"><span class="smcap">Jordan, E.O., and Hefferan, Mary.</span> Observations on the Bionomics of
+<i>Anopheles</i>. <i>Jour. Infec. Diseases</i>, II, 1905, pp. 56&ndash;69.
+Occurrence, breeding-places, habits, etc.</p>
+
+<p class="hang"><span class="smcap">Morgan, H.A., and Dupree, J.W.</span> Development and Hibernation of
+Mosquitoes. <i>Bull. 40</i>, N.S., <i>Div. of Ento.</i>, pp. 88&ndash;92, 1903.
+Results of observation on five genera of mosquitoes in the vicinity
+of Baton Rouge, La.</p>
+
+<p class="hang"><span class="smcap">Ross, E.H.</span> The Influence of Certain Biological Factors on the
+Question of the Migration of Mosquitoes. <i>Jour. Trop. Med. &amp; Hyg.</i>,
+12, 1909, pp. 256&ndash;258, Sept. 1. Only fecundated females feed on
+blood, and must be fertilized after each batch of eggs. This
+determines largely the time and place of breeding.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> Concerning Migration of Mosquitoes. <i>Science</i>, 18, Dec.
+11, 1903, pp. 761&ndash;764. Observations on the migrations of
+mosquitoes, particularly <i>C. sollicitans</i>. </p></div>
+
+
+<p class="center">MOSQUITO FIGHTING</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Celli, Angelo.</span> The Campaign Against Malaria in Italy. Transl. by
+J.J. Eyre. <i>Jour. Trop. Med. &amp; Hyg.</i>, XI, Apr. 1, 1908, pp.
+101&ndash;108. Includes a good discussion of the effectiveness of
+destroying the mosquitoes in controlling malaria.</p>
+
+<p class="hang"><span class="smcap">Felt, E.P.</span> Mosquito Control. In <i>Report of the N.Y. State
+Entomologist for 1905</i>, pp. 109&ndash;116. Notes on importance and
+methods of control of various species.</p>
+
+<p class="hang"><span class="smcap">Goldberger, Jos.</span> Prevention and Destruction of Mosquitoes. <i>Public
+Health Reports, Pub. Health and Mar. Hospt. Ser.</i>,<span class='pagenum'><a name="Page_184" id="Page_184">[Pg 184]</a></span> July 17, 1908.
+Life-histories and methods of fighting larv&aelig;, pup&aelig; and adults.</p>
+
+<p class="hang"><span class="smcap">Le Prince, J.A.</span> Mosquito Destruction in the Tropics. <i>Jour. Amer.
+Med. Assn.</i>, LI, p. 26, Dec. 26, 1908. Occurrence and habits of
+<i>Anopheles</i>, methods of destruction. Results of anti-malarial work
+on the isthmus. Discussion by various doctors.</p>
+
+<p class="hang"><span class="smcap">Quayle, H.J.</span> Mosquito Control Work in California. <i>Bull. No. 178,
+Calif. Agric. Ex. Sta.</i>, pp. 1&ndash;55, 1906. Habits and life-history of
+California species, with an account of experiments to control the
+salt-marsh species.</p>
+
+<p class="hang"><span class="smcap">Rosenan, M.J.</span> Disinfection Against Mosquitoes with Formaldehyde and
+Sulphur Dioxid. <i>Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull.
+6</i>, 1901.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> Mosquito Brigades and How to Organize Them. New York,
+1902.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> Logical Basis of the Sanitary Policy of Mosquito
+Reduction. <i>Science</i>, N.S., Vol. 22, No. 750, Dec. 1, 1905, pp.
+689&ndash;699. Important article dealing with the methods of control.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> Salt-marsh Mosquitoes. <i>New Jersey Agric. Exper. Stn.
+Special Bulletin T</i>, 1902. Breeding-places and methods of control
+of this species.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> Mosquitocides. <i>Bull. 40, New Series U.S. Dept. Agric.,
+Div. of Ento.</i>, pp. 96&ndash;108, 1903. Results of experiments with a
+number of substances, several of which were found to be effective
+and some cheap enough to permit of their use to a limited extent.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> The New Jersey Salt-marsh and Its Improvement. <i>Bull.
+No. 207</i>, Nov. 14, 1907, <i>New Jersey Agric. Exper. Stn.</i> Results of
+draining the marshes to get rid of mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> The House Mosquito: a City, Town and Village Problem.
+<i>N.J. Agric. Ex. Stn. Bull. 216</i>, 1908. Work done<span class='pagenum'><a name="Page_185" id="Page_185">[Pg 185]</a></span> on salt-marshes
+since 1904 practically eliminated the migratory species, so that
+<i>C. pipens</i>, the house mosquito, is now the problem. Life-history
+and methods of combating.</p>
+
+<p class="hang"><span class="smcap">Underwood, W.L.</span> Mosquitoes and Suggestions for Their Extermination.
+<i>Pop. Sci. Mo.</i>, Vol. 63, 1903, pp. 453&ndash;466. Life-history, habits
+and methods of control.</p>
+
+<p class="hang"><span class="smcap">Underwood, W.L.</span> The Mosquito Nuisance and How to Deal with It.
+Boston, 1903.</p>
+
+<p class="hang">First Antimosquito Convention, 1903. Pub., Brooklyn, 1904. Contains
+articles on what railroads, government and laws should do toward
+mosquito extermination; mosquito work in Havana; how state
+appropriations should be used, etc.</p>
+
+<p class="hang">National Mosquito Extermination Society. Bulletin No. 1, 1904.
+Object of Society; brief sketches of Ross, Reed, and others.
+Reprints of a few articles on mosquito extermination.</p>
+
+<p class="hang">American Mosquito Extermination Society. <i>Year Book for 1904&ndash;05.</i>
+N.Y., 1906. Containing reports of meetings and discussions of
+various problems. Several interesting papers, among them "Criminal
+Indictment of the Mosquito," F.W. Moss. "Mosquito Work at Panama
+Canal," W.C. Sorgas. "Diversities Among New York Mosquitoes," E.P.
+Felt. "Mosquito Extermination in New Jersey," J.B. Smith. "The
+Mosquito Question," Quitman Kohnke.</p>
+
+<p class="hang">Antimalarial Work in the Panama Canal Zone. Editorial in <i>Jour.
+Trop. Med. &amp; Hyg.</i>, XI, Aug. 15, 1908, p. 251. Notes on the success
+of the measures adopted there. </p></div>
+
+
+<p class="center">MOSQUITOES AND DISEASE</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Doty, A.H.</span> The Mosquito, Its Relation to Disease and Its
+Extermination. <i>New York State Journal of Medicine</i>, May, 1908.</p>
+
+<p class="hang"><span class="smcap">Finlay, Chas.</span> Mosquitoes Considered as Transmitters of Yellow Fever
+and Malaria. <i>Med. Record</i>, May 27, 1899,<span class='pagenum'><a name="Page_186" id="Page_186">[Pg 186]</a></span> pp. 737&ndash;739. Review of
+his theory in regard to mosquitoes and disease and the probable
+necessary changes in view of recent discoveries.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Mosquitoes as Transmitters of Disease. <i>Review of
+Reviews</i>, XXIV, 1901, pp. 192&ndash;195. A review of the work of various
+investigators.</p>
+
+<p class="hang"><span class="smcap">Smith, J.B.</span> Sanitary Aspect of the Mosquito Question. <i>Medical
+News</i>, Mar. 7, 1903. Note on mosquitoes and their relation to
+disease.</p>
+
+<p class="hang"><span class="smcap">Taylor, J.B.</span> Observations on the Mosquitoes of Havana, Cuba.
+Reprint from <i>La Revista de Medicina</i>, June, 1903, p. 27. </p></div>
+
+
+<p class="center">MALARIA</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Banks, C.S.</span> Experiments in Malarial Transmission by Means of
+<i>Myzomyia ludlowii</i>. <i>Phil. Jour. Sci.</i>, B. 2, 1907, pp. 513&ndash;535.
+Breeding-places of mosquitoes, life-histories of the species;
+mosquitoes and malaria.</p>
+
+<p class="hang"><span class="smcap">Craig, C.F.</span> Malarial Fevers. <i>Osler's Mod. Med.</i>, Vol. I, p. 392,
+1907. Historical; distribution; malarial parasites; classification;
+development; malarial mosquitoes; pathology; treatment, etc.</p>
+
+<p class="hang"><span class="smcap">Craig, C.F.</span> Studies in the Morphology of Malarial Plasmodia after
+the Administration of Quinine and in Intracorpuscular Conjugation.
+<i>Jour. Infec. Diseases</i>, VII, No. 2, 1910. See also same, IV, 1907,
+pp. 108&ndash;140. Gives the evidence upon which he bases his theory of
+the meaning of intracorpuscular conjunction.</p>
+
+<p class="hang"><span class="smcap">Craig, C.F.</span> The Malarial Fevers, Hemoglobinuric Fever and the Blood
+Protozoa of Man. N.Y., 1909. A thorough consideration of the
+subject of malaria and good discussion of the other subjects noted
+in title. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Deaderick, W.H.</span> Malaria. Philad., 1909. The chapter on &aelig;tiology
+treats of the transmission by mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Harris, S.</span> Prevention of Malaria. <i>Jour. Amer. Med. Assn.</i>, 53,<span class='pagenum'><a name="Page_187" id="Page_187">[Pg 187]</a></span>
+Oct. 9, 1909, pp. 1162&ndash;67. Effects of malaria, transmission by
+mosquitoes, etc. In the discussion of the paper J.H. White
+summarizes the fight against yellow fever in New Orleans.</p>
+
+<p class="hang"><span class="smcap">Herrick, G.W.</span> Relation of Malaria to Agriculture and Other
+Industries of the South. Economic losses occasioned by malaria;
+malaria responsible for more sickness among the white population
+than any other disease; relation to mosquitoes. <i>Pop. Sci. Mo.</i>,
+Vol. 62, Apr., 1903, pp. 521&ndash;525.</p>
+
+<p class="hang"><span class="smcap">Jones, Ross, Ellett.</span> Malaria. London, 1907. Small book,
+introduction by Ross. Malaria in Greece and Italy; shows how this
+disease contributed to the downfall of great nations.</p>
+
+<p class="hang"><span class="smcap">Mannaberg, Julius.</span> Malaria. In Nothnagel's <i>Encyclopedia of
+Practical Med.</i>, Amer. Ed., 1905, pp. 17&ndash;494. A very comprehensive
+discussion of the disease and the relation of mosquitoes to the
+malarial parasite.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> The Mosquito and the Malaria Parasite. <i>Brit. Med.
+Jour.</i>, Vol. II for 1898, pp. 849&ndash;853. History of the parasite in
+the human and insect host; observations of Ross and others and
+their meaning.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Experimental Demonstration of the
+Mosquito-malarial Theory. <i>Brit. Med. Jour.</i>, Vol. 2 for 1900, pp.
+949&ndash;951, also <i>Lancet</i>, II, 1900, pp. 923&ndash;925. Infected mosquitoes
+sent from Rome allowed to bite men in England who had not been in
+malarial regions. Malarial fever followed.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Malarial Fever. Appendix to Vol. IX of T.C.
+Albutt's <i>System of Med.</i>, 1900. Relation of the malarial parasite
+to the disease and to mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Robertson, E.W.</span> Renaming of Malaria&mdash;Anophelesis. <i>Va. Medical
+Semi-monthly</i>, Sept. 10, 1909. Considers malaria a misnomer and
+gives reasons for suggesting new name.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> On Some Peculiar Pigmented Cells Found in Two
+Mosquitoes Fed on Malarial Blood. <i>Brit. Med. Jour.</i>, 1897, Dec.
+18, p. 1786. Records in his experiments in feeding<span class='pagenum'><a name="Page_188" id="Page_188">[Pg 188]</a></span> mosquitoes on
+blood of malarial patients. Records finding the parasites in some
+of them. Important article.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> Pigmented Cells in Mosquitoes. <i>Brit. Med. Jour.</i>,
+1898, Feb. 26, p. 550. Further notes on them.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> The Mosquito Theory of Malaria. Report dated
+Calcutta, Feb. 16, 1899. Reprinted in <i>Pop. Sci. Monthly</i>, Vol. 56,
+Nov., 1899, pp. 42&ndash;46. Tells of his investigations in India and
+their results.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> The Relationship of Malaria and the Mosquito.
+<i>Lancet</i>, II, 1900, July 7, p. 4880. Observation on the
+transmission of malaria.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> Malaria Fever, Its Cause, Prevention and Treatment.
+London, 1902. Chapters on malaria, mosquitoes, prevention and
+treatment.</p>
+
+<p class="hang"><span class="smcap">Ross, Ronald.</span> Parasites of Mosquitoes. <i>Jour. of Hyg.</i>, VI, No. 2,
+Apr., 1906. Brief review of several of his earlier papers on this
+subject with additional notes.</p>
+
+<p class="hang"><span class="smcap">Simpson, W.J.R.</span> Recent Discoveries Which Have Rendered Antimalarial
+Sanitation More Precise and Less Costly. <i>Brit. Med. Jour.</i>, 1907,
+II, pp. 1044&ndash;46. Discussion of the various factors in mosquito
+control.</p>
+
+<p class="hang"><span class="smcap">Stephens, J.W.W., and Christophers, S.R.</span> The Practical Study of
+Malaria and Other Blood Parasites. London, 1908. Chapters on
+mosquitoes, flies and ticks and their relation to diseases.</p>
+
+<p class="hang"><span class="smcap">Sternberg, G.M.</span> The Malarial Parasite and Other Pathogenic
+Protozoa. <i>Pop. Sci. Mo.</i>, Vol. 50, 1897, pp. 628&ndash;641. Account of
+the discovery of the malarial parasite and more recent studies on
+it.</p>
+
+<p class="hang"><span class="smcap">Sternberg, G.M.</span> Malaria. <i>Smith. Rept.</i>, 1900, pp. 645&ndash;656. Review
+of the experimental evidence in support of the mosquito-malaria
+theory.</p>
+
+<p class="hang">Malarial Fever. <i>Jour. Trop. Med. &amp; Hyg.</i>, II, Mar. 16, 1908, pp.
+96&ndash;98. A list of literature mostly for the years 1906 and 1907. </p></div>
+
+
+<p><span class='pagenum'><a name="Page_189" id="Page_189">[Pg 189]</a></span></p><p class="center">YELLOW FEVER</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Adams, S.H.</span> Yellow Fever, a Problem Solved. The battle of New
+Orleans against the mosquito. <i>McClure's Magazine</i>, Vol. 27, June,
+1906, p. 178. An interesting popular article.</p>
+
+<p class="hang"><span class="smcap">Carroll, James.</span> Yellow Fever. <i>Osler's Mod. Med.</i>, Vol. II, 1907,
+p. 736. History, &aelig;tiology, treatment. A good review of the work of
+the Yellow Fever Com. and the results of their work.</p>
+
+<p class="hang"><span class="smcap">Carroll, James.</span> The Transmission of Yellow Fever. <i>Amer. Med.
+Assn.</i>, 40, 1905, pp. 1429&ndash;33. Shows the relation of the mosquito
+to the disease.</p>
+
+<p class="hang"><span class="smcap">Carroll, James.</span> Yellow Fever. Lessons to be learned from the
+present outbreak of yellow fever. <i>Jour. of Amer. Med. Assn.</i>, Vol.
+45, 1905, pp. 1079&ndash;81. Among other things recommends that
+mosquitoes be kept from patients.</p>
+
+<p class="hang"><span class="smcap">Chaille, S.E.</span> The <i>Stegomyia</i> and Fomites. <i>Amer. Med. Assn.</i>, 40,
+1903, pp. 1433&ndash;40. Concludes that the mosquito is the only proven
+disseminator of yellow fever. Extended discussion by various
+physicians.</p>
+
+<p class="hang"><span class="smcap">Dastre, A.</span> The Fight Against Yellow Fever. <i>Smith. Rept.</i>, 1905,
+pp. 339&ndash;350. History of the yellow fever epidemics, its
+geographical distribution, and the work that is being done to
+control it.</p>
+
+<p class="hang"><span class="smcap">Doty, A.H.</span> On the Mode of Transmission of the Infectious Agent in
+Yellow Fever and Its Bearing upon the Quarantine Regulations. <i>Med.
+Record</i>, Oct. 26, 1901, pp. 649&ndash;653. Review of older theories in
+regard to the spread of yellow fever. Believes that the quarantines
+are now unnecessary.</p>
+
+<p class="hang"><span class="smcap">Finley, Chas.</span> The Mosquito Theory of the Transmission of Yellow
+Fever and Its New Development. <i>Med. Record</i>, Jan. 19, 1901. Refers
+to his early observations on the subject, giving extracts from some
+of his earlier papers to show that he had long held the mosquito
+responsible for the dissemination of yellow fever.</p>
+
+<p><span class='pagenum'><a name="Page_190" id="Page_190">[Pg 190]</a></span></p><p class="hang"><span class="smcap">Goldberger, Jos.</span> Yellow Fever, &AElig;tiology, Symptoms and Diagnosis.
+<i>Yellow Fever Inst. Bull. 16, Pub. Health and Mar. Hospt. Ser.</i>,
+1907. Includes discussion of the relation of mosquitoes to the
+disease.</p>
+
+<p class="hang"><span class="smcap">Guiteras, John.</span> Experimental Yellow Fever at the Inoculation
+Station of the Sanitary Department of Havana. <i>Amer. Med.</i>, Vol.
+II, No. 21, 1901, pp. 809&ndash;817. Experiments show that all types of
+the yellow fever from mild to severe may be produced by the bite of
+the mosquito.</p>
+
+<p class="hang"><span class="smcap">McFarland, Joseph.</span> Life and Work of James Carroll. Memoir read at
+the fifth annual meeting of the Soc. of Tropical Med., 1908. Early
+life of Carroll and his work with the Yellow Fever Com.</p>
+
+<p class="hang"><span class="smcap">Parker, H.B., Beyer, G.E., and Pothier, O.L.</span> Rept. of Working Party
+No. 1, Yellow Fever Institute. <i>Bull. 13, Pub. Health and Mar.
+Hospt. Ser.</i>, 1903. As a result of their studies they believe that
+the disease is caused by a protozoan parasite which they name and
+describe. Discuss the relation of mosquitoes to the disease.</p>
+
+<p class="hang"><span class="smcap">Reed, Walter; Carroll, James; and Agramonte, A.</span> Experimental Yellow
+Fever. <i>Amer. Med.</i>, July 6, 1901, pp. 15&ndash;23. Records of certain
+experiments and their results.</p>
+
+<p class="hang"><span class="smcap">Reed, Walter; Carroll, James; and Agramonte, C.A.</span> The &AElig;tiology of
+Yellow Fever. A preliminary note presented at the Amer. Pub. Health
+Assn. <i>Philad. Med. Jour.</i>, Oct. 27, 1900, pp. 790&ndash;796. Also an
+additional note in <i>Jour. Amer. Med. Assn.</i>, 36, pp. 431&ndash;440, 1901.
+Records of their experiments and a summing up of the data in regard
+to yellow fever and the mosquito.</p>
+
+<p class="hang"><span class="smcap">Reed, Walter, and Carroll, James.</span> The Prevention of Yellow Fever.
+<i>Med. Record</i>, Oct. 26, 1901, pp. 441&ndash;449. History of the disease,
+especially in U.S., results of the work of Yellow Fever Com.
+description, life-history and habits of the mosquito, its relation
+to yellow fever, methods of control. Important paper.</p>
+
+<p><span class='pagenum'><a name="Page_191" id="Page_191">[Pg 191]</a></span></p><p class="hang"><span class="smcap">Reed, Walter.</span> Recent Researches Concerning the &AElig;tiology,
+Propagation and Prevention of Yellow Fever by U.S. Army Com. <i>Jour.
+Hyg.</i>, 2, 1902, pp. 101&ndash;119. Review of work of the Yellow Fever
+Com. and the importance of the results. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Rosenan, M.J., Parker, H.B., Francis, E., and Beyer, G.E.</span> Rept. of
+Working Party No. 2, Yellow Fever Institute. Experimental studies
+in yellow fever and malaria at Vera Cruz, Mex. <i>U.S. Pub. Health
+and Mar. Hospt. Ser.</i>, May, 1904. Includes experiments and
+observations on mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Rosenan, M.J., and Goldberger, Jos.</span> Report of Working Party No. 3,
+Yellow Fever Institute. <i>Yellow Fever Inst. Bull. 15, Pub. Health
+and Mar. Hospt. Ser.</i>, 1906. Unsuccessful attempts to grow the
+yellow fever parasite. Negative results in the experimental study
+of the hereditary transmission of the yellow fever in the mosquito.
+Appendix A gives a translation of Marchoux and Simonds' report in
+which they report positive results in their experiments along the
+same line.</p>
+
+<p class="hang"><span class="smcap">Sternberg, G.M.</span> Transmission of Yellow Fever by Mosquitoes. <i>Smith.
+Rept.</i>, 1900, pp. 657&ndash;673. Review of the early theories in regard
+to yellow fever and the work and findings of the yellow fever
+commission.</p>
+
+<p class="hang"><span class="smcap">White, J.H.</span> Yellow Fever and the Mosquito. <i>Jour. Amer. Med.
+Assn.</i>, LI, No. 26, Dec. 26, 1908. Considers both <i>S. calopus</i> and
+<i>C. pungens</i>. Results of early mistakes. Necessity of destroying
+mosquito. Methods of destroying mosquito. Habits of mosquito.</p>
+
+<p class="hang">Abstract of the Report of the French Yellow Fever Com. at Rio de
+Janeiro, 1903. <i>Pub. Health Report, Pub. Health and Mar. Hospt.
+Ser.</i>, Vol. 19, Pt. I, p. 1019. A summary of their findings and
+conclusions to the date of report.</p>
+
+<p class="hang"><span class="smcap">de Ybarra, A.M.F.</span> Yellow Fever Again in Cuba. <i>Jour. Trop. Med. &amp;
+Hyg.</i>, XI, Mar. 2, 1908, pp. 73&ndash;78. Cites a number of cases of
+yellow fever within the last few years and<span class='pagenum'><a name="Page_192" id="Page_192">[Pg 192]</a></span> uses them as evidence
+to show that the disease may be transmitted in other ways than by
+the mosquito. A strong summing up of the arguments against the
+mosquito theory. Reprint of editorial in <i>Tex. Med. Jour.</i>, Oct.,
+1907, also follows this article.</p>
+
+<p class="hang">The Extinction of Yellow Fever at Rio de Janeiro. <i>Lancet</i>, II,
+1909, p. 404. A review of a French publication giving the results
+of the work from 1903 to present time. In 1903 before work was
+begun there were 584 deaths from yellow fever. In 1908 only 4, and
+none so far in 1909. Success accredited to mosquito work and
+general sanitation.</p>
+
+<p class="hang">A Pioneer in Research on Yellow Fever. Editorial in <i>Brit. Med.
+Jour.</i>, May 30, 1908, p. 1306. Refers to the work of L.D.
+Beauperthuy, who, in 1853, set forth the theory that yellow fever
+was transmitted by mosquitoes. </p></div>
+
+
+<p class="center">DENGUE</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Ashburn, P.M., and Craig, C.F.</span> Experimental Investigations
+Regarding the &AElig;tiology of Dengue Fever. <i>Jour. Infec. Diseases</i>,
+Vol. V, 1907, pp. 440&ndash;475. Conclude that the disease is spread only
+by mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Coleman, Thomas D.</span> Dengue. <i>Osler's Mod. Med.</i>, Vol. II, 1907, p.
+489. &AElig;tiology, pathology, etc.; possibility of <i>Culex fatigans</i>
+disseminating the disease.</p>
+
+<p class="hang"><span class="smcap">Graham, H.</span> "The Dengue"; a Study of Its Pathology and Mode of
+Propagation. <i>Jour. of Trop. Med. &amp; Hyg.</i>, July 1, 1903, p. 209.
+Experiments which seem to show that dengue is transmitted by <i>Culex
+fatigans</i>.</p>
+
+<p class="hang"><span class="smcap">Leichtenstern, O.</span> Dengue. In Nothnagel's <i>Encyclopedia of Practical
+Med.</i>, Amer. Ed., 1905, pp. 720&ndash;743. Consideration of the disease
+and its transmission.</p>
+
+<p class="hang"><span class="smcap">Ross, E.H.</span> The Prevention of Dengue Fever. <i>Amer. Trop. Med. &amp;
+Parasit.</i>, Vol. II, No. 3, July 1, 1908, pp. 193&ndash;195.<span class='pagenum'><a name="Page_193" id="Page_193">[Pg 193]</a></span> A successful
+campaign against the mosquitoes in Port Said in 1906 stopped the
+outbreaks of malaria and dengue.</p>
+
+<p class="hang">Dengue and Sand-flies. <i>Jour. Trop. Med. &amp; Hyg.</i>, 12, 1909, pp.
+172&ndash;173. A note on these pages refers to the work of Dr. R. Doerr,
+who suspects that dengue may be carried by sand-flies,
+<i>Phlobotomus</i>, as well as by mosquitoes. </p></div>
+
+
+<p class="center">FILARIAL DISEASES AND ELEPHANTIASIS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Christophers, S.R.</span> What Is Really Known of the Cause of
+Elephantiasis. <i>Ind. Med. Gaz.</i>, Nov., 1907, p. 404. Questions
+Manson's theory in regard to the disease being caused by filaria.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Tropical Diseases. London, 1908, pp. 594&ndash;648. A
+most comprehensive chapter on filariasis and elephantiasis.</p>
+
+<p class="hang"><span class="smcap">Phalen, J.M., and Nichols, H.J.</span> Filariasis and Elephantiasis in
+Southern Luzon. <i>Phil. Jour. Sci.</i>, Sept., 1908. <i>Culex
+microannulatus</i> regarded as the carrier of the filaria.</p>
+
+<p class="hang"><span class="smcap">Prout, W.T.</span> On the R&ocirc;le of Filaria in the Production of Disease.
+<i>Jour. Trop. Med. &amp; Hyg.</i>, Apr. 1, 1908, p. 109. Discussion of same
+in same journal, June 1, 1908.</p>
+
+<p class="hang"><span class="smcap">White, Duncan.</span> Filarial Periodicity and Its Association with
+Eosinophilia. <i>Jour. Trop. Med. &amp; Hyg.</i>, 12, July 15, 1909, pp.
+175&ndash;183. Among other things he discusses the relation of mosquitoes
+to filarial diseases. </p></div>
+
+
+<p class="center">LEPROSY</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Brinckerhoff, W.R.</span> A Note upon the Possibility of the Mosquito
+Acting in the Transmission of Leprosy. <i>Pub. Health and Mar. Hospt.
+Ser.</i> (general publications), 1908. Suggests the possibilities of
+such transmission, but concludes that the probabilities are against
+it.</p>
+
+<p class="hang"><span class='pagenum'><a name="Page_194" id="Page_194">[Pg 194]</a></span></p><p class="hang"><span class="smcap">Goodhue, E.S.</span> The Bacillus Lepr&aelig; in the Gnat and Bedbug. <i>Ind.
+Med. Gaz.</i>, Vol. XLI, Aug., 1906, p. 342. Has found this bacillus
+in mosquitoes and bedbugs, but believes the latter is more
+concerned in transmitting the disease.</p>
+
+<p class="hang"><span class="smcap">Goodhue, E.S.</span> Mosquitoes and Their Relation to Leprosy in Hawaii.
+<i>Amer. Med.</i>, N.S., 2, 1907, p. 593. Suggests that mosquitoes may
+carry the disease, also warns against danger from flies and
+bedbugs.</p>
+
+<p class="hang"><span class="smcap">Hutchinson, J.</span> Mosquitoes and Leprosy. <i>Brit. Med. Jour.</i>, Dec. 22,
+1906, Vol. II, p. 1841. Evidence against the insect theory of
+transmission of leprosy.</p>
+
+<p class="hang"><span class="smcap">Mugliston, T.C.</span> On a Possible Mode of Communication of Leprosy.
+<i>Jour. Trop. Med.</i>, Vol. VIII, July 15, 1905, p. 209. Suggests that
+the itch-mite may be the carrier of leprosy. Studies on 77 lepers
+led him to this conclusion.</p>
+
+<p class="hang"><span class="smcap">Smyth, W.R.</span> Leprosy. <i>Brit. Med. Jour.</i>, Dec. 8, 1906, Vol. II, p.
+1670. Believes that bedbugs or some similar wingless parasite
+conveys the disease. </p></div>
+
+
+<p class="center">PLAGUE</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Brannerman, W.B.</span> Spread of Plague in India. <i>Jour. of Hyg.</i>, Vol.
+6, No. 2, Apr., 1906, pp. 179&ndash;211. A digest of experiments made in
+India. Discusses various ways in which the disease may be spread.
+Review of the evidence that insects may be concerned. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Calvert, W.J.</span> Plague. <i>Osler's Mod. Med.</i>, Vol. II, 1907, p. 760.
+History; bacteriology; pathology; plague among animals;
+transmission, etc.</p>
+
+<p class="hang"><span class="smcap">Ham, B. Burnett.</span> Report on Plague in Queensland, 1900&ndash;1907. P. 153
+discusses the rat-flea theory of dissemination of bubonic plague,
+summing up the evidence of various observers, including the Indian
+Advisory Com. and others. Considers the evidence conclusive that
+<i>P. cheopis</i> and possibly <i>C. fasciatus</i><span class='pagenum'><a name="Page_195" id="Page_195">[Pg 195]</a></span> transmit plague. Other
+pages discuss various rat fleas and their relation to plague in
+rats.</p>
+
+<p class="hang"><span class="smcap">Hankin, E.H.</span> On the Epidemiology of Plague. <i>Jour. Hyg.</i>, 5, 1905,
+pp. 48&ndash;83. A comprehensive discussion of the disease and its
+spread, several pages devoted to rats and fleas; evidence for and
+against the theory that rats and fleas are the principal carriers
+of the disease.</p>
+
+<p class="hang"><span class="smcap">Herzog, Max.</span> The Plague, Bacteriology, Morbid Anatomy &amp;
+Histopathology, Including the Consideration of Insects as Plague
+Carriers. Biological Laboratory Bureau of Govt. Laboratories,
+Manila, Oct., 1904. Reviews the evidence regarding the possibility
+of fleas carrying plague; describes a new rat flea (<i>Pulex
+philippinensis</i>); records experiments with fleas and cites a case
+of bubonic plague in a child in which the infection was possibly
+carried by <i>Pediculi</i>.</p>
+
+<p class="hang"><span class="smcap">McCoy, G.W.</span> Plague Bacilli in Ectoparasites of Squirrels. <i>Pub.
+Health Reports, Pub. Health and Mar. Hospt. Ser.</i>, Vol. XXIV, No.
+16, Apr. 16, 1909. Experiments with fleas and lice from infected
+squirrels demonstrating presence of plague bacilli.</p>
+
+<p class="hang"><span class="smcap">McCoy, G.W.</span> The Susceptibility of Gophers, Field-mice and
+Ground-squirrels to Plague Infection. <i>Jour. of Infec. Diseases</i>,
+Vol. 6, 1909, No. 3, pp. 283&ndash;288. Gophers highly resistant,
+field-mice moderately susceptible and ground-squirrels very
+susceptible to plague.</p>
+
+<p class="hang"><span class="smcap">Mitzmain, M.B.</span> Insect Transmission of Bubonic Plague: a Study of
+the San Francisco Epidemic. <i>Ento. News</i>, 19, No. 8, 1908, pp.
+353&ndash;359. Fleas obtained in examination of 1,800 rats. Attempt to
+locate source of rat and flea introduction.</p>
+
+<p class="hang"><span class="smcap">Morton, F.M.</span> Eradicating Plague from San Francisco. Report of the
+Citizens' Health Com. and an account of its work. San Francisco,
+1909. Discusses the epidemics, methods of transmission, methods of
+fighting, etc.</p>
+
+<p><span class='pagenum'><a name="Page_196" id="Page_196">[Pg 196]</a></span></p><p class="hang"><span class="smcap">Rucker, W.C.</span> Plague Among Ground-squirrels in Contra Costa Co.,
+Cal. <i>Pub. Health Reports, Pub. Health and Mar. Hospt. Ser.</i>, Aug.
+27, 1909. Reports of human cases supposed to be connected with
+plague among ground-squirrels. Plague among squirrels; habits,
+methods of fighting, etc.</p>
+
+<p class="hang"><span class="smcap">Rucker, W.C.</span> Fighting an Unseen Foe. <i>Sunset Mag.</i>, XXII, No. 2,
+Feb., 1909. Story of the fight against plague in San Francisco.</p>
+
+<p class="hang"><span class="smcap">Shipley, A.E.</span> Rats and Their Animal Parasites. <i>Jour. Eco.
+Biology</i>, Vol. III, No. 3, Oct. 28, 1908. List of species of ecto-
+and endoparasites.</p>
+
+<p class="hang"><span class="smcap">Simpson, W.J.</span> A Treatise on Plague. Cambridge Univ. Press, London,
+1906. Deals with historical, epidemiological, clinical, therapeutic
+and preventive aspect of the disease.</p>
+
+<p class="hang"><span class="smcap">Thompson, J.A.</span> The Mode of Spread and Prevention of Plague in
+Australia. <i>Lancet</i>, Oct. 19, 1907, p. 1104. Rat fleas the
+essential factor in transmitting plague, and preventive methods
+should be directed against the rats.</p>
+
+<p class="hang"><span class="smcap">Thompson, J.A.</span> On the Epidemiology of Plague. <i>Jour. Hyg.</i>, Vol.
+VI, No. 5, Oct., 1906. Methods of infection, spread, relation of
+rats to the disease and a review of the rat-flea theory.
+Bibliography.</p>
+
+<p class="hang"><span class="smcap">Verjbitski, D.T.</span> The Part Played by Insects in the Epidemiology of
+Plague. <i>Jour. Hyg.</i>, 8, 1908, No. 2, pp. 162&ndash;208. Record of
+extensive experiments with fleas. Fleas communicated plague for
+three days, bedbugs for five days. Interrelation of fleas, rats,
+dogs, cats, and man. An important article translated from Russian.</p>
+
+<p class="hang"><span class="smcap">Wherry, W.B.</span> Further Notes on the Rat Leprosy and on the Fate of
+the Human and Rat Leper Bacillus in Flies. <i>Jour. Infec. Diseases</i>,
+Vol. 5, No. 5, 1908. Discussion and references, experiments with
+flies, summary, etc. More than 1,115 lepra-like bacilli were
+counted in a single fly-speck.</p>
+
+<p class="hang"><span class="smcap">Wherry, W.B.</span> Plague Among the Ground-squirrels of California.<span class='pagenum'><a name="Page_197" id="Page_197">[Pg 197]</a></span>
+<i>Jour. Infec. Diseases</i>, Vol. 5, No. 5, 1908, pp. 485&ndash;533. How the
+plague was first discovered among rats, records of cases and a
+discussion of the possible relation of this to human plague cases.</p>
+
+<p class="hang">Eradicating Plague in San Francisco; Report of the Citizens' Health
+Committee, 1909. An account of the recent outbreaks and the methods
+of fighting them.</p>
+
+<p class="hang">Report of the Indian Plague Commission, Vol. V, pp. 75&ndash;77, 1901. In
+these pages the Commission considers the question of the
+transference of plague by suctorial insects. It considers Simonds'
+claims and others and believes that "suctorial insects do not come
+under consideration with the spread of plague."</p>
+
+<p class="hang">Reports on Plague Investigations in India Issued by the Advisory
+Committee Appointed by the Sec. of State for India, the Royal
+Society and the Lister Institute. The reports include the reports
+of the Working Commission appointed by the Advisory Committee and
+reports on various contributory investigations. They are published
+in the <i>Jour. of Hygiene</i> as "Extra Plague Numbers." All these
+reports deal very largely with the relation of the rat and flea to
+plague, and are commonly referred to as "Reports of Indian Plague
+Commission." The first number, Vol. VI, Sept., 1906, contains
+articles on "Experiments upon the Transmission of Plague by Fleas."
+"Note on the Species of Fleas Found on Rats, <i>Mus rattus</i> and <i>Mus
+decumanus</i> in Different Parts of the World." "The Physiological
+Anatomy of the Mouth-parts and Alimentary Canal of the Indian Rat
+Flea, <i>Pulex cheopis</i>," and other papers on the relation of rats to
+plague. The second number, Vol. VII, July, 1907, contains articles
+on "On the Significance of the Locality of the Primary Bubo in
+Animals Infected with Plague in Nature," "Further Observations on
+the Transmission of Plague by Fleas with Special Reference to the
+Fate of Plague Bacillus in the Body of the Rat Flea,"<span class='pagenum'><a name="Page_198" id="Page_198">[Pg 198]</a></span>
+"Experimental Production of Plague Epidemics Among Animals,"
+"Experiments in Plague Houses in Bombay," "On the External Anatomy
+of the Indian Rat Flea and Its Differentiation from Some Other
+Common Fleas," "A Note on Man as a Host of the Indian Rat Flea,"
+and others on the relation of rats to plague. The third number,
+Vol. VII, Dec., 1907, contains articles on "Digest of Recent
+Observations on the Epidemiology of Plague" (Bibliography),
+"Epidemiological Observations in Bombay City," "Epidemiological
+Observations in the Villages of Wadhala, Parel, Worli in the
+Neighborhood of Bombay Village," "General Considerations Regarding
+the Spread of Infection, Infectivity of Houses, etc., in Bombay
+City and Island," "Epidemiological Observations in the villages of
+Dhand and Kasel (Punjab)." The fourth number, Vol. VIII, May, 1908,
+contains articles on "The Part Played by Insects in the
+Epidemiology of Plague" (see also ref. under D.T. Verjbitski),
+"Observations on the Bionomics of Fleas with Special Reference to
+<i>P. cheopis</i>," "The Mechanism by Means of Which the Flea Cleans
+Itself of Plague Bacilli," "On the Seasonal Prevalence of Plague in
+India."</p>
+
+<p>See also under Fleas. </p></div>
+
+
+<p class="center">FLEAS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Baker, C.F.</span> Fleas and Disease. <i>Science</i>, N.S., Vol. 22, No. 559,
+Sept. 15, 1905, p. 340. Discusses the possibility of fleas
+transmitting leprosy.</p>
+
+<p class="hang"><span class="smcap">Doane, R.W.</span> Notes on Fleas, Collected on Rat and Human Hosts in San
+Francisco and Elsewhere. <i>Can. Ento.</i>, 40, 1908, pp. 303&ndash;304. Shows
+that <i>Ceratophyllus fasciatus</i> and <i>Pulex irritans</i> are common on
+both man and rats.</p>
+
+<p class="hang"><span class="smcap">Fox, Carroll.</span> The Flea in Its Relation to Plague, with a Synopsis
+of the Rat Fleas. <i>The Military Surgeon</i>, 24, June, 1909, pp.
+528&ndash;537. Review of the work of the Indian<span class='pagenum'><a name="Page_199" id="Page_199">[Pg 199]</a></span> Plague Commission and
+others. Key for identification of rat fleas.</p>
+
+<p class="hang"><span class="smcap">Galli-Valerio.</span> The Part Played by Fleas of Rats and Mice in the
+Transmission of Bubonic Plague. <i>Jour. Trop. Med.</i>, Feb., 1902.
+Attacks the theory that plague can be conveyed from rats to men by
+fleas because rat fleas do not bite men.</p>
+
+<p class="hang"><span class="smcap">McCoy, G.W.</span> <i>Siphonaptera</i> Observed in the Plague Campaign in
+California with a Note upon Host Transference. <i>Pub. Health Report,
+Pub. Health and Mar. Hospt. Ser.</i>, Vol. XXIV, No. 29, July 16,
+1909. Lists of species from various hosts. Report on experiments in
+transferring rat fleas to squirrels and squirrel fleas to rats.</p>
+
+<p class="hang"><span class="smcap">McCoy, G.W., and Mitzmain, M.B.</span> An Experimental Investigation of
+the Biting of Man by Fleas Taken from Rats and Squirrels. <i>Public
+Health Report</i>, XXIV, No. 8, Feb. 19, 1909, pp. 189&ndash;194. Rat and
+squirrel fleas will bite man.</p>
+
+<p class="hang"><span class="smcap">Mitzmain, M.B.</span> Insect Transmission of Bubonic Plague. A Study of
+the San Francisco Epidemic. <i>Entomological News</i>, Oct., 1908.
+Source and distribution of species of fleas and brief notes on work
+of Indian Plague Commission.</p>
+
+<p class="hang"><span class="smcap">Mitzmain, M.B.</span> How a Hungry Flea Feeds. <i>Entomological News</i>, Dec.,
+1908.</p>
+
+<p class="hang"><span class="smcap">Mitzmain, M.B.</span> Some New Facts on the Bionomics of the California
+Rodent Fleas. <i>Annals Ento. Soc. Amer.</i>, III, pp. 61&ndash;82, 1910.</p>
+
+<p class="hang"><span class="smcap">Shipley, A.E.</span> Rats and Their Animal Parasites. <i>Jour. of Economic
+Biology</i>, Vol. 3, No. 3, Oct. 28, 1908. List of species ecto- and
+endoparasites.</p>
+
+<p>See also reports of Advisory Commission under Plague.</p></div>
+
+
+<p class="center">TYPHOID FEVER</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Anderson, J.F.</span> The Differentiation of Outbreaks of Typhoid Fever
+Due to Water, Milk, Flies and Contact. <i>Amer. Jour. Pub. Health</i>,
+19, pp. 251&ndash;259. Discusses flies and typhoid.</p>
+
+<p><span class='pagenum'><a name="Page_200" id="Page_200">[Pg 200]</a></span></p><p class="hang"><span class="smcap">McCrae, Thomas.</span> Typhoid Fever. <i>Osler's Mod. Med.</i>, Vol. II, p.
+70, 1907. A full discussion of this disease.</p>
+
+<p class="hang"><span class="smcap">Reed, Walter; Vaughan, V.C., and Shakespeare, E.O.</span> Abstract of
+Report on the Origin and Spread of Typhoid Fever in the U.S.
+Military Camps During the Spanish War of 1898. Washington, Govt.
+Printing Office, 1900. Shows among other things that "flies
+undoubtedly served as carriers of infection."</p>
+
+<p class="hang"><span class="smcap">Roseman, M.J., Lumsden, L.L., and Kastle, J.H.</span> Report on Origin and
+Prevalence of Typhoid Fever in D.C. Including reports by Stiles,
+Goldberger and Stimson. <i>Bull. 35 of Hygienic Laboratory of U.S.
+Public Health and Mar. Hospt. Ser.</i>, 1907. (Second report in <i>Bull.
+44</i>, 1907, includes nothing about insects.)</p>
+
+<p class="hang"><span class="smcap">Veeder, M.A.</span> Typhoid Fever from Sources Other Than Water Supply.
+<i>Med. Record</i>, 62, pp. 121&ndash;124, July 26, 1902. Cites several
+instances where flies might act as the carriers of the disease.</p>
+
+<p class="hang"><span class="smcap">Whipple, Geo. C.</span> Typhoid Fever, Its Causation, Transmission and
+Prevention. N.Y., 1908. Considers that house-flies and probably
+fruit-flies carry typhoid bacilli. </p></div>
+
+
+<p class="center">HOUSE-FLIES; ANATOMY, LIFE-HISTORY, HABITS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Felt, E.P.</span> Observations on the House-fly. <i>Jour. Eco. Ento.</i>, III,
+No. 1, Feb., 1910, pp. 24&ndash;26. Shows that it does not breed freely
+in darkness.</p>
+
+<p class="hang"><span class="smcap">Griffith, A.</span> The Life-history of House-flies. <i>Public Health</i>
+(London), 21, No. 3, 1908, pp. 122&ndash;127. Study of life-history.
+Flies require water frequently, eggs hatch in twenty-four hours,
+larval stage four days. Each female may lay four batches of eggs.
+Destroy manure and rubbish.</p>
+
+<p class="hang"><span class="smcap">Hamer, W.H.</span> The Breeding of Flies Summarized. <i>Am. Med.</i>, 3, 1908,
+p. 431. Habits of flies and experiments to show that they may carry
+the germs of various diseases.</p>
+
+<p><span class='pagenum'><a name="Page_201" id="Page_201">[Pg 201]</a></span></p><p class="hang"><span class="smcap">Hepworth, John.</span> On the Structure of the Foot of the Fly. <i>Quar.
+Jour. Micro. Sci.</i>, II, 1859, pp. 158&ndash;563. One plate showing feet
+of different flies. A review of the older theories of how a fly was
+able to walk on smooth surfaces.</p>
+
+<p class="hang"><span class="smcap">Herms, W.B.</span> The Essentials of House-fly Control. <i>Bull. of Berkeley
+Board of Health</i>, Berkeley, Cal., 1909. Recommends removing manure
+as soon as possible and keeping it in tight bins until removed. No
+very satisfactory insecticides have been found for use in treating
+manure piles.</p>
+
+<p class="hang"><span class="smcap">Herms, W.B.</span> The Berkeley House-fly Campaign. <i>Cal. Jour. of
+Technology</i>, Vol. XIV, No. 2, 1909. Discusses the methods that have
+been used in fighting the fly in Berkeley, Cal. Removing manure
+regularly or keeping it in closed bins recommended.</p>
+
+<p class="hang"><span class="smcap">Hewitt, C.G.</span> A Preliminary Account of the Life-history of the
+Common House-fly. <i>Mem. and Proc. Manchester Lit. Phil. Soc.</i>,
+1906, Vol. 51, pp. 1&ndash;4.</p>
+
+<p class="hang"><span class="smcap">Hewitt, C.G.</span> On the Bionomics of Certain Calyptrate Mucid&aelig; and
+Their Economic Significance with Especial Reference to Flies
+Inhabiting Houses. <i>Jour. Econ. Biol.</i>, 1907, Vol. II, pp. 79&ndash;88.
+Character and importance of group and notes on many species.</p>
+
+<p class="hang"><span class="smcap">Hewitt, C.G.</span> Structure, Development and Bionomics of the House-fly,
+<i>Muca domestica</i>. Part I, <i>Quar. Jour. Micro. Sci.</i>, 1907, p. 395,
+on anatomy, external and internal, and bibliography. Part II, same;
+1908, p. 495. Breeding-habits, development and anatomy of larv&aelig;,
+bibliography. Part III, same; 1909, pp. 347&ndash;414. The bionomics,
+allies, parasites, and the relations to human disease. The best
+article on the house-fly.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Further Notes on the House-fly. <i>Bull. 10, U.S. Dept.,
+Agric. Div. of Ento.</i>, p. 63, 1898. Experiments to kill larv&aelig; in
+manure.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> House-flies. <i>U.S. Dept. of Agric., Bureau of<span class='pagenum'><a name="Page_202" id="Page_202">[Pg 202]</a></span> Ento.,
+Circular No. 71</i>, revised ed., 1906. Methods of control of
+house-fly and related species.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O., and Marlatt, C.L.</span> <i>Bull. 4, U.S. Dept. Agric., Div.
+of Ento.</i>, pp. 43&ndash;47, 1896. General account with methods of
+controlling.</p>
+
+<p class="hang"><span class="smcap">Jepson, F.P.</span> The Breeding of the Common House-fly During the Winter
+Months. <i>Jour. Econ. Biol.</i>, 4, 1909, pp. 78&ndash;82. Records of certain
+experiments which show that the flies will breed in winter under
+favorable conditions.</p>
+
+<p class="hang"><span class="smcap">Newstead, R.</span> Preliminary Report on the Habits, Life-cycle and
+Breeding-places of the Common House-fly as Observed in the City of
+Liverpool, with Suggestions as to the Best Means of Checking Its
+Increase. Liverpool, Oct. 3, 1907.</p>
+
+<p class="hang"><span class="smcap">Newstead, R.</span> On the Habits, Life-cycle and Breeding-places of the
+Common House-fly. <i>Ann. Trap. Med. Para.</i>, Vol. I, No. 4, Feb. 29,
+1908, pp. 507&ndash;520. Final report on this subject. Sums up notes on
+life-history, habits, breeding-places, etc. Important article.</p>
+
+<p class="hang"><span class="smcap">Packard, A.S.</span> On the Transformation of the Common House-fly with
+Notes on Allied Forms. <i>Proc. Boston Soc. Nat. Hist.</i>, Vol. XVI,
+1874, pp. 136&ndash;140. Life-history and anatomy.</p>
+
+<p class="hang"><span class="smcap">Wilcox, E.V.</span> Fighting the House-fly. <i>Country Life in America</i>,
+May, 1908. Methods of controlling this pest. </p></div>
+
+
+<p class="center">HOUSE-FLIES AND TYPHOID</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Austen, E.E.</span> The House-fly and Certain Allied Species as
+Disseminators of Enteric Fever Among the Troops in the Field.
+<i>Jour. Roy. Army Med. Corps</i>, June, 1904. Suggests that it may
+carry enteric fever and other diseases; method of control.</p>
+
+<p class="hang"><span class="smcap">Felt, E.P.</span> The Typhoid or House-fly and Disease. In 24th <i>Rept. of
+State Ento</i>. in <i>N.Y. State Museum Bull.</i>, No. 455, 1909. A general
+discussion with complete bibliography.</p>
+
+<p><span class='pagenum'><a name="Page_203" id="Page_203">[Pg 203]</a></span></p><p class="hang"><span class="smcap">Firth, R.H., and Horrocks, W.H.</span> An Inquiry Into the Influence of
+Soil, Fabrics, and Flies in the Dissemination of Enteric Infection.
+<i>Brit. Med. Jour.</i>, Vol. II, 1902, pp. 936&ndash;942. House-flies carry
+enteric bacilli. They may pass through digestive tract and remain
+virulent.</p>
+
+<p class="hang"><span class="smcap">Hamilton, Alice.</span> The Fly as a Carrier of Typhoid. <i>Jour. Amer. Med.
+Assn.</i>, 40, 1903, pp. 576&ndash;83. A study of a typhoid outbreak in
+Chicago gives good evidence that the flies were important factors
+in the spread of the disease.</p>
+
+<p class="hang"><span class="smcap">Hewitt, C.G.</span> The Biology of House-flies in Relation to Public
+Health. <i>Royal Inst. Pub. Health Jour.</i>, Oct., 1908.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> A contribution to the Study of the Insect Fauna of
+Human Excrement. <i>Proc. Wash. Acad. Sci.</i>, 2, 1900, pp. 541&ndash;600.
+Special reference to the house-fly and typhoid fever.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Flies and Typhoid. <i>Pop. Sci. Mo.</i>, Jan., 1901, pp.
+249&ndash;256. A popular account of several species of flies that may be
+concerned in carrying typhoid.</p>
+
+<p class="hang"><span class="smcap">Klein, E.</span> Flies as Carriers of <i>B. typhus</i>. <i>Brit. Med. Jour.</i>,
+Oct. 17, 1908, pp. 1150&ndash;51. In cultures made from flies he found
+great numbers of <i>B. coli communis</i> and <i>B. typhosus</i>, showing that
+flies may carry these germs.</p>
+
+<p class="hang"><span class="smcap">Martin, A.</span> Flies in Relation to Typhoid and Summer Diarrhea.
+<i>Public Health</i>, 15, 1903, pp. 652&ndash;653. Believes that the house-fly
+is largely responsible for these diseases.</p>
+
+<p class="hang"><span class="smcap">Reed, Walter.</span> <i>War Dept. An. Rept.</i>, 1899, pp. 627&ndash;633. Flies the
+cause of a typhoid outbreak in army in 1899. </p></div>
+
+
+<p class="center">HOUSE-FLY AND VARIOUS DISEASES</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Buchanan, R.A., Glasg, F.F., and M.B.</span> The Carriage of Infection by
+Flies. <i>Lancet</i>, 173, 1907, pp. 216&ndash;218. Flies carry various germs
+on their feet and distribute them where they walk. Must protect
+food from contamination.</p>
+
+<p><span class='pagenum'><a name="Page_204" id="Page_204">[Pg 204]</a></span></p><p class="hang"><span class="smcap">Brewster, E.T.</span> The Fly. The Disease of the House. <i>McClure's
+Magazine</i>, XXXIII; No. 5, Sept., 1909, pp. 564&ndash;568. Proposes to
+make use of tropisms for ridding the houses of flies.</p>
+
+<p class="hang"><span class="smcap">Castellani, Aldo.</span> Experimental Investigation on <i>Framb&#339;sia
+tropica</i> (Yaws). <i>Jour. of Hyg.</i>, Vol. VII, 1907, pp. 558&ndash;599. On
+pages 566&ndash;568 he discusses the part played by insects in
+transmitting the disease. Gives detail of experiments conducted and
+concludes that under certain conditions yaws may be conveyed by
+flies and possibly other insects.</p>
+
+<p class="hang"><span class="smcap">Cobb, J.O.</span> Is the Common House-fly a Factor in the Spread of
+Tuberculosis? <i>Amer. Med.</i>, 9, 1905, pp. 475&ndash;477. Believes that the
+bacilli may enter the system through the digestive tract and that
+flies carry them to our food.</p>
+
+<p class="hang"><span class="smcap">Dickenson, G.K.</span> The House-fly and Its Connection with Disease
+Dissemination. <i>Med. Record</i>, 71, 1907, pp. 134&ndash;139. Summary;
+bibliography.</p>
+
+<p class="hang"><span class="smcap">Esten, W.M., and Mason, C.J.</span> Sources of Bacteria in Milk. Starr's
+<i>Agric. Ex. Stn., Conn. Bull.</i>, 51, 1908. Shows how flies may carry
+bacteria to milk. Table showing number of bacteria on flies from
+various sources.</p>
+
+<p class="hang"><span class="smcap">Felt, E.P.</span> The Economic Status of the House-fly. <i>Jour. Eco.
+Ento.</i>, Vol. 2, No. 1, Feb., 1909, pp. 39&ndash;45. A summary of the
+charges, possibilities, proofs, etc. Discussion.</p>
+
+<p class="hang"><span class="smcap">Gudger, E.W.</span> Early Note on Flies as Transmitters of Disease.
+<i>Science</i>, N.S. Vol. 31, Jan. 7, 1910, pp. 31&ndash;32.</p>
+
+<p class="hang"><span class="smcap">Hamer, W.H.</span> Nuisance from Flies. <i>London County Council Rept.</i> No.
+1,138, pp. 1&ndash;10, and No. 1,207, pp. 1&ndash;6, 1908. Observations on
+various flies and their relation to diseases.</p>
+
+<p class="hang"><span class="smcap">Hayward, E.H.</span> The Fly as a Carrier of Tuberculosis Infection. <i>N.Y.
+Med. Jour.</i>, 80, 1904, pp. 643&ndash;644. Tubercular bacilli pass through
+the digestive tract of flies and remain virulent.</p>
+
+<p><span class='pagenum'><a name="Page_205" id="Page_205">[Pg 205]</a></span></p><p class="hang"><span class="smcap">Howard, L.O.</span> The Carriage of Disease by Flies. <i>Bull. 30</i>, N.S.,
+pp. 39&ndash;45, <i>U.S. Dept. Agric, Div. of Ento.</i>, 1901. Discussion of
+flies as carriers of disease.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> House-flies. <i>U.S. Dept. of Agric., Bureau of Ento.</i>,
+Cir. No. 71, revised ed., Sept. 21, 1906. Notes on the various
+species visiting houses; habits; methods of control; regulations
+for controlling flies in cities.</p>
+
+<p class="hang"><span class="smcap">Hutchinson, Woods.</span> The Story of the Fly That Does Not Wipe Its
+Feet. <i>Sat. Evening Post</i>, March 7, 1908.</p>
+
+<p class="hang"><span class="smcap">Jackson, Daniel D.</span> Conveyance of Disease by Flies Summarized.
+<i>Bost. Med. &amp; Surg. Jour.</i>, 1908, p. 451. Disease and flies prevail
+at same time; records over 1,000,000 bacteria to each fly caught on
+swill-barrels.</p>
+
+<p class="hang"><span class="smcap">Jackson, Daniel B.</span> Pollution of New York Harbor as a Menace to
+Health by the Dissemination of Intestinal Diseases Through the
+Agency of the Common House-fly. Account of experiments and
+deductions. Pamphlet issued July, 1908, by Merchants' Assn. of New
+York.</p>
+
+<p class="hang"><span class="smcap">Leidy, Joseph.</span> Flies as a Means of Communicating Contagious
+Diseases. <i>Proc. Acad. Nat. Sci. Phil.</i>, 23, 1871, p. 297. Believes
+that flies may carry disease; refers to flies in connection with
+gangrene and wounds.</p>
+
+<p class="hang"><span class="smcap">Lord, F.T.</span> Flies and Tuberculosis. <i>Bost. Med. &amp; Surg. Jour.</i>,
+1904, pp. 651&ndash;654. Fly-specks may contain virulent tubercular
+bacilli for at least fifteen days.</p>
+
+<p class="hang"><span class="smcap">Mays, Thos. J.</span> The Fly and Tuberculosis. <i>N.Y. Med. Jour. &amp; Phila.
+Med. Jour.</i>, 82, 1905, pp. 437&ndash;438. Believes that J.O. Cobb's data
+as given in <i>Amer. Med. Jour.</i> is not at all conclusive.</p>
+
+<p class="hang"><span class="smcap">Nash, J.C.T.</span> A Note on the Bacterial Contamination of Milk as
+Illustrating the Connection Between Flies and Epidemic Diarrhea.
+<i>Lancet</i>, II, 1908, pp. 1668&ndash;69. Experiments show that milk left
+exposed to flies soon contains many more germs than that protected
+from them.</p>
+
+<p><span class='pagenum'><a name="Page_206" id="Page_206">[Pg 206]</a></span></p><p class="hang"><span class="smcap">Nash, J.C.T.</span> The &AElig;tiology of Summer Diarrhea. <i>Lancet</i>, 164, 1903,
+p. 330. Believes house-fly carries this disease because the two
+appear and disappear together.</p>
+
+<p class="hang"><span class="smcap">Robertson, A.</span> Flies as Carriers of Contagion in Yaws. <i>Jour. Trop.
+Med. &amp; Hyg.</i>, 11, 1908, No. 14, p. 213. As a result of examinations
+the author concludes that the house-fly is capable of carrying the
+virus of yaws.</p>
+
+<p class="hang"><span class="smcap">Sandilands, J.E.</span> Epidemic Diarrhea and the Bacterial Control of
+Food. <i>Jour. Hyg.</i>, 6, 1906, pp. 77&ndash;92. Believes that house-flies
+convey these diseases from the excrement of infected infants.</p>
+
+<p class="hang"><span class="smcap">Sibthorpe, E.H.</span> Cholera and Flies. <i>Brit. Med. Jour.</i>, Sept., 1896,
+p. 700. Flies considered scavengers, think they thus help abate the
+disease.</p>
+
+<p class="hang"><span class="smcap">Smith, T.</span> The House-fly as an Agent in Dissemination of Infectious
+Diseases. <i>Amer. Jour. Pub. Hyg.</i>, Aug., 1908, pp. 312&ndash;317. Points
+out that flies on account of their habits, are dangerous sources of
+contamination.</p>
+
+<p class="hang"><span class="smcap">Smith, Theobald.</span> The House-fly at the Bar. Merchants' Assn., New
+York, 1909, pp. 1&ndash;48. Letters from various authorities giving their
+opinion; quotations from various authors. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Veeder, M.A.</span> Flies as Spreaders of Sickness in Camps. <i>Med.
+Record</i>, 54, 1898, pp. 429&ndash;430. Flies feed on typhoid excreta and
+pass to food. Cultures made from fly tracks and excreta show many
+bacteria present.</p>
+
+<p class="hang"><span class="smcap">Veeder, M.A.</span> The Relative Importance of Flies and Water Supply in
+Spreading Disease. <i>Med. Record</i>, 55, 1899, pp. 10&ndash;12. Reasons for
+believing that flies spread disease in many instances. Burial of
+infected typhoid material no protection but a menace.</p>
+
+<p class="hang">Dangers from Flies. E.P.W. <i>Nature</i>, Vol. 29, pp. 482&ndash;483. Review
+of an article by Dr. B. Grassi in regard to flies and various
+diseases. Opthalmia is discussed. Flies may ingest<span class='pagenum'><a name="Page_207" id="Page_207">[Pg 207]</a></span> and pass
+unharmed eggs of various human parasites including tapeworm. </p></div>
+
+
+<p class="center">HUMAN MYIASIS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Allen, Chas. H.</span> Demonstration of Locomotion in the Larv&aelig; of the
+&#338;strid&aelig;. <i>Proc. Amer. Assn. Adv. Set.</i>, Vol. 24, 1875, pp.
+230&ndash;236. Larv&aelig; taken from flesh of child, one had moved thirty-six
+inches and one six inches.</p>
+
+<p class="hang"><span class="smcap">French, G.H.</span> A Parasite the Supposed Cause of Some Cases of
+Epilepsy. <i>Canad. Ento.</i>, 32, 1900, pp. 263&ndash;264. Larv&aelig; of
+<i>Gastrophilus</i> or <i>Dermatobia</i> in the alimentary canal supposed to
+have caused spasms in young boy.</p>
+
+<p class="hang"><span class="smcap">Gilbert, N.C.</span> Infection of Man by Dipterous Larv&aelig; with Report of
+Four Cases. <i>Archives of Internal Med.</i>, Oct., 1908. Historical;
+various kinds sometimes found in man; good summary of subject.
+Bibliography.</p>
+
+<p class="hang"><span class="smcap">Harrison, J.H.H.</span> A Case of Myiasis. <i>Jour. Trop. Med. &amp; Hyg.</i>, XI,
+Oct. 15, 1908, p. 305. Over 300 larv&aelig; of <i>Lucilia macellaria</i>
+removed from face of negro woman.</p>
+
+<p class="hang"><span class="smcap">Humbert, Fred.</span> <i>Lucilia macellaria</i> Infesting Man. <i>Proc. U.S. Nat.
+Museum</i>, 6, 1883, pp. 103&ndash;104. Records several cases in which the
+screw-worm infested patients.</p>
+
+<p class="hang"><span class="smcap">Jenyus, Leonard.</span> <i>Trans. Ento. Soc.</i>, London, Vol. II, 1839, pp.
+152&ndash;159. Notice of a case in which the larv&aelig; of a dipterous insect,
+supposed to be <i>Anthomyia canicularis</i>, Meig., were expelled in
+large quantities from the human intestines.</p>
+
+<p class="hang"><span class="smcap">Kane, E.R.</span> A Grub Supposed to Have Traveled in the Human Body.
+<i>Insect Life</i>, II, 1890, pp. 238&ndash;239. Larva of bot-fly taken from
+face of boy. It had been traveling under the skin for about five
+months.</p>
+
+<p class="hang"><span class="smcap">McCampbell, E.F., and Cooper, H.J.</span> <i>Myiasis intestinalis</i> Due to
+Infection with Three Species of Dipterous Larv&aelig;. <i>Jour. Amer. Med.
+Assn.</i>, 53, Oct. 9, 1909, pp. 1160&ndash;62. General<span class='pagenum'><a name="Page_208" id="Page_208">[Pg 208]</a></span> notes on this
+subject and a report on a case in which larv&aelig; of three different
+species of flies were obtained from one patient.</p>
+
+<p class="hang"><span class="smcap">Meinert, Fr.</span> <i>Lucilia nobilis</i> Parasitic on Man. <i>Insect Life</i>, II,
+1892, pp. 36&ndash;37. Two larv&aelig; from the ear of a man proved to be the
+above species.</p>
+
+<p class="hang"><span class="smcap">Murtfeledt, M.E.</span> Hominivorous Habits of the Screw-worm in St.
+Louis. <i>Insect Life</i>, IV, 1891, p. 200. Many larv&aelig; of this species
+removed from the nasal passages of a patient.</p>
+
+<p class="hang"><span class="smcap">Nelson, J.B.</span> Insects in the Human Ear. <i>Insect Life</i>, VI, 1893, p.
+56. Two cases in which blow-fly larv&aelig; are reported as coming from
+the human ear.</p>
+
+<p class="hang"><span class="smcap">Riley, W.A.</span> A Case of Pseudoparasitism by Dipterous Larv&aelig;. <i>Canad.
+Ento.</i>, 38, 1906, p. 413. Several larv&aelig;, species undetermined,
+removed from back of patient.</p>
+
+<p class="hang"><span class="smcap">Say, Thomas.</span> On a South American Species of &#338;strus Which
+Inhabits the Human Body. <i>Tr. Phil. Acad. Nat. Sci.</i>, Vol. 2, 1822,
+pp. 353&ndash;360. Extended notes on various dipterous larv&aelig; infesting
+man.</p>
+
+<p class="hang"><span class="smcap">Snow, F.H.</span> Hominivorous Habits of <i>Lucilia macellaria</i> "The
+Screw-worm." <i>Psyche</i>, 4, 1883, pp. 27&ndash;30. Cites observations made
+by himself and others.</p>
+
+<p class="hang"><span class="smcap">Williston, S.W.</span> The Screw-worm Fly <i>Compsomyia macellaria</i>.
+<i>Psyche</i>, 4, 1883, pp. 112&ndash;114. Notes on this species with a
+translation of a Spanish article by Anibalzaga in which instances
+of this fly infesting human beings are recorded.</p>
+
+<p class="hang"><span class="smcap">Yount, C.E., and Sudler, M.T.</span> Human Myiasis from the Screw-worm
+Fly. <i>Jour. Amer. Med. Assn.</i>, Vol. 49, No. 23, 1907, p. 1912.
+Several cases giving reference to literature, symptomatology,
+diagnosis. </p></div>
+
+
+<p class="center">STOMOXYS AND OTHER FLIES</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Austen, E.E.</span> Blood-sucking and Other Flies Known or Likely to Be
+Concerned in the Spread of Disease. In Albutt's<span class='pagenum'><a name="Page_209" id="Page_209">[Pg 209]</a></span> and Rolleston's
+<i>System of Med.</i>, 2, 1907, pp. 169&ndash;186. A descriptive list of these
+flies. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Austen, E.E.</span> Illustrations of African Blood-sucking Flies Other
+Than Mosquitoes and Tsetse-flies. London, 1909.</p>
+
+<p class="hang"><span class="smcap">Newstead, R.</span> On the Life-history of <i>Stomoxys calcitrans</i>. <i>Jour.
+Econom. Biology</i>, Vol. I, 1906, pp. 157&ndash;166. Describes habits and
+life-history of larv&aelig; and adults. Important article.</p>
+
+<p class="hang"><span class="smcap">Stephens, J.W.W., and Newstead, R.</span> The Anatomy of the Proboscis of
+Biting Flies. Part II, <i>Stomoxys</i>. <i>Ann. of Trop. Med. &amp; Parasit.</i>,
+Vol. I, No. 2, June 15, 1907, pp. 171&ndash;182. Good anatomical paper.
+Part I (<i>Glossina</i>) was published in mem. XVIII, 1906, Liverpool
+School Trop. Med.</p>
+
+<p class="hang"><span class="smcap">Tullock, F.</span> Internal Anatomy of <i>Stomoxys</i>. <i>Proc. Roy. Soc.</i>,
+London, 77, Series B, 1906, pp. 523&ndash;531. Descriptions and drawings
+comparing with <i>Glossina</i>. </p></div>
+
+
+<p class="center">TSETSE-FLIES</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Austen, E.E.</span> A Monograph of the Tsetse-flies. Published by order of
+the Trustees of the British Museum, 1903.</p>
+
+<p class="hang"><span class="smcap">Manson, P.</span> Tsetse-flies. In <i>Trop. Diseases</i>, p. 174. Description
+of genus; table of species; distribution; reproduction, habits.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> Report of Anatomy of the Tsetse-fly (<i>Glossina
+palpalis</i>). <i>Proc. Roy. Soc.</i>, London, 76, Series B, 1905, pp.
+531&ndash;547. Good account of internal anatomy of this fly, important
+because of its relation to trypanosomiasis.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> The Breeding-habits of the Tsetse-fly. <i>Nature</i>, Oct.
+25, 1906, p. 636.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A., Gray, A.C.H., and Tullock, F.M.G.</span> (Sleeping Sickness
+Com.) <i>Glossina palpalis</i> in Its Relation to <i>Trypanosoma
+gambiense</i> and Other Trypanosomes (Preliminary Report). <i>Proc. Roy.
+Soc.</i>, Vol. 78, 1906, pp. 242&ndash;258. Report on certain experiments in
+feeding these flies on infected<span class='pagenum'><a name="Page_210" id="Page_210">[Pg 210]</a></span> animals and in allowing supposedly
+infected flies to feed on various animals.</p>
+
+<p class="hang"><span class="smcap">Novy, F.G.</span> The Trypanosomes of Tsetse-flies. <i>Jour. Infec. Dis.</i>,
+III, 1906, pp. 394&ndash;411. Notes on the various species. </p></div>
+
+
+<p class="center">TRYPANOSOMES AND TRYPANOSOMIASIS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Bruce, David.</span> Trypanosomiasis. <i>Osler's Mod. Med.</i>, Vol. I, 1907,
+p. 460. A discussion of <i>Trypanosoma lewisi</i>, <i>evansi</i>, <i>brucei</i>,
+<i>gambiensi</i>, and the diseases caused by them.</p>
+
+<p class="hang"><span class="smcap">Dutton, J.E., Todd, J.L., and Harrington, J.W.B.</span> Trypanosome
+Transmission Experiments. <i>Am. Trop. Med. &amp; Parasit.</i>, Vol. I, No.
+2, June 15, 1907, pp. 201&ndash;229. Sections on attempts to transmit
+trypanosomes by tsetse-flies; by other blood-sucking Arthropods,
+etc., conclude that trypanosomes may be mechanically transmitted by
+the bite of blood-sucking Arthropods.</p>
+
+<p class="hang"><span class="smcap">Hooker, W.A.</span> Descriptions of Certain Trypanosomes, and Review of
+the Present Knowledge of the R&ocirc;le of Ticks in the Dissemination of
+Disease. <i>Jour. Econ. Ento.</i>, Vol. I, No. 1, 1908, pp. 65&ndash;76. Good
+review, tables and literature.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> Investigations on the Development of Trypanosomes in
+Tsetse-flies and Other <i>Diptera</i>. <i>Quart. Jour. Micro. Sci.</i>, 1908,
+pp. 159&ndash;260.</p>
+
+<p class="hang"><span class="smcap">Musgrove, W.E., and Clegg, M.T.</span> Trypanosomes and Trypanosomiasis,
+with Special Reference to Surra in the Philippine Islands.
+<i>Biological Lab., Bull. No. 5</i>, Manila, 1903. Discuss flies, fleas,
+mosquitoes, lice and ticks as possible disseminators of the
+disease.</p>
+
+<p class="hang"><span class="smcap">Novy, T.G., McNeal, M.J., and Torry, H.M.</span> The Trypanosomes of
+Mosquitoes and Other Insects. <i>Jour. Infec. Diseases</i>, IV, 1907,
+pp. 223&ndash;276. These parasites are often found in mosquitoes and
+other insects. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Nuttall, G.H.F.</span> The Transmission of <i>Trypanosoma lewisi</i><span class='pagenum'><a name="Page_211" id="Page_211">[Pg 211]</a></span> by Fleas
+and Lice. <i>Parasitology</i>, Vol. I, No. 4, Dec., 1908, pp. 296&ndash;301.
+This rat trypanosome is transmitted by fleas and lice.</p>
+
+<p class="hang"><span class="smcap">Old, J.E.S.</span> Contribution to the Study of Trypanosomiasis and to the
+Geographical Distribution of Some of the Blood-sucking Insects,
+etc. <i>Jour. Trop. Med. &amp; Hyg.</i>, 12, Jan. 15, 1909, pp. 15&ndash;22. Notes
+on blood-sucking <i>Diptera</i> and ticks.</p>
+
+<p class="hang"><span class="smcap">Rogers, Leonard.</span> The Transmission of the <i>Trypanosoma evansi</i> by
+House-flies and Other Experiments Pointing to the Probable Identity
+of Surra of India and Nagana or Tsetse-fly Disease of Africa.
+<i>Proc. Roy. Soc.</i>, Vol. LXVIII, 1901, pp. 163&ndash;170.</p>
+
+<p class="hang"><span class="smcap">Thimm, C.A.</span> Bibliography of Trypanosomiasis; embracing original
+papers published prior to April 1909, and references to works and
+papers on tsetse-flies. London, 1909.</p>
+
+<p class="hang"><span class="smcap">Todd, J.L.</span> A Note on Recent Trypanosome Transmission Experiments.
+<i>Jour. Trop. Med. &amp; Hyg.</i>, 12, Sept., 1909, p. 260. Show that they
+develop in <i>G. palpalis</i> when taken from their mammal host at the
+proper stage of development.</p>
+
+<p class="hang"><span class="smcap">Woodcock, H.M.</span> The H&aelig;moflagellates: a Review of Present Knowledge
+Relating to the Trypanosomes and Allied Forms. <i>Quar. Jour. Micro.
+Sci.</i>, Vol. 50, 1906, pp. 151&ndash;331. Characteristics; mode of
+infection; effects on host; biological considerations; life-cycle,
+etc. <i>Spirochaet&aelig;</i>; bibliography. Important article.</p>
+
+<p class="hang">Trypanosomiasis and Sleeping Sickness. <i>Jour. Trop. Med. &amp; Hyg.</i>,
+II, pp. 146&ndash;147, 162, 179&ndash;180, 196. List of recent literature. </p></div>
+
+
+<p class="center">SLEEPING SICKNESS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Bagshawe, A.G.</span> Recent Advances in Our Knowledge of Sleeping
+Sickness. <i>Lancet</i>, II, 1909, pp. 1193&ndash;97. A summing up of the
+important discoveries of the preceding year.</p>
+
+<p class="hang"><span class="smcap">Hearsey, H.</span> Sleeping Sickness. <i>Jour. Trop. Met. &amp; Hyg.</i>, 12, Sept.
+1, 1909, pp. 263&ndash;264. Report on work accomplished<span class='pagenum'><a name="Page_212" id="Page_212">[Pg 212]</a></span> particularly in
+relation to the distribution of <i>Glossina</i> and other biting flies.</p>
+
+<p class="hang"><span class="smcap">Jarvis, C.</span> Sleeping Sickness. <i>Internat. Clinics</i>, Vol. II, 1904,
+pp. 37&ndash;44. Shows the relation of the tsetse-fly to this disease.</p>
+
+<p class="hang"><span class="smcap">Lankester, E.R.</span> The Sleeping Sickness. <i>Quar. Review</i>, July, 1904,
+p. 113. Discovery and early history; the fly, the parasite; other
+related parasites. Relation of parasites to their hosts.</p>
+
+<p class="hang"><span class="smcap">Minchin, E.A.</span> The &AElig;tiology of Sleeping Sickness. <i>Nature</i>, Nov. 15,
+1906, pp. 56&ndash;59.</p>
+
+<p class="hang"><span class="smcap">Wollaston, A.F.R.</span> Amid the Snow Peaks of the Equator: a
+Naturalist's Explorations Around Ruwenzori, with an <i>Account of the
+Terrible Scourge of Sleeping Sickness</i>. <i>Nat. Geo. Mag.</i>, XX, No.
+3, Mar., 1909. Abstracted from "From Ruwenzori to the Congo" by
+above author.</p>
+
+<p class="hang">Reports of the Sleeping Sickness Com. of the Royal Society, I to
+IX, 1903 to 1908. Studies and experiments with the trypanosomes and
+flies concerned in this disease. Later articles by this commission
+are to be found in the <i>Pro. Royal Soc.</i>, Series B, LXXXI and
+LXXXII.</p>
+
+<p class="hang">Sleeping Sickness Bureau Bulletins, 1 to 14, 1908&ndash;1910. Records of
+studies and experiments with trypanosomes and tsetse-flies, etc.</p>
+
+<p class="hang">Transmission of Sleeping Sickness. Editorial in <i>Jour. Amer. Med.
+Assn.</i>, 53, Oct. 2, 1909, pp. 1104&ndash;05. Reviews recent experiments
+and studies. </p></div>
+
+
+<p class="center">ROCKY MOUNTAIN FEVER AND TICKS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Anderson, J.F.</span> Spotted Fever (Tick Fever) of the Rocky Mountains.
+<i>Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull. 14</i>, 1903.
+Distribution, &aelig;tiology, etc. Believes that ticks are responsible
+for the transmission of the disease.</p>
+
+<p class="hang"><span class="smcap">Cooley, R.A.</span> Preliminary Report on the Wood-tick. <i>Bull. 75, Mont.
+Ex. Stn.</i>, 1908. Sums up Ricketts' finding; notes on life-history
+in laboratory and field.</p>
+
+<p><span class='pagenum'><a name="Page_213" id="Page_213">[Pg 213]</a></span></p><p class="hang"><span class="smcap">King, W.W.</span> Experimental Transmission of Rocky Mountain Fever by
+Means of the Tick. Preliminary note. <i>Pub. Health and Mar. Hospt.
+Ser.</i>, 21, July 27, 1906, pp. 863&ndash;864. Conveyed this fever from one
+guinea-pig to another by means of the tick.</p>
+
+<p class="hang"><span class="smcap">Ricketts, H.T.</span> The Transmission of Rocky Mountain Fever by the Bite
+of the Wood-tick (<i>Dermacentor occidentalis</i>). <i>Jour. Amer. Med.
+Assn.</i>, Vol. 47, Aug., 1906, p. 358. Guinea-pig successfully
+inoculated by means of tick.</p>
+
+<p class="hang"><span class="smcap">Ricketts, H.T.</span> The R&ocirc;le of the Wood-tick (<i>Dermacentor
+occidentalis</i>) in Rocky Mountain Spotted Fever. <i>Jour. Amer. Med.
+Assn.</i>, Vol. 49, July 6, 1907, pp. 24&ndash;27. Notes on experiments
+conducted and studies made. Takes position that these experiments
+connect the tick with the transmission of the fever.</p>
+
+<p class="hang"><span class="smcap">Robinson, A.A.</span> Rocky Mountain Spotted Fever. <i>Med. Rec.</i>, Nov. 28,
+1908. Occurrence and distribution of the disease; review of the
+various theories in regard to its transmission. P.E. Jones of Salt
+Lake believes it is transmitted by mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Stiles, C.W.</span> A Zo&ouml;logical Investigation Into the Cause,
+Transmission and Source of Rocky Mountain Spotted Fever. <i>Hyg. Lab.
+Pub. Health and Mar. Hospt. Ser., Bull. 20</i>, 1905. Does not find
+the parasite that had been recorded by others, and finds no
+evidence to indicate that the ticks transmit the disease.</p>
+
+<p class="hang"><span class="smcap">Wilson, L.B., and Channing, W.M.</span> Studies in <i>Pyroplasmosis hominis</i>
+(Spotted Fever or Tick Fever of the Rocky Mountains). <i>Jour. Infec.
+Diseases</i>, 1, 1904, pp. 31&ndash;57. Evidence that the disease is
+transmitted solely by means of the ticks. </p></div>
+
+
+<p class="center">TICKS AND VARIOUS DISEASES</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Banks, Nathan.</span> Tick-borne Diseases and Their Origin. <i>Jour. Eco.
+Ento.</i>, Vol. I, No. 3, 1908, pp. 213&ndash;215. Shows how<span class='pagenum'><a name="Page_214" id="Page_214">[Pg 214]</a></span> ticks may
+become important disease-carriers by changing their hosts as the
+normal host is exterminated, or for other reasons.</p>
+
+<p class="hang"><span class="smcap">Banks, Nathan.</span> A Revision of the Ixodoidea or Ticks of the United
+States. <i>Tech. Series No. 15, Bull. of Bureau of Ento., U.S. Dept.
+Agric.</i>, 1908. Structure, life-history, classification, catalogue,
+bibliography.</p>
+
+<p class="hang"><span class="smcap">Barber, C.A.</span> The Tick Pest in the Tropics. <i>Nature</i>, 52, 1895, pp.
+197&ndash;200. Direct and indirect effects of ticks on their hosts.</p>
+
+<p class="hang"><span class="smcap">Christy, C.</span> <i>Ornithodoros moubata</i> and Tick Fever in Man. <i>Brit.
+Med. Jour.</i>, Vol. II, 1903, p. 652. Relation of the tick to
+<i>Filaria perstans</i>.</p>
+
+<p class="hang"><span class="smcap">Dutton, J.E., and Todd, J.L.</span> The Nature of Human Tick Fever in the
+Eastern Part of the Congo Free State with Notes on the Distribution
+and Bionomics of the Tick. Liverpool School of Tropical Medicine.
+<i>Memoir</i>, 17, Nov., 1905, pp. 1&ndash;18.</p>
+
+<p class="hang"><span class="smcap">Hooker, W.A.</span> A Review of the Present Knowledge of the R&ocirc;le of Ticks
+in the Transmission of Disease. <i>Jour. Eco. Ento.</i>, Vol. I, No. 1,
+1908, p. 65. Review of the subject; table showing zo&ouml;logical
+position of parasites transmitted by ticks. Table showing
+zo&ouml;logical position of ticks.</p>
+
+<p class="hang"><span class="smcap">Hooker, W.A.</span> Life-history, Habits and Methods of Study of the
+Ixodoidea. <i>Jour. Eco. Ento.</i>, Vol. 1, No. 1, 1908, p. 34. Notes on
+several species, especially <i>M. annulatus</i>. Host relationship;
+adaptations as factors in host relationship; mating; geographical
+distribution; methods of breeding, etc.</p>
+
+<p class="hang"><span class="smcap">Hooker, W.A.</span> Some Host Relations of Ticks. <i>Jour. Eco. Ento.</i>, Vol.
+2, No. 3, 1909, p. 251. Notes on ticks found on various hosts.</p>
+
+<p class="hang"><span class="smcap">Hunter, W.D., and Hooker, W.A.</span> Information Concerning the North
+American Fever Tick with Notes on Other Species. <i>Bull. 72, Bureau
+of Ento.</i>, 1907. Life-history, host relation, etc., of fever tick;
+classification and notes on other species; bibliography divided
+into sections.</p>
+
+<p><span class='pagenum'><a name="Page_215" id="Page_215">[Pg 215]</a></span></p><p class="hang"><span class="smcap">Lounsbury, C.P.</span> Habits and Peculiarities of Some South African
+Ticks. <i>Rept. of the Brit. Assn. for the Advancement of Sci.</i>, 1905
+(South Africa), pp. 282&ndash;291.</p>
+
+<p class="hang"><span class="smcap">McCrae, Thomas.</span> Relapsing Fever. <i>Osler's Mod. Med.</i>, Vol. II, p.
+245, 1907. &AElig;tiology, symptoms, treatment, etc. (Apparently
+communicated by blood-sucking insects.)</p>
+
+<p class="hang"><span class="smcap">Newstead, R.</span> On the Pathogenic Ticks Concerned in the Distribution
+of Diseases in Man. <i>Brit. Med. Jour.</i>, II, 1905, pp. 1695&ndash;97.
+Classification and habits, particularly of <i>Ornithodoros moubata</i>.</p>
+
+<p class="hang"><span class="smcap">Nuttall, G.H.F.</span> The Ixodoidea or Ticks. <i>Jour. of Roy. Inst. of
+Pub. Health</i>, 1908. List of disease-bearing ticks. Position of
+ticks, classification. Biology. Preventive measures.</p>
+
+<p class="hang"><span class="smcap">Nuttall, G.H.F.</span> Piroplasmosis. <i>Jour. Roy. Inst. of Pub. Health</i>,
+1908. What piroplasma are; diseases produced by them. Biology.</p>
+
+<p class="hang"><span class="smcap">Nuttall, Geo. F.</span>, and co-workers. <i>Canine Piroplasmosis</i>, Parts I
+to VI. <i>Jour. Hyg.</i>, Vol. 4, No. 2, Apr., 1904, to Vol. 7, No. 2,
+Apr., 1907. A thorough discussion of the disease, the parasite
+which causes it and the ticks which convey it.</p>
+
+<p class="hang"><span class="smcap">Pocock, R.I.</span> Ticks. In Albutt and Rolleston's <i>System of Med.</i>, II,
+1907, pp. 187&ndash;203. Classification; description of the best-known
+pathogenic species. Extended bibliography.</p>
+
+<p class="hang"><span class="smcap">Skinner, B.</span> Preliminary Note on Ticks Infecting the Rats Suffering
+from the Plague. <i>Brit. Med. Jour.</i>, Vol. II, 1907, p. 457. Records
+taking tick on a plague-sick rat and finding bacilli similar to
+plague bacilli in connection with it.</p>
+
+<p class="hang"><span class="smcap">Smith, T., and Kilborne, F.L.</span> Texas Fever. <i>U.S. Dept. Agric.
+Bureau of Animal Industry, Bull. No. 1</i>, 1893. Records of the
+experiments showing disease to be transmitted by ticks.</p>
+
+<p class="hang"><span class="smcap">Wellman, F.C.</span> Preliminary Note on Some Bodies Found in
+Ticks&mdash;<i>Ornithodoros moubata</i>&mdash;Fed on Blood Containing Embryos of
+Filaria. <i>Brit. Med. Jour.</i>, July 20, 1907, p. 142.<span class='pagenum'><a name="Page_216" id="Page_216">[Pg 216]</a></span> Believes that
+<i>F. perstans</i> is conveyed from man to tick and from tick to man. </p></div>
+
+
+<p class="center">KALA-AZAR AND BEDBUGS</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Girault, A.A.</span> The Indian Bedbug and Kala-azar Disease. <i>Sci.</i>,
+N.S., Vol. XXV, 1907, p. 1004. Indian bedbug is <i>C. rotundatus</i>
+Sig. Its distribution. Summary of Dr. Patton's paper on
+"Preliminary Report on the Development of the Leishman-Donovan Body
+in the Bedbug."</p>
+
+<p class="hang"><span class="smcap">Patton, W.S.</span> The Development of the Leishman-Donovan Parasite in
+<i>Cimex rotundatus</i>. <i>Scientific Mem. of Gov. of India</i>, Nos. 27 and
+31, 1907. Traces the development of this parasite; believes that
+the bedbug is concerned in transmitting this disease.</p>
+
+<p class="hang">See also Manson's <i>Tropical Diseases</i>, pp. 178&ndash;190.</p></div>
+
+
+<p class="center">TEXT OR REFERENCE BOOKS IN WHICH THE RELATION OF INSECTS TO VARIOUS
+DISEASES IS DISCUSSED</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Abbott, A.C.</span> Hygiene of Transmissible Diseases. Phil., 1899.
+Causes, modes of dissemination, prevention, treatment of infectious
+and contagious diseases.</p>
+
+<p class="hang"><span class="smcap">Allbutt, T.C., and Rolleston, H.D.</span> A System of Medicine. London,
+1907. Vol. II, Pt. II, contains sections on tropical diseases;
+animal parasites and the diseases they carry and zo&ouml;logical
+articles dealing with Protozoa, mosquitoes, flies and ticks. All
+articles have bibliographies, some of them quite extensive.</p>
+
+<p class="hang"><span class="smcap">Balfour, Andrew.</span> Review of Recent Advances in Tropical Medicine.
+Supplement to <i>Third Rept. Wellcome Research Lab.</i>, London, 1908.
+Notes, extracts and references in regard to important articles
+during the preceding few months.</p>
+
+<p><span class='pagenum'><a name="Page_217" id="Page_217">[Pg 217]</a></span></p><p class="hang"><span class="smcap">Daniels, C.W.</span> Studies in Laboratory Work, 2d ed., London, 1907. A
+good discussion of animal parasites in the blood and blood-plasma;
+development of malarial parasites in mosquitoes; flies, fleas,
+lice, bedbugs, ticks, etc.</p>
+
+<p class="hang"><span class="smcap">Jackson, C.W.</span> Tropical Medicine. Phil., 1907. Discusses diseases
+due to bacteria and the parasites and uncertain causes. Splendid
+recent summary of the various ways in which the different diseases
+are disseminated.</p>
+
+<p class="hang"><span class="smcap">Langfeld, Millard.</span> Introduction to Infectious and Parasitic
+Diseases, Including Their Causes and Manner of Transmission. Phil.,
+1907. Chapters on infection, animal parasites, avenues of exit and
+portals of entry of infectious agents and parasites into the body.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Lectures on Tropical Diseases. London, 1905.
+Delivered at Cooper Medical College, 1905. Discusses several of
+these diseases. Last chapter on problems in tropical medicine.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Tropical Diseases. London, 1907, Diseases of the
+tropics discussed in a very comprehensive manner. Considerable
+attention given to the part played by insects in the transmission
+of many of the diseases.</p>
+
+<p class="hang"><span class="smcap">Metchnikoff, E.</span> Immunity in Infectious Diseases. (Trans. from the
+French by F.G. Binnie.) Cambridge, 1905. Splendid discussion of
+various kinds of immunity. Insects referred to occasionally.</p>
+
+<p class="hang"><span class="smcap">Osler's</span> <i>Modern Medicine</i>. Vol. I, 1907, Pt. VI, Diseases Caused by
+Protozoa. Part VII, Diseases Caused by Animal Parasites. Vol. II,
+1907, Infectious Diseases. Vol. III, Infectious Diseases (cont.).
+One of the best and most modern text-books; the volumes noted above
+contain many references to the relation of insects to the
+particular diseases under discussion.</p>
+
+<p class="hang"><span class="smcap">Park, W.H.</span> Pathogenic Micro-organisms, Including Bacteria and
+Protozoa. N.Y., 1908. These organisms comprehensively treated.</p>
+
+<p><span class='pagenum'><a name="Page_218" id="Page_218">[Pg 218]</a></span></p><p class="hang"><span class="smcap">Ricketts, H.T.</span> Infection, Immunity and Serum Therapy. Chicago,
+1906. Chapters on parasitism, infection, contagion, immunity,
+various diseases, etc.</p>
+
+<p class="hang"><span class="smcap">Scheube, B.</span> The Diseases of Warm Countries: a Handbook for Medical
+Men. Trans. from Ger. by Pauline Falcke, London, 1903. Sections on
+general infectious diseases, diseases caused by animal parasites,
+etc. Good bibliography of each disease treated.</p>
+
+<p class="hang"><span class="smcap">Simpson, W.J.R.</span> The Principles of Hygiene as Applied to Tropical
+and Subtropical Climates. London, 1908. Occasional references to
+flies and mosquitoes as carriers of disease. Chapter XV deals with
+malaria and other diseases caused by mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Wilson, J.C.</span> Modern Clinical Medicine; Infectious Diseases. New
+York and London, 1905. Chapters on yellow fever, malarial diseases
+and plague; contains references to the relation of insects to these
+diseases. </p></div>
+
+
+<p class="center">MISCELLANEOUS ARTICLES</p>
+
+<div class="blockquot"><p class="hang"><span class="smcap">Balfour, Andrew.</span> Further Observations on Fowl Spiroch&aelig;tosis. <i>Jour.
+Trop. Med. &amp; Hyg.</i>, 12, Oct. 1, 1909, pp. 285&ndash;289. Ticks and lice
+may carry this disease.</p>
+
+<p class="hang"><span class="smcap">Chittenden, F.H.</span> Harvest-mites or "Chiggers." <i>Circular 77, U.S.
+Dept. Agric. Bur. Ento.</i>, 1906, pp. 1&ndash;16. Descriptions of these
+pests and their habits. Remedies.</p>
+
+<p class="hang"><span class="smcap">Doty, A.H.</span> The Means by Which Infectious Diseases Are Transmitted.
+<i>Amer. Jour. of Med. Sci.</i>, 138, July, 1909, pp. 30&ndash;39. Flies and
+mosquitoes as disseminators of disease briefly discussed.</p>
+
+<p class="hang"><span class="smcap">Duncan, F.M.</span> Industrial Entomology: the Economic Importance of a
+Study of Insect Life. <i>Jour. Roy. Soc. Arts</i>, May 22, 1908, pp.
+688&ndash;696. A very interesting review of the subject of insects and
+disease.</p>
+
+<p><span class='pagenum'><a name="Page_219" id="Page_219">[Pg 219]</a></span></p><p class="hang"><span class="smcap">Flexner, Simon.</span> <i>Science</i>, N.S., Vol. 27, No. 682, Jan. 24, 1908,
+pp. 133&ndash;136. On these pages the author discusses relation of
+bacteria and Protozoa to human diseases.</p>
+
+<p class="hang"><span class="smcap">Goldberger, Jos., and Shamberg, J.F.</span> Epidemic of an <i>Utricaroid
+dermatitis</i> Due to a Small Mite (<i>Pediculoides ventricosus</i>) in the
+Straw of Mattresses. <i>Pub. Health Rept., Pub. Health and Mar.
+Hospt. Ser.</i>, July 9, 1909, Vol. XXIV, No. 28. Experiments showed
+that a certain skin disease occurring during summer was due to this
+mite.</p>
+
+<p class="hang"><span class="smcap">Gorgas, W.C.</span> The Part Sanitation Is Playing in the Construction of
+the Panama Canal. <i>Jour. Amer. Med. Assn.</i>, 53, Aug. 21, 1909, pp.
+597&ndash;599. Shows the changes that have been brought about by modern
+sanitation and the destroying of the mosquitoes' breeding-places.</p>
+
+<p class="hang"><span class="smcap">Howard, L.O.</span> Hydrocyanic-acid Gas Against Household Insects.
+<i>Circular 46, U.S. Dept. Agric., Div. of Ento.</i>, 1902. Directions
+for handling this dangerous gas.</p>
+
+<p class="hang"><span class="smcap">King, A.F.G.</span> Insects and Disease; Mosquitoes and Malaria. <i>Pop.
+Sci. Mo.</i>, XXIII, 1883, pp. 644&ndash;658. Extended article in which the
+author sums up the observations which led him to believe that
+malaria and other diseases were transmitted by the mosquito. One of
+the earliest articles on this subject; refers to an article in <i>New
+Orleans Med. &amp; Surg. Jour.</i>, Vol. IV, 1848, pp. 563&ndash;601, by Josiah
+Nott, who maintained that yellow fever was carried by mosquitoes.</p>
+
+<p class="hang"><span class="smcap">Manson, Patrick.</span> Recent Advances in Science and Their Bearing on
+Medicine and Surgery. <i>Jour. Trop. Med. &amp; Hyg.</i>, XI, pp. 337&ndash;338,
+Sept. 16, 1908. Discussion of parasites and disease and their
+methods of dissemination.</p>
+
+<p class="hang"><span class="smcap">Newstead, R., Dutton, J.E., and Todd, J.L.</span> Insects and Other
+Arthropoda Collected in the Congo Free State. <i>Ann. Trop. Med. &amp;
+Parasit.</i>, Vol. 1, No. 1, Feb. 1, 1907, pp. 3&ndash;100. An interesting
+paper giving notes on many insects that cause or carry disease.</p>
+
+<p><span class='pagenum'><a name="Page_220" id="Page_220">[Pg 220]</a></span></p><p class="hang"><span class="smcap">Nuttall, G.H.F.</span> Spiroch&aelig;tosis in Man and Animals. <i>Jour. of Roy.
+Inst. of Pub. Health</i>, 1908. Why Spiroch&aelig;tes should be regarded as
+Protozoa. Classification; list of blood-inhabiting forms; relapsing
+fevers; transmission by ticks and other Arthropods.</p>
+
+<p class="hang"><span class="smcap">O'Connell, M.D.</span> The Oversea Transport of Insect-borne Disease.
+<i>Jour. Trop. Med. &amp; Hyg.</i>, XI, 43, Feb. 1, 1908. Refers to article
+in same journal (Jan. 15) and points out that malaria is very
+likely to be transmitted by mosquitoes in this way.</p>
+
+<p class="hang"><span class="smcap">Osborn, Herbert.</span> Insects Affecting Domestic Animals. <i>U.S. Dept. of
+Agric., Div. of Ento., Bull. No. 5</i>, N.S., 1896. Discusses the
+various insect pests of man and domestic animals Host lists.
+Bibliography.</p>
+
+<p class="hang"><span class="smcap">Rickets, H.T., and Wilder, R.M.</span> The Typhus Fever of Mexico. <i>Jour.
+Amer. Med. Assn.</i>, LIV, No. 6, Feb. 5, 1910, p. 463. Believes this
+disease is transmitted by insects, probably lice.</p>
+
+<p class="hang"><span class="smcap">Ritchie, James.</span> A Review of Current Theories Regarding Immunity.
+<i>Jour. Hyg.</i>, 2, 1902, pp. 215&ndash;285, and pp. 452&ndash;464. Discussion of
+various theories. Bibliography.</p>
+
+<p class="hang"><span class="smcap">Shipley, A.E.</span> On the Relation of Certain Cestode and Nematoda
+Parasites to Bacterial Disease. <i>Jour. of Eco. Biol.</i>, 4, 1909, pp.
+61&ndash;71. Shows that these parasites may often cause serious diseases
+by opening the way for malignant germs.</p>
+
+<p class="hang"><span class="smcap">Ward, H.B.</span> Spirochetes and Their Relationship to Other Organisms.
+<i>Amer. Nat.</i>, 42, 1908, No. 498, pp. 374&ndash;387. Still undecided as to
+whether they belong with bacteria or Protozoa, probably the latter.</p>
+
+<p class="hang"><span class="smcap">Ward, H.B.</span> The Relation of Animals to Disease. <i>Science</i>, N.S., 22,
+1905, pp. 193&ndash;203. An interesting, comprehensive review of the
+subject.</p>
+
+<p class="hang"><span class="smcap">Ward, Henry B.</span> Relation of Animals to Disease. <i>Transactions of
+Amer. Micro. Soc.</i>, Vol. 27, 1907, pp. 5&ndash;20. The various ways in
+which animals may produce or carry disease.</p>
+
+<p><span class='pagenum'><a name="Page_221" id="Page_221">[Pg 221]</a></span></p><p class="hang">The Oversea Transport of Insect-borne Diseases. Editorial in
+<i>Jour. Trop. Med. &amp; Hyg.</i>, XI, Jan. 15, 1908, pp. 22&ndash;23. Points out
+the danger of yellow fever, plague and other diseases being borne
+overseas by infected insects.</p>
+
+<p class="hang">The Society for the Destruction of Vermin. Editorial in <i>Jour.
+Trop. Med. &amp; Hyg.</i>, XI, Apr. 15, 1908, p. 124. Tells of
+organization of such society and its purposes. </p></div>
+<p><span class='pagenum'><a name="Page_222" id="Page_222">[Pg 222]</a></span></p>
+
+
+
+<hr /><p><span class='pagenum'><a name="Page_223" id="Page_223">[Pg 223]</a></span></p>
+<h2><a name="INDEX" id="INDEX"></a>INDEX</h2>
+
+
+<p class="index">
+Adams, S.H., <a href="#Page_132">132</a>.<br />
+<br />
+Advisory Committee, <a href="#Page_146">146</a>.<br />
+<br />
+Agramonte, Dr. Aristides, <a href="#Page_123">123</a>.<br />
+<br />
+Alimentary canal, fly larv&aelig; in, <a href="#Page_49">49</a>.<br />
+<br />
+Am&#339;ba, <a href="#Page_19">19</a>.<br />
+<br />
+Anopheles,<br />
+<span style="margin-left: 1em;">adults, <a href="#Page_91">91</a>;</span><br />
+<span style="margin-left: 1em;">eggs, <a href="#Page_92">92</a>;</span><br />
+<span style="margin-left: 1em;">habits of adults, <a href="#Page_94">94</a>;</span><br />
+<span style="margin-left: 1em;">larv&aelig;, <a href="#Page_78">78</a>, <a href="#Page_79">79</a>, <a href="#Page_93">93</a>;</span><br />
+<span style="margin-left: 1em;">pup&aelig;, <a href="#Page_93">93</a>;</span><br />
+<span style="margin-left: 1em;">resting position, <a href="#Page_92">92</a>;</span><br />
+<span style="margin-left: 1em;">species in U.S., <a href="#Page_92">92</a>.</span><br />
+<br />
+Anthrax, <a href="#Page_44">44</a>;<br />
+<span style="margin-left: 1em;">and flies, <a href="#Page_70">70</a>.</span><br />
+<br />
+Arthropoda, <a href="#Page_26">26</a>.<br />
+<br />
+Asexual reproduction, <a href="#Page_111">111</a>.<br />
+<br />
+<br />
+Bacillus,<br />
+<span style="margin-left: 1em;">anthracis, <a href="#Page_44">44</a>;</span><br />
+<span style="margin-left: 1em;">icteroides, <a href="#Page_124">124</a>;</span><br />
+<span style="margin-left: 1em;">lepr&aelig;, <a href="#Page_171">171</a>;</span><br />
+<span style="margin-left: 1em;">pestis, <a href="#Page_150">150</a>.</span><br />
+<br />
+Bacillus carriers, <a href="#Page_66">66</a>.<br />
+<br />
+Back-swimmers, <a href="#Page_100">100</a>.<br />
+<br />
+Bacteria, <a href="#Page_15">15</a>;<br />
+<span style="margin-left: 1em;">saprophytic and parasitic, <a href="#Page_17">17</a>;</span><br />
+<span style="margin-left: 1em;">effect on host, <a href="#Page_18">18</a>;</span><br />
+<span style="margin-left: 1em;">dissemination, <a href="#Page_18">18</a>.</span><br />
+<br />
+Bedbugs, <a href="#Page_54">54</a>, <a href="#Page_147">147</a>.<br />
+<br />
+Banks, Nathan, <a href="#Page_34">34</a>.<br />
+<br />
+Bell-animalcule, <a href="#Page_22">22</a>.<br />
+<br />
+Berne, <a href="#Page_51">51</a>.<br />
+<br />
+Birds as enemies of mosquitoes, <a href="#Page_99">99</a>.<br />
+<br />
+Black-flies, <a href="#Page_46">46</a>.<br />
+<br />
+Blackheads, <a href="#Page_35">35</a>.<br />
+<br />
+Blow-flies, <a href="#Page_48">48</a>.<br />
+<br />
+Blue, Dr. Rupert, <a href="#Page_143">143</a>.<br />
+<br />
+Blue-bottle flies, <a href="#Page_48">48</a>.<br />
+<br />
+Bot-flies, <a href="#Page_50">50</a>.<br />
+<br />
+Break-bone fever, <a href="#Page_169">169</a>.<br />
+<br />
+Breeze-fly, <a href="#Page_44">44</a>.<br />
+<br />
+Buffalo-gnats, <a href="#Page_46">46</a>.<br />
+<br />
+<br />
+Calliphora vomitoria, <a href="#Page_48">48</a>.<br />
+<br />
+Camphor, for mosquitoes, <a href="#Page_102">102</a>.<br />
+<br />
+Cancer, <a href="#Page_36">36</a>.<br />
+<br />
+Carroll, Dr. James, <a href="#Page_123">123</a>.<br />
+<br />
+Castor-bean tick, <a href="#Page_27">27</a>.<br />
+<br />
+Cattle tick, <a href="#Page_29">29</a>.<br />
+<br />
+Cedar oil, for mosquitoes, <a href="#Page_102">102</a>.<br />
+<br />
+Ceratophyllus,<br />
+<span style="margin-left: 1em;">faciatus, <a href="#Page_153">153</a>;</span><br />
+<span style="margin-left: 1em;">acutus, <a href="#Page_156">156</a>.</span><br />
+<br />
+Cesspools, <a href="#Page_72">72</a>.<br />
+<br />
+Chigger, <a href="#Page_53">53</a>.<br />
+<br />
+Chigger-flea, <a href="#Page_53">53</a>.<br />
+<br />
+Chigo, <a href="#Page_30">30</a>, <a href="#Page_39">39</a>.<br />
+<br />
+Chigoe, <a href="#Page_53">53</a>.<br />
+<br />
+Cholera, <a href="#Page_68">68</a>.<br />
+<br />
+Chrysomyia macellaria, <a href="#Page_47">47</a>.<br />
+<br />
+Cimex,<br />
+<span style="margin-left: 1em;">lectularis, <a href="#Page_54">54</a>;</span><br />
+<span style="margin-left: 1em;">rotundatus, <a href="#Page_173">173</a>.</span><br />
+<br />
+Contagious diseases, <a href="#Page_8">8</a>.<br />
+<br />
+Conjugation, <a href="#Page_20">20</a>.<br />
+<br />
+Cooley, Prof. R.A., <a href="#Page_33">33</a>.<br />
+<br />
+Craig, Dr. C.F., <a href="#Page_118">118</a>.<br />
+<br />
+Ctenocephalus,<br />
+<span style="margin-left: 1em;">canis, <a href="#Page_154">154</a>;</span><br />
+<span style="margin-left: 1em;">felis, <a href="#Page_154">154</a>.</span><br />
+<br />
+Culex,<br />
+<span style="margin-left: 1em;">fatigans, <a href="#Page_96">96</a>, <a href="#Page_170">170</a>;</span><br />
+<span style="margin-left: 1em;">pipiens, <a href="#Page_98">98</a>.</span><br />
+<br />
+<br />
+<span class='pagenum'><a name="Page_224" id="Page_224">[Pg 224]</a></span>Dengue, <a href="#Page_169">169</a>.<br />
+<br />
+Dermatobia cyaniventris, <a href="#Page_51">51</a>.<br />
+<br />
+Dermatophilus penetrans, <a href="#Page_53">53</a>.<br />
+<br />
+Diarrhea, <a href="#Page_69">69</a>.<br />
+<br />
+Diptera, <a href="#Page_43">43</a>.<br />
+<br />
+Diving beetles, <a href="#Page_100">100</a>.<br />
+<br />
+Dragon-flies, <a href="#Page_99">99</a>.<br />
+<br />
+Dysentery, <a href="#Page_20">20</a>.<br />
+<br />
+<br />
+Eggs,<br />
+<span style="margin-left: 1em;">of flies, <a href="#Page_63">63</a>;</span><br />
+<span style="margin-left: 1em;">of mosquitoes, <a href="#Page_77">77</a>;</span><br />
+<span style="margin-left: 1em;">of Anopheles, <a href="#Page_92">92</a>.</span><br />
+<br />
+Egyptian opthalmia, <a href="#Page_52">52</a>.<br />
+<br />
+Elephantiasis, <a href="#Page_164">164</a>.<br />
+<br />
+Enemies of mosquitoes, <a href="#Page_97">97</a>.<br />
+<br />
+Enteritis, <a href="#Page_69">69</a>.<br />
+<br />
+Euglena, <a href="#Page_21">21</a>.<br />
+<br />
+Eye-worm, <a href="#Page_12">12</a>.<br />
+<br />
+<br />
+Face-mite, <a href="#Page_35">35</a>.<br />
+<br />
+Fighting mosquitoes,<br />
+<span style="margin-left: 1em;">adults, <a href="#Page_101">101</a>;</span><br />
+<span style="margin-left: 1em;">larv&aelig;, <a href="#Page_103">103</a>.</span><br />
+<br />
+Fiji Islands, Anopheles in, <a href="#Page_117">117</a>.<br />
+<br />
+Filaria bancrofti, <a href="#Page_164">164</a>.<br />
+<br />
+Finlay, Dr. Charles, <a href="#Page_124">124</a>.<br />
+<br />
+Fish, <a href="#Page_100">100</a>.<br />
+<br />
+Flagella, <a href="#Page_20">20</a>.<br />
+<br />
+Fleas, <a href="#Page_52">52</a>;<br />
+<span style="margin-left: 1em;">and plague, <a href="#Page_142">142</a>, <a href="#Page_145">145</a>, <a href="#Page_147">147</a>;</span><br />
+<span style="margin-left: 1em;">structure and habits, <a href="#Page_151">151</a>;</span><br />
+<span style="margin-left: 1em;">common species, <a href="#Page_153">153</a>;</span><br />
+<span style="margin-left: 1em;">on ground squirrels, <a href="#Page_156">156</a>;</span><br />
+<span style="margin-left: 1em;">remedies for, <a href="#Page_157">157</a>.</span><br />
+<br />
+Flies, <a href="#Page_43">43</a>;<br />
+<span style="margin-left: 1em;">and typhoid, <a href="#Page_65">65</a>;</span><br />
+<span style="margin-left: 1em;">specks, <a href="#Page_66">66</a>;</span><br />
+<span style="margin-left: 1em;">and various diseases, <a href="#Page_68">68</a>.</span><br />
+<br />
+Flesh-flies, <a href="#Page_48">48</a>.<br />
+<br />
+Fumigating for mosquitoes, <a href="#Page_102">102</a>.<br />
+<br />
+<br />
+Gad-fly, <a href="#Page_43">43</a>.<br />
+<br />
+Glossina palpalis, <a href="#Page_163">163</a>.<br />
+<br />
+Golgi, Camillo, <a href="#Page_109">109</a>.<br />
+<br />
+Grassi, Prof. G.B., <a href="#Page_118">118</a>.<br />
+<br />
+Gray-flies, <a href="#Page_47">47</a>.<br />
+<br />
+Ground squirrels and plague, <a href="#Page_155">155</a>.<br />
+<br />
+Guinea-worm, <a href="#Page_11">11</a>.<br />
+<br />
+<br />
+H&aelig;mam&#339;ba, <a href="#Page_109">109</a>.<br />
+<br />
+H&aelig;matobia, <a href="#Page_45">45</a>.<br />
+<br />
+H&aelig;mosporidiida, <a href="#Page_24">24</a>.<br />
+<br />
+H&aelig;motopinus spinulosus, <a href="#Page_55">55</a>.<br />
+<br />
+Harvest-mite, <a href="#Page_37">37</a>.<br />
+<br />
+Havana, yellow fever in, <a href="#Page_131">131</a>.<br />
+<br />
+Hawaii, mosquitoes in, <a href="#Page_98">98</a>.<br />
+<br />
+Hemiptera, <a href="#Page_54">54</a>.<br />
+<br />
+Homalomyia canicularis, <a href="#Page_49">49</a>.<br />
+<br />
+Hoplopsyllus anomalus, <a href="#Page_156">156</a>.<br />
+<br />
+Horse bot-flies, <a href="#Page_50">50</a>.<br />
+<br />
+House-flies, <a href="#Page_57">57</a>;<br />
+<span style="margin-left: 1em;">structure, <a href="#Page_59">59</a>;</span><br />
+<span style="margin-left: 1em;">how they carry bacteria, <a href="#Page_62">62</a>;</span><br />
+<span style="margin-left: 1em;">life-history and habits, <a href="#Page_63">63</a>;</span><br />
+<span style="margin-left: 1em;">fighting, <a href="#Page_71">71</a>;</span><br />
+<span style="margin-left: 1em;">and typhoid, <a href="#Page_65">65</a>.</span><br />
+<br />
+Horse-flies, <a href="#Page_43">43</a>.<br />
+<br />
+Howard, Dr. L.O., <a href="#Page_59">59</a>, <a href="#Page_73">73</a>.<br />
+<br />
+Hyperparasitism, <a href="#Page_3">3</a>.<br />
+<br />
+<br />
+Immunity, <a href="#Page_5">5</a>.<br />
+<br />
+Indian Plague Commission, <a href="#Page_144">144</a>.<br />
+<br />
+Infectious diseases, <a href="#Page_8">8</a>.<br />
+<br />
+Infusoria, <a href="#Page_22">22</a>.<br />
+<br />
+Insects,<br />
+<span style="margin-left: 1em;">cause or carry disease, <a href="#Page_40">40</a>;</span><br />
+<span style="margin-left: 1em;">numbers, <a href="#Page_40">40</a>;</span><br />
+<span style="margin-left: 1em;">annual loss caused by, <a href="#Page_41">41</a>;</span><br />
+<span style="margin-left: 1em;">how they carry disease germs, <a href="#Page_55">55</a>.</span><br />
+<br />
+Irrigating ditches, <a href="#Page_104">104</a>.<br />
+<br />
+Itch-mite, <a href="#Page_36">36</a>.<br />
+<br />
+<br />
+<span class='pagenum'><a name="Page_225" id="Page_225">[Pg 225]</a></span>Jackson, Dr. D.D., <a href="#Page_67">67</a>.<br />
+<br />
+Jennings, <a href="#Page_22">22</a>.<br />
+<br />
+Jiggers, <a href="#Page_38">38</a>, <a href="#Page_53">53</a>.<br />
+<br />
+Jigger-flea, <a href="#Page_53">53</a>.<br />
+<br />
+<br />
+Kala-azar, <a href="#Page_173">173</a>.<br />
+<br />
+Kerosene, <a href="#Page_104">104</a>.<br />
+<br />
+Koch, <a href="#Page_44">44</a>.<br />
+<br />
+<br />
+L&aelig;mopsylla cheopus, <a href="#Page_153">153</a>.<br />
+<br />
+Lamprey-eel, <a href="#Page_2">2</a>.<br />
+<br />
+Lancisi, J.M., <a href="#Page_107">107</a>.<br />
+<br />
+Larv&aelig;,<br />
+<span style="margin-left: 1em;">of flies, <a href="#Page_64">64</a>;</span><br />
+<span style="margin-left: 1em;">of mosquitoes, <a href="#Page_78">78</a>.</span><br />
+<br />
+Laveran, A., <a href="#Page_108">108</a>.<br />
+<br />
+Laverania, <a href="#Page_109">109</a>.<br />
+<br />
+Lazear, Dr. Jessie W., <a href="#Page_123">123</a>.<br />
+<br />
+Leeuwenhoek, Anton von, <a href="#Page_22">22</a>.<br />
+<br />
+Lepra bacillus, <a href="#Page_36">36</a>.<br />
+<br />
+Leprosy, <a href="#Page_36">36</a>, <a href="#Page_70">70</a>, <a href="#Page_171">171</a>.<br />
+<br />
+Lice, <a href="#Page_54">54</a>.<br />
+<br />
+Linn&aelig;us, <a href="#Page_76">76</a>.<br />
+<br />
+Little house-fly, <a href="#Page_49">49</a>.<br />
+<br />
+Lock-jaw, <a href="#Page_18">18</a>.<br />
+<br />
+Low, Dr. A., <a href="#Page_118">118</a>.<br />
+<br />
+Lucilia spp., <a href="#Page_48">48</a>.<br />
+<br />
+Lugger, Prof. Otto, <a href="#Page_38">38</a>.<br />
+<br />
+<br />
+Malaria,<br />
+<span style="margin-left: 1em;">early theories in regard to, <a href="#Page_106">106</a>;</span><br />
+<span style="margin-left: 1em;">parasite that causes, <a href="#Page_108">108</a>;</span><br />
+<span style="margin-left: 1em;">life history of parasite, <a href="#Page_109">109</a>;</span><br />
+<span style="margin-left: 1em;">parasite in mosquito, <a href="#Page_113">113</a>;</span><br />
+<span style="margin-left: 1em;">summary, <a href="#Page_117">117</a>;</span><br />
+<span style="margin-left: 1em;">experiments, <a href="#Page_118">118</a>.</span><br />
+<br />
+Maggots, <a href="#Page_63">63</a>.<br />
+<br />
+Malta or Mediterranean fever, <a href="#Page_171">171</a>.<br />
+<br />
+Mange, <a href="#Page_37">37</a>.<br />
+<br />
+Manure-fly, <a href="#Page_59">59</a>.<br />
+<br />
+Manson, Sir Patrick, <a href="#Page_112">112</a>, <a href="#Page_123">123</a>.<br />
+<br />
+Mastigophora, <a href="#Page_20">20</a>.<br />
+<br />
+Melanin, <a href="#Page_110">110</a>.<br />
+<br />
+Micrococcus melitensis, <a href="#Page_171">171</a>.<br />
+<br />
+Microbes, <a href="#Page_10">10</a>.<br />
+<br />
+Mites, <a href="#Page_26">26</a>, <a href="#Page_35">35</a>.<br />
+<br />
+Mosquito, <a href="#Page_76">76</a>;<br />
+<span style="margin-left: 1em;">abdomen, <a href="#Page_86">86</a>;</span><br />
+<span style="margin-left: 1em;">adults, <a href="#Page_81">81</a>;</span><br />
+<span style="margin-left: 1em;">Anopheles, <a href="#Page_91">91</a>;</span><br />
+<span style="margin-left: 1em;">how they bite, <a href="#Page_84">84</a>;</span><br />
+<span style="margin-left: 1em;">effect of bite, <a href="#Page_87">87</a>;</span><br />
+<span style="margin-left: 1em;">blood, <a href="#Page_90">90</a>;</span><br />
+<span style="margin-left: 1em;">how they breathe, <a href="#Page_89">89</a>;</span><br />
+<span style="margin-left: 1em;">classification, <a href="#Page_91">91</a>;</span><br />
+<span style="margin-left: 1em;">and dengue, <a href="#Page_169">169</a>;</span><br />
+<span style="margin-left: 1em;">eggs, <a href="#Page_77">77</a>;</span><br />
+<span style="margin-left: 1em;">and elephantiasis, <a href="#Page_164">164</a>;</span><br />
+<span style="margin-left: 1em;">enemies, <a href="#Page_77">77</a>;</span><br />
+<span style="margin-left: 1em;">fighting, adults, <a href="#Page_101">101</a>;</span><br />
+<span style="margin-left: 1em;">larv&aelig;, <a href="#Page_103">103</a>;</span><br />
+<span style="margin-left: 1em;">larv&aelig;, <a href="#Page_78">78</a>;</span><br />
+<span style="margin-left: 1em;">and malaria, <a href="#Page_106">106</a>;</span><br />
+<span style="margin-left: 1em;">malarial parasite in, <a href="#Page_113">113</a>;</span><br />
+<span style="margin-left: 1em;">mouth-parts, <a href="#Page_83">83</a>;</span><br />
+<span style="margin-left: 1em;">other species, <a href="#Page_96">96</a>;</span><br />
+<span style="margin-left: 1em;">pup&aelig;, <a href="#Page_80">80</a>;</span><br />
+<span style="margin-left: 1em;">salivary glands, <a href="#Page_87">87</a>;</span><br />
+<span style="margin-left: 1em;">thorax, <a href="#Page_85">85</a>;</span><br />
+<span style="margin-left: 1em;">and yellow fever, <a href="#Page_94">94</a>, <a href="#Page_120">120</a>.</span><br />
+<br />
+Mouth-parts,<br />
+<span style="margin-left: 1em;">of fly, <a href="#Page_60">60</a>;</span><br />
+<span style="margin-left: 1em;">of mosquito, <a href="#Page_83">83</a>.</span><br />
+<br />
+Mus,<br />
+<span style="margin-left: 1em;">norvegicus, <a href="#Page_154">154</a>;</span><br />
+<span style="margin-left: 1em;">rattus, <a href="#Page_154">154</a>.</span><br />
+<br />
+<br />
+Nanga, <a href="#Page_45">45</a>.<br />
+<br />
+Nematodes, <a href="#Page_164">164</a>.<br />
+<br />
+New Orleans, yellow fever in, <a href="#Page_120">120</a>, <a href="#Page_132">132</a>.<br />
+<br />
+Noctiluca, <a href="#Page_21">21</a>.<br />
+<br />
+No-see-ums, <a href="#Page_46">46</a>.<br />
+<br />
+<br />
+Ochromyia anthropophaga, <a href="#Page_49">49</a>.<br />
+<br />
+Oil of citronella, <a href="#Page_102">102</a>.<br />
+<br />
+Oil of pennyroyal, <a href="#Page_102">102</a>.<br />
+<br />
+<span class='pagenum'><a name="Page_226" id="Page_226">[Pg 226]</a></span>Oriental sore, <a href="#Page_174">174</a>.<br />
+<br />
+Ornithodorus moubata, <a href="#Page_34">34</a>.<br />
+<br />
+Oscinid&aelig;, <a href="#Page_52">52</a>.<br />
+<br />
+Otospermophilus beecheyi, <a href="#Page_155">155</a>.<br />
+<br />
+Oxwarbles, <a href="#Page_50">50</a>.<br />
+<br />
+<br />
+Panama Canal zone, <a href="#Page_135">135</a>.<br />
+<br />
+Param&#339;cium, <a href="#Page_22">22</a>.<br />
+<br />
+Parasite,<br />
+<span style="margin-left: 1em;">defined, <a href="#Page_1">1</a>;</span><br />
+<span style="margin-left: 1em;">classes of, <a href="#Page_4">4</a>;</span><br />
+<span style="margin-left: 1em;">in new regions, <a href="#Page_5">5</a>;</span><br />
+<span style="margin-left: 1em;">diseases caused by, <a href="#Page_7">7</a>;</span><br />
+<span style="margin-left: 1em;">effect on host, <a href="#Page_9">9</a>;</span><br />
+<span style="margin-left: 1em;">relation to host, <a href="#Page_14">14</a>.</span><br />
+<br />
+Parasitism, <a href="#Page_3">3</a>.<br />
+<br />
+Pasteur, L., <a href="#Page_44">44</a>.<br />
+<br />
+Pearls, <a href="#Page_13">13</a>.<br />
+<br />
+Piroplasma bigeminum, <a href="#Page_29">29</a>.<br />
+<br />
+Plague,<br />
+<span style="margin-left: 1em;">early history of, <a href="#Page_142">142</a>;</span><br />
+<span style="margin-left: 1em;">fleas that transmit, <a href="#Page_153">153</a>;</span><br />
+<span style="margin-left: 1em;">and flies, <a href="#Page_70">70</a>;</span><br />
+<span style="margin-left: 1em;">and ground squirrels, <a href="#Page_155">155</a>;</span><br />
+<span style="margin-left: 1em;">how combatted in San Francisco, <a href="#Page_143">143</a>;</span><br />
+<span style="margin-left: 1em;">results of other investigations, <a href="#Page_150">150</a>;</span><br />
+<span style="margin-left: 1em;">Verjbitski's experiments, <a href="#Page_147">147</a>;</span><br />
+<span style="margin-left: 1em;">work of Indian Plague Commission, <a href="#Page_146">146</a>.</span><br />
+<br />
+Plasmodium, <a href="#Page_109">109</a>.<br />
+<br />
+Protozoa, <a href="#Page_19">19</a>;<br />
+<span style="margin-left: 1em;">classes of, <a href="#Page_20">20</a>.</span><br />
+<br />
+Proboscis,<br />
+<span style="margin-left: 1em;">of fly, <a href="#Page_60">60</a>;</span><br />
+<span style="margin-left: 1em;">of mosquito, <a href="#Page_80">80</a>.</span><br />
+<br />
+Privies, <a href="#Page_72">72</a>.<br />
+<br />
+Privy-fly, <a href="#Page_59">59</a>.<br />
+<br />
+Pseudopodia, <a href="#Page_20">20</a>.<br />
+<br />
+Psoroptes communis, <a href="#Page_37">37</a>.<br />
+<br />
+Pulex irritans, <a href="#Page_154">154</a>.<br />
+<br />
+Punkies, <a href="#Page_46">46</a>.<br />
+<br />
+Pup&aelig;,<br />
+<span style="margin-left: 1em;">of house-flies, <a href="#Page_64">64</a>;</span><br />
+<span style="margin-left: 1em;">of mosquitoes, <a href="#Page_80">80</a>.</span><br />
+<br />
+Pyrethrum, <a href="#Page_102">102</a>.<br />
+<br />
+<br />
+Rats,<br />
+<span style="margin-left: 1em;">and plague, <a href="#Page_143">143</a>, <a href="#Page_145">145</a>;</span><br />
+<span style="margin-left: 1em;">species of, <a href="#Page_154">154</a>.</span><br />
+<br />
+Red-bugs, <a href="#Page_38">38</a>.<br />
+<br />
+Reed, Dr. Walter, <a href="#Page_123">123</a>.<br />
+<br />
+Relapsing fever, <a href="#Page_21">21</a>, <a href="#Page_33">33</a>.<br />
+<br />
+Rhizopoda, <a href="#Page_20">20</a>.<br />
+<br />
+Ricketts, Dr. H.F., <a href="#Page_32">32</a>.<br />
+<br />
+Rio de Janeiro, yellow fever in, <a href="#Page_137">137</a>.<br />
+<br />
+Rocky Mountain spotted fever, <a href="#Page_32">32</a>.<br />
+<br />
+Ross, Ronald, <a href="#Page_112">112</a>.<br />
+<br />
+Rucker, Dr. W.C., <a href="#Page_143">143</a>.<br />
+<br />
+<br />
+Sacculina, <a href="#Page_2">2</a>.<br />
+<br />
+Salivary glands, <a href="#Page_84">84</a>, <a href="#Page_87">87</a>.<br />
+<br />
+Salt marshes, <a href="#Page_97">97</a>, <a href="#Page_105">105</a>.<br />
+<br />
+Sambon, Dr. L.W., <a href="#Page_118">118</a>.<br />
+<br />
+Sand-fleas, <a href="#Page_53">53</a>.<br />
+<br />
+Saprophytic bacteria, <a href="#Page_17">17</a>.<br />
+<br />
+Sarcophaga spp., <a href="#Page_48">48</a>.<br />
+<br />
+Sarcoptes scabiei, <a href="#Page_37">37</a>.<br />
+<br />
+Scab, <a href="#Page_37">37</a>.<br />
+<br />
+Screw-worm, <a href="#Page_47">47</a>.<br />
+<br />
+Seed-ticks, <a href="#Page_27">27</a>, <a href="#Page_30">30</a>.<br />
+<br />
+Sheep bot-flies, <a href="#Page_51">51</a>.<br />
+<br />
+Simmond, Dr. P.L., <a href="#Page_145">145</a>.<br />
+<br />
+Siphonaptera, <a href="#Page_52">52</a>.<br />
+<br />
+Skinner, Dr. H., <a href="#Page_159">159</a>.<br />
+<br />
+Sleeping sickness, <a href="#Page_21">21</a>, <a href="#Page_161">161</a>.<br />
+<br />
+Slipper animalcule, <a href="#Page_22">22</a>.<br />
+<br />
+Small-pox, <a href="#Page_70">70</a>.<br />
+<br />
+Smith, Dr. Theobald, <a href="#Page_29">29</a>.<br />
+<br />
+Smudges, <a href="#Page_102">102</a>.<br />
+<br />
+Sore-eye, <a href="#Page_52">52</a>.<br />
+<br />
+Spiders, <a href="#Page_26">26</a>.<br />
+<br />
+Spiracles, <a href="#Page_89">89</a>.<br />
+<br />
+Spiroch&aelig;ta, <a href="#Page_21">21</a>, <a href="#Page_130">130</a>.<br />
+<br />
+<span class='pagenum'><a name="Page_227" id="Page_227">[Pg 227]</a></span>Spore formation, <a href="#Page_24">24</a>.<br />
+<br />
+Spores, <a href="#Page_24">24</a>.<br />
+<br />
+Sporozoa, <a href="#Page_22">22</a>.<br />
+<br />
+Spotted fever, <a href="#Page_32">32</a>.<br />
+<br />
+Stable-fly, <a href="#Page_44">44</a>, <a href="#Page_75">75</a>.<br />
+<br />
+Stegomyia,<br />
+<span style="margin-left: 1em;">calopus, <a href="#Page_94">94</a>, <a href="#Page_98">98</a>, <a href="#Page_139">139</a>;</span><br />
+<span style="margin-left: 1em;">scutellaris, <a href="#Page_96">96</a>.</span><br />
+<br />
+Sticklebacks, <a href="#Page_101">101</a>.<br />
+<br />
+Stomoxys calcitrans, <a href="#Page_44">44</a>.<br />
+<br />
+Sulphur, <a href="#Page_102">102</a>.<br />
+<br />
+Surra, <a href="#Page_45">45</a>.<br />
+<br />
+<br />
+Tabanus, <a href="#Page_45">45</a>.<br />
+<br />
+Tahiti, mosquitoes in, <a href="#Page_96">96</a>.<br />
+<br />
+Tapeworms, <a href="#Page_2">2</a>.<br />
+<br />
+Tetanus, <a href="#Page_18">18</a>.<br />
+<br />
+Texas fever, <a href="#Page_28">28</a>.<br />
+<br />
+Theobald, Dr. F.V., <a href="#Page_76">76</a>.<br />
+<br />
+Ticks, <a href="#Page_26">26</a>.<br />
+<br />
+Tide-water minnows, <a href="#Page_101">101</a>.<br />
+<br />
+Tobacco smoke, <a href="#Page_102">102</a>.<br />
+<br />
+Top-minnows, <a href="#Page_98">98</a>, <a href="#Page_101">101</a>.<br />
+<br />
+Torcel, <a href="#Page_51">51</a>.<br />
+<br />
+Trache&aelig;, <a href="#Page_89">89</a>.<br />
+<br />
+Tracheal gills, <a href="#Page_79">79</a>.<br />
+<br />
+Trichina, <a href="#Page_2">2</a>.<br />
+<br />
+Trypanosome, <a href="#Page_45">45</a>, <a href="#Page_161">161</a>.<br />
+<br />
+Trypanosoma,<br />
+<span style="margin-left: 1em;">evansi, <a href="#Page_45">45</a>;</span><br />
+<span style="margin-left: 1em;">brucei, <a href="#Page_45">45</a>;</span><br />
+<span style="margin-left: 1em;">lewisi, <a href="#Page_162">162</a>;</span><br />
+<span style="margin-left: 1em;">gambiensi, <a href="#Page_162">162</a>.</span><br />
+<br />
+Tsetse-fly, <a href="#Page_45">45</a>, <a href="#Page_163">163</a>.<br />
+<br />
+Tubercular bacilli, <a href="#Page_69">69</a>;<br />
+<span style="margin-left: 1em;">germs, <a href="#Page_69">69</a>.</span><br />
+<br />
+Typhoid-fly, <a href="#Page_57">57</a>, <a href="#Page_59">59</a>.<br />
+<br />
+<br />
+Vaughan, Dr. W.C., <a href="#Page_67">67</a>.<br />
+<br />
+Ver macque, <a href="#Page_51">51</a>.<br />
+<br />
+Verjbitski, D.T., <a href="#Page_147">147</a>.<br />
+<br />
+Vorticella, <a href="#Page_22">22</a>.<br />
+<br />
+<br />
+Water-boatmen, <a href="#Page_100">100</a>.<br />
+<br />
+Water-troughs, <a href="#Page_104">104</a>.<br />
+<br />
+Whip-bearers, <a href="#Page_20">20</a>.<br />
+<br />
+Whirligig beetles, <a href="#Page_100">100</a>.<br />
+<br />
+White, Surgeon J.H., <a href="#Page_134">134</a>.<br />
+<br />
+Wrigglers, <a href="#Page_78">78</a>.<br />
+<br />
+<br />
+Yellow fever, <a href="#Page_120">120</a>;<br />
+<span style="margin-left: 1em;">Commission, <a href="#Page_123">123</a>;</span><br />
+<span style="margin-left: 1em;">early observations on, <a href="#Page_121">121</a>;</span><br />
+<span style="margin-left: 1em;">experiments, <a href="#Page_125">125</a>;</span><br />
+<span style="margin-left: 1em;">danger of in Pacific Islands, <a href="#Page_140">140</a>;</span><br />
+<span style="margin-left: 1em;">in Havana, results of work on, <a href="#Page_131">131</a>;</span><br />
+<span style="margin-left: 1em;">history of in United States, <a href="#Page_120">120</a>;</span><br />
+<span style="margin-left: 1em;">mosquito, <a href="#Page_94">94</a>;</span><br />
+<span style="margin-left: 1em;">habits of, <a href="#Page_95">95</a>;</span><br />
+<span style="margin-left: 1em;">in Panama Canal zone, <a href="#Page_135">135</a>;</span><br />
+<span style="margin-left: 1em;">in Rio de Janeiro, <a href="#Page_137">137</a>;</span><br />
+<span style="margin-left: 1em;">summary of results of work on, <a href="#Page_129">129</a>.</span><br />
+</p>
+
+
+
+
+
+
+
+<pre>
+
+
+
+
+
+End of the Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
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+</body>
+</html>
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+The Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
+
+This eBook is for the use of anyone anywhere at no cost and with
+almost no restrictions whatsoever.  You may copy it, give it away or
+re-use it under the terms of the Project Gutenberg License included
+with this eBook or online at www.gutenberg.org
+
+
+Title: Insects and Diseases
+       A Popular Account of the Way in Which Insects may Spread
+       or Cause some of our Common Diseases
+
+Author: Rennie W. Doane
+
+Release Date: February 24, 2009 [EBook #28177]
+Last updated: March 2, 2009
+
+Language: English
+
+Character set encoding: ASCII
+
+*** START OF THIS PROJECT GUTENBERG EBOOK INSECTS AND DISEASES ***
+
+
+
+
+Produced by Chris Curnow, Lindy Walsh, Greg Bergquist and
+the Online Distributed Proofreading Team at
+http://www.pgdp.net
+
+
+
+
+
+
+  Transcriber's Note
+
+  The punctuation and spelling from the original text have been faithfully
+  preserved. Only obvious typographical errors have been corrected.
+
+
+[Illustration: An artificial lake, nearly dry and partly filled with
+rubbish, has become a breeding-ground for dangerous mosquitoes.]
+
+
+
+
+ American Nature Series
+
+ Group IV. Working with Nature
+
+
+ INSECTS AND DISEASE
+
+ A POPULAR ACCOUNT OF THE WAY IN WHICH
+ INSECTS MAY SPREAD OR CAUSE SOME
+ OF OUR COMMON DISEASES
+
+ WITH MANY ORIGINAL ILLUSTRATIONS FROM
+ PHOTOGRAPHS
+
+
+ BY
+
+ RENNIE W. DOANE, A.B.
+
+ _Assistant Professor of Entomology
+ Leland Stanford Junior University_
+
+
+ LONDON
+
+ CONSTABLE & COMPANY LIMITED
+
+ 1910
+
+ COPYRIGHT, 1910,
+
+ BY
+
+ HENRY HOLT AND COMPANY
+
+
+ _Published August, 1910_
+
+
+ THE QUINN & BODEN CO. PRESS
+
+ RAHWAY, N.J.
+
+
+
+
+PREFACE
+
+
+The subject of preventive medicine is one that is attracting world-wide
+attention to-day. We can hardly pick up a newspaper or magazine without
+seeing the subject discussed in some of its phases, and during the last
+few years several books have appeared devoted wholly or in part to the
+ways of preventing rather than curing many of our ills.
+
+Looking over the titles of these articles and books the reader will at
+once be impressed with the importance that is being given to the subject
+of the relation of insects to some of our common diseases. As many of
+these maladies are caused by minute parasites or microbes the
+zooelogists, biologists and physicians are studying with untiring zeal to
+learn what they can in regard to the development and habits of these
+organisms, and the entomologists are doing their part by studying in
+minute detail the structure and life-history of the insects that are
+concerned. Thus many important facts are being learned, many important
+observations made. The results of the best of these investigations are
+always published in technical magazines or papers that are usually
+accessible only to the specialist.
+
+This little book is an attempt to bring together and place in
+untechnical form the most important of these facts gathered from sources
+many of which are at present inaccessible to the general reader, perhaps
+even to many physicians and entomologists.
+
+In order that the reader who is not a specialist in medicine or
+entomology may more readily understand the intimate biological relations
+of the animals and parasites to be discussed it seems desirable to call
+attention first to their systematic relations and to review some of the
+important general facts in regard to their structure and life-history.
+This, it is believed, will make even the most complex special
+interrelations of some of these organisms readily understandable by all.
+Those who are already more or less familiar with these things may find
+the bibliography of use for more extended reading.
+
+My thanks are due to Prof. V.L. Kellogg for reading the manuscript and
+offering helpful suggestions and criticisms.
+
+Unless otherwise credited the pictures are from photographs taken by the
+author in the laboratory and field. As many of these are pictures of
+live specimens it is believed that they will be of interest as showing
+the insects, not as we think they should be, but as they actually are.
+Mr. J.H. Paine has given me valuable aid in preparing these photographs.
+
+ R.W.D.
+
+ Stanford University, California,
+
+ March, 1910.
+
+
+
+
+CONTENTS
+
+CHAPTER I
+                                                        PAGE
+
+PARASITISM AND DISEASE                                     1
+
+Definition of a parasite, 1; examples among various animals,
+2; _Parasitism_, 3; effect on the parasite, 4; how a harmless
+kind may become harmful, 5; immunity, 6; _Diseases caused by
+parasites_, 7; ancient and modern views, 7; _Infectious and contagious
+diseases_, 8; examples, 9; importance of distinguishing,
+9; _Effect of the parasite on the host_, 9; microbes everywhere, 10;
+importance of size, 11; numbers, 11; location, 11; mechanical
+injury, 12; morphological injury, 13; physiological effect, 13;
+the point of view, 14.
+
+
+CHAPTER II
+
+BACTERIA AND PROTOZOA                                     15
+
+_Bacteria_, 15; border line between plants and animals, 15;
+most bacteria not harmful, 15; a few cause disease, 15; how
+they multiply, 15; parasitic and non-parasitic kinds, 17; how a
+kind normally harmless may become harmful, 18; effect of the
+bacteria on the host, 18; methods of dissemination, 18; _Protozoa_,
+19; _Amoeba_, 19; its lack of special organs, 19; where
+it lives, 19; growth and reproduction, 19; _Classes of Protozoa_,
+20; the amoeba-like forms, 20; the flagellate forms, 20; importance
+of these, 21; the ciliated forms, 22; the Sporozoa or spore-forming kinds,
+22; these most important, 23; abundance, 23; adaptability, 23; common
+characters, 24; ability to resist unfavorable conditions, 24.
+
+
+CHAPTER III
+
+TICKS AND MITES                                           26
+
+_Ticks_, 26; general characters, 27; mouth-parts, 27; habits,
+27; life-history, 27; _Ticks and disease_, 28; _Texas fever_, 28; its
+occurrence in the north, 28; carried by a tick, 29; loss and
+methods of control, 31; other diseases of cattle carried by ticks,
+31; _Rocky Mountain spotted fever_, 32; its occurrence, 32;
+probably caused by parasites, 32; relation of ticks to this disease,
+33; _Relapsing Fever_, 33; its occurrence, 34; transmitted
+by ticks, 34; _Mites_, 35; _Face-mites_, 35; _Itch-mites_, 36;
+_Harvest-mites_, 37.
+
+
+CHAPTER IV
+
+HOW INSECTS CAUSE OR CARRY DISEASE                        40
+
+Numbers, 40; importance, 41; losses caused by insects, 41;
+loss of life, 42; _The flies_, 43; horse-flies, 43; stable-flies, 44;
+surra, 45; nagana, 45; black-flies, 46; punkies, 46; screw-worm
+flies, 47; blow-flies, 48; flesh-flies, 48; fly larvae in intestinal
+canal, 49; bot-flies, 50; _Fleas_, 52; jigger-flea, 53; _Bedbugs_, 54;
+_Lice_, 54; _How insects may carry disease_, 55; in a mechanical
+way, 55; as one of the necessary hosts of the parasite, 56.
+
+
+CHAPTER V
+
+HOUSE-FLIES OR TYPHOID-FLIES                              57
+
+The old attitude toward the house-fly, 57; its present standing,
+58; reasons for the change, 58; _Structure_, 59; head and
+mouth-parts, 60; thorax and wings, 61; feet, 62; _How they
+carry bacteria_, 62; _Life-history_, 63; eggs, 63; ordinarily laid in
+manure, 63; other places, 63; habits of the larvae, 64; habits of
+the adults, 64; places they visit, 65; _Flies and typhoid_, 65;
+patients carrying the germs before and after they have had the
+disease, 65; how the flies get these on their body and distribute
+them, 66; results of some observations and experiments, 66;
+_Flies and other diseases_, 68; flies and cholera, 68; flies and
+tuberculosis, 69; possibility of their carrying other diseases, 70;
+_Fighting flies_, 71; screens not sufficient, 71; the larger problem,
+71; the manure pile, 72; outdoor privies, 72; garbage can,
+72; cooeperation necessary, 72; city ordinances, 73; an expert's
+opinion of the house-fly, 73; _Other flies_, 75; habits of several
+much the same but do not enter house as much, 75; the small
+house-fly, 75; stable-flies, 75; these may spread disease, 75.
+
+
+CHAPTER VI
+
+MOSQUITOES                                                76
+
+Numbers, 76; interest and importance, 76; eggs, 77; always in water, 77;
+time of hatching, 77; _Larvae_, 78; live only in water, 78; head and
+mouth-parts of larvae, 78; what they feed on, 78; breathing apparatus,
+79; growth of the larvae, 80; _Pupae_, 80; active but takes no food, 80;
+breathing tubes, 80; how the adult issues, 81; _The Adult_, 81; male and
+female, 81; how mosquitoes "sing" and how the song is heard, 82; the
+palpi, 82; _The Mouth-parts_, 83; needles for piercing, 83; _How the
+mosquito bites_, 84; secretion from the salivary gland, 84; why males
+cannot bite, 84; blood not necessary for either sex, 84; _The Thorax_,
+85; the legs, 85; the wings, 85; the balancers, 85; the breathing pores,
+86; _The abdomen_, 86; _The digestive system_, 86; _The salivary
+glands_, 87; their importance, 87; effects of a mosquito bite, 87;
+probable function of the saliva, 88; _How mosquitoes breathe_, 89;
+_Blood_, 90; in body cavity, 90; heart, 90; _Classification_, 91;
+_Anopheles_, 91; distinguishing characters, 92; eggs, 92; where the
+larvae are found, 93; _Yellow fever mosquito_, 94; its importance, 94;
+the adult, 95; habits, 95; habits of the larvae, 95; _Other species_, 96;
+some in fresh water, others in brackish water, 96; Natural enemies of
+mosquitoes, 97; how natural enemies of mosquitoes control their numbers,
+98; mosquitoes in Hawaii, 98; _Enemies of the adults_, 99; _Enemies of
+the larvae and pupae_, 100; _Fighting mosquitoes_, 101; fighting the
+adult, 102; _Fighting the larvae_, 103; domestic or local species, 104;
+draining and treating with oil, 104; combatting salt-marsh species by
+draining, 105; by minnows or oil, 105.
+
+
+CHAPTER VII
+
+MOSQUITOES AND MALARIA                                   106
+
+Early reference to malaria, 106; its general distribution, 106;
+theories in regard to its cause, 107; insects early suspected, 107;
+_The parasite that causes malaria_, 108; studies of the parasite,
+108; _Life-history in human host_, 109; its effect on the host, 110;
+the search for the sexual generation, 111; _The parasite in the
+mosquito_, 112; review of whole life-history, 115; malaria transmitted
+only by mosquitoes, 115; _Summary_, 117; experimental proof, 118.
+
+
+CHAPTER VIII
+
+MOSQUITOES AND YELLOW FEVER                              120
+
+A disease of tropical or semi-tropical countries, 120; outbreaks in the
+United States, 120; parasite that causes the disease not known, 121;
+formerly regarded as a contagious disease, 122; _The yellow fever
+commission_, 123; Dr. Finlay's claim, 124; experiments made by the
+commission, 125; summary of results, 129; what it means, 130; _results
+in Havana_, 131; _the fight in New Orleans_, 132; _In the Panama canal
+zone_, 135; _in Rio de Janeiro_, 136; claims of the French commission,
+138; _habits of stegomyia_, 139; breeding habits, 139; possible results
+of war against the mosquitoes, 139; Danger of this disease in the
+Pacific Islands, 140.
+
+
+CHAPTER IX
+
+FLEAS AND PLAGUE                                         142
+
+Great scourges, 142; the "black death," 142; old conditions
+and new, 143; _How plague was controlled in San Francisco_,
+143; _Indian Plague commission_, 144; Dr. Simond's claim,
+145; The advisory committee and the new commission, 146;
+_Results of Dr. Verjbitski's experiments_, 147; _Results of various
+investigations_, 150; _structure and habits of fleas_, 151; feeding
+habits, 152; _Common species of fleas_, 153; _Ground squirrels and
+plague_, 155; squirrel fleas, 156; _Remedies for fleas_, 157; cats
+and dogs, 159.
+
+
+CHAPTER X
+
+OTHER DISEASES, MOSTLY TROPICAL, KNOWN OR THOUGHT TO
+BE TRANSMITTED BY INSECTS                                161
+
+_Sleeping Sickness_, 161; its occurrence in Africa, 161; caused by a
+Protozoan parasite, 162; the tsetse-fly, 163; _Elephantiasis_, 164;
+caused by parasitic worms, 164; their development, 165; how they are
+transferred to man, 165; effect on the patient, 166; _Dengue_, 168;
+other names, 168; probably transmitted by mosquitoes, 170;
+_Mediterranean fever_, 171; cause, 171; may be conveyed by mosquitoes,
+171; _Leprosy_, 171; caused by a bacteria parasite, 171; possibilities
+of flies, mosquitoes and other insects transmitting the disease, 172;
+_Kala-azar_, 173; transmitted by the bedbug, 173; _Oriental sore_, 174;
+the parasite may be carried by insects, 174.
+
+BIBLIOGRAPHY                                             175
+
+Parasites and parasitism, 175; Protozoa, 176; Bacteria, 177; Insects and
+disease, 178; Mosquitoes--systematic and general, 179; Mosquito anatomy,
+182; Mosquitoes--life-history and habits, 183; Mosquito fighting, 183;
+Mosquitoes and disease, 185; Malaria, 186; Yellow fever, 189; Dengue,
+192; Filarial diseases and elephantiasis, 193; Leprosy, 193; Plague,
+194; Fleas, 198; Typhoid fever, 199; House-flies--anatomy, life-history,
+habits, 200; House-flies and typhoid, 202; House-fly and various
+diseases, 203; Human myiasis, 207; Stomoxys and other flies, 208;
+tsetse-flies, 209; Trypanosomes and Trypanosomiasis, 210; Sleeping
+sickness, 211; Rocky mountain fever and ticks, 212; Ticks and various
+diseases, 213; Kala-azar and bedbugs, 216; Text or reference books, 216;
+Miscellaneous articles, 218.
+
+
+
+
+ILLUSTRATIONS
+
+ AN ARTIFICIAL LAKE, NEARLY DRY AND PARTLY
+ FILLED WITH RUBBISH, HAS BECOME A BREEDING-GROUND
+ FOR DANGEROUS MOSQUITOES                                 _Frontispiece_
+
+                                                                    PAGE
+
+ FIG. 1. A LAMPREY                                                     2
+
+ FIG. 2. _Sacculina_                                                   2
+
+ FIG. 3. _Trichina spiralis_                                           2
+
+ FIG. 4. AN EXTERNAL PARASITE, A BIRD-LOUSE (_Lipeurus
+   ferox_)                                                             3
+
+ FIG. 5. AN INTERNAL PARASITE, A TACHINA FLY (_Blepharipeza
+   adusta_)                                                            3
+
+ FIG. 6. WORK OF AN INTERNAL PARASITE, PUSS-MOTH LARVA
+   PARASITIZED BY A SMALL ICHNEUMON FLY                                3
+
+ FIG. 7. TYPHOID FEVER BACILLI                                        20
+
+ FIG. 8. _Amoeba_                                                     20
+
+ FIG. 9. _Euglina virdis_                                             21
+
+ FIG. 10. _Spirocheta duttoni_                                        21
+
+ FIG. 11. _Paramoecium_                                               22
+
+ FIG. 12. _Vorticella_                                                22
+
+ FIG. 13. PATHOGENIC PROTOZOA; A GROUP OF INTESTINAL
+   PARASITES                                                          22
+
+ FIG. 14. CASTOR-BEAN TICK (_Ixodes ricinus_)                         28
+
+ FIG. 15. TEXAS FEVER TICK                                            28
+
+ FIG. 16. TEXAS FEVER TICK (_Margaropus annulatus_)                   29
+
+ FIG. 17. _Amblyomma variegatum_                                      29
+
+ FIG. 18. _Ornithodoros moubata_                                      36
+
+ FIG. 19. THE FOLLICLE MITE (_Demodex folliculorum_)                  36
+
+ FIG. 20. ITCH-MITE (_Sarcoptes scabiei_)                             37
+
+ FIG. 21. HARVEST-MITES OR "JIGGERS"                                  37
+
+ FIG. 22. HORSE-FLY (_Tabanus punctifer_)                             44
+
+ FIG. 23. STABLE-FLY (_Stomoxys calcitrans_)                          44
+
+ FIG. 24. A BLACK-FLY (_Simulium sp._)                                45
+
+ FIG. 25. SCREW-WORM FLY (_Chrysomyia macellaria_)                    45
+
+ FIG. 26. BLOW-FLY (_Calliphora vomitoria_)                           45
+
+ FIG. 27. BLUE-BOTTLE FLY (_Lucilia sericata_)                        50
+
+ FIG. 28. FLESH-FLY (_Sarcophaga sp._)                                50
+
+ FIG. 29. "THE LITTLE HOUSE-FLY" (_Homalomyia canicularis_)           51
+
+ FIG. 30. HORSE BOT-FLY (_Gastrophilus equi._)                        51
+
+ FIG. 31. OXWARBLE FLY (_Hypoderma lineata_)                          51
+
+ FIG. 32. SHEEP BOT-FLY (_Gastrophilus nasalis_)                      51
+
+ FIG. 33. CHIGO OR JIGGER-FLEA, MALE (_Dermatophilus penetrans_)      54
+
+ FIG. 34. CHIGO, FEMALE DISTENDED WITH EGGS                           54
+
+ FIG. 35. BEDBUG (_Cimex lectularis_)                                 55
+
+ FIG. 36. BODY-LOUSE (_Pediculus vestimenti_)                         55
+
+ FIG. 37. ONE USE FOR THE HOUSE-FLY                                   57
+
+ FIG. 38. THE HOUSE-FLY (_Musca domestica_)                           58
+
+ FIG. 39. HEAD OF HOUSE-FLY SHOWING EYES, ANTENNAE AND
+   MOUTH-PARTS                                                        60
+
+ FIG. 40. PROBOSCIS OF HOUSE-FLY, SIDE VIEW                           60
+
+ FIG. 41. LOBES AT END OF PROBOSCIS OF HOUSE-FLY SHOWING
+   CORRUGATED RIDGES                                                  61
+
+ FIG. 42. WING OF HOUSE-FLY                                           61
+
+ FIG. 43. WING OF STABLE-FLY (_Stomoxys calcitrans_)                  62
+
+ FIG. 44. WING OF HOUSE-FLY SHOWING PARTICLES OF DIRT
+   ADHERING TO IT                                                     62
+
+ FIG. 45. LAST THREE SEGMENTS OF LEG OF HOUSE-FLY                     62
+
+ FIG. 46. FOOT OF HOUSE-FLY                                           63
+
+ FIG. 47. LARVA OF HOUSE-FLY                                          63
+
+ FIG. 48. BARN-YARD FILLED WITH MANURE                                64
+
+ FIG. 49. DIRTY STALLS                                                65
+
+ FIG. 50. PUPA OF HOUSE-FLY                                           76
+
+ FIG. 51. HEAD OF STABLE-FLY                                          76
+
+ FIG. 52. MASS OF MOSQUITO EGGS (_Theobaldia incidens_)               76
+
+ FIG. 53. MOSQUITO EGGS AND LARVAE (_T. incidens_)                     77
+
+ FIG. 54. MOSQUITO LARVA (_T. incidens_), DORSAL VIEW                 77
+
+ FIG. 55. EGGS, LARVAE AND PUPAE OF MOSQUITOES (_T. incidens_)          78
+
+ FIG. 56. LARVA OF MOSQUITO (_T. incidens_)                           78
+
+ FIG. 57. MOSQUITO LARVAE AND PUPAE (_T. incidens_)                     79
+
+ FIG. 58. ANOPHELES LARVAE (_A. maculipennis_)                         79
+
+ FIG. 59. MOSQUITO PUPAE (_T. incidens_)                               80
+
+ FIG. 60. MOSQUITO PUPA (_T. incidens_)                               80
+
+ FIG. 61. MOSQUITO LARVAE AND PUPAE (_T. incidens_)                     80
+
+ FIG. 62. A FEMALE MOSQUITO (_T. incidens_)                           81
+
+ FIG. 63. A MALE MOSQUITO (_T. incidens_)                             81
+
+ FIG. 64. HEAD AND THORAX OF FEMALE MOSQUITO (_Ochlerotatus
+   lativittatus_)                                                     82
+
+ FIG. 65. HEAD AND THORAX OF MALE MOSQUITO (_O. lativittatus_)        82
+
+ FIG. 66. HEAD OF FEMALE MOSQUITO                                     83
+
+ FIG. 67. CROSS-SECTION OF PROBOSCIS OF FEMALE AND MALE
+   MOSQUITO                                                           83
+
+ FIG. 68. WING OF MOSQUITO (_O. lativittatus_)                        86
+
+ FIG. 69. END OF MOSQUITO WING HIGHLY MAGNIFIED                       86
+
+ FIG. 70. DIAGRAM TO SHOW THE ALIMENTARY CANAL AND
+   SALIVARY GLANDS OF A MOSQUITO                                      87
+
+ FIG. 71. SALIVARY GLANDS OF MOSQUITOES                               87
+
+ FIG. 72. HEADS OF CULICINAE MOSQUITOES                                90
+
+ FIG. 73. HEADS OF ANOPHELINAE MOSQUITOES                              90
+
+ FIG. 74. WING OF _Anopheles maculipennis_                            90
+
+ FIG. 75. WING OF _Theobaldia incidens_                               90
+
+ FIG. 76. A NON-MALARIAL MOSQUITO (_T. Incidens_), MALE,
+   STANDING ON THE WALL                                               91
+
+ FIG. 77. FEMALE OF SAME                                              91
+
+ FIG. 78. A MALARIAL MOSQUITO (_A. maculipennis_), MALE,
+   STANDING ON THE WALL                                               91
+
+ FIG. 79. FEMALE OF SAME                                              91
+
+ FIG. 80. EGG OF _Anopheles_, SIDE VIEW                               92
+
+ FIG. 81. EGG OF ANOPHELES, DORSAL VIEW                               92
+
+ FIG. 82. ANOPHELES LARVAE                                             92
+
+ FIG. 83. ANOPHELES LARVAE                                             93
+
+ FIG. 84. ANOPHELES LARVA, DORSAL VIEW                                93
+
+ FIG. 85. ANOPHELES PUPAE RESTING AT SURFACE OF WATER                  93
+
+ FIG. 86. SALT-MARSH MOSQUITO (_Ochlerotatus lativittatus_);
+   MALE                                                               98
+
+ FIG. 87. SALT-MARSH MOSQUITO (_O. lativittatus_); FEMALE             98
+
+ FIG. 88. TOP-MINNOW (_Mollienisia latipinna_)                        99
+
+ FIG. 89. DRAGON-FLIES                                                99
+
+ FIG. 90. THE YOUNG (NYMPH) OF A DRAGON-FLY                          100
+
+ FIG. 91. THE CAST SKIN (_exuvae_) OF A DRAGON-FLY NYMPH              100
+
+ FIG. 92. DIVING-BEETLES AND BACK-SWIMMERS                           101
+
+ FIG. 93. KILLIFISH (_Fundulus heteroliatus_)                        102
+
+ FIG. 94. STICKLEBACK (_Apeltes quadracus_)                          102
+
+ FIG. 95. AN OLD WATERING-TROUGH, AN EXCELLENT BREEDING-PLACE
+   FOR MOSQUITOES                                                    103
+
+ FIG. 96. HORSE AND CATTLE TRACKS IN MUD FILLED WITH
+   WATER                                                             108
+
+ FIG. 97. A MALARIAL MOSQUITO (_Anopheles maculipennis_)
+   MALE                                                              108
+
+ FIG. 98. A MALARIAL MOSQUITO (_A. maculipennis_) FEMALE             109
+
+ FIG. 99. DIAGRAM TO ILLUSTRATE THE LIFE-HISTORY OF THE
+   MALARIAL PARASITE                                                 110
+
+ FIG. 100. MALARIAL MOSQUITO (_A. maculipennis_) ON THE WALL         111
+
+ FIG. 101. MALARIAL MOSQUITO (_A. maculipennis_) STANDING ON
+   A TABLE                                                           111
+
+ FIG. 102. SALT-MARSH MOSQUITO (_O. lativittatus_) STANDING ON
+   A TABLE                                                           118
+
+ FIG. 103. ANOPHELES HANGING FROM THE CEILING                        118
+
+ FIG. 104. YELLOW FEVER MOSQUITO (_Stegomyia calopus_)               122
+
+ FIG. 105. RAT-FLEA (_Laemopsylla cheopis_); MALE                     152
+
+ FIG. 106. RAT-FLEA (_L. cheopis_); FEMALE                           152
+
+ FIG. 107. HEAD OF RAT-FLEA SHOWING MOUTH-PARTS                      153
+
+ FIG. 108. HUMAN-FLEA (_Pulex irritans_); MALE                       153
+
+ FIG. 109. HUMAN-FLEA (_P. irritans_); FEMALE                        156
+
+ FIG. 110. MOUSE-FLEA (_Ctenopsyllus musculi_); FEMALE               156
+
+ FIG. 111. TRYPANOSOMA GAMBIENSE                                     164
+
+ FIG. 112. TSETSE-FLY                                                164
+
+
+
+
+INSECTS AND DISEASE
+
+
+
+
+CHAPTER I
+
+PARASITISM AND DISEASE
+
+
+PARASITES
+
+The dictionary says that a parasite is a living organism, either animal
+or plant, that lives in or on some other organism from which it derives
+its nourishment for a whole or part of its existence. This definition
+will serve as well as any, as it seems to include all the forms that
+might be classed as parasites. As a general thing, however, we are
+accustomed to think of a parasite as working more or less injury to its
+host, or perhaps we had better say that if it does not cause any
+irritation or ill effects its presence is not noted and we do not think
+of it at all.
+
+As a matter of fact the number of parasitic organisms that are actually
+detrimental to the welfare of their hosts is comparatively small while
+the number of forms both large and small that lead parasitic lives in
+or on various hosts, usually doing no appreciable harm, often perhaps
+without the host being aware of their presence, is very great indeed.
+
+Few of the higher animals live parasitic lives. The nearest approach to
+a true parasite among the vertebrates is the lamprey-eel (Fig. 1) which
+attaches itself to the body of a fish and sucks the blood or eats the
+flesh. Among the Crustaceans, the group that includes the lobsters and
+crabs, we find many examples of parasites, the most extraordinary of
+which is the curious crab known as _Sacculina_ (Fig. 2). In its early
+stages this creature is free-swimming and looks not unlike other young
+crabs. But it soon attaches itself to another crab and begins to live at
+the expense of its host. Then it commences to undergo remarkable changes
+and finally becomes a mere sac-like organ with a number of long slender
+root-like processes penetrating and taking nourishment from the body of
+the unfortunate crab-host.
+
+The worms furnish many well-known examples of parasites, whole groups of
+them being especially adapted to parasitic life. The tapeworms, common
+in many animals and often occurring in man, the roundworms of which the
+trichina (Fig. 3) that causes "measly" pork is a representative, are
+familiar examples. These and a host of others all show a very high
+degree of specialization fitting them for their peculiar lives in their
+hosts.
+
+[Illustration: FIG. 1--A lamprey. (After Goode.)]
+
+[Illustration: FIG. 2--_Sacculina_; _A_, parasite attached to a crab;
+_B_, the active larval condition; _C_, the adult removed from its host.
+(After Haeckel.)]
+
+[Illustration: FIG. 3--_Trichina spiralis_ encysted in muscle of a pig.
+(From Kellogg's Elementary Zooel.)]
+
+[Illustration: FIG. 4--An external parasite, a bird-louse (_Lipeurus
+ferox_).]
+
+[Illustration: FIG. 5--A tachina fly (_Blepharipeza adusta_) the larva
+of which is an internal parasite.]
+
+[Illustration: FIG. 6--Work of an internal parasite, puss-moth larva
+parasitized by a small ichneumon fly.]
+
+From among the insects may be selected interesting examples of almost
+all kinds and degrees of parasitism, temporary, permanent, external,
+internal (Figs. 4, 5, 6). Among them is found, too, that curious
+condition known as hyperparasitism where one animal, itself a parasite,
+is preyed upon by a still smaller parasite.
+
+  "The larger fleas have smaller fleas
+  Upon their backs to bite um,
+  These little fleas still smaller fleas
+  And so _ad infinitum_."
+
+Coming now to the minute, microscopic, one-celled animals, the Protozoa,
+we find entire groups of them that are living parasitic lives, depending
+wholly on one or more hosts for their existence. Many of these have a
+very remarkable life-history, living part of the time in one host, part
+in another. The malarial parasite and others that cause some of the
+diseases of man and domestic animals are among the most important of
+these.
+
+
+PARASITISM
+
+Among all these parasites, from the highest to the lowest the process
+that has fitted them for a parasitic life has been one of degeneration.
+While they may be specialized to an extreme degree in one direction they
+are usually found to have some of the parts or organs, which in closely
+related forms are well developed, atrophied or entirely wanting. As a
+rule this is a distinct advantage rather than a disadvantage to the
+parasite, for those parts or organs that are lost would be useless or
+even in the way in its special mode of life.
+
+Then, too, the parasite often gives up all its independence and becomes
+wholly dependent on its host or hosts not only for its food but for its
+dissemination from one animal to another, in order that the species may
+not perish with the host. But in return for all this it has gained a
+life of ease, free from most of the dangers that beset the more
+independent animals, and is thus able to devote its whole time and
+energy to development and the propagation of the species.
+
+We are accustomed to group the parasites that we know into two classes,
+as harmful or injurious and as harmless, the latter including all those
+kinds that do not ordinarily affect our well-being in any way. But such
+a classification is not always satisfactory or safe, for certain
+organisms that to-day or under present conditions are not harmful may,
+on account of a great increase in numbers or change of conditions,
+become of prime importance to-morrow. An animal that is well and strong
+may harbor large numbers of parasites which are living at the expense of
+some of the host's food or energy or comfort, yet the loss is so small
+that it is not noticed and the intruders, if they are thought of at all,
+are classed as harmless. Or we may at times even look upon them as
+beneficial in one way or another. "A reasonable amount of fleas is good
+for a dog. They keep him from brooding on being a dog."
+
+But should these parasites for some reason or other increase rapidly
+they might work great harm to the host. Even David Harum would limit the
+number of fleas on a dog. Or the animal might become weakened from some
+cause so that the drain on its resources made by the parasites, even
+though they did not increase in numbers, would materially affect it.
+
+Perhaps the most serious way in which parasites that are usually
+harmless may become of great importance is illustrated by their
+introduction into new regions or, as is more often the case, by the
+introduction of new hosts into the region where the parasites are found.
+Under normal conditions the animals of a given region are usually immune
+to the parasites of the same region. That is, they actually repel them
+and do not suffer them to exist in or on their bodies, or they are
+tolerant toward them. In the latter case the parasites live at the
+expense of the host, but the host has become used to their being there,
+adapted to them, and the injury that they do, if any, is negligible.
+
+But when a new animal comes into the region from some other locality the
+parasites may be extremely dangerous to it. There are many striking
+examples of this. Most of the people living in what is known as the
+yellow fever belt are immune to the fever. They will not develop it even
+under conditions that would surely mean infection for a person from
+outside this zone. Certain of our common diseases which we regard as of
+little consequence become very serious matters when introduced among a
+people that has never known them before. The cattle of the southern
+states are immune to the Texas fever, but let northern cattle be sent
+south or let the ticks which transmit the disease be taken north where
+they can get on cattle there, and the results are disastrous.
+
+Another striking example and one that is attracting world-wide attention
+just now is the trypanosome that is causing such devastation among the
+inhabitants of central Africa. With the advent of white men into this
+region and the consequent migration of the natives along the trade
+routes this parasite, which is the cause of sleeping sickness, is being
+introduced into new regions and thousands upon thousands of people are
+dying as a result of its ravages.
+
+
+DISEASES CAUSED BY PARASITES
+
+Some two hundred years ago, after it became known that minute animal
+parasites were associated with certain diseases and were the cause of
+them, it rapidly came to be believed that all our ills were in some way
+caused by such parasites, known or unknown. Further study and
+investigation failed to reveal the intruders in many instances and so it
+began to be doubted whether after all they were responsible for much
+that had been laid at their doors. Then after it was discovered that
+minute plant parasites, bacteria, were responsible for many diseases
+they in turn began to be accused of being the cause of most of the ills
+that the flesh is heir to.
+
+In later years we have come to adopt what seems to be a more reasonable
+view, for we can see and definitely prove that neither of these extreme
+views was correct but that there was much truth in each of them. To-day
+we recognize that certain diseases, such as typhoid, cholera,
+tuberculosis and many others, are caused by the presence of bacteria in
+the body, and it is just as definitely known that such maladies as
+malaria and sleeping sickness are caused by animal parasites.
+
+Then there is a long list of other epidemic diseases, such as smallpox,
+measles and scarlet fever, the exact cause of which has not been
+determined. Many of these are believed to be due to micro-organisms of
+some kind, and if so they will almost certainly sooner or later be
+found. Curiously enough most of the diseases in this last class and many
+of those in the first are contagious, while all that are caused by
+animal parasites are, as far as is known, infectious but not contagious.
+
+
+INFECTIOUS AND CONTAGIOUS DISEASES
+
+It is important that we keep in mind this distinction. By contagious
+diseases are meant those that are transmitted by contact with the
+diseased person either directly, by touch, or indirectly by the use of
+the same articles, by the breath or effluvial emanations from the body
+or other sources. Small-pox, measles, influenza, etc., are examples of
+this group. By infectious diseases are meant those which are
+disseminated indirectly, that is, in a roundabout way by means of water
+or food or other substances taken into or introduced into the body in
+some way. Typhoid, malaria, and yellow fever, cholera and others are
+examples of this class. Thus it is evident that all of the contagious
+diseases may be infectious, but many of the infectious diseases are not
+as a rule contagious, although some of them may become so under
+favorable conditions.
+
+Just one example will show the importance of knowing whether a disease
+is contagious or infectious. Until a few years ago it was believed that
+yellow fever was highly contagious and every precaution was taken to
+keep the disease from spreading by keeping the infected region in strict
+quarantine. This often meant much hardship and suffering and always a
+great financial loss. We now know that it is infectious only and not
+contagious, and that all this quarantine was unnecessary. The whole
+fight in controlling an outbreak of yellow fever or in preventing such
+an outbreak is now directed against the mosquito, the sole agent by
+which the disease can be transmitted from one person to another.
+
+
+EFFECT OF THE PARASITE ON THE HOST
+
+We have seen how a few parasites in or on an animal do not as a rule
+produce any appreciable ill effects. This is of course a most fortunate
+thing for us, for the parasitic germs are everywhere.
+
+There is perhaps "more truth than poetry" in the following newspaper
+jingle:
+
+  "Sing a song of microbes,
+    Dainty little things,
+  Eyes and ears and horns and tails,
+    Claws and fangs and stings.
+  Microbes in the carpet,
+    Microbes in the wall,
+  Microbes in the vestibule,
+    Microbes in the hall.
+  Microbes on my money,
+    Microbes in my hair,
+  Microbes on my meat and bread,
+    Microbes everywhere.
+  Microbes in the butter,
+    Microbes in the cheese,
+  Microbes on the knives and forks,
+    Microbes in the breeze.
+  Friends are little microbes,
+    Enemies are big,
+  Life among the microbes is--
+    Nothing '_infra dig_.'
+  Fussy little microbes,
+    Millions at a birth,
+  Make our flesh and blood and bones,
+    Keep us on the earth."
+
+While of course most of these microbes are to be regarded as absolutely
+harmless and some as very useful, many have the power to do much injury
+if the proper conditions for their rapid development should at any time
+exist. While the size of the parasite is always a factor in the damage
+that it may do to the host the factor of numbers is perhaps of still
+greater importance because of the power of very rapid multiplication
+possessed by so many of the smaller forms.
+
+Certain minute parasites in the blood may cause little or no
+inconvenience, but should they begin to multiply too rapidly some of the
+capillaries may be filled up and trouble thus result. Or take some of
+the larger forms. A few intestinal worms may cause no appreciable effect
+on the host, but as soon as their numbers increase serious conditions
+may come about simply by the presence of the great masses in the host
+even if they were not robbing it of its nourishment. Many instances are
+known where such worms have formed masses that completely clogged up the
+alimentary canal. Such injuries as these may be regarded as mechanical
+injuries. Some parasites injure the host only when they are laying their
+eggs or reproducing the young. These may clog up passages or some of
+them may be carried to some more sensitive part of the body where the
+damage is done. The guinea-worm of southwestern Asia and of Africa lives
+in the body of its host for nearly a year sometimes attaining a great
+length and migrating through the connective tissue to different parts of
+the body causing no particular inconvenience until it is ready to lay
+its eggs when it comes to the surface and then great suffering may
+result. The African eye-worm is another example of a parasite causing
+mechanical injury only at certain times. It works in the tissues of the
+body sometimes for a long while, doing no harm unless it finds its way
+to the connective tissue of the eyeball.
+
+It is known that many of the germs which cause diseases cannot get into
+the body unless the protecting membranes have first been injured in some
+way. Thus the germs that cause plague and lockjaw find their way into
+the system principally through abrasions of the skin. Many physicians
+have come to believe that the typhoid fever germ cannot get into the
+body from the intestine where it is taken with our food or drink unless
+the walls of the intestine have been injured in some way. It is well
+known that of the many parasites that inhabit the alimentary canal some
+rasp the surface and others bore through into the body cavity. This in
+itself may not be a serious thing, but if the mechanical injury thus
+caused opens the way for malignant germs, baneful results may follow.
+Even that popular disease appendicitis is believed to be due sometimes
+to the injury caused by the work of parasites in the appendix.
+
+Parasites may cause morphological or structural changes in the tissues
+of their hosts. The stimulation caused by their presence may result in
+swellings or excresences or other abnormal growths. Interesting examples
+of this are to be found in the way in which pearls are formed in various
+mollusks. In the pearl oysters of Ceylon occur some of the best pearls.
+If these are carefully sectioned there may usually be found at the
+center the remains of certain cestode larvae whose presence in the oyster
+caused it to deposit the nacreous layers that make up the pearl. Other
+parasites cause similar growths in various shellfish. The great
+enlargements of the arms or legs or other parts of the body seen in
+patients affected with elephantiasis is an abnormal growth due to the
+presence of the parasitic filarae in some of the lymph-glands where they
+have come to rest.
+
+Finally, the parasite may exert a direct physiological effect on the
+host. This is evident when the parasite demands and takes a portion of
+the nourishment that would otherwise go to the building up of the host.
+Sometimes this is of little importance, but at other times it may be a
+matter of life or death to the infected animal. The physiological
+effect produced may be due to the toxins or poisonous matters that are
+given off by the parasite while it is living in the host's body. Thus it
+is believed that the malarial patients usually suffer less from the
+actual loss of red blood-corpuscles that are destroyed by the parasite
+than they do from the effects of the poisonous excretions that are
+poured into the circulation when the thousands of corpuscles break to
+release the parasites.
+
+One other point in regard to the relation of the parasite to its host
+and this part of the subject may be dismissed. From our standpoint we
+look upon the presence of parasites in the body as an abnormal
+condition. From a biological standpoint their presence there is
+perfectly normal; it is a necessary part of their life. We think that
+they have no business there, but from the viewpoint of the parasites
+their whole business is to be just there. If they are not, they perish.
+And when we take a dose of quinine or other drug we are killing or
+driving from their homes millions of these little creatures who have
+taken up their abode with us for the time being. But they interfere with
+our health and comfort, so they must go.
+
+
+
+
+CHAPTER II
+
+BACTERIA AND PROTOZOA
+
+
+BACTERIA
+
+On the border line between the plant and the animal worlds are many
+forms which possess some of the characteristics of both. Indeed when an
+attempt is made to separate all known organisms into two groups one is
+immediately confronted with difficulties. In looking over the text-books
+of Botany we will find that certain low forms are discussed there as
+belonging with the plants, and on turning to the manuals of Zooelogy we
+will find that the same organisms are placed among the lowest forms of
+animals. The question is of course of little actual importance from
+certain points of view. It serves, however, to show the close relation
+of all forms of life, and from a medical standpoint it may be of very
+great importance owing to the difference in the life-habits, methods of
+reproduction and methods of transmission of many of the forms that cause
+disease. We have already seen that none of the diseases that are caused
+by animal parasites is contagious, while many of those caused by
+bacteria are both contagious and infectious.
+
+Just over on the plant side of this indefinite border line are the
+minute organisms known as bacteria. Their numbers are infinite and they
+are found everywhere. The majority of them are beneficial to mankind in
+one way or another, but some of them cause certain of the diseases that
+we will have to discuss later so attention may be called here to a few
+of the important facts in regard to their organization and life-history
+in order that we may better understand how they may be so easily
+transferred from one host to another.
+
+Although these bacilli are so extremely minute (Fig. 7), some of them so
+small that they cannot be seen with the most powerful microscopes, they
+differ in size, shape, methods of division and spore-formation. Each
+species makes a characteristic growth on gelatin, agar or other media
+upon which it may be cultivated. In this way as well as by the
+inoculation of animals the presence of the ultramicroscopic kinds may be
+demonstrated.
+
+The method of reproduction is very simple. They increase to a certain
+point in size, then divide. This growth and division takes place very
+rapidly. Twenty to thirty minutes is sufficient time in some cases for
+a just-divided cell to attain full size and divide again. Thus in a few
+days time the number of bacteria resulting from a single individual
+would be inconceivable if they should all develop.
+
+Fortunately for us, however, they do not all multiply so rapidly as this
+and besides there are natural checks, not the least of which are the
+substances given off by the bacteria themselves in their growth and
+development. Such excretions often serve to inhibit further
+multiplication. Sometimes, though not often, they form spores which not
+only provide for a more rapid multiplication, but enable the organism to
+live under conditions that would otherwise prove fatal to it.
+
+Bacteria may be conveniently grouped under two heads: those that live
+upon dead organic matter, known as the saprophytic forms, and those that
+are found in living plants or animals, the true parasites. Such a
+grouping is not always entirely satisfactory, for many of the kinds that
+live saprophytically under normal conditions may become parasitic if
+opportunity offers, and also many of those that are usually regarded as
+parasitic may be grown in cultures of agar or other media, under which
+conditions they may be regarded as living saprophytically.
+
+It is this power of easily adapting themselves to different conditions
+that makes many of the kinds dangerous. The bacillus which causes
+tetanus or lockjaw will illustrate this. It is a rather common bacillus
+in soil in many localities. As long as it remains there it is of no
+special importance, but if it is introduced into the body through a
+scratch or any other wound it becomes a very serious matter.
+
+We may say, then, that the effect the bacillus has on the host depends
+largely on the host. Not only does it depend on what the host is, but
+the particular condition of the host at the time of infection is of
+importance. Children are subject to many diseases that adults seldom
+have. Hunger, thirst, fatigue, exposure and other factors may make a
+person susceptible to the actions of certain bacteria that would be
+harmless under other conditions.
+
+The minute size and great numbers of the bacteria make their
+dissemination a comparatively simple matter. They may be carried in the
+air as minute particles of dust; they may be carried in water or milk;
+they may be carried on the clothing or on the person from one host to
+another, or they may be disseminated in scores of other ways. In other
+chapters, particularly the one dealing with the house-fly and typhoid,
+we shall see how it is that insects are often important factors in
+spreading some of the most dreaded of the bacterial diseases.
+
+
+THE PROTOZOA
+
+The Protozoa, or one-celled animals, belonged to an unknown world before
+the invention of the microscope. The first of these instruments enabled
+the early observers to see some of the larger and more conspicuous
+members of the group and each improvement of the microscope has enabled
+us to see more and more of them and to study in detail not only the
+structure but to follow the life-history of many of them.
+
+_The Amoeba._ With some, as the common amoeba (Fig. 8), a minute
+little form that is to be found in the slime at the bottom of almost any
+body of water, the life-history is extremely simple. The organism itself
+consists of a minute particle of protoplasm, a single cell with no
+definite shape or body-wall and no specialized organs or apparatus for
+carrying on the life-functions. It lives in the slime or ooze in fresh
+or salt water, takes its food by simply flowing over the particle that
+is to be ingested, grows to a certain limit of size, then divides into
+two more or less equal parts, each part becoming a new animal that goes
+on with its development as did the parent form. This process of growth
+and division may go on for many generations, but cannot continue
+indefinitely unless there is a conjugation of two separate individuals.
+This process of conjugation is just the opposite to that of division.
+Two amoeba flow together and become one. It seems to rejuvenate the
+organism so that it is able to go on with its division and thus fulfil
+its life-mission which is the same for these lowly animals as with the
+higher, that of perpetuating the species.
+
+_Classes of Protozoa._ The group or Phylum Protozoa is divided into four
+smaller groups or classes. The amoeba belongs to the lowest of these,
+the Rhizopoda. Rhizopoda means "root-footed," and the name is applied to
+these animals because most of them move about by means of root-like
+processes known as pseudopodia or "false feet." This is by far the
+largest class and contains thousands of forms, mostly living in salt
+water but there are many fresh-water species. They are non-parasitic,
+but some of them by their presence in the body may cause such diseases
+as dysentery, etc.
+
+[Illustration: FIG. 7--Typhoid Fever bacilli. (After Muir and
+Ritchie.)]
+
+[Illustration: FIG. 8--_Amoeba_, showing the forms assumed by a single
+individual in four successive changes. (From Kellogg's Elementary
+Zooel.)]
+
+[Illustration: FIG. 9--_Euglina virdis._ (After Saville Kent.)]
+
+[Illustration: FIG. 10--_Spirocheta duttoni_, x 4500. (After Breinl and
+Carter.)]
+
+The next class which may be known as the whip-bearers (_Mastigophora_)
+includes those Protozoa that move by fine undulating processes called
+flagella. One of the common representatives of this class is the little
+green _Euglena_ (Fig. 9), whose presence in standing ponds and puddles
+often imparts a greenish color to the water. Then in the salt water near
+the surface there are often myriads of minute _Noctiluca_ whose
+wonderfully phosphorescent little bodies glow like coals of fire when
+the water is disturbed at night. Although this class contains fewer
+forms than the preceding some of these have within recent years been
+found to be of great importance because they live as parasites on man
+and other animals. The trypanosome whose presence in the blood and
+tissues of the patient causes that dreadful disease which ends in
+sleeping sickness belongs here as well as do several other similar kinds
+that produce serious troubles for various mammals and birds. The
+Spirochaeta, about which there has been so much recent discussion, also
+belong here. These are simple spiral-like forms (Fig. 10), that are
+sometimes classed with the simple plants, bacteria, but Nuttall and
+others have shown very definitely that they should be classed with the
+simplest animals, the Protozoans. These are the cause of relapsing
+fevers in man and of several diseases of domestic animals. It is
+believed by certain eminent zooelogists that when the germ that causes
+yellow fever is discovered it will be found to belong to this group.
+
+The members of the class Infusoria, so called because they were early
+found to be abundant in various infusions, are characterized by numerous
+fine cilia or hair-like organs by means of which the organism moves
+about and procures its food. The well-known "slipper animalcule"
+(_Paramoecium_) (Fig. 11), and the "bell-animalcule" (_Vorticella_)
+(Fig. 12) are two common representatives. The _Paramoecia_ were the
+animals mostly used by Jennings in his wonderfully interesting
+experiments on the behavior of these lowly forms of life. He showed that
+they always reacted in a certain definite way in response to particular
+stimuli, and he was led to believe that he could see "what must be
+considered the beginnings of intelligence and of many other qualities
+found in the higher animals." A species of _Vorticella_ was probably the
+first Protozoan that was ever observed. An old Dutch microscopist, Anton
+von Leeuwenhoek, in 1675, while studying with lenses of his own
+manufacture, discovered and described forms which undoubtedly belong to
+this genus. Few if any of the Infusoria are pathogenic, although some
+are said to be associated with certain intestinal diseases both in man
+and the lower animals (Fig. 13).
+
+[Illustration: FIG. 11--_Paramoecium._ (From Kellogg's Elementary
+Zooel.)]
+
+[Illustration: FIG. 12--_Vorticella_, one individual with the stalk
+coiled, the other with the stalk extended. (From Kellogg's Elementary
+Zooel.)]
+
+[Illustration: FIG. 13--Pathogenic Protozoa; a group of intestinal
+parasites. _A_, _B_, _Megastoma entericum_, _C_, _Balantidum entozoon_.
+(After Calkins.)]
+
+The last class, the Sporozoa, or the spore-forming animals, while small
+in the number of known species, only about three hundred kinds being
+known, is extremely important. A number of diseases in man and other
+animals are due to the presence of these Sporozoans, for they are all
+parasitic. Few if any animals are exempt from their attacks. They even
+attack other minute Protozoa. One hundred and fifty-seven species have
+been recorded as attacking insects, one hundred species attack birds,
+fifty-two reptiles, eighty crustaceans, twenty-two fish, and so through
+the list. Ten have been recorded as attacking man. In some instances the
+parasite is always present in the host and some hosts may harbor several
+different species of Sporozoa.
+
+Very little work had been done on this group of parasites prior to 1900.
+Since that time most of the species that we now know have been
+discovered, and within the last few years the life-histories of many of
+these have been worked out quite completely. No other group of animals
+is being studied more to-day by both the physicians and biologists.
+
+The Sporozoa vary greatly in appearance, organization and life-history.
+They are so very plastic that they can adapt themselves readily to their
+various hosts, hence we have a great variety of forms. But they all
+agree in certain characters; all take their food and oxygen and carry on
+excretory processes by osmosis, _i.e._, through the body-wall; all are
+capable of some kind of locomotion, some have one or more flagella,
+others move by a pseudopod movement. Some are capable of moving from
+cell to cell in the body as do the white blood-corpuscles. They all
+agree in the production of spores--hence the name.
+
+At certain stages in their development the nucleus within the body of
+the organism divides again and again until there are a great many
+daughter nuclei, each accompanied by a small mass of protoplasm, often
+inclosed in a little sac or cyst of its own. This is the process of
+spore-formation and we see that from a single individual we may have by
+division, not two animals as in the amoeba, but a score or more of
+them. The little cysts or capsules that inclose them enable them to
+resist without injury many vicissitudes that would otherwise destroy
+them. They may dry up or freeze or lie for a long time in the ground or
+water until the time comes when they are introduced into another host.
+
+The class Sporozoa is divided into five small groups or orders. Nearly
+all of these contain forms that are of more or less importance, but the
+ones that live in the blood-cells (_Haemosporidiida_) are of the most
+interest to us because the parasites that cause the malarial fevers and
+various other diseases belong here. These are dependent on two hosts for
+their existence, the sexual generation usually occuring in an insect or
+other invertebrate and the asexual generation in some vertebrate.
+
+
+
+
+CHAPTER III
+
+TICKS AND MITES
+
+
+The other group or Phylum of animals with which we will be particularly
+concerned is known as the Arthropoda, which means "jointed-feet" and
+includes the crayfish, crabs, spiders, mites, ticks and insects. Of
+these only the last three are of interest to us now. It is customary to
+speak of spiders, mites and ticks as insects, but as they have four
+pairs of legs, instead of three pairs, in the adult stage, and as their
+bodies are not divided into three distinct regions as in the insects,
+they are placed in a different class.
+
+
+GENERAL CHARACTERS OF TICKS
+
+The ticks are all comparatively large, that is, they are all large
+enough to be seen with the unaided eye even in their younger stages and
+some grow to be half an inch long. When filled with blood the tough
+leathery skin becomes much distended often making the creature look more
+like a large seed than anything else (Fig. 14). This resemblance is
+responsible for some of the popular names, such as "castor-bean tick,"
+etc.
+
+The legs of most species are comparatively short, and the head is small
+so that they are often hardly noticeable when the body is distended. The
+sucking beak which is thrust into the host when the tick is feeding is
+furnished with many strong recurved teeth which hold on so firmly that
+when one attempts to pull the tick away the head is often torn from the
+body and left in the skin. Unless care is taken to remove this, serious
+sores often result.
+
+Ticks are wholly parasitic in their habits. Some of them live on their
+host practically all their lives, dropping to the ground to deposit
+their eggs when fully mature. Others leave their host twice to molt in
+or on the ground. The female lays her eggs, 1,000 to 10,000 of them, on
+the ground or just beneath the surface. The young "seed-ticks" that
+hatch from these in a few days soon crawl up on some near-by blade of
+grass or on a bush or shrub and wait quietly and patiently until some
+animal comes along. If the animal comes close enough they leave the
+grass or other support and cling to their new-found host and are soon
+taking their first meal. Of course thousands of them are disappointed
+and starve before their host appears, but as they are able to live for a
+remarkably long time without taking food their patience is often
+rewarded and the long fast ended.
+
+Those species which drop to the ground to molt must again climb to some
+favorable point and wait for another host on which they may feed for a
+while. Then they drop to the ground for a second molt and if they are
+successful in gaining a new host for the third time they feed and
+develop until fully mature and the female is ready to lay her eggs. The
+Texas fever tick, and some others, as we shall see, do not drop to the
+ground to molt but once having gained a host remain on it until ready to
+deposit their eggs.
+
+The young ticks have only six legs (Fig. 15) but after the first molt
+they all have eight.
+
+
+TICKS AND DISEASE
+
+_Texas Fever._ Ever since stockmen began driving southern cattle into
+states further north it has been noted that the roads over which they
+were driven became a source of great danger to northern cattle. Often
+80% to 90% of the native cattle died after a herd of southern cattle
+passed through their region and the losses became so great that both
+state and national laws were passed prohibiting the driving or shipping
+of southern cattle into northern states.
+
+[Illustration: FIG. 14--Castor Bean Tick (_Ixodes ricinus_) not fully
+gorged.]
+
+[Illustration: FIG. 15--Texas fever tick, just hatched; has only six
+legs.]
+
+[Illustration: FIG. 16--Texas fever tick (_Margaropus annulatus_) young
+adult not fully gorged.]
+
+[Illustration: FIG. 17--_Amblyomma variegatum_ several ticks belonging
+to this genus transmit _Piroplasma_ which cause various diseases of
+domestic animals.]
+
+But for years the cause of this fever, which came to be known as the
+Texas fever, was not known. The southern cattle themselves seemed
+healthy enough and it was difficult to understand how they could give
+the disease to the others. It was early noticed, too, that it was not
+necessary for the northern cattle to come in direct contact with the
+others in order to contract the disease. Indeed the disease was not
+contracted in this way at all. All that was necessary for them was to
+pass along the same roads or feed in the same pastures or ranges. Still
+more puzzling was the fact that these places did not seem to become a
+source of danger until some weeks after the southern cattle had passed
+over them and then they might remain dangerous for months.
+
+In 1886 Dr. Theobald Smith of the Bureau of Animal Industry, United
+States Department of Agriculture, found that the fever was caused by the
+presence in the infected cattle of a minute Sporozoan parasite
+(_Piroplasma bigeminum_). Further investigations and experiments proved
+conclusively that this parasite was transmitted from the infected to the
+well animal only by the common cattle tick now known as the Texas fever
+tick (Fig. 16).
+
+The infection is not direct, that is, the tick does not feed on one
+host then pass to another carrying the disease germs with it. Unlike
+many other ticks the Texas fever tick does not leave its host until it
+is fully developed. When the female is full grown and gorged she drops
+to the ground and lays from 2,000 to 4,000 eggs which soon hatch into
+the minute "seed-ticks" which make their way to the nearest blade of
+grass or weed or shrub and patiently wait for the cattle to come along.
+
+If the mother tick had been feeding on an animal that was infected with
+the Texas fever parasite, her body was filled with the minute organisms
+of which some found their way into the eggs so that the young ticks
+hatching from them were already infected and ready to carry the
+infection to the first animal they fed upon.
+
+It took many years of hard patient work to learn all this, but the
+knowledge thus obtained cleared up much of the mystery in connection
+with the occurrence of the fever in the north and, as we shall see,
+suggested the possibility of other diseases being communicated in the
+same way.
+
+It was found that the southern cattle in the region where the ticks
+occur normally, usually have a mild attack of the disease when they are
+young and although they may be infected with the parasite all the rest
+of their lives it does not affect them seriously. These cattle are
+almost always infected with ticks, and when taken north where the ticks
+do not occur naturally and where the cattle are therefore non-immune,
+some of the mature ticks drop to the ground and lay their eggs which in
+a few weeks hatch out and are ready to infect any animal that passes by.
+The northern cattle not being used to the disease soon sicken and die.
+
+It is estimated that the annual loss due to this disease and the ravages
+of the tick in the United States is over $100,000,000, so of course most
+determined efforts are being made to stamp it out. Formerly various
+devices for dipping the tick-infested cattle into some solution that
+would kill the ticks were resorted to, but it was always expensive and
+never very satisfactory. The immunizing of the cattle by inoculating
+them when they were young with infected blood has been practised. Very
+recent investigations have shown that it is possible and practicable to
+rid pastures of ticks by a system of feed-lots and pasture rotation. The
+aim is to have as many of the ticks as possible drop to the ground on
+land where they may be destroyed and to so regulate the use of the
+pasture that the ticks in all of them may eventually be left to starve.
+
+Several similar diseases of cattle, many of them probably identical
+with Texas fever, occur in other parts of the world where the losses are
+sometimes appalling. Horses, sheep, dogs, and other animals are also
+affected with diseases caused by the same group of Protozoan parasites.
+Most of them have been shown to be transmitted by various species of
+ticks (Fig. 17) so that from an economical standpoint these little pests
+are becoming of prime importance. Not only do they transmit the disease
+germs that infect domestic animals but they are known to be responsible
+for at least two diseases of men, Rocky Mountain spotted fever and the
+relapsing fevers.
+
+_Spotted Fever._ The first of these is a disease that for some years has
+been puzzling the physicians in Idaho and Montana and other mountainous
+states. A few years ago certain observers recorded finding Protozoan
+parasites in the blood of those suffering from the disease, and although
+more recent investigations have failed to confirm these particular
+observations it is now quite generally believed that the disease is
+caused by some such parasite and that the organism is transferred from
+one host to another by certain species of ticks that live on wild
+mammals of the region where the disease exists. Dr. H.T. Ricketts, who
+has made a special study of the disease, has shown:
+
+     "1. That the period of activity of the disease is limited to the
+     season during which the adult female and male ticks attack man.
+
+     "2. That in practically all cases of this disease it can be shown
+     that the patient has been bitten by a tick.
+
+     "3. That the period between the tick bite and the onset of the
+     disease in the many animals he has experimented with corresponds
+     very closely to this period as observed in man.
+
+     "4. That infected ticks are to be found in the locality where the
+     disease occurs.
+
+     "5. That the virus of spotted fever is very intimately associated
+     with the tissues of the tick's body as is shown by the fact that
+     the female passes the infection on to her young through her eggs,
+     and further, by the observation that in either of the two earlier
+     stages of the life cycle the disease may be contracted by biting a
+     sick animal and communicated to other animals after molting or even
+     after passing through an intermediate stage."
+
+Professor R.A. Cooley of Montana, from whose report the above quotation
+is taken, has also made studies of the habits of the tick and believes
+there can be no doubt that it is the disseminator of the disease.
+
+_Relapsing Fever._ The relapsing fever is an infectious disease or
+possibly a group of closely related infectious diseases occurring in
+various parts of the world. Occasionally it is introduced into America,
+but it does not seem to spread here. It has been shown that the disease
+is communicated from one person to another by means of blood-sucking
+insects. In Central Africa where the disease is very prevalent a certain
+common tick (_Ornithodoros moubata_) (Fig. 18) is known to transmit the
+disease. This tick lives in the resting places and around the huts of
+the natives and has habits very similar to the bedbug of other climes,
+feeding at night and hiding during the day. It attacks both man and
+beast and is one of the most dreaded of all the African pests.
+
+Nathan Bank, our foremost authority on ticks, in summing up the evidence
+against them says:
+
+     "It is therefore evident that all ticks are potentially dangerous.
+     Any tick now commonly infesting some wild animal, may, as its
+     natural host becomes more uncommon, attach itself to some domestic
+     animal. Since most of the hosts of ticks have some blood-parasites,
+     the ticks by changing the host may transplant the blood-parasites
+     into the new host producing, under suitable conditions, some
+     disease. Numerous investigators throughout the world are studying
+     this phase of tick-life, and many discoveries will doubtless
+     signalize the coming years."
+
+
+MITES
+
+The mites are closely related to the ticks, and although none of them
+has yet been shown to be responsible for the spread of any disease their
+habits are such that it would be entirely possible for some to transmit
+certain diseases from one host to another, from animal to animal, from
+animal to man, or from man to man. A number of these mites produce
+certain serious diseases among various domestic animals and a few are
+responsible for certain diseases of men.
+
+_Face-mites._ Living in the sweat-glands at the roots of hairs and in
+diseased follicles in the skin of man and some domestic animals are
+curious little parasites that look as much like worms as mites (Fig.
+19). Such diseased follicles become filled with fatty matter, the upper
+end becomes hard and black and in man are known as blackheads. If one of
+these blackheads is forced out and the fatty substance dissolved with
+ether the mites may be found in all stages of development. The young
+have six legs, the adult eight. The body is elongated and transversely
+wrinkled. In man they are usually found about the nose and chin and neck
+where they do no particular harm except to mar the appearance of the
+host and to indicate that his skin has not had the care it should have.
+Very recently certain investigators have found that the leprae bacilli
+are often closely associated with these face mites and believe that they
+may possibly aid in the dissemination of leprosy. It is also thought
+that they may sometimes be the cause of cancer, but as yet these
+theories have not been proven by any conclusive experiment.
+
+In dogs and cats these same or very similar parasites cause great
+suffering. In bad cases the hair falls out and the skin becomes scabby.
+Horses, cattle and sheep are also attacked. The disease caused by these
+mites on domestic animals is not usually considered curable except in
+its very early stages when salves or ointments may help some.
+
+_Itch-mites._ "As slow as the seven-years' itch" is an expression, the
+meaning of which many could appreciate from personal experience, for it
+certainly seemed to take no end of time to get rid of the itch once it
+was contracted. Just why seven years should have been set for the limit
+of the disease is not clear, for if the little roundish mites that cause
+the disease live for seven years on a host they are not going to move
+out voluntarily even if their seven-year lease has expired.
+
+[Illustration: FIG. 18--_Ornithodorus moubata_, the Tick that Transmits
+Relapsing Fever. From Boyce's "Mosquito or Man."]
+
+[Illustration: FIG. 19--The follicle mite (_Demodex folliculorum_).
+(After Murray.)]
+
+[Illustration: FIG. 20--Itch-mite (_Sarcoptes scabiei_). (After
+Murray.)]
+
+[Illustration: FIG. 21--Harvest-mites or "jiggers." (_Leptus irritaus_
+and _L. americanus_.) (After Riley.)]
+
+The minute whitish mites (Fig. 20) that cause this disgusting disease
+are barely visible to the naked eye. They are usually very sluggish but
+become more active when warmed. They live in burrows just beneath the
+outer layer of skin, sometimes extending deeper and causing most intense
+itching. As the female burrows, she lays her eggs from which come the
+young mites that are to spread the infection. Various sulphur ointments
+and washes are used as remedies. Cleanliness will prevent infection.
+
+Closely related to the itch-mite of man (_Sarcoptes scabiei_) are
+several kinds attacking domestic animals, causing mange, scab, etc. The
+variety infesting horses burrows in the skin and produces sores and
+scabs, and is a source of very great annoyance. These mites may also
+migrate to man. Tobacco water and sulphur ointments are used as
+remedies.
+
+Horses and cattle are also infested by other mites (_Psoroptes
+communis_) which cause the common mange. These do not burrow into the
+skin but live outside in colonies, feeding on the skin and causing
+crusts or scabs. The inflammation causes the animal to scratch and rub
+constantly and often causes the loss of much of the hair.
+
+_Harvest-mites._ A score or more of different varieties of mites cause
+many other diseases of domestic animals, such as the scab of sheep and
+hogs and chickens, various other manges of the horses and cattle and
+dogs, etc. But we need to call attention to just one more example, that
+of the harvest-mites or jiggers (Fig. 21). Professor Otto Lugger, from
+whose report on the _Parasites of Man and Domestic Animals_ most of
+these notes in regard to the mites are taken, thus feelingly refers to
+this pest.
+
+     "About the very worst pests of man and domesticated animals are the
+     Harvest-bugs, Red-bugs or Jiggers.... Men and animals passing
+     through low herbage that harbors them are attacked by these pests,
+     which, whenever they succeed in finding a host, burrow in and under
+     the skin, causing intolerable itching and sores, the latter caused
+     by the feverish activity of the finger-nails of the host, if that
+     should be a man, whose energy in scratching, apparently, cannot be
+     controlled and who is bound forcibly to remove the intruders. The
+     writer has been there! Those who have ever passed through meadows
+     infested with red-bugs will remember the occasion."
+
+Horses, cattle, dogs and cats and other animals suffer also. Again
+sulphur ointments are the best remedies.
+
+     "The normal food of these mites must, apparently, consist of the
+     juices of plants, and the love of blood proves ruinous to those
+     individuals which get a chance to indulge it. For, unlike the true
+     chigoe, the female of which deposits eggs in the wound she makes,
+     these harvest-mites have no object of the kind, and when not killed
+     at the hands of those they torment they soon die victims to their
+     sanguinary appetite."
+
+
+
+
+CHAPTER IV
+
+HOW INSECTS CAUSE OR CARRY DISEASE
+
+
+It has been estimated that there are about four thousand species or
+kinds of Protozoans, about twenty-five thousand species of Mollusks,
+about ten thousand species of birds, about three thousand five hundred
+species of mammals, and from two hundred thousand to one million species
+of insects, or from two to five times as many kinds of insects as all
+other animals combined.
+
+Not only do the insects preponderate in number of species, but the
+number of individuals belonging to many of the species is absolutely
+beyond our comprehension. Try to count the number of little green aphis
+on a single infested rose-bush, or on a cabbage plant; guess at the
+number of mosquitoes issuing each day from a good breeding-pond;
+estimate the number of scale insects on a single square inch of a tree
+badly infested with San Jose scale; then try to think how many more
+bushes or trees or ponds may be breeding their millions just as these
+and you will only begin to comprehend the meaning of this statement.
+
+As long as these myriads of insects keep in what we are pleased to call
+their proper place we care not for their numbers and think little of
+them except as some student points out some wonderful thing about their
+structure, life-history or adaptations. But since the dawn of history we
+find accounts to show that insects have not always kept to their proper
+sphere but have insisted at various times and in various ways in
+interfering with man's plans and wishes, and on account of their
+excessive numbers the results have often been most disastrous.
+
+Insects cause an annual loss to the people of the United States of over
+$1,000,000,000. Grain fields are devastated; orchards and gardens are
+destroyed or seriously affected; forests are made waste places and in
+scores of other ways these little pests which do not keep in their
+proper places are exacting this tremendous tax from our people.
+
+These things have been known and recognized for centuries, and scores of
+volumes have been written about the insects and their ways and of
+methods of combating them.
+
+But it is only in recent years that we have begun to realize the really
+important part that insects play in relation to the health of the people
+with whom they are associated. Dr. Howard estimates that the annual
+death rate in the United States from malaria is about twelve thousand,
+entailing an annual monetary loss of about $100,000,000, to say nothing
+of the suffering and misery endured by the afflicted. All this on
+account of two or three species of insects belonging to the mosquito
+genus _Anopheles_.
+
+Yellow fever, while not so widespread, is more fatal and therefore more
+terrorizing. Its presence and spread are due entirely to a single
+species of mosquito. Flies, fleas, bedbugs, and many other insects have
+been shown to be intimately connected with the spread of several other
+most dreaded diseases, so it is no wonder that physicians, entomologists
+and biologists are studying with utmost zeal many of these forms that
+bear such a close relation not only to our welfare and comfort but to
+our lives as well.
+
+It would be out of place to try to give here even a brief outline of the
+classification of insects, such as may be found in almost any of the
+many books devoted to their study.
+
+The most generally accepted classification divides the insects into
+nineteen orders; as the Coleoptera, containing the beetles; the
+Lepidoptera, containing the butterflies and moths; the Hymenoptera
+containing the bees, ants and wasps, etc. Four or five of these orders
+will be of more or less interest to us.
+
+The order Diptera, or two-winged flies, is the most important because to
+this belong the mosquitoes which transmit malaria and yellow fever, and
+the house-fly that has come into prominence since it has been found to
+be such an important factor in the distribution of typhoid and other
+diseases.
+
+
+FLIES
+
+The order Diptera is divided into sixty or more families, many of which
+contain species of considerable economic importance. For our present
+consideration the flies may be divided into two groups or sections:
+those with their mouth-parts fitted for piercing such as the mosquito
+and horse-fly, and those with sucking mouth-parts such as the house-fly,
+blow-fly and others.
+
+Some of the species belonging to the first group are among the most
+troublesome pests not only of man but of our domestic animals as well.
+Next to the mosquitoes the horse-flies (Fig. 22) are perhaps the best
+known of these. There are several species known under various names,
+such as gad-fly, breeze-fly, etc. They are very serious pests of horses
+and cattle, sometimes also attacking man. Their strong, sharp, piercing
+stylets enable them to pierce through the toughest skin of animals and
+through the thin clothing of man. The bite is very severe and
+irritating, and as the flies sometimes occur in great numbers the
+annoyance that they cause is often very great indeed. It has often been
+claimed that these flies as well as the stable-fly and others carry the
+anthrax bacillus on their proboscis from one animal to another, and
+although this may not have been definitely proven the evidence is strong
+enough to make a very good case against the accused. It is interesting
+to note in this connection that anthrax, a very common disease among the
+domestic animals and one which may attack man also, was the first
+disease to be shown to be of bacterial origin. It was only about
+thirty-five years ago that the investigations of Koch and Pasteur
+demonstrated that the presence of this particular germ (_Bacillus
+anthracis_) was the cause of the disease, and it was early recognized
+that such biting flies may be important factors in the spread of the
+disease.
+
+[Illustration: FIG. 22--Horse-fly (_Tabanus punctifer_).]
+
+[Illustration: FIG. 23--Stable-fly (_Stomoxys calcitrans_).]
+
+[Illustration: FIG. 24--A Black-fly (_Simulium sp._). (From Kellogg's
+Amer. Insects.)]
+
+[Illustration: FIG. 25--Screw-worm fly (_Chrysomyia macellaria_).]
+
+[Illustration: FIG. 26--Blow-fly (_Calliphora vomitoria_).]
+
+The stable-fly (Fig. 23) (_Stomoxys calcitrans_) which looks very much
+like the house-fly and, as will be noted later, frequently enters
+houses, is often an important pest of horses and cattle. Its
+blood-sucking habit makes it quite possible that it too may be concerned
+in carrying anthrax and other diseases.
+
+In a later chapter it will be shown how the tsetse-fly, which is
+somewhat like the stable-fly, is responsible for the spread of the
+disease known as the sleeping sickness. This disease is caused by a
+Protozoan parasite, a trypanosome, which is transmitted from one host to
+another by the tsetse-fly.
+
+In Southern Asia and in parts of Africa there is a very serious disease
+of horses known as surra which is caused by a similar parasite
+(_Trypanosoma evansi_). This parasite attacks horses, mules, camels,
+elephants, buffaloes and dogs, and has been recently imported into the
+Philippines. It is supposed that flies belonging to the same genus as
+the horse-fly (_Tabanus_ and others), and the stable-fly (_Stomoxys_)
+and the horn-fly (_Haematobia_) are responsible for the spread of the
+disease.
+
+Nagana is one of the most serious diseases of domestic animals in
+Central and Southern Africa. In some sections it is almost impossible to
+keep any kind of imported animals on account of this disease which is
+caused by a parasite (_Trypanosoma brucei_) similar to the one causing
+surra. This parasite is to be found in several different kinds of
+native animals which seem to be practically immune but are always a
+source of danger when other animals are introduced. Two or three species
+of tsetse-flies are responsible for the transmission of this disease.
+
+Another group of flies much smaller but more numerous and much more
+insistent are the black-flies or buffalo-gnats (Fig. 24). For more than
+a century these little flies have been recognized as among the most
+serious pests of stock, particularly in the south where, besides the
+actual loss by death of many animals yearly, the annoyance is so great
+as to sometimes make it impossible to work in the field. Human beings
+are often attacked, and as the bite is poisonous and very painful great
+suffering may result and cases of deaths from such bites have been
+reported.
+
+Belonging to another family, and smaller, but much like the buffalo-gnat
+in habits, are the minute little "punkies" or "no-see-ums" which
+sometimes occur in great swarms in certain regions where they make life
+a burden to man and beast. While it has not been shown that either the
+buffalo-gnats or the punkies are responsible for the transmission of any
+disease, their habits of feeding on so many different kinds of wild and
+domestic animals as well as on man makes it possible for them to act as
+carriers of parasites that might under proper conditions become of
+serious importance. Then, too, the irritation caused by the bites of
+these insects usually causes scratching which may result in abrasions of
+the skin that open the way for various harmful germs, particularly those
+causing skin diseases.
+
+Coming now to the group containing the house-flies and related forms we
+find a number that are of interest on account of the suffering that they
+may cause, particularly in their larval stages.
+
+The screw-worm flies (_Chrysomyia macellaria_) are among the most common
+and important of these (Fig. 25). These "gray flies," as they are
+sometimes called, lay a mass of three or four hundred eggs on the
+surface of wounds. The larvae which in a few hours hatch from these make
+their way directly into the wound where they feed on the surrounding
+tissue until full grown when they wriggle out and drop to the ground
+where they transform to the pupa and later to the adult fly. Of course
+their presence in the wounds is very distressing to the infected animal,
+and great suffering results. Slight scratches that might otherwise
+quickly heal often become serious sores because of the presence of these
+larvae.
+
+Many cases are recorded of these flies laying their eggs in the ears or
+nose of children or of persons sleeping out of doors during the day.
+Especially is this apt to occur if there are offensive discharges which
+attract the fly. In such cases the larvae burrow into the surrounding
+tissues, devouring the mucous membranes, the muscles and even the bones,
+causing terrible suffering and usually, death. The larvae in such
+situations may be killed with chloroform and, if the case is attended to
+before they have destroyed too much of the tissues, recovery usually
+occurs.
+
+The blow-flies (Fig. 26) (_Calliphora vomitoria_) and the blue-bottle
+flies (Fig. 27), (_Lucilia spp._) and the flesh-flies (Fig. 28)
+(_Sarcophaga spp._) all have habits somewhat like the screw-worm fly.
+Any of them may lay their eggs in wounds on man or animals with the same
+serious results.
+
+The flesh-fly instead of laying eggs deposits the living larvae upon meat
+wherever it is accessible, and as these develop with astonishing
+rapidity they are able to consume large quantities of flesh in a
+remarkably short time. In this way they may be of some importance as
+scavengers, but it is better to get rid of the waste in other ways than
+to leave it for a breeding-place for flies that are capable of causing
+so much damage and suffering.
+
+Not infrequently the larvae of certain flies are to be found in the
+alimentary canal where as a rule they do no particular damage.
+Altogether the larvae of over twenty different species of flies have been
+found in or expelled from the human intestinal canal. In Europe, the
+majority of these larvae belong to a fly which looks very much like the
+house-fly except that it is somewhat smaller and so is often known as
+"the little house-fly" (Fig. 29) (_Homalomyia canicularis_). The same
+species is very common in the United States, frequently occurring in
+houses. Under certain conditions it may even be more abundant than the
+house-fly. It is believed that the larvae in the intestinal canal come
+from eggs that have been deposited on the victim while using an outdoor
+privy where the flies are often very abundant. Instances are also on
+record where these larvae have been discharged from the urethra.
+
+Another fly (_Ochromyia anthropophaga_) occurring in the Congo region
+has a blood-sucking larvae which is known as the Congo floor-maggot. The
+fly which is itself not troublesome deposits its eggs in the cracks and
+crevices of the mud floors of the huts. The larvae which hatch from these
+crawl out at night and suck the blood of the victim that may be sleeping
+on the floor or on a low bed.
+
+
+BOT-FLIES
+
+Another group of flies known as the bot-flies (Fig. 30) have their
+mouth-parts rudimentary or entirely wanting so of course they themselves
+cannot bite or pierce an animal. Nevertheless they are the source of an
+endless amount of trouble to stockmen and sometimes even attack man.
+Although these flies cannot bite, the presence of even a single
+individual may be enough to annoy a horse almost to the end of
+endurance. Horses seem to have an instinctive fear of them and will do
+all in their power to get rid of the annoying pests.
+
+The eggs of the house bot-fly are laid on the hair of the legs or some
+other part of the body. The horse licks them off and they hatch and
+develop in the alimentary canal of their host. Sometimes the walls of
+the stomach may be almost covered with them thus of course seriously
+interfering with the functions of this organ. When full grown the larvae
+pass from the host and complete their transformation in the ground.
+
+[Illustration: FIG. 27--Blue-bottle fly (_Lucilia sericata_).]
+
+[Illustration: FIG. 28--Flesh-fly (_Sarcophaga sp_).]
+
+[Illustration: FIG. 29--"The little house-fly" (_Homalomyia
+canicularis_).]
+
+[Illustration: FIG. 30--Horse bot-fly (_Gastrophilus equi_).]
+
+[Illustration: FIG. 31--Ox warble-fly (_Hypoderma lineata_).]
+
+[Illustration: FIG. 32--Sheep bot-fly (_Gastrophilus nasalis_).]
+
+The bot-flies of cattle or the oxwarbles (Fig. 31) gain an entrance
+into the alimentary canal in the same way, that is, by the eggs being
+licked from the hairs on the body where they have been laid by the adult
+fly. But instead of passing on into the stomach they collect in the
+esophagus and later make their way through the walls of this organ and
+through the tissues of the body until they at last reach a place along
+the back just under the skin. Here as they are completing their
+development they make more or less serious sores on the backs of the
+infested animals. The hides on such animals are rendered nearly
+valueless by the holes made by the larvae. When fully mature they drop to
+the ground and complete their transformations.
+
+The sheep bot-flies (Fig. 32) lay their eggs in the nostrils of sheep.
+The larvae pass up into the frontal sinuses where they feed on the mucus,
+causing great suffering and loss. Many other species of animals are
+infested with their own particular species of bots. Several instances
+are recorded where the oxwarble has occurred in man, always causing much
+suffering and sometimes death.
+
+One or more species of bot-flies occurring in the tropical parts of
+America frequently attack man. The early larval stage soon after it has
+entered the skin is known as the _Ver macaque_. Later stages as _torcel_
+or _Berne_. The presence of the larvae produces very painful and
+troublesome sores. It is supposed that the adult flies (one species of
+which is _Dermatobia cyaniventris_) lay their eggs on the skin which
+the larvae penetrate as soon as they hatch. It has also been suggested
+that they might reach the subcutaneous tissue by migrating from the
+alimentary canal as do some of the other bot-flies. A very serious eye
+disease, _Egyptian opthalmia_, is known to be spread by the house-flies
+and others. These flies are often abundant about the eyes, especially of
+children suffering from this disease. It is suspected that certain small
+flies (Oscinidae) in the southern part of the United States are
+responsible for the spread of disease known as "sore eye."
+
+
+FLEAS
+
+The fleas used to be considered as degenerate Diptera and were placed
+with that group but they are now classed as a separate order
+(Siphonaptera). Within recent years these little pests have come into
+special prominence on account of their importance in connection with the
+spread of the plague. The fact that they are so abundant everywhere and
+that they will so readily pass from one host to another makes the
+possibility of their spreading infectious diseases very great. Besides
+the kinds that are concerned in the transmission of plague, which are
+discussed in another chapter, there are many other kinds infesting
+various wild and domesticated animals and a few attacking birds.
+
+One of the most important of these is the jigger-flea or chigoe
+(_Dermatophilus penetrans_, Fig. 33). Various other names such as
+chigger-flea, sand-flea, jigger, chigger are also applied to this insect
+as well as to a minute red mite that burrows into the skin in much the
+same way as the female of the flea. So although they are entirely
+different creatures you can never tell from the common name, whether it
+is the flea or the mite that is being referred to. Both the male and
+female jigger-fleas feed on the host and hop on or off as do other
+fleas, but when the female is ready to lay eggs (Fig. 34), she burrows
+into the skin. Her presence there causes a swelling and usually an ulcer
+which often becomes very serious, especially if the insect should be
+crushed and the contents of the body escape into the surrounding tissue.
+
+These little pests are found throughout tropical and subtropical America
+and have been introduced into Africa and from there have spread to India
+and elsewhere. They attack almost all kinds of animals as well as many
+birds, being of course a source of great annoyance and no inconsiderable
+loss. They are more apt to attack the feet of men, especially those who
+go barefooted. Sometimes they occur in such numbers as to make great
+masses of sores.
+
+On account of being such general feeders they are difficult to control,
+but some relief may be obtained by keeping the houses and barns as free
+as possible from dirt and rubbish and by sprinkling the breeding-places
+of the pest with pyrethrum powder or carbolic water. Those that gain an
+entrance into the skin should be cut out, care being taken to remove the
+insect entire.
+
+
+BEDBUGS
+
+In the order Hemiptera, or the true "bugs" in an entomological sense, we
+find a few forms that may carry disease. The bedbug (Fig. 35) (_Cimex
+lectularis_) has been accused of transmitting plague, relapsing fever
+and other diseases. Very recent investigations show that the common
+bedbug of India (_Cimex rotundatus_) harbors the parasite that causes
+the disease known as _kala azar_, and there is no doubt that it
+transmits the disease.
+
+
+LICE
+
+The sucking lice (Fig. 36) which also belong to this order are suspected
+of carrying some of these same diseases. It is thought that the common
+louse on rats (_Haematopinus spinulosus_) is responsible for the spread
+from rat to rat of a certain parasite. (_Trypanosoma lewisi_), which,
+however, does not produce any disease in the rats, but if they are
+capable of acting as alternative hosts for such parasites, it is quite
+possible that they may also carry disease-producing forms.
+
+[Illustration: FIG. 33--Chigo or jigger-flea, male (_Dermatophilus
+penetrans_). (After Karsten.)]
+
+[Illustration: FIG. 34--Chigo, female distended with eggs. (After
+Karsten.)]
+
+[Illustration: FIG. 35--Bedbug (_Cimex lectularis_).]
+
+[Illustration: FIG. 36--Body-louse (_Pediculus vestimenti_). (From
+drawing by J.H. Paine.)]
+
+
+HOW INSECTS MAY CARRY DISEASE GERMS
+
+Insects may carry the germs or parasites which cause disease in a purely
+mechanical or accidental way, that is, the insect may in the course of
+its wanderings or its feeding get some of the germs on or in its body
+and may by chance carry these to the food, or water, or directly to some
+person who may become infected. Thus the house-fly may carry the typhoid
+germs on its feet or in its body and distribute them in places where
+they may enter the human body.
+
+Several other flies as well as fleas, bedbugs, ticks, etc., may also
+carry disease germs in this mechanical way. While this method of
+transmission is just as dangerous as any other, and possibly more
+dangerous because more common, another method in which the insect is
+much more intimately concerned is more interesting from a biological
+standpoint at least and will be discussed more fully in the chapters on
+malaria, yellow fever and elephantiasis.
+
+In these cases the insect is one of the necessary hosts of the parasite,
+which cannot go on with its development or pass from one patient to
+another unless it first enters the insect at a certain stage of its
+life-history.
+
+[Illustration: FIG. 37--One use for the house-fly.]
+
+BABY-BYE.
+
+  1. Baby-Bye,
+  Here's a fly;
+  We will watch him, you and I.
+    How he crawls
+    Up the walls,
+    Yet he never falls!
+  I believe with six such legs
+  You and I could walk on eggs.
+    There he goes
+    On his toes,
+    Tickling Baby's nose.
+
+
+
+
+CHAPTER V
+
+HOUSE-FLIES OR TYPHOID-FLIES
+
+
+The page shown in Fig. 37 was copied from one of our old second readers
+and shows something of the spirit in which we used to regard the
+house-fly. A few of them were nice things to have around to make things
+seem "homelike." Of course they sometimes became too friendly during the
+early morning hours when we were trying to take just one more little nap
+or they were sometimes too insistent for their portion of the dinner
+after it had been placed on the table, but a screen over the bed would
+help us out a little in the morning and a long fly-brush cut from a tree
+in the yard or made of strips of paper tacked to a stick or, still more
+fancy, made of long peacock plumes, would help to drive them from the
+table. Those that were knocked into the coffee or the cream could be
+fished out; those that went into the soup or the hash were never missed!
+
+Not only were the flies regarded as splendid things with which to amuse
+the baby, but they were thought to be very useful as scavengers as they
+were often seen feeding on all kinds of refuse in the yard. Then, too,
+they seemed to be cleanly little things, for almost any time some of
+them could be seen brushing their heads and bodies with their legs and
+evidently having a good clean-up. More than that it never occurred to us
+that it would be possible to get rid of them even should it be thought
+advisable, for they came from "out doors," and who could kill all the
+flies "out doors"?
+
+Fortunately, or otherwise, these halcyon days have gone by and the
+common, innocent, friendly little house-fly is now an outcast convicted
+of many crimes and accused of a long list of others (Fig. 38).
+
+Its former friends have become its sworn enemies. The foremost
+entomologist of the land has suggested that we even change its name and
+give it one that would be more suggestive of the abhorence with which we
+now look upon it.
+
+[Illustration: FIG. 38--The house-fly (_Musca domestica_).]
+
+And all these changes have come about because science has turned the
+microscope on the house-fly and men have studied its habits. We know now
+that as the fly is "tickling baby's nose" it may be spreading there
+where they may be inhaled or where they may be taken into the baby's
+mouth thousands of germs some of which may cause some serious disease.
+We know that as they are buzzing about our faces while we are trying to
+sleep they may, unwittingly, be in the same nefarious business, and we
+know that as they sip from our cups with us or bathe in our coffee or
+our soup or walk daintily over our beefsteak or frosted cake they are
+leaving behind a trail of filth and bacteria, and we know that some of
+these germs may be and often are the cause of some of our common
+diseases. As the typhoid germs are very often distributed in this way,
+Dr. Howard has suggested that the house-fly shall be known in the future
+as the typhoid-fly, not because it is solely responsible for the spread
+of typhoid, but because it is such an important factor in it and is so
+dangerous from every point of view. The names "manure fly" and "privy
+fly" have also been suggested and would perhaps serve just as well, as
+the only object in giving it another name would be to find a more
+repulsive one to remind us constantly of the filthy and dangerous habits
+of the fly.
+
+
+STRUCTURE
+
+In order that we may better understand why it is that the house-fly is
+capable of so much mischief, let us consider briefly a few points in
+regard to its structure, its methods of feeding and its life-history.
+
+The large compound eyes are the most conspicuous part of the head (Fig.
+39). In front, between the eyes, are the three-jointed antennae, the last
+joint bearing a short, feathery bristle. From the under side of the head
+arises the long, fleshy proboscis (Fig. 40). When this is fully extended
+it is somewhat longer than the head; when not distended and in use it is
+doubled back in the cavity on the under side of the head. About half-way
+between the base and the middle is a pair of unjointed mouth-feelers
+(maxillary palpi). At the tip are two membranous lobes (Fig. 41) closely
+united along their middle line. These are covered with many fine
+corrugated ridges, which under the microscope look like fine spirals and
+are known as pseudotracheae. Thus it will be seen that the house-fly's
+mouth-parts are fitted for sucking and not for biting. Its food must be
+in a liquid or semi-liquid state before it can be sucked through the
+tube leading from the lobes at the tip up through the proboscis and on
+into the stomach. If the fly wishes to feed on any substance such as
+sugar, that is not liquid, it first pours out some saliva on it and then
+begins to rasp it with the rough terminal lobes of the proboscis, thus
+reducing the food to a consistency that will enable the fly to suck it
+up. Many people think that house-flies can bite and will tell you that
+they have been bitten by them. But a careful examination of the
+offender, in such instances, will show that it was not a house-fly but
+probably a stable-fly, which does have mouth-parts fitted for piercing.
+
+[Illustration: FIG. 39--Head of house-fly showing eyes, antennae and
+mouth-parts.]
+
+[Illustration: FIG. 40--Proboscis of house-fly, side view.]
+
+[Illustration: FIG. 41--Lobes at end of proboscis of house-fly showing
+corrugated ridges.]
+
+[Illustration: FIG. 42--Wing of house-fly.]
+
+The thorax bears the two rather broad, membranous wings (Fig. 42) which
+have characteristic venation. Three of these veins end rather close
+together just before the tip of the wing, the posterior one of the group
+being bent forward rather sharply a short distance from the tip. The
+stable-fly has this vein slightly curved forward but not nearly so
+conspicuously (Fig. 43).
+
+Nearly all the other flies that are apt to be mistaken for the house-fly
+do not have this vein curved forward. The wings, although apparently
+bare, are covered with a fine microscopic pubescence. Among these fine
+hairs on the wing as well as among similar fine ones and coarser ones
+all over the body, particles of dust and dirt or filth (Fig. 44) or,
+what interests us more just now, thousands of germs may find a temporary
+lodgment and later be scattered through the air as the insect flies. Or
+they may get on our food as the fly feeds or while it rests and combs
+its body with the rows of coarse hairs on its legs.
+
+The legs are rather thickly covered with coarse hairs or bristles and
+with a mat of fine, short hairs. On some of the segments the larger
+hairs are arranged in rows and are used as a sort of comb with which the
+fly combs the dirt from the rest of its body. The last segment (Fig. 45)
+of the leg bears at its tip a pair of large curved claws and a pair of
+membranous pads known as the pulvillae. On the under side of the pulvillae
+are innumerable minute secreting hairs (Fig. 46) by means of which the
+fly is able to walk on the wall or ceiling or in any position on
+highly-polished surfaces.
+
+
+HOW THEY CARRY BACTERIA
+
+These same little pads, with their covering of secreting hairs, are
+perhaps the most dangerous part of the insect for they cannot help but
+carry much of the filth over or through which the fly walks, and as this
+may be well stocked with germs the danger is at once apparent.
+
+As the result of a series of carefully planned experiments it has been
+demonstrated that the number of bacteria on a single fly may range all
+the way from 550 to 6,600,000 with an average for the lot experimented
+with of about one and one-fourth million bacteria to each fly. Now where
+do all these bacteria come from? Necessarily from the place where the
+fly breeds or where it feeds.
+
+[Illustration: FIG. 43--Wing of Stable-fly (_Stomoxys calcitrans_).]
+
+[Illustration: FIG. 44--Wing of house-fly showing particles of dirt
+adhering to it.]
+
+[Illustration: FIG. 45--Last three segments of leg of house-fly showing
+the claws, the pulvillae and the hairs on the legs.]
+
+[Illustration: FIG. 46--Foot of house-fly showing claws, hairs,
+pulvillae and the minute clinging hairs on the pulvillae.]
+
+[Illustration: FIG. 47--Larva of house-fly.]
+
+
+LIFE-HISTORY AND HABITS
+
+The eggs of the house-fly may be laid on almost any kind of decaying or
+fermenting material. If this is kept moist and a proper temperature
+maintained the larvae or maggots (Fig. 47) that hatch from the eggs may
+develop. As a rule, however, these requirements are found only under
+certain conditions and are ordinarily found only in manure heaps or in
+privy vaults or latrines. All observers agree that the female fly
+prefers to deposit her eggs in horse manure when this can be found and
+when this is piled in heaps in the barn-yard (Fig. 48) or in the field
+the heat caused by the decay and fermentation makes ideal conditions for
+the development of the larvae. Cow manure may serve as a breeding-place
+to a limited extent. The flies are immediately attracted to human
+excrement and breed freely in it when opportunity offers. Decaying
+vegetables or fruit, fermenting kitchen refuse and other materials
+sometimes also serve as breeding-places.
+
+In suitable places in warm weather the eggs will hatch in from eight to
+twelve hours and the larvae will become fully developed in from eight to
+fourteen days. They then change to pupae (Fig. 50) in which stage they
+may remain for another eight to twenty days when the adult flies will
+emerge. These figures must necessarily be indefinite because the weather
+and other conditions always vary. Under the most favorable conditions of
+moisture and temperature it is probably never less than eight days from
+egg to adult fly and under unfavorable conditions it may be as long as
+six weeks.
+
+The larvae thrive best when the manure is kept quite wet. I have often
+found them in almost incredible numbers in stables that had not been
+cleaned for some time. The horses standing there at night added fresh
+material and kept it just wet enough to make conditions almost ideal
+(Fig. 49).
+
+The pupae are usually found where the manure is a little dryer, but it
+must not be too dry. When the flies issue from the pupae they push their
+way up to the surface where they remain for a short time and allow the
+body to harden and the wings to dry before they fly away to other manure
+or, as too often happens, to some near-by kitchen or restaurant or
+market place.
+
+[Illustration: FIG. 48--Barn-yard filled with manure. Millions of flies
+were breeding here and infesting all the near-by houses.]
+
+[Illustration: FIG. 49--Dirty stalls; the manure had not been removed
+for some days and the floor was covered with maggots.]
+
+Of course it is impossible for them to issue from this filth without
+more or less of it clinging to their bodies. Now if these flies would
+breed only in barn-yard manure and fly directly from the stable to the
+house there would be comparatively little reason to complain, at least
+from a sanitary standpoint, for the amount of barn-yard filth that they
+carried to our food would be of little consequence. But when they breed
+in privy vaults or similar places, or visit such places before coming
+into the house or dairy or market place the results may be much more
+serious.
+
+
+FLIES AND TYPHOID
+
+It has been abundantly demonstrated that the excrement or the urine of a
+typhoid patient may contain virulent germs for some time before he is
+aware that he has the disease, and it has been shown that the germs may
+be present for weeks or months, and in some cases even years after the
+patient has recovered. If a fly breeds in such infected material, or
+feeds or walks on it, it is very apt to get some of the germs on its
+body where they may retain their virulence for some time, and should it
+visit our food while covered with these germs some of them would
+probably be left there where they might produce serious results. More
+than that. If the fly should feed on such infected material the typhoid
+germs would go on developing in the intestine of the fly and would be
+passed out with the feces in which they retain their virulence for some
+days. In other words, the too familiar "fly-specks" are not only
+disgusting, but may be a very grave source of danger. It will be seen
+that in this way several members of a community might become infected
+with the typhoid germs before anyone was aware that there was a case of
+typhoid or a "bacillus carrier" in the neighborhood.
+
+One more example out of the scores that might be cited to show how the
+fly may carry typhoid germs. They may enter the sick chamber in the home
+or in the hospital and there gain access to the typhoid germs. These
+they may carry to other parts of the house or to near-by houses, or the
+flies may light on passing carriages or cars and be carried perhaps for
+miles before they enter another house and contaminate the food there.
+
+These are hypothetical cases, but they illustrate what is taking place
+hundreds of times every season all over the world wherever typhoid fever
+and flies occur, and no country or race is known to be immune from
+typhoid, and the fly is found "wherever man is found."
+
+In the summer of 1898 a commission was appointed to investigate the
+prevalence of typhoid fever in the United States Army Concentration
+Camps. The following are some of the conclusions as reported by Dr.
+Vaughan:
+
+     "FLIES UNDOUBTEDLY SERVED AS CARRIERS OF THE INFECTION
+
+     "My reasons for believing that flies were active in the
+     dissemination of typhoid may be stated as follows:
+
+     "_a._ Flies swarmed over infected fecal matter in the pits and then
+     visited and fed upon the food prepared for the soldiers at the mess
+     tents. In some instances where lime had recently been sprinkled
+     over the contents of the pits, flies with their feet whitened with
+     lime were seen walking over the food.
+
+     "_b._ Officers whose mess tents were protected by means of screens
+     suffered proportionately less from typhoid fever than did those
+     whose tents were not so protected.
+
+     "_c._ Typhoid fever gradually disappeared in the fall of 1898, with
+     the approach of cold weather, and the consequent disabling of the
+     fly.
+
+     "It is possible for the fly to carry the typhoid bacillus in two
+     ways. In the first place, fecal matter containing the typhoid germ
+     may adhere to the fly and be mechanically transported. In the
+     second place, it is possible that the typhoid bacillus may be
+     carried in the digestive organs of the fly and may be deposited
+     with its excrement."
+
+In Dr. Daniel D. Jackson's report to the Merchants' Association of New
+York on the "Pollution of New York Harbor as a Menace to the Health by
+the Dissemination of Intestinal Diseases Through the Agency of the
+Common House-fly," he shows graphically that the prevalence of typhoid
+and other intestinal diseases is coincident with the prevalence of
+flies, and that the greatest number of deaths from such diseases occurs
+near the river front where the open or poorly constructed sewers scatter
+the filth where the flies can feed on it, or along the wharves with
+their inadequate accommodations and the resulting accumulation of filth.
+
+
+FLIES AND OTHER DISEASES
+
+Not only is the house-fly an important factor in the dissemination of
+typhoid fever, but it has been definitely shown that it is capable of
+transmitting several other serious diseases.
+
+The evidence that flies carry and spread the deadly germs of cholera is
+most conclusive. The germs may be carried on the body where they will
+live but a short time, or they may be carried in the alimentary canal
+where they will live for a much longer period and are finally deposited
+in the fly-specks where they retain their virulence for some time. Flies
+that had been allowed to contaminate themselves with cholera germs were
+allowed access to milk and meat. In both cases hundreds of colonies of
+the germs could later be recovered from the food. As with the typhoid
+germs milk seems to be a particularly good medium for the development of
+the cholera germs. In several of the experiments that have been made
+along this line the milk has been readily infected by the flies visiting
+it.
+
+Of course an outbreak of cholera is of rare occurrence in our country,
+but unfortunately this is not so in regard to some other intestinal
+diseases such as diarrhea and enteritis which annually cause the death
+of many children, especially bottle-fed babies. Those who have made
+close studies of the way in which these diseases are disseminated are
+convinced that the flies are one of the most important factors in their
+spread.
+
+It has long been observed that flies are particularly fond of sputum and
+will feed on it on the sidewalk, in the gutter, the cuspidor or wherever
+opportunity offers. It is well known, too, that the sputum of a
+consumptive contains myriads of virulent tubercular germs. A fly feeding
+and crawling over such material must necessarily get some of it on its
+body, and as it dries and the insect flies about the germs will be
+distributed through the air, possibly over our food. It has been shown
+that the excretion from a fly that has fed on tubercular sputum contains
+tubercular bacilli that may remain virulent for at least fifteen days.
+Thus we see again the danger that may lurk in the too familiar
+"fly-specks."
+
+Although it is generally supposed that the flea is solely responsible
+for the spread of the bubonic plague and no doubt is the principal
+distributing agent, the fact must not be overlooked that the house-fly
+may also be of considerable importance in this connection. Carefully
+planned experiments have shown that flies that have become infected by
+being fed on plague-infected material may carry the germs for several
+days and that they may die of the disease. During plague epidemics flies
+may become infected by visiting the sores on human or rat victims or by
+feeding on dead rats or on the excreta of sick patients, and an infected
+fly is always a menace should it visit our food or open wounds or sores.
+Anthrax bacilli are carried about and deposited by flies showing the
+possibility of the disease being spread in this way.
+
+Some believe that leprosy, smallpox and many other diseases are carried
+by the house-fly, so it is little wonder that it is fast losing its
+standing as a household companion and that we are beginning to regard it
+not only as a nuisance but as a source of danger which should no longer
+be tolerated in any community.
+
+Of course only a small per cent of the flies that visit our food in the
+dairies or market places or kitchens actually carry dangerous diseases,
+but they are all bred in filth and it is not possible without careful
+experiments or laboratory analysis to determine whether any of the germs
+among the millions that are on their bodies are dangerous or not. The
+chances that they may be are too great. The only safe way is to banish
+them all or to see that all of our food is protected from them.
+
+
+FIGHTING FLIES
+
+Screens and sticky fly-paper have their places and give some little
+relief in a well-kept house. But of what use is it to protect your food
+after it has entered your home if in the stores, in the market place, in
+the dairy barn, or dairy wagon, in the grocers' and butchers' cart, it
+has been exposed to contamination by hundreds of flies that have visited
+it.
+
+The problem is a larger one than keeping the house free from flies;
+larger but not more difficult, for the remedy is simple, effective,
+practicable and inexpensive. Destroy their breeding-places and you will
+have no flies. As the flies breed principally in manure the first
+remedial measure is to see that all manure is removed from the
+barn-yard at least once a week and spread over the fields to dry, for
+the flies cannot breed in the dry manure. If it is not practicable to
+remove it this often the manure should be kept in a bin that is closed
+so tight that no flies can get into it to lay their eggs. Sometimes the
+manure may be treated with some substance such as kerosene, crude oil,
+chlorid of lime, tobacco water or mixture of two or more of these and
+thus rendered unsuitable for the flies to breed in, but in general
+practice none of them has been found very satisfactory for the treatment
+is either not thorough enough or is too expensive of time and material.
+
+Outdoor privies and cesspools must be carefully attended to. The latter
+can be easily covered so no flies can get in and if the filthy and in
+every way dangerous pit under the privy be filled and the dry-earth
+closet substituted one of the greatest sources of danger, especially in
+the country and in towns with inadequate sewerage facilities, will be
+done away with. After these things are done there remain only the
+garbage cans and the rubbish heaps to look after.
+
+Of course your neighbor must keep his place clean too, for his flies are
+just as apt to come into your house as his, so the problem becomes one
+for the whole community.
+
+Almost all cities and many of the smaller towns have ordinances which
+if enforced would afford adequate protection from flies, but they are
+seldom if ever rigidly enforced and it yet remains for some enterprising
+town to be able to advertise itself as a "speckless town" as well as a
+"spotless town."
+
+
+AN EXPERT'S OPINION
+
+In a recent important bulletin issued by the Bureau of Entomology, Dr.
+L.O. Howard discusses the economic importance of several of the insects
+that carry disease. I wish to quote two or three paragraphs from the
+pages in which he discusses the house-fly or typhoid fly to show the
+opinion of this excellent authority in regard to this pest.
+
+     "Even if the typhoid or house fly were a creature difficult to
+     destroy, the general failure on the part of communities to make any
+     efforts whatever to reduce its numbers could properly be termed
+     criminal neglect; but since, as will be shown, it is comparatively
+     an easy matter to do away with the plague of flies, this neglect
+     becomes an evidence of ignorance or of a carelessness in regard to
+     disease-producing filth which to the informed mind constitutes a
+     serious blot on civilized methods of life."
+
+On another page:
+
+     "We have thus shown that the typhoid or house fly is a general and
+     common carrier of pathogenic bacteria. It may carry typhoid fever,
+     Asiatic cholera, dysentery, cholera morbus, and other intestinal
+     diseases; it may carry the bacilli of tuberculosis and certain eye
+     diseases. It is the duty of every individual to guard so far as
+     possible against the occurrence of flies upon his premises. It is
+     the duty of every community, through its board of health, to spend
+     money in the warfare against this enemy of mankind. This duty is as
+     pronounced as though the community were attacked by bands of
+     ravenous wolves."
+
+Again:
+
+     "A leading editorial in an afternoon paper of the city of
+     Washington, of October 20, 1908, bears the heading, 'Typhoid a
+     National Scourge,' arguing that it is to-day as great a scourge as
+     tuberculosis. The editorial writer might equally well have used the
+     heading 'Typhoid a National Reproach,' or perhaps even 'Typhoid a
+     National Crime,' since it is an absolutely preventable disease. And
+     as for the typhoid fly, that a creature born in indescribable filth
+     and absolutely swarming with disease germs should practically be
+     invited to multiply unchecked, even in great centers of population,
+     is surely nothing less than criminal."
+
+The whole bulletin (No. 78, Bureau of Entomology) should be read and
+studied by all who are interested in this subject.
+
+
+OTHER FLIES
+
+Occasionally other flies looking more or less like the house-fly are
+seen in houses. Some of these have the same type of sucking mouth-parts
+and have habits very similar to the house-fly, but as they are usually
+much less common and as nearly all that has been said in regard to the
+house-fly would apply equally well to them and as the same measures
+should be adopted in fighting them they need not be discussed further
+here.
+
+I have already called attention to the fact that a fly which looks very
+much like the house-fly is sometimes found in the house and will often
+bite severely. It has quite a different style of beak, one that is
+fitted for piercing so it may suck the blood of its victim (Fig. 51). As
+these flies often seem to be more persistent before a rain the weather
+prophet will tell you that "It is surely going to rain for the
+house-flies are beginning to bite."
+
+These stable-flies, as they are called, are great pests of cattle and
+horses in some sections. It is thought that they are important factors
+in the spread of some of the diseases of domestic animals, and their
+habit of sometimes attacking human beings makes it possible for them to
+carry certain disease germs from animals to man or from man to man.
+
+
+
+
+CHAPTER VI
+
+MOSQUITOES
+
+
+Mosquitoes are no more abundant now than they have been in the past, but
+when Linnaeus in 1758 made his list of all the animals known to exist at
+that time he catalogued only six species of mosquitoes. Only a few years
+ago, 1901, Dr. Theobald of the British Museum published a book on the
+mosquitoes of the world in which he listed three hundred and forty-three
+kinds. Soon other volumes appeared, adding more species, and
+systematists everywhere have been describing new ones until now the
+total number of described species is probably over five hundred, more
+than sixty of which occur in the United States.
+
+This shows only one phase of the great interest that has been taken in
+the mosquitoes since the discovery of their importance as carriers of
+disease. Not only have they been studied from a systematic standpoint
+but an endless amount of work has been done and is being done in
+studying their development, habits, and structure until now, if one
+could gather together all that has been written about mosquitoes in the
+last ten or twelve years he would have a considerable library.
+
+[Illustration: FIG. 50--Pupa of house-fly with the end broken to allow
+the fly to issue.]
+
+[Illustration: FIG. 51--Head of stable-fly showing sharp piercing beak.]
+
+[Illustration: FIG. 52--Mass of mosquito eggs (_Theobaldia incidens_).]
+
+[Illustration: FIG. 53--Mosquito eggs and larvae (_Theobaldia
+incidens_); two larvae feeding on bottom, others at surface to breathe.]
+
+[Illustration: FIG. 54--Mosquito larvae (_T. incidens_), dorsal view.]
+
+Those who are particularly interested in the group will find some of
+these books and papers easily accessible, so there may be given here
+only a brief summary of the more important facts in regard to the
+structure and habits of the mosquitoes in order that we may more readily
+understand the part that they play in the transmission of diseases and
+see the reasonableness of the recommendations in regard to fighting
+them.
+
+
+THE EGGS
+
+Mosquito eggs are laid in water or in places where water is apt to
+accumulate, otherwise they will not hatch. Some species lay their eggs
+in little masses (Fig. 52) that float on the surface of the water,
+looking like small particles of soot. Others lay their eggs singly, some
+floating about on the surface, others sinking to the bottom where they
+remain until the young issue. Some of the eggs may remain over winter,
+but usually those laid in the summer hatch in thirty-six to forty-eight
+hours or longer according to the temperature.
+
+
+THE LARVAE
+
+When the larvae are ready to issue they burst open the lower end of the
+eggs and the young wrigglers escape into the water. The larvae are fitted
+for aquatic life only, so mosquitoes cannot breed in moist or damp
+places unless there is at least a small amount of standing water there.
+A very little will do, but there must be enough to cover the larvae or
+they perish.
+
+The head of the larvae of most species is wide and flattened. The eyes
+are situated at the sides, and just in front of them is a pair of short
+antennae which vary with the different species.
+
+The mouth-parts too vary greatly according to the feeding habits. Some
+mosquito larvae are predaceous, feeding on the young of other species or
+on other insects. These of course have their mouth-parts fitted for
+seizing and holding their prey. Most of the wrigglers, however, feed on
+algae, diatoms, Protozoa and other minute plant or animal forms which are
+swept into the mouth by curious little brush-like organs whose movements
+keep a stream of water flowing toward the mouth.
+
+Another group containing the _Anopheles_ are intermediate between these
+two and have mouth-parts fitted for feeding on minute organisms as well
+as for attacking and holding other larger things.
+
+[Illustration: FIG. 55--Eggs, larvae and pupae of mosquitoes (_T.
+incidens_).]
+
+[Illustration: FIG. 56--Larva of mosquito (_T. incidens_).]
+
+[Illustration: FIG. 57--Mosquito larvae and pupae (_T. incidens_) with
+their breathing-tubes at the surface of the water.]
+
+[Illustration: FIG. 58--Anopheles larvae (_A. maculipennis_) resting at
+the surface of the water.]
+
+A few kinds feed habitually some distance below the surface, others on
+the bottom, while still others feed always at the surface. With one or
+two exceptions, the larvae must all come to the surface to breathe (Figs.
+53-57). Most species have on the eighth abdominal segment a rather long
+breathing-tube the tip of which is thrust just above the surface of the
+water when they come up for air. In this tube are two large vessels or
+tracheae which open just below the tip of the tube and extend forward
+through the whole length of the body, giving off branches here and there
+that divide into still smaller branches until every part of the body is
+reached by some of the small divisions of this tracheal system that
+carries the oxygen to all the tissues. The length of the breathing-tube
+is correlated with the feeding-habits of the larvae. _Anopheles_ larvae
+which feed at the surface have very short tubes (Fig. 58), others that
+feed just below the surface have breathing-tubes as long or very much
+longer than the ninth abdominal segment. The last segment has at its tip
+four thin flat plates, the tracheal gills. These too are larger or
+smaller according to the habits of the larvae. Those species that feed
+close to the surface and have the tip of the breathing-tube above the
+surface most of the time have very small tracheal gills, while those
+that feed mostly on the bottom have them well developed.
+
+When first hatched the larvae are of course very small. If the weather is
+warm and the food is abundant they grow very rapidly. In a few days the
+outer skin becomes rather firm and inelastic so it will not allow
+further growth. Then a new skin forms underneath and the old skin is
+cast off. This process of casting off the old skin is called molting,
+and is repeated four times during the one, two, three or more weeks of
+larval life.
+
+
+PUPA
+
+With the fourth molt the active feeding larva changes to the still
+active but non-feeding pupa (Fig. 59). The head and thorax are closely
+united and a close inspection will reveal the head, antennae, wings and
+legs of the adult mosquito folded away beneath the pupal skin. Instead
+of the breathing-tube on the eighth segment of the abdomen as in the
+larva, the pupa has two trumpet-shaped tubes on the back of the thorax
+through which it now gets its air from above the surface. The pupal
+stage lasts from two to five or six days or more. When the adult is
+ready to issue the pupal skin splits along the back and the mosquito
+gradually and slowly issues. It usually takes several minutes for the
+adult to issue and for its wings to become hard enough so it can fly. In
+the meantime, it is resting on the old pupal skin or on the surface of
+the water, where it is entirely at the mercy of any of its enemies that
+might happen along and is in constant danger of being tumbled over
+should the water not be perfectly smooth.
+
+[Illustration: FIG. 59--Mosquito pupae (_T. incidens_) resting at the
+surface of the water.]
+
+[Illustration: FIG. 60--Mosquito pupa (_T. incidens_) with its
+breathing-tubes in an air bubble below the surface of the water.]
+
+[Illustration: FIG. 61--Mosquito larvae and pupae (_T. incidens_) resting
+at the surface of the water.]
+
+[Illustration: FIG. 62--A female mosquito (_T. incidens_); note the
+thread-like antennae.]
+
+[Illustration: FIG. 63--A male mosquito (_T. incidens_); note the
+feathery antennae.]
+
+
+THE ADULT
+
+The adult mosquito is altogether too familiar an object to need
+description, but it is necessary that we keep in mind certain particular
+points in regard to its structure, in order that we may better
+understand how it is that it is capable of transmitting disease.
+
+If we examine closely the antennae of a number of mosquitoes that are
+bothering us with their too constant attentions we shall see that they
+all look very much alike (Fig. 62), small cylindrical joints bearing
+whorls of short fine hairs. But if we examine a number of mosquitoes
+that have been bred from a jar or aquarium we will find two types of
+antennae, the one described above belonging to the female. The antennae of
+the male (Fig. 63) are much more conspicuous on account of the whorl of
+dense, fine, long hairs on each segment. Another interesting difference
+in the antennae is to be noted in the size of the first joint. In both
+sexes it is short and cup-shaped, but in the male it is somewhat larger.
+This basal segment contains a highly complex auditory organ which
+responds to the vibrations of the whorls of hairs on the other segments.
+Interesting experiments have shown that these hairs vibrate best to the
+pitch corresponding to middle C on the piano, the same pitch in which
+the female "sings." Of course mosquitoes and other insects have no voice
+as we ordinarily understand the word, but produce sound by the rapid
+vibration of the wings or by the passage of air through the openings of
+the tracheae. The males and females are thus easily distinguished and, as
+we shall see later, this is of some importance for only the females can
+bite. The males and females differ in another way. Just below the
+antennae and at the sides of the proboscis or beak is a pair of three-to
+five-jointed appendages, the maxillary palpi or mouth-feelers which in
+the females of most species are very short (Fig. 64) while in the males
+they are usually as long as the proboscis (Fig. 65). The females of
+_Anopheles_ and related forms have palpi quite as long as the males, but
+they are slender throughout while the male palpi are usually somewhat
+enlarged toward the tip and bear more or less conspicuous patches of
+rather long hairs or scales.
+
+[Illustration: FIG. 64--Head and thorax of female mosquito
+(_Ochlerotatus lativittatus_); the short maxillary palpi are just above
+the proboscis and below the thread-like antennae.]
+
+[Illustration: FIG. 65--Head and thorax of male mosquito (_O.
+lativittatus_); the maxillary palpi are as long as the proboscis.]
+
+[Illustration: FIG. 66--Head of female mosquito (_Anopheles_), with
+mouth-parts separated to show the needle-like parts: _a_, _a_ antennae;
+_b_, _b_, palpi; _c_, labrum; _d_, _d_, mandibles; _e_, hypopharynx;
+_f_, _f_, maxillae; _g_, labium; _h_, labella. (After Manson.)]
+
+[Illustration: FIG. 67--Cross-section of proboscis of female (_a_) and
+male (_b_) mosquito. _lxe_, labrum-epipharynx; _mn_, mandibles; _mx_,
+maxillae; _hp_, hypopharynx; _sal_, salivary duct; _li_, labium; _tr_,
+trachea; _mus_, muscles. (After Nuttall and Shipley.)]
+
+
+THE MOUTH-PARTS
+
+The mouth-parts of the mosquito are of course of particular interest to
+us. At first they appear to consist of a long slender beak or proboscis,
+but by dissecting and examining with a microscope we find this beak to
+be made up of several parts (Fig. 66). The labium, which is the largest
+and most conspicuous, is apparently cylindrical but is grooved above
+throughout its length. At the tip of the labium are the labellae, two
+little lobes which serve to guide the piercing organs. Lying in this
+groove along the upper side of the labium are six very fine,
+sharp-pointed needles. The uppermost of these, the labrum-epipharynx, or
+labrum as we will call it, is the largest and is really a hollow tube
+very slightly open on its under side. Just below this is the
+hypopharynx, the lateral margins of which are very thin. Down through
+the median line of the hypopharynx runs a minute duct (Fig. 67, sal)
+which, though exceedingly small, is of very great importance, for
+through it is poured the saliva which may carry the malaria germs into
+the wound made when the mosquito bites. The other four needles consist
+of a pair of mandibles which are lance-shaped at the tip and a heavier
+pair of maxillae, the tips of which are serrate on one edge.
+
+
+HOW THE MOSQUITO BITES
+
+When the female mosquito is feeding on man or any other animal the tip
+of the labium is placed against the surface and the six needles are
+thrust into the skin, the labellae serving as guides. As they are thrust
+deeper and deeper the labium is bowed back to allow them to enter. As
+soon as the wound is made the insect pours out through the tube of the
+hypopharynx some of the secretion from the salivary glands and then
+begins to suck up the blood through the hollow labrum into the pharynx
+and on into the stomach.
+
+The mouth-parts of the male differ in some important respects from those
+of the female. The hypopharynx is united to the labium, the mandibles
+are wanting and the maxillae are very much reduced so that the insect is
+unable to pierce the tough skin of animals. The male feeds on the juices
+of plants as do the females when they cannot get blood. It is not at all
+necessary for mosquitoes to have the warm blood of man or other animals.
+Comparatively few of them ever taste blood. They have been seen feeding
+on blossoms, ripe fruit, watermelons, plant juices, etc. They are very
+fond of ripe bananas and are fed on them in the laboratory when we wish
+to keep mosquitoes for experimental purposes.
+
+
+THE THORAX
+
+The middle part of the body, called the thorax, is really a strong box
+with heavy walls for the attachment of the powerful wing and leg
+muscles. The three pairs of legs are covered with hairs and scales, and
+their tips are provided with a pair of claws which vary somewhat in the
+different species. The wings (Fig. 68) are long and narrow with a
+characteristic venation. Along the veins and the margin of the wings are
+the scales which readily enable one to distinguish mosquitoes from other
+insects that may look much like them. In some species these scales are
+long and narrow, almost hair-like, in others they are quite broad and
+flat (Fig. 69). Just back of the wings is a pair of balancers, short
+thread-like processes knobbed at the end. These probably represent the
+second pair of wings with which most insects are provided, and seem to
+serve as balancers or orienting organs when the insect is flying. On the
+sides of the thorax are two small slit-like openings, the
+breathing-pores. These are the openings into the tracheal or respiratory
+system.
+
+
+THE ABDOMEN
+
+The long cylindrical abdomen is composed of eight segments. These are
+rather strongly chitinized above and below, but a narrow strip along the
+side is unchitinized. In this strip are situated the abdominal
+breathing-pores. The tip of the abdomen is furnished with a pair of
+movable organs, which in the male are variously modified and serve as
+clasping organs at mating time.
+
+
+THE DIGESTIVE SYSTEM
+
+The mouth-parts of the mosquito have just been described. It will be
+remembered that the labrum is provided with a groove. Through this the
+blood or other food is sucked up by means of a strong-walled pumping
+organ, the pharynx, situated in the head (Fig. 70). Just back of the
+pharynx is the esophagus which leads to the beginning of the stomach.
+Close to its posterior end the esophagus gives off three food
+reservoirs, two above and a single larger one below. In dissections
+these will often be seen to be filled with minute bubbles. The stomach
+reaches from the middle of the thorax to beyond the middle of the
+abdomen. At its posterior end are given off five long slender processes,
+the Malpighian tubules which are organs of excretion, acting like the
+kidneys of higher animals. The hindgut is that portion of the intestine
+from the stomach to the end of the body.
+
+[Illustration: FIG. 68--Wing of Mosquito (_O. lativittatus_).]
+
+[Illustration: FIG. 69--End of mosquito wing highly magnified to show
+the scales on the veins.]
+
+[Illustration: FIG. 70--Diagram to show the alimentary canal and
+salivary glands of a mosquito.]
+
+[Illustration: FIG. 71--Salivary glands of _Culex_ at right. _Anopheles_
+at left. (After Christophers.)]
+
+
+THE SALIVARY GLANDS
+
+Lying under the alimentary canal in the forward part of the thorax are
+the salivary glands. There are two sets of these, each having three
+lobes with a common duct which joins the duct from the other set a short
+distance before they enter the base of the hypopharynx. Each of these
+lobes is made up of a layer of secreting cells (Fig. 71) which produces
+the saliva that is poured into the wound as soon as the insect pierces
+the skin of the victim, and we shall see, too, that the malarial germs
+also collect in these glands to be carried by the saliva to the new
+host.
+
+
+EFFECTS OF THE BITE
+
+After a mosquito has bitten a person and withdrawn the stylets, a small
+area about the puncture whitens, then soon becomes pink and begins to
+swell, then to itch and burn. Some people suffer much more from the
+bites of mosquitoes than do others. For some such bites mean little or
+no inconvenience, indeed may pass wholly unnoticed, to others a single
+bite may mean much annoyance, and several bites may cause much
+suffering.
+
+After an hour or so the itching usually ceases, but in some cases it
+continues longer. In some instances little or no irritation is felt
+until some hours, sometimes as much as a day, after the bite. In such
+cases the effect of the bite is apt to be severe and to last for several
+days. Sometimes a more or less serious sore will follow a bite, probably
+due to infection of the wound by scratching. It is doubtless the saliva
+that is poured into the wound that causes the irritation. It is
+frequently asserted that if the mosquito is allowed to drink its fill
+and withdraw its beak without being disturbed no evil results will
+follow. Those who hold this theory say that the saliva that is poured
+into the wound is all withdrawn again with the blood if the mosquito is
+allowed to feed long enough. There may be some truth in this, but for
+most of us a bite means a hurt anyway and few will be content to sit
+perfectly still and watch the little pest gradually fill up on blood.
+
+It is not known just what the action of the saliva is, its composition
+or reaction on the tissues. It is generally supposed to prevent
+coagulation of the blood that is to be drawn through the narrow tube of
+the labrum. Others think that its presence causes a greater flow of
+blood to the wound. But the sad part of it is, for us at least, that it
+hurts and may cause malaria and possibly other diseases.
+
+
+HOW MOSQUITOES BREATHE
+
+Mosquitoes and other insects do not have any nostrils nor do they
+breathe through any openings on the head. Along the sides of the thorax
+and abdomen is a series of very minute openings known as the spiracles.
+Through these the air passes into a system of air-tubes, the tracheae.
+There are two main trunks or divisions of the tracheae just inside the
+body-wall and a number of shorter connecting trunks. From these larger
+vessels arise a great number of smaller ones which branch and subdivide
+again and again until all the tissues are supplied by these minute
+little air-tubes that carry the oxygen to all parts of the body and
+carry off the waste carbon dioxid. These air-tubes are emptied and
+filled by the contractions of the walls of the abdomen. When the
+body-wall contracts the air is forced out of the thin-walled trachea
+through the spiracles; when the pressure is removed they are refilled by
+the fresh air rushing in.
+
+
+THE BLOOD
+
+After a mosquito has been feeding on a man or some other animal it is
+often so distended that the blood shows rich and red through the thin
+sides of the walls of the abdomen. This, however, is the blood of the
+victim and not of the mosquito. The blood of insects is not red but pale
+yellowish or greenish. It is not confined in definite vessels, but fills
+all the space inside the body cavity that is not occupied by some of the
+tissues or organs. It bathes the walls of the alimentary canal and
+gathers there the nourishment which it carries to all parts of the body.
+It does not carry oxygen or collect the carbon dioxid as does the blood
+of higher animals. That work, as we have just seen, is done by the
+air-tubes. Above the alimentary canal, extending almost the whole length
+of the abdomen and thorax, is a thin-walled pulsating vessel, the heart.
+This consists of a series of chambers each communicating with the one in
+front of it by an opening which is guarded by a valve. When one of these
+chambers contracts it forces the blood that is in it forward into the
+next chamber which, in its turn, sends it on. As the walls relax the
+valves at the sides are opened and the blood that is in the body-cavity
+rushes in to fill the empty chamber. As these regular rythmical
+pulsations recur the blood is forced forward through the heart into the
+head where it bathes the organs there. We shall see in another chapter
+that the malarial parasite escapes from the walls of the stomach of the
+mosquito into the blood in the body-cavity and finally reaches the
+salivary glands. As the heart is constantly driving blood to this part
+of the body the parasites readily reach the glands from which they
+finally escape into the new host.
+
+[Illustration: FIG. 72--Heads of Culicinae mosquitoes; _a_, male; _b_,
+female. (After Manson.)]
+
+[Illustration: FIG. 73--Heads of Anophelinae mosquitoes; _c_, male; _d_,
+female. (After Manson.)]
+
+[Illustration: FIG. 74--Wing of _Anopheles maculipennis_.]
+
+[Illustration: FIG. 75--Wing of _Theobaldia incidens_.]
+
+[Illustration: FIG. 76--A non-malarial mosquito (_T. incidens_), male,
+standing on the wall.]
+
+[Illustration: FIG. 77--Female of same.]
+
+[Illustration: FIG. 78--A malarial mosquito (_A. maculipennis_), male,
+standing on the wall.]
+
+[Illustration: FIG. 79--Female of same.]
+
+
+CLASSIFICATION
+
+For our purpose it will not be necessary to try to give a system of
+classification of all the mosquitoes. Those interested in this phase of
+the subject will find several books and papers devoted wholly to it. It
+is quite important, however, that we know something about a few of the
+more familiar groups and kinds, especially those concerned in the
+transmission of diseases.
+
+
+THE ANOPHELES
+
+In pointing out the differences between male and female mosquitoes we
+noted that in one group, the genus _Anopheles_, both sexes have long
+maxillary palpi (Figs. 72, 73). This is the most important character
+separating this genus from the other common forms and as the
+_Anopheles_ are the malaria carriers it is important that this
+difference be remembered. Most of the members of this group have spotted
+wings (Fig. 74), but as some other common kinds also have spotted wings
+(Fig. 75) this character will not always be reliable. When an
+_Anopheles_ mosquito is at rest the head and proboscis are held in one
+line with the body and the body rests at a considerable angle to the
+surface on which it is standing. Other kinds rest with the body almost
+or quite parallel to the surface on which they are standing. So if you
+find a female mosquito with long mouth-palpi and spotted wings resting
+at an angle to the surface on which it stands you may be reasonably sure
+that it is an _Anopheles_ and therefore may be dangerous (Figs. 76, 77,
+78, 79).
+
+In the United States there are three species of
+_Anopheles_--_maculipennis_, _punctipennis_ and _crucians_--which are
+common in various localities, and one or two other species that so far
+as known are local or rare.
+
+The _Anopheles_ eggs are not laid in masses as are the eggs of many
+other mosquitoes, but are deposited singly on the surface of the water
+where they may be found often floating close together.
+
+[Illustration: FIG. 80--Egg of Anopheles, side view. (After Nuttall and
+Shipley.)]
+
+[Illustration: FIG. 81--Egg of Anopheles, dorsal view. (After Nuttall
+and Shipley.)]
+
+[Illustration: FIG. 82--Anopheles larvae, the one to the right feeding.]
+
+[Illustration: FIG. 83--Anopheles larvae, the one to the right feeding,
+the other just coming to the surface.]
+
+[Illustration: FIG. 84--Anopheles larva, dorsal view.]
+
+[Illustration: FIG. 85--Anopheles pupae resting at surface of water.]
+
+The eggs (Figs. 80, 81) are elliptical in outline and are provided with
+a characteristic membranous expansion near the middle.
+
+The larvae may be found at the proper season and in the localities where
+they are abundant in almost any kind of standing water, in clear little
+pools beside running streams, in the overflow from springs, in swamps
+and marshy lands, in rain-barrels or any other places or vessels where
+the water is quiet. They do not breed in brackish water. As they feed
+largely on the algae or green scum on the surface of the water they are
+especially apt to be found where this is present. We have already noted
+that their positions in the water differ from that assumed by other
+species (Fig. 82).
+
+As the breathing-tube is very short the larvae must come close to the
+surface to breathe, and when they are feeding we find them lying just
+under and parallel to the surface of the water with their curious round
+heads turned entirely upside down as they feed on the particles that are
+floating on the surface (Figs. 83, 84).
+
+The pupae do not differ very much from the pupae of other species although
+the breathing-tubes on the thorax are usually shorter and the creature
+usually rests with its abdomen closer to the surface, that is, it does
+not hang down from the surface quite as straight as do other forms (Fig.
+85).
+
+The adults may be found out of doors or in houses, barns or other
+outbuildings. They do not seem to like a draft and consequently will be
+more apt to frequent rooms or places where there is little circulation
+of air. Although they are usually supposed to fly and bite only in the
+evening or at night, they may occasionally bite in the daytime. One
+hungry female took two short meals from my arm while we were trying to
+get her to pose for a photograph one warm afternoon.
+
+The female passes the winter in the adult condition, hibernating in any
+convenient place about old trees or logs, in cracks or crevices in doors
+or out of doors. In the house they hide in the closets, behind the
+bureau, behind the head of the bed, or underneath it, or in any place
+where they are not apt to be disturbed. During a warm spell in the
+winter or if the room is kept warm they may come out for a meal almost
+any time.
+
+
+THE YELLOW FEVER MOSQUITO
+
+Ranking next in importance to _Anopheles_ as a disseminator of disease
+and in fact solely responsible for a more dreaded scourge, is the
+species of mosquito now known as _Stegomyia calopus_. While this species
+is usually restricted to tropical or semi-tropical regions it sometimes
+makes its appearance in places farther north, especially in summer
+time, where it may thrive for a time. The adult mosquito (Fig. 104) is
+black, conspicuously marked with white. The legs and abdomen are banded
+with white and on the thorax is a series of white lines which in
+well-preserved specimens distinctly resembles a lyre. These mosquitoes
+are essentially domestic insects, for they are very rarely found except
+in houses or in their immediate vicinity. Once they enter a room they
+will scarcely leave it except to lay their eggs in a near-by cistern,
+water-pot, or some other convenient place.
+
+Their habit of biting in the daytime has gained for them the name of
+"day mosquitoes" to distinguish them from the night feeders. But they
+will bite at night as well as by day and many other species are not at
+all adverse to a daylight meal, if the opportunity offers, so this habit
+is not distinctive. The recognition of these facts has a distinct
+bearing in the methods adopted to prevent the spread of yellow fever.
+There are no striking characters or habits in the larval or pupal stages
+that would enable us to distinguish without careful examination this
+species from other similar forms with which it might be associated. For
+some time it was claimed that this species would breed only in clean
+water, but it has been found that it is not nearly so particular, some
+even claiming that it prefers foul water. I have seen them breeding in
+countless thousands in company with _Stegomyia scutellaris_ and _Culex
+fatigans_ in the sewer drains in Tahiti in the streets of Papeete. As
+the larvae feed largely on bacteria one would expect to find them in
+exactly such places where the bacteria are of course abundant.
+
+The fact that they are able to live in any kind of water and in a very
+small amount of it well adapts them to their habits of living about
+dwellings.
+
+So far as known the members of these two genera are the only two that
+are concerned in the transmission of disease in the United States. In
+other countries other species are suspected or proven disseminators of
+certain diseases, but these will be discussed in connection with the
+particular diseases in later chapters.
+
+
+OTHER SPECIES
+
+The many other species of mosquitoes that we have may be conveniently
+divided as to their breeding-habits into the fresh-water and the
+brackish-water forms. Among the fresh-water kinds some are found
+principally associated with man and his dwelling places, others live in
+the woods or other places and so are far less troublesome. Most of
+these do not fly far. Several of the species that breed in brackish
+water are great travelers and may fly inland for several miles. Thus the
+towns situated from one to three or four miles inland from the lower
+reaches of San Francisco Bay are often annoyed more by the mosquitoes
+that breed only in the brackish water on the salt marshes than they are
+by any of the fresh-water forms (Figs. 86, 87). The worst mosquito pest
+along the coast of the eastern United States and for some distance
+inland is a species that breeds in the salt marshes.
+
+
+NATURAL ENEMIES OF MOSQUITOES
+
+In combating noxious insects we learned long ago that often the most
+efficient, the easiest and cheapest way is to depend on their natural
+enemies to hold them in check. Under normal or rather natural conditions
+we find that they are usually kept within reasonable bounds by their
+natural enemies, but under the artificial conditions brought about by
+the settling and developing of any district great changes come about. It
+very often happens that these changes are favorable to the development
+of the noxious insects and unfavorable to the development of their
+enemies.
+
+A striking example and one to the point is afforded in the introduction
+of mosquitoes into Hawaii. Up to 1826 there were no mosquitoes on these
+islands. It is supposed that they were introduced about that time by
+some ships that were trading at the islands. Indeed it is claimed that
+the very ship is known that brought them over from Mexico.
+
+Once introduced they found conditions there very favorable to their
+development, plenty of standing water and few natural enemies to prey on
+them, so they increased very rapidly and gradually spread over all the
+islands of the group. This was the so-called night mosquito, _Culex
+pipiens_. Much later another species, _Stegomyia calopus_, just as
+annoying and much more dangerous was introduced and has also become very
+troublesome. We have a few species of top-minnows (Fig. 88) occurring in
+sluggish streams in the southern part of the United States that are
+important enemies of the mosquitoes of that region. A few years ago some
+of these were taken over to Hawaii and liberated in suitable places to
+see if they would not help solve the mosquito problem there. The fishes
+seem to be doing well. Already they are destroying many mosquito larvae,
+and there are indications that they are going to do an important work,
+but of course can be depended on only as an aid.
+
+[Illustration: FIG. 86--Salt-marsh mosquito (_Ochlerotatus
+lativittatus_); male.]
+
+[Illustration: FIG. 87--Salt-marsh mosquito (_O. lativittatus_);
+female.]
+
+[Illustration: FIG. 88--Top-minnow (_Mollienisia latipinna_). (From
+Bull., 47 U.S. Fish Com.)]
+
+[Illustration: FIG. 89--Dragon-flies. (From Kellogg's Amer. Insects.)]
+
+On account of the various habits of both the larvae and adults it will
+never be possible for any natural enemy or group of natural enemies
+effectively to control the mosquitoes of any region, but as certain of
+them are important as helpers they deserve to be mentioned.
+
+
+ENEMIES OF THE ADULTS
+
+Birds devour a few mosquitoes, the night-flying forms being particularly
+serviceable, but the number thus destroyed is probably so small as to be
+of little practical importance.
+
+The dragon-flies (Figs. 89, 90, 91) or mosquito hawks have long been
+known as great enemies of mosquitoes, and they certainly do destroy many
+of them as they are hawking about places where mosquitoes abound. Dr.
+J.B. Smith of New Jersey very much doubts their efficiency, but
+observations made by other scientific men would seem to indicate that
+they often devour large numbers of mosquitoes during the course of the
+day and evening.
+
+Spiders and toads destroy a few mosquitoes each night. Certain external
+and internal parasites destroy a few more, but the sum total of all of
+these agencies is probably not very considerable, for while the adults
+may have several natural enemies they are not of sufficient importance
+to have any appreciable effect on the number of mosquitoes in a badly
+infested region.
+
+
+ENEMIES OF THE LARVAE AND PUPAE
+
+The larvae and pupae on the other hand have many important enemies. Indeed
+under favorable conditions these may keep small ponds or lakes quite
+free from the pests. The predaceous aquatic larvae of many insects feed
+freely on wrigglers. The larvae of the diving beetles which are known as
+water-tigers are particularly ferocious and will soon destroy all the
+wrigglers in ponds where they are present (Fig. 92). Dragon-fly larvae
+also feed freely on mosquito larvae. Whirligig beetles are said to be
+particularly destructive to _Anopheles_ larvae and many other insects
+such as water-boatmen, back-swimmers, etc., feed on the larvae of various
+species. A few of these introduced into a breeding-jar with _Anopheles_
+larvae will soon destroy all of them, even the very young bugs attacking
+larvae much larger than themselves.
+
+It is interesting to note that the larvae of some mosquitoes are
+themselves predaceous and feed freely on the other wrigglers that may
+chance to be in the same locality.
+
+[Illustration: FIG. 90--The young (nymph) of a dragon-fly. (From
+Kellogg's Amer. Insects.)]
+
+[Illustration: FIG. 91--The cast skin (exuvae) of a dragon-fly nymph.]
+
+[Illustration: FIG. 92--Diving-beetles and back-swimmers. (From
+Kellogg's Amer. Insects.)]
+
+Various species of fish are, however, the most important enemies of the
+mosquitoes. Great schools of tide-water minnows (Fig. 93) are often
+carried over the low salt-marshes by the extreme high-tides and left in
+the hundreds of tide pools as the tide recedes. No mosquitoes can breed
+in a pool thus stocked with these fish. In the fresh-water streams and
+lakes there are several species of the top-minnows, sticklebacks (Fig.
+94), etc., that feed voraciously on mosquito larvae and unless the grass
+or reeds prevent the fish from getting to all parts of the ponds or
+lakes very few mosquitoes can breed in places where they are present.
+
+Minute red mites such as attack the house-flies and other insects
+sometimes attack adult mosquitoes, but they are rarely very abundant.
+Parasitic roundworms attack certain species. Others suffer more or less
+from the attacks of various Sporozoan parasites.
+
+
+FIGHTING MOSQUITOES
+
+When mosquitoes are bothering us we usually begin by trying to kill the
+individual pests that are nearest to us. We try to crush them if they
+bite us; we screen the doors and windows to keep them from the house. In
+warmer countries the people are a little more hospitable and do not
+screen the mosquitoes out of the house entirely, but screen the beds for
+protection at night, and if the mosquitoes get too insistent during the
+day the bed makes a safe and comfortable retreat. All the mosquitoes in
+a room may be killed by fumigating with sulphur at the rate of two
+pounds to the thousand cubic feet of air-space. Pyrethrum is also used
+largely, but it only stupefies the mosquitoes temporarily instead of
+killing them. While in that condition they may be swept up and
+destroyed.
+
+Various substances are sometimes used as repellants by those who must be
+in regions where the mosquitoes are abundant. With many of these,
+however, "the cure is worse than the disease." Smudges are often built
+to the windward of a house or barn-yard and the smoke from a good
+smoldering fire will keep a considerable area quite free from
+mosquitoes. The man who can keep himself enveloped in a cloud of tobacco
+smoke will not be bothered by mosquitoes. Oil of pennyroyal, oil of tar
+or a mixture of these with olive oil, and various other concoctions are
+sometimes smeared over the face and hands. These will furnish protection
+as long as they last. Dr. Smith says that he has found oil of citronella
+quite effective and of course less objectionable than the other things
+usually used. Care should be taken not to get it in the eyes. An
+ointment made of cedar oil, one ounce; oil of citronella, two ounces;
+spirits of camphor, two ounces, is said to make a good repellant and is
+effective for a long time.
+
+[Illustration: FIG. 93--Killifish (_Fundulus heteroliatus_). (From
+Bull. 47, U.S. Fish Com.)]
+
+[Illustration: FIG. 94--Stickleback (_Apeltes quadracus_). (From Bull.
+47, U.S. Fish Com.)]
+
+[Illustration: FIG. 95--An old watering trough, an excellent
+breeding-place for mosquitoes.]
+
+
+FIGHTING THE LARVAE
+
+All of the efforts directed against the adult mosquitoes are usually of
+little avail in decreasing the number in any region. It is comparatively
+easy, however, to fight them successfully in the larval stage. We have
+seen that standing water is absolutely necessary for mosquitoes to breed
+in. This makes the problem much simpler than if they could breed in any
+moist places such as well-sprinkled lawns, a shady part of the garden,
+etc. The whole problem of successful campaigns against the mosquitoes
+resolves itself into the problem of finding and destroying or properly
+treating their breeding-places. We have seen how certain kinds, such as
+the yellow fever mosquito, are "domestic" species. They never go far
+from their breeding-places. If a house is infected by one of these
+species the immediate premises should be searched for the source.
+Cisterns, rain-barrels, sewer-traps, cesspools, tubs or buckets of water
+or old tin cans in out-of-the-way corners, are all suitable places for
+them to breed in. Cisterns and rain-barrels should be thoroughly
+screened so that no mosquitoes can get in or out, or the surface should
+be covered with a film of kerosene which will kill all the larvae in the
+water when they come to the surface to breathe, and will also kill the
+females when they come to deposit their eggs. The vent to open cesspools
+should be thoroughly screened or the surface of the water kept well
+covered with oil. Water standing in any vessels in the yards should be
+emptied every week or ten days and the old tin cans destroyed or hauled
+away. In fighting these domestic species you need be concerned only with
+your own yard and that of your near-by neighbors. Other species, while
+also rather local in their distribution, fly much farther than the
+really domestic ones. In fighting these the region for a considerable
+distance around must be taken into consideration. Watering-troughs (Fig.
+95) that are left filled from week to week, the overflow from such
+places, and the tracks made in the mud round about them (Fig. 96), small
+sluggish streams, irrigating ditches, and small ponds or lakes not
+supplied with fish are excellent breeding-places for several species of
+mosquitoes including _Anopheles_ and others. The remedy at once suggests
+itself. The watering-trough can be emptied and renewed every week during
+the summer time, the overflow can be taken care of in a ditch that will
+lead it away from the trough to where it will sink into the ground, the
+banks of the streams or ponds or lakes can be cleared in such a way that
+fish can get to all parts of the water; most of the small ponds can be
+drained or their surface may be covered over with a thin film of
+kerosene. This is best applied as a spray; one ounce to fifteen square
+feet will suffice. If the oil is simply poured over the surface more
+will be required.
+
+The fighting of the species that breed on the extensive salt-marshes in
+many regions is a larger and more difficult problem, but as it is a
+matter that usually concerns large communities, sometimes whole states,
+it can be dealt with on a larger scale. The very excellent results that
+have been accomplished in New Jersey and on the San Francisco peninsula,
+and in a smaller way in other places, show what may be done if the
+community goes about the fight in an intelligent manner. In the fight in
+New Jersey hundreds of acres of tide-lands have been drained so that
+they no longer have tide pools standing where the mosquitoes may breed.
+When it is impracticable to drain them the pools may be sprayed
+occasionally with kerosene.
+
+The value of the land that is reclaimed by a good system of draining is
+often enough to pay many times over the cost of draining, thus the
+mosquitoes are gotten rid of and the land enhanced in value by a single
+operation.
+
+
+
+
+CHAPTER VII
+
+MOSQUITOES AND MALARIA
+
+
+Ever since the beginning of history we have records of certain fevers
+that have been called by different names according to the people that
+were affected. As we study these names and the various writings
+concerning the fevers we find that a great group of the most important
+of them are what we to-day know as malarial fevers. Not only are these
+ills as old as history but they have been observed over almost the
+entire inhabited earth. There are certain regions in all countries where
+malaria does not occur, but almost always it will be found that other
+regions near by are infected and it very often happens that these
+infected regions are the most profitable parts of the land, the places
+where water is plentiful and vegetation is luxuriant. Indeed the
+coincidence of these two things, low-lying lands with an abundance of
+water, particularly standing water, and malaria has always been noted
+and gave rise to the earliest theories in regard to the cause of the
+disease.
+
+For instance, we find some of the very early writers emphasizing the
+point that swampy localities should be avoided for they produce animals
+that give rise to disease, or that the air is poisoned by the breath of
+the swamp-inhabiting animals.
+
+These views of the origin of the fever prevailed until about the
+beginning of the eighteenth century when the recently discovered
+microscope began to reveal the various kinds of animalculae to be found
+in decaying material.
+
+In 1718 Lancisi held that the myriads of insects, particularly gnats or
+mosquitoes, that arose from such swampy regions might carry some of
+these poisonous substances and by means of their proboscis introduce
+them into the bodies of the people, and although he had made no
+experiments to test the assumption he did not consider it impossible
+that such insects might also introduce the smallest animalculae into the
+blood. It took almost two centuries of study and investigation before
+this guess was proved to be right.
+
+One reason why the mosquitoes were not earlier associated with these
+diseases was that all who investigated the matter at all turned their
+attention to the bad condition of the air in these swampy regions.
+Malaria means bad air. We all know that we can see the mists arising
+from such regions, particularly in the evening or at night, and as
+exposure to these mists very often meant an attack of malaria they were
+naturally supposed to be the cause of the disease. So for a long time
+the whole attention of investigators was turned toward studying and
+analyzing these vapors, and various experiments were made which seemed
+to show conclusively that the malaria was caused only by these
+emanations. The investigations even went so far that the exact germs
+that were supposed to cause the fever were separated and experimented
+with.
+
+
+THE PARASITE THAT CAUSES MALARIA
+
+The blood had been studied time and again and the characteristic
+appearance of the blood of a malarial patient was well known. In 1880
+Laveran, a French army surgeon in Algiers, began to study the blood of
+such patients microscopically and soon was able to demonstrate the
+parasite that caused the disease. His discoveries were not readily
+accepted, but other investigations soon confirmed his observations and
+the fact was gradually firmly established. Not until recently, however,
+did this distinguished physician receive a full recognition of his work.
+A few years ago he was awarded the Nobel prize for medicine, perhaps the
+highest honor that can be bestowed on any physician. It is interesting,
+too, to note in this connection that it was another French surgeon who
+in 1840 discovered that sulphate of quinine is a specific for malaria.
+
+[Illustration: FIG. 96--Horse and cattle tracks in mud filled with
+water; good breeding-places for Anopheles.]
+
+[Illustration: FIG. 97--A malarial mosquito (_Anopheles maculipennis_);
+male.]
+
+[Illustration: FIG. 98--A malarial mosquito (_A. maculipennis_);
+female.]
+
+The next important step was made in 1885 by Golgi, an Italian, who
+studied the life-history of the parasite in the blood and distinguished
+the three forms which cause the three most familiar kinds of malarial
+fevers, the tertian, the quartan and the remittent types. From this time
+on this parasite has been studied by physicians of many nationalities
+and the whole course of its life-history worked out. In order that we
+may understand how it was that mosquitoes were determined to be the
+means of disseminating this parasite we will discuss first its
+life-history in the human blood.
+
+The parasites that cause the malarial fevers are Sporozoans and belong
+to the genus _Plasmodium_. Other names such as _Haemamoeba_ and
+_Laverania_ have been used for them, but the term _Plasmodium_ is the
+one now most commonly employed. The three most common species are
+_vivax_, _malariae_ and _falciparum_, causing respectively the tertian,
+quartan and remittent fevers.
+
+
+LIFE-HISTORY OF PARASITE
+
+The life-history of all of these is very similar, the principal
+difference being in the length of time it takes them to sporulate. Let
+us begin with the parasite after it has been introduced into the blood
+and trace its development there. At first it is slender and rod-like in
+shape. It has some power of movement in the blood-plasm. Very soon it
+attacks one of the red blood-corpuscles and gradually pierces its way
+through the wall and into the corpuscle substance (Fig. 99); here it
+becomes more amoeboid and continues to move about, feeding all the
+time on the corpuscle substance, gradually destroying the whole cell. As
+the parasite feeds and grows there is deposited within its body a
+blackish or brownish pigment known as melanin.
+
+During the time that the parasite is feeding and growing it is also
+giving off waste products, as all living forms do in the process of
+metabolism, but as the parasite is completely inclosed in the corpuscle
+wall these waste products cannot escape until the wall bursts open.
+After about forty hours if the parasite is _vivax_ or about sixty-five
+hours if it is _malariae_ it becomes immobile, the nucleus divides again
+and again and the protoplasm collects around these nuclei, forming a
+number of small cells or spores, as they are called. In about
+forty-eight or seventy-two hours, depending on whether the parasite is
+_vivax_ or _malariae_ the wall of the corpuscle bursts and all these
+spores with the black pigment and the waste products that have been
+stored away within the cell are liberated into the blood-plasm.
+
+[Illustration: FIG. 99--Diagram to illustrate the life-history of the
+malarial parasite. 1 is a red blood-corpuscle, 2 to 7 shows the
+development of the parasite in the corpuscle, _a_ _b_ _c_ _d_ and _a'_
+_b'_ _c'_ and _e_ the development of the parasite in the stomach of the
+mosquito, _f_ _g_ _h_ _i_ the development in the capsule on the outer
+wall of the stomach of the mosquito, _k_ in the salivary gland.]
+
+[Illustration: FIG. 100--Malarial mosquito (_A. maculipennis_) on the
+wall.]
+
+[Illustration: FIG. 101--Malarial mosquito (_A. maculipennis_) standing
+on a table.]
+
+These spores are round or somewhat amoeboid and are carried in the
+blood for a short time. Very soon, however, each one attacks a new red
+corpuscle and the process of feeding, growth and spore-formation
+continues, taking exactly the same time for development as in the first
+generation, so every forty-eight hours in the case of the _vivax_, and
+every seventy-two hours in the case of the _malariae_ a new lot of these
+spores and the accompanying waste products are thrown out into the
+blood. Thus in a very short time many generations of this parasite occur
+and thousands or hundreds of thousands of the red-blood corpuscles are
+destroyed, leaving the patient weak and anemic. It will be seen, too,
+that the recurrence of the chills and fevers is simultaneous with the
+escaping of the parasites from the blood-corpuscles, together with the
+waste products of their metabolism.
+
+These waste products are poisonous, and it is believed that this great
+amount of poison poured into the blood at one time causes the regular
+recurring crisis. Zooelogists well know that this process of asexual
+reproduction, _i. e._, reproduction without any conjugation of two
+different cells, cannot go on indefinitely, and those who were studying
+the life-cycle of these parasites were at a loss to know where the
+sexual stage took place. In the meantime studies of other parasites more
+or less closely related to _Plasmodium_ showed that the sexual stage
+occurred outside the vertebrate host. The remarkable work of Dr. Smith
+on the life-history of the germ that causes the Texas fever of cattle
+had a strong influence in directing the search for this other stage of
+the malarial parasite. Another thing that indicated that this sexual
+generation must take place outside the body of the vertebrate host was
+the fact that the investigators found that the parasites in certain of
+the cells did not sporulate as did the others. When these individuals
+were drawn from the circulation and placed on a slide for study it was
+found that they would swell up and free themselves from the inclosing
+corpuscle and some of them would emit long filaments which would dart
+away among the corpuscles.
+
+Many men have worked on this problem, but perhaps the most credit for
+its solution will always be given to Sir Patrick Manson, the foremost
+authority on tropical diseases, and to Ronald Ross, a surgeon in the
+English army. There is no more interesting and inspiring reading than
+that which deals with the development of the hypothesis by Manson and
+the persistent faith of Ross in the correctness of this theory, and his
+continuous indefatigable labors in trying to demonstrate it. It was an
+important piece of scientific work, and shows what a man can do even
+when the obstacles seem insurmountable.
+
+
+THE PARASITE IN THE MOSQUITO
+
+Briefly stated again, the problem was this: We have here a parasite in
+the blood which behaves as do many other forms of life. Some of these
+parasites do not go on with their development until they are removed
+from the circulation. Now, how are they thus removed from the
+circulation under normal conditions? This must first be solved before
+the still greater and more important problem of how the parasite gets
+from one human host to another can be taken up. In studying this over
+Manson reasoned that certain suctorial insects were the agencies through
+which blood was most commonly removed from the circulation and he
+ventured the guess that this change in the parasite that may be seen
+taking place on the slide under the microscope, normally takes place in
+the stomach of some insect that sucks man's blood. Ross was greatly
+impressed with the theory and began his long and apparently hopeless
+task of finding these parasites in the stomach of some insect. When we
+remember that they are so minute that they can only be seen by the use
+of the highest power of the microscope we can realize something of the
+magnitude of the task. Ross, who was at that time stationed in India,
+selected the mosquito as the most likely of the insects to be the host
+that he was looking for. For over two and one-half years he worked with
+entirely negative results, for after examining thoroughly many thousands
+of mosquitoes he found no trace of the parasite.
+
+Practically all his work was done on the most common mosquito of the
+region, a species of _Culex_. But one day a friend sent him a different
+mosquito, one with spotted wings, and in examining it he was interested
+to note certain oval or round nodules on the outer walls of the stomach.
+On closer examinations he found that each of these nodules contained a
+few granules of the coal-black melanin of malarial fever. Further
+studies and experiments showed that these particular cells could always
+be found in the walls of the stomach of this particular species of
+mosquito a few days after it had bitten a malarial patient. This
+epoch-making discovery was made in 1898. Ross was detailed by the
+English government to devote his whole time to the further solution of
+the problem, and after two years more of careful experimentation and
+study was able to give a complete life-history of this parasite. His
+experiments have been repeated many times, and the conclusions he
+arrived at are as undeniable as any of the known facts of science.
+
+The whole life-history as we now know it can be summed up as follows:
+The parasites develop within the circulation but certain of them seem to
+wander about and do not go on with their development there. When these
+particular parasites are taken into the stomach of most mosquitoes they
+are digested with the rest of the blood. But when they are taken into
+the stomach of a mosquito belonging to the genus _Anopheles_ or other
+closely related genera they are not digested but go on with their
+development, conjugation and fertilization taking place, resulting in a
+more elongated form which makes its way through the walls of the stomach
+on the outside of which are formed the little nodules discovered by Ross
+on his mosquitoes. Within these nodules further division and development
+takes place until finally the nodule is burst open and many thousand
+minute rod-like organisms, sporozoites, are turned loose into the
+body-cavity of the mosquito. Owing to some unknown cause these little
+organisms are gathered together in the large vacuolated cells of the
+salivary glands of the mosquito, and when the mosquito bites a man or
+any other animal they pour down through the ducts with the secretion and
+are thus again introduced in the circulation.
+
+The nodules or cysts on the walls of the stomach of the mosquito may
+contain as many as ten thousand sporozoites, and as many as five hundred
+cysts may occur on a single stomach.
+
+It takes ten, twelve or more days from the time the parasites are taken
+into the stomach of the mosquito before they can go through their
+transformations and reach the salivary gland, the time depending on the
+temperature. So it is ten or twelve days or sometimes as much as
+eighteen or twenty days from the time an _Anopheles_ bites a malarial
+patient before it is dangerous or can spread the disease. On the other
+hand, the sporozoites may lie in the salivary gland alive and virulent
+for several weeks. It does not give up all the parasites at one time, so
+that three or four or more people may be affected by a single mosquito.
+
+It is well known that two parasites may often be seen in the same
+corpuscle. This is often simply a case of multiple infection, but Dr.
+Craig has very recently shown that under certain conditions two
+individuals may enter the same corpuscle and conjugate and the resulting
+individual will be resistant to quinine and may remain latent in the
+spleen or bone marrow for a long time. Under favorable conditions it
+may again begin the process of multiplication and the patient will
+suffer a relapse.
+
+
+SUMMARY
+
+Now let us sum up some of the reasons why we believe that the malaria
+fever can be transmitted only through the agency of mosquitoes. First,
+we know the life-history of the parasite, it has been studied in both of
+its hosts. Attempts have been made to rear it in other hosts but without
+avail, and we know from the general relations of the parasite that it
+must have this sexual as well as the asexual generations. Second, in
+some regions which would seem to be malarial, that is, where the
+miasmatic mists arise, no malaria occurs. Why? Usually it can be
+definitely shown that no _Anopheles_ occur there. Other mosquitoes may
+be there in abundance, but if no _Anopheles_, there is no malaria. In
+certain regions this is well demonstrated. The west coast of Africa is
+one of the worst pest-holes of malaria and _Anopheles_. The east coast
+has no malaria and no _Anopheles_. In many islands the same condition
+exists. On the other hand, the Fiji Islands have _Anopheles_ but no
+malaria. No malaria has ever been introduced there to infect the
+mosquitoes. In the same way _Stegomyia_ occurs in some of the South Sea
+islands and yet there is no yellow fever there.
+
+
+EXPERIMENTS
+
+We may review, too, a few of the classic experiments that have served to
+show that malaria can be contracted in no other way than through the
+bite of the mosquito.
+
+For many years Grassi, an Italian, devoted almost his whole time to the
+study of malaria. In 1900 he received permission from the government to
+experiment on the employees of a piece of railroad that was being built
+through a malarial region. This was divided for the purpose of the
+experiment into three sections, a protected zone in the middle and an
+unprotected zone at each end.
+
+Those working in the protected zone had their houses completely screened
+and no one was allowed out of doors after sunset except they were
+protected with veils and gloves. Early in the season they were all given
+doses of quinine to prevent auto-infection. In the unprotected zone no
+screens were used and every one was allowed to go without special
+protection. The result for the summer was that there were no new cases
+of fever in the protected zone. In the unprotected zones practically all
+had the fever as usual.
+
+[Illustration: FIG. 102--Salt-marsh mosquito (_O. lativittatus_)
+standing on a table.]
+
+[Illustration: FIG. 103--Anopheles hanging from the ceiling.]
+
+In the same year two English physicians, Sambon and Low, went to Italy
+where they built a cabin in one of the marshes noted as being a malaria
+pest-hole. The house was thoroughly screened so that no mosquitoes could
+enter, but the windows were always open so as to admit the air freely
+day and night. Here they lived for three months, out of doors as much as
+they pleased during the day but inside where they were protected from
+the mosquitoes at night. No quinine was used and no fever developed,
+although all about them other people were having the fever as usual.
+
+Another English physician who had not been in malarial regions allowed
+himself to be bitten by infected mosquitoes sent from a malarial
+locality. In due time he developed the fever. Many other experiments
+made in various places might be cited. The results have all been
+practically the same. To-day the soldiers of many civilized nations are
+required to protect themselves from mosquitoes because it has been found
+that it pays. Disease has always been a worse terror than bullets in any
+war, and we are fast learning that the great loss from diseases
+heretofore considered unavoidable may be very largely eliminated by
+proper sanitary arrangements and protection from noxious insects.
+
+
+
+
+CHAPTER VIII
+
+MOSQUITOES AND YELLOW FEVER
+
+
+Yellow fever is a disease, principally of seaport towns, from which the
+United States has suffered more than any other country. It is endemic
+only in tropical regions but is often carried to subtropical, sometimes
+even to temperate zones where, if the proper mosquitoes exist, it may
+rage until frost.
+
+Vera Cruz, Havana, Rio de Janeiro, and the west coast of Africa were
+long regarded as permanent endemic foci, the disease appearing there in
+epidemic form from time to time, often spreading to other ports in more
+or less close communication with such places. In the United States the
+Gulf states have been the greatest sufferers from the disease, although
+it has spread as far as Baltimore, Philadelphia and Washington, where at
+rare intervals it was most serious, abating its ravages only when frost
+came.
+
+The last severe outbreak occurred in New Orleans in 1905 when eight
+thousand cases and nine hundred deaths occurred. At that time there was
+waged one of the most remarkable warfares against death in its most
+terrifying form that the world has ever known. And, thanks to the
+achievements of science, particularly to the investigations of three
+men, one of whom gave his life to the cause, the fight was successful
+and this dreadful outbreak was checked just at the time when according
+to all precedent it should have been at its height.
+
+This result which at other times and under other conditions would have
+been considered miraculous was achieved not by the usual custom of
+isolation, quarantine, etc., but by a direct, we may almost say hand to
+hand, conflict with mosquitoes: the mosquitoes belonging to a particular
+genus and species, _Stegomyia calopus_ (_fasciata_).
+
+Before taking up a discussion of this achievement in New Orleans let us
+consider first the work of the men that made such results possible.
+
+For many years the cause and methods of dissemination of this disease
+had been a puzzle to physicians and scientists. Very early it was
+believed that it might be transmitted through the air, and the fact that
+infection usually occurred in the vicinity of the water and in the
+tropics or in midsummer led to the belief that the disease was due to
+fermentation. This theory received strong support in the fact that
+serious outbreaks of the fever often followed the coming into port of
+vessels from the tropics with the water in their holds in an offensive
+condition. When it was discovered that bacteria were the cause of
+fermentation and also of many diseases this theory was considered
+abundantly proven. From time to time, announcements have been made that
+the particular species of bacteria that causes the disease has been
+isolated, but there has always been something lacking in the final
+proof.
+
+Yellow fever has always been regarded as a very highly contagious as
+well as infectious disease, and the utmost precaution has been taken to
+isolate the patients when possible and in recent years strict
+quarantines have been established against infected localities and no
+person or commerce or even the mails were allowed to come from such
+places without thorough fumigations. But all these things proved
+unsatisfactory. The disease could not ordinarily be checked by simply
+isolating the patients. Many people became sick without ever having been
+near a yellow fever patient, while others worked in direct daily contact
+with the disease and did not suffer from it. Those who had once had it
+and recovered became practically immune, rarely suffering from a second
+attack. Negroes may suffer from the disease, but are usually regarded as
+practically immune.
+
+[Illustration: FIG. 104--Yellow-fever mosquito (_Stegomyia calopus_).
+(R. Newstead, del.)]
+
+It was early observed, too, that the danger zone might be quite well
+defined and that outside this zone one would be safe. More than a
+century ago the British troops and other inhabitants of Jamaica found
+that by retreating to the mountains during the warm weather the
+non-immunes could escape the fever. It was also observed that those who
+slept on the first floor were more apt to take the disease than those on
+the second floor.
+
+
+THE YELLOW FEVER COMMISSION
+
+In 1900, during the American occupation of Cuba, yellow fever became
+very prevalent there. A board of medical officers was ordered to meet in
+Havana for the purpose of studying the disease under the favorable
+opportunities thus afforded. This board, which came to be known as the
+Yellow Fever Commission, was composed of Drs. Walter Reed, James
+Carroll, Jessie W. Lazear and Aristides Agramonte of the United States
+Army. Agramonte was a Cuban and an immune, the others were non-immunes.
+Dr. Manson in his lectures on Tropical Medicines says of them:
+
+     "I cannot pass on, however, to what I have to say in connection
+     with this work without a word of admiration for the insight, the
+     energy, the skill, the courage, and withal the modesty and
+     simplicity of the leader of that remarkable band of workers. If any
+     man deserved a monument to his memory, it was Reed. If any band of
+     men deserve recognition at the hands of their countrymen, it is
+     Reed's colleagues."
+
+Their first work was to determine whether any of the germs that had been
+claimed to be the cause of yellow fever were really responsible for the
+disease. _Bacillus icteroides_ that for some time and by some
+investigators had been named as the offender was particularly
+investigated, but was proved to be a secondary invader only.
+
+Dr. Charles Finlay of Havana had been claiming for some years that the
+yellow fever was transmitted by means of the mosquito and possibly by
+other insects also. He even claimed to have proved this theory
+experimentally. We know now, however, that there must have been errors
+in his experiments and that his patients became infected from sources
+other than those he was dealing with.
+
+The Yellow Fever Commission decided to put this theory to the test and
+secured a number of volunteers for the experiments. The first thing was
+to let an infected mosquito bite some non-immune person. How this was
+done and the results, may be told in Dr. Carroll's own words.
+
+
+EXPERIMENTS
+
+     "Two separate lines of work now presented: one, the study of the
+     bacterial flora of the intestine and anaerobic cultures from the
+     blood and various organs; the other, the theory of the transmission
+     of the disease by the mosquito, which had been advanced by Dr.
+     Carlos Finlay in 1881. After due consideration it was decided to
+     investigate the latter first. Then arose the question of the
+     tremendous responsibility involved in the use of human beings for
+     experimental purposes. It was concluded that the results
+     themselves, if positive, would be sufficient justification of the
+     undertaking. It was suggested that we subject ourselves to the same
+     risk and this suggestion was accepted by Dr. Reed and Dr. Lazear.
+     It became necessary for Dr. Reed to return to the United States and
+     the work was begun by Dr. Lazear, who applied infected mosquitoes
+     to a number of persons, himself included, without result. On the
+     afternoon of July 27, 1900, I submitted myself to the bite of an
+     infected mosquito applied by Dr. Lazear. The insect had been reared
+     and hatched in the laboratory, had been caused to feed upon four
+     cases of yellow fever, two of them severe, and two mild. The first
+     patient, a severe case, was bitten twelve days before; the second,
+     third and fourth patients had been bitten six, four and two days
+     previously, and were in character mild, severe and mild
+     respectively. In writing to Dr. Reed that night of the incident, I
+     remarked jokingly that if there was anything in the mosquito
+     theory, I should have a good dose. And so it happened. After having
+     slight premonitory symptoms for two days, I was taken sick on
+     August 31, and on September 1, I was carried to the yellow fever
+     camp. My life was in the balance for three days, and my chart shows
+     that on the fifth, sixth and seventh days my urine contained
+     eighth-tenths and nine-tenths of moist albumin. On the day I was
+     taken sick, August 31, 1900, Dr. Lazear applied the same mosquito,
+     with three others, to another individual who suffered a
+     comparatively mild attack and was well before I had left my bed. It
+     so happened that I was the first person in whom the mosquito was
+     proved to convey the disease.
+
+     "On the eighteenth of September, five days after I was permitted to
+     leave my bed, Dr. Lazear was stricken, and died in convulsions just
+     one week later, after several days of delirium with black vomit.
+     Such is yellow fever.
+
+     "He was bitten by a stray mosquito while applying the other insects
+     to a patient in one of the city hospitals. He did not recognize it
+     as a _Stegomyia_, and thought it was a _Culex_. It was permitted to
+     take its fill and he attached no importance to the bite until after
+     he was taken sick, when he related the incident to me. I shall
+     never forget the expression of alarm in his eyes when I last saw
+     him alive in the third or fourth day of his illness. The spasmodic
+     contractions of his diaphragm indicated that black vomit was
+     impending, and he fully appreciated their significance. The
+     dreaded vomit soon appeared. I was too weak to see him again in
+     that condition, and there was nothing that I could do to help him.
+
+     "Dr. Lazear left a wife and two young children, one of whom he had
+     never seen."
+
+These experiments and many others like them conducted on soldiers and
+Spanish immigrants proved that this particular mosquito would transmit
+the disease under certain conditions.
+
+1. The mosquito must bite the patient during the first three days of the
+fever; after that a yellow fever patient cannot infect a mosquito.
+
+2. A period of twelve days must elapse before the mosquito is able to
+infect another person. After that she may infect anyone she may bite;
+that is, the germs remain virulent during the rest of the mosquito's
+life. The French Yellow Fever Commission working in Rio de Janeiro claim
+that the first generation of offspring from such an infected mosquito is
+capable of causing the disease after they are fourteen days in the adult
+condition.
+
+The next step was to ascertain whether the disease could be contracted
+in any other way than by the bites of infected mosquitoes. A camp named
+Camp Lazear was established and the following tests made: A
+mosquito-proof building of one room was completely divided by a wire
+screen from floor to ceiling. In one room fifteen mosquitoes that had
+previously bitten yellow fever patients and had undergone the proper
+period of incubation were liberated. In this room a non-immune exposed
+himself so that he was bitten by several of the insects. A little later
+the same day and again the next day the mosquitoes were allowed to feed
+on him for a few minutes. Five days later, the usual incubation period,
+he developed yellow fever.
+
+At the same time that he entered the building two other non-immunes
+entered the other compartment where they slept for eighteen nights
+separated from the mosquitoes by the wire screen. They showed no signs
+of taking the fever.
+
+In another mosquito-proof house two soldiers and a surgeon, all
+non-immunes, lived for twenty-one days. From time to time they were
+supplied with soiled articles of bedding, clothing, etc., direct from
+the yellow fever hospital in the city. These articles had been soiled by
+the urine, fecal matter and black vomit obtained from fatal and other
+cases of yellow fever. These articles were handled and shaken daily, but
+no disease developed among the men and at the end of the twenty-one
+days, two other non-immunes relieved them and handled a new supply of
+clothing in the same way, sleeping between the same sheets that had
+been used by a patient dying of yellow fever and exposing themselves in
+every possible way to the soiled clothing. But no disease developed.
+That these men were susceptible was shown later by inoculating some of
+them, when they developed the disease.
+
+In another experiment certain men in a camp allowed themselves to be
+bitten by mosquitoes that had passed through the proper period of
+incubation and every one of them and no others contracted the disease.
+It was also shown that a mosquito was capable of communicating the
+disease as long as fifty-seven days after it had bitten a yellow fever
+patient. Another set of experiments showed that a subcutaneous injection
+into a non-immune of a very small quantity of blood from the veins of a
+yellow fever patient in the first two or three days of the disease would
+produce the fever.
+
+
+SUMMARY OF RESULTS
+
+Since that time much other work has been done by independent workers as
+well as by French and English Commissions both working at Rio de
+Janeiro. The results of their investigation are practically the same and
+may be summed up as follows:
+
+1. The virus of the yellow fever is in the blood-plasma, not in the
+corpuscles, for these may be removed and the plasma still be infective.
+
+2. The virus is conveyed from one patient to another by the yellow fever
+mosquito, _Stegomyia calopus_, and in no other way except by
+experimental injections.
+
+3. The patient is a source of infection only during the first three or
+four days of the disease (this after the three to six days of
+incubation).
+
+4. The virus must undergo an incubation period of twelve to fourteen
+days in the mosquito before she is capable of transmitting the disease.
+
+5. The parasite, whatever it is, has never been seen. It is probably too
+small to be seen by any of our present microscopes, even the recently
+invented ultramicroscope. It is probably not a bacterial parasite but
+very likely a Protozoan, and certain specialists have even shown by the
+study of all the available data that it almost certainly belongs to the
+Sporozoan genus _Spirocheta_.
+
+Now what does all this mean? It means the saving of hundreds of human
+lives annually. It means the banishing from many localities and possibly
+very soon from the face of the earth of a disease that since the
+earliest settlements on this continent has been a source of terror. It
+means the making habitable of certain places which heretofore a white
+man has entered only at the risk of his life. It means that quarantines
+need no longer be established when yellow fever breaks out in a
+district; quarantines which have inevitably caused the loss of millions
+of dollars to the world of commerce.
+
+
+RESULTS IN HAVANA
+
+The first practical work based on these findings was done in Havana. The
+Yellow Fever Commission made their recommendations in 1900. In 1901 and
+1902 they were put into effect. The following table of the death rate
+there during a period of ten years shows graphically the results:
+
+DEATHS IN HAVANA FROM YELLOW FEVER
+
+-----+------+------+------+------+------+------+------+------+------+------
+     | 1893 | 1894 | 1895 | 1896 | 1897 | 1898 | 1899 | 1900 | 1901 | 1902
+-----+------+------+------+------+------+------+------+------+------+------
+Jan. |  15  |   7  |  15  |  10  |  69  |   7  |   1  |   8  |   7  |   0
+Feb. |   6  |   4  |   4  |   7  |  24  |   1  |   0  |   9  |   5  |   0
+Mar. |   4  |   2  |   2  |   3  |  30  |   2  |   1  |   4  |   1  |   0
+Apr. |   8  |   4  |   6  |  14  |  71  |   1  |   2  |   0  |   0  |   0
+May  |  23  |  16  |  10  |  27  |  88  |   4  |   0  |   2  |   0  |   0
+June |  69  |  31  |  16  |  46  | 174  |   3  |   1  |   8  |   0  |   0
+July | 118  |  77  |  88  | 116  | 168  |  16  |   2  |  30  |   1  |   0
+Aug. | 100  |  73  | 120  | 262  | 102  |  16  |  13  |  49  |   2  |   0
+Sep. |  68  |  76  | 135  | 166  |  56  |  34  |  18  |  52  |   2  |   0
+Oct. |  46  |  40  | 102  | 240  |  42  |  26  |  25  |  74  |   0  |   0
+Nov. |  28  |  23  |  35  | 244  |  26  |  13  |  18  |  54  |   0  |   0
+Dec. |  11  |  29  |  20  | 147  |   8  |  13  |  22  |  20  |   0  |   0
+-----+------+------+------+------+------+------+------+------+------+------
+
+As long as the United States held control at Havana the yellow fever
+was kept in check by fighting the mosquitoes, when this vigilance was
+relaxed the fever began to appear again and the Cubans found that it was
+necessary to keep up the fight against the mosquitoes if the island was
+to be kept free from the disease.
+
+
+THE FIGHT IN NEW ORLEANS
+
+In the summer of 1905 came another opportunity to put the knowledge
+gained during these experiments to a practical test. Samuel Hopkins
+Adams in his article in _McClure's Magazine_, June, 1906, says of the
+beginning of this fight:
+
+     "Eight years before, the mosquito-plague had infected the great,
+     busy, joyous metropolis of the south. Ignorant of the real
+     processes of the infection, New Orleans had fought it blindly,
+     frantically, in an agony of panic, and when at last the frost put
+     an end to the helpless city's plight, she lay spent and prostrate.
+     The yellow fever of 1905 came with a more formidable and unexpected
+     suddenness than that of 1897. It sprang into life like a secret and
+     armed uprising in the midst of the city, full-fledged and terrible.
+     But there arose against it the trained fighting line of scientific
+     knowledge. Accepting, with a fine courage of faith that most
+     important preventive discovery since vaccination, the mosquito
+     dogma, the Crescent City marshaled her defenses. This time there
+     was no panic, no mob-rule of terrified thousands, no mad rushing
+     from stunned inertia to wildly impractical action; but instead the
+     enlistment of the whole city in an army of sanitation. Every
+     citizen became a soldier of the public health. And when, long
+     before the plague-killing frost came, the battle was over, New
+     Orleans had triumphed not only in the most brilliant hygienic
+     victory ever achieved in America, but in a principle for which the
+     whole nation owes her a debt of gratitude."
+
+For some time the authorities had been trying to keep secret the fact
+that the disease was prevalent, but the rapidity with which it spread
+made them realize that only united action on the part of all the
+community would be of any avail. The Citizens Volunteer Ward
+Organizations were organized for the purpose of fighting the mosquitoes
+which were everywhere. To many the fight looked hopeless. The miles of
+open gutters, the thousands of cisterns and little pools of standing
+water everywhere furnished abundant breeding-places for the mosquitoes.
+The ditches and ponds were drained or salted, the cisterns were
+screened, infected houses were fumigated, yet the fever continued to
+spread. Rains refilled the ditches, winds tore the screens from the
+cisterns, the ignorant people of the French quarter refused to
+cooeperate. At last the city in desperation appealed to the President for
+aid. Surgeon J.H. White and a number of officers and men of the United
+States Public Health and Marine Hospital Service soon took charge of the
+work. This was continued along the same lines as before with the same
+object in view. But with the coming of the regulars the work was more
+systematically and thoroughly done. Every case of fever was treated as
+though it was yellow fever and every precaution taken to prevent
+mosquitoes from biting such a patient. The houses in which the fever
+occurred were thoroughly fumigated to kill any mosquitoes that might be
+there, and the neighborhood was thoroughly searched to find any places
+where the mosquitoes might be breeding. So confident were the
+authorities that the mosquito was the sole cause of the disease
+spreading, that besides fighting it no other work was undertaken save to
+make the sick as comfortable as possible.
+
+Finally the results began to be apparent. The number of cases gradually
+diminished, until long before frost came the city was free from the
+great pest. Yellow fever will doubtless appear from time to time in New
+Orleans and other cities, but there is, at least there should be, small
+danger of another great epidemic, for the people now know how the
+disease is caused and the remedy.
+
+Not long since I had occasion to write to a prominent entomologist in
+Louisiana for some specimens of the yellow fever mosquito for laboratory
+work. The following extract from his reply will show something of the
+work that is still being done there.
+
+     "I am afraid we cannot furnish specimens of _Stegomyia_, in spite
+     of the fact that Louisiana is _supposed_ to be the most favorable
+     home of this species in the South. Since the light occurrence of
+     yellow fever in this State in 1905, a very vigorous war has been
+     kept up against _Stegomyia_, and the ordinances of all Louisiana
+     cities and principal towns require the draining of all breeding
+     places of this mosquito and the constant oiling or screening of all
+     cisterns or other water containers. The result is this species is
+     very rare. Here in Baton Rouge I only see one once in a great
+     while, and it would require perhaps a good many days' work at the
+     present season to get as good specimens and as many of them as you
+     require."
+
+
+IN THE PANAMA CANAL ZONE
+
+Yellow fever was one of the worst obstacles that confronted the French
+when they were attempting to build the Panama Canal. The story of the
+suffering and death from this dread disease there is most pathetic.
+Ship-load after ship-load of laborers were sent over, as those who had
+gone earlier succumbed to the fever. The contractors were responsible
+for their men while they were sick and in order to avoid having to pay
+hospital expenses the men were often discharged as soon as they showed
+signs of sickness. Many of them died along the roadside while
+endeavoring to reach some place where they could obtain aid. The
+hospitals were usually filled with yellow fever patients, a very large
+percentage of whom died.
+
+Not only the day laborers suffered but many of the engineers, doctors,
+nurses and others sickened and died of the disease. It is reported that
+eighteen young French engineers came over on one vessel and in a month
+after their arrival all but one had died of the yellow fever. Out of
+thirty-six nurses brought over at one time, twenty-four died of the
+fever, and during one month nine members of the medical staff of one of
+the hospitals succumbed.
+
+One of the first things that the United States Government did in
+beginning work in the canal zone was to take up the fight against the
+yellow fever mosquito. In Panama where the water for domestic purposes
+was kept in cisterns and water-barrels, inspectors were appointed to see
+that all such receptacles and other possible breeding-places for
+mosquitoes were kept covered. After the first inspection, 4,000
+breeding-places were reported. About six months later there were less
+than 400. Similar work was done in all the towns and settlements along
+the route of the canal. In addition to this fight against the yellow
+fever mosquito considerable attention was paid to the breeding-places of
+the malarial mosquito. The results have been remarkable. Cases of yellow
+fever are now rare throughout this zone, and there has been a very great
+reduction in the extent of the malarial districts. The last case of
+yellow fever occurred in May, 1906. Before this work was done a man took
+his life in his hands when he went into this region. Now it is regarded
+as a perfectly safe place to live. Indeed it is a much safer place than
+many sections of our own country where proper sanitary measures have not
+been taken to protect the health of the community.
+
+
+IN RIO DE JANEIRO
+
+In Rio de Janeiro they have as yet been unable to get rid of the
+mosquitoes, although thousands of dollars are spent annually in fighting
+them. But the non-immunes there protect themselves by doing their
+business in Rio during the day and going back at night to Petropolis,
+twenty-five miles inland and twenty-five hundred feet higher, where
+they are safe, for no _Stegomyia_ have ever been found there.
+
+They claim there that the yellow fever mosquito does not bite during the
+daytime after she has laid her eggs, and that she will not lay her eggs
+until about three days after she has fed on blood, therefore a
+_Stegomyia_ that bites during the day will not carry the yellow fever
+because she is too young. This seems to explain why the fever cannot be
+contracted by being bitten by a mosquito in the daytime. Certain other
+experiments, however, have given different results so that as far as we
+know it is not safe to be bitten at any time by such a mosquito in a
+region where the disease is endemic or where it is epidemic.
+
+In the main the work of the French Yellow Fever Commission working in
+Rio de Janeiro has confirmed the findings of the American Commission.
+One interesting special thing that the French Commission seems to have
+established is that the female may transmit the infecting power to her
+offspring, so that it would be possible for a mosquito that had never
+bitten a yellow fever patient to be capable of infecting a non-immune
+person. While all this is very probable in the light of what we know of
+the disease and the way in which other diseases caused by similar
+organisms may be transmitted by the parent to the offspring, yet the
+most conservative investigators are waiting for further proof.
+
+
+HABITS OF STEGOMYIA
+
+The whole fight against yellow fever, then is directed, as we have seen,
+against the mosquito, _Stegomyia calopus_. The habits of this species
+are such as to make it easy in some respects to combat. It is seldom
+found far away from human habitation. The adults will not fly far. Once
+in a house they usually stay there except when they leave to deposit
+their eggs.
+
+On the other hand, some of these same habits make it all the more
+dangerous. It will breed in almost any kind of water, no matter how
+filthy, and a very small amount will suffice. Thus any leaks from
+water-pipes or drains, cisterns, small cans of water or any such places
+may become dangerous breeding-places. If conditions are unfavorable
+there will often be developed small individuals which can easily make
+their way through ordinary mosquito-netting.
+
+Dr. Manson has pointed out an interesting possible result of the crusade
+that is now being waged against the yellow fever mosquitoes. The
+immunity of the people native to the endemic regions is supposed to be
+due to their having had mild attacks of the fever during childhood, for
+the children in these regions are subject to certain fevers which are
+probably very mild forms of yellow fever.
+
+Now if we kill practically all of the _Stegomyia_ so that these children
+do not have this fever there will be developed, in due time, a
+population most of whom are non-immune.
+
+This freedom from the disease for some time will allow us to grow
+careless in regard to fighting the mosquitoes. They will be allowed to
+increase and by some chance the yellow fever will again be introduced
+and there will then be very grave danger of most extensive and
+destructive epidemics.
+
+
+DANGER OF THE DISEASE IN THE PACIFIC ISLANDS
+
+I have already referred once or twice to the conditions in many of the
+Pacific tropical islands. In some of these various species of
+_Stegomyia_ are abundant, and in some _Stegomyia calopus_ is the most
+abundant and troublesome form. All the natives of these islands are
+non-immune because there has never been any yellow fever there. Unless
+extraordinary care is taken the disease will be introduced there sooner
+or later and the results are sure to be most appalling. The climatic and
+sanitary conditions and the habits of the people are ideal for the
+development and spread of the disease, and what I have seen of the
+conditions on some of these islands convinces me that it would be almost
+impossible to control the disease before it had a chance to kill a large
+percentage of the population.
+
+With the opening of the Panama Canal these things become more possible.
+Heretofore, the shipping to these regions has not been from ports where
+yellow fever was endemic or even likely to be epidemic. But unless the
+yellow fever is kept out of the canal zone, the danger will be many fold
+what it is now.
+
+The white man has already carried enough misery to these island peoples
+in the way of loathsome diseases, and it is to be hoped that this,
+another great curse, will not be carried to them with our civilization,
+the beneficial results of which have been so often very justly
+questioned.
+
+What I have said in regard to these islands applies with equal force and
+in some instances with even greater force to parts of Asia, the Eastern
+Archipelago and other places.
+
+
+
+
+CHAPTER IX
+
+FLEAS AND PLAGUE
+
+
+Plague has always been one of the most dreaded diseases, and when we
+read of its ravages in the old world and the utter helplessness of the
+people before it we do not wonder that the very word filled them with
+horror. One of the greatest scourges ever known began in Egypt about
+A.D. 542, and spread along the shores of the Mediterranean to Europe and
+Asia. It lasted for sixty years, appearing again and again in the same
+place and decimating whole communities.
+
+Another great pandemic, beginning in 1364, spread over the whole of the
+then known world and appeared in its most virulent form. On account of
+diffuse subcutaneous hemorrhages it came to be known as the "black
+death" and of course spread terror in all the communities where it
+appeared. Whole villages and districts were depopulated. The death-rate
+was very high, one authority placing the total mortality at twenty-five
+million.
+
+During this time new centers of infection were established, and since
+then it has been carried by the commerce of the nations to all parts of
+the world. It is not restricted, as many other epidemic diseases, to the
+tropics or semi-tropics, although as a matter of fact we find it is more
+prevalent in these regions on account of the sanitary conditions.
+
+
+HOW PLAGUE WAS CONTROLLED IN SAN FRANCISCO
+
+Attention is called to these things in order that we may compare past
+conditions with present. During the last few years San Francisco has
+been fighting an outbreak of plague that in other days would have been
+nothing less than a national calamity. But with modern methods of
+handling it, based on knowing what it is, what causes it and how it is
+spread, the authorities there have been able not only to hold the
+disease in check, but practically to stamp it out with the loss of
+comparatively few lives.
+
+Dr. Blue of the Public Health and Marine Hospital Service and his
+co-workers directed their whole energy toward controlling the rats. A
+small army of men were employed, catching rats in every quarter of the
+city. Dr. Rucker reports that fully a million rats were slain in this
+campaign. Their breeding-places were destroyed by making cellars,
+woodsheds, warehouses, etc., rat-proof and removing all old rubbish.
+Garbage cans were installed in all parts of the city, as it was required
+that all garbage be stored where rats could not feed upon it, and
+altogether every effort was made to make it as uncomfortable as possible
+for the rats.
+
+The marked success attending this work abundantly confirms the soundness
+of the theory upon which it was based, and serves as another example of
+the way in which science is teaching us how to prevent or control many
+of our most serious diseases.
+
+
+THE INDIAN PLAGUE COMMISSION
+
+In 1896, what proved to be a very serious outbreak of plague, occurred
+in Bombay and spread to other parts of India. In 1898, a commission was
+appointed to inquire into the origin of the different outbreaks, the
+manner in which the disease is communicated, etc. This was known as the
+Indian Plague Commission, and its exhaustive report, together with the
+minutes of the evidence presented to the committee, represents a
+stupendous amount of work on this subject and is the basis for much of
+the later investigation that has been undertaken.
+
+After the consideration of the evidence from various sources the
+commission decided that the principal mode of infection both for man and
+rats was through some sort of an abrasion in the skin, although it
+recognized also the possibility of infection through the nose and
+throat, and possibly, very rarely, through the intestinal tract or other
+places.
+
+Considerable time was spent in considering Dr. Simond's claim, made in
+1898, that fleas which have been parasitic on plague-infected rats
+migrate on the death of their hosts and convey the infection to healthy
+men and rats. Dr. Simond sought to establish the following:
+
+     "Firstly, that plague rats are eminently infective when infected
+     with fleas and that they cease to be infective when they have been
+     deserted by their parasites: Secondly, that living plague bacilli
+     are found in association with fleas which are taken from
+     plague-infected rats: Thirdly, that plague can pass from infected
+     rats to other animals which have not come directly in contact with
+     them or with their infected excretions: Fourthly, that fleas which
+     infest rats will transfer themselves as parasites to men."
+
+After reviewing the experiments which had been made to establish these
+claims the commission believed that sufficient precaution had not been
+taken to prevent infection from other sources and that not enough
+definite evidence was produced. Against this claim much negative
+evidence was considered and the final conclusion was "that suctorial
+insects do not come under consideration in connection with the spread of
+plague."
+
+In 1905 another body of men known as the Advisory Committee was
+appointed to arrange for further studies in India and other places,
+particularly in relation to the mode of dissemination of the disease.
+They at once appointed a new working commission who immediately began
+their studies and experiments. The preliminary reports of their work,
+which are still known as the Reports of the Indian Plague Commission, as
+well as the reports of contributing investigations that are being made
+from time to time, have served to establish entirely Dr. Simond's claims
+and have completely revolutionized the methods of fighting plague.
+
+There are several different types of plague, seeming to depend largely
+on the manner of infection. The most common type is that known as the
+bubonic plague which is characterized by buboes or swellings in various
+parts of the body. This form of infection is usually received through
+the skin in some manner or other. Only rarely does direct man-to-man
+infection occur though there is always the possibility of it. The
+investigations have shown that the flea is the most common agent in
+transferring the disease from rat to rat or from rat to man. This may be
+accomplished by the flea transferring the bacilli directly from one host
+to another on its proboscis, or they may be carried in the alimentary
+canal of the flea and gain an entrance into the skin through an abrasion
+of some kind when the flea is crushed as it is biting, or when some of
+the bacilli are left on the skin in the excreta of the insect.
+
+
+RESULTS OF VERJBITSKI'S EXPERIMENTS
+
+A very important series of experiments bearing directly on this subject
+was made in 1902 and 1903 by Dr. D.T. Verjbitski. The paper giving the
+results of this work was not published in any scientific journal until
+1908 when the Advisory Committee published it in one of their reports.
+The experiments were so well planned and executed and the results so
+definite that I think it is worth while to give in full his summary of
+results. The bugs referred to are bedbugs.
+
+     "(1) All fleas and bugs which have sucked the blood of animals
+     dying from plague contain plague microbes.
+
+     "(2) Fleas and bugs which have sucked the blood of animals which
+     are suffering from plague only contain plague microbes when the
+     bites have been inflicted from 12 to 26 hours before the death of
+     the animals, that is, during that period of their illness when
+     their blood contains plague bacilli.
+
+     "(3) The vitality and virulence of the plague microbes are
+     preserved in these insects.
+
+     "(4) Plague bacilli may be found in fleas from four to six days
+     after they have sucked the blood of an animal dying with plague. In
+     bugs, not previously starved or starved only for a short time (one
+     to seven days), the plague microbes disappear on the third day; in
+     those that have been starved for four to four and one-half months,
+     after eight or nine days.
+
+     "(5) The numbers of plague microbes in the infected fleas and bugs
+     increase during the first few days.
+
+     "(6) The faeces of infected fleas and bugs contain virulent plague
+     microbes as long as they persist in the alimentary canal of these
+     insects.
+
+     "(7) Animals could not be infected by the bites of fleas and bugs
+     which had been infected by animals whose own infection had been
+     occasioned by a culture of small virulence, notwithstanding the
+     fact that the insects may be found to contain abundant plague
+     microbes.
+
+     "(8) Fleas and bugs that have fed upon animals which have been
+     infected by cultures of high virulence convey infection by means of
+     bites, and the more certainly so the more virulent the culture with
+     which the first animal was inoculated.
+
+     "(9) The local inflammatory reaction in animals which have died
+     from plague occasioned by the bites of infected insects is either
+     very slight or absent. In the latter case it is only by the
+     situation of the primary bubo that one can approximately identify
+     the area through which the plague infection entered the organism.
+
+     "(10) Infected fleas communicate the disease to healthy animals for
+     three days after infection. Infected bugs have the power of doing
+     so for five days.
+
+     "(11) It was not found possible for more than two animals to be
+     infected by the bites of the same bugs.
+
+     "(12) The crushing of infected bugs in situ during the process of
+     biting, occasioned in the majority of cases the infection of the
+     healthy animal with plague.
+
+     "(13) The injury to the skin occasioned by the bite of bugs or
+     fleas offers a channel through which the plague microbes can easily
+     enter the body and occasion death from plague.
+
+     "(14) Crushed infected bugs and fleas and their faeces, like other
+     plague material, can infect through the small punctures of the skin
+     caused by the bites of bugs and fleas, but only for a short time
+     after the infliction of these bites.
+
+     "(15) In the case of linen and other fabrics soiled by crushing
+     infected fleas and bugs on them, or by the faeces of these insects
+     the plague microbes can under favorable conditions remain alive and
+     virulent during more than five months.
+
+     "(16) Chemical disinfectants do not in the ordinary course of
+     application kill plague microbes in infected fleas and bugs.
+
+     "(17) The rat flea _Typhlopsylla musculi_ does not bite human
+     beings.
+
+     "(18) Human fleas do bite rats.
+
+     "(19) Fleas found on dogs and cats bite both human beings and rats.
+
+     "(20) Human fleas and fleas found on cats and dogs can live on rats
+     as casual parasites, and therefore can under certain conditions
+     play a part in the transmission of plague from rats to human
+     beings, and vice versa."
+
+
+RESULTS OF VARIOUS INVESTIGATIONS
+
+Various other plague commissions from other countries as well as many
+individuals have investigated the same subject, and the results all
+point conclusively to the fact that the rats and the fleas are at least
+the most important factors in the spread of the disease. The evidence
+from many sources and from many experiments may be briefly summed up as
+follows: The disease is caused by the presence in the system of minute
+bacteria, _Bacillus pestis_. It is probable that plague is primarily a
+disease of rats and only secondarily and accidentally, as it were, a
+disease of man.
+
+Rats are subject to the plague and are often killed by it in great
+numbers. An outbreak of plague among men is often preceded by a very
+noticeable outbreak among rats.
+
+Rats dying of the plague have their blood filled with the plague
+bacillus. Fleas or other suctorial insects feeding on such rats take
+myriads of these bacilli into their stomach and get many on their
+proboscis.
+
+The fleas usually leave a rat as soon as it dies and of course seek some
+other source of food. When such infected fleas are permitted to bite
+other rats or guinea-pigs these animals often develop the disease.
+Several of the species of fleas that infest rats will bite man also, and
+in the cases of many plague patients it can be definitely shown that
+they had recently been bitten by fleas.
+
+
+STRUCTURE AND HABITS OF FLEAS
+
+A study of the structure and habits of fleas shows that in many respects
+they are particularly adapted for spreading such a disease as bubonic
+plague. The piercing proboscis consists of three long needle-like
+organs, the epipharynx and mandibles, and a lower lip or labium. The
+mandibles have the sides serrate like a two-edged saw. The labium is
+divided close to its base so that it really consists of two slender
+four-segmented organs which lie close together and form a groove in
+which the piercing organs lie. When the flea is feeding, the epipharynx
+and mandibles are thrust into the skin of the victim, the labium serving
+as a guide. As the sharp cutting organs are thrust deeper and deeper the
+labium doubles back like a bow and does not enter the skin. Saliva is
+then poured into the wound through minute grooves in the mandibles, and
+the blood is sucked up into the mouth by the sucking organ which lies in
+the head at the base of the mouth-parts. Just above this piercing
+proboscis is a pair of flat, obtuse, somewhat triangular pieces, the
+maxillary blades or maxillae. When the proboscis is fully inserted into
+the skin the tips of these maxillae may also be embedded in the tissue
+and perhaps help to make the wound larger. Attached to these maxillae is
+a pair of rather stout, four-jointed appendages, the palpi. They
+probably act as feelers.
+
+If the flea chances to be feeding on a plague-infected rat or person
+many of the plague bacilli will get on the mouth-parts and myriads of
+them are of course sucked up into the stomach with the blood. Those on
+the proboscis may be transferred directly to the next victim that it is
+thrust into, and those in the stomach may be carried for some time and
+finally liberated when the flea is feeding again or when it is crushed
+by the annoyed host. The latter is probably the most common method of
+infection, for the bacilli that are liberated when the flea is crushed
+may readily be rubbed into the wound made by the flea bite or into
+abrasions of the skin due to the scratching. Kill the flea, but don't
+"rub it in."
+
+[Illustration: FIG. 105--Rat-flea (_Laemopsylla cheopis_); male.]
+
+[Illustration: FIG. 106--Rat-flea (_L. cheopis_); female.]
+
+[Illustration: FIG. 107--Head of rat-flea showing mouth-parts.]
+
+[Illustration: FIG. 108--Human-flea (_Pulex irritans_); male.]
+
+During the recent outbreak in San Francisco many thousand fleas that
+were infesting man, rats, mice, cats, and dogs, squirrels and other
+animals have been studied and it has been found that while each flea
+species has its particular host upon which it is principally found, few
+if any of them will hesitate to leave this host when it is dead and
+attack man or any other animal that may be convenient.
+
+
+COMMON SPECIES OF FLEAS
+
+Throughout India and in all the warm climates where plague frequently
+occurs the most common flea found on rats has come to be known as the
+plague flea (_Laemopsylla cheopus_) (Figs. 105, 106), and is doubtless
+the principal species that is concerned in carrying the disease in those
+climates. It now occurs quite commonly on the rats in the San Francisco
+Bay region and is occasionally found there on man also. In the United
+States, Great Britain and other temperate regions another larger
+species, _Ceratophyllus fasciatus_ is by far the most common flea found
+on rats, and is commonly known as the rat flea. It occurs on both the
+brown and the black rats _Mus norvegicus_ and _M. rattus_, on the house
+mouse and frequently on man. It has also been taken in California on
+pocket gophers and on a skunk.
+
+The common human flea (_Pulex irritans_) (Figs. 108, 109), is found in
+all parts of the inhabited world. Although we regard it primarily as a
+pest of human beings it often occurs very abundantly on cats, dogs, mice
+and rats as well as on some wild mammals such as badgers, foxes and
+others and has occasionally been found on birds.
+
+Most entomologists regard the fleas commonly found on cats and dogs as
+belonging to one species _Ctenocephalus canis_. Others believe them to
+be distinct species and call the cat flea _Ctenocephalus felis_. So far
+as our personal comfort and safety is concerned it makes but little
+difference to us whether the flea that bites us is called _canis_ or
+_felis_ for they both look very much alike, and act alike and the bite
+of one hurts just as much as the bite of the other. Although cats and
+dogs are their normal hosts they are very often troublesome household
+pests, sometimes making a house almost uninhabitable. They are
+frequently found on rats, and therefore may carry the plague bacillus
+from rat to rat or from rat to man.
+
+
+GROUND-SQUIRRELS AND PLAGUE
+
+As early as 1903 Dr. Blue, in charge of the plague suppressive measures
+in San Francisco, became impressed with the possibility of the common
+California ground-squirrels (_Otospermophilus beecheyi_), acting as an
+agent in the transmission of plague. It was rumored at that time that
+some epidemic disease was killing the squirrels in some of the counties
+surrounding San Francisco Bay, notably in Contra Costa County. None of
+the squirrels were examined at that time, but since then many thousand
+have been carefully studied and it has been definitely shown that many
+of them are plague-infected. Just how the plague got started among them
+will probably never be really known. There is little doubt, however, but
+that it was transferred in some way from the rats to the squirrels. The
+trains and the bay and river steamers running out from San Francisco
+would afford abundant opportunity for the rats to go from the city to
+the warehouses all along the shore. Once there they would use the same
+runways as the squirrels about the warehouses and in the near-by fields.
+In harvest time the rats migrate to the fields and make constant use of
+the squirrel holes. The farmers in some sections report that they
+frequently catch more rats than squirrels in traps set in squirrel holes
+at that season of the year.
+
+This close association of the rats and the squirrels affords a good
+opportunity for the fleas infesting them to pass from one host to the
+other.
+
+So far only two species of fleas have been recorded from the
+ground-squirrels. One, _Ceratophyllus acutus_, is very common, sometimes
+literally swarming over the squirrels, particularly if a squirrel is
+sick or weak from any cause. The other species, _Hoplopsyllus anomalus_,
+is less abundant but still quite common. Both of these species infest
+rats also, so the chain of evidence is practically complete. We have
+only to assume that at sometime one or more of the plague-infected rats
+found their way into the region where the squirrels were, and the fleas
+passing from the rats to the squirrels would carry the plague with them.
+
+The fact that the plague already has such a start among the squirrels
+opens a new and very serious phase of the problem of suppressing the
+disease. All who have hunted the ground-squirrels will testify to the
+readiness with which the fleas from them will bite those who are
+handling them. As it is the sick or weak squirrels that are most often
+taken there is always a chance that plague may be transferred from them
+to human beings. The records of the plague cases in California show at
+least three cases in which there seems to be very little doubt that the
+disease resulted from handling plague-infected squirrels.
+
+[Illustration: FIG. 109--Human-flea (_P. irritans_); female.]
+
+[Illustration: FIG. 110--Mouse-flea (_Ctenopsyllus musculi_); female.]
+
+A still more serious thing is the possibility of the disease remaining
+in a more or less virulent form among the squirrels for some time,
+possibly for years, and then breaking out again in some locality where
+the rats or men may become infected. As long as there is a trace of the
+disease among the squirrels there is always the chance of it spreading,
+so that new areas may become infested. Those in charge of the
+plague-suppressive measures are fully aware of these dangers and are
+making a careful study of the situation and will doubtless be able to
+cope with it successfully. It may be that the squirrels will have to be
+exterminated in the infected regions. This would be a long and difficult
+task, but the success attending the fight against the rats in a great
+city shows what can be done when the determination to do it is there.
+
+
+REMEDIES FOR FLEAS
+
+We have seen how a great city set to work to rid itself of the
+plague-sick rats. As a matter of fact it was not the rats that they
+were after primarily. If the rats had not harbored fleas the city would
+have been glad to let the disease take its course and destroy as many
+rats as possible. But it was found that the only way to get rid of the
+fleas that might possibly be infected with the plague was to kill their
+rat hosts.
+
+General cleaning-up measures will of course very materially lessen the
+number of fleas about the private dwellings, but there often remains a
+number of fleas in the house that are a source of great annoyance even
+if the danger is eliminated.
+
+Particularly is this apt to be so in places where cats or dogs are
+members of the household. These animals almost always harbor at least a
+few fleas, and where there are a few there is always a possibility, even
+a great probability, that there will be many more unless an effort is
+made to get rid of them.
+
+In some sections of the country it is the cat and dog flea that is the
+most troublesome to man. The minute white eggs of the fleas are usually
+laid about the sleeping-places of these animals and the slender active
+larvae that hatch from them feed upon any kind of organic matter that
+they can find in the dust or in the cracks and crevices. About eight or
+ten days after hatching the larvae spin delicate brownish cocoons in
+which they pass the pupal stage, issuing a few days later as the adult
+fleas.
+
+It will at once appear, then, that it is important to provide the cats
+and dogs with sleeping-places that can be kept clean. If they have a mat
+or blanket to sleep on this can be taken up and shaken frequently and
+the dust swept up and burned. In this way many of the eggs or larvae may
+be destroyed. Very often the dust under a carpet that has not been taken
+up and dusted for some time will be found to be harboring a multitude of
+fleas or their larvae. In such cases a thorough cleaning of the carpet
+and the floors will bring relief. Houses that are unused for some time
+during the summer months are often found to be overrun with fleas in the
+fall, for the fleas have had an unmolested opportunity to breed and
+multiply. Such rooms of course require a thorough cleaning or it is
+sometimes possible to kill the fleas by a liberal use of pyrethrum
+powder or benzine or to fumigate. In this connection, Dr. Skinner's note
+in the _Journal of Economic Entomology_ is worth repeating.
+
+     "In the latter part of last May (1908) I moved into a house that
+     had not been previously occupied. No carpet was used and being
+     summer only a few rugs were placed on the floors. A part of the
+     household consisted of a collie dog and three Persian cats. Very
+     soon the fleas appeared, the dog and cat flea, _Ctenocephalus
+     canis_. I did not count them and I can't say whether they numbered
+     a million or only a hundred thousand. On arising in the morning and
+     stepping on the floor one would find from three to a dozen on the
+     ankles. The usual remedies for fleas are either drastic or somewhat
+     unsatisfactory. The drastic one is to send the animals to the
+     institutions, where they are asphyxiated, or take the other advice,
+     'Don't keep animals.'
+
+     "I tried mopping the floors with rather a strong solution of
+     creolin but it did little good. Previous experience with pyrethrum
+     was not very satisfactory. Knowing the volatility of naphthalene in
+     warm weather and the irritating character of its vapor led me to
+     try it. I took one room at a time, scattered on the floor five
+     pounds of flake naphthalene and closed it for twenty-four hours. On
+     entering such a room the naphthalene vapor will instantly bring
+     tears to the eyes and cause coughing and irritation of the air
+     passages. I mention this to show how it acts on the fleas. It
+     proved to be a perfect and effectual remedy and very inexpensive,
+     as the naphthalene could be swept up and transferred to other
+     rooms. So far as I am concerned the flea question is solved and if
+     I have further trouble I know the remedy. I intend to keep the dog
+     and the cats."
+
+
+
+
+CHAPTER X
+
+OTHER DISEASES, MOSTLY TROPICAL, KNOWN OR THOUGHT TO BE TRANSMITTED BY
+INSECTS
+
+
+SLEEPING SICKNESS
+
+One of the worst scourges of Africa and one that is to-day attracting
+world-wide attention is the disease known as trypanosomiasis, the
+terminal phase of which is sleeping sickness, one of the most ghastly
+diseases that we know.
+
+Among the Protozoa referred to in one of the earlier chapters mention
+was made of certain trypanosomes which inhabit the blood of man and
+certain animals. Very little was known concerning these parasites
+previous to the beginning of the present century, but since that time
+several have been found to be of great economic importance. The group is
+being studied extensively and every day our knowledge of them is
+increasing so that we now know quite definitely the life-history of
+several.
+
+_Trypanosoma lewisi_, a parasite of rats, is perhaps the best known as
+it is always common where-ever rats are found. Sometimes as many as 30%
+or 40% of the rats of certain districts are infected. It is thought that
+these are transmitted from rat to rat by the common rat-louse which
+serves as an intermediate host. Fleas may also act as disseminating
+agents.
+
+A few other kinds cause serious disease of animals, but we are more
+interested just now in the particular one that is causing so much
+trouble in Africa. This parasite was discovered in 1902 and was named
+_Trypanosoma gambiensi_ (Fig. 111). Since then it has been found to be
+widely distributed. Although the natives have doubtless long been
+subject to the disease caused by this parasite, the recent influx of
+whites to these regions and the consequent movements of the natives have
+caused a great spread of the disease so that whole regions are now made
+desolate, the inhabitants dying or fleeing to escape the uncanny death.
+
+The disease may run its course in a few months or it may take years. The
+symptoms are various, but infection is usually soon followed by fevers,
+sometimes mild, sometimes severe, which recur at irregular intervals.
+Certain glands or other parts of the body may become swollen. More or
+less extensive skin eruptions occur on all parts of the body and the
+patient gradually becomes anemic and physically and intellectually
+feeble. The nervous system seems to be affected by the parasite, either
+directly or by the action of the toxins it produces. The patient becomes
+more debilitated and morose with an increasing tendency to sleep, hence
+the name sleeping sickness. As the stupor deepens the patient looses all
+desire or power of exertion and as little food is taken he rapidly
+wastes away and finally succumbs for after this final stage is reached
+there is no relief.
+
+It is definitely known that a species of tsetse-fly, _Glossina palpalis_
+(Fig. 112), which somewhat resembles our stable-fly, is responsible for
+the dissemination of the disease, and some recent investigators have
+suggested that certain species of mosquitoes may also carry the parasite
+from one host to another. There still remains some doubt as to the exact
+manner in which the fly transmits the disease, but it seems altogether
+likely that it is an alternative host and does not serve as a simple
+mechanical carrier. In this respect it is like the mosquito which is one
+of the necessary hosts of the malaria parasites, and unlike the
+house-fly which carries the germs of various diseases in a purely
+mechanical way without serving as a definite necessary host for the
+parasite.
+
+The tsetse-fly is found only in tropical Africa and is limited in its
+distribution there to certain very definite, narrow, brushy areas along
+the water's edge. If these places can be avoided there seems to be
+little danger. Those who are fighting the disease have found that if the
+brush in the vicinity of watering-places and ferry-landings is cleared
+away such places become comparatively safe. These flies do not lay eggs
+but produce full-grown larvae which soon pupate in the ground.
+
+
+ELEPHANTIASIS
+
+In many tropical regions human blood as well as that of other animals is
+the normal habitat of certain worm-like parasites (Nematodes). They are
+not entirely confined to the tropics but may extend far up into the
+subtropical regions. Five or six different species of these parasites
+are known, only one of which, however, has been shown to be of any
+pathological importance, as far as human beings are concerned.
+
+[Illustration: FIG. 111--_Trypanosoma gambiense_; various forms from
+blood and cerebrospinal fluid. (After Manson.)]
+
+[Illustration: FIG. 112--Tsetse-fly. (After Manson.)]
+
+This species, _Filaria bancrofti_, is not only very widely distributed,
+but in regions such as some of the South Sea Islands a very large per
+cent of the natives have the filariae present in their blood. When these
+parasites are withdrawn from the circulation and placed on a slide for
+study they are seen to be minute transparent, colorless, snake-like
+organisms inclosed in a very delicate sack or sheath. They are but a
+little more than one-hundredth of an inch long and about as big around
+as a red blood-corpuscle. These are the larval forms of the parasite and
+have been called by Le Dantec the micro-filaria.
+
+If blood of the patient drawn from the skin, is examined during the day
+few if any of these parasites are found, but if it is examined between
+five or six o'clock in the evening and eight or nine o'clock the next
+morning they may be found in numbers. During the daytime they have
+retired from the peripheral circulation to the larger arteries and to
+the lungs, where they may be found in great numbers.
+
+This night-swarming to the peripheral circulation has been found to be a
+remarkable adaptation in the life-history of the parasite, for it has
+been demonstrated that in order to go on with its development these
+larval forms must be taken into the alimentary canal of the mosquito.
+Most of the mosquitoes in which the development takes place are
+night-feeders, so that the parasites are sucked up with the blood of the
+victim. Once inside the stomach they soon free themselves from the
+inclosing sheath and make their way through the walls of the stomach and
+enter the muscular tissue, particularly the thoracic muscles. Here they
+undergo a metamorphosis and increase enormously in size, some attaining
+one-sixteenth of an inch in length.
+
+After sixteen to twenty days they leave these muscles and make their way
+to other parts of the body. A few may be found in different parts of the
+abdomen, but most of them make their way forward into the head of the
+mosquito and coil themselves up close to the base of the proboscis,
+finally finding their way down into the proboscis inside the labium.
+Here they lie until an opportunity offers for them to escape to the warm
+blood of a vertebrate. They probably pass through the thin membrane
+connecting the labella with the proboscis and there find their way into
+the wound made by the puncture when the insect bites. Whether these
+parasites can gain an entrance into the circulatory system in any other
+way is not known. It has been suggested that the mosquitoes dying and
+disintegrating on the surface of water may liberate the filariae which
+may later find their way into the system of the vertebrate host when the
+water is used for drinking, but most of the investigations made so far
+seem to indicate that they make their way directly from the proboscis
+into the new host.
+
+Soon after entering the circulatory system of the human host the
+parasites make their way into the lymphatics where they attain sexual
+maturity, and in due time new generations of the larval filariae or
+microfilariae are poured into the lymph, and finally into the definite
+blood-vessels, ready to be sucked up by the next mosquito that feeds on
+the patient.
+
+In most cases of infection the presence of these filariae in the blood
+seems to cause no inconvenience to the host. They are probably never
+injurious in the larval stage, that is, in the stage in which they are
+found in the peripheral circulation.
+
+In many cases, however, the presence of the sexual forms in the
+lymphatics may cause serious complications. The most common of these is
+that hideous and loathsome disease known as elephantiasis in which
+certain parts of the patient becomes greatly swollen and distorted. An
+arm or a leg may become swollen to several times its natural size, or
+other parts of the body may be seriously affected.
+
+In some of the South Sea Islands 30% to 40% of the natives are afflicted
+in this way, some only slightly others seriously. There is little or no
+pain, but in severe cases the distorted parts often render the patient
+entirely helpless.
+
+The exact way in which the parasites cause such swelling is not very
+definitely known. Manson, who has done more work on these diseases than
+any one else, believes that the trouble arises from the clogging of the
+lymphatic glands or trunks, thus cutting them off from the general
+circulation, in which case the affected parts may become distorted. This
+clogging of the passages is believed to be due to the presence of great
+numbers of immature eggs which have been liberated by parasites injured
+in some way before their eggs were entirely developed.
+
+This interference with the lymphatic circulation brings about the
+anomalous condition of a patient with a serious filarial disease with
+fewer of the filarial parasites in his blood than one who is not so
+seriously affected. This is supposed to be due to the fact that the
+disease-producing parasites have died and that the lymphatics have
+become so obstructed that any microfilariae they may contain cannot make
+their way into the general circulation. Such a patient then would not be
+as likely to infect a mosquito as would one less seriously affected.
+
+It has always been thought that little or nothing could be done in the
+way of successfully treating this disease, but quite recently a French
+physician, who has been conducting a long series of experiments in the
+Society Islands, announced that he is able to cure many cases by certain
+surgical operations on the affected parts.
+
+
+DENGUE OR "BREAKBONE FEVER"
+
+This is another disease of the tropics often occurring in widespread
+epidemics. It is probably most frequently met with in the West Indies,
+but may occur in any of the tropical countries or islands. Occasionally
+it spreads into subtropical or even temperate regions. Several extensive
+epidemics have occurred in the United States. Once introduced into a
+community it spreads very rapidly and nothing seems to confer immunity.
+
+The various names by which it has been called well describe its effect
+on the patient; breakbone fever, dandy-fever, stiff-necked or
+giraffe-fever, boquet (or "bucket") fever, _scarlatina rheumatica_,
+polka-fever, etc. While the suffering is intense as long as the disease
+lasts it seldom terminates fatally.
+
+It has always been classed as a very contagious disease and it has not
+yet been definitely shown that it is not. Recent observations, however,
+have shown that it is probably caused by a certain Protozoan parasite
+that is found in the blood of dengue patients and several experiments
+have been conducted by Dr. Graham which seem to indicate that it is
+transmitted by mosquitoes. In these experiments, _Culex fatigans_, a
+common tropical or subtropical mosquito, was used. The same parasite
+that is found in the human blood may be found in the stomach and blood
+of the mosquitoes up to the fifth day after it has fed on a dengue
+patient.
+
+Sick and healthy individuals were allowed to remain in close contact in
+a room from which the mosquitoes had been excluded, and the disease was
+not spread. Mosquitoes that had bitten dengue patients were taken to a
+higher region where dengue had never occurred and allowed to bite two
+healthy persons. Both developed the disease and as they were protected
+from other mosquitoes until they had recovered, the disease did not
+spread to others of the community. These and other observations seem to
+make a complete chain of evidence, and most medical men to-day accept
+the theory as well proved and in their practice take every precaution to
+prevent the spread of the disease by keeping the infected patient from
+being bitten by the mosquitoes.
+
+The yellow fever mosquito is also suspected of carrying this same
+disease, and it is possible that other species are also concerned. If
+it is true that the parasite can be carried by several different species
+of mosquitoes this would account very largely for its rapid spread
+wherever it is introduced into a community. Where it occurs outside the
+tropics it is only in the warm summer months when mosquitoes are always
+abundant.
+
+
+MALTA OR MEDITERRANEAN FEVER
+
+This is also a tropical and subtropical disease that occasionally gets
+up into the temperate region, sometimes occurring in the United States.
+The fever begins with a severe headache, and other symptoms follow. It
+is usually of the remittent type and may continue for some months.
+
+It is caused by minute bacteria (_Micrococcus melitensis_) and is a very
+infectious but not usually contagious disease. The germ is readily
+conveyed by inoculation, and several investigators have sought to show
+that the mosquito often serves as the inoculating agent. The disease is
+especially prevalent during the mosquito season, and has twice been
+conveyed to monkeys by infected insects.
+
+
+LEPROSY
+
+This loathsome disease has long been known to be caused by a particular
+bacillus (_Bacillus leprae_), but the way in which this organism gains
+an entrance into the system is still unknown. Many theories have been
+propounded, but none of them has been well established. Within recent
+years the possibility of insects carrying the germ and in one way or
+another transmitting it to healthy individuals has been suggested and
+much discussed. As the leprae bacilli are present in the skin and ulcers
+of leprous patients, insects sucking the blood or feeding on the sores
+could not help taking some of them into their body or becoming
+contaminated. These bacilli have been found at various times in the
+stomach or intestine of mosquitoes, fleas and bedbugs. So it is believed
+by some that these and other insects, such as lice and flies, may
+sometimes transmit the disease. On a previous page we have referred to
+the possibility of the face-mites acting as disseminators of leprosy.
+
+Leprosy occurs most commonly among people where little attention is paid
+to bodily cleanliness. Such people are usually freely infested with
+various parasites that thrive well in the filth, so if the germs can be
+transmitted in this way the carriers are there in abundance.
+
+The fact that the sores usually occur on exposed parts of the body has
+been pointed to as evidence that inoculation is due to such insects as
+flies and mosquitoes. It has been noted that leprosy is frequently very
+common in regions where elephantiasis occurs, suggesting the possibility
+of the same carrier, the mosquito, for both diseases. So while there is
+as yet very little evidence one way or the other, insects that are found
+around leprous patients are to be regarded with suspicion, for until we
+know more definitely just how the disease is communicated the insects
+must be looked on as possible sources of contamination.
+
+
+KALA-AZAR OR DUM-DUM FEVER
+
+This is a very fatal infectious disease of many tropical and subtropical
+regions, spreading terror among the natives wherever it occurs. It is
+caused by the presence in the system of Protozoan parasites, the
+so-called Leishman-Donovan bodies, that have recently been studied by
+several observers.
+
+Dr. W.S. Patton of the Indian Medical Service has been making some
+extensive experiments with the common bedbug of India (_Cimex
+rotundatus_) which seem to demonstrate fully that this insect is
+responsible for the transmission of the parasite that causes the
+disease. He has found the parasite in all stages of development in the
+bedbug. This, taken with a number of other observations in regard to the
+tendency of the disease to cling to particular houses, makes a strong
+case against the bedbug. Manson, however, believes that the parasite may
+be transmitted by other agents also, possibly by means of flies that
+visit the sores or in other ways.
+
+
+ORIENTAL SORE
+
+This disease, once supposed to be confined to the Orient, is now found
+to be rather widely distributed throughout the tropics, where it is
+sometimes very prevalent. It is caused by the presence in the system of
+a parasite very similar to or identical with the one causing _kala-azar_
+and is regarded by some as a modified form of that disease. The patient
+is affected with one or more serious sores or ulcers which usually occur
+on exposed parts of the body.
+
+The parasite that causes the disease is supposed to be carried by
+insects either directly or indirectly.
+
+In the latter case the insect may act as an intermediate host.
+
+Dogs and camels are also attacked by this disease and may be sources of
+infection.
+
+
+
+
+BIBLIOGRAPHY
+
+
+A complete list of books and articles dealing more or less directly with
+the subjects discussed in this book would be too extended for use here.
+For the past ten or twelve years many of the medical and biological
+journals have contained articles in almost every issue, discussing these
+subjects in some of their phases. I have selected only a few of the more
+important of them, and these only the English ones, confining myself
+mostly to those that I have personally consulted, and giving brief
+annotations. Many of these will be found to include very full
+bibliographies of the particular subject treated.
+
+In order to avoid repetition, references are given under one head only
+although many might properly be included in other sections as well.
+
+
+PARASITES AND PARASITISM
+
+     BRAUN, MAX. Animal Parasites of Man. Translated by Pauline Falcke
+     and edited by L.W. Sambon and F.V. Theobald. Third edition, 1906. A
+     chapter on the general subject of parasitism and a description of
+     parasites of all classes. Bibliography.
+
+     LEUCKART, R. The Parasites of Man and the Diseases Induced by Them.
+     Eng. transl., London, 1886.
+
+     NEUMAN, THEO. Entoparasites and Hygiene. _Trans. Vassar Bros.
+     Institute_, VII, 1895. A general discussion of parasitism;
+     life-history of some common parasites that infest man.
+
+     NEUMANN, L.G. Treatise on the Parasites and Parasitic Diseases of
+     the Domesticated Animals. Eng. transl. by Fleming, 1892.
+
+     RANSOM, B.H. How Parasites Are Transmitted. _Year Book U.S. Dept.
+     Agric._, 1905, pp. 139-166 (pub. 1906). Discusses the ways in which
+     parasites of all classes are transmitted.
+
+     SAMBON, L. The Part Played by Metazoan Parasites in Tropical
+     Pathology. _Jour. Trop. Med. & Hyg._, Vol. XI, Jan. 15, 1908. A
+     comprehensive discussion of this subject.
+
+     SHIPLEY, A.E., AND FEARNSIDES, E.G. Effects of Metazoan Parasites
+     on Their Hosts. _Jour. Econom. Biology_, Vol. I, 1906, pp. 41-62.
+     Discusses injury due to mere presence of parasite in host; to the
+     migration of the parasite; loss to host by feeding of parasites;
+     injury by certain toxins.
+
+     STILES, C.W. Diseases Caused by Animal Parasites. _Osler's Mod.
+     Med._, Vol. I, 1907, p. 525. General discussion; Trematodes;
+     Cestodes; Roundworms; Acariasis; Parasitic Insects; Myiasis.
+
+     VAN BENEDEN, P.J. Animal Parasites and Messmates. 1889. Contains
+     much that is interesting.
+
+     WARD, HENRY B. Influence of Parasitism on the Host. _Proc. Amer.
+     Assn. for Advancement of Science_, Vol. 56, 1907. A comprehensive
+     statement of this subject. List of literature.
+
+
+PROTOZOA
+
+     CALKINS, G.N. The Protozoa. _Osler's Mod. Med._, Vol. I, 1907, p.
+     353. General notes on the Protozoa; classification; reproduction;
+     life-cycle of various forms. Regards Protozoa as subkingdom and the
+     four great divisions as phyla.
+
+     CALKINS, G.N. Protozooelogy. N.Y., 1909. Chapters on parasitism,
+     pathogenic Protozoa, etc.
+
+     CLARKE, J.J. Protozoa and Disease. London, 1903, Pt. I. Discusses
+     the various protozoa that cause disease, and refers frequently to
+     those that are transferred from host to host by insects.
+
+     CLARKE, J.J. Protozoa and Disease. London, 1908. Part II,
+     comprising sections on the causation of smallpox, syphilis and
+     cancer. Notes on parasitic Protozoa, tropical diseases, ticks,
+     piroplasmosis, etc.
+
+     DANIELS, C.W. Persistence of the Tropical Diseases of Man Due to
+     Protozoa. _Jour. Trop. Med. & Hyg._, 12, Aug. 2, 1909, pp. 232-234.
+     Same in _Lancet_, II, 1909, p. 460. Good summary of present
+     knowledge of the subject.
+
+     MINCHIN, E.A. Protozoa. In Albutt and Rolleston's _System of
+     Medicine_, II, 1907, pp. 9-122. A comprehensive chapter on
+     Protozoa. Many parasitic forms are figured and described.
+     Bibliography.
+
+     MINCHIN, E.A. The Sporozoa. In Lankester's _Treatise on Zooel._, Pt.
+     I, pp. 150-360, 1903. Best account of this group, list of Sporozoan
+     hosts. Bibliography.
+
+
+BACTERIA
+
+     FLEXNER, SIMON. Relation of Bacteria and Sporozoa to Disease.
+     _Science_, N.S., Vol. 27, No. 682, pp. 133-136. On these pages
+     discusses relation of bacteria and Protozoa to human diseases.
+
+     JORDAN, EDWIN O. General Bacteriology. Philad., 1898. A good
+     general treatment of the subject.
+
+     LEVY, ERNST, AND KLEMPERER, FELIX. Elements of Clinical
+     Bacteriology for Physicians and Students (transl. by A.A. Eschner),
+     Philad., 1909. Morphology and biology of bacteria; infection;
+     immunity; specific diseases of bacterial origin, etc.
+
+     MUIR, ROBT., AND RITCHIE, JAS. Manual of Bacteriology. N.Y., 1903.
+     Contains chapter on the relation of bacteria to diseases and
+     discussion of several bacterial diseases.
+
+     STERNBERG, G.M. A Manual of Bacteriology. N.Y., 1893. Part III is
+     devoted to pathogenic bacteria.
+
+
+INSECTS AND DISEASE
+
+     HERMS, W.B. Medical Entomology, Its Scope and Methods. _Jour. of
+     Eco. Ento._, Vol. 2, No. 4, 1909, pp. 265-268.
+
+     HOWARD, L.O. Insects as Carriers and Spreaders of Disease. _Year
+     Book U.S. Dept. Agric._, 1901, pp. 177-192. Good review of the
+     subject.
+
+     HOWARD, L.O. How Insects Affect Health in Rural Districts. _U.S.
+     Dept. Agric., Farmers' Bulletin, No. 155_, 1902. Discussion of city
+     and county conditions; protection from typhoid, malaria and yellow
+     fever.
+
+     HOWARD, L.O. Economic Loss to the People of U.S. Through Insects
+     That Cause Disease. _Bull. 78, U.S. Dept. Agric. Bur. of Ent._,
+     1909. A comprehensive discussion and summary of the subject.
+     Discusses mosquitoes, flies, the Panama Canal, epidemic diseases
+     and the progress of nations.
+
+     KELLOGG, V.L. Insects and Disease, Chap. XVIII, in _American
+     Insects_, pp. 615-654, 1905. Discusses Mosquitoes and malaria;
+     yellow fever and filariasis.
+
+     KING, H.H. Report on Economic Entomology of Khartoum, in _Third
+     Rept. of Wellcome Research Lab._, 1908. Discusses insects injurious
+     to man: mosquitoes, blood-sucking insects other than mosquitoes,
+     etc.
+
+     MASON, C.F. The Spread of Diseases by Insects, with Suggestions
+     Regarding Prophylaxis. _International Clinics_, Vol. II, 1904, pp.
+     1-21. A brief summary of the subject.
+
+     MCCRAE, JOHN. Recent Progress in Tropical Medicine. _International
+     Clinics_, Vol. II, 1904, pp. 22-36. Discusses several diseases,
+     some of which are transmitted by insects.
+
+     NUTTALL, G.H.F. On the Role of the Insects Arachnids and Myriapods
+     as Carriers in the Spread of Bacterial and Parasitic Diseases of
+     Man and Animals. A critical and historical study. _Johns Hopkins
+     Hospital Reports_, Vol. 8, 1899, pp. 1-154. A review of all the
+     literature up to this date. Important article.
+
+     NUTTALL, G.H.F. Insects as Carriers of Disease. Recent advances in
+     our knowledge of the part played by blood-sucking arthropods
+     (exclusive of mosquitoes and ticks) in the transmission of
+     infectious diseases. Bericht ueber den XIV. Intern. Kongress fuer
+     Hygiene und Dermogrophic. Berlin, 1907, pp. 195-206. Discusses
+     protozoan and bacterial diseases.
+
+     STILES, C.W. Insects as Disseminators of Disease. _Virginia Medical
+     Semi-monthly_, Vol. 6, No. 3, May 10, 1901, pp. 53-58. Good
+     statement of subject with list of recent workers.
+
+     WHERRY, W.B. Insects and Infection. _Cal. State Jour. of Med._,
+     Nov., 1907. Discusses the role of insects, ticks, etc., in the
+     transmission of infectious diseases.
+
+     Symposium on Yellow Fever and Other Insect-borne Diseases.
+     _Science_, N.S., Vol. 23, Nos. 584-585, 1906. The Protozoan
+     Life-cycle, G.N. Calkins. Filariasis and Trypanosome Diseases, H.B.
+     Ward. The Practical Results of Reed's Findings on Yellow Fever
+     Transmission, J.H. White. Difficulties of Recognition and
+     Prevention of Yellow Fever, Q. Kohnke. The Practical Side of
+     Mosquito Extermination, H.C. Weeks. Without Mosquitoes There Can Be
+     No Yellow Fever, Jas. Carroll. Estivo-autumnal Fever, Cause,
+     Diagnosis, Treatment and Destruction of Mosquitoes Which Spread the
+     Disease, H.A. Veazie.
+
+
+MOSQUITOES--SYSTEMATIC AND GENERAL
+
+     BALFOUR, ANDREW, AND STAFF. _Second Report of the Wellcome Research
+     Laboratories at the Gordon Memorial College_, Khartoum, 1906.
+     Includes reports on work on mosquitoes and other noxious insects.
+
+     BOYCE, SIR ROBERT W. Mosquitoes or Man? The Conquest of the
+     Tropical World. N.Y., 1909. Reviews medical and sanitary work in
+     the tropics and discusses the relation of insects to various
+     tropical diseases.
+
+     BUSCH, AUGUST. Report on a Trip for the Purpose of Studying the
+     Mosquito Fauna of Panama. _Smith. Miscell. Coll._, Vol. 5, Pt. I,
+     1908, p. 49. Work that is being done in Panama to control the
+     mosquitoes. Annotated list of species.
+
+     FELT, E.P. Mosquitoes or Culicidae of New York State. In _N.Y. State
+     Museum Bull. 79_, Entomology 22, 1904. Discusses distribution,
+     migration and life-history of various species of mosquitoes and
+     mosquito diseases. Bibliography.
+
+     GILES, GEO. M. A Handbook of Gnats or Mosquitoes, Giving the
+     Anatomy and Life-History of the Culicidae. London, 1902. Whole
+     subject treated very fully.
+
+     GRUBBS, S.B. Vessels as Carriers of Mosquitoes. _Pub. Health and
+     Mar. Hospt. Ser. Bull._ II, Mar. 3, 1903. Believes that mosquitoes
+     may come aboard when the vessel is lying at anchor one-half mile
+     from shore, and that under favorable conditions they may come
+     aboard when the vessel is fifteen miles from shore.
+
+     HOWARD, L.O. Mosquitoes. _Osler's Mod. Med._, Vol. I, p. 370, 1907.
+     General notes on classification and habits particularly in relation
+     to diseases.
+
+     HOWARD, L.O. Notes on Mosquitoes of the United States. _U.S. Dept.
+     Agric., 1900. Div. of Ento. Bull. No. 25_, N.S. Account of the
+     structure; biology; remarks on remedies.
+
+     HOWARD, L.O. Concerning the Geographic Distribution of the Yellow
+     Fever Mosquito. _Public Health Rept., Pub. Health and Mar. Hospt.
+     Ser._, Nov. 13, 1903. The same revised to Sept. 10, 1905.
+
+     HOWARD, L.O. Mosquitoes: How They Live; How They Carry Disease;
+     How They Are Classified; How They May Be Destroyed. N.Y., 1901. One
+     of the best popular books on mosquitoes.
+
+     MCCRACKEN, I. _Anopheles_ in California, with a Description of a
+     New Species. _Entomological News_, Vol. 15, Jan., 1904. Records of
+     three species, their breeding-places, habits, etc.
+
+     MITCHELL, EVELYN G. Mosquito Life. N.Y., 1907. A good popular
+     account of the mosquitoes and their relation to disease. The
+     appendix treats of mosquitoes and their possible relation to
+     leprosy.
+
+     SMITH, J.B. Mosquitoes Occurring Within the State of New Jersey.
+     Report of the New Jersey State Agric. Exper. Station upon the
+     mosquitoes occurring within the State. Trenton, N.J., 1904. Habits,
+     development, relation to disease, checks and remedies; systematic.
+
+     SMITH, J.B. The General Economic Importance of Mosquitoes. _Popular
+     Science Monthly_, 70, 1907, pp. 325-329. Mosquitoes affect not only
+     the health and comfort of the people, but hinder development of
+     agriculture and thus affect land values.
+
+     SMITH, J.B. The New Jersey Salt-marsh and Its Improvement. _New
+     Jersey Agricultural Experiment Station Bulletin_, 207, 1907. Shows
+     that the increased value of the land drained in the antimosquito
+     crusade more than pays for the cost of the drainage.
+
+     THEOBALD, F.V. Monograph of _Culicidae_ of the World. Four Vols. and
+     one Vol. of plates. London, 1901 to 1907. Vol. I contains 96 pages
+     on structure, life-history, habits, etc. Vol. II contains a
+     bibliography. Vol. Ill contains a list of species that carry
+     disease.
+
+     THEOBALD, F.V. Mosquitoes or _Culicidae_. In Albutt and Rolleston's
+     _System of Medicine_, II, 1907, pp. 122-168. Structure,
+     life-history, habits, distribution and classification of
+     mosquitoes. Bibliography.
+
+
+MOSQUITO ANATOMY
+
+     BERKELEY, WM. M. Laboratory Work with Mosquitoes. N.Y., 1902.
+     Chapters on development, anatomy, dissection, malarial parasites,
+     filarial disease, yellow fever.
+
+     DIMMOCK, GEO. Anatomy of the Mouth-parts and Suctorial Apparatus of
+     _Culex_. _Psyche_, 3, pp. 231-241, Sept., 1881. Good.
+
+     IMMS, A.D. On the Larval and Pupal Stages of _Anopheles
+     maculipennis_. _Journal Hygiene_, Vol. 7, No. 2, April, 1907.
+     Morphology.
+
+     IMMS, A.D. On the Larval and Pupal Stages of _Anopheles
+     maculipennis_. _Parasitology_, Vol. I, No. 2, June, 1908.
+     Continuation of article in _Jour. Hyg._, Vol. 7, No. 2. Continues
+     discussion of morphology.
+
+     NUTTALL, GEO. F., CORBETT, LOUIS, AND STRANGEWAYS-PIG, T. Studies
+     in Relation to Malaria. Pt. I, The Geographical Distribution of
+     _Anopheles_ in Relation to the Former Distribution of Ague in
+     England. _Jour. Hyg._, Vol. I, No. 1, Jan., 1901.
+
+     NUTTALL, GEO. F., AND SHIPLEY, ARTHUR E. Studies in Relation to
+     Malaria. Pt. II, Structure and Biology of _Anopheles_, _Jour Hyg._,
+     Vol. I, No. 1, Jan., 1901: The Egg and Larva; Bibliography. Pt. II,
+     cont, Vol. I, No. 2, April, 1901: The Pupa. Pt. II, cont., Vol. I,
+     No. 4, Oct., 1901: Adult External Anatomy. Pt. II, cont., Vol. 2,
+     No. 1, Jan., 1902: AEtiology of Adult. Pt. II, cont., Vol. Ill, No.
+     2, April, 1903: Anatomy of Adult.
+
+     THOMPSON, MILLETT T. Alimentary Canal of the Mosquito. _Proc. Bost.
+     Soc. Nat. Hist._, Vol. 32, No. 6, 1905, pp. 145-202. Good summary
+     of recent investigations.
+
+     WESCHE, W. The Mouth-parts of _Nemocera_ and Their Relation to the
+     Other Families of _Diptera_. _Royal Microscopic Soc. Jour._, 1904,
+     pp. 28-47. Discussion with illustrations of the mouth-parts of
+     various _Diptera_.
+
+
+MOSQUITOES--LIFE-HISTORY AND HABITS
+
+     AYERS, E.A. The Secrets of the Mosquito. A guide to the
+     extermination of the prolific pest. _World's Work_, 1907, Vol. 14,
+     pp. 8902-8910. Notes on life-history and methods of control.
+
+     JORDAN, E.O., AND HEFFERAN, MARY. Observations on the Bionomics of
+     _Anopheles_. _Jour. Infec. Diseases_, II, 1905, pp. 56-69.
+     Occurrence, breeding-places, habits, etc.
+
+     MORGAN, H.A., AND DUPREE, J.W. Development and Hibernation of
+     Mosquitoes. _Bull. 40_, N.S., _Div. of Ento._, pp. 88-92, 1903.
+     Results of observation on five genera of mosquitoes in the vicinity
+     of Baton Rouge, La.
+
+     ROSS, E.H. The Influence of Certain Biological Factors on the
+     Question of the Migration of Mosquitoes. _Jour. Trop. Med. & Hyg._,
+     12, 1909, pp. 256-258, Sept. 1. Only fecundated females feed on
+     blood, and must be fertilized after each batch of eggs. This
+     determines largely the time and place of breeding.
+
+     SMITH, J.B. Concerning Migration of Mosquitoes. _Science_, 18, Dec.
+     11, 1903, pp. 761-764. Observations on the migrations of
+     mosquitoes, particularly _C. sollicitans_.
+
+
+MOSQUITO FIGHTING
+
+     CELLI, ANGELO. The Campaign Against Malaria in Italy. Transl. by
+     J.J. Eyre. _Jour. Trop. Med. & Hyg._, XI, Apr. 1, 1908, pp.
+     101-108. Includes a good discussion of the effectiveness of
+     destroying the mosquitoes in controlling malaria.
+
+     FELT, E.P. Mosquito Control. In _Report of the N.Y. State
+     Entomologist for 1905_, pp. 109-116. Notes on importance and
+     methods of control of various species.
+
+     GOLDBERGER, JOS. Prevention and Destruction of Mosquitoes. _Public
+     Health Reports, Pub. Health and Mar. Hospt. Ser._, July 17, 1908.
+     Life-histories and methods of fighting larvae, pupae and adults.
+
+     LE PRINCE, J.A. Mosquito Destruction in the Tropics. _Jour. Amer.
+     Med. Assn._, LI, p. 26, Dec. 26, 1908. Occurrence and habits of
+     _Anopheles_, methods of destruction. Results of anti-malarial work
+     on the isthmus. Discussion by various doctors.
+
+     QUAYLE, H.J. Mosquito Control Work in California. _Bull. No. 178,
+     Calif. Agric. Ex. Sta._, pp. 1-55, 1906. Habits and life-history of
+     California species, with an account of experiments to control the
+     salt-marsh species.
+
+     ROSENAN, M.J. Disinfection Against Mosquitoes with Formaldehyde and
+     Sulphur Dioxid. _Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull.
+     6_, 1901.
+
+     ROSS, RONALD. Mosquito Brigades and How to Organize Them. New York,
+     1902.
+
+     ROSS, RONALD. Logical Basis of the Sanitary Policy of Mosquito
+     Reduction. _Science_, N.S., Vol. 22, No. 750, Dec. 1, 1905, pp.
+     689-699. Important article dealing with the methods of control.
+
+     SMITH, J.B. Salt-marsh Mosquitoes. _New Jersey Agric. Exper. Stn.
+     Special Bulletin T_, 1902. Breeding-places and methods of control
+     of this species.
+
+     SMITH, J.B. Mosquitocides. _Bull. 40, New Series U.S. Dept. Agric.,
+     Div. of Ento._, pp. 96-108, 1903. Results of experiments with a
+     number of substances, several of which were found to be effective
+     and some cheap enough to permit of their use to a limited extent.
+
+     SMITH, J.B. The New Jersey Salt-marsh and Its Improvement. _Bull.
+     No. 207_, Nov. 14, 1907, _New Jersey Agric. Exper. Stn._ Results of
+     draining the marshes to get rid of mosquitoes.
+
+     SMITH, J.B. The House Mosquito: a City, Town and Village Problem.
+     _N.J. Agric. Ex. Stn. Bull. 216_, 1908. Work done on salt-marshes
+     since 1904 practically eliminated the migratory species, so that
+     _C. pipens_, the house mosquito, is now the problem. Life-history
+     and methods of combating.
+
+     UNDERWOOD, W.L. Mosquitoes and Suggestions for Their Extermination.
+     _Pop. Sci. Mo._, Vol. 63, 1903, pp. 453-466. Life-history, habits
+     and methods of control.
+
+     UNDERWOOD, W.L. The Mosquito Nuisance and How to Deal with It.
+     Boston, 1903.
+
+     First Antimosquito Convention, 1903. Pub., Brooklyn, 1904. Contains
+     articles on what railroads, government and laws should do toward
+     mosquito extermination; mosquito work in Havana; how state
+     appropriations should be used, etc.
+
+     National Mosquito Extermination Society. Bulletin No. 1, 1904.
+     Object of Society; brief sketches of Ross, Reed, and others.
+     Reprints of a few articles on mosquito extermination.
+
+     American Mosquito Extermination Society. _Year Book for 1904-05._
+     N.Y., 1906. Containing reports of meetings and discussions of
+     various problems. Several interesting papers, among them "Criminal
+     Indictment of the Mosquito," F.W. Moss. "Mosquito Work at Panama
+     Canal," W.C. Sorgas. "Diversities Among New York Mosquitoes," E.P.
+     Felt. "Mosquito Extermination in New Jersey," J.B. Smith. "The
+     Mosquito Question," Quitman Kohnke.
+
+     Antimalarial Work in the Panama Canal Zone. Editorial in _Jour.
+     Trop. Med. & Hyg._, XI, Aug. 15, 1908, p. 251. Notes on the success
+     of the measures adopted there.
+
+
+MOSQUITOES AND DISEASE
+
+     DOTY, A.H. The Mosquito, Its Relation to Disease and Its
+     Extermination. _New York State Journal of Medicine_, May, 1908.
+
+     FINLAY, CHAS. Mosquitoes Considered as Transmitters of Yellow Fever
+     and Malaria. _Med. Record_, May 27, 1899, pp. 737-739. Review of
+     his theory in regard to mosquitoes and disease and the probable
+     necessary changes in view of recent discoveries.
+
+     HOWARD, L.O. Mosquitoes as Transmitters of Disease. _Review of
+     Reviews_, XXIV, 1901, pp. 192-195. A review of the work of various
+     investigators.
+
+     SMITH, J.B. Sanitary Aspect of the Mosquito Question. _Medical
+     News_, Mar. 7, 1903. Note on mosquitoes and their relation to
+     disease.
+
+     TAYLOR, J.B. Observations on the Mosquitoes of Havana, Cuba.
+     Reprint from _La Revista de Medicina_, June, 1903, p. 27.
+
+
+MALARIA
+
+     BANKS, C.S. Experiments in Malarial Transmission by Means of
+     _Myzomyia ludlowii_. _Phil. Jour. Sci._, B. 2, 1907, pp. 513-535.
+     Breeding-places of mosquitoes, life-histories of the species;
+     mosquitoes and malaria.
+
+     CRAIG, C.F. Malarial Fevers. _Osler's Mod. Med._, Vol. I, p. 392,
+     1907. Historical; distribution; malarial parasites; classification;
+     development; malarial mosquitoes; pathology; treatment, etc.
+
+     CRAIG, C.F. Studies in the Morphology of Malarial Plasmodia after
+     the Administration of Quinine and in Intracorpuscular Conjugation.
+     _Jour. Infec. Diseases_, VII, No. 2, 1910. See also same, IV, 1907,
+     pp. 108-140. Gives the evidence upon which he bases his theory of
+     the meaning of intracorpuscular conjunction.
+
+     CRAIG, C.F. The Malarial Fevers, Hemoglobinuric Fever and the Blood
+     Protozoa of Man. N.Y., 1909. A thorough consideration of the
+     subject of malaria and good discussion of the other subjects noted
+     in title. Bibliography.
+
+     DEADERICK, W.H. Malaria. Philad., 1909. The chapter on aetiology
+     treats of the transmission by mosquitoes.
+
+     HARRIS, S. Prevention of Malaria. _Jour. Amer. Med. Assn._, 53,
+     Oct. 9, 1909, pp. 1162-67. Effects of malaria, transmission by
+     mosquitoes, etc. In the discussion of the paper J.H. White
+     summarizes the fight against yellow fever in New Orleans.
+
+     HERRICK, G.W. Relation of Malaria to Agriculture and Other
+     Industries of the South. Economic losses occasioned by malaria;
+     malaria responsible for more sickness among the white population
+     than any other disease; relation to mosquitoes. _Pop. Sci. Mo._,
+     Vol. 62, Apr., 1903, pp. 521-525.
+
+     JONES, ROSS, ELLETT. Malaria. London, 1907. Small book,
+     introduction by Ross. Malaria in Greece and Italy; shows how this
+     disease contributed to the downfall of great nations.
+
+     MANNABERG, JULIUS. Malaria. In Nothnagel's _Encyclopedia of
+     Practical Med._, Amer. Ed., 1905, pp. 17-494. A very comprehensive
+     discussion of the disease and the relation of mosquitoes to the
+     malarial parasite.
+
+     MANSON, PATRICK. The Mosquito and the Malaria Parasite. _Brit. Med.
+     Jour._, Vol. II for 1898, pp. 849-853. History of the parasite in
+     the human and insect host; observations of Ross and others and
+     their meaning.
+
+     MANSON, PATRICK. Experimental Demonstration of the
+     Mosquito-malarial Theory. _Brit. Med. Jour._, Vol. 2 for 1900, pp.
+     949-951, also _Lancet_, II, 1900, pp. 923-925. Infected mosquitoes
+     sent from Rome allowed to bite men in England who had not been in
+     malarial regions. Malarial fever followed.
+
+     MANSON, PATRICK. Malarial Fever. Appendix to Vol. IX of T.C.
+     Albutt's _System of Med._, 1900. Relation of the malarial parasite
+     to the disease and to mosquitoes.
+
+     ROBERTSON, E.W. Renaming of Malaria--Anophelesis. _Va. Medical
+     Semi-monthly_, Sept. 10, 1909. Considers malaria a misnomer and
+     gives reasons for suggesting new name.
+
+     ROSS, RONALD. On Some Peculiar Pigmented Cells Found in Two
+     Mosquitoes Fed on Malarial Blood. _Brit. Med. Jour._, 1897, Dec.
+     18, p. 1786. Records in his experiments in feeding mosquitoes on
+     blood of malarial patients. Records finding the parasites in some
+     of them. Important article.
+
+     ROSS, RONALD. Pigmented Cells in Mosquitoes. _Brit. Med. Jour._,
+     1898, Feb. 26, p. 550. Further notes on them.
+
+     ROSS, RONALD. The Mosquito Theory of Malaria. Report dated
+     Calcutta, Feb. 16, 1899. Reprinted in _Pop. Sci. Monthly_, Vol. 56,
+     Nov., 1899, pp. 42-46. Tells of his investigations in India and
+     their results.
+
+     ROSS, RONALD. The Relationship of Malaria and the Mosquito.
+     _Lancet_, II, 1900, July 7, p. 4880. Observation on the
+     transmission of malaria.
+
+     ROSS, RONALD. Malaria Fever, Its Cause, Prevention and Treatment.
+     London, 1902. Chapters on malaria, mosquitoes, prevention and
+     treatment.
+
+     ROSS, RONALD. Parasites of Mosquitoes. _Jour. of Hyg._, VI, No. 2,
+     Apr., 1906. Brief review of several of his earlier papers on this
+     subject with additional notes.
+
+     SIMPSON, W.J.R. Recent Discoveries Which Have Rendered Antimalarial
+     Sanitation More Precise and Less Costly. _Brit. Med. Jour._, 1907,
+     II, pp. 1044-46. Discussion of the various factors in mosquito
+     control.
+
+     STEPHENS, J.W.W., AND CHRISTOPHERS, S.R. The Practical Study of
+     Malaria and Other Blood Parasites. London, 1908. Chapters on
+     mosquitoes, flies and ticks and their relation to diseases.
+
+     STERNBERG, G.M. The Malarial Parasite and Other Pathogenic
+     Protozoa. _Pop. Sci. Mo._, Vol. 50, 1897, pp. 628-641. Account of
+     the discovery of the malarial parasite and more recent studies on
+     it.
+
+     STERNBERG, G.M. Malaria. _Smith. Rept._, 1900, pp. 645-656. Review
+     of the experimental evidence in support of the mosquito-malaria
+     theory.
+
+     Malarial Fever. _Jour. Trop. Med. & Hyg._, II, Mar. 16, 1908, pp.
+     96-98. A list of literature mostly for the years 1906 and 1907.
+
+
+YELLOW FEVER
+
+     ADAMS, S.H. Yellow Fever, a Problem Solved. The battle of New
+     Orleans against the mosquito. _McClure's Magazine_, Vol. 27, June,
+     1906, p. 178. An interesting popular article.
+
+     CARROLL, JAMES. Yellow Fever. _Osler's Mod. Med._, Vol. II, 1907,
+     p. 736. History, aetiology, treatment. A good review of the work of
+     the Yellow Fever Com. and the results of their work.
+
+     CARROLL, JAMES. The Transmission of Yellow Fever. _Amer. Med.
+     Assn._, 40, 1905, pp. 1429-33. Shows the relation of the mosquito
+     to the disease.
+
+     CARROLL, JAMES. Yellow Fever. Lessons to be learned from the
+     present outbreak of yellow fever. _Jour. of Amer. Med. Assn._, Vol.
+     45, 1905, pp. 1079-81. Among other things recommends that
+     mosquitoes be kept from patients.
+
+     CHAILLE, S.E. The _Stegomyia_ and Fomites. _Amer. Med. Assn._, 40,
+     1903, pp. 1433-40. Concludes that the mosquito is the only proven
+     disseminator of yellow fever. Extended discussion by various
+     physicians.
+
+     DASTRE, A. The Fight Against Yellow Fever. _Smith. Rept._, 1905,
+     pp. 339-350. History of the yellow fever epidemics, its
+     geographical distribution, and the work that is being done to
+     control it.
+
+     DOTY, A.H. On the Mode of Transmission of the Infectious Agent in
+     Yellow Fever and Its Bearing upon the Quarantine Regulations. _Med.
+     Record_, Oct. 26, 1901, pp. 649-653. Review of older theories in
+     regard to the spread of yellow fever. Believes that the quarantines
+     are now unnecessary.
+
+     FINLEY, CHAS. The Mosquito Theory of the Transmission of Yellow
+     Fever and Its New Development. _Med. Record_, Jan. 19, 1901. Refers
+     to his early observations on the subject, giving extracts from some
+     of his earlier papers to show that he had long held the mosquito
+     responsible for the dissemination of yellow fever.
+
+     GOLDBERGER, JOS. Yellow Fever, AEtiology, Symptoms and Diagnosis.
+     _Yellow Fever Inst. Bull. 16, Pub. Health and Mar. Hospt. Ser._,
+     1907. Includes discussion of the relation of mosquitoes to the
+     disease.
+
+     GUITERAS, JOHN. Experimental Yellow Fever at the Inoculation
+     Station of the Sanitary Department of Havana. _Amer. Med._, Vol.
+     II, No. 21, 1901, pp. 809-817. Experiments show that all types of
+     the yellow fever from mild to severe may be produced by the bite of
+     the mosquito.
+
+     MCFARLAND, JOSEPH. Life and Work of James Carroll. Memoir read at
+     the fifth annual meeting of the Soc. of Tropical Med., 1908. Early
+     life of Carroll and his work with the Yellow Fever Com.
+
+     PARKER, H.B., BEYER, G.E., AND POTHIER, O.L. Rept. of Working Party
+     No. 1, Yellow Fever Institute. _Bull. 13, Pub. Health and Mar.
+     Hospt. Ser._, 1903. As a result of their studies they believe that
+     the disease is caused by a protozoan parasite which they name and
+     describe. Discuss the relation of mosquitoes to the disease.
+
+     REED, WALTER; CARROLL, JAMES; AND AGRAMONTE, A. Experimental Yellow
+     Fever. _Amer. Med._, July 6, 1901, pp. 15-23. Records of certain
+     experiments and their results.
+
+     REED, WALTER; CARROLL, JAMES; AND AGRAMONTE, C.A. The AEtiology of
+     Yellow Fever. A preliminary note presented at the Amer. Pub. Health
+     Assn. _Philad. Med. Jour._, Oct. 27, 1900, pp. 790-796. Also an
+     additional note in _Jour. Amer. Med. Assn._, 36, pp. 431-440, 1901.
+     Records of their experiments and a summing up of the data in regard
+     to yellow fever and the mosquito.
+
+     REED, WALTER, AND CARROLL, JAMES. The Prevention of Yellow Fever.
+     _Med. Record_, Oct. 26, 1901, pp. 441-449. History of the disease,
+     especially in U.S., results of the work of Yellow Fever Com.
+     description, life-history and habits of the mosquito, its relation
+     to yellow fever, methods of control. Important paper.
+
+     REED, WALTER. Recent Researches Concerning the AEtiology,
+     Propagation and Prevention of Yellow Fever by U.S. Army Com. _Jour.
+     Hyg._, 2, 1902, pp. 101-119. Review of work of the Yellow Fever
+     Com. and the importance of the results. Bibliography.
+
+     ROSENAN, M.J., PARKER, H.B., FRANCIS, E., AND BEYER, G.E. Rept. of
+     Working Party No. 2, Yellow Fever Institute. Experimental studies
+     in yellow fever and malaria at Vera Cruz, Mex. _U.S. Pub. Health
+     and Mar. Hospt. Ser._, May, 1904. Includes experiments and
+     observations on mosquitoes.
+
+     ROSENAN, M.J., AND GOLDBERGER, JOS. Report of Working Party No. 3,
+     Yellow Fever Institute. _Yellow Fever Inst. Bull. 15, Pub. Health
+     and Mar. Hospt. Ser._, 1906. Unsuccessful attempts to grow the
+     yellow fever parasite. Negative results in the experimental study
+     of the hereditary transmission of the yellow fever in the mosquito.
+     Appendix A gives a translation of Marchoux and Simonds' report in
+     which they report positive results in their experiments along the
+     same line.
+
+     STERNBERG, G.M. Transmission of Yellow Fever by Mosquitoes. _Smith.
+     Rept._, 1900, pp. 657-673. Review of the early theories in regard
+     to yellow fever and the work and findings of the yellow fever
+     commission.
+
+     WHITE, J.H. Yellow Fever and the Mosquito. _Jour. Amer. Med.
+     Assn._, LI, No. 26, Dec. 26, 1908. Considers both _S. calopus_ and
+     _C. pungens_. Results of early mistakes. Necessity of destroying
+     mosquito. Methods of destroying mosquito. Habits of mosquito.
+
+     Abstract of the Report of the French Yellow Fever Com. at Rio de
+     Janeiro, 1903. _Pub. Health Report, Pub. Health and Mar. Hospt.
+     Ser._, Vol. 19, Pt. I, p. 1019. A summary of their findings and
+     conclusions to the date of report.
+
+     DE YBARRA, A.M.F. Yellow Fever Again in Cuba. _Jour. Trop. Med. &
+     Hyg._, XI, Mar. 2, 1908, pp. 73-78. Cites a number of cases of
+     yellow fever within the last few years and uses them as evidence
+     to show that the disease may be transmitted in other ways than by
+     the mosquito. A strong summing up of the arguments against the
+     mosquito theory. Reprint of editorial in _Tex. Med. Jour._, Oct.,
+     1907, also follows this article.
+
+     The Extinction of Yellow Fever at Rio de Janeiro. _Lancet_, II,
+     1909, p. 404. A review of a French publication giving the results
+     of the work from 1903 to present time. In 1903 before work was
+     begun there were 584 deaths from yellow fever. In 1908 only 4, and
+     none so far in 1909. Success accredited to mosquito work and
+     general sanitation.
+
+     A Pioneer in Research on Yellow Fever. Editorial in _Brit. Med.
+     Jour._, May 30, 1908, p. 1306. Refers to the work of L.D.
+     Beauperthuy, who, in 1853, set forth the theory that yellow fever
+     was transmitted by mosquitoes.
+
+
+DENGUE
+
+     ASHBURN, P.M., AND CRAIG, C.F. Experimental Investigations
+     Regarding the AEtiology of Dengue Fever. _Jour. Infec. Diseases_,
+     Vol. V, 1907, pp. 440-475. Conclude that the disease is spread only
+     by mosquitoes.
+
+     COLEMAN, THOMAS D. Dengue. _Osler's Mod. Med._, Vol. II, 1907, p.
+     489. AEtiology, pathology, etc.; possibility of _Culex fatigans_
+     disseminating the disease.
+
+     GRAHAM, H. "The Dengue"; a Study of Its Pathology and Mode of
+     Propagation. _Jour. of Trop. Med. & Hyg._, July 1, 1903, p. 209.
+     Experiments which seem to show that dengue is transmitted by _Culex
+     fatigans_.
+
+     LEICHTENSTERN, O. Dengue. In Nothnagel's _Encyclopedia of Practical
+     Med._, Amer. Ed., 1905, pp. 720-743. Consideration of the disease
+     and its transmission.
+
+     ROSS, E.H. The Prevention of Dengue Fever. _Amer. Trop. Med. &
+     Parasit._, Vol. II, No. 3, July 1, 1908, pp. 193-195. A successful
+     campaign against the mosquitoes in Port Said in 1906 stopped the
+     outbreaks of malaria and dengue.
+
+     Dengue and Sand-flies. _Jour. Trop. Med. & Hyg._, 12, 1909, pp.
+     172-173. A note on these pages refers to the work of Dr. R. Doerr,
+     who suspects that dengue may be carried by sand-flies,
+     _Phlobotomus_, as well as by mosquitoes.
+
+
+FILARIAL DISEASES AND ELEPHANTIASIS
+
+     CHRISTOPHERS, S.R. What Is Really Known of the Cause of
+     Elephantiasis. _Ind. Med. Gaz._, Nov., 1907, p. 404. Questions
+     Manson's theory in regard to the disease being caused by filaria.
+
+     MANSON, PATRICK. Tropical Diseases. London, 1908, pp. 594-648. A
+     most comprehensive chapter on filariasis and elephantiasis.
+
+     PHALEN, J.M., AND NICHOLS, H.J. Filariasis and Elephantiasis in
+     Southern Luzon. _Phil. Jour. Sci._, Sept., 1908. _Culex
+     microannulatus_ regarded as the carrier of the filaria.
+
+     PROUT, W.T. On the Role of Filaria in the Production of Disease.
+     _Jour. Trop. Med. & Hyg._, Apr. 1, 1908, p. 109. Discussion of same
+     in same journal, June 1, 1908.
+
+     WHITE, DUNCAN. Filarial Periodicity and Its Association with
+     Eosinophilia. _Jour. Trop. Med. & Hyg._, 12, July 15, 1909, pp.
+     175-183. Among other things he discusses the relation of mosquitoes
+     to filarial diseases.
+
+
+LEPROSY
+
+     BRINCKERHOFF, W.R. A Note upon the Possibility of the Mosquito
+     Acting in the Transmission of Leprosy. _Pub. Health and Mar. Hospt.
+     Ser._ (general publications), 1908. Suggests the possibilities of
+     such transmission, but concludes that the probabilities are against
+     it.
+
+     GOODHUE, E.S. The Bacillus Leprae in the Gnat and Bedbug. _Ind.
+     Med. Gaz._, Vol. XLI, Aug., 1906, p. 342. Has found this bacillus
+     in mosquitoes and bedbugs, but believes the latter is more
+     concerned in transmitting the disease.
+
+     GOODHUE, E.S. Mosquitoes and Their Relation to Leprosy in Hawaii.
+     _Amer. Med._, N.S., 2, 1907, p. 593. Suggests that mosquitoes may
+     carry the disease, also warns against danger from flies and
+     bedbugs.
+
+     HUTCHINSON, J. Mosquitoes and Leprosy. _Brit. Med. Jour._, Dec. 22,
+     1906, Vol. II, p. 1841. Evidence against the insect theory of
+     transmission of leprosy.
+
+     MUGLISTON, T.C. On a Possible Mode of Communication of Leprosy.
+     _Jour. Trop. Med._, Vol. VIII, July 15, 1905, p. 209. Suggests that
+     the itch-mite may be the carrier of leprosy. Studies on 77 lepers
+     led him to this conclusion.
+
+     SMYTH, W.R. Leprosy. _Brit. Med. Jour._, Dec. 8, 1906, Vol. II, p.
+     1670. Believes that bedbugs or some similar wingless parasite
+     conveys the disease.
+
+
+PLAGUE
+
+     BRANNERMAN, W.B. Spread of Plague in India. _Jour. of Hyg._, Vol.
+     6, No. 2, Apr., 1906, pp. 179-211. A digest of experiments made in
+     India. Discusses various ways in which the disease may be spread.
+     Review of the evidence that insects may be concerned. Bibliography.
+
+     CALVERT, W.J. Plague. _Osler's Mod. Med._, Vol. II, 1907, p. 760.
+     History; bacteriology; pathology; plague among animals;
+     transmission, etc.
+
+     HAM, B. BURNETT. Report on Plague in Queensland, 1900-1907. P. 153
+     discusses the rat-flea theory of dissemination of bubonic plague,
+     summing up the evidence of various observers, including the Indian
+     Advisory Com. and others. Considers the evidence conclusive that
+     _P. cheopis_ and possibly _C. fasciatus_ transmit plague. Other
+     pages discuss various rat fleas and their relation to plague in
+     rats.
+
+     HANKIN, E.H. On the Epidemiology of Plague. _Jour. Hyg._, 5, 1905,
+     pp. 48-83. A comprehensive discussion of the disease and its
+     spread, several pages devoted to rats and fleas; evidence for and
+     against the theory that rats and fleas are the principal carriers
+     of the disease.
+
+     HERZOG, MAX. The Plague, Bacteriology, Morbid Anatomy &
+     Histopathology, Including the Consideration of Insects as Plague
+     Carriers. Biological Laboratory Bureau of Govt. Laboratories,
+     Manila, Oct., 1904. Reviews the evidence regarding the possibility
+     of fleas carrying plague; describes a new rat flea (_Pulex
+     philippinensis_); records experiments with fleas and cites a case
+     of bubonic plague in a child in which the infection was possibly
+     carried by _Pediculi_.
+
+     MCCOY, G.W. Plague Bacilli in Ectoparasites of Squirrels. _Pub.
+     Health Reports, Pub. Health and Mar. Hospt. Ser._, Vol. XXIV, No.
+     16, Apr. 16, 1909. Experiments with fleas and lice from infected
+     squirrels demonstrating presence of plague bacilli.
+
+     MCCOY, G.W. The Susceptibility of Gophers, Field-mice and
+     Ground-squirrels to Plague Infection. _Jour. of Infec. Diseases_,
+     Vol. 6, 1909, No. 3, pp. 283-288. Gophers highly resistant,
+     field-mice moderately susceptible and ground-squirrels very
+     susceptible to plague.
+
+     MITZMAIN, M.B. Insect Transmission of Bubonic Plague: a Study of
+     the San Francisco Epidemic. _Ento. News_, 19, No. 8, 1908, pp.
+     353-359. Fleas obtained in examination of 1,800 rats. Attempt to
+     locate source of rat and flea introduction.
+
+     MORTON, F.M. Eradicating Plague from San Francisco. Report of the
+     Citizens' Health Com. and an account of its work. San Francisco,
+     1909. Discusses the epidemics, methods of transmission, methods of
+     fighting, etc.
+
+     RUCKER, W.C. Plague Among Ground-squirrels in Contra Costa Co.,
+     Cal. _Pub. Health Reports, Pub. Health and Mar. Hospt. Ser._, Aug.
+     27, 1909. Reports of human cases supposed to be connected with
+     plague among ground-squirrels. Plague among squirrels; habits,
+     methods of fighting, etc.
+
+     RUCKER, W.C. Fighting an Unseen Foe. _Sunset Mag._, XXII, No. 2,
+     Feb., 1909. Story of the fight against plague in San Francisco.
+
+     SHIPLEY, A.E. Rats and Their Animal Parasites. _Jour. Eco.
+     Biology_, Vol. III, No. 3, Oct. 28, 1908. List of species of ecto-
+     and endoparasites.
+
+     SIMPSON, W.J. A Treatise on Plague. Cambridge Univ. Press, London,
+     1906. Deals with historical, epidemiological, clinical, therapeutic
+     and preventive aspect of the disease.
+
+     THOMPSON, J.A. The Mode of Spread and Prevention of Plague in
+     Australia. _Lancet_, Oct. 19, 1907, p. 1104. Rat fleas the
+     essential factor in transmitting plague, and preventive methods
+     should be directed against the rats.
+
+     THOMPSON, J.A. On the Epidemiology of Plague. _Jour. Hyg._, Vol.
+     VI, No. 5, Oct., 1906. Methods of infection, spread, relation of
+     rats to the disease and a review of the rat-flea theory.
+     Bibliography.
+
+     VERJBITSKI, D.T. The Part Played by Insects in the Epidemiology of
+     Plague. _Jour. Hyg._, 8, 1908, No. 2, pp. 162-208. Record of
+     extensive experiments with fleas. Fleas communicated plague for
+     three days, bedbugs for five days. Interrelation of fleas, rats,
+     dogs, cats, and man. An important article translated from Russian.
+
+     WHERRY, W.B. Further Notes on the Rat Leprosy and on the Fate of
+     the Human and Rat Leper Bacillus in Flies. _Jour. Infec. Diseases_,
+     Vol. 5, No. 5, 1908. Discussion and references, experiments with
+     flies, summary, etc. More than 1,115 lepra-like bacilli were
+     counted in a single fly-speck.
+
+     WHERRY, W.B. Plague Among the Ground-squirrels of California.
+     _Jour. Infec. Diseases_, Vol. 5, No. 5, 1908, pp. 485-533. How the
+     plague was first discovered among rats, records of cases and a
+     discussion of the possible relation of this to human plague cases.
+
+     Eradicating Plague in San Francisco; Report of the Citizens' Health
+     Committee, 1909. An account of the recent outbreaks and the methods
+     of fighting them.
+
+     Report of the Indian Plague Commission, Vol. V, pp. 75-77, 1901. In
+     these pages the Commission considers the question of the
+     transference of plague by suctorial insects. It considers Simonds'
+     claims and others and believes that "suctorial insects do not come
+     under consideration with the spread of plague."
+
+     Reports on Plague Investigations in India Issued by the Advisory
+     Committee Appointed by the Sec. of State for India, the Royal
+     Society and the Lister Institute. The reports include the reports
+     of the Working Commission appointed by the Advisory Committee and
+     reports on various contributory investigations. They are published
+     in the _Jour. of Hygiene_ as "Extra Plague Numbers." All these
+     reports deal very largely with the relation of the rat and flea to
+     plague, and are commonly referred to as "Reports of Indian Plague
+     Commission." The first number, Vol. VI, Sept., 1906, contains
+     articles on "Experiments upon the Transmission of Plague by Fleas."
+     "Note on the Species of Fleas Found on Rats, _Mus rattus_ and _Mus
+     decumanus_ in Different Parts of the World." "The Physiological
+     Anatomy of the Mouth-parts and Alimentary Canal of the Indian Rat
+     Flea, _Pulex cheopis_," and other papers on the relation of rats to
+     plague. The second number, Vol. VII, July, 1907, contains articles
+     on "On the Significance of the Locality of the Primary Bubo in
+     Animals Infected with Plague in Nature," "Further Observations on
+     the Transmission of Plague by Fleas with Special Reference to the
+     Fate of Plague Bacillus in the Body of the Rat Flea,"
+     "Experimental Production of Plague Epidemics Among Animals,"
+     "Experiments in Plague Houses in Bombay," "On the External Anatomy
+     of the Indian Rat Flea and Its Differentiation from Some Other
+     Common Fleas," "A Note on Man as a Host of the Indian Rat Flea,"
+     and others on the relation of rats to plague. The third number,
+     Vol. VII, Dec., 1907, contains articles on "Digest of Recent
+     Observations on the Epidemiology of Plague" (Bibliography),
+     "Epidemiological Observations in Bombay City," "Epidemiological
+     Observations in the Villages of Wadhala, Parel, Worli in the
+     Neighborhood of Bombay Village," "General Considerations Regarding
+     the Spread of Infection, Infectivity of Houses, etc., in Bombay
+     City and Island," "Epidemiological Observations in the villages of
+     Dhand and Kasel (Punjab)." The fourth number, Vol. VIII, May, 1908,
+     contains articles on "The Part Played by Insects in the
+     Epidemiology of Plague" (see also ref. under D.T. Verjbitski),
+     "Observations on the Bionomics of Fleas with Special Reference to
+     _P. cheopis_," "The Mechanism by Means of Which the Flea Cleans
+     Itself of Plague Bacilli," "On the Seasonal Prevalence of Plague in
+     India."
+
+     See also under Fleas.
+
+
+FLEAS
+
+     BAKER, C.F. Fleas and Disease. _Science_, N.S., Vol. 22, No. 559,
+     Sept. 15, 1905, p. 340. Discusses the possibility of fleas
+     transmitting leprosy.
+
+     DOANE, R.W. Notes on Fleas, Collected on Rat and Human Hosts in San
+     Francisco and Elsewhere. _Can. Ento._, 40, 1908, pp. 303-304. Shows
+     that _Ceratophyllus fasciatus_ and _Pulex irritans_ are common on
+     both man and rats.
+
+     FOX, CARROLL. The Flea in Its Relation to Plague, with a Synopsis
+     of the Rat Fleas. _The Military Surgeon_, 24, June, 1909, pp.
+     528-537. Review of the work of the Indian Plague Commission and
+     others. Key for identification of rat fleas.
+
+     GALLI-VALERIO. The Part Played by Fleas of Rats and Mice in the
+     Transmission of Bubonic Plague. _Jour. Trop. Med._, Feb., 1902.
+     Attacks the theory that plague can be conveyed from rats to men by
+     fleas because rat fleas do not bite men.
+
+     MCCOY, G.W. _Siphonaptera_ Observed in the Plague Campaign in
+     California with a Note upon Host Transference. _Pub. Health Report,
+     Pub. Health and Mar. Hospt. Ser._, Vol. XXIV, No. 29, July 16,
+     1909. Lists of species from various hosts. Report on experiments in
+     transferring rat fleas to squirrels and squirrel fleas to rats.
+
+     MCCOY, G.W., AND MITZMAIN, M.B. An Experimental Investigation of
+     the Biting of Man by Fleas Taken from Rats and Squirrels. _Public
+     Health Report_, XXIV, No. 8, Feb. 19, 1909, pp. 189-194. Rat and
+     squirrel fleas will bite man.
+
+     MITZMAIN, M.B. Insect Transmission of Bubonic Plague. A Study of
+     the San Francisco Epidemic. _Entomological News_, Oct., 1908.
+     Source and distribution of species of fleas and brief notes on work
+     of Indian Plague Commission.
+
+     MITZMAIN, M.B. How a Hungry Flea Feeds. _Entomological News_, Dec.,
+     1908.
+
+     MITZMAIN, M.B. Some New Facts on the Bionomics of the California
+     Rodent Fleas. _Annals Ento. Soc. Amer._, III, pp. 61-82, 1910.
+
+     SHIPLEY, A.E. Rats and Their Animal Parasites. _Jour. of Economic
+     Biology_, Vol. 3, No. 3, Oct. 28, 1908. List of species ecto- and
+     endoparasites.
+
+     See also reports of Advisory Commission under Plague.
+
+
+TYPHOID FEVER
+
+     ANDERSON, J.F. The Differentiation of Outbreaks of Typhoid Fever
+     Due to Water, Milk, Flies and Contact. _Amer. Jour. Pub. Health_,
+     19, pp. 251-259. Discusses flies and typhoid.
+
+     MCCRAE, THOMAS. Typhoid Fever. _Osler's Mod. Med._, Vol. II, p.
+     70, 1907. A full discussion of this disease.
+
+     REED, WALTER; VAUGHAN, V.C., AND SHAKESPEARE, E.O. Abstract of
+     Report on the Origin and Spread of Typhoid Fever in the U.S.
+     Military Camps During the Spanish War of 1898. Washington, Govt.
+     Printing Office, 1900. Shows among other things that "flies
+     undoubtedly served as carriers of infection."
+
+     ROSEMAN, M.J., LUMSDEN, L.L., AND KASTLE, J.H. Report on Origin and
+     Prevalence of Typhoid Fever in D.C. Including reports by Stiles,
+     Goldberger and Stimson. _Bull. 35 of Hygienic Laboratory of U.S.
+     Public Health and Mar. Hospt. Ser._, 1907. (Second report in _Bull.
+     44_, 1907, includes nothing about insects.)
+
+     VEEDER, M.A. Typhoid Fever from Sources Other Than Water Supply.
+     _Med. Record_, 62, pp. 121-124, July 26, 1902. Cites several
+     instances where flies might act as the carriers of the disease.
+
+     WHIPPLE, GEO. C. Typhoid Fever, Its Causation, Transmission and
+     Prevention. N.Y., 1908. Considers that house-flies and probably
+     fruit-flies carry typhoid bacilli.
+
+
+HOUSE-FLIES; ANATOMY, LIFE-HISTORY, HABITS
+
+     FELT, E.P. Observations on the House-fly. _Jour. Eco. Ento._, III,
+     No. 1, Feb., 1910, pp. 24-26. Shows that it does not breed freely
+     in darkness.
+
+     GRIFFITH, A. The Life-history of House-flies. _Public Health_
+     (London), 21, No. 3, 1908, pp. 122-127. Study of life-history.
+     Flies require water frequently, eggs hatch in twenty-four hours,
+     larval stage four days. Each female may lay four batches of eggs.
+     Destroy manure and rubbish.
+
+     HAMER, W.H. The Breeding of Flies Summarized. _Am. Med._, 3, 1908,
+     p. 431. Habits of flies and experiments to show that they may carry
+     the germs of various diseases.
+
+     HEPWORTH, JOHN. On the Structure of the Foot of the Fly. _Quar.
+     Jour. Micro. Sci._, II, 1859, pp. 158-563. One plate showing feet
+     of different flies. A review of the older theories of how a fly was
+     able to walk on smooth surfaces.
+
+     HERMS, W.B. The Essentials of House-fly Control. _Bull. of Berkeley
+     Board of Health_, Berkeley, Cal., 1909. Recommends removing manure
+     as soon as possible and keeping it in tight bins until removed. No
+     very satisfactory insecticides have been found for use in treating
+     manure piles.
+
+     HERMS, W.B. The Berkeley House-fly Campaign. _Cal. Jour. of
+     Technology_, Vol. XIV, No. 2, 1909. Discusses the methods that have
+     been used in fighting the fly in Berkeley, Cal. Removing manure
+     regularly or keeping it in closed bins recommended.
+
+     HEWITT, C.G. A Preliminary Account of the Life-history of the
+     Common House-fly. _Mem. and Proc. Manchester Lit. Phil. Soc._,
+     1906, Vol. 51, pp. 1-4.
+
+     HEWITT, C.G. On the Bionomics of Certain Calyptrate Mucidae and
+     Their Economic Significance with Especial Reference to Flies
+     Inhabiting Houses. _Jour. Econ. Biol._, 1907, Vol. II, pp. 79-88.
+     Character and importance of group and notes on many species.
+
+     HEWITT, C.G. Structure, Development and Bionomics of the House-fly,
+     _Muca domestica_. Part I, _Quar. Jour. Micro. Sci._, 1907, p. 395,
+     on anatomy, external and internal, and bibliography. Part II, same;
+     1908, p. 495. Breeding-habits, development and anatomy of larvae,
+     bibliography. Part III, same; 1909, pp. 347-414. The bionomics,
+     allies, parasites, and the relations to human disease. The best
+     article on the house-fly.
+
+     HOWARD, L.O. Further Notes on the House-fly. _Bull. 10, U.S. Dept.,
+     Agric. Div. of Ento._, p. 63, 1898. Experiments to kill larvae in
+     manure.
+
+     HOWARD, L.O. House-flies. _U.S. Dept. of Agric., Bureau of Ento.,
+     Circular No. 71_, revised ed., 1906. Methods of control of
+     house-fly and related species.
+
+     HOWARD, L.O., AND MARLATT, C.L. _Bull. 4, U.S. Dept. Agric., Div.
+     of Ento._, pp. 43-47, 1896. General account with methods of
+     controlling.
+
+     JEPSON, F.P. The Breeding of the Common House-fly During the Winter
+     Months. _Jour. Econ. Biol._, 4, 1909, pp. 78-82. Records of certain
+     experiments which show that the flies will breed in winter under
+     favorable conditions.
+
+     NEWSTEAD, R. Preliminary Report on the Habits, Life-cycle and
+     Breeding-places of the Common House-fly as Observed in the City of
+     Liverpool, with Suggestions as to the Best Means of Checking Its
+     Increase. Liverpool, Oct. 3, 1907.
+
+     NEWSTEAD, R. On the Habits, Life-cycle and Breeding-places of the
+     Common House-fly. _Ann. Trap. Med. Para._, Vol. I, No. 4, Feb. 29,
+     1908, pp. 507-520. Final report on this subject. Sums up notes on
+     life-history, habits, breeding-places, etc. Important article.
+
+     PACKARD, A.S. On the Transformation of the Common House-fly with
+     Notes on Allied Forms. _Proc. Boston Soc. Nat. Hist._, Vol. XVI,
+     1874, pp. 136-140. Life-history and anatomy.
+
+     WILCOX, E.V. Fighting the House-fly. _Country Life in America_,
+     May, 1908. Methods of controlling this pest.
+
+
+HOUSE-FLIES AND TYPHOID
+
+     AUSTEN, E.E. The House-fly and Certain Allied Species as
+     Disseminators of Enteric Fever Among the Troops in the Field.
+     _Jour. Roy. Army Med. Corps_, June, 1904. Suggests that it may
+     carry enteric fever and other diseases; method of control.
+
+     FELT, E.P. The Typhoid or House-fly and Disease. In 24th _Rept. of
+     State Ento_. in _N.Y. State Museum Bull._, No. 455, 1909. A general
+     discussion with complete bibliography.
+
+     FIRTH, R.H., AND HORROCKS, W.H. An Inquiry Into the Influence of
+     Soil, Fabrics, and Flies in the Dissemination of Enteric Infection.
+     _Brit. Med. Jour._, Vol. II, 1902, pp. 936-942. House-flies carry
+     enteric bacilli. They may pass through digestive tract and remain
+     virulent.
+
+     HAMILTON, ALICE. The Fly as a Carrier of Typhoid. _Jour. Amer. Med.
+     Assn._, 40, 1903, pp. 576-83. A study of a typhoid outbreak in
+     Chicago gives good evidence that the flies were important factors
+     in the spread of the disease.
+
+     HEWITT, C.G. The Biology of House-flies in Relation to Public
+     Health. _Royal Inst. Pub. Health Jour._, Oct., 1908.
+
+     HOWARD, L.O. A contribution to the Study of the Insect Fauna of
+     Human Excrement. _Proc. Wash. Acad. Sci._, 2, 1900, pp. 541-600.
+     Special reference to the house-fly and typhoid fever.
+
+     HOWARD, L.O. Flies and Typhoid. _Pop. Sci. Mo._, Jan., 1901, pp.
+     249-256. A popular account of several species of flies that may be
+     concerned in carrying typhoid.
+
+     KLEIN, E. Flies as Carriers of _B. typhus_. _Brit. Med. Jour._,
+     Oct. 17, 1908, pp. 1150-51. In cultures made from flies he found
+     great numbers of _B. coli communis_ and _B. typhosus_, showing that
+     flies may carry these germs.
+
+     MARTIN, A. Flies in Relation to Typhoid and Summer Diarrhea.
+     _Public Health_, 15, 1903, pp. 652-653. Believes that the house-fly
+     is largely responsible for these diseases.
+
+     REED, WALTER. _War Dept. An. Rept._, 1899, pp. 627-633. Flies the
+     cause of a typhoid outbreak in army in 1899.
+
+
+HOUSE-FLY AND VARIOUS DISEASES
+
+     BUCHANAN, R.A., GLASG, F.F., AND M.B. The Carriage of Infection by
+     Flies. _Lancet_, 173, 1907, pp. 216-218. Flies carry various germs
+     on their feet and distribute them where they walk. Must protect
+     food from contamination.
+
+     BREWSTER, E.T. The Fly. The Disease of the House. _McClure's
+     Magazine_, XXXIII; No. 5, Sept., 1909, pp. 564-568. Proposes to
+     make use of tropisms for ridding the houses of flies.
+
+     CASTELLANI, ALDO. Experimental Investigation on _Framboesia
+     tropica_ (Yaws). _Jour. of Hyg._, Vol. VII, 1907, pp. 558-599. On
+     pages 566-568 he discusses the part played by insects in
+     transmitting the disease. Gives detail of experiments conducted and
+     concludes that under certain conditions yaws may be conveyed by
+     flies and possibly other insects.
+
+     COBB, J.O. Is the Common House-fly a Factor in the Spread of
+     Tuberculosis? _Amer. Med._, 9, 1905, pp. 475-477. Believes that the
+     bacilli may enter the system through the digestive tract and that
+     flies carry them to our food.
+
+     DICKENSON, G.K. The House-fly and Its Connection with Disease
+     Dissemination. _Med. Record_, 71, 1907, pp. 134-139. Summary;
+     bibliography.
+
+     ESTEN, W.M., AND MASON, C.J. Sources of Bacteria in Milk. Starr's
+     _Agric. Ex. Stn., Conn. Bull._, 51, 1908. Shows how flies may carry
+     bacteria to milk. Table showing number of bacteria on flies from
+     various sources.
+
+     FELT, E.P. The Economic Status of the House-fly. _Jour. Eco.
+     Ento._, Vol. 2, No. 1, Feb., 1909, pp. 39-45. A summary of the
+     charges, possibilities, proofs, etc. Discussion.
+
+     GUDGER, E.W. Early Note on Flies as Transmitters of Disease.
+     _Science_, N.S. Vol. 31, Jan. 7, 1910, pp. 31-32.
+
+     HAMER, W.H. Nuisance from Flies. _London County Council Rept._ No.
+     1,138, pp. 1-10, and No. 1,207, pp. 1-6, 1908. Observations on
+     various flies and their relation to diseases.
+
+     HAYWARD, E.H. The Fly as a Carrier of Tuberculosis Infection. _N.Y.
+     Med. Jour._, 80, 1904, pp. 643-644. Tubercular bacilli pass through
+     the digestive tract of flies and remain virulent.
+
+     HOWARD, L.O. The Carriage of Disease by Flies. _Bull. 30_, N.S.,
+     pp. 39-45, _U.S. Dept. Agric, Div. of Ento._, 1901. Discussion of
+     flies as carriers of disease.
+
+     HOWARD, L.O. House-flies. _U.S. Dept. of Agric., Bureau of Ento._,
+     Cir. No. 71, revised ed., Sept. 21, 1906. Notes on the various
+     species visiting houses; habits; methods of control; regulations
+     for controlling flies in cities.
+
+     HUTCHINSON, WOODS. The Story of the Fly That Does Not Wipe Its
+     Feet. _Sat. Evening Post_, March 7, 1908.
+
+     JACKSON, DANIEL D. Conveyance of Disease by Flies Summarized.
+     _Bost. Med. & Surg. Jour._, 1908, p. 451. Disease and flies prevail
+     at same time; records over 1,000,000 bacteria to each fly caught on
+     swill-barrels.
+
+     JACKSON, DANIEL B. Pollution of New York Harbor as a Menace to
+     Health by the Dissemination of Intestinal Diseases Through the
+     Agency of the Common House-fly. Account of experiments and
+     deductions. Pamphlet issued July, 1908, by Merchants' Assn. of New
+     York.
+
+     LEIDY, JOSEPH. Flies as a Means of Communicating Contagious
+     Diseases. _Proc. Acad. Nat. Sci. Phil._, 23, 1871, p. 297. Believes
+     that flies may carry disease; refers to flies in connection with
+     gangrene and wounds.
+
+     LORD, F.T. Flies and Tuberculosis. _Bost. Med. & Surg. Jour._,
+     1904, pp. 651-654. Fly-specks may contain virulent tubercular
+     bacilli for at least fifteen days.
+
+     MAYS, THOS. J. The Fly and Tuberculosis. _N.Y. Med. Jour. & Phila.
+     Med. Jour._, 82, 1905, pp. 437-438. Believes that J.O. Cobb's data
+     as given in _Amer. Med. Jour._ is not at all conclusive.
+
+     NASH, J.C.T. A Note on the Bacterial Contamination of Milk as
+     Illustrating the Connection Between Flies and Epidemic Diarrhea.
+     _Lancet_, II, 1908, pp. 1668-69. Experiments show that milk left
+     exposed to flies soon contains many more germs than that protected
+     from them.
+
+     NASH, J.C.T. The AEtiology of Summer Diarrhea. _Lancet_, 164, 1903,
+     p. 330. Believes house-fly carries this disease because the two
+     appear and disappear together.
+
+     ROBERTSON, A. Flies as Carriers of Contagion in Yaws. _Jour. Trop.
+     Med. & Hyg._, 11, 1908, No. 14, p. 213. As a result of examinations
+     the author concludes that the house-fly is capable of carrying the
+     virus of yaws.
+
+     SANDILANDS, J.E. Epidemic Diarrhea and the Bacterial Control of
+     Food. _Jour. Hyg._, 6, 1906, pp. 77-92. Believes that house-flies
+     convey these diseases from the excrement of infected infants.
+
+     SIBTHORPE, E.H. Cholera and Flies. _Brit. Med. Jour._, Sept., 1896,
+     p. 700. Flies considered scavengers, think they thus help abate the
+     disease.
+
+     SMITH, T. The House-fly as an Agent in Dissemination of Infectious
+     Diseases. _Amer. Jour. Pub. Hyg._, Aug., 1908, pp. 312-317. Points
+     out that flies on account of their habits, are dangerous sources of
+     contamination.
+
+     SMITH, THEOBALD. The House-fly at the Bar. Merchants' Assn., New
+     York, 1909, pp. 1-48. Letters from various authorities giving their
+     opinion; quotations from various authors. Bibliography.
+
+     VEEDER, M.A. Flies as Spreaders of Sickness in Camps. _Med.
+     Record_, 54, 1898, pp. 429-430. Flies feed on typhoid excreta and
+     pass to food. Cultures made from fly tracks and excreta show many
+     bacteria present.
+
+     VEEDER, M.A. The Relative Importance of Flies and Water Supply in
+     Spreading Disease. _Med. Record_, 55, 1899, pp. 10-12. Reasons for
+     believing that flies spread disease in many instances. Burial of
+     infected typhoid material no protection but a menace.
+
+     Dangers from Flies. E.P.W. _Nature_, Vol. 29, pp. 482-483. Review
+     of an article by Dr. B. Grassi in regard to flies and various
+     diseases. Opthalmia is discussed. Flies may ingest and pass
+     unharmed eggs of various human parasites including tapeworm.
+
+
+HUMAN MYIASIS
+
+     ALLEN, CHAS. H. Demonstration of Locomotion in the Larvae of the
+     OEstridae. _Proc. Amer. Assn. Adv. Set._, Vol. 24, 1875, pp.
+     230-236. Larvae taken from flesh of child, one had moved thirty-six
+     inches and one six inches.
+
+     FRENCH, G.H. A Parasite the Supposed Cause of Some Cases of
+     Epilepsy. _Canad. Ento._, 32, 1900, pp. 263-264. Larvae of
+     _Gastrophilus_ or _Dermatobia_ in the alimentary canal supposed to
+     have caused spasms in young boy.
+
+     GILBERT, N.C. Infection of Man by Dipterous Larvae with Report of
+     Four Cases. _Archives of Internal Med._, Oct., 1908. Historical;
+     various kinds sometimes found in man; good summary of subject.
+     Bibliography.
+
+     HARRISON, J.H.H. A Case of Myiasis. _Jour. Trop. Med. & Hyg._, XI,
+     Oct. 15, 1908, p. 305. Over 300 larvae of _Lucilia macellaria_
+     removed from face of negro woman.
+
+     HUMBERT, FRED. _Lucilia macellaria_ Infesting Man. _Proc. U.S. Nat.
+     Museum_, 6, 1883, pp. 103-104. Records several cases in which the
+     screw-worm infested patients.
+
+     JENYUS, LEONARD. _Trans. Ento. Soc._, London, Vol. II, 1839, pp.
+     152-159. Notice of a case in which the larvae of a dipterous insect,
+     supposed to be _Anthomyia canicularis_, Meig., were expelled in
+     large quantities from the human intestines.
+
+     KANE, E.R. A Grub Supposed to Have Traveled in the Human Body.
+     _Insect Life_, II, 1890, pp. 238-239. Larva of bot-fly taken from
+     face of boy. It had been traveling under the skin for about five
+     months.
+
+     MCCAMPBELL, E.F., AND COOPER, H.J. _Myiasis intestinalis_ Due to
+     Infection with Three Species of Dipterous Larvae. _Jour. Amer. Med.
+     Assn._, 53, Oct. 9, 1909, pp. 1160-62. General notes on this
+     subject and a report on a case in which larvae of three different
+     species of flies were obtained from one patient.
+
+     MEINERT, FR. _Lucilia nobilis_ Parasitic on Man. _Insect Life_, II,
+     1892, pp. 36-37. Two larvae from the ear of a man proved to be the
+     above species.
+
+     MURTFELEDT, M.E. Hominivorous Habits of the Screw-worm in St.
+     Louis. _Insect Life_, IV, 1891, p. 200. Many larvae of this species
+     removed from the nasal passages of a patient.
+
+     NELSON, J.B. Insects in the Human Ear. _Insect Life_, VI, 1893, p.
+     56. Two cases in which blow-fly larvae are reported as coming from
+     the human ear.
+
+     RILEY, W.A. A Case of Pseudoparasitism by Dipterous Larvae. _Canad.
+     Ento._, 38, 1906, p. 413. Several larvae, species undetermined,
+     removed from back of patient.
+
+     SAY, THOMAS. On a South American Species of OEstrus Which
+     Inhabits the Human Body. _Tr. Phil. Acad. Nat. Sci._, Vol. 2, 1822,
+     pp. 353-360. Extended notes on various dipterous larvae infesting
+     man.
+
+     SNOW, F.H. Hominivorous Habits of _Lucilia macellaria_ "The
+     Screw-worm." _Psyche_, 4, 1883, pp. 27-30. Cites observations made
+     by himself and others.
+
+     WILLISTON, S.W. The Screw-worm Fly _Compsomyia macellaria_.
+     _Psyche_, 4, 1883, pp. 112-114. Notes on this species with a
+     translation of a Spanish article by Anibalzaga in which instances
+     of this fly infesting human beings are recorded.
+
+     YOUNT, C.E., AND SUDLER, M.T. Human Myiasis from the Screw-worm
+     Fly. _Jour. Amer. Med. Assn._, Vol. 49, No. 23, 1907, p. 1912.
+     Several cases giving reference to literature, symptomatology,
+     diagnosis.
+
+
+STOMOXYS AND OTHER FLIES
+
+     AUSTEN, E.E. Blood-sucking and Other Flies Known or Likely to Be
+     Concerned in the Spread of Disease. In Albutt's and Rolleston's
+     _System of Med._, 2, 1907, pp. 169-186. A descriptive list of these
+     flies. Bibliography.
+
+     AUSTEN, E.E. Illustrations of African Blood-sucking Flies Other
+     Than Mosquitoes and Tsetse-flies. London, 1909.
+
+     NEWSTEAD, R. On the Life-history of _Stomoxys calcitrans_. _Jour.
+     Econom. Biology_, Vol. I, 1906, pp. 157-166. Describes habits and
+     life-history of larvae and adults. Important article.
+
+     STEPHENS, J.W.W., AND NEWSTEAD, R. The Anatomy of the Proboscis of
+     Biting Flies. Part II, _Stomoxys_. _Ann. of Trop. Med. & Parasit._,
+     Vol. I, No. 2, June 15, 1907, pp. 171-182. Good anatomical paper.
+     Part I (_Glossina_) was published in mem. XVIII, 1906, Liverpool
+     School Trop. Med.
+
+     TULLOCK, F. Internal Anatomy of _Stomoxys_. _Proc. Roy. Soc._,
+     London, 77, Series B, 1906, pp. 523-531. Descriptions and drawings
+     comparing with _Glossina_.
+
+
+TSETSE-FLIES
+
+     AUSTEN, E.E. A Monograph of the Tsetse-flies. Published by order of
+     the Trustees of the British Museum, 1903.
+
+     MANSON, P. Tsetse-flies. In _Trop. Diseases_, p. 174. Description
+     of genus; table of species; distribution; reproduction, habits.
+
+     MINCHIN, E.A. Report of Anatomy of the Tsetse-fly (_Glossina
+     palpalis_). _Proc. Roy. Soc._, London, 76, Series B, 1905, pp.
+     531-547. Good account of internal anatomy of this fly, important
+     because of its relation to trypanosomiasis.
+
+     MINCHIN, E.A. The Breeding-habits of the Tsetse-fly. _Nature_, Oct.
+     25, 1906, p. 636.
+
+     MINCHIN, E.A., GRAY, A.C.H., AND TULLOCK, F.M.G. (Sleeping Sickness
+     Com.) _Glossina palpalis_ in Its Relation to _Trypanosoma
+     gambiense_ and Other Trypanosomes (Preliminary Report). _Proc. Roy.
+     Soc._, Vol. 78, 1906, pp. 242-258. Report on certain experiments in
+     feeding these flies on infected animals and in allowing supposedly
+     infected flies to feed on various animals.
+
+     NOVY, F.G. The Trypanosomes of Tsetse-flies. _Jour. Infec. Dis._,
+     III, 1906, pp. 394-411. Notes on the various species.
+
+
+TRYPANOSOMES AND TRYPANOSOMIASIS
+
+     BRUCE, DAVID. Trypanosomiasis. _Osler's Mod. Med._, Vol. I, 1907,
+     p. 460. A discussion of _Trypanosoma lewisi_, _evansi_, _brucei_,
+     _gambiensi_, and the diseases caused by them.
+
+     DUTTON, J.E., TODD, J.L., AND HARRINGTON, J.W.B. Trypanosome
+     Transmission Experiments. _Am. Trop. Med. & Parasit._, Vol. I, No.
+     2, June 15, 1907, pp. 201-229. Sections on attempts to transmit
+     trypanosomes by tsetse-flies; by other blood-sucking Arthropods,
+     etc., conclude that trypanosomes may be mechanically transmitted by
+     the bite of blood-sucking Arthropods.
+
+     HOOKER, W.A. Descriptions of Certain Trypanosomes, and Review of
+     the Present Knowledge of the Role of Ticks in the Dissemination of
+     Disease. _Jour. Econ. Ento._, Vol. I, No. 1, 1908, pp. 65-76. Good
+     review, tables and literature.
+
+     MINCHIN, E.A. Investigations on the Development of Trypanosomes in
+     Tsetse-flies and Other _Diptera_. _Quart. Jour. Micro. Sci._, 1908,
+     pp. 159-260.
+
+     MUSGROVE, W.E., AND CLEGG, M.T. Trypanosomes and Trypanosomiasis,
+     with Special Reference to Surra in the Philippine Islands.
+     _Biological Lab., Bull. No. 5_, Manila, 1903. Discuss flies, fleas,
+     mosquitoes, lice and ticks as possible disseminators of the
+     disease.
+
+     NOVY, T.G., MCNEAL, M.J., AND TORRY, H.M. The Trypanosomes of
+     Mosquitoes and Other Insects. _Jour. Infec. Diseases_, IV, 1907,
+     pp. 223-276. These parasites are often found in mosquitoes and
+     other insects. Bibliography.
+
+     NUTTALL, G.H.F. The Transmission of _Trypanosoma lewisi_ by Fleas
+     and Lice. _Parasitology_, Vol. I, No. 4, Dec., 1908, pp. 296-301.
+     This rat trypanosome is transmitted by fleas and lice.
+
+     OLD, J.E.S. Contribution to the Study of Trypanosomiasis and to the
+     Geographical Distribution of Some of the Blood-sucking Insects,
+     etc. _Jour. Trop. Med. & Hyg._, 12, Jan. 15, 1909, pp. 15-22. Notes
+     on blood-sucking _Diptera_ and ticks.
+
+     ROGERS, LEONARD. The Transmission of the _Trypanosoma evansi_ by
+     House-flies and Other Experiments Pointing to the Probable Identity
+     of Surra of India and Nagana or Tsetse-fly Disease of Africa.
+     _Proc. Roy. Soc._, Vol. LXVIII, 1901, pp. 163-170.
+
+     THIMM, C.A. Bibliography of Trypanosomiasis; embracing original
+     papers published prior to April 1909, and references to works and
+     papers on tsetse-flies. London, 1909.
+
+     TODD, J.L. A Note on Recent Trypanosome Transmission Experiments.
+     _Jour. Trop. Med. & Hyg._, 12, Sept., 1909, p. 260. Show that they
+     develop in _G. palpalis_ when taken from their mammal host at the
+     proper stage of development.
+
+     WOODCOCK, H.M. The Haemoflagellates: a Review of Present Knowledge
+     Relating to the Trypanosomes and Allied Forms. _Quar. Jour. Micro.
+     Sci._, Vol. 50, 1906, pp. 151-331. Characteristics; mode of
+     infection; effects on host; biological considerations; life-cycle,
+     etc. _Spirochaetae_; bibliography. Important article.
+
+     Trypanosomiasis and Sleeping Sickness. _Jour. Trop. Med. & Hyg._,
+     II, pp. 146-147, 162, 179-180, 196. List of recent literature.
+
+
+SLEEPING SICKNESS
+
+     BAGSHAWE, A.G. Recent Advances in Our Knowledge of Sleeping
+     Sickness. _Lancet_, II, 1909, pp. 1193-97. A summing up of the
+     important discoveries of the preceding year.
+
+     HEARSEY, H. Sleeping Sickness. _Jour. Trop. Met. & Hyg._, 12, Sept.
+     1, 1909, pp. 263-264. Report on work accomplished particularly in
+     relation to the distribution of _Glossina_ and other biting flies.
+
+     JARVIS, C. Sleeping Sickness. _Internat. Clinics_, Vol. II, 1904,
+     pp. 37-44. Shows the relation of the tsetse-fly to this disease.
+
+     LANKESTER, E.R. The Sleeping Sickness. _Quar. Review_, July, 1904,
+     p. 113. Discovery and early history; the fly, the parasite; other
+     related parasites. Relation of parasites to their hosts.
+
+     MINCHIN, E.A. The AEtiology of Sleeping Sickness. _Nature_, Nov. 15,
+     1906, pp. 56-59.
+
+     WOLLASTON, A.F.R. Amid the Snow Peaks of the Equator: a
+     Naturalist's Explorations Around Ruwenzori, with an _Account of the
+     Terrible Scourge of Sleeping Sickness_. _Nat. Geo. Mag._, XX, No.
+     3, Mar., 1909. Abstracted from "From Ruwenzori to the Congo" by
+     above author.
+
+     Reports of the Sleeping Sickness Com. of the Royal Society, I to
+     IX, 1903 to 1908. Studies and experiments with the trypanosomes and
+     flies concerned in this disease. Later articles by this commission
+     are to be found in the _Pro. Royal Soc._, Series B, LXXXI and
+     LXXXII.
+
+     Sleeping Sickness Bureau Bulletins, 1 to 14, 1908-1910. Records of
+     studies and experiments with trypanosomes and tsetse-flies, etc.
+
+     Transmission of Sleeping Sickness. Editorial in _Jour. Amer. Med.
+     Assn._, 53, Oct. 2, 1909, pp. 1104-05. Reviews recent experiments
+     and studies.
+
+
+ROCKY MOUNTAIN FEVER AND TICKS
+
+     ANDERSON, J.F. Spotted Fever (Tick Fever) of the Rocky Mountains.
+     _Hyg. Lab. Pub. Health and Mar. Hospt. Ser., Bull. 14_, 1903.
+     Distribution, aetiology, etc. Believes that ticks are responsible
+     for the transmission of the disease.
+
+     COOLEY, R.A. Preliminary Report on the Wood-tick. _Bull. 75, Mont.
+     Ex. Stn._, 1908. Sums up Ricketts' finding; notes on life-history
+     in laboratory and field.
+
+     KING, W.W. Experimental Transmission of Rocky Mountain Fever by
+     Means of the Tick. Preliminary note. _Pub. Health and Mar. Hospt.
+     Ser._, 21, July 27, 1906, pp. 863-864. Conveyed this fever from one
+     guinea-pig to another by means of the tick.
+
+     RICKETTS, H.T. The Transmission of Rocky Mountain Fever by the Bite
+     of the Wood-tick (_Dermacentor occidentalis_). _Jour. Amer. Med.
+     Assn._, Vol. 47, Aug., 1906, p. 358. Guinea-pig successfully
+     inoculated by means of tick.
+
+     RICKETTS, H.T. The Role of the Wood-tick (_Dermacentor
+     occidentalis_) in Rocky Mountain Spotted Fever. _Jour. Amer. Med.
+     Assn._, Vol. 49, July 6, 1907, pp. 24-27. Notes on experiments
+     conducted and studies made. Takes position that these experiments
+     connect the tick with the transmission of the fever.
+
+     ROBINSON, A.A. Rocky Mountain Spotted Fever. _Med. Rec._, Nov. 28,
+     1908. Occurrence and distribution of the disease; review of the
+     various theories in regard to its transmission. P.E. Jones of Salt
+     Lake believes it is transmitted by mosquitoes.
+
+     STILES, C.W. A Zooelogical Investigation Into the Cause,
+     Transmission and Source of Rocky Mountain Spotted Fever. _Hyg. Lab.
+     Pub. Health and Mar. Hospt. Ser., Bull. 20_, 1905. Does not find
+     the parasite that had been recorded by others, and finds no
+     evidence to indicate that the ticks transmit the disease.
+
+     WILSON, L.B., AND CHANNING, W.M. Studies in _Pyroplasmosis hominis_
+     (Spotted Fever or Tick Fever of the Rocky Mountains). _Jour. Infec.
+     Diseases_, 1, 1904, pp. 31-57. Evidence that the disease is
+     transmitted solely by means of the ticks.
+
+
+TICKS AND VARIOUS DISEASES
+
+     BANKS, NATHAN. Tick-borne Diseases and Their Origin. _Jour. Eco.
+     Ento._, Vol. I, No. 3, 1908, pp. 213-215. Shows how ticks may
+     become important disease-carriers by changing their hosts as the
+     normal host is exterminated, or for other reasons.
+
+     BANKS, NATHAN. A Revision of the Ixodoidea or Ticks of the United
+     States. _Tech. Series No. 15, Bull. of Bureau of Ento., U.S. Dept.
+     Agric._, 1908. Structure, life-history, classification, catalogue,
+     bibliography.
+
+     BARBER, C.A. The Tick Pest in the Tropics. _Nature_, 52, 1895, pp.
+     197-200. Direct and indirect effects of ticks on their hosts.
+
+     CHRISTY, C. _Ornithodoros moubata_ and Tick Fever in Man. _Brit.
+     Med. Jour._, Vol. II, 1903, p. 652. Relation of the tick to
+     _Filaria perstans_.
+
+     DUTTON, J.E., AND TODD, J.L. The Nature of Human Tick Fever in the
+     Eastern Part of the Congo Free State with Notes on the Distribution
+     and Bionomics of the Tick. Liverpool School of Tropical Medicine.
+     _Memoir_, 17, Nov., 1905, pp. 1-18.
+
+     HOOKER, W.A. A Review of the Present Knowledge of the Role of Ticks
+     in the Transmission of Disease. _Jour. Eco. Ento._, Vol. I, No. 1,
+     1908, p. 65. Review of the subject; table showing zooelogical
+     position of parasites transmitted by ticks. Table showing
+     zooelogical position of ticks.
+
+     HOOKER, W.A. Life-history, Habits and Methods of Study of the
+     Ixodoidea. _Jour. Eco. Ento._, Vol. 1, No. 1, 1908, p. 34. Notes on
+     several species, especially _M. annulatus_. Host relationship;
+     adaptations as factors in host relationship; mating; geographical
+     distribution; methods of breeding, etc.
+
+     HOOKER, W.A. Some Host Relations of Ticks. _Jour. Eco. Ento._, Vol.
+     2, No. 3, 1909, p. 251. Notes on ticks found on various hosts.
+
+     HUNTER, W.D., AND HOOKER, W.A. Information Concerning the North
+     American Fever Tick with Notes on Other Species. _Bull. 72, Bureau
+     of Ento._, 1907. Life-history, host relation, etc., of fever tick;
+     classification and notes on other species; bibliography divided
+     into sections.
+
+     LOUNSBURY, C.P. Habits and Peculiarities of Some South African
+     Ticks. _Rept. of the Brit. Assn. for the Advancement of Sci._, 1905
+     (South Africa), pp. 282-291.
+
+     MCCRAE, THOMAS. Relapsing Fever. _Osler's Mod. Med._, Vol. II, p.
+     245, 1907. AEtiology, symptoms, treatment, etc. (Apparently
+     communicated by blood-sucking insects.)
+
+     NEWSTEAD, R. On the Pathogenic Ticks Concerned in the Distribution
+     of Diseases in Man. _Brit. Med. Jour._, II, 1905, pp. 1695-97.
+     Classification and habits, particularly of _Ornithodoros moubata_.
+
+     NUTTALL, G.H.F. The Ixodoidea or Ticks. _Jour. of Roy. Inst. of
+     Pub. Health_, 1908. List of disease-bearing ticks. Position of
+     ticks, classification. Biology. Preventive measures.
+
+     NUTTALL, G.H.F. Piroplasmosis. _Jour. Roy. Inst. of Pub. Health_,
+     1908. What piroplasma are; diseases produced by them. Biology.
+
+     NUTTALL, GEO. F., and co-workers. _Canine Piroplasmosis_, Parts I
+     to VI. _Jour. Hyg._, Vol. 4, No. 2, Apr., 1904, to Vol. 7, No. 2,
+     Apr., 1907. A thorough discussion of the disease, the parasite
+     which causes it and the ticks which convey it.
+
+     POCOCK, R.I. Ticks. In Albutt and Rolleston's _System of Med._, II,
+     1907, pp. 187-203. Classification; description of the best-known
+     pathogenic species. Extended bibliography.
+
+     SKINNER, B. Preliminary Note on Ticks Infecting the Rats Suffering
+     from the Plague. _Brit. Med. Jour._, Vol. II, 1907, p. 457. Records
+     taking tick on a plague-sick rat and finding bacilli similar to
+     plague bacilli in connection with it.
+
+     SMITH, T., AND KILBORNE, F.L. Texas Fever. _U.S. Dept. Agric.
+     Bureau of Animal Industry, Bull. No. 1_, 1893. Records of the
+     experiments showing disease to be transmitted by ticks.
+
+     WELLMAN, F.C. Preliminary Note on Some Bodies Found in
+     Ticks--_Ornithodoros moubata_--Fed on Blood Containing Embryos of
+     Filaria. _Brit. Med. Jour._, July 20, 1907, p. 142. Believes that
+     _F. perstans_ is conveyed from man to tick and from tick to man.
+
+
+KALA-AZAR AND BEDBUGS
+
+     GIRAULT, A.A. The Indian Bedbug and Kala-azar Disease. _Sci._,
+     N.S., Vol. XXV, 1907, p. 1004. Indian bedbug is _C. rotundatus_
+     Sig. Its distribution. Summary of Dr. Patton's paper on
+     "Preliminary Report on the Development of the Leishman-Donovan Body
+     in the Bedbug."
+
+     PATTON, W.S. The Development of the Leishman-Donovan Parasite in
+     _Cimex rotundatus_. _Scientific Mem. of Gov. of India_, Nos. 27 and
+     31, 1907. Traces the development of this parasite; believes that
+     the bedbug is concerned in transmitting this disease.
+
+     See also Manson's _Tropical Diseases_, pp. 178-190.
+
+
+TEXT OR REFERENCE BOOKS IN WHICH THE RELATION OF INSECTS TO VARIOUS
+DISEASES IS DISCUSSED
+
+     ABBOTT, A.C. Hygiene of Transmissible Diseases. Phil., 1899.
+     Causes, modes of dissemination, prevention, treatment of infectious
+     and contagious diseases.
+
+     ALLBUTT, T.C., AND ROLLESTON, H.D. A System of Medicine. London,
+     1907. Vol. II, Pt. II, contains sections on tropical diseases;
+     animal parasites and the diseases they carry and zooelogical
+     articles dealing with Protozoa, mosquitoes, flies and ticks. All
+     articles have bibliographies, some of them quite extensive.
+
+     BALFOUR, ANDREW. Review of Recent Advances in Tropical Medicine.
+     Supplement to _Third Rept. Wellcome Research Lab._, London, 1908.
+     Notes, extracts and references in regard to important articles
+     during the preceding few months.
+
+     DANIELS, C.W. Studies in Laboratory Work, 2d ed., London, 1907. A
+     good discussion of animal parasites in the blood and blood-plasma;
+     development of malarial parasites in mosquitoes; flies, fleas,
+     lice, bedbugs, ticks, etc.
+
+     JACKSON, C.W. Tropical Medicine. Phil., 1907. Discusses diseases
+     due to bacteria and the parasites and uncertain causes. Splendid
+     recent summary of the various ways in which the different diseases
+     are disseminated.
+
+     LANGFELD, MILLARD. Introduction to Infectious and Parasitic
+     Diseases, Including Their Causes and Manner of Transmission. Phil.,
+     1907. Chapters on infection, animal parasites, avenues of exit and
+     portals of entry of infectious agents and parasites into the body.
+
+     MANSON, PATRICK. Lectures on Tropical Diseases. London, 1905.
+     Delivered at Cooper Medical College, 1905. Discusses several of
+     these diseases. Last chapter on problems in tropical medicine.
+
+     MANSON, PATRICK. Tropical Diseases. London, 1907, Diseases of the
+     tropics discussed in a very comprehensive manner. Considerable
+     attention given to the part played by insects in the transmission
+     of many of the diseases.
+
+     METCHNIKOFF, E. Immunity in Infectious Diseases. (Trans. from the
+     French by F.G. Binnie.) Cambridge, 1905. Splendid discussion of
+     various kinds of immunity. Insects referred to occasionally.
+
+     OSLER'S _Modern Medicine_. Vol. I, 1907, Pt. VI, Diseases Caused by
+     Protozoa. Part VII, Diseases Caused by Animal Parasites. Vol. II,
+     1907, Infectious Diseases. Vol. III, Infectious Diseases (cont.).
+     One of the best and most modern text-books; the volumes noted above
+     contain many references to the relation of insects to the
+     particular diseases under discussion.
+
+     PARK, W.H. Pathogenic Micro-organisms, Including Bacteria and
+     Protozoa. N.Y., 1908. These organisms comprehensively treated.
+
+     RICKETTS, H.T. Infection, Immunity and Serum Therapy. Chicago,
+     1906. Chapters on parasitism, infection, contagion, immunity,
+     various diseases, etc.
+
+     SCHEUBE, B. The Diseases of Warm Countries: a Handbook for Medical
+     Men. Trans. from Ger. by Pauline Falcke, London, 1903. Sections on
+     general infectious diseases, diseases caused by animal parasites,
+     etc. Good bibliography of each disease treated.
+
+     SIMPSON, W.J.R. The Principles of Hygiene as Applied to Tropical
+     and Subtropical Climates. London, 1908. Occasional references to
+     flies and mosquitoes as carriers of disease. Chapter XV deals with
+     malaria and other diseases caused by mosquitoes.
+
+     WILSON, J.C. Modern Clinical Medicine; Infectious Diseases. New
+     York and London, 1905. Chapters on yellow fever, malarial diseases
+     and plague; contains references to the relation of insects to these
+     diseases.
+
+
+MISCELLANEOUS ARTICLES
+
+     BALFOUR, ANDREW. Further Observations on Fowl Spirochaetosis. _Jour.
+     Trop. Med. & Hyg._, 12, Oct. 1, 1909, pp. 285-289. Ticks and lice
+     may carry this disease.
+
+     CHITTENDEN, F.H. Harvest-mites or "Chiggers." _Circular 77, U.S.
+     Dept. Agric. Bur. Ento._, 1906, pp. 1-16. Descriptions of these
+     pests and their habits. Remedies.
+
+     DOTY, A.H. The Means by Which Infectious Diseases Are Transmitted.
+     _Amer. Jour. of Med. Sci._, 138, July, 1909, pp. 30-39. Flies and
+     mosquitoes as disseminators of disease briefly discussed.
+
+     DUNCAN, F.M. Industrial Entomology: the Economic Importance of a
+     Study of Insect Life. _Jour. Roy. Soc. Arts_, May 22, 1908, pp.
+     688-696. A very interesting review of the subject of insects and
+     disease.
+
+     FLEXNER, SIMON. _Science_, N.S., Vol. 27, No. 682, Jan. 24, 1908,
+     pp. 133-136. On these pages the author discusses relation of
+     bacteria and Protozoa to human diseases.
+
+     GOLDBERGER, JOS., AND SHAMBERG, J.F. Epidemic of an _Utricaroid
+     dermatitis_ Due to a Small Mite (_Pediculoides ventricosus_) in the
+     Straw of Mattresses. _Pub. Health Rept., Pub. Health and Mar.
+     Hospt. Ser._, July 9, 1909, Vol. XXIV, No. 28. Experiments showed
+     that a certain skin disease occurring during summer was due to this
+     mite.
+
+     GORGAS, W.C. The Part Sanitation Is Playing in the Construction of
+     the Panama Canal. _Jour. Amer. Med. Assn._, 53, Aug. 21, 1909, pp.
+     597-599. Shows the changes that have been brought about by modern
+     sanitation and the destroying of the mosquitoes' breeding-places.
+
+     HOWARD, L.O. Hydrocyanic-acid Gas Against Household Insects.
+     _Circular 46, U.S. Dept. Agric., Div. of Ento._, 1902. Directions
+     for handling this dangerous gas.
+
+     KING, A.F.G. Insects and Disease; Mosquitoes and Malaria. _Pop.
+     Sci. Mo._, XXIII, 1883, pp. 644-658. Extended article in which the
+     author sums up the observations which led him to believe that
+     malaria and other diseases were transmitted by the mosquito. One of
+     the earliest articles on this subject; refers to an article in _New
+     Orleans Med. & Surg. Jour._, Vol. IV, 1848, pp. 563-601, by Josiah
+     Nott, who maintained that yellow fever was carried by mosquitoes.
+
+     MANSON, PATRICK. Recent Advances in Science and Their Bearing on
+     Medicine and Surgery. _Jour. Trop. Med. & Hyg._, XI, pp. 337-338,
+     Sept. 16, 1908. Discussion of parasites and disease and their
+     methods of dissemination.
+
+     NEWSTEAD, R., DUTTON, J.E., AND TODD, J.L. Insects and Other
+     Arthropoda Collected in the Congo Free State. _Ann. Trop. Med. &
+     Parasit._, Vol. 1, No. 1, Feb. 1, 1907, pp. 3-100. An interesting
+     paper giving notes on many insects that cause or carry disease.
+
+     NUTTALL, G.H.F. Spirochaetosis in Man and Animals. _Jour. of Roy.
+     Inst. of Pub. Health_, 1908. Why Spirochaetes should be regarded as
+     Protozoa. Classification; list of blood-inhabiting forms; relapsing
+     fevers; transmission by ticks and other Arthropods.
+
+     O'CONNELL, M.D. The Oversea Transport of Insect-borne Disease.
+     _Jour. Trop. Med. & Hyg._, XI, 43, Feb. 1, 1908. Refers to article
+     in same journal (Jan. 15) and points out that malaria is very
+     likely to be transmitted by mosquitoes in this way.
+
+     OSBORN, HERBERT. Insects Affecting Domestic Animals. _U.S. Dept. of
+     Agric., Div. of Ento., Bull. No. 5_, N.S., 1896. Discusses the
+     various insect pests of man and domestic animals Host lists.
+     Bibliography.
+
+     RICKETS, H.T., AND WILDER, R.M. The Typhus Fever of Mexico. _Jour.
+     Amer. Med. Assn._, LIV, No. 6, Feb. 5, 1910, p. 463. Believes this
+     disease is transmitted by insects, probably lice.
+
+     RITCHIE, JAMES. A Review of Current Theories Regarding Immunity.
+     _Jour. Hyg._, 2, 1902, pp. 215-285, and pp. 452-464. Discussion of
+     various theories. Bibliography.
+
+     SHIPLEY, A.E. On the Relation of Certain Cestode and Nematoda
+     Parasites to Bacterial Disease. _Jour. of Eco. Biol._, 4, 1909, pp.
+     61-71. Shows that these parasites may often cause serious diseases
+     by opening the way for malignant germs.
+
+     WARD, H.B. Spirochetes and Their Relationship to Other Organisms.
+     _Amer. Nat._, 42, 1908, No. 498, pp. 374-387. Still undecided as to
+     whether they belong with bacteria or Protozoa, probably the latter.
+
+     WARD, H.B. The Relation of Animals to Disease. _Science_, N.S., 22,
+     1905, pp. 193-203. An interesting, comprehensive review of the
+     subject.
+
+     WARD, HENRY B. Relation of Animals to Disease. _Transactions of
+     Amer. Micro. Soc._, Vol. 27, 1907, pp. 5-20. The various ways in
+     which animals may produce or carry disease.
+
+     The Oversea Transport of Insect-borne Diseases. Editorial in
+     _Jour. Trop. Med. & Hyg._, XI, Jan. 15, 1908, pp. 22-23. Points out
+     the danger of yellow fever, plague and other diseases being borne
+     overseas by infected insects.
+
+     The Society for the Destruction of Vermin. Editorial in _Jour.
+     Trop. Med. & Hyg._, XI, Apr. 15, 1908, p. 124. Tells of
+     organization of such society and its purposes.
+
+
+
+
+INDEX
+
+
+  Adams, S.H., 132.
+
+  Advisory Committee, 146.
+
+  Agramonte, Dr. Aristides, 123.
+
+  Alimentary canal, fly larvae in, 49.
+
+  Amoeba, 19.
+
+  Anopheles,
+    adults, 91;
+    eggs, 92;
+    habits of adults, 94;
+    larvae, 78, 79, 93;
+    pupae, 93;
+    resting position, 92;
+    species in U.S., 92.
+
+  Anthrax, 44;
+    and flies, 70.
+
+  Arthropoda, 26.
+
+  Asexual reproduction, 111.
+
+
+  Bacillus,
+    anthracis, 44;
+    icteroides, 124;
+    leprae, 171;
+    pestis, 150.
+
+  Bacillus carriers, 66.
+
+  Back-swimmers, 100.
+
+  Bacteria, 15;
+    saprophytic and parasitic, 17;
+    effect on host, 18;
+    dissemination, 18.
+
+  Bedbugs, 54, 147.
+
+  Banks, Nathan, 34.
+
+  Bell-animalcule, 22.
+
+  Berne, 51.
+
+  Birds as enemies of mosquitoes, 99.
+
+  Black-flies, 46.
+
+  Blackheads, 35.
+
+  Blow-flies, 48.
+
+  Blue, Dr. Rupert, 143.
+
+  Blue-bottle flies, 48.
+
+  Bot-flies, 50.
+
+  Break-bone fever, 169.
+
+  Breeze-fly, 44.
+
+  Buffalo-gnats, 46.
+
+
+  Calliphora vomitoria, 48.
+
+  Camphor, for mosquitoes, 102.
+
+  Cancer, 36.
+
+  Carroll, Dr. James, 123.
+
+  Castor-bean tick, 27.
+
+  Cattle tick, 29.
+
+  Cedar oil, for mosquitoes, 102.
+
+  Ceratophyllus,
+    faciatus, 153;
+    acutus, 156.
+
+  Cesspools, 72.
+
+  Chigger, 53.
+
+  Chigger-flea, 53.
+
+  Chigo, 30, 39.
+
+  Chigoe, 53.
+
+  Cholera, 68.
+
+  Chrysomyia macellaria, 47.
+
+  Cimex,
+    lectularis, 54;
+    rotundatus, 173.
+
+  Contagious diseases, 8.
+
+  Conjugation, 20.
+
+  Cooley, Prof. R.A., 33.
+
+  Craig, Dr. C.F., 118.
+
+  Ctenocephalus,
+    canis, 154;
+    felis, 154.
+
+  Culex,
+    fatigans, 96, 170;
+    pipiens, 98.
+
+
+  Dengue, 169.
+
+  Dermatobia cyaniventris, 51.
+
+  Dermatophilus penetrans, 53.
+
+  Diarrhea, 69.
+
+  Diptera, 43.
+
+  Diving beetles, 100.
+
+  Dragon-flies, 99.
+
+  Dysentery, 20.
+
+
+  Eggs,
+    of flies, 63;
+    of mosquitoes, 77;
+    of Anopheles, 92.
+
+  Egyptian opthalmia, 52.
+
+  Elephantiasis, 164.
+
+  Enemies of mosquitoes, 97.
+
+  Enteritis, 69.
+
+  Euglena, 21.
+
+  Eye-worm, 12.
+
+
+  Face-mite, 35.
+
+  Fighting mosquitoes,
+    adults, 101;
+    larvae, 103.
+
+  Fiji Islands, Anopheles in, 117.
+
+  Filaria bancrofti, 164.
+
+  Finlay, Dr. Charles, 124.
+
+  Fish, 100.
+
+  Flagella, 20.
+
+  Fleas, 52;
+    and plague, 142, 145, 147;
+    structure and habits, 151;
+    common species, 153;
+    on ground squirrels, 156;
+    remedies for, 157.
+
+  Flies, 43;
+    and typhoid, 65;
+    specks, 66;
+    and various diseases, 68.
+
+  Flesh-flies, 48.
+
+  Fumigating for mosquitoes, 102.
+
+
+  Gad-fly, 43.
+
+  Glossina palpalis, 163.
+
+  Golgi, Camillo, 109.
+
+  Grassi, Prof. G.B., 118.
+
+  Gray-flies, 47.
+
+  Ground squirrels and plague, 155.
+
+  Guinea-worm, 11.
+
+
+  Haemamoeba, 109.
+
+  Haematobia, 45.
+
+  Haemosporidiida, 24.
+
+  Haemotopinus spinulosus, 55.
+
+  Harvest-mite, 37.
+
+  Havana, yellow fever in, 131.
+
+  Hawaii, mosquitoes in, 98.
+
+  Hemiptera, 54.
+
+  Homalomyia canicularis, 49.
+
+  Hoplopsyllus anomalus, 156.
+
+  Horse bot-flies, 50.
+
+  House-flies, 57;
+    structure, 59;
+    how they carry bacteria, 62;
+    life-history and habits, 63;
+    fighting, 71;
+    and typhoid, 65.
+
+  Horse-flies, 43.
+
+  Howard, Dr. L.O., 59, 73.
+
+  Hyperparasitism, 3.
+
+
+  Immunity, 5.
+
+  Indian Plague Commission, 144.
+
+  Infectious diseases, 8.
+
+  Infusoria, 22.
+
+  Insects,
+    cause or carry disease, 40;
+    numbers, 40;
+    annual loss caused by, 41;
+    how they carry disease germs, 55.
+
+  Irrigating ditches, 104.
+
+  Itch-mite, 36.
+
+
+  Jackson, Dr. D.D., 67.
+
+  Jennings, 22.
+
+  Jiggers, 38, 53.
+
+  Jigger-flea, 53.
+
+
+  Kala-azar, 173.
+
+  Kerosene, 104.
+
+  Koch, 44.
+
+
+  Laemopsylla cheopus, 153.
+
+  Lamprey-eel, 2.
+
+  Lancisi, J.M., 107.
+
+  Larvae,
+    of flies, 64;
+    of mosquitoes, 78.
+
+  Laveran, A., 108.
+
+  Laverania, 109.
+
+  Lazear, Dr. Jessie W., 123.
+
+  Leeuwenhoek, Anton von, 22.
+
+  Lepra bacillus, 36.
+
+  Leprosy, 36, 70, 171.
+
+  Lice, 54.
+
+  Linnaeus, 76.
+
+  Little house-fly, 49.
+
+  Lock-jaw, 18.
+
+  Low, Dr. A., 118.
+
+  Lucilia spp., 48.
+
+  Lugger, Prof. Otto, 38.
+
+
+  Malaria,
+    early theories in regard to, 106;
+    parasite that causes, 108;
+    life history of parasite, 109;
+    parasite in mosquito, 113;
+    summary, 117;
+    experiments, 118.
+
+  Maggots, 63.
+
+  Malta or Mediterranean fever, 171.
+
+  Mange, 37.
+
+  Manure-fly, 59.
+
+  Manson, Sir Patrick, 112, 123.
+
+  Mastigophora, 20.
+
+  Melanin, 110.
+
+  Micrococcus melitensis, 171.
+
+  Microbes, 10.
+
+  Mites, 26, 35.
+
+  Mosquito, 76;
+    abdomen, 86;
+    adults, 81;
+    Anopheles, 91;
+    how they bite, 84;
+    effect of bite, 87;
+    blood, 90;
+    how they breathe, 89;
+    classification, 91;
+    and dengue, 169;
+    eggs, 77;
+    and elephantiasis, 164;
+    enemies, 77;
+    fighting, adults, 101;
+    larvae, 103;
+    larvae, 78;
+    and malaria, 106;
+    malarial parasite in, 113;
+    mouth-parts, 83;
+    other species, 96;
+    pupae, 80;
+    salivary glands, 87;
+    thorax, 85;
+    and yellow fever, 94, 120.
+
+  Mouth-parts,
+    of fly, 60;
+    of mosquito, 83.
+
+  Mus,
+    norvegicus, 154;
+    rattus, 154.
+
+
+  Nanga, 45.
+
+  Nematodes, 164.
+
+  New Orleans, yellow fever in, 120, 132.
+
+  Noctiluca, 21.
+
+  No-see-ums, 46.
+
+
+  Ochromyia anthropophaga, 49.
+
+  Oil of citronella, 102.
+
+  Oil of pennyroyal, 102.
+
+  Oriental sore, 174.
+
+  Ornithodorus moubata, 34.
+
+  Oscinidae, 52.
+
+  Otospermophilus beecheyi, 155.
+
+  Oxwarbles, 50.
+
+
+  Panama Canal zone, 135.
+
+  Paramoecium, 22.
+
+  Parasite,
+    defined, 1;
+    classes of, 4;
+    in new regions, 5;
+    diseases caused by, 7;
+    effect on host, 9;
+    relation to host, 14.
+
+  Parasitism, 3.
+
+  Pasteur, L., 44.
+
+  Pearls, 13.
+
+  Piroplasma bigeminum, 29.
+
+  Plague,
+    early history of, 142;
+    fleas that transmit, 153;
+    and flies, 70;
+    and ground squirrels, 155;
+    how combatted in San Francisco, 143;
+    results of other investigations, 150;
+    Verjbitski's experiments, 147;
+    work of Indian Plague Commission, 146.
+
+  Plasmodium, 109.
+
+  Protozoa, 19;
+    classes of, 20.
+
+  Proboscis,
+    of fly, 60;
+    of mosquito, 80.
+
+  Privies, 72.
+
+  Privy-fly, 59.
+
+  Pseudopodia, 20.
+
+  Psoroptes communis, 37.
+
+  Pulex irritans, 154.
+
+  Punkies, 46.
+
+  Pupae,
+    of house-flies, 64;
+    of mosquitoes, 80.
+
+  Pyrethrum, 102.
+
+
+  Rats,
+    and plague, 143, 145;
+    species of, 154.
+
+  Red-bugs, 38.
+
+  Reed, Dr. Walter, 123.
+
+  Relapsing fever, 21, 33.
+
+  Rhizopoda, 20.
+
+  Ricketts, Dr. H.F., 32.
+
+  Rio de Janeiro, yellow fever in, 137.
+
+  Rocky Mountain spotted fever, 32.
+
+  Ross, Ronald, 112.
+
+  Rucker, Dr. W.C., 143.
+
+
+  Sacculina, 2.
+
+  Salivary glands, 84, 87.
+
+  Salt marshes, 97, 105.
+
+  Sambon, Dr. L.W., 118.
+
+  Sand-fleas, 53.
+
+  Saprophytic bacteria, 17.
+
+  Sarcophaga spp., 48.
+
+  Sarcoptes scabiei, 37.
+
+  Scab, 37.
+
+  Screw-worm, 47.
+
+  Seed-ticks, 27, 30.
+
+  Sheep bot-flies, 51.
+
+  Simmond, Dr. P.L., 145.
+
+  Siphonaptera, 52.
+
+  Skinner, Dr. H., 159.
+
+  Sleeping sickness, 21, 161.
+
+  Slipper animalcule, 22.
+
+  Small-pox, 70.
+
+  Smith, Dr. Theobald, 29.
+
+  Smudges, 102.
+
+  Sore-eye, 52.
+
+  Spiders, 26.
+
+  Spiracles, 89.
+
+  Spirochaeta, 21, 130.
+
+  Spore formation, 24.
+
+  Spores, 24.
+
+  Sporozoa, 22.
+
+  Spotted fever, 32.
+
+  Stable-fly, 44, 75.
+
+  Stegomyia,
+    calopus, 94, 98, 139;
+    scutellaris, 96.
+
+  Sticklebacks, 101.
+
+  Stomoxys calcitrans, 44.
+
+  Sulphur, 102.
+
+  Surra, 45.
+
+
+  Tabanus, 45.
+
+  Tahiti, mosquitoes in, 96.
+
+  Tapeworms, 2.
+
+  Tetanus, 18.
+
+  Texas fever, 28.
+
+  Theobald, Dr. F.V., 76.
+
+  Ticks, 26.
+
+  Tide-water minnows, 101.
+
+  Tobacco smoke, 102.
+
+  Top-minnows, 98, 101.
+
+  Torcel, 51.
+
+  Tracheae, 89.
+
+  Tracheal gills, 79.
+
+  Trichina, 2.
+
+  Trypanosome, 45, 161.
+
+  Trypanosoma,
+    evansi, 45;
+    brucei, 45;
+    lewisi, 162;
+    gambiensi, 162.
+
+  Tsetse-fly, 45, 163.
+
+  Tubercular bacilli, 69;
+    germs, 69.
+
+  Typhoid-fly, 57, 59.
+
+
+  Vaughan, Dr. W.C., 67.
+
+  Ver macque, 51.
+
+  Verjbitski, D.T., 147.
+
+  Vorticella, 22.
+
+
+  Water-boatmen, 100.
+
+  Water-troughs, 104.
+
+  Whip-bearers, 20.
+
+  Whirligig beetles, 100.
+
+  White, Surgeon J.H., 134.
+
+  Wrigglers, 78.
+
+
+  Yellow fever, 120;
+    Commission, 123;
+    early observations on, 121;
+    experiments, 125;
+    danger of in Pacific Islands, 140;
+    in Havana, results of work on, 131;
+    history of in United States, 120;
+    mosquito, 94;
+    habits of, 95;
+    in Panama Canal zone, 135;
+    in Rio de Janeiro, 137;
+    summary of results of work on, 129.
+
+
+
+
+
+End of the Project Gutenberg EBook of Insects and Diseases, by Rennie W. Doane
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