diff options
| -rw-r--r-- | .gitattributes | 4 | ||||
| -rw-r--r-- | LICENSE.txt | 11 | ||||
| -rw-r--r-- | README.md | 2 | ||||
| -rw-r--r-- | old/69062-0.txt | 3265 | ||||
| -rw-r--r-- | old/69062-0.zip | bin | 51286 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h.zip | bin | 2006039 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/69062-h.htm | 4208 | ||||
| -rw-r--r-- | old/69062-h/images/fig1.jpg | bin | 57170 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/fig2.jpg | bin | 39636 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/fig3.jpg | bin | 62633 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/fig4.jpg | bin | 14485 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/fig5.jpg | bin | 35270 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/fig5lge.jpg | bin | 58216 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/i_cover.jpg | bin | 148476 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl1a.jpg | bin | 75157 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl1alge.jpg | bin | 168980 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl1b.jpg | bin | 86579 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl1blge.jpg | bin | 205015 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl2a.jpg | bin | 70153 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl2alge.jpg | bin | 150596 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl2b.jpg | bin | 76921 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl2blge.jpg | bin | 190915 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl3a.jpg | bin | 77656 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl3alge.jpg | bin | 161880 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl3b.jpg | bin | 64968 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl3blge.jpg | bin | 152357 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/pl4.jpg | bin | 61756 -> 0 bytes | |||
| -rw-r--r-- | old/69062-h/images/seal.jpg | bin | 16252 -> 0 bytes |
28 files changed, 17 insertions, 7473 deletions
diff --git a/.gitattributes b/.gitattributes new file mode 100644 index 0000000..d7b82bc --- /dev/null +++ b/.gitattributes @@ -0,0 +1,4 @@ +*.txt text eol=lf +*.htm text eol=lf +*.html text eol=lf +*.md text eol=lf diff --git a/LICENSE.txt b/LICENSE.txt new file mode 100644 index 0000000..6312041 --- /dev/null +++ b/LICENSE.txt @@ -0,0 +1,11 @@ +This eBook, including all associated images, markup, improvements, +metadata, and any other content or labor, has been confirmed to be +in the PUBLIC DOMAIN IN THE UNITED STATES. + +Procedures for determining public domain status are described in +the "Copyright How-To" at https://www.gutenberg.org. + +No investigation has been made concerning possible copyrights in +jurisdictions other than the United States. Anyone seeking to utilize +this eBook outside of the United States should confirm copyright +status under the laws that apply to them. diff --git a/README.md b/README.md new file mode 100644 index 0000000..7ba2f48 --- /dev/null +++ b/README.md @@ -0,0 +1,2 @@ +Project Gutenberg (https://www.gutenberg.org) public repository for +eBook #69062 (https://www.gutenberg.org/ebooks/69062) diff --git a/old/69062-0.txt b/old/69062-0.txt deleted file mode 100644 index f154af4..0000000 --- a/old/69062-0.txt +++ /dev/null @@ -1,3265 +0,0 @@ -The Project Gutenberg eBook of A bacteriological study of ham -souring, by C. N. McBryde - -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world 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. If you are not located in the United States, you -will have to check the laws of the country where you are located before -using this eBook. - -Title: A bacteriological study of ham souring - -Author: C. N. McBryde - -Release Date: September 28, 2022 [eBook #69062] - -Language: English - -Produced by: Charlene Taylor, Les Galloway and the Online Distributed - Proofreading Team at https://www.pgdp.net (This file was - produced from images generously made available by The - Internet Archive/American Libraries.) - -*** START OF THE PROJECT GUTENBERG EBOOK A BACTERIOLOGICAL STUDY OF -HAM SOURING *** - - Transcriber’s Notes - -Obvious typographical errors have been silently corrected. Several -tables have been divided with duplication of the first column because -of their excessive width. - -Italics are represented thus _italic_. - - - - - Issued March 17, 1911. - - U. S. DEPARTMENT OF AGRICULTURE, - BUREAU OF ANIMAL INDUSTRY.—BULLETIN 132. - A. D. MELVIN, CHIEF OF BUREAU. - - - A BACTERIOLOGICAL STUDY - OF HAM SOURING. - - - BY - - C. N. McBRYDE, M. D., - _Senior Bacteriologist, Biochemic Division_. - - [Illustration: UNITED STATES DEPARTMENT OF AGRICULTURE.] - - - WASHINGTON: - GOVERNMENT PRINTING OFFICE. - 1911. - - - - - THE BUREAU OF ANIMAL INDUSTRY. - - - _Chief_: A. D. MELVIN. - _Assistant Chief_: A. M. FARRINGTON. - _Chief Clerk_: CHARLES C. CARROLL. - _Animal Husbandry Division_: GEORGE M. ROMMEL, chief. - _Biochemic Division_: M. DORSET, chief. - _Dairy Division_: B. H. RAWL, chief. - _Inspection Division_: RICE P. STEDDOM, chief; R. A. RAMSAY, - MORRIS WOODEN, and ALBERT E. BEHNKE, associate chiefs. - _Pathological Division_: JOHN R. MOHLER, chief. - _Quarantine Division_: RICHARD W. HICKMAN, chief. - _Zoological Division_: B. H. RANSOM, chief. - _Experiment Station_: E. C. SCHROEDER, superintendent. - _Editor_: JAMES M. PICKENS. - - - - - LETTER OF TRANSMITTAL. - - - UNITED STATES DEPARTMENT OF AGRICULTURE, - BUREAU OF ANIMAL INDUSTRY, - _Washington, D. C., November 2, 1910_. - -SIR: I have the honor to transmit and to recommend for publication as -a bulletin of this Bureau a paper entitled “A Bacteriological Study -of Ham Souring,” by Dr. C. N. McBryde, senior bacteriologist in the -Biochemic Division of this Bureau. - -The souring of hams is a source of considerable loss in the -meat-packing industry, and the cause of this trouble has heretofore -been in doubt. Dr. McBryde’s paper presents the results of an -exhaustive study of the subject, from which it appears that he has -succeeded in discovering the true cause of the trouble. Besides a -description of the experimental work the paper discusses methods of -preventing the souring of hams and the proper disposal of those which -have become affected. - - Respectfully, A. D. MELVIN, - _Chief of Bureau_. - - Hon. JAMES WILSON, - _Secretary of Agriculture_. - - - - - CONTENTS. - - - Page. - - Introductory 7 - - Method of curing hams 8 - - Definition of souring 10 - - Classification of sour hams and location of sour areas 10 - - Method of detecting sour hams 12 - - Theories in regard to ham souring 12 - - Previous experimental work to determine cause of ham - souring 13 - - The present experiments 14 - - Media employed 14 - - Method of procedure in examining hams 15 - - Results of examination of sour and sound hams 16 - - Histological changes in sour hams 17 - - Chemical analyses of sour and sound hams 18 - - Bacteriological examination of sour and sound hams 20 - - Inoculation experiments with hams 21 - - Probable method by which ham-souring bacillus enters hams 33 - - Possibility of infection prior to slaughter 33 - - Possible infection from pickling fluids 34 - - Experiment to show whether infection takes place - from the curing pickle 34 - - Possible infection through manipulation or handling 35 - - Infection from ham thermometers 35 - - Experiment to show whether hams become infected - from ham thermometers 37 - - Infection from pumping needles 41 - - Infection from billhooks 42 - - Biological and morphological characteristics of the - ham-souring bacillus 43 - - Conditions favorable to growth 43 - - Growth on different culture media 43 - - Morphology 46 - - Spore formation 46 - - Resistance to heat and chemical agents 47 - - Gas production 47 - - Acid production 48 - - Pathogenic properties 48 - - Nature of the bacillus 48 - - Prevention of ham souring 50 - - General summary and conclusions 53 - - Acknowledgments 55 - - - - - ILLUSTRATIONS. - - - PLATES. - - Page. - - PLATE I. Fig. 1.—Section of muscular tissue from sound ham, - showing muscle fibers cut longitudinally; nuclei sharply - defined and cross striation distinct. Fig. 2.—Section of - muscular tissue from sour ham, showing muscle fibers cut - longitudinally; nuclei undergoing disintegration and cross - striation indistinct 16 - - II. Fig. 1.—Section through muscular tissue of ham which has - undergone natural or spontaneous souring, showing distribution - of bacilli between the muscle fibers, which are cut obliquely. - Fig. 2.—Section through muscular tissue of ham which has - undergone natural or spontaneous souring, showing individual - bacilli between the muscle fibers, which are cut somewhat - obliquely 18 - - III. Fig. 1.—Section through muscular tissue of artificially soured - ham, showing distribution of bacilli between the muscle fibers, - which are shown in cross section. Fig. 2.—Section through - muscular tissue of artificially soured ham, showing individual - bacilli between the muscle fibers, which are cut longitudinally - 26 - - IV. Glucose bouillon culture in Smith fermentation tube at four - days 48 - - - TEXT FIGURES. - - FIG. 1. Cross section through body of ham, with sour areas - indicated by shading and dotted lines 11 - - 2. Cross section through body of ham to show method of sampling - for chemical analysis 18 - - 3. Cross section through body of artificially soured ham, - showing sour areas and points at which cultures were taken 25 - - 4. Diagrammatic views showing construction of ham thermometer 36 - - 5. Ham-souring bacillus (_Bacillus putrefaciens_), grown on - egg-pork medium 46 - - - - - A BACTERIOLOGICAL STUDY OF HAM SOURING. - - - - - INTRODUCTORY. - - -The souring of hams is a matter of considerable importance to those -engaged in the meat-packing industry, and has been the occasion of no -little worry, as in even the best-regulated packing establishments -the yearly losses it entails are considerable. The subject has given -rise to much speculation on the part of those engaged in the curing -of meats, as to the cause of the trouble and how it may be remedied, -and has received considerable attention in a practical way, but little -seems to have been done in a scientific way toward determining the -cause and nature of ham souring. - -In a well-regulated meat-packing establishment the loss from ham -souring is usually figured at about one-tenth of 1 per cent of the -total weight of hams cured. At first thought this would seem but a -small loss, but when one reflects that in a single large packing -establishment some 3,000,000 hams are cured during the year, the loss, -when figured out, is considerable. Taking 15 pounds as the average -weight of a ham, 3,000,000 hams would represent 45,000,000 pounds of -meat. Figuring the loss from souring on the basis mentioned, the amount -of meat condemned and destroyed during the year would be 45,000 pounds. -Assuming that hams sell at an average wholesale price of 15 cents a -pound, the yearly loss for a single plant which cures 3,000,000 hams a -year would be nearly $7,000. - -While one-tenth of 1 per cent of the total weight of hams cured would -represent the loss from souring in a well-regulated establishment, -statistics obtained through Government meat inspectors show that -0.25 per cent would more nearly represent the loss for the entire -country. During the fiscal year from July 1, 1908, to June 30, 1909, -some 670,000,000 pounds of hams were placed in cure in packing -establishments subject to Government inspection. Estimating the loss -from souring at 0.25 per cent, the total amount of meat condemned -and destroyed as sour would be 1,675,000 pounds. At 15 cents a pound -the total annual loss from ham souring in packing houses subject to -Government inspection would figure up something over a quarter of a -million of dollars. - -The problem of ham souring, therefore, is quite an important one from a -practical and financial standpoint; but aside from these considerations -it is also a subject of considerable scientific interest, and in -view of the fact that all sour meats are condemned under the Federal -regulations governing meat inspection it has seemed fitting that this -question should be made the subject of scientific investigation on the -part of the Bureau which is charged with the administration of this -inspection. - -The investigation reported in this paper has been conducted chiefly -along bacteriological lines, and has been confined entirely to the wet -method of curing hams, as this method is the one generally used in -American packing houses. - - - - - METHOD OF CURING HAMS. - - -In order to make clear certain points in regard to the nature and -occurrence of ham souring and to insure a better understanding of the -experiments which are to be described later, it would seem best to -begin with a brief outline of the method of curing hams as practiced in -the larger packing establishments of the country. This description is -merely a general outline of the method of preparing hams for cure and -the method of handling hams while in cure, and deals chiefly with those -points that bear on the question of souring. - -After the slaughtered animal has been cleaned, scraped, eviscerated, -washed, and split down the middle, the carcass is usually allowed to -hang for an hour or so in a large room open to the outside air, known -as the “hanging floor.” This is done with a view to getting rid of a -certain amount of the body heat before the carcass is run into the -chill rooms, and effects a saving in refrigeration. - -The carcasses are next run into “coolers” or chill rooms, and subjected -to refrigeration with a view to ridding them entirely of their body -heat. The coolers are large rooms fitted with brine pipes and capable -of accommodating several hundred carcasses. The temperature of the -coolers when the carcasses are run in is about 32° F. When filled, the -temperature of the cooler rises to about 45° F., owing to the heat -given off from the carcasses. The temperature is then gradually reduced -to 28 or 30° F. Hog carcasses are left in the coolers as a rule for -forty-eight hours, at the end of which time they are stiff and firm, -but not frozen. The temperature of the chill rooms is always carefully -watched, thermometer readings being made every few hours and duly -recorded. The temperature of the carcasses is always tested when they -leave the chill room. In those plants provided with a hanging floor, a -certain number of the carcasses are also tested before they are sent to -the chill rooms in order to determine the amount of heat lost on the -hanging floor. - -The carcasses are tested by means of an especially constructed -thermometer, known as a “ham thermometer,” which has a pointed metal -protector so that it can be thrust into the body of the ham. (See fig. -4.) The ham has been rightly selected as the proper portion of the -carcass at which to take the temperature, as it constitutes the largest -mass of muscular tissue in the carcass and holds the body heat longer -than any other portion. In taking the temperature, the thermometer -is thrust deep into the body of the ham so that the point of the -thermometer rests alongside or a little behind the upper portion of the -femur or middle bone, the latter being used as a guide in introducing -the thermometer. A certain number of the carcasses from each cooler -are tested in this way as a check on the refrigeration. The inside -temperature of the hams when they leave the chill rooms should be about -34° F. - -The carcasses are next cut up and the hams trimmed for pickling. In -some houses the hams are given an additional chilling of 48 hours after -they are cut from the carcasses, but this is not done as a rule, nor -does it seem to be necessary. - -The hams are now sent to the pickling rooms, or “sweet pickle -department,” as this branch of the packing house is designated, and -here a certain number are again tested with a thermometer, as described -above. This test is carried out by the foreman in charge of the sweet -pickle department in order that he may satisfy himself that the -hams are properly chilled before they go into the pickle and as an -additional check on the refrigeration. - -The hams are now ready to be “pumped,” and this pumping, as will be -shown later, constitutes an important step in a successful cure. -Pumping consists in forcing a strong brine solution containing -saltpeter into the muscular tissues of the ham, and is accomplished by -means of a large, hollow, fenestrated needle connected by means of a -rubber hose with a powerful hand pump. The needle is introduced along -the bone, the latter being used as a guide. - -In all of the larger packing establishments two general methods of -curing hams are followed, the two methods being designated as the -“fancy” or “mild cure” and the “regular cure,” the term “cure” being -used to designate the curing period. Various trade names are given -by the different packing establishments to the hams cured by these -methods. In the fancy cure the hams are pumped in the shank only, -whereas in the regular cure they are pumped in both body and shank. -The same pumping pickle is generally used for the two cures. It is a -significant fact that the greater proportion of the “sours” are found -among the fancy or mild cure hams. This point will be discussed farther -on in connection with some experiments to be described later. - -The actual curing is usually carried out in large vats which hold about -1,400 pounds of meat or some hundred hams. The hams are packed in the -vats in layers and are entirely covered with the pickling solution or -brine. A certain proportion is always observed between the weight of -the meat and the amount of the solution. The pickling solution, or -“pickle,” as it is termed, is a brine solution containing saltpeter -and sugar. The composition of the pickle varies somewhat with the -different packing establishments. The fancy-cure hams are usually cured -in a milder pickle, that is, one that contains less salt and saltpeter -than the pickle used in the regular cure, although in some packing -establishments the same curing pickle is used for the two cures, the -only difference being the additional pumping given the regular-cure -hams. The pickling rooms, or “cellars,” as they are called, are held at -a temperature of 34° to 36° F., and the pickling solutions are always -chilled to this temperature before being used. - -The hams are allowed to remain in cure for about 60 days, and during -this time are “overhauled” several times. Overhauling consists in -throwing the hams from the vat in which they are packed into a -neighboring empty vat, and then transferring the pickle to the new vat. -The pickle is not changed, and the same pickle follows the hams through -the entire curing process. The object in overhauling is to stir up the -pickle and expose fresh surfaces of the meat to its action. - -Hams are also cured in tierces which hold about 300 pounds of meat. -In the tierce cure, the hams are packed in the tierces, the latter -are then headed up, the pickling solution is next run in through the -bunghole, so as to fill the tierce entirely, and a wooden stopper is -finally driven into the bunghole. The tierces are rolled back and forth -across the floor on dates corresponding to the dates of overhauling in -the vat cure. The object of the rolling is to stir up the pickle, and -in this way it corresponds to overhauling in the vat cure. - - - - - DEFINITION OF SOURING. - - -To the meat inspector, a sour ham is one which has a tainted or “off” -odor, that is, any odor which deviates from the normal. The odor may be -very slight, so slight that at times only the trained meat inspector -can detect it. When slight, the odor is elusive and hard to define, but -when pronounced it has a distinctly putrefactive quality. When not very -pronounced, the odor possesses, as a rule, a slightly sour quality, -chemically speaking, and at times this sour quality may be quite -marked; hence the term “sour ham,” or “sour” has originated. In a badly -soured ham—using the term “sour” in the packing-house sense to denote -any ham that is tainted—the odor loses this sour quality and becomes -distinctly putrefactive in nature. - - - - - CLASSIFICATION OF SOUR HAMS AND LOCATION OF SOUR AREAS. - - -Sour hams are classed as “shank sours” and “body sours,” according to -the location of the souring, and these may be “light” or “heavy.” When -the souring is very pronounced, the ham is termed a “stinker.” - -Souring appears to start, as a rule, around the stifle joint -(femorotibial articulation), and extends upward into the body of the -ham. - -In quite a large proportion of the hams which are sour in the -body—probably from 40 to 50 per cent—the souring extends through to -the bone marrow of the femur or middle bone, and the sour odor is at -times more pronounced in the bone marrow than in the meat. The odor -of the bone marrow, when pronounced, is strongly suggestive of a -dissecting-room odor, and is distinctly putrefactive in quality. - -In the case of light body sours the sour odor is confined to a small -area immediately around the bone, and may be so slight that it is -detected only with difficulty. In such hams the bone marrow is apt to -be sweet, and it is not until the souring becomes more extensive that -the bone marrow becomes involved. - -[Illustration: FIG. 1.—Cross section through body of ham, with sour -areas indicated by shading and dotted lines.] - -The distribution of the sour area in the body of a well-developed sour -is shown in figure 1. - -In the case of a well-developed body sour the sour area is more -pronounced near the bone, as represented in figure 1 by the shaded -area, and may extend out into the body of the ham for a variable -distance, according to the degree of souring, as represented by the -dotted lines, gradually fading off toward the margins, where it may be -imperceptible or entirely wanting. - -In the pronounced sours, termed “stinkers,” the odor pervades the -entire ham, and is of a distinctly putrefactive quality. - -In shank sours, the souring is more or less confined to the shank, or -the region about the tibio-femoral articulation, but may extend upward -into the lower portion of the body of the ham. - - - - - METHOD OF DETECTING SOUR HAMS. - - -Souring is detected and located by means of a pointed metal instrument -known as a “ham trier,” which resembles a long, slightly flattened ice -pick. The trier is thrust into the ham at different points along the -bone, rapidly withdrawn, and the odor which clings to the metal noted. -The trained inspector works very rapidly, and is able to detect even -the slightest sour or off odor which might be imperceptible to one not -trained to the work. At the end of the cure all hams are tested with -the trier under the supervision of Government meat inspectors. - -Hams are also given what is called the “30-day inspection” by plant -inspectors during the process of curing. An average ham weighing -from 14 to 16 pounds requires about 60 days to cure, and at the end -of 30 days a certain number of hams in each run are usually tested -to see how the cure is progressing. If no sour hams are discovered -at this inspection the packer knows that the cure is progressing -satisfactorily, and moreover he feels sure that his hams will finish -satisfactorily, for experience has taught him that souring develops -within the first four weeks of the curing period, and if his hams are -sweet at the end of this time, he can feel practically sure that no -sours will develop later on. - - - - - THEORIES IN REGARD TO HAM SOURING. - - -The theories as to the cause of souring are many and varied. The -majority of them are pure speculation and have no foundation upon -observed facts. A few of these theories may be enumerated to show how -wide and varied has been the speculation upon this subject. - -A theory which is quite prevalent among packing-house employees -attributes souring to overheating of the animal previous to slaughter, -but tests were made by driving hogs to the point of exhaustion just -prior to slaughter and curing the hams from these animals in comparison -with hams taken from animals which had been rested prior to slaughter, -with no difference in the cured product; that is, the hams taken from -overheated hogs cured equally as well as those taken from rested hogs. - -Another theory attributes souring to a diseased condition of the meat. -Prior to the enforcement of the Federal regulations governing meat -inspection there might have been some ground for such a supposition, -but this theory could not hold at the present time, in view of the -thorough and efficient inspection now in force, for it can be safely -said that no diseased meat now passes the Government inspectors, and -therefore no diseased meat goes into cure in inspected houses. In -order to test this theory, however, hams were secured from a number -of condemned animals which showed various diseased conditions, such -as hog cholera, pyemia, septicemia, scirrhous chord, etc., and these -hams were cured in comparison with hams taken from normal hogs. It was -found that the hams taken from the diseased hogs cured equally as well -as those taken from healthy hogs. The hams from the diseased hogs were -destroyed after the experiment, as the meat taken from diseased animals -was of course not considered fit for consumption, the object of the -experiment being merely to determine whether or not souring is caused -by diseased conditions. - -Another theory attributes souring to imperfect or too rapid chilling -of the meat before it is put in pickle, and places the blame upon the -refrigeration. According to this theory, souring results when the meat -is chilled too suddenly, the idea being that by the rapid congealing of -the juices of the meat a coating is formed on the outside of the ham -whereby the animal heat is prevented from escaping from the interior, -leaving the meat next to the bone at a higher temperature than the -outside of the ham. - -In order to test this last theory, a number of hog carcasses were run -direct from the killing floor to a cooler at 28° F. and a like number -of carcasses of the same average weight which had been allowed to stand -for two hours at the outside temperature of the air (53° F.) were -placed in the same cooler. The carcasses which had hung for two hours -in the air had lost an average of 14 degrees in temperature before -going to the cooler. The temperature of the cooler rose to 29° F. after -the carcasses were put in, but was soon reduced to 28° F. and held at -this temperature. The temperatures of the hams were taken at the end -of 24 hours, and practically no difference was found in the inside -temperatures of the two lots; that is, the hams on the hot carcasses -which were subjected to a sudden chilling exhibited practically the -same inside temperature (i. e., next to the bone) as those which had -cooled for two hours at the temperature of the air before being placed -in the cooler. - -Still another theory attributes souring to lack of penetration of the -pickling fluids, but analyses of sour and sound hams do not seem to -bear out this theory. The rate of penetration of the pickling fluids, -however, would seem to have some bearing on the subject, and this point -will be discussed later in connection with some laboratory experiments -on the inhibitory effects of sodium chlorid and potassium nitrate. - -So much for the more commonly accepted theories which have been -advanced to explain ham souring. - - - - - PREVIOUS EXPERIMENTAL WORK TO DETERMINE CAUSE OF HAM SOURING. - - -A review of the literature reveals but one article bearing directly on -the subject of the cause of ham souring. - -In June, 1908, Klein[1] published in the London Lancet an article -on “miscured” hams. He describes a miscured ham as one which has a -distinctly putrid smell, and the tainted areas he describes as varying -in color from a dirty gray to a dirty green, the muscular tissues in -the strongly tainted areas being swollen and soft, or jelly-like. From -such hams he isolated a large nonmotile, nonspore-bearing, anaerobic -bacillus which he calls _Bacillus fœdans_. He cultivated the organism -on different media and obtained from the cultures a putrid odor -resembling that of the ham from which the culture was obtained, but -did not attempt to produce tainting by injecting sound hams with the -bacillus. - -[1] Klein, E. On the nature and causes of taint in miscured hams. The -Lancet, vol. 174, London, June 27, 1908. - -While there can be little doubt that Klein’s bacillus was the cause of -the tainting in those hams which he examined, the proof would certainly -have been stronger had he injected sound hams with cultures and thus -proven that he could reproduce tainting experimentally by means of his -bacillus. Klein examined only dry-cured hams and does not state the -temperature at which they were cured. He fails to offer any explanation -as to how the bacillus gained entrance into the hams. - - - - - THE PRESENT EXPERIMENTS. - - - MEDIA EMPLOYED. - -After considerable experimentation as to a suitable culture medium for -the bacteriological study of sour hams, a modification of the “egg-meat -mixture” used by Rettger[2] in his studies on putrefaction was found -to be the most satisfactory. This medium, which consists of chopped -meat and egg albumen, furnishes an excellent medium for the growth of -putrefactive organisms which rapidly break down the proteids of the -meat, giving rise to the characteristic odors of putrid decomposition. -Rettger used chopped beef and egg albumen, but for the present work -chopped pork was substituted for the beef, as affording a more suitable -medium for the growth of organisms accustomed to growth in pork hams. -The modified medium is prepared as follows: - -A. One-half pound of lean pork, freed from excess of fat and sinew, -is finely chopped in a meat chopper, 250 cubic centimeters of water -is then added, the meat acids are neutralized with sodium carbonate, -and the mixture is heated in an Arnold sterilizer for 30 minutes, with -occasional stirring. It is then set away in a cold place for several -hours. A small amount of fat collects at the top in the form of a fatty -scum, as it is impossible to remove all of the fat from the meat before -it is chopped. The fatty scum, which hardens upon standing in the cold, -is now removed. - -B. The whites of three eggs are mixed with 250 cubic centimeters of -water. The mixture is rendered neutral to phenolphthalein by means -of dilute hydrochloric acid and heated for 30 minutes in the Arnold -sterilizer, with occasional stirring. - -A and B are now mixed and 2.5 grams (0.5 per cent) of powdered calcium -carbonate added. The mixture is next run into large sterile test tubes, -or sterile flasks, and sterilized in an Arnold sterilizer on three -successive days. - -[2] Rettger, L. F. Studies on putrefaction. Journal of Biological -Chemistry, vol. 2, 1906. - -In addition to the egg-pork mixture described above, culture tubes -of agar and bouillon prepared from pork instead of beef, with the -addition of 1 per cent of glucose, were also used; but the best results -were obtained with the egg-pork medium, as with this medium, the -early development of sour or putrefactive odors furnished a valuable -indication as to the presence of organisms capable of producing sour or -putrefactive changes in meat. - - - METHOD OF PROCEDURE IN EXAMINING HAMS. - -The hams were sectioned through the body, the femur, or “middle bone,” -as it is known in packing-house parlance, being cut at a point about -1½ or 2 inches below its head. A cross section of a ham thus cut -is shown in figure 1. After sectioning, the hams were subjected to a -microscopical, bacteriological, and chemical examination as follows: - -_Microscopical examination._—Bits of muscular tissue, taken from -various points, were teased out in salt solution and the condition of -the muscle fibers noted. Smear preparations were also made from bits -of muscular tissue and from the bone marrow, and these were stained -and subjected to microscopical examination. Portions of the meat were -also hardened and cut into microscopic sections, which were stained and -mounted for histological and bacteriological study. - -_Bacteriological examination._—In the bacteriological examination -of sour hams, especial attention was directed to the detection of -anaerobic species, as it seemed reasonable to suppose that if the -changes taking place in sour hams were due to bacteria these bacteria -would in all likelihood be anaerobes (i. e., organisms which develop -in the absence of oxygen). This assumption was based upon the fact -that, as a rule, souring begins in the interior of the ham next to the -bone, and, furthermore, the hams are cured in large vats where they -are completely submerged in the pickling fluids, so that any bacteria -which develop within the bodies of the hams while they are in cure are -probably restricted to practically anaerobic conditions. - -Cultures were made from the interiors of the hams at various points by -first searing the cut surface thoroughly with a heavy metal spatula and -then cutting out, by means of sterile scissors and forceps, plugs of -meat about 1 cm. square. The plugs of meat were then dropped into tubes -containing the egg-pork medium and pushed down to the bottom of the -tubes, where they were held in place by the chopped meat above; in this -way conditions favorable for the development of anaerobic organisms -were obtained. In inoculating the pork-agar tubes, the medium was -first boiled to expel any inclosed air and cooled to 43° to 45° C; the -plugs of meat were then dropped into the tubes and the agar rapidly -solidified by plunging the tubes in cold water; in this way the bits of -meat were inclosed in the agar at the bottom of the tubes, affording -suitable conditions for anaerobic growth. Aerobic and anaerobic plates -were also made from the meat, and in most cases bouillon tubes were -also inoculated. Cultures were always taken from the bone marrow as -well as from the meat. Novy jars were also used for obtaining anaerobic -conditions in growing the cultures. - -_Chemical examination._—In order to determine whether the souring was -connected with or dependent upon a lack of penetration of the pickling -fluids to the interior of the meat, the hams were further subjected to -a chemical examination and the content of the meat in sodium chlorid -and potassium nitrate determined at varying depths. - - - RESULTS OF EXAMINATION OF SOUR AND SOUND HAMS. - -The sour hams examined were obtained from four different packing -establishments. All of the hams studied were “sweet-pickle hams” which -had not been smoked. The sour hams selected for examination were good -typical body sours, in which the sour odor was well developed, but not -of the very pronounced or putrefactive type. - -The sour odor in every case was found to be more pronounced next to -the bone, being usually rather more pronounced just behind the bone, -that is, on the fat side of the bone. The sour odor in each instance -was confined to an area of meat immediately surrounding the femur and -extending out through the body of the ham for a variable distance, as -shown by the dotted lines in figure 1, but in no case did the sour odor -extend all the way to the margin of the meat, nor did it as a rule -extend below the tibio-femoral articulation, the shank proper and the -bone marrow of the shank (i. e., of the tibia) being usually sweet. The -butt portion of the hams—that portion above and behind the hitch bone -(symphasis pubis)—was also sweet. - -Immediately after sectioning, the sour areas, as a rule, could be -readily distinguished by a difference in color. In the freshly cut -hams the muscular tissue near the bone, where the sour odor was more -pronounced, exhibited a slight but distinct grayish hue, at times -having a slight greenish tinge; in other words, the muscular tissue in -the sour areas lacked the normal bright red color of the sound meat -and was distinctly lighter in color than the surrounding tissues. -Upon exposure to air, however, the lighter, grayish, sour areas tend -to assume a reddish hue and become much less pronounced than in the -freshly cut ham. After the cut surface of the ham has been exposed to -the air for some time it may be difficult to distinguish the sour areas -by any difference in color. - -[Illustration: - -BUL. 132, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. - PLATE I. - - FIG. 1.—SECTION OF MUSCULAR TISSUE FROM SOUND HAM, SHOWING - MUSCLE FIBERS CUT LONGITUDINALLY; NUCLEI SHARPLY DEFINED AND - CROSS STRIATION DISTINCT. - -(Pen-and-ink drawing made with camera lucida from section stained with - hematoxylin and eosin to show histological structure. × 320.)] - - - FIG. 2.—SECTION OF MUSCULAR TISSUE FROM SOUR HAM, SHOWING - MUSCLE FIBERS CUT LONGITUDINALLY; NUCLEI UNDERGOING - DISINTEGRATION AND CROSS STRIATION INDISTINCT. - -(Pen-and-ink drawing made with camera lucida from section stained with - hematoxylin and eosin to show histological structure. × 320.)] - -[Illustration: - - BUL. 132, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. - PLATE II. - - FIG. 1.—SECTION THROUGH MUSCULAR TISSUE OF HAM WHICH HAS - UNDERGONE NATURAL OR SPONTANEOUS SOURING, SHOWING DISTRIBUTION - OF BACILLI BETWEEN THE MUSCLE FIBERS, WHICH ARE CUT OBLIQUELY. - THE DARK MASSES BETWEEN THE MUSCLE FIBERS REPRESENT CLUMPS OF - BACILLI. - - (Pen-and-ink drawing made with camera lucida from section stained by - the Gram-Weigert method to show bacteria. × 85.) - - - FIG. 2.—SECTION THROUGH MUSCULAR TISSUE OF HAM WHICH HAS - UNDERGONE NATURAL OR SPONTANEOUS SOURING, SHOWING INDIVIDUAL - BACILLI BETWEEN THE MUSCLE FIBERS, WHICH ARE CUT SOMEWHAT - OBLIQUELY. NUCLEI HAVE LOST SHARP OUTLINE AND CROSS STRIATION - IS INDISTINCT. - -(Pen-and-ink drawing made with camera lucida from section stained by the - Gram-Weigert method to show bacteria. × 320.)] - -In the sour areas near the bone the muscular tissue was distinctly -softer; that is, it broke and cut more readily than the surrounding -tissues. This was usually quite noticeable in cutting out plugs of the -meat for making cultures. In a ham which shows pronounced souring the -muscular tissues in the worst affected areas may become quite soft and -even slightly gelatinous. - -The sour areas, when tested with litmus paper, frequently showed a -slight but distinct alkaline reaction. When aqueous extracts of the -sour meat, however, were titrated with phenolphthalein they were found -to be acid. - - - HISTOLOGICAL CHANGES IN SOUR HAMS. - -In preparations made by teasing out bits of the meat in physiological -salt solution, the cross striation of the muscle fibers from the sour -areas was found to be much less distinct than in similar preparations -taken from sound portions of the meat or from sound hams. At times it -was found that the muscle fibers in the sour areas had completely lost -their cross striæ, but the longitudinal striation could still be made -out. In cases where the souring was pronounced there was sometimes -complete loss of both longitudinal and cross striation; in these cases -the muscle fibers appeared to have undergone slight swelling and the -protoplasm exhibited a finely granular appearance. - -In stained sections of the sour meat another striking change was -noticed in the disintegration of the nuclei of the muscle fibers, which -are at times completely broken up, appearing as bluish granular masses -in sections stained with hematoxylin and eosin. (Compare figs. 1 and 2 -of Pl. I.) - -In sections stained by the Gram-Weigert method to show the presence of -bacteria, a large Gram-staining bacillus was noted between the muscle -fibers in the connective-tissue elements of the muscle. In some of the -sections these bacilli were present in great numbers, sometimes in -densely packed clumps or masses, while in other sections, or in other -portions of the same section, they were only sparsely distributed -between the muscle fibers. Where the bacteria were more numerous the -histological changes in the muscle fibers, especially the breaking -down of the nuclei, were more noticeable. The intermuscular connective -tissue had apparently furnished paths of least resistance along which -the organism followed. In Plate II, figures 1 and 2, the bacteria are -shown between the muscle fibers under low and high power magnifications. - -In Plate II, figure 1, under the low-power magnification, the bacteria -appear as dark clumps or bands between the muscle bundles. Under the -high power they are shown following along the sarcolemma sheaths -between the muscle fibers. - - - CHEMICAL ANALYSES OF SOUR AND SOUND HAMS. - -In order to determine whether there was any difference in regard to the -penetration of the pickling fluids in the sour hams as compared with -sound hams, a series of four sour hams were subjected to a chemical -examination in comparison with four sound hams. All were sweet-pickle -hams and were obtained from the same packing establishment. They were -all of the same cure and the same approximate age (i. e., length of -cure) and the same approximate weight. - -In taking samples for chemical analysis, the following procedure was -adopted: A section about 2½ inches wide was cut from the center of -the body. The two ends of this section were then trimmed off along -the lines L-M and N-O, as shown in figure 2. Beginning at the skinned -surface, four slices, A, B, C, and D, were then made, as indicated by -the dotted lines. Slice B contained the bone in each instance. Slice -D was practically all fat. Each slice was ground separately in a meat -chopper and the sample thoroughly mixed before taking out portions for -analysis. - -[Illustration: FIG. 2.—Cross section through body of ham to show method -of sampling for chemical analysis. A, slice below bone; B, bone slice; -C, slice above bone; D, fat slice.] - -As all of the hams examined were mild-cure hams, that is, had been -pumped in the shank only, the pickling fluids in order to reach the -bodies of these hams had to penetrate chiefly from the skinned surface -of the ham, as little if any penetration takes place through the thick -skin of the ham. - -The analyses[3] shown in the following tables therefore indicate the -degree of penetration of the pickling fluids. - -[3] These analyses were made by Mr. R. R. Henley, of the Biochemic -Division, Bureau of Animal Industry. - - _Analyses of sour hams._ - ───┬────────────┬──────┬───────────┬─────────── - No.│Description.│Slice.│ NaCl. │ KNO₃. - ───┼────────────┼──────┼───────────┼─────────── - │ │ │_Per cent._│_Per cent._ - 1 │Sour body │ A │ 6.18 │ 0.175 - │ │ B │ 4.83 │ .224 - │ │ C │ 3.65 │ .299 - │ │ D │ 1.03 │ .074 - │ │ │ │ - 2 │ do │ A │ 5.34 │ .174 - │ │ B │ 3.70 │ .150 - │ │ C │ 2.79 │ .174 - │ │ D │ 1.12 │ .012 - │ │ │ │ - 3 │ do │ A │ 5.04 │ .125 - │ │ B │ 4.08 │ .149 - │ │ C │ 2.72 │ .099 - │ │ D │ 1.19 │ .048 - │ │ │ │ - 4 │ do │ A │ 7.78 │ .250 - │ │ B │ 5.31 │ .100 - │ │ C │ 4.76 │ .200 - │ │ D │ 1.96 │ .048 - ───┴────────────┴──────┴───────────┴─────────── - - - _Analyses of sound hams._ - ───┬────────────┬──────┬───────────┬─────────── - No.│Description.│Slice.│ NaCl. │ KNO₃. - ───┼────────────┼──────┼───────────┼─────────── - │ │ │_Per cent._│_Per cent._ - 1 │Sound │ A │ 5.80 │ 0.211 - │ │ B │ 4.83 │ .188 - │ │ C │ 3.86 │ .221 - │ │ D │ 1.33 │ .063 - │ │ │ │ - 2 │ do │ A │ 4.94 │ .197 - │ │ B │ 4.08 │ .149 - │ │ C │ 3.05 │ .223 - │ │ D │ 1.56 │ .059 - │ │ │ │ - 3 │ do │ A │ 5.92 │ .173 - │ │ B │ 4.29 │ .099 - │ │ C │ 4.12 │ .139 - │ │ D │ 2.32 │ .049 - │ │ │ │ - 4 │ do │ A │ 5.53 │ .119 - │ │ B │ 4.89 │ .079 - │ │ C │ 4.32 │ .099 - │ │ D │ 2.19 │ .041 - ───┴────────────┴──────┴───────────┴─────────── - -Taking an average of the four slices in each ham so as to get an -average for the entire ham, and comparing the sour hams with the sound -hams, we have the following comparison: - - NaCl. KNO₃. - Average for 4 sour hams (entire ham) per cent. 3.84 0.143 - Average for 4 sound hams (entire ham) do 3.93 .131 - -These figures show practically no difference between the sour and the -sound hams as regards the sodium chlorid and potassium nitrate content -of the entire ham. - -If, now, we compare the bone slices—and these afford really a better -basis for comparison, as in sour-body hams the souring is always more -pronounced around the bone—we have the following figures: - - NaCl. KNO₃. - Average for 4 sour hams (bone slice) per cent. 4.48 0.155 - Average for 4 sound hams (bone slice) do 4.52 0.129 - -Here, again, we find no essential difference between the sour and the -sound hams, and we must conclude from these analyses that souring does -not depend upon or result from a lack of penetration of the pickling -fluids. - -It seems probable that in mild-cure hams, which are pumped in the -shank only, the souring begins in the upper portion of the shank and -extends upward along the bone into the body of the ham, and that it -takes place before the pickling fluid has penetrated to the interior -of the ham. When the pickling fluid reaches the interior of the ham -it tends to inhibit the souring, which, as will be shown later, is -due to the development of bacteria within the bodies of the hams. The -growth of the bacteria, however, within the bodies of the hams and the -histological changes in the muscle fibers do not seem to interfere with -the penetration of the pickling fluids. - - - BACTERIOLOGICAL EXAMINATION OF SOUR AND SOUND HAMS. - -In all of the sour hams which were examined bacteriologically a large -anaerobic bacillus was found to be constantly present. From several -of the hams this bacillus was obtained in pure culture; that is, it -was the only organism present in cultures made from the sour meat and -from the bone marrow of the femur. Such cultures, when held at room -temperature, gave, at three days, a sour-meat odor exactly resembling -that obtained from sour hams. - -In many of the sour hams other bacteria were found in association with -the anaerobic bacillus noted above. These other bacteria, however, were -not constant, being sometimes present and sometimes absent. Among the -other bacteria noted in the sour hams, the following forms occurred -most frequently: - -1. A nonmotile, gram-positive bacillus, measuring from 1.5 to 4 microns -in length by 0.5 micron in breadth, sometimes in chains and filaments. - -2. A small, nonmotile, gram-negative bacillus, about the size of -_Bacillus coli_ and usually in pairs. - -3. A large micrococcus. - -Sometimes one and sometimes all of these bacteria were present in a -given ham. They were encountered most frequently in hams which had -been pumped in both body and shank, and were probably ordinary pickle -bacteria. They were not strict anaerobes, but belonged to the class of -facultative or optional anaerobes; that is, organisms which will grow -either with or without free oxygen. These bacteria were isolated and -grown on the egg-pork medium, but failed to give any characteristic -sour or putrefactive odors, and were therefore discarded. - -A series of sound hams, all of them of mild cure—that is, hams which -had been pumped in the shank only—were also examined bacteriologically. -In examining these hams cultures were taken at varying depths, -beginning at the skinned surface and going backward toward the fat. -Cultures were also taken from the bone marrow of the femur. In the -cultures taken near the skinned surfaces the ordinary pickle bacteria -were obtained, but these did not, as a rule, extend beyond a depth of -3 centimeters below the skinned surface. The cultures taken from the -deeper portions of the hams and from the bone marrow of the femur were -entirely negative—that is, failed to show any growth—and the anaerobic -bacillus noted in the sour hams was not encountered in any of the -cultures made from these hams. - -The anaerobic bacillus isolated from the sour hams was found to -correspond in morphology with the organism noted in the microscopic -sections made from the muscular tissue. In view of this fact and the -fact that it was constantly present in the sour hams examined, and was -capable of producing in egg-pork cultures a sour-meat odor of the same -nature as that obtained from sour hams, this organism was subjected to -further study and experimentation. - - - INOCULATION EXPERIMENTS WITH HAMS. - -The experiments which follow were conducted at two different packing -establishments in one of the larger packing centers of the country. -The officials at each of these establishments showed great interest in -the experiments and were most courteous and obliging in supplying the -necessary materials. - -The first question to be decided was whether the bacillus isolated from -sour hams was actually capable of causing ham souring. The bacillus in -question had, when cultivated on the egg-pork medium, given rise to a -sour odor similar to that obtained from sour hams, but this was not -regarded as proof positive that the organism was the actual cause of -souring in hams. The proper way to decide this point seemed to be to -inoculate hams with the bacillus and then subject these hams to the -regular method of cure and see whether they became sour, just as the -pathogenic properties of a disease-producing organism are determined by -the inoculation of experiment animals. The first two experiments which -follow were designed to decide this point. - -It was regarded as important to conduct similar experiments at two -different establishments, in order to determine whether the same -results would be obtained under the somewhat different conditions -imposed by different methods of cure. The two experiments which follow -were carried out, therefore, at different establishments. - - - _Experiment I._ - -In carrying out this experiment four tierces of hams were “put down” -or “packed”—that is, placed in cure. Two of the tierces were given the -fancy or mild cure and two the regular or stronger cure. The hams in -two of the tierces, one mild and one regular cure, were injected with -a culture suspension of the bacillus; the other two tierces were not -injected with culture and were put down to serve as checks on the -cure. Hams weighing from 12 to 14 pounds were used for the mild cure, -while for the regular cure hams weighing from 14 to 16 pounds were -used. This was in accordance with the general rule which prevails in -packing houses, the lighter hams being subjected to the mild cure and -the heavier hams to the regular cure. The only difference between the -mild and the regular cure in this experiment lay in the pumping. The -hams which were given the mild cure were pumped in the shank only, -while those given the regular cure were pumped in the body as well as -in the shank. - -All of the hams had received the usual 48-hour chill. They were all -pumped with the same pumping pickle and cured in the same curing -pickle, and were in cure for the same length of time. The pumping and -curing pickles used were the regular pumping and curing pickles of the -establishment at which the experiment was carried out, and the hams -were cured in accordance with the fancy and regular cures as practiced -at this establishment. - -The hams were packed in new tierces which had been thoroughly scalded -with boiling water. The tierces were held in a curing room which was -kept at an average temperature of from 34° to 36° F., the temperature -occasionally going as high as 38° and 40° F., but never above 40° -F. The hams were left in cure for about 70 days, which is a little -longer than the usual cure. The tierces were rolled three times during -the cure. At the end of the cure the hams in all four tierces were -carefully tested by an expert meat inspector, who knew nothing of the -treatment which the hams had received. - -The hams in two of the tierces were inoculated with a culture -suspension prepared as follows: Ten tubes of egg-pork medium, each -tube containing approximately 10 cubic centimeters of the medium, -were inoculated with the bacillus and held at room temperature (20° -to 25° C.) for six days. The cultures were then filtered through -sterile gauze into a large sterile flask; this was done in order to -remove the particles of meat, which might otherwise have clogged the -syringes used in inoculating the hams. In transferring the contents -of the culture tubes to the filter the tubes were washed out with -sterile physiological salt solution (0.6 per cent sodium chlorid), -and the meat particles on the filter were afterwards washed with the -salt solution, a sufficient quantity of the latter being used to bring -the total volume of filtrate to 400 cubic centimeters. A microscopic -preparation from the filtrate showed the organisms in large numbers, -with an occasional rod showing a large terminal spore. This suspension -was used for the injection of 40 hams, each ham being given 10 cubic -centimeters, or the equivalent of 2.5 cubic centimeters of the original -culture. The hams were injected with the culture suspension by means of -a sterile syringe carrying a long 5-inch needle. The needle was thrust -well into the body of the ham at a point near the upper end of the -middle bone or femur, the latter being used as a guide in inserting -the needle and the injection being made into the tissues just behind -and a little to one side of the upper end of the femur. - -The details of the experiment were as follows: - - _Tierce No. 1 (fancy cure)._—This tierce contained 20 hams - weighing from 12 to 14 pounds each. These hams were pumped in - the shank only. Immediately after pumping they were injected - with 10 cubic centimeters each of the liquid culture or - suspension described above. After injection the hams were - immediately packed in the tierce, which was then headed up, - filled with the regular curing pickle, and placed in cure. - - Result: When tested at the end of the cure all of the hams - in this tierce save one were found to be sour. In 10 of them - the souring was very marked throughout the body of the ham - and extended into the shank as well. In six the souring was - very marked in the body of the ham, but did not extend into - the shank. In three there was slight but well-marked souring - in the body of the ham with no souring in the shank, and one - remained sweet. The probable explanation of the variation in - the degree and the extent of the souring will be discussed - later. The bone marrow of the femur or middle bone was tested - in all of the hams and found to be sour in 18. In one of the - hams which showed only slight souring in the body the souring - did not extend through to the bone marrow, and in the ham which - remained sweet the bone marrow was also sweet. The fact that - one ham in this tierce remained sweet was in all likelihood - due to an oversight in making the inoculations. In making the - inoculations the hams were spread out in a row on a table by a - packing-house assistant, who removed the hams as soon as they - were inoculated and placed them in tierces; and it is more than - probable that the assistant removed one of the hams before it - was inoculated in the interval when the writer was busy filling - the syringe for the next inoculation. - - _Tierce No. 2 (fancy cure)._—This tierce contained 20 hams of - the same average weight as the preceding. They were pumped in - the shank only, but were not injected with culture, being put - down to serve as checks on the hams in tierce No. 1. These - hams, therefore, were subjected to exactly the same cure and - were held under exactly the same conditions as those in tierce - No. 1, the only difference being that the hams in this tierce - were not injected with culture. - - Result: When tested at the end of the cure all of the hams in - this tierce were found to be perfectly sound and sweet, showing - that the curing in this instance was properly carried out and - that the souring of the hams in tierce No. 1 was undoubtedly - due to the injections of culture which they received. - - _Tierce No. 3 (regular cure)._—This tierce contained 20 hams - weighing from 14 to 16 pounds each. These hams were pumped in - the shank and also in the body. Immediately after pumping they - were each injected in the same manner as those in tierce No. 1 - with 10 cubic centimeters of culture. The hams were then packed - in tierce and placed in cure. - - Result: At the end of the cure 9 of the hams were found to be - sour, while 11 remained sweet. Of the 9 hams which became sour, - 1 showed very pronounced souring in the body and in the shank - as well, 3 showed very pronounced souring in the body, 1 showed - pronounced souring in the body, and 4 slight souring in the - body. The bone marrow of the femur was tested in all of the - sour hams and was found to be sour in 7. In 2 of the sour hams - which showed slight souring in the body the souring noted in - the meat had not extended through to the bone marrow. - - _Tierce No. 4 (regular cure)._—This tierce contained 20 hams - of the same average weight as those in tierce No. 3, and, like - the latter, were pumped in both shank and body, but were not - injected with culture. This tierce was put down to serve as - a check on tierce No. 3 and was held under exactly the same - conditions, the only difference being that these hams were not - injected with culture. - - Result: At the end of the cure the hams were carefully tested - and all were found to be perfectly sound and sweet. - - - _Results of Experiment I._ - - ───────┬────────┬─────────┬────────┬───────────── - No. of │ Number │ Average │ Cure. │ How pumped. - tierce.│of hams.│ weight │ │ - │ │ of hams.│ │ - │ │ │ │ - ───────┼────────┼─────────┼────────┼───────────── - │ │_Pounds._│ │ - 1 │ 20 │ 12-14 │ Fancy │Shank only - │ │ │ │ - │ │ │ │ - 2 │ 20 │ 12-14 │ do │ do - │ │ │ │ - │ │ │ │ - 3 │ 20 │ 14-16 │Regular │Shank and body - │ │ │ │ - │ │ │ │ - 4 │ 20 │ 14-16 │ do │ do - │ │ │ │ - ───────┴────────┴─────────┴────────┴───────────── - - ───────┬─────────────────┬───────────────────────── - │ │ Condition at end - │ │ of cure - │ ├───────────┬───────────── - No. of │ Treatment │ Number of │Percentage of - tierce.│ │ sour hams │ sour hams - ───────┼─────────────────┼───────────┼───────────── - 1 │Each ham injected│ 19 │ 95 - │with 10 c.c. of │ │ - │culture. │ │ - │ │ │ - 2 │Not injected with│ 0 │ 0 - │culture; check on│ │ - │tierce 1. │ │ - │ │ │ - 3 │Each ham injected│ 9 │ 45 - │with 10 c.c. of │ │ - │culture. │ │ - │ │ │ - 4 │Not injected with│ 0 │ 0 - │culture; check on│ │ - │tierce 3. │ │ - ───────┴─────────────────┴───────────┴───────────── - -Three hams from each tierce were selected for bacteriological and -histological examination. From tierces 1 and 3, which contained the -injected hams, three of the most pronounced “sours” were selected from -each tierce. In examining the hams bacteriologically the following -method was adopted: The hams were sectioned near the center of the body -and the larger or butt end turned up so as to expose the cut surface. A -cross section of a ham thus cut is shown in figure 3. - -Cultures were taken at the points indicated by the numbers and from the -exposed bone marrow of the femur by first searing the surface, and then -taking out plugs of the meat or marrow by means of sterile instruments. -The plugs of meat or marrow were dropped into tubes containing egg-pork -medium and pushed to the bottom of the tubes by means of a sterile -platinum wire. In the cultures made from the sour hams from tierces 1 -and 3, which were injected with culture, the bacillus with which these -hams were injected was found in practically every culture, although it -was sometimes absent in the cultures taken at points near the skinned -surfaces of the hams (i. e., at points 1, 4, and 5 in fig. 3). In the -cultures taken from the meat, the bacillus was not always present in -pure culture, but this is not to be wondered at when we remember that -the pickling fluids often contain large numbers of bacteria of various -kinds, and these, of course, find their way into the hams in the -pickling fluids. Especially is this true of the hams which are pumped -in the body, where bacteria are actually pumped into the bodies of the -hams in the pumping pickle. In the case of hams which are not pumped in -the body, the pickle bacteria do not appear to penetrate the body of -the ham to any great depth. - -In figure 3 the plus signs after the figures represent the distribution -of the sour-ham bacillus in one of the hams from tierce 1, and this -may be taken as a typical example of the other sour hams which were -examined in this experiment. It should be explained that the shaded -areas are not intended to represent the actual limits of souring, but -simply the areas in which the sour odor was most pronounced and from -which it could be readily obtained with the trier. In comparing the -regular and mild cure hams, it was found that the areas of souring as -defined with the trier were more restricted in the regular cure hams, -and this was undoubtedly due to the additional pumping which these hams -received, whereby the growth of the bacillus was partially inhibited. - -[Illustration: - - FIG. 3.—Cross section through body of artificially soured ham, - showing sour areas and points at which cultures were taken. - Darker shading indicates sour area in hams pumped in body and - shank; light shading indicates sour area in hams pumped in - shank only; figures indicate points at which cultures were - taken; plus signs indicate presence of bacillus; minus sign - indicates absence of bacillus; X indicates point of inoculation.] - -It will be noticed that the sour-ham bacillus was present in cultures -taken at points outside the shaded areas, indicating that the organism -had extended generally throughout the bodies of the hams. As the -hams were inoculated at a point just to one side of and a little -behind the femur (i. e., at the point X in the figure), the presence -of the bacillus generally throughout the hams would indicate a very -extensive multiplication of the original bacilli with which the hams -were injected. In view of the fact that the bacillus in question is -nonmotile, the spread of the bacilli throughout the hams must result -simply from subdivision and growth by extension, and in spreading -throughout the hams the bacilli appear to follow along the connective -tissue bands which afford paths of least resistance. In the cultures -made from the bone marrow the bacillus was recovered in pure culture -from each of the hams examined, and it is probable that the bacillus -finds its way into the bone marrow from the meat by following along the -small arteries which pass through the bone. The fact that the bacillus -was found in pure culture (i. e., uncontaminated) in the cultures -made from the bone marrow is explained probably by its capacity for -growth by extension, and also by the fact that the pickling solutions -probably do not reach the bone marrow until late in the curing and -then only to a limited extent. The bacteria which ordinarily occur in -pickling fluids are not strict anaerobes and are not placed under the -most suitable conditions for growth when they reach the interior of -the ham, for it seems probable that in the interior of hams which are -totally submerged in pickling fluids the amount of available oxygen -must be extremely small. The ordinary pickle bacteria, therefore, would -not multiply as rapidly in the interior of the hams and would not find -their way into the bone marrow as soon as would a strictly anaerobic -organism. - -Pure cultures of the sour-ham bacillus, recovered from the meat and -bone marrow of the injected hams, were compared with cultures of the -original bacillus used for inoculating the hams, and were found to be -identical. Furthermore, the bacillus with which the hams were injected -was recovered from the injected hams at points far removed from the -original point of injection, showing that the organism had multiplied -and extended throughout the bodies of the hams and that it was clearly -responsible for the souring which the hams had undergone. - -Sound hams from tierces 2 and 4 were examined bacteriologically in the -same manner as the injected hams, and some of the cultures showed the -ordinary pickle bacteria, but in not a single instance did egg-pork -cultures yield a sour odor, and in no case could the sour-ham bacillus -be demonstrated in any of these hams. - -Microscopic sections and teased preparations of the muscle fibers in -salt solution were prepared from several of the sour hams in this -experiment, and these preparations showed the same histological changes -and the same distribution of bacilli as noted in the natural sours. - -In Plate III, figures 1 and 2, sections are shown of artificially -soured hams, that is, hams which were artificially soured by injections -of culture; and if these figures be compared with the sections made -from hams which had undergone spontaneous souring (see Pl. II, figs. 1 -and 2) the similarity in the form and distribution of the bacilli will -be at once apparent. - - -[Illustration: - - BUL. 132, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. - PLATE III. - - FIG. 1.—SECTION THROUGH MUSCULAR TISSUE OF ARTIFICIALLY SOURED - HAM, SHOWING DISTRIBUTION OF BACILLI BETWEEN THE MUSCLE FIBERS, - WHICH ARE SHOWN IN CROSS SECTION. THE DARK LINES AND MASSES - BETWEEN THE MUSCLE FIBERS REPRESENT CLUMPS OF BACILLI. - - (Pen-and-ink drawing made with camera lucida from section stained by - the Gram-Weigert method to show bacteria. × 85.)] - - FIG. 2.—SECTION THROUGH MUSCULAR TISSUE OF ARTIFICIALLY SOURED - HAM, SHOWING INDIVIDUAL BACILLI BETWEEN THE MUSCLE FIBERS, - WHICH ARE CUT LONGITUDINALLY. - - (Pen-and-ink drawing made with camera lucida from section stained by - the Gram-Weigert method to show bacteria. × 320.)] - -_Summary and discussion of Experiment I._—Comparing tierces 1 and 2, -where the hams were pumped in the shank only, the only difference being -that the hams in tierce 1 were inoculated with culture while those in -tierce 2 were not, we find that in tierce 1 nineteen out of twenty, or -95 per cent, of the hams became sour, whereas in tierce 2 all of the -hams remained sweet. In view of the fact that these tierces were held -under exactly the same conditions, we must conclude that the souring -of the hams in tierce 1 was due to the injection of culture which they -received. - -Comparing tierces 3 and 4, where the hams were pumped in both shank and -body, the hams in tierce 3 being injected with culture while those in -tierce 4 were not, we find that in tierce 3 nine out of twenty, or 45 -per cent, of the hams became sour, whereas in tierce 4 all of the hams -remained sweet. As the conditions of cure were the same for all four -tierces, we must again conclude that the souring of the hams in tierce -3 was directly attributable to the injections of culture which they -received. - -If now we compare tierces 1 and 3, the two tierces which were injected -with culture, we find that in the case of tierce 1, where the hams were -pumped in the shank only, 95 per cent became sour; whereas in the case -of tierce 3, where the hams were pumped in both shank and body, only -45 per cent became sour. In other words, the percentage of souring in -those hams which were pumped in the body as well as in the shank was 50 -percent less than in those hams which were pumped in the shank only. -Inasmuch as the only difference in the treatment accorded tierces 1 -and 3 lay in the additional pumping given the hams in tierce 3, we -must conclude that the marked diminution in the percentage of souring -in the case of tierce 3 was undoubtedly due to the additional pumping -which these hams received, the hams being saturated at the start with -the pumping pickle. It will be shown later that both sodium chlorid and -potassium nitrate exert an inhibitory effect upon the bacillus with -which the hams were injected, which directly bears out the foregoing -conclusion. - -In tierces 2 and 4, the two check tierces which were not injected with -culture, all of the hams were sweet at the end of the cure, showing -that the conditions under which the experiment was carried out were -entirely favorable to a successful cure. - -The sour odor obtained from the artificially soured hams in this -experiment was pronounced by the meat inspector who tested the hams, -and who was entirely unaware of the treatment they had received, to be -identical with the usual sour odor which characterizes hams that have -undergone spontaneous souring; in other words, there was no difference -in odor between these artificially soured hams and natural sours. - -With regard to the variation in the degree and the extent of the -souring exhibited by the individual hams in the two inoculated tierces, -where some of the hams showed pronounced souring throughout the body -and shank, while others which had been injected with the same amount of -culture showed only slight souring in the body, several factors must -be considered, viz: (1) Differences in the reaction of the meat of the -individual hams which may have exerted an influence on the growth of -the bacteria with which the hams were injected. (2) Variations in the -texture of the muscle fibers and connective tissue of the individual -hams, permitting in some cases a more rapid and thorough penetration of -the pickling fluids to the interior of the hams, whereby the inhibitory -effect of the sodium chlorid and the potassium nitrate on the bacteria -would come into play earlier. (3) Variations in pumping, whereby more -of the pickling solution was forced into some of the hams than into -others. Probably all three of these factors would have to be taken into -account in explaining the variation in the degree and extent of the -souring exhibited by the injected hams. - -With regard to the souring of the bone marrow, we find that of nineteen -sour hams in tierce 1 eighteen showed sour marrows, while in tierce 3 -nine sour hams showed seven sour marrows. The high proportion of marrow -sours is not surprising when it is recalled that of the nineteen sour -hams in tierce 1 the meat was markedly sour in sixteen, while of the -nine sour hams in tierce 3 the meat was markedly sour in five. In the -case of the four sour hams in tierce 3 which showed slight souring in -the body, two of these showed sour marrows, while in two the marrows -were sweet. In this experiment the percentage of sour hams showing sour -marrows corresponds with the percentage of marrow-sour hams found in -the packing house, where, as has been pointed out before, a ham which -is markedly sour in the body will practically always show sour marrow, -while in hams which show only slight souring in the body the marrow is -involved in about 50 per cent of the cases. - - - _Experiment II._ - -This experiment was essentially a repetition of Experiment I, but was -carried out at a different packing establishment and under somewhat -different conditions. - -Two lots of hams were injected with a culture suspension of the -bacillus at different stages of the cure, or rather at different stages -in the preparation for cure, i. e., (1) on the hanging floor, previous -to chilling, and (2) after chilling and pumping and immediately before -packing. Three tierces, each containing 20 hams, were put down. Two of -the tierces contained the hams injected with culture, while the third -tierce contained check hams which had not been treated with culture. -Half of the hams in each tierce were pumped in the shank, while the -other half were pumped in both body and shank. The same pumping and -curing pickles were used for all three tierces, and were the regular -pumping and regular curing pickles of the establishment at which the -experiment was carried out. The hams used were all 14 to 16 pounds -in weight and were subjected to the usual 48-hour chill with an -additional chill of 48 hours after they were cut from the carcass. They -were packed in tierces which had been thoroughly scrubbed and cleaned -with boiling water. The tierces were held in a pickling room at a -temperature of 33° to 36° F., the temperature never rising above 36° -F., and were rolled three times during the curing period. The hams were -in cure for about eighty days. At the end of the cure the hams were -carefully tested by a trained meat inspector, who knew nothing of the -treatment they had received. - -The culture suspension was prepared from 20 tubes of egg-pork medium -in the same manner as that used in Experiment I, the cultures being -diluted with sufficient salt solution to give 400 cubic centimeters of -suspension. The cultures from which the suspension was prepared had -grown at room temperature for ten days. The suspension was examined -microscopically and showed large numbers of the bacilli in the form -of filaments or long chains, with many of the individual organisms -showing large terminal spores. The hams were injected with the culture -suspension in the same manner as those in Experiment I. - -The details of the experiment were as follows: - - _Tierce No. 1._—Contained 20 hams, each ham being injected - with 20 cubic centimeters of the suspension or the equivalent - of 10 cubic centimeters of the original culture. The hams were - injected while on the hanging floor, before they had been cut - from the carcasses and previous to chilling. The carcasses were - still quite warm—that is, had lost but little of their body - heat when the injections were made. The carcasses, which had - been carefully tagged, were then run into coolers and given the - usual 48-hour chill, after which the hams were severed from the - carcasses and given an additional 48-hour chill in accordance - with the custom of the packing house at which the experiment - was carried out. The hams were next pumped with regular pumping - pickle, 10 being pumped in both body and shank and 10 in shank - only. They were finally packed in a tierce, which was then - headed up, filled with regular curing pickle, and placed in - cure. - - Result: When tested at the end of the cure it was found that - the 10 hams which were pumped in the shank only were all sour. - In each of them the souring extended throughout the entire ham, - in the shank as well as in the body, and was very pronounced, - so much so that they were characterized as “stinkers” by the - meat inspector who assisted in testing them. The bone marrow - of the femur or middle bone was sour in all of these hams. Of - the 10 hams which were pumped in both body and shank 7 showed - well-marked souring throughout the body, but the souring did - not extend into the shank. The bone marrow of the femur was - found to be sour in 6 of these hams, while in 1 the souring had - not extended through to the bone marrow. - - _Tierce No. 2._—Contained 20 hams which were chilled and pumped - in exactly the same manner as those in tierce No. 1. These hams - were injected with culture after they had been chilled and - pumped, or just before they were placed in cure. The hams in - this tierce, therefore, were injected with culture four days - later than those in tierce 1. The hams were injected with a - bacterial suspension prepared in the same manner as that used - for tierce 1, except that the egg-pork cultures from which - the suspension was prepared were 7 days instead of 10 days - old. Each ham was injected with 20 cubic centimeters of the - suspension or the equivalent of 10 cubic centimeters of the - original culture. The hams were injected in the same manner as - those in tierce 1. - - Result: When tested at the end of the cure, it was found that - of the 10 hams which were pumped in the shank all were sour; in - 8 of these the souring was very marked throughout the body of - the ham and extended into the shank; in all of these hams the - souring had extended through to the bone marrow of the middle - bone or femur. Of the 10 hams which were pumped in both body - and shank 6 were sour in the body. These hams were classed by - the meat inspector who examined them as “light body sours,” - and in none of them did the souring extend into the shank or - through the bone into the bone marrow of the femur. - - _Tierce No. 3._—Contained 20 hams which were chilled and pumped - in the same manner as those in the two preceding tierces. These - hams were not injected with culture and were put down to serve - as checks on the cure. In other words, they were pumped with - the same pickling fluids, were subjected to exactly the same - cure, and were held under precisely the same conditions as - those in the preceding tierces, the only difference being that - the hams in this tierce were not injected with culture. - - Result: When tested at the end of the cure, all of the hams in - this tierce were found to be perfectly sound and sweet. - - - _Results of Experiment II._ - - ───────┬──────┬─────────┬────────────────────── - │ │ │ - No. of │Number│ Average │ How pumped. - tierce.│ of │ weight │ - │hams. │ of hams.│ - │ │ │ - ───────┼──────┼─────────┼────────────────────── - │ │_Pounds._│ - │ │ │{ 10 in shank - 1 │ 20 │ 14-16 │{ - │ │ │{ - │ │ │{ 10 in body and shank - │ │ │ - │ │ │{ 10 in shank - 2 │ 20 │ 14-16 │{ - │ │ │{ - │ │ │{ 10 in body and shank - │ │ │ - 3 │ 20 │ 14-16 │{ 10 in shank - │ │ │{ 10 in body and shank - ───────┴──────┴─────────┴─────────────────────── - ───────┬───────────────────────────┬─────────────────── - │ │Condition at end of - No. of │ Treatment. │ cure. - tierce.│ ├————————┬—————————— - │ │ Number │Percentage - │ │of sour │ of sour - │ │ hams. │ hams. - ───────┼───────────────────────────┼────────┼─────────── - │ │ │ - │Each ham injected with 20 │ 10 │ 100 - 1 │c. c. of culture prior to │ │ - │chilling and pumping. │ │ - │ do │ 7 │ 70 - │ │ │ - │Each ham injected with 20 │ 10 │ 100 - 2 │c. c. of culture subsequent│ │ - │to chilling and pumping. │ │ - │ do │ 6 │ 60 - │ │ │ - 3 │Not injected with culture. │ 0 │ 0 - │ do │ 0 │ 0 - ───────┴───────────────────────────┴────────┴────────── - -Four hams were selected from each tierce for bacteriological and -histological examination. From tierces 1 and 2, in which the hams -were injected with culture, 4 of the sourest hams were selected from -each tierce. Cultures were made from these hams in the same manner -as described under Experiment I and with the same result—that is, -the sour-ham bacillus was found throughout the bodies of the hams. -Microscopic sections were also prepared from these hams and showed the -same histological changes and the same distribution of bacilli as noted -for the hams in Experiment I. - -_Summary and discussion of Experiment II._—Comparing tierces 1 and 2, -in which the hams were injected with culture, with tierce 3, where the -hams were not injected with culture, we find that in tierce 1 seventeen -hams (85 per cent) became sour and in tierce 2 sixteen hams (80 per -cent) became sour, whereas in tierce 3 all of the hams were sweet. The -fact that all of the hams in tierce 3, the check tierce, were sweet -indicates that the conditions were favorable for a successful cure; and -as all three tierces were cured under exactly the same conditions, the -only difference being that the hams in tierces 1 and 2 were injected -with culture, whereas those in tierce 3 were not injected with culture, -we must conclude that the souring of the hams in tierces 1 and 2 was -due to the injections of culture which they received. - -Comparing tierce 1 with tierce 2, we find that the hams in tierce 1 -showed more extensive souring than did those in tierce 2, this being -especially noticeable in the case of the hams which were pumped in both -body and shank. This difference in the extent or degree of souring was -probably due to the fact that the hams in tierce 1 were injected while -they were still warm and before they had lost their animal heat, the -bacterial suspension thus having a better chance to become disseminated -through the meat. The hams in tierce 2 were injected with culture after -they had been chilled, when the tissues were more or less contracted -and the conditions less favorable for the dissemination of the -suspension throughout the meat. The hams in tierce 1 were also injected -four days earlier than those in tierce 2, and prior to pumping; and -this would explain the greater difference in the extent of the souring -in the case of the hams which were pumped in both body and shank, as in -tierce 1 the bacteria had four days in which to develop before coming -in contact with the pickling fluids, whereas in tierce 2 the bacteria -were injected after the hams were pumped with pickle and were thus -brought into immediate contact with the pickling fluids, which, as will -be shown later, have a distinct inhibitory action upon the bacillus in -question. In the case of the hams which were pumped in the shank but -not in the body there was not this difference, as in these hams the -pickling fluids must penetrate into the bodies of the hams from the -outside. As it requires some time for the pickling fluids to reach the -interior of a ham, the bacteria were thus afforded quite an interval -in which to develop before being exposed to the inhibitory action of -the pickling fluids. A chemical study of the processes involved in -ham curing has been carried out in the Biochemic Division and the -approximate rate of penetration of the curing pickle determined, -and it was found that it required about four weeks for the interior -of a 10-pound ham which had not been pumped to acquire its maximum -percentage of sodium chlorid. - -To recapitulate: In this experiment 40 hams were injected with culture, -half of this number being pumped in the shank only and half in both -body and shank. Of the 20 which were pumped in the shank only, every -ham without exception, or 100 per cent, became sour. Of those which -were pumped in both body and shank, 13, or 65 per cent, became sour. -The reduction in the percentage of sours in the last lot was clearly -due to the additional pumping which these hams received. - -If now we compare tierce 2 in this experiment with tierces 1 and 3 in -Experiment I—these three tierces being comparable, as they were all -injected with culture at the same stage in their preparation for cure, -that is, subsequent to chilling and pumping—we find, in the case of the -hams pumped in both body and shank, 65 per cent of sours in Experiment -II as against 45 per cent in Experiment I, and this difference is -undoubtedly due to the heavier dose of culture used in Experiment -II, where the hams were given the equivalent of 10 cubic centimeters -of egg-pork culture as against 2½ cubic centimeters in Experiment -I. In the case of the hams which were pumped in the shank but not in -the body, the percentage of sours was practically the same in the two -experiments—in Experiment I all but one of these hams became sour, -while in Experiment II all of them became sour. The degree or extent of -the souring in these last hams, however, was greater in Experiment II, -a result of the heavier injections of culture which they received. - - - _Summary of Experiments I and II._ - -Summarizing the results obtained in Experiments I and II, we find that -culture suspensions of the anaerobic bacillus isolated from sour hams -caused souring with great uniformity when injected into the bodies of -sound hams which were pumped in the shank only. In the two experiments, -40 sound hams which were pumped in the shank only were injected with -culture suspensions of the bacillus, with the result that 39, or 97.5 -per cent, became sour during the process of cure; and it is quite -probable, as we have pointed out before, that one of these hams was -overlooked in making the inoculations, otherwise the entire lot would -have become sour. - -The inhibitory action of the pickling fluids upon the bacillus is well -shown in the case of those hams which were pumped in both body and -shank. Out of 40 hams which were pumped in both body and shank, 22, or -55 per cent, became sour in the process of curing. Inasmuch as these -hams were cured under precisely the same conditions as the hams which -were pumped in the shank only, we must conclude that the diminution in -souring in these hams was undoubtedly due to the additional pumping -which they received, whereby the bacteria with which these hams were -injected were brought into immediate contact with the strong pumping -pickle and their development thereby inhibited. - -In these two experiments it was proven beyond doubt that the anaerobic -bacillus isolated from sour hams was capable of producing souring -when introduced into the bodies of sound hams; and in view of the fact -that this bacillus was constantly present in hams which had undergone -spontaneous or natural souring, and was the only organism that could -be isolated from such hams that was capable of producing in egg-pork -cultures the characteristic sour-ham odor, the conclusion seems -justifiable that this bacillus is an undoubted cause of the ham souring -which occurs in the packing house; and the results thus far obtained -indicate that it is an important, if not the only, factor concerned in -ham souring. - -Having established the etiological relation of the bacillus isolated -from sour hams with ham souring, the next point to be considered was -the manner in which this bacillus finds its way into the bodies of the -hams. - - - PROBABLE METHOD BY WHICH HAM-SOURING BACILLUS ENTERS HAMS. - -Regarding the question of the probable method by which the ham-souring -bacillus enters hams, there were three possibilities to be taken into -consideration: (1) That the bacillus is present in the flesh of hogs at -the time of slaughter, (2) that the bacillus gains entrance through the -pickling fluids, (3) that the bacillus is introduced into the bodies -of the hams in the handling or manipulation which the hams undergo in -preparation for, or during, the process of curing. - - - POSSIBILITY OF INFECTION PRIOR TO SLAUGHTER. - -In order to throw some light upon this point, a number of fresh -hams—that is, hams which had been chilled but not pumped or subjected -to any other manipulation—were examined bacteriologically, but in no -case could the anaerobic bacillus which was isolated from sour hams -be detected in any of them. The fact that in certain of the smaller -packing establishments which cure their hams without pumping the -percentage of souring is extremely low would also seem to negative this -possibility, for if the bacillus which causes souring were present in -the hams at the time of slaughter, sour hams would be as frequent at -such establishments as at those establishments which make a practice of -pumping. Furthermore, a laboratory study, biological and chemical, of -the bacillus isolated from sour hams shows that this organism belongs -to the class of putrefactive bacteria, and while such bacteria may be -present in the intestines of healthy animals, as, for example, the -bacillus of Bienstock (_Bacillus putrificus_), these bacteria do not -invade the organs and tissues of the body until after the death of the -animal, and the packing-house practice of rapidly eviscerating the hogs -immediately after slaughter would certainly preclude this possibility. - - - POSSIBLE INFECTION FROM PICKLING FLUIDS. - -With regard to the second possibility, that the bacillus finds its way -into the hams in the curing pickles, it was determined by laboratory -experiment that the addition of 3 per cent of sodium chlorid or 3 per -cent of potassium nitrate to laboratory media completely inhibits -the growth of the bacillus. As the pickling solutions always contain -considerably more than these percentages of sodium chlorid and -potassium nitrate, it would be impossible for the bacillus to multiply -in the pickles. Additional laboratory experiments demonstrated, -however, that the bacillus or its spores may remain alive in the curing -pickles for at least thirty days, and it seemed possible that the -curing pickles might become contaminated at times with the bacilli, and -that the bacilli, although incapable of multiplying in the pickles, -might find their way into the bodies of the hams in the pickling -fluids. In order to throw some light upon this point, the following -experiment was carried out: - - -EXPERIMENT TO SHOW WHETHER INFECTION TAKES PLACE FROM THE CURING PICKLE. - -In this experiment two tierces were put down, each containing 20 hams. -The hams weighed from 14 to 16 pounds and had received the usual -48-hour chilling. The pickling solutions employed were the regular -curing pickles of the establishment at which the experiment was carried -out. The curing pickle in one tierce was inoculated with 400 cubic -centimeters of a culture suspension of the bacillus, prepared in the -same manner as that used for the injection of the hams in tierce 2 in -Experiment II. A microscopic preparation made from a small drop of the -culture suspension before adding it to the pickle showed the bacilli -in large numbers, and in the 400 cubic centimeters of the suspension -there were millions of the bacteria. The curing pickle in the other -tierce was left untreated, the hams in this tierce serving as a check. -The tierces used in this experiment, as in all of the experiments, were -thoroughly cleaned with boiling water before the hams were placed in -them. The experiment was conducted in a pickling room which was held at -33° to 36° F., and the tierces were rolled three times during the cure. -The details of the experiment are as follows: - - _Tierce 1._—Contained 20 hams, half of which were pumped in - both body and shank and half in the shank only. As soon as they - were pumped the hams were packed in the tierce. Sufficient - curing pickle to fill the tierce was then measured out in a - clean barrel and to it was added the culture suspension. The - culture was thoroughly mixed with the pickle and the latter was - then run into the tierce containing the hams. - - Result: When tested at the end of the cure, two of the hams - which had been pumped in the shank only showed slight souring - in the body. The rest of the hams were sweet. - - _Tierce 2._—Contained 20 hams which were pumped in the same - manner as those in tierce 1. The curing pickle was the same as - that used for tierce 1, but without the addition of culture. - This tierce was put down as a check on tierce 1, the hams - being cured under exactly the same conditions, but without the - addition of culture to the curing pickle. - - Result: One of the hams which was pumped in the shank only - developed slight souring in the body. The remainder of the hams - were sweet. - -Comparing tierce 1, which contained the inoculated pickle, with tierce -2, the check tierce which contained uninoculated pickle, we find -there was practically no difference in the final result. In tierce 1 -two of the hams developed slight souring, while in tierce 2 one of -the hams became slightly sour. All of these hams had been pumped in -the shank only. The fact that one of the hams in the check tierce -developed slight souring was undoubtedly due to bacterial contamination -in pumping or in the handling which the hams underwent prior to -pickling, and the slight souring of the two hams in tierce 1 must -also be attributed to the same cause or causes, for had the souring -in these last hams resulted from the penetration of the bacteria from -the pickling solution a higher percentage should have become sour. -Furthermore, if the souring of the two hams in tierce 1 had resulted -from the penetration of the bacteria from the curing pickle, the -souring should have been general throughout the bodies of these hams, -whereas the souring was only evident around the bone and was slight in -degree. - -From this experiment the conclusion would seem justified that the -bacillus which causes ham souring does not usually find its way into -the bodies of the hams from the curing pickle, although it would be -going too far, perhaps, to say that infection never takes place from -the curing pickle. The experiment, however, indicates clearly that the -curing pickles are certainly not the main channel through which the -hams become infected. In referring to the curing pickles, it should be -understood that we refer here to the pickling solutions in which the -hams are immersed, and not to the pumping pickles. The possibility of -infection through the pumping pickle will be discussed later. - - - POSSIBLE INFECTION THROUGH MANIPULATION OR HANDLING. - -There are at least three possible ways in which hams may become -infected from the handling which they receive in preparation for, or -during the process of curing, viz: From the thermometers used in taking -the inside temperatures of the hams, from the pumping needles, and from -the billhooks used in lifting the hams. - - - INFECTION FROM HAM THERMOMETERS. - -The packing-house method of taking the temperatures of hams by means -of a pointed, metal-capped thermometer which is thrust deep into the -bodies of the hams has already been referred to, but deserves to be -described somewhat more in detail, as it will be at once apparent -that this manipulation furnishes a ready means whereby hams may -become infected with putrefactive bacteria. The construction of a ham -thermometer is shown in figure 4. - -[Illustration: A. B. - - FIG. 4.—Diagrammatic views showing construction of ham - thermometer. A, front view, showing open space between metal - point and mercury bulb, which becomes filled with particles of - meat, grease, and dirt; B, side view.] - -The instrument consists of a glass thermometer inclosed in a metal -case, the front portions of the case being cut away so as to expose -the scale above and the mercury bulb below. As was explained before, -the thermometer is thrust deep into the body of the ham so that the -pointed end containing the mercury bulb rests beside or a little behind -the upper portion of the femur, the bone being used as a guide in -introducing the thermometer. - -Ham temperatures are taken at three stages in the preparation for -cure—(1) on the hanging floor, just before the hams go to the chill -rooms, in order to determine the amount of heat lost prior to chilling; -(2) on leaving the chill rooms, in order to determine the thoroughness -of the chill; (3) on the packing floor, just before the hams are placed -in pickle, as a further check on the thoroughness of the chilling. - -In taking the temperatures of hams which have been chilled—and most -of the temperatures are taken subsequent to chilling—it is customary -for the packing-house attendant who has this matter in charge to warm -the thermometer by holding the pointed or bulb end in his hand, so -as to force the mercury column up to about 60° F., or well above the -temperature of hams. The thermometer is then thrust into the ham and -allowed to remain for several minutes, by which time the mercury column -will have fallen to the temperature of the ham. The thermometer is then -slowly withdrawn so as to expose the top of the mercury column, and -an accurate reading is thus obtained of the inside temperature of the -ham. The thermometer is warmed by the hand before each ham is tested, -and this undoubtedly insures more accurate readings than would result -were the thermometer removed from one ham and plunged immediately into -another, but the procedure is open to certain objections, for the open -space between the metal point of the thermometer and the mercury bulb -soon becomes filled with particles of meat and with grease and dirt -from the attendant’s hands, and it is at once apparent that a thermometer -in this condition would furnish a ready means whereby extraneous matter -might be introduced into the bodies of the hams. In other words, a -contaminated thermometer would furnish an excellent means whereby hams -could be inoculated with putrefactive bacteria. - -In order to determine whether hams actually become inoculated in this -manner, the following experiment was carried out: - - -EXPERIMENT TO SHOW WHETHER HAMS BECOME INFECTED FROM HAM THERMOMETERS. - -This experiment was designed to show (1) whether the usual -packing-house method of taking ham temperatures was apt to induce -souring in the hams thus tested, and (2) whether souring would result -in hams which were tested with a thermometer purposely contaminated -with the bacillus isolated from sour hams. - -The experiment was carried out as follows: Thirty hog carcasses were -selected as they entered the hanging floor from the killing floor. They -had been cleaned, eviscerated, and split, and were of the same average -weight and of sufficient size to yield hams weighing from 12 to 14 -pounds. They were divided into three lots of 10 each and were allowed -to remain on the hanging floor for two hours, after which they were -given the usual 48-hour chilling. - - _Lot 1._—The hams in this lot were tested with an ordinary ham - thermometer as they entered the hanging floor, as they left the - hanging floor, and as they left the coolers. The thermometer - used was borrowed from one of the plant attendants and was used - in the condition in which it was received from him; that is, it - was not cleaned or disinfected prior to use. - - _Lot 2._—The hams in this lot were tested as they entered the - hanging floor with a thermometer which had been previously - cleaned and disinfected and then dipped in a culture suspension - of the meat-souring bacillus which was isolated from sour - hams. The thermometer was dipped in the culture suspension - before each ham was tested. No further temperatures were taken - of these hams. The thermometer was carefully cleaned and - disinfected before it was returned to the attendant from whom - it was borrowed. - - _Lot 3._—The hams in this lot were not tested at all, and were - intended as checks on the cure. - -The three lots of carcasses were carefully tagged and were chilled in a -special cooler to themselves. Upon leaving the cooler the hams were cut -from the carcasses and trimmed. The three lots of hams were then cured -in separate tierces. All of the hams were subjected to exactly the same -cure. - -The pickles used were the regular pumping and regular curing pickles of -the establishment at which the experiment was carried out. - -The hams in lot 3 were pumped first and those in lot 1 were pumped -next. The needle was then removed and a fresh, clean needle was used -for lot 2. This was done in order to prevent the possibility of -carrying over bacteria from one lot of hams to another on the pumping -needle. The tierces were thoroughly cleaned with boiling water before -being used. The curing was carried out in a pickling cellar which was -held at 33° to 36° F., the temperature never rising above the latter -figure. The tierces were rolled three times during the curing. The -details and results were as follows: - - _Tierce 1._—Contained 20 hams, half of which were pumped in - both body and shank and half in the shank only. These hams were - taken from the carcasses in lot 1 and had been tested several - times with a ham thermometer, as already described. - - Result: At the end of the cure it was found that of the 10 hams - which were pumped in the shank, 5 showed well-marked souring in - the body, while of the 10 hams which were pumped in both body - and shank, 2 showed slight souring in the body. - - _Tierce 2._—Contained 20 hams, which were pumped in the same - manner as those in tierce 1. These hams were taken from the - carcasses in lot 2 and had been tested once with a thermometer - which was dipped in a culture suspension of the bacillus - isolated from sour hams. - - Result: The 10 hams which were pumped in the shank only all - became sour. When they were tried out at the end of the cure, - they showed pronounced souring throughout the entire body and - were classed as “stinkers” by the meat inspector who examined - them. The souring extended through to the bone marrow of the - femur in all of these hams. Of the 10 hams which were pumped in - both body and shank, 7 showed well-marked souring in the body, - but not as pronounced as in those pumped in the shank only; in - five of these hams the souring extended through to the bone - marrow of the femur, while in 2 the bone marrow remained sweet. - - _Tierce 3._—Contained 20 hams, which were pumped in the same - manner as those in the two preceding tierces. These hams were - not tested with a thermometer, and were put down as a check - on the cure. They were pumped with the same pumping pickle, - subjected to the same cure, and held under precisely the same - conditions as the hams in the two preceding tierces. - - Result: When tested at the end of the cure, all of these hams - were found to be perfectly sound and sweet. - - - _Results of experiment to show whether hams become infected from ham - thermometers._ - ────────┬────────┬───────────┬──────────────┐ - │ │ │ │ - │ │ │ │ - No. of │ Number │ Average │ How pumped. │ - tierce.│ of │ weight of │ │ - │ hams. │ hams. │ │ - ────────┼────────┼───────────┼──────────────┤ - │ │ _Pounds._ │ │ - │ │ │ │ - │ │ │{ 10 in shank │ - │ │ │{ │ - 1 │ 20 │ 12-14 │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ 10 in body │ - │ │ │{ and shank │ - │ │ │ │ - │ │ │{ 10 in shank │ - 2 │ 20 │ 12-14 │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ │ - │ │ │{ 10 in body │ - │ │ │{ and shank │ - │ │ │ │ - │ │ │{ 10 in shank │ - 3 │ 20 │ 12-14 │{ │ - │ │ │{ 10 in body │ - │ │ │{ and shank │ - ────────┴────────┴───────────┴──────────────┘ - - ────────┬─────────────────┬────────────────── - │ │ Condition at - │ │ end of cure. - No. of │ ├───────┬────────── - tierce.│ Treatment. │Number │Percentage - │ │of sour│ of sour - │ │ hams. │ hams. - ────────┼─────────────────┼───────┼────────── - │ │ │ - │Tested at several│ 5 │ 50 - │stages in │ │ - 1 │preparation for │ │ - │cure with ham │ │ - │thermometer which│ │ - │had not been │ │ - │cleaned. │ │ - │ do │ 2 │ 20 - │ │ │ - │ │ │ - │Tested once with │ 10 │ 100 - 2 │ham thermometer │ │ - │dipped in culture│ │ - │suspension of │ │ - │anaerobic │ │ - │bacillus isolated│ │ - │from sour hams. │ │ - │ do │ 7 │ 70 - │ │ │ - │ │ │ - 3 │Not tested with │ 0 │ 0 - │thermometer. │ │ - │ do │ 0 │ 0 - ────────┴─────────────────┴───────┴────────── - -Several hams from each tierce were examined bacteriologically. cultures -being taken from the meat near the bone and from the bone marrow of the -femur. - -In the sour hams from tierce 1 cultures taken from the meat near the -bone showed the same anaerobic bacillus noted in other sour hams (i.e., -the same bacillus which caused souring in Experiments I and II), -but these cultures were contaminated with other bacteria which were -probably introduced on the thermometer along with the ham-souring -bacillus. None of the contaminating bacteria were capable, however, -of producing a sour-meat odor when grown on the egg-pork medium. Pure -cultures of the ham-souring bacillus were obtained from the bone marrow -of some of these hams, showing that this bacillus had penetrated -through to the bone marrow while the other bacteria had not. - -From the sour hams in tierce 2 the ham-souring bacillus was recovered -readily, and often in pure culture, from the hams which had been pumped -in the shank only, whereas it was usually contaminated with pickle -bacteria in the hams which had been pumped in both body and shank. - -In the case of the sound hams in tierce 3, cultures taken from the meat -near the bone and from the bone marrow of the femur were negative in -the hams which had been pumped in the shank only, while cultures taken -from corresponding points in the hams pumped in both body and shank -showed ordinary pickle bacteria, which had evidently been introduced -into the bodies of these hams in the pumping pickles. None of these -hams exhibited the slightest sour odor. - -_Summary of experiment._—In this experiment 20 hams (tierce 1) were -tested with an ordinary ham thermometer in the usual packing-house -manner. Half of these hams were subjected to the mild cure and half -were given the regular cure, with the result that 50 per cent of those -receiving the mild cure and 20 per cent of those receiving the regular -cure became sour. - -A second lot of 20 hams (tierce 2) were tested with a thermometer -which had been purposely contaminated with a culture suspension of the -ham-souring bacillus. These hams were cured in the same manner as the -first lot, with the result that all of those receiving the mild cure -and 70 per cent of those receiving the regular cure became sour. - -A third lot of 20 hams (tierce 3) which had not been tested at all were -cured in the same manner as the two preceding lots, as a check on the -cure. All of these hams were sweet at the end of the cure. - -Inasmuch as the three lots of hams were cured under precisely the same -conditions and were handled in the same manner prior to pickling, the -only difference being that the hams in tierces 1 and 2 were tested with -the ham thermometer while those in tierce 3 were not, we must conclude -that the souring of the hams in tierces 1 and 2 resulted from the -testing which these hams received. In the case of tierce 1 the hams -became infected from a thermometer which, in the ordinary routine use -of the packing house, had become accidentally contaminated with the -ham-souring bacillus. In the case of tierce 2 the hams became infected -from a thermometer which had been artificially contaminated with the -bacillus. The high percentage of sours in this last lot is due to -the fact that these hams were heavily infected with the ham-souring -bacillus, for owing to the construction of the ham thermometer many -thousands of the bacilli were unquestionably introduced into each -ham on the point of the thermometer. In the ordinary routine of ham -testing, where hams become infected from foreign matter introduced on -the thermometer, the percentage of souring, as shown in tierce 1, would -be less, for it is not to be supposed that ham thermometers are always -contaminated with the ham-souring bacillus, but that they only become -so at times, and that probably only a few of the bacilli are then -introduced. - -This experiment, we think, proves conclusively (1) that the ham-souring -bacillus may be introduced into the bodies of hams on the thermometers -used in testing the hams, and (2) that the packing-house method of -taking ham temperatures by means of a thermometer which is thrust deep -into the bodies of the hams may cause souring in the hams thus tested. - -As a further proof that hams may become contaminated in this manner, -a series of cultures were made from scrapings taken from ham -thermometers. The scrapings consisted of the accumulations of bits -of meat, grease, and dirt that collect on the thermometers, and were -taken from the thermometers while the latter were in ordinary routine -use in the packing house. In a series of six cultures which were made -from such scrapings at different times, the same bacillus which was -isolated from sour hams and shown to cause meat souring was found three -times. In other words, the ham-souring bacillus was present in 50 per -cent of the cultures made from thermometer scrapings, and many hams -undoubtedly become infected from the thermometers. Souring would be -almost certain to result in mild-cure hams if these hams were tested -with a thermometer which had become accidentally contaminated with -the ham-souring bacillus, as the bacillus would have time to develop -within the bodies of the hams before being inhibited by the curing -pickle, which penetrates slowly into the bodies of these hams. In the -case of regular cure hams—that is, hams which are pumped in both body -and shank—souring would be much less apt to occur after the use of a -contaminated thermometer, as these hams are more or less saturated with -a strong pumping pickle at the beginning of the cure, which would tend -to inhibit the growth of any bacteria that might be introduced on the -thermometers. - -The fact that souring may result in hams from the use of a contaminated -thermometer would explain the occurrence of several sours in one vat, -for in testing hams just before they go into cure several hams are -usually tested in succession, and these would in all likelihood go into -the same vat. Supposing the thermometer to have been contaminated with -the ham-souring bacillus at the time these hams were tested, this would -explain a fact which has been often noted, namely, the occurrence of -several sours in one vat while other vats containing the same run of -hams show no sours. - -If souring resulted in all of the hams which are subjected to a -thermometer test in the daily routine of the packing house, this -manipulation alone might account for nearly all of the sours which -occur, but the experiment which has been just described shows that -all of these hams do not become sour. In tierce 1, where each ham -was subjected to three thermometer tests at different times, souring -resulted in 35 percent (this includes both mild and regular cure) of -the hams thus tested, and in actual practice the percentage of sours in -hams which have been subjected to the thermometer test would probably -be somewhat less. Quite a large percentage of sour hams are thus left -unaccounted for by the thermometer test, and we believe that these are -chiefly the result of contamination carried in on the pumping needles -or in the pumping pickles. - - - INFECTION FROM PUMPING NEEDLES. - -In view of the results obtained in the last experiment, in which it was -shown that hams may become infected from the use of ham thermometers, -it seemed not improbable that hams might also become infected from -the pumping needles, which, like the thermometers, are thrust deep -into the bodies of the hams beside the bone. In order to throw some -light upon this point, cultures were taken from the grease and dirt -that accumulate on the shields at the bases of the pumping needles, -as such material must undoubtedly be carried into the hams at times -on the needles. The ham-souring bacillus was found several times in -these cultures, and hence it is fair to infer that hams may also -become infected at times from the pumping needles, just as they become -infected from the thermometers. Bits of contaminated meat and grease -and particles of dirt carried in on the pumping needles would be forced -out into the hams by the pumping pickle, which passes out through small -openings or fenestræ in the needles, and this probably affords one -explanation as to why so many more body sours occur in the mild-cure -hams. In the mild-cure hams, which are pumped in the shank only, the -pumping needle is introduced near the femorotibial articulation, and -the shank is saturated at the start with a strong brine solution, while -the body of the ham is not. If the ham-souring bacillus were carried -into these hams on the pumping needle, the growth of the bacillus in -the shank would be inhibited by the strong brine solution with which -the shank is saturated, but there would be nothing to prevent the -bacillus from growing upward into the body of the ham, which has not -been pumped and is free from pickle. This would also explain the fact -that the souring often starts at the knee joint and extends upward into -the body of the ham. In the case of the regular cure hams, where the -ham is pumped in both body and shank, the entire ham is more or less -saturated at the start with the strong brine of the pumping pickle, -which tends to inhibit the growth of the ham-souring bacillus even -if this bacillus should find its way into these hams on the pumping -needles. It is in the mild-cure or partly pumped hams, where the body -of the ham is left unpumped, that the ham-souring bacillus finds its -best opportunity for development, and the greater proportion of the -sours that occur in the packing house are found in these hams. - -As regards the possibility of infection from the pumping pickle -itself, it does not seem probable that this would often occur, for -the pumping and curing pickles are always prepared on an upper floor -of the pickling houses and are delivered to the pickle cellars in -closed pipes, so the chances for the accidental contamination of these -solutions from floating dust or dirt would not be great. Furthermore, -the strong brine of the pumping pickle would completely inhibit the -growth of the ham-souring bacillus, and the bacillus would be incapable -of multiplying, even if it found its way into the pickle. On the other -hand, laboratory experiments show that the bacillus or its spores may -remain alive for a considerable length of time in the pumping pickle, -so the possibility of infection from this source can not be overlooked. - - - INFECTION FROM BILLHOOKS. - -After the hams are cut from the carcasses they are handled entirely -by means of billhooks. In handling the hams the hooks are inserted -beneath the skin of the shank at a point just above the tibio-femoral -articulation. The hooks should be inserted in the connective tissue -beneath the skin and should not penetrate the muscular tissue to any -depth. When the hams lie in the right position, with the butt or large -portion away from and the shank toward the operator, it is an easy -matter to pick them up in the proper manner; but when they lie at -different angles and are being rapidly handled it is almost impossible -to prevent the hook from penetrating the muscular tissues, and if the -hook should penetrate to the bone it might carry in foreign matter -contaminated with the meat-souring bacillus. It is not probable that -many hams become contaminated in this way, as the men who handle the -hams are very skillful in manipulating their hooks; but the possibility -that hams may become contaminated in this manner should not be entirely -overlooked. - - - BIOLOGICAL AND MORPHOLOGICAL CHARACTERISTICS OF THE HAM-SOURING - BACILLUS. - - - CONDITIONS FAVORABLE TO GROWTH. - -The most favorable medium for the growth of the organism was found -to be the modified egg-meat mixture of Rettger, which has been -previously described. In this medium the organism develops rapidly -at a temperature of 20° to 25° C., giving rise to the characteristic -sour-meat odor. Like the bacillus described by Klein, it also grows -readily on pork-agar and pork-bouillon containing glucose, but differs -from Klein’s bacillus in that it will grow, though less luxuriantly, -on ordinary nutrient media—agar, gelatin, and bouillon—without the -addition of glucose. - -The optimum temperature for growth is 20° to 25° C. The organism does -not grow at incubator temperature (37.5° C.). At ice-box temperature -(8° to 10° C.) it develops readily, although the growth is less rapid -than at 20° to 25° C. That the organism will develop at even lower -temperatures was shown in the inoculation experiments with hams, where -it developed and multiplied extensively in the bodies of the hams at -the temperature of the pickling cellars, which are held usually at 34° -to 36° F. (1° to 2° C.). - -The organism develops best in a neutral or slightly alkaline medium. - - - GROWTH ON DIFFERENT CULTURE MEDIA. - -_Growth on egg-pork medium._—At a temperature of 20° to 25° C. the -cultures show a slight but distinct sour odor in from two to three -days. This odor, as before stated, closely resembles the odor of a -sour ham. Egg-pork cultures from three to five days old were given to -a trained meat inspector, who knew nothing whatever as to the contents -of the tubes, and he was asked to describe the odor; he described it as -that of a sour ham. - -At one week the albumins of the medium are gelatinized or partly -coagulated and the odor is more pronounced. At ten days the albumins -are completely coagulated except at the surface, where there is -no apparent growth; the odor is more putrefactive in nature, and -the reaction of the medium is slightly acid. At three weeks the -coagulated albumin splits up into fragments and appears to undergo a -slow digestion, gas bubbles form in the lower portion of the culture, -and the odor becomes distinctly putrefactive in character. The slow -digestion of the albumin is probably due to a proteolytic enzyme -elaborated by the bacillus. - -At the end of a week a dark zone usually appears at the surface of the -coagulated albumin and gradually darkens until it becomes almost black. -This zone is probably due to a pigment elaborated by the bacillus. - -At ice-box temperature (8° to 10° C.) the same changes and the same -odor were noted, but were somewhat slower in developing. - -_Glucose-pork-agar._—This medium was prepared from pork in the same -manner as beef-agar, and contained 1 per cent of glucose. The organism -grows readily on this medium and may be conveniently cultivated in deep -stab cultures. The medium was always thoroughly boiled and then rapidly -cooled in order to expel the inclosed air. The growth of the organism -was found to vary considerably with the reaction. - -When the reaction was +1.5, deep stab cultures at three days (20° to -25° C.) showed a well-marked arborescent growth, appearing as delicate -filaments extending outward from the line of stab. The growth stopped -within one-fourth or one-half inch of the surface of the agar on -account of the presence of oxygen in the upper part of the culture -medium. As the growth extended toward the walls of the test tube the -agar became clouded, and there were sometimes gas bubbles in the depth -of the agar, but the gas formation was not extensive. - -When the reaction of the agar is neutral or slightly alkaline, -extensive gas formation occurs and the agar is often much broken up. - -The cultures developed a disagreeable, somewhat putrefactive odor, -but did not give the characteristic sour-ham odor obtained from the -egg-pork cultures. - -The organism was also grown on anaerobic agar plates by Zinsser’s method, -which is said to give absolutely anaerobic conditions. The colonies on -agar have a cottony or woolly appearance at first, and spread slowly, -with slightly irregular margins. - -In glucose-pork-agar to which azolitmin was added the azolitmin in the -lower portion of deep stab cultures was completely decolorized in five -days at room temperature (20° to 25° C). - -In glucose-pork-agar containing neutral red the red color in the lower -portion of the tube was changed to yellow with the development of -fluorescence. - -_Neutral gelatin._—Tubes of ordinary neutral gelatin without the -addition of glucose were inoculated and held at ice-box temperature -(8° to 10° C). At five days a delicate white growth appeared along -the line of stab in the lower portion of the tube. At seven days the -growth showed fine radial striæ, presenting an arborescent or tree-like -appearance, and extended halfway from the line of stab to the walls of -the test tube. At two weeks the growth had caused a delicate clouding -of the medium in the lower portion of the tube. At three weeks the -gelatin in the lower portion of the tube had become liquefied and the -growth had settled to the bottom as a white precipitate. - -In gelatin containing glucose, gas bubbles are formed in the depth -of the medium through the splitting up of the glucose, and the -characteristic arborescent growth is obscured. - -_Glucose-pork-bouillon._—This medium was prepared from pork instead -of beef and contained 1 per cent of glucose. The best results were -obtained when the reaction of the medium was neutral or slightly -alkaline. - -Culture tubes, which had been previously boiled to expel the contained -air and then inoculated, were held in a Novy jar, in an atmosphere of -hydrogen at a temperature of 20° to 25° C. At three days the tubes -showed well-marked clouding. At one week the growth appeared as a -heavy, white, flocculent, cottony precipitate in the bottom of the -tubes with a slight flocculent precipitate above. When the culture was -removed from the jar and shaken, the heavy, flocculent precipitate at -the bottom of the tube broke up without much difficulty, giving rise to -a heavy uniform clouding with some small floating masses, which soon -settled to the bottom. On shaking the tube some evolution of gas in the -form of very fine bubbles was noticed. - -In Smith fermentation tubes containing neutral glucose-pork-bouillon -the closed arm of the tube shows well-marked clouding with gas -formation at three days at room temperature (20° to 25° C). The -growth has a tufted, cottony appearance, and there are many filaments -and threads. The growth settles to the bottom of the closed arm as -a cottony, white precipitate (see Pl. IV). The organism splits the -glucose vigorously, and at 10 days the tubes show from 40 to 50 -per cent of gas. The bouillon in the open arm of the tube remains -unclouded. The maximum gas production at room temperature is reached -in from 10 to 14 days, by which time the growth in the closed arm has -completely settled into the bend of the tube, leaving the bouillon -in the closed arm clear. The gas formula, as determined by Smith’s -method, was H/CO₂ = 5/1. The reaction of the bouillon becomes acid to -phenolphthalein. - -The organism will grow on ordinary neutral bouillon without the -addition of glucose, and in Smith tubes containing this medium a small -amount of gas was formed, due to the splitting of the muscle sugar. - -The bacillus also grows in a sugar-free broth—that is, a broth free -from muscle sugar—and from cultures grown in this medium a well-marked -indol test was obtained. - -_Litmus-milk._—The organism was grown in litmus-milk in Smith -fermentation tubes at 20° to 25° C. At seven days the litmus in the -lower portion of the closed arm had assumed a brownish-buff color. -At two weeks the litmus in the closed arm had been reduced to a -brownish-buff color except at the top of the tube, where a pale, bluish -tinge remained, and the litmus in the open arm showed very slight -reddening as compared with a check tube. At three weeks the litmus in -the closed arm was entirely reduced to a light, brownish-buff color, -and the litmus in the open arm showed a slight but distinct reddening -as compared with the check. The reddening of the litmus in the open arm -was evidently due to the transfusion of acids formed by the growth of -the bacillus in the closed arm. After several weeks the milk is slowly -peptonized, probably as a result of enzyme action. - - - MORPHOLOGY. - -The organism is a large bacillus having an average size of 4 to 8 μ in -length by 0.5 to 0.7 μ in thickness, but there are many longer forms -measuring from 10 to 20 μ in length. It develops in long, irregular -chains or filaments, which at times show a slightly spiral form. - -[Illustration: - - FIG. 5.—Ham-souring bacillus (_Bacillus putrefaciens_) grown - on egg-pork medium, showing tendency to form chains. Partly - developed and fully developed spores are shown at ends of rods; - also free spores. (Pen-and-ink drawing made with camera lucida - from preparation stained by Gram’s method. × 640.)] - -The individual organisms show at times a widely open, slightly spiral -form, which was more apparent in hanging-drop preparations made -from bouillon cultures, where the organisms had been comparatively -undisturbed. This appearance was also noted at times in the stained -sections of soured muscular tissue, where the organisms were stained in -place. The organism possesses no motility. It stains with the ordinary -aniline dyes and by Gram’s method. - - - SPORE FORMATION. - -The organism develops large, terminal spores, which are at first oval, -but when fully developed are perfectly round and measure from 1.5 to 2 -μ in diameter. - -Spores develop rapidly in the egg-pork medium at 20° to 25° C., fully -developed spores being noted in from five to seven days. At ice-box -temperature (8° to 10° C.) partly developed spores were noted in the -egg-pork medium at 10 days and fully developed spores at 2 weeks. - -Occasional spores were noted in old agar and gelatin cultures, but -abundant spore formation was seen only in the egg-pork medium. No -spores were noted in bouillon cultures, even at 10 weeks. - - - RESISTANCE TO HEAT AND CHEMICAL AGENTS. - -In its vegetative form the bacillus is killed at 55° C. in 10 minutes. -The spores survive a temperature of 80° C. for 20 minutes, but are -killed at 100° C. in 10 minutes. - -When sodium chlorid and potassium nitrate were added to glucose-pork -broth in varying amounts, it was found that 3 per cent of sodium -chlorid or 3 per cent of potassium nitrate was sufficient to inhibit -completely the growth of the bacillus at room temperature (20° to 25° -C.). - -While the growth of the bacillus was inhibited by sodium chlorid and -potassium nitrate as just stated, it was found that very much stronger -solutions of the two salts failed to destroy the bacillus. Thus it was -found that the bacillus or its spores retained their vitality after -an exposure of 30 days in a solution containing 23 per cent of sodium -chlorid and 6 per cent of potassium nitrate. - - - GAS PRODUCTION. - -The organism splits glucose, but not lactose or saccharose. That -it possesses the power of splitting muscle sugar was shown by the -formation of gas in Smith fermentation tubes containing ordinary -neutral bouillon without the addition of any sugar. - -The formation of gas in glucose bouillon varies considerably with -the reaction of the medium. The largest amount of gas was formed -when the broth was neutral or slightly alkaline. When the reaction -of the broth was distinctly acid or distinctly alkaline the amount -of gas was diminished. The gas which is formed in bouillon cultures -consists chiefly of hydrogen and carbon dioxide. In order to collect a -sufficient amount of the gas for analysis, two large fermentation tubes -capable of holding 150 cubic centimeters each were constructed. These -tubes were filled with pork-bouillon and inoculated with the bacillus. -After 20 days at room temperature (20° to 25° C.) the gas was collected -and the carbon dioxide and hydrogen determined, with the following -result: - - Cubic centimeters. - Total amount of gas collected 37.7 - Carbon dioxide, by absorption with NaOH 6.2 - Hydrogen, by difference 31.5 - -This analysis gives an approximate gas formula of H/CO₂ = 5/1, which -agrees with the gas formula as determined in the small fermentation -tubes by Smith’s method. - -In hams which had undergone spontaneous souring and in hams which had -been artificially soured by inoculation, hydrogen-sulphid was often -noted when the sour portions of the meat were tested with lead-acetate -paper, but no distinct odor of the gas could be obtained. Hydrogen -sulphid was also noted in egg-pork cultures of the bacillus. - - - ACID PRODUCTION. - -In glucose-bouillon, butyric and lactic acids are formed and the -reaction of the medium becomes distinctly acid. Butyric and lactic -acids were also noted in the egg-pork cultures. - -A series of Smith fermentation tubes containing 10 c. c. each of -glucose-pork broth medium was inoculated with the bacillus and held -at room temperature (20° to 25° C.). These cultures were titrated -against [N/40]NaOH, with phenolphthalein as an indicator at intervals -of two days up to nineteen days, and then at two-week intervals up to -sixty-one days. Three of the cultures were titrated each time so as to -give a fair average of the acidity of the cultures, and an uninoculated -check tube was also titrated each time to see if there was any change -in the reaction of the medium. The results of the titrations are shown -in the following table: - - - _Acidity determinations in glucose-pork broth cultures._ - - ──────────────┬───────┬───────┬───────┬────────┬───────┬─────────── - Age of culture│Culture│Culture│Culture│Average.│Medium.│Acidity of - (days). │ A. │ B. │ C. │ │ │ culture. - ──────────────┼───────┼───────┼───────┼────────┼───────┼─────────── - │ │ │ │ │ │_Per cent._ - 2 │ 0.038 │ 0.030 │ 0.040 │ 0.036 │ 0.009 │ 0.027 - 4 │ .105 │ .100 │ .102 │ .102 │ .009 │ .093 - 6 │ .106 │ .110 │ .109 │ .108 │ .009 │ .099 - 8 │ .124 │ .115 │ .117 │ .119 │ .009 │ .110 - 10 │ .128 │ .130 │ .126 │ .128 │ .009 │ .119 - 12 │ .129 │ .120 │ .129 │ .126 │ .009 │ .117 - 19 │ .126 │ .125 │ .125 │ .125 │ .009 │ .116 - 33 │ .125 │ .123 │ .125 │ .124 │ .009 │ .115 - 47 │ .122 │ .120 │ .121 │ .121 │ .009 │ .112 - 61 │ .121 │ .116 │ .119 │ .118 │ .009 │ .109 - ──────────────┴───────┴───────┴───────┴────────┴───────┴─────────── - -From the above table it will be seen that the maximum acidity was -reached at ten days, after which there was a gradual reduction in the -acidity, due probably to the formation of ammonia compounds. - - - PATHOGENIC PROPERTIES. - -Rabbits, guinea pigs, and white mice were inoculated and fed with -cultures of the bacillus without effect, from which it would appear -that the bacillus possesses no pathogenic or disease-producing -properties. - - - NATURE OF THE BACILLUS. - -The bacillus is essentially a saprogenic bacterium with zymogenic -properties. A preliminary study of the chemical changes which take -place in sour hams shows that these changes are of a putrefactive -nature. Hams which had undergone spontaneous souring were compared -with hams which had been artificially soured by inoculation, and the -chemical changes were found to be identical. A chemical study was also -made of the changes taking place in egg-pork cultures of the bacillus -at different stages of growth, and these changes were found to be of a -putrefactive nature and similar in character to the changes which occur -in sour hams. Among the putrefactive products formed by the growth of -the bacillus in the egg-pork medium were indol, skatol, volatile fatty -acids, skatol-carbonic acid, and hydrogen sulphid.[4] - -[4] The tests for the putrefactive products formed by the growth -of the bacillus in the egg-pork medium were made by P. Castleman, -of the Biochemic Division, who also determined the percentage -composition of the gas formed by the growth of the bacillus in the -glucose-pork-bouillon medium. - -[Illustration: - - BUL. 132, BUREAU OF ANIMAL INDUSTRY, U. S. DEPT. OF AGRICULTURE. - PLATE IV. - - GLUCOSE BOUILLON CULTURE IN SMITH FERMENTATION TUBE AT FOUR - DAYS. CULTURE GROWN AT ROOM TEMPERATURE (20° TO 25° C.). GROWTH - CONFINED ENTIRELY TO CLOSED ARM, WITH GAS COLLECTING AT TOP.] - -A more extended study is now being carried on in the Biochemic Division -of the chemical changes which take place in hams during the process of -souring, together with a further study of the chemical changes which -result from the growth of the bacillus in the egg-pork medium. The -results of this investigation will be given in a later paper. - -The bacillus described in this paper belongs to the class of -putrefactive anaerobes, which are widely distributed in nature in dust, -soil, and excrementitious matters. This group of bacteria contains -both pathogenic and nonpathogenic forms. The former have received -considerable attention, but the latter have never been thoroughly -cleared up. The bacillus isolated from sour hams belongs in the latter -category, being possessed of no pathogenic or disease-producing -properties. It occurs in the dust and dirt of the packing house and -finds its way into the hams in the various manipulations to which the -hams are subjected. - -The bacillus described in this paper does not seem to correspond -with any forms heretofore described. It differs from Klei bacillus -(_Bacillus fœdans_) in the following important particulars: (1) It -forms large terminal spores, whereas Klein’s bacillus formed no spores; -(2) it will grow at a temperature of 34° F., while Klei bacillus did -not grow below 50° F.; (3) it produces an acid reaction in culture -media, while Klei bacillus gave a distinctly alkaline reaction; -(4) it will grow on the ordinary nutrient media—gelatin, agar, and -broth—without the addition of glucose, while Klein’s bacillus did not; -(5) it peptonizes the casein in milk, whereas Klein’s bacillus had no -action on milk; (6) it liquefies gelatin more rapidly, causing complete -liquefaction after three weeks at 8° to 10° C., whereas Klein’s bacillus -caused only partial liquefaction after eight weeks at 20° C.; (7) it -can be conveyed -from turbid broth cultures to new culture material by means of the -platinum loop, whereas Klein’s bacillus could not be thus conveyed. - -For the bacillus described in the present paper the following name is -proposed: _Bacillus putrefaciens_. - - - PREVENTION OF HAM SOURING. - -As it has been shown that souring in hams results from the growth -of a bacterium which is introduced into the bodies of the hams in -the various manipulations which the hams undergo, the only way to -eliminate souring in hams, as they are cured in the larger packing -establishments, would be to cure the hams under aseptic or sterile -conditions, which would, of course, be a physical impossibility. - -While it will probably be impossible, therefore, to eliminate souring -entirely under the methods of ham curing which are at present employed -in the larger packing establishments, much can undoubtedly be done -toward reducing the percentage of sours. In the matter of taking ham -temperatures, for instance, if the thermometers used were thoroughly -cleaned and disinfected and the surfaces of the hams seared at the -point where the thermometer is introduced, infection from this source -could be entirely prevented; or it might be possible so to regulate -the temperature of the chill rooms that the taking of ham temperatures -could be discontinued. - -The elimination of the souring that results from the introduction of -foreign matter on the pumping needles could be effected in two ways -only, (1) by not pumping the hams at all, or (2) by pumping them under -sterile or aseptic conditions. As has been stated before, some of the -smaller packing establishments cure their hams without pumping, and in -these establishments the percentage of sours runs very low. When hams -are cured without pumping, however, the period of curing has to be -materially lengthened in order to give the curing pickles sufficient -time to penetrate thoroughly, and this is what the larger plants wish -to avoid because of the greater space and greater number of vats which -would be necessitated. The object of pumping in the larger plants, -where the number of hams handled daily runs into the thousands, is to -hasten the cure and thus prevent the accumulation of a great number of -hams at one time. It is doubtful, therefore, whether the larger packing -houses could conveniently discontinue pumping. - -To pump the hams under aseptic conditions would necessitate a technique -far too elaborate for routine use in the packing house; in fact, -anything like complete asepsis would be out of the question. Certain -measures might be adopted, however, that would tend to prevent the -possible introduction of ham-souring bacilli in the process of pumping. -It would undoubtedly be safer, for instance, to boil the pumping pickle -before use, and the chances of carrying in contaminated foreign matter -on the pumping needles could be lessened by sterilizing the pumps and -needles with boiling water and by frequently dipping the needles, while -in use, in boiling water. If the hams were sprayed with clean water -just prior to pumping, there would be less likelihood of carrying in -foreign matter on the needles. The danger of introducing contaminated -foreign matter on the needles might be further obviated by searing the -surfaces of the hams at the points where the needles are introduced; -but such a procedure would be hardly practicable in the larger packing -houses, where the great number of hams cured necessitates rapid -handling. - -While the danger of possible contamination in pumping, through the -introduction of contaminated foreign matter on the pumping needles, -can not well be avoided, this danger is partly counterbalanced by the -inhibitory action of the pumping pickle, which is strikingly shown in -the experiments which have been described. In these experiments, 100 -hams received large doses of the ham-souring bacillus, half of these -hams being subjected to the mild cure and half to the regular cure, -with the following result: In the case of the mild-cure hams, which -were pumped in the shank only, the percentage of sours was practically -100 per cent, every ham with possibly one exception becoming sour; -whereas in the regular-cure hams, which were pumped in both body and -shank, only 58 per cent of the hams became sour. In other words, the -additional pumping which the regular-cure hams received served to -prevent souring in 42 per cent of these hams. In these experiments the -number of bacteria introduced into the hams was very great, thousands -and even millions of the bacilli being introduced into each ham, -whereas in the routine of the packing house it is not likely that -more than a few of the bacilli are ever introduced at one time on the -thermometers and pumping needles. In view of these results it is safe -to say that in the larger packing houses, where pumping seems to be -necessary, the number of sours could be reduced fully 50 per cent if -all hams were pumped in the body as well as in the shank. - -At present the usual procedure is to pump all hams, both mild and -regular cure, with the same pumping pickle, the mild-cure hams being -pumped in the shank only and the regular-cure hams at two additional -points in the body. The experiments quoted above show that the -additional pumping which the regular-cure hams receive undoubtedly -tends to prevent the development of souring in these hams, and this -result is unquestionably due to the inhibitory action of the salts -contained in the pumping pickle, as it was found by laboratory -experiment that the addition of 3 per cent of sodium chlorid to -culture media is sufficient to inhibit the growth of the ham-souring -bacillus. The pumping pickles consist of strong brine solutions and -always contain considerably more than 3 per cent of sodium chlorid. -If, therefore, the pumping of regular-cure hams were made more -thorough than at present, and all of the deeper portions of the ham -were thoroughly saturated with the strong brine solution, souring -could be largely eliminated, if not entirely prevented, in these hams, -as an unfavorable medium or soil would thus be created in which the -ham-souring bacillus could not develop. The ham-souring bacillus is -able to develop within the bodies of the regular-cure hams because the -pumping of these hams is not always thorough and there are certain -areas in the inner or deeper portions of the hams in which the tissues -are not thoroughly saturated with the pumping pickle. - -Under the present methods of curing, the greater proportion of the -sours occur among the partly pumped or mild-cure hams. These hams are -pumped in the shank only, and the growth of the ham-souring bacillus -within the bodies of these hams is not interfered with until the curing -pickle has penetrated from the outside. As it requires several weeks -for the curing pickle to penetrate thoroughly into the deeper portions -of these hams, the bacillus is thus afforded a considerable interval -in which to develop before it is exposed to the inhibitory action of -the pickle. If these hams could be thoroughly pumped in the body at -the beginning of the cure in the same manner as the regular-cure hams, -the chief loss from ham souring would be eliminated. It would not do, -however, to pump these hams in the body with the same pumping pickle -used in the regular cure, as the meat would be rendered too salty and -the mild flavor of the ham would be lost. There is undoubtedly a demand -for mild-cure hams, otherwise they would not be on the market; and the -question then arises how to pump these hams and still retain a mild -cure. This might be accomplished by pumping these hams with their own -curing pickle, which is usually a milder pickle than that employed in -the regular cure, or an even milder pumping pickle might be used. If -mild-cure hams were pumped in this way, the percentage of souring in -these hams could undoubtedly be greatly diminished without materially -affecting the flavor of the ham. - -To recapitulate briefly, the prevention of ham souring is to be sought -in two ways: (1) Through greater care in handling the hams and the -adoption of precautionary measures to prevent the introduction of the -ham-souring bacillus into the bodies of the hams, and (2) through more -thorough pumping of the deeper or inner portions of the hams, so as to -create an unfavorable soil or medium in which the ham-souring bacillus -can not develop even if it should gain entrance into the bodies of the -hams. - -From what has been said it will be apparent that ham souring can -probably never be entirely eliminated from the packing house under the -present methods of curing, but the adoption of precautionary measures -in testing and pumping hams, together with a more thorough pumping -of all hams in ways similar to those suggested, would unquestionably -reduce very materially the losses from this source. - - - GENERAL SUMMARY AND CONCLUSIONS. - -1. In this paper it has been shown that ham souring, as encountered in -the wet cure where the hams are entirely submerged in pickling fluids, -is due to the growth of an anaerobic bacillus within the bodies of the -hams. This bacillus (_B. putrefaciens_) was found in sour hams obtained -from four different packing establishments. It was isolated and grown -in various laboratory media, in one of which, the egg-pork medium, it -gave rise to the characteristic sour-ham odor. This bacillus was the -only organism that could be isolated from sour hams that was capable of -producing the characteristic sour-ham odor in the egg-pork medium. - -2. When injected into the bodies of sound hams, the bacillus caused -these hams to sour in the process of curing. In hams which had been -inoculated with the bacillus and thus artificially soured, the bacillus -was recovered in cultures taken at points far removed, relatively -speaking, from the point of inoculation, indicating that the bacillus -had multiplied and progressed by extension throughout the bodies of the -hams. - -3. The bacillus possesses no motility, and its extension throughout -the bodies of the hams is a result of multiplication. In its growth it -follows along the connective-tissue bands between the muscle bundles, -which are composed of comparatively loose tissue and afford paths of -least resistance. When it invades the muscle tissue proper, it follows -along the sarcolemma sheaths between the muscle fibers. As a result of -this growth the muscular tissue becomes softer and tends to break more -easily. - -4. The bacillus belongs to the class of putrefactive anaerobes which -are widely distributed in nature in dust, soil, and excrementitious -matters. The bacillus or its spores is present in the dust and dirt -of packing houses and finds its way into the hams in the various -manipulations to which they are subjected. - -5. The bacillus or its spores may be introduced into hams on the -thermometers used in testing the hams, on the pumping needles, and -possibly on the billhooks used in handling the hams. It may also be -carried into the hams in the pumping pickle, and may even find its way -into the hams from the curing pickle, although infection through the -latter channel probably does not often occur. - -6. The bacillus develops in the deeper portions of the ham because of -the anaerobic conditions there prevailing, and souring is most often -encountered, therefore, in the deeper portions of the ham near the -bone. - -7. A preliminary study of the chemical changes which take place in -the process of souring shows that these changes are of a putrefactive -nature, and ham souring, as ordinarily encountered, is to be regarded -as an incipient putrefaction. Hams which had been artificially soured -by injections of culture were compared with sour hams obtained from the -packing house, and the putrefactive changes were found to be identical. - -8. Hams which have once become sour can never be restored to a sound -condition, because of the chemical changes which result from the growth -of the bacillus. In other words, the tissues of the ham undergo certain -chemical changes in the process of souring, and when these changes -have once taken place the tissues can never be restored to a sound -condition. The repumping of slightly soured hams with a strong pumping -pickle will check further souring, by inhibiting the growth of the -bacillus, but will not restore to a sound condition those portions of -the ham which have become sour. - -9. The salts of the pickling fluids have a marked inhibitory action -on the ham-souring bacillus, and sours occur less frequently in -regular-cure hams. - -10. In regular-cure hams the growth of the ham-souring bacillus is -restricted and often completely inhibited as a result of the additional -pumping which these hams receive, whereby they are more or less -saturated with pickle at the beginning of the cure. - -11. If the pumping of regular-cure hams were more thorough and all -of the deeper portions of the ham were thoroughly saturated with the -pumping pickle, souring could be largely eliminated if not entirely -prevented in the hams, as an unfavorable medium or soil would thus -be created, in which the ham-souring bacillus could not develop. The -reason that souring does develop in regular-cure hams is because the -pumping is not always thorough and there are certain areas in the -deeper portions of these hams which are not saturated with the pumping -pickle. - -12. Under the present methods of curing, the partly pumped or mild-cure -hams furnish the greater proportion of the sours, as these hams are not -pumped in the body and the growth of the ham-souring bacillus within -the bodies of these hams is not interfered with until the curing pickle -has penetrated from the outside. As it requires several weeks for the -curing pickle to penetrate thoroughly into the deeper portions of these -hams, the bacillus is thus afforded a considerable interval in which to -develop. - -13. The percentage of souring in the mild-cure hams could be greatly -reduced without materially affecting the cure by pumping these hams -with their own curing pickle, which is usually a milder pickle than -that employed in the regular cure; and if the pumping were thorough -the number of sours in these hams could be reduced to a small figure. - -14. The only way by which ham souring could be entirely eliminated from -the larger packing establishments under the present methods of curing -would be to handle the hams throughout under aseptic conditions, and -this, for obvious reasons, would be an impossibility. The losses from -ham souring may be materially reduced, however, by greater care in -handling the hams and the adoption of precautionary measures designed -to prevent the introduction of contaminated foreign matter into the -bodies of the hams, together with more thorough methods of pumping. - - - ACKNOWLEDGMENTS. - -In conclusion, the writer desires to express his obligations to Dr. S. -E. Bennett, of the Inspection Division, inspector in charge at Chicago, -for the assignment of trained meat inspectors to assist in the work, -as well as for kind assistance in obtaining data and material for -laboratory study, and to Dr. L. E. Day, of the Pathological Division, -who kindly prepared the sections which are figured and described in the -present article. - -*** END OF THE PROJECT GUTENBERG EBOOK A BACTERIOLOGICAL STUDY OF HAM -SOURING *** - -Updated editions will replace the previous one--the old editions will -be renamed. - -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the -United States without permission and without paying copyright -royalties. Special rules, set forth in the General Terms of Use part -of this license, apply to copying and distributing Project -Gutenberg-tm electronic works to protect the PROJECT GUTENBERG-tm -concept and trademark. Project Gutenberg is a registered trademark, -and may not be used if you charge for an eBook, except by following -the terms of the trademark license, including paying royalties for use -of the Project Gutenberg trademark. If you do not charge anything for -copies of this eBook, complying with the trademark license is very -easy. You may use this eBook for nearly any purpose such as creation -of derivative works, reports, performances and research. Project -Gutenberg eBooks may be modified and printed and given away--you may -do practically ANYTHING in the United States with eBooks not protected -by U.S. copyright law. Redistribution is subject to the trademark -license, especially commercial redistribution. - -START: FULL LICENSE - -THE FULL PROJECT GUTENBERG LICENSE -PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK - -To protect the Project Gutenberg-tm mission of promoting the free -distribution of electronic works, by using or distributing this work -(or any other work associated in any way with the phrase "Project -Gutenberg"), you agree to comply with all the terms of the Full -Project Gutenberg-tm License available with this file or online at -www.gutenberg.org/license. - -Section 1. General Terms of Use and Redistributing Project -Gutenberg-tm electronic works - -1.A. By reading or using any part of this Project Gutenberg-tm -electronic work, you indicate that you have read, understand, agree to -and accept all the terms of this license and intellectual property -(trademark/copyright) agreement. If you do not agree to abide by all -the terms of this agreement, you must cease using and return or -destroy all copies of Project Gutenberg-tm electronic works in your -possession. If you paid a fee for obtaining a copy of or access to a -Project Gutenberg-tm electronic work and you do not agree to be bound -by the terms of this agreement, you may obtain a refund from the -person or entity to whom you paid the fee as set forth in paragraph -1.E.8. - -1.B. "Project Gutenberg" is a registered trademark. It may only be -used on or associated in any way with an electronic work by people who -agree to be bound by the terms of this agreement. There are a few -things that you can do with most Project Gutenberg-tm electronic works -even without complying with the full terms of this agreement. See -paragraph 1.C below. There are a lot of things you can do with Project -Gutenberg-tm electronic works if you follow the terms of this -agreement and help preserve free future access to Project Gutenberg-tm -electronic works. See paragraph 1.E below. - -1.C. The Project Gutenberg Literary Archive Foundation ("the -Foundation" or PGLAF), owns a compilation copyright in the collection -of Project Gutenberg-tm electronic works. Nearly all the individual -works in the collection are in the public domain in the United -States. If an individual work is unprotected by copyright law in the -United States and you are located in the United States, we do not -claim a right to prevent you from copying, distributing, performing, -displaying or creating derivative works based on the work as long as -all references to Project Gutenberg are removed. Of course, we hope -that you will support the Project Gutenberg-tm mission of promoting -free access to electronic works by freely sharing Project Gutenberg-tm -works in compliance with the terms of this agreement for keeping the -Project Gutenberg-tm name associated with the work. You can easily -comply with the terms of this agreement by keeping this work in the -same format with its attached full Project Gutenberg-tm License when -you share it without charge with others. - -1.D. The copyright laws of the place where you are located also govern -what you can do with this work. Copyright laws in most countries are -in a constant state of change. If you are outside the United States, -check the laws of your country in addition to the terms of this -agreement before downloading, copying, displaying, performing, -distributing or creating derivative works based on this work or any -other Project Gutenberg-tm work. The Foundation makes no -representations concerning the copyright status of any work in any -country other than the United States. - -1.E. Unless you have removed all references to Project Gutenberg: - -1.E.1. The following sentence, with active links to, or other -immediate access to, the full Project Gutenberg-tm License must appear -prominently whenever any copy of a Project Gutenberg-tm work (any work -on which the phrase "Project Gutenberg" appears, or with which the -phrase "Project Gutenberg" is associated) is accessed, displayed, -performed, viewed, copied or distributed: - - This eBook is for the use of anyone anywhere in the United States and - most other parts of the world 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. If you are not located in the - United States, you will have to check the laws of the country where - you are located before using this eBook. - -1.E.2. If an individual Project Gutenberg-tm electronic work is -derived from texts not protected by U.S. copyright law (does not -contain a notice indicating that it is posted with permission of the -copyright holder), the work can be copied and distributed to anyone in -the United States without paying any fees or charges. If you are -redistributing or providing access to a work with the phrase "Project -Gutenberg" associated with or appearing on the work, you must comply -either with the requirements of paragraphs 1.E.1 through 1.E.7 or -obtain permission for the use of the work and the Project Gutenberg-tm -trademark as set forth in paragraphs 1.E.8 or 1.E.9. - -1.E.3. If an individual Project Gutenberg-tm electronic work is posted -with the permission of the copyright holder, your use and distribution -must comply with both paragraphs 1.E.1 through 1.E.7 and any -additional terms imposed by the copyright holder. Additional terms -will be linked to the Project Gutenberg-tm License for all works -posted with the permission of the copyright holder found at the -beginning of this work. - -1.E.4. Do not unlink or detach or remove the full Project Gutenberg-tm -License terms from this work, or any files containing a part of this -work or any other work associated with Project Gutenberg-tm. - -1.E.5. Do not copy, display, perform, distribute or redistribute this -electronic work, or any part of this electronic work, without -prominently displaying the sentence set forth in paragraph 1.E.1 with -active links or immediate access to the full terms of the Project -Gutenberg-tm License. - -1.E.6. You may convert to and distribute this work in any binary, -compressed, marked up, nonproprietary or proprietary form, including -any word processing or hypertext form. However, if you provide access -to or distribute copies of a Project Gutenberg-tm work in a format -other than "Plain Vanilla ASCII" or other format used in the official -version posted on the official Project Gutenberg-tm website -(www.gutenberg.org), you must, at no additional cost, fee or expense -to the user, provide a copy, a means of exporting a copy, or a means -of obtaining a copy upon request, of the work in its original "Plain -Vanilla ASCII" or other form. Any alternate format must include the -full Project Gutenberg-tm License as specified in paragraph 1.E.1. - -1.E.7. Do not charge a fee for access to, viewing, displaying, -performing, copying or distributing any Project Gutenberg-tm works -unless you comply with paragraph 1.E.8 or 1.E.9. - -1.E.8. You may charge a reasonable fee for copies of or providing -access to or distributing Project Gutenberg-tm electronic works -provided that: - -* You pay a royalty fee of 20% of the gross profits you derive from - the use of Project Gutenberg-tm works calculated using the method - you already use to calculate your applicable taxes. The fee is owed - to the owner of the Project Gutenberg-tm trademark, but he has - agreed to donate royalties under this paragraph to the Project - Gutenberg Literary Archive Foundation. Royalty payments must be paid - within 60 days following each date on which you prepare (or are - legally required to prepare) your periodic tax returns. Royalty - payments should be clearly marked as such and sent to the Project - Gutenberg Literary Archive Foundation at the address specified in - Section 4, "Information about donations to the Project Gutenberg - Literary Archive Foundation." - -* You provide a full refund of any money paid by a user who notifies - you in writing (or by e-mail) within 30 days of receipt that s/he - does not agree to the terms of the full Project Gutenberg-tm - License. You must require such a user to return or destroy all - copies of the works possessed in a physical medium and discontinue - all use of and all access to other copies of Project Gutenberg-tm - works. - -* You provide, in accordance with paragraph 1.F.3, a full refund of - any money paid for a work or a replacement copy, if a defect in the - electronic work is discovered and reported to you within 90 days of - receipt of the work. - -* You comply with all other terms of this agreement for free - distribution of Project Gutenberg-tm works. - -1.E.9. If you wish to charge a fee or distribute a Project -Gutenberg-tm electronic work or group of works on different terms than -are set forth in this agreement, you must obtain permission in writing -from the Project Gutenberg Literary Archive Foundation, the manager of -the Project Gutenberg-tm trademark. Contact the Foundation as set -forth in Section 3 below. - -1.F. - -1.F.1. Project Gutenberg volunteers and employees expend considerable -effort to identify, do copyright research on, transcribe and proofread -works not protected by U.S. copyright law in creating the Project -Gutenberg-tm collection. Despite these efforts, Project Gutenberg-tm -electronic works, and the medium on which they may be stored, may -contain "Defects," such as, but not limited to, incomplete, inaccurate -or corrupt data, transcription errors, a copyright or other -intellectual property infringement, a defective or damaged disk or -other medium, a computer virus, or computer codes that damage or -cannot be read by your equipment. - -1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the "Right -of Replacement or Refund" described in paragraph 1.F.3, the Project -Gutenberg Literary Archive Foundation, the owner of the Project -Gutenberg-tm trademark, and any other party distributing a Project -Gutenberg-tm electronic work under this agreement, disclaim all -liability to you for damages, costs and expenses, including legal -fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT -LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE -PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE -TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE -LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR -INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH -DAMAGE. - -1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a -defect in this electronic work within 90 days of receiving it, you can -receive a refund of the money (if any) you paid for it by sending a -written explanation to the person you received the work from. If you -received the work on a physical medium, you must return the medium -with your written explanation. The person or entity that provided you -with the defective work may elect to provide a replacement copy in -lieu of a refund. If you received the work electronically, the person -or entity providing it to you may choose to give you a second -opportunity to receive the work electronically in lieu of a refund. If -the second copy is also defective, you may demand a refund in writing -without further opportunities to fix the problem. - -1.F.4. Except for the limited right of replacement or refund set forth -in paragraph 1.F.3, this work is provided to you 'AS-IS', WITH NO -OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT -LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. - -1.F.5. Some states do not allow disclaimers of certain implied -warranties or the exclusion or limitation of certain types of -damages. If any disclaimer or limitation set forth in this agreement -violates the law of the state applicable to this agreement, the -agreement shall be interpreted to make the maximum disclaimer or -limitation permitted by the applicable state law. The invalidity or -unenforceability of any provision of this agreement shall not void the -remaining provisions. - -1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the -trademark owner, any agent or employee of the Foundation, anyone -providing copies of Project Gutenberg-tm electronic works in -accordance with this agreement, and any volunteers associated with the -production, promotion and distribution of Project Gutenberg-tm -electronic works, harmless from all liability, costs and expenses, -including legal fees, that arise directly or indirectly from any of -the following which you do or cause to occur: (a) distribution of this -or any Project Gutenberg-tm work, (b) alteration, modification, or -additions or deletions to any Project Gutenberg-tm work, and (c) any -Defect you cause. - -Section 2. Information about the Mission of Project Gutenberg-tm - -Project Gutenberg-tm is synonymous with the free distribution of -electronic works in formats readable by the widest variety of -computers including obsolete, old, middle-aged and new computers. It -exists because of the efforts of hundreds of volunteers and donations -from people in all walks of life. - -Volunteers and financial support to provide volunteers with the -assistance they need are critical to reaching Project Gutenberg-tm's -goals and ensuring that the Project Gutenberg-tm collection will -remain freely available for generations to come. In 2001, the Project -Gutenberg Literary Archive Foundation was created to provide a secure -and permanent future for Project Gutenberg-tm and future -generations. To learn more about the Project Gutenberg Literary -Archive Foundation and how your efforts and donations can help, see -Sections 3 and 4 and the Foundation information page at -www.gutenberg.org - -Section 3. Information about the Project Gutenberg Literary -Archive Foundation - -The Project Gutenberg Literary Archive Foundation is a non-profit -501(c)(3) educational corporation organized under the laws of the -state of Mississippi and granted tax exempt status by the Internal -Revenue Service. The Foundation's EIN or federal tax identification -number is 64-6221541. Contributions to the Project Gutenberg Literary -Archive Foundation are tax deductible to the full extent permitted by -U.S. federal laws and your state's laws. - -The Foundation's business office is located at 809 North 1500 West, -Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up -to date contact information can be found at the Foundation's website -and official page at www.gutenberg.org/contact - -Section 4. Information about Donations to the Project Gutenberg -Literary Archive Foundation - -Project Gutenberg-tm depends upon and cannot survive without -widespread public support and donations to carry out its mission of -increasing the number of public domain and licensed works that can be -freely distributed in machine-readable form accessible by the widest -array of equipment including outdated equipment. Many small donations -($1 to $5,000) are particularly important to maintaining tax exempt -status with the IRS. - -The Foundation is committed to complying with the laws regulating -charities and charitable donations in all 50 states of the United -States. Compliance requirements are not uniform and it takes a -considerable effort, much paperwork and many fees to meet and keep up -with these requirements. We do not solicit donations in locations -where we have not received written confirmation of compliance. To SEND -DONATIONS or determine the status of compliance for any particular -state visit www.gutenberg.org/donate - -While we cannot and do not solicit contributions from states where we -have not met the solicitation requirements, we know of no prohibition -against accepting unsolicited donations from donors in such states who -approach us with offers to donate. - -International donations are gratefully accepted, but we cannot make -any statements concerning tax treatment of donations received from -outside the United States. U.S. laws alone swamp our small staff. - -Please check the Project Gutenberg web pages for current donation -methods and addresses. Donations are accepted in a number of other -ways including checks, online payments and credit card donations. To -donate, please visit: www.gutenberg.org/donate - -Section 5. General Information About Project Gutenberg-tm electronic works - -Professor Michael S. Hart was the originator of the Project -Gutenberg-tm concept of a library of electronic works that could be -freely shared with anyone. For forty years, he produced and -distributed Project Gutenberg-tm eBooks with only a loose network of -volunteer support. - -Project Gutenberg-tm eBooks are often created from several printed -editions, all of which are confirmed as not protected by copyright in -the U.S. unless a copyright notice is included. Thus, we do not -necessarily keep eBooks in compliance with any particular paper -edition. - -Most people start at our website which has the main PG search -facility: www.gutenberg.org - -This website includes information about Project Gutenberg-tm, -including how to make donations to the Project Gutenberg Literary -Archive Foundation, how to help produce our new eBooks, and how to -subscribe to our email newsletter to hear about new eBooks. diff --git a/old/69062-0.zip b/old/69062-0.zip Binary files differdeleted file mode 100644 index a1e1e97..0000000 --- a/old/69062-0.zip +++ /dev/null diff --git a/old/69062-h.zip b/old/69062-h.zip Binary files differdeleted file mode 100644 index 9c49648..0000000 --- a/old/69062-h.zip +++ /dev/null diff --git a/old/69062-h/69062-h.htm b/old/69062-h/69062-h.htm deleted file mode 100644 index 9b18573..0000000 --- a/old/69062-h/69062-h.htm +++ /dev/null @@ -1,4208 +0,0 @@ -<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" -"http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> -<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en"> -<head> -<meta http-equiv="Content-Type" content="text/html;charset=utf-8"/> -<meta http-equiv="Content-Style-Type" content="text/css"/> -<title> - The Project Gutenberg eBook of A Bacteriological Study of Ham Souring, by C. N. Mcbryde, M. D.. -</title> -<link rel="coverpage" href="images/i_cover.jpg"/> -<style type="text/css"> - -body { - margin-left: 10%; - margin-right: 10%; -} - -h1 -{ - margin-top: 2em; margin-bottom: 2em; - text-align: center; - font-size: x-large; - font-weight: normal; - line-height: 1.6; -} - - h2,h3,h4,h5, h6{ - text-align: center; - clear: both; -} - -h5 {font-size: 1.3em; font-weight: bold;} -h6 {font-size: 1.1em;} - -.half-title { - margin-top: 2em; margin-bottom: 2em; - text-align: center; - font-size: x-large; - font-weight: normal; - line-height: 1.6; -} - -div.chapter {page-break-before: always;} -h2.nobreak {page-break-before: avoid;} - -/* Paragraphs */ - -p {text-indent: 1em; - margin-top:.75em; - text-align: justify; - margin-bottom:.75em; -} - - -.psig {text-align: right; margin-right: 2em;} -.pnb {margin-bottom: 0em;} -.hang {text-align: justify; padding-left: 1.75em; text-indent:-1.75em;} - - -hr.chap {width: 65%; margin-left: 17.5%; margin-right: 17.5%;} -hr.small {width: 25%; margin-left: 37.5%; margin-right: 37.5%;} -@media print { hr.chap {display: none; visibility: hidden;}} - -ul {font-size:.9em; list-style-type: none;} - -table { - margin-left: auto; - margin-right: auto; -} - -.brdr {border: 1px solid black; border-collapse: collapse; - font-size:.9em;} -.brdr th {border: 1px solid black;} - -.standard { font-size:.9em; border-collapse: collapse;} -td, th {padding: 3px;} - -.tdh {text-align: justify; padding-left: 1.75em; text-indent:-1.75em;} -.tdl {text-align: left;} -.tdli1 {text-align: left; padding-left: 2em;} -.tdli2 {text-align: left; padding-left: 4em;} -.tdli3 {text-align: left; padding-left: 6em;} -.tdr {text-align: right;} -.tdc {text-align: center;} -.tdct {text-align: center; vertical-align: top;} -.tdrt {text-align: right; vertical-align: top;} -.tdrb {text-align: right; vertical-align: bottom;} -.tdc_br {text-align: center; border-right: 1px solid black;} -.tdc_bb {text-align: center; border-bottom: 1px solid black;} -.tdhi3 {text-align: justify; border-left: 6em; padding-left: 8em; - text-indent:-2em;} -.tdr_brtd {text-align: right; border-right: 1px solid black; - border-top: 1px dotted black;} -.tdr_br {text-align: right; border-right: 1px solid black;} -.tdc_blr {text-align: center; border-left: 1px solid black; border-right: 1px solid black;} -.tdr_blr {text-align: right; border-left: 1px solid black; border-right: 1px solid black;} -.tdc_blrb {text-align: center; border-left: 1px solid black; border-right: 1px solid black; -border-bottom: 1px solid black;} -.tdr_blrb {text-align: right; border-left: 1px solid black; border-right: 1px solid black; -border-bottom: 1px solid black;} -.tdr_bb {text-align: right; border-bottom: 1px solid black;} -.tdc_bb {text-align: center; border-bottom: 1px solid black;} -.tdl_br {text-align: left; border-right: 1px solid black;} -.tdl_brtd {text-align: left; border-right: 1px solid black; - border-top: 1px dotted black;} -.tdr_brb {text-align: right; border-right: 1px solid black; border-bottom: 1px solid black;} - -.tdl_brb {text-align: left; border-right: 1px solid black; border-bottom: 1px solid black;} -.tdc_brb {text-align: center; border-right: 1px solid black; border-bottom: 1px solid black;} - - - -.pagenum {/* uncomment the next line for invisible page numbers */ -/* visibility: hidden;*/ - position: absolute; - left: 92%; - font-size: smaller; - text-align: right; -}/* page numbers */ - - -.blockquot { - margin-left: 5%; - margin-right: 10%; -} -.center {text-align: center;} - -.right {text-align: right;} - -.smcap {font-variant: small-caps;} - -.fs2 {font-size: 70%;} -.fs3 {font-size: 90%;} - - -/* Images */ - -img {border: none; max-width: 100%} -.caption {font-size: smaller; font-weight: bold;} - -.figcenter { - margin: auto; - text-align: center; - page-break-inside: avoid; - max-width: 100%; -} -.figleft { - float: left; - clear: left; - margin-left: 0; - margin-bottom: 1em; - margin-top: 1em; - margin-right: 1em; - padding: 0; - text-align: center; - page-break-inside: avoid; - max-width: 100%; -} -/* comment out next line and uncomment the following one for floating figleft on ebookmaker output */ -/*.x-ebookmaker .figleft {float: none; text-align: center; margin-right: 0;}*/ -.x-ebookmaker .figleft {float: left;} - - -/* Footnotes */ - -.footnotes {border: dashed 1px;} - -.footnote { - margin-left: 10%; - margin-right: 10%; - font-size: 0.9em; -} - -.footnote .label { - position: absolute; - right: 84%; - text-align: right; -} - -.fnanchor { - vertical-align: super; - font-size:.8em; - text-decoration: none; - white-space: nowrap -} - -/* Transcriber's notes */ - -.transnote { - background-color:#E6E6FA; - color: black; - font-size:smaller; - padding:0.5em; - margin-bottom:5em; - font-family:sans-serif, serif; -} - -.illowp50 {width: 50%;} -.illowp100 {width: 100%;} -.illowp20 {width: 20%;} -.illowp25 {width: 25%;} -.illowp80 {width: 80%;} - -</style> -</head> -<body> -<p style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of A bacteriological study of ham souring, by C. N. McBryde</p> -<div style='display:block; margin:1em 0'> -This eBook is for the use of anyone anywhere in the United States and -most other parts of the world 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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you -are not located in the United States, you will have to check the laws of the -country where you are located before using this eBook. -</div> - -<p style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: A bacteriological study of ham souring</p> -<p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em'>Author: C. N. McBryde</p> -<p style='display:block; text-indent:0; margin:1em 0'>Release Date: September 28, 2022 [eBook #69062]</p> -<p style='display:block; text-indent:0; margin:1em 0'>Language: English</p> - <p style='display:block; margin-top:1em; margin-bottom:0; margin-left:2em; text-indent:-2em; text-align:left'>Produced by: Charlene Taylor, Les Galloway and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive/American Libraries.)</p> -<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK A BACTERIOLOGICAL STUDY OF HAM SOURING ***</div> - - -<div class="transnote"> -<h3>Transcriber’s Notes</h3> - -<p>Obvious typographical errors have been silently corrected.</p> -<p>The cover was prepared by the transcriber and is placed in the -public domain.</p> - -</div> - -<hr class="chap"/> - - - - -<p class="right fs2">Issued March 17, 1911.</p> - -<p class="center">U. S. DEPARTMENT OF AGRICULTURE,<br /> -<small>BUREAU OF ANIMAL INDUSTRY.—<span class="smcap">Bulletin 132.</span><br /> -A. D. MELVIN,<span class="smcap">Chief of Bureau</span>.</small></p> - - -<h1>A BACTERIOLOGICAL STUDY -OF HAM SOURING.</h1> - - -<p class="center fs3">BY</p> - -<p class="center">C. N. McBRYDE, M. D.,<br /> -<span class="fs2"><i>Senior Bacteriologist, Biochemic Division</i>.</span></p> - -<div class="figcenter illowp25" id="seal" style="max-width: 15.625em;"> -<img src="images/seal.jpg" alt="Department seal"/> -</div> - - -<p class="center"><small>WASHINGTON:<br /> -GOVERNMENT PRINTING OFFICE.<br /> -1911.</small></p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="THE_BUREAU_OF_ANIMAL_INDUSTRY">THE BUREAU OF ANIMAL INDUSTRY.</h2> -</div> -<hr class="small"/> - - -<ul class="fs3"> -<li><i>Chief</i>: <span class="smcap">A. D. Melvin</span>.</li> -<li><i>Assistant Chief</i>: <span class="smcap">A. M. Farrington</span>.</li> -<li><i>Chief Clerk</i>: <span class="smcap">Charles C. Carroll</span>.</li> -<li><i>Animal Husbandry Division</i>: <span class="smcap">George M. Rommel</span>, chief.</li> -<li><i>Biochemic Division</i>: <span class="smcap">M. Dorset</span>, chief.</li> -<li><i>Dairy Division</i>: <span class="smcap">B. H. Rawl</span>, chief.</li> -<li><i>Inspection Division</i>: <span class="smcap">Rice P. Steddom</span>, chief;<span class="smcap">R. A. Ramsay</span>,<span class="smcap">Morris Wooden</span>, and -<span class="smcap">Albert E. Behnke</span>, associate chiefs.</li> -<li><i>Pathological Division</i>: <span class="smcap">John R. Mohler</span>, chief.</li> -<li><i>Quarantine Division</i>: <span class="smcap">Richard W. Hickman</span>, chief.</li> -<li><i>Zoological Division</i>: <span class="smcap">B. H. Ransom</span>, chief.</li> -<li><i>Experiment Station</i>: <span class="smcap">E. C. Schroeder</span>, superintendent.</li> -<li><i>Editor</i>:<span class="smcap">James M. Pickens</span>.</li> -</ul> - - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="LETTER_OF_TRANSMITTAL">LETTER OF TRANSMITTAL.</h2> -</div> - - -<p class="center pnb"> -<span class="smcap">United States Department of Agriculture,</span></p> -<p class="psig pnb">Bureau of Animal Industry,</p> -<p class="right"><i>Washington, D. C., November 2, 1910</i>. -</p> - -<p><span class="smcap">Sir</span>: I have the honor to transmit and to recommend for publication -as a bulletin of this Bureau a paper entitled “A Bacteriological -Study of Ham Souring,” by Dr. C. N. McBryde, senior bacteriologist -in the Biochemic Division of this Bureau.</p> - -<p>The souring of hams is a source of considerable loss in the meat-packing -industry, and the cause of this trouble has heretofore been -in doubt. Dr. McBryde’s paper presents the results of an exhaustive -study of the subject, from which it appears that he has succeeded in -discovering the true cause of the trouble. Besides a description of the -experimental work the paper discusses methods of preventing the -souring of hams and the proper disposal of those which have become -affected.</p> - -<p class="pnb"> -Respectfully,</p> -<p class="psig"><span class="smcap">A. D. Melvin</span>,<br /> -<i>Chief of Bureau</i>.</p> -<p>Hon.<span class="smcap">James Wilson</span>,<br /> -<span style="margin-left:4em"><i>Secretary of Agriculture</i>.</span></p> -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<p><span class="pagenum" id="Page_6">[Pg 6]</span></p> - -<h2 class="nobreak" id="CONTENTS">CONTENTS.</h2> -</div> - -<table class="standard" summary=""> -<tr> -<td></td> -<td class="tdr">Page.</td> -</tr> -<tr> -<td class="tdl">Introductory</td> -<td class="tdr"><a href="#Page_7">7</a></td> -</tr> -<tr> -<td class="tdl">Method of curing hams</td> -<td class="tdr"><a href="#Page_8">8</a></td> -</tr> -<tr> -<td class="tdl">Definition of souring</td> -<td class="tdr"><a href="#Page_10">10</a></td> -</tr> -<tr> -<td class="tdl">Classification of sour hams and location of sour areas</td> -<td class="tdr"><a href="#Page_10">10</a></td> -</tr> -<tr> -<td class="tdl">Method of detecting sour hams</td> -<td class="tdr"><a href="#Page_12">12</a></td> -</tr> -<tr> -<td class="tdl">Theories in regard to ham souring</td> -<td class="tdr"><a href="#Page_12">12</a></td> -</tr> -<tr> -<td class="tdl">Previous experimental work to determine cause of ham souring</td> -<td class="tdr"><a href="#Page_13">13</a></td> -</tr> -<tr> -<td class="tdl">The present experiments</td> -<td class="tdr"><a href="#Page_14">14</a></td> -</tr> -<tr> -<td class="tdli1">Media employed</td> -<td class="tdr"><a href="#Page_14">14</a></td> -</tr> -<tr> -<td class="tdli1">Method of procedure in examining hams</td> -<td class="tdr"><a href="#Page_15">15</a></td> -</tr> -<tr> -<td class="tdli1">Results of examination of sour and sound hams</td> -<td class="tdr"><a href="#Page_16">16</a></td> -</tr> -<tr> -<td class="tdli1">Histological changes in sour hams</td> -<td class="tdr"><a href="#Page_17">17</a></td> -</tr> -<tr> -<td class="tdli1">Chemical analyses of sour and sound hams</td> -<td class="tdr"><a href="#Page_18">18</a></td> -</tr> -<tr> -<td class="tdli1">Bacteriological examination of sour and sound hams</td> -<td class="tdr"><a href="#Page_20">20</a></td> -</tr> -<tr> -<td class="tdli1">Inoculation experiments with hams</td> -<td class="tdr"><a href="#Page_21">21</a></td> -</tr> -<tr> -<td class="tdli1">Probable method by which ham-souring bacillus enters hams</td> -<td class="tdr"><a href="#Page_33">33</a></td> -</tr> -<tr> -<td class="tdli2">Possibility of infection prior to slaughter</td> -<td class="tdr"><a href="#Page_33">33</a></td> -</tr> -<tr> -<td class="tdli2">Possible infection from pickling fluids</td> -<td class="tdr"><a href="#Page_34">34</a></td> -</tr> -<tr> -<td class="tdhi3">Experiment to show whether infection takes place from the curing -pickle</td> -<td class="tdrb"><a href="#Page_34">34</a></td> -</tr> -<tr> -<td class="tdli2">Possible infection through manipulation or handling</td> -<td class="tdr"><a href="#Page_35">35</a></td> -</tr> -<tr> -<td class="tdhi3">Infection from ham thermometers</td> -<td class="tdr"><a href="#Page_35">35</a></td> -</tr> -<tr> -<td class="tdhi3">Experiment to show whether hams become infected from ham -thermometers</td> -<td class="tdrb"><a href="#Page_37">37</a></td> -</tr> -<tr> -<td class="tdli3">Infection from pumping needles</td> -<td class="tdr"><a href="#Page_41">41</a></td> -</tr> -<tr> -<td class="tdli3">Infection from billhooks</td> -<td class="tdr"><a href="#Page_42">42</a></td> -</tr> -<tr> -<td class="tdli1">Biological and morphological characteristics of the ham-souring bacillus</td> -<td class="tdr"><a href="#Page_43">43</a></td> -</tr> -<tr> -<td class="tdli2">Conditions favorable to growth</td> -<td class="tdr"><a href="#Page_43">43</a></td> -</tr> -<tr> -<td class="tdli2">Growth on different culture media</td> -<td class="tdr"><a href="#Page_43">43</a></td> -</tr> -<tr> -<td class="tdli2">Morphology</td> -<td class="tdr"><a href="#Page_46">46</a></td> -</tr> -<tr> -<td class="tdli2">Spore formation</td> -<td class="tdr"><a href="#Page_46">46</a></td> -</tr> -<tr> -<td class="tdli2">Resistance to heat and chemical agents</td> -<td class="tdr"><a href="#Page_47">47</a></td> -</tr> -<tr> -<td class="tdli2">Gas production</td> -<td class="tdr"><a href="#Page_47">47</a></td> -</tr> -<tr> -<td class="tdli2">Acid production</td> -<td class="tdr"><a href="#Page_48">48</a></td> -</tr> -<tr> -<td class="tdli2">Pathogenic properties</td> -<td class="tdr"><a href="#Page_48">48</a></td> -</tr> -<tr> -<td class="tdli2">Nature of the bacillus</td> -<td class="tdr"><a href="#Page_48">48</a></td> -</tr> -<tr> -<td class="tdl">Prevention of ham souring</td> -<td class="tdr"><a href="#Page_50">50</a></td> -</tr> -<tr> -<td class="tdl">General summary and conclusions</td> -<td class="tdr"><a href="#Page_53">53</a></td> -</tr> -<tr> -<td class="tdl">Acknowledgments</td> -<td class="tdr"><a href="#Page_55">55</a></td> -</tr> -</table> - - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="ILLUSTRATIONS">ILLUSTRATIONS.</h2> -</div> - -<hr class="small"/> - -<p class="center fs3">PLATES.</p> - -<table class="standard" summary=""> -<tr> -<td></td><td></td> -<td></td> -<td class="tdr">Page.</td> -</tr> -<tr> -<td class="tdct"><span class="smcap">Plate</span></td> -<td class="tdrt"><a href="#Plate_I">I</a>. </td> -<td class="tdh">Fig. 1.—Section of muscular tissue from sound ham, showing muscle -fibers cut longitudinally; nuclei sharply defined and cross striation -distinct. Fig. 2.—Section of muscular tissue from sour ham, -showing muscle fibers cut longitudinally; nuclei undergoing disintegration and cross striation indistinct</td> -<td class="tdrb">16</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#Plate_II">II</a>. </td> -<td class="tdh">Fig. 1.—Section through muscular tissue of ham which has undergone -natural or spontaneous souring, showing distribution of -bacilli between the muscle fibers, which are cut obliquely. -Fig.2.—Section through muscular tissue of ham which has undergone -natural or spontaneous souring, showing individual bacilli between -the muscle fibers, which are cut somewhat obliquely</td> -<td class="tdrb">18</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#Plate_III">III</a>. </td> -<td class="tdh">Fig. 1.— Section through muscular tissue of artificially soured ham, showing -distribution of bacilli between the muscle fibers, which are shown -in cross section. Fig. 2.—Section through muscular tissue of -artificially soured ham, showing individual bacilli between the -muscle fibers, which are cut longitudinally</td> -<td class="tdrb">26</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#Plate_IV">IV</a>. </td> -<td class="tdh">Glucose bouillon culture in Smith fermentation tube at four days</td> -<td class="tdrb">48</td> -</tr> -<tr> -<td class="tdc" colspan="4">TEXT FIGURES.</td> -</tr> -<tr> -<td class="tdct"><span class="smcap">Fig.</span></td> -<td class="tdrt"><a href="#fig1">1</a>. </td> -<td class="tdh">Cross section through body of ham, with sour areas indicated by shading -and dotted lines</td> -<td class="tdrb">11</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#fig2">2</a>. </td> -<td class="tdh">Cross section through body of ham to show method of sampling for -chemical analysis</td> -<td class="tdrb">18</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#fig3">3</a>. </td> -<td class="tdh">Cross section through body of artificially soured ham, showing sour -areas and points at which cultures were taken</td> -<td class="tdrb">25</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#fig4">4</a>. </td> -<td class="tdh">Diagrammatic views showing construction of ham thermometer</td> -<td class="tdrb">36</td> -</tr> -<tr> -<td class="tdrt" colspan="2"><a href="#fig5">5</a>. </td> -<td class="tdh">Ham-souring bacillus (<i>Bacillus putrefaciens</i>), grown on egg-pork medium</td> -<td class="tdrb">46</td> -</tr> -</table> - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<p><span class="pagenum" id="Page_7">[Pg 7]</span></p> - -<p class="half-title">A BACTERIOLOGICAL STUDY OF HAM SOURING.</p> - -<hr class="small"/> - - -<h2 class="nobreak" id="INTRODUCTORY">INTRODUCTORY.</h2> -</div> - - -<p>The souring of hams is a matter of considerable importance to those -engaged in the meat-packing industry, and has been the occasion -of no little worry, as in even the best-regulated packing establishments -the yearly losses it entails are considerable. The subject -has given rise to much speculation on the part of those engaged in the -curing of meats, as to the cause of the trouble and how it may be -remedied, and has received considerable attention in a practical way, -but little seems to have been done in a scientific way toward determining -the cause and nature of ham souring.</p> - -<p>In a well-regulated meat-packing establishment the loss from ham -souring is usually figured at about one-tenth of 1 per cent of the total -weight of hams cured. At first thought this would seem but a small -loss, but when one reflects that in a single large packing establishment -some 3,000,000 hams are cured during the year, the loss, when figured -out, is considerable. Taking 15 pounds as the average weight of a -ham, 3,000,000 hams would represent 45,000,000 pounds of meat. -Figuring the loss from souring on the basis mentioned, the amount of -meat condemned and destroyed during the year would be 45,000 -pounds. Assuming that hams sell at an average wholesale price of -15 cents a pound, the yearly loss for a single plant which cures -3,000,000 hams a year would be nearly $7,000.</p> - -<p>While one-tenth of 1 per cent of the total weight of hams cured -would represent the loss from souring in a well-regulated establishment, -statistics obtained through Government meat inspectors show -that 0.25 per cent would more nearly represent the loss for the entire -country. During the fiscal year from July 1, 1908, to June 30, 1909, -some 670,000,000 pounds of hams were placed in cure in packing -establishments subject to Government inspection. Estimating the -loss from souring at 0.25 per cent, the total amount of meat condemned -and destroyed as sour would be 1,675,000 pounds. At 15 -cents a pound the total annual loss from ham souring in packing -houses subject to Government inspection would figure up something -over a quarter of a million of dollars.</p> - -<p>The problem of ham souring, therefore, is quite an important one -from a practical and financial standpoint; but aside from these considerations -it is also a subject of considerable scientific interest, and<span class="pagenum" id="Page_8">[Pg 8]</span> -in view of the fact that all sour meats are condemned under the Federal -regulations governing meat inspection it has seemed fitting that -this question should be made the subject of scientific investigation on -the part of the Bureau which is charged with the administration of -this inspection.</p> - -<p>The investigation reported in this paper has been conducted chiefly -along bacteriological lines, and has been confined entirely to the wet -method of curing hams, as this method is the one generally used in -American packing houses.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="METHOD_OF_CURING_HAMS">METHOD OF CURING HAMS.</h2> -</div> - - -<p>In order to make clear certain points in regard to the nature and -occurrence of ham souring and to insure a better understanding of the -experiments which are to be described later, it would seem best to -begin with a brief outline of the method of curing hams as practiced -in the larger packing establishments of the country. This description -is merely a general outline of the method of preparing hams for cure -and the method of handling hams while in cure, and deals chiefly with -those points that bear on the question of souring.</p> - -<p>After the slaughtered animal has been cleaned, scraped, eviscerated, -washed, and split down the middle, the carcass is usually -allowed to hang for an hour or so in a large room open to the outside -air, known as the “hanging floor.” This is done with a view to -getting rid of a certain amount of the body heat before the carcass is -run into the chill rooms, and effects a saving in refrigeration.</p> - -<p>The carcasses are next run into “coolers” or chill rooms, and subjected -to refrigeration with a view to ridding them entirely of their -body heat. The coolers are large rooms fitted with brine pipes and -capable of accommodating several hundred carcasses. The temperature -of the coolers when the carcasses are run in is about 32° F. -When filled, the temperature of the cooler rises to about 45° F., owing -to the heat given off from the carcasses. The temperature is then -gradually reduced to 28 or 30° F. Hog carcasses are left in the coolers -as a rule for forty-eight hours, at the end of which time they are stiff -and firm, but not frozen. The temperature of the chill rooms is -always carefully watched, thermometer readings being made every -few hours and duly recorded. The temperature of the carcasses is -always tested when they leave the chill room. In those plants provided -with a hanging floor, a certain number of the carcasses are also -tested before they are sent to the chill rooms in order to determine -the amount of heat lost on the hanging floor.</p> - -<p>The carcasses are tested by means of an especially constructed -thermometer, known as a “ham thermometer,” which has a pointed -metal protector so that it can be thrust into the body of the ham. -(See fig. 4.) The ham has been rightly selected as the proper portion<span class="pagenum" id="Page_9">[Pg 9]</span> -of the carcass at which to take the temperature, as it constitutes the -largest mass of muscular tissue in the carcass and holds the body heat -longer than any other portion. In taking the temperature, the thermometer -is thrust deep into the body of the ham so that the point of -the thermometer rests alongside or a little behind the upper portion -of the femur or middle bone, the latter being used as a guide in introducing -the thermometer. A certain number of the carcasses from -each cooler are tested in this way as a check on the refrigeration. The -inside temperature of the hams when they leave the chill rooms -should be about 34° F.</p> - -<p>The carcasses are next cut up and the hams trimmed for pickling. -In some houses the hams are given an additional chilling of 48 hours -after they are cut from the carcasses, but this is not done as a rule, -nor does it seem to be necessary.</p> - -<p>The hams are now sent to the pickling rooms, or “sweet pickle -department,” as this branch of the packing house is designated, and -here a certain number are again tested with a thermometer, as described -above. This test is carried out by the foreman in charge of the -sweet pickle department in order that he may satisfy himself that the -hams are properly chilled before they go into the pickle and as an -additional check on the refrigeration.</p> - -<p>The hams are now ready to be “pumped,” and this pumping, as -will be shown later, constitutes an important step in a successful cure. -Pumping consists in forcing a strong brine solution containing saltpeter -into the muscular tissues of the ham, and is accomplished by -means of a large, hollow, fenestrated needle connected by means of a -rubber hose with a powerful hand pump. The needle is introduced -along the bone, the latter being used as a guide.</p> - -<p>In all of the larger packing establishments two general methods of -curing hams are followed, the two methods being designated as the -“fancy” or “mild cure” and the “regular cure,” the term “cure” -being used to designate the curing period. Various trade names are -given by the different packing establishments to the hams cured by -these methods. In the fancy cure the hams are pumped in the shank -only, whereas in the regular cure they are pumped in both body and -shank. The same pumping pickle is generally used for the two cures. -It is a significant fact that the greater proportion of the “sours” are -found among the fancy or mild cure hams. This point will be discussed -farther on in connection with some experiments to be described later.</p> - -<p>The actual curing is usually carried out in large vats which hold -about 1,400 pounds of meat or some hundred hams. The hams are -packed in the vats in layers and are entirely covered with the pickling -solution or brine. A certain proportion is always observed between -the weight of the meat and the amount of the solution. The pickling -solution, or “pickle,” as it is termed, is a brine solution containing<span class="pagenum" id="Page_10">[Pg 10]</span> -saltpeter and sugar. The composition of the pickle varies somewhat -with the different packing establishments. The fancy-cure hams are -usually cured in a milder pickle, that is, one that contains less salt -and saltpeter than the pickle used in the regular cure, although in -some packing establishments the same curing pickle is used for the -two cures, the only difference being the additional pumping given the -regular-cure hams. The pickling rooms, or “cellars,” as they are -called, are held at a temperature of 34° to 36° F., and the pickling -solutions are always chilled to this temperature before being used.</p> - -<p>The hams are allowed to remain in cure for about 60 days, and -during this time are “overhauled” several times. Overhauling consists -in throwing the hams from the vat in which they are packed into -a neighboring empty vat, and then transferring the pickle to the new -vat. The pickle is not changed, and the same pickle follows the hams -through the entire curing process. The object in overhauling is to -stir up the pickle and expose fresh surfaces of the meat to its action.</p> - -<p>Hams are also cured in tierces which hold about 300 pounds of -meat. In the tierce cure, the hams are packed in the tierces, the -latter are then headed up, the pickling solution is next run in through -the bunghole, so as to fill the tierce entirely, and a wooden stopper -is finally driven into the bunghole. The tierces are rolled back and -forth across the floor on dates corresponding to the dates of overhauling -in the vat cure. The object of the rolling is to stir up the -pickle, and in this way it corresponds to overhauling in the vat cure.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="DEFINITION_OF_SOURING">DEFINITION OF SOURING.</h2> -</div> - - -<p>To the meat inspector, a sour ham is one which has a tainted or -“off” odor, that is, any odor which deviates from the normal. The -odor may be very slight, so slight that at times only the trained meat -inspector can detect it. When slight, the odor is elusive and hard to -define, but when pronounced it has a distinctly putrefactive quality. -When not very pronounced, the odor possesses, as a rule, a slightly -sour quality, chemically speaking, and at times this sour quality may -be quite marked; hence the term “sour ham,” or “sour” has originated. -In a badly soured ham—using the term “sour” in the -packing-house sense to denote any ham that is tainted—the odor -loses this sour quality and becomes distinctly putrefactive in nature.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="CLASSIFICATION_OF_SOUR_HAMS_AND_LOCATION_OF_SOUR_AREAS">CLASSIFICATION OF SOUR HAMS AND LOCATION OF SOUR AREAS.</h2> -</div> - - -<p>Sour hams are classed as “shank sours” and “body sours,” according -to the location of the souring, and these may be “light” or -“heavy.” When the souring is very pronounced, the ham is termed -a “stinker.”</p> - -<p>Souring appears to start, as a rule, around the stifle joint (femorotibial -articulation), and extends upward into the body of the ham.</p> - -<p><span class="pagenum" id="Page_11">[Pg 11]</span></p> - -<p>In quite a large proportion of the hams which are sour in the body—probably -from 40 to 50 per cent—the souring extends through to the -bone marrow of the femur or middle bone, and the sour odor is at -times more pronounced in the bone marrow than in the meat. The -odor of the bone marrow, when pronounced, is strongly suggestive of -a dissecting-room odor, and is distinctly putrefactive in quality.</p> - -<p>In the case of light body sours the sour odor is confined to a small -area immediately around the bone, and may be so slight that it is -detected only with difficulty. In such hams the bone marrow is apt -to be sweet, and it is not until the souring becomes more extensive -that the bone marrow becomes involved.</p> - -<div class="figcenter illowp100" id="fig1" style="max-width: 62.5em;"> -<img class="w100" src="images/fig1.jpg" alt=""/> -<div class="caption"><span class="smcap">Fig. 1.</span>—Cross section through body of ham, with sour areas indicated by shading and dotted lines.</div> -</div> - -<p>The distribution of the sour area in the body of a well-developed -sour is shown in figure 1.</p> - -<p>In the case of a well-developed body sour the sour area is more -pronounced near the bone, as represented in figure 1 by the shaded -area, and may extend out into the body of the ham for a variable -distance, according to the degree of souring, as represented by the -dotted lines, gradually fading off toward the margins, where it may -be imperceptible or entirely wanting.</p> - -<p>In the pronounced sours, termed “stinkers,” the odor pervades the -entire ham, and is of a distinctly putrefactive quality.</p> - -<p>In shank sours, the souring is more or less confined to the shank, -or the region about the tibio-femoral articulation, but may extend -upward into the lower portion of the body of the ham.</p> - -<p><span class="pagenum" id="Page_12">[Pg 12]</span></p> - -<h3>METHOD OF DETECTING SOUR HAMS.</h3> - - -<p>Souring is detected and located by means of a pointed metal instrument -known as a “ham trier,” which resembles a long, slightly flattened -ice pick. The trier is thrust into the ham at different points -along the bone, rapidly withdrawn, and the odor which clings to the -metal noted. The trained inspector works very rapidly, and is -able to detect even the slightest sour or off odor which might be -imperceptible to one not trained to the work. At the end of the -cure all hams are tested with the trier under the supervision of -Government meat inspectors.</p> - -<p>Hams are also given what is called the “30-day inspection” by -plant inspectors during the process of curing. An average ham -weighing from 14 to 16 pounds requires about 60 days to cure, and at -the end of 30 days a certain number of hams in each run are usually -tested to see how the cure is progressing. If no sour hams are -discovered at this inspection the packer knows that the cure is progressing -satisfactorily, and moreover he feels sure that his hams will -finish satisfactorily, for experience has taught him that souring develops -within the first four weeks of the curing period, and if his hams are -sweet at the end of this time, he can feel practically sure that no sours -will develop later on.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="THEORIES_IN_REGARD_TO_HAM_SOURING">THEORIES IN REGARD TO HAM SOURING.</h2> -</div> - - -<p>The theories as to the cause of souring are many and varied. The -majority of them are pure speculation and have no foundation upon -observed facts. A few of these theories may be enumerated to show -how wide and varied has been the speculation upon this subject.</p> - -<p>A theory which is quite prevalent among packing-house employees -attributes souring to overheating of the animal previous to slaughter, -but tests were made by driving hogs to the point of exhaustion just -prior to slaughter and curing the hams from these animals in comparison -with hams taken from animals which had been rested prior -to slaughter, with no difference in the cured product; that is, the -hams taken from overheated hogs cured equally as well as those -taken from rested hogs.</p> - -<p>Another theory attributes souring to a diseased condition of the -meat. Prior to the enforcement of the Federal regulations governing -meat inspection there might have been some ground for such a supposition, -but this theory could not hold at the present time, in view -of the thorough and efficient inspection now in force, for it can be -safely said that no diseased meat now passes the Government inspectors, -and therefore no diseased meat goes into cure in inspected houses. -In order to test this theory, however, hams were secured from a -number of condemned animals which showed various diseased conditions, -such as hog cholera, pyemia, septicemia, scirrhous chord, etc., -and these hams were cured in comparison with hams taken from<span class="pagenum" id="Page_13">[Pg 13]</span> -normal hogs. It was found that the hams taken from the diseased -hogs cured equally as well as those taken from healthy hogs. The -hams from the diseased hogs were destroyed after the experiment, as -the meat taken from diseased animals was of course not considered -fit for consumption, the object of the experiment being merely to -determine whether or not souring is caused by diseased conditions.</p> - -<p>Another theory attributes souring to imperfect or too rapid chilling -of the meat before it is put in pickle, and places the blame upon the -refrigeration. According to this theory, souring results when the -meat is chilled too suddenly, the idea being that by the rapid congealing -of the juices of the meat a coating is formed on the outside -of the ham whereby the animal heat is prevented from escaping from -the interior, leaving the meat next to the bone at a higher temperature -than the outside of the ham.</p> - -<p>In order to test this last theory, a number of hog carcasses were -run direct from the killing floor to a cooler at 28° F. and a like -number of carcasses of the same average weight which had been -allowed to stand for two hours at the outside temperature of -the air (53° F.) were placed in the same cooler. The carcasses -which had hung for two hours in the air had lost an average of -14 degrees in temperature before going to the cooler. The temperature -of the cooler rose to 29° F. after the carcasses were put -in, but was soon reduced to 28° F. and held at this temperature. -The temperatures of the hams were taken at the end of 24 hours, and -practically no difference was found in the inside temperatures of the -two lots; that is, the hams on the hot carcasses which were subjected -to a sudden chilling exhibited practically the same inside temperature -(i. e., next to the bone) as those which had cooled for two hours at -the temperature of the air before being placed in the cooler.</p> - -<p>Still another theory attributes souring to lack of penetration of the -pickling fluids, but analyses of sour and sound hams do not seem to -bear out this theory. The rate of penetration of the pickling fluids, -however, would seem to have some bearing on the subject, and this -point will be discussed later in connection with some laboratory -experiments on the inhibitory effects of sodium chlorid and potassium -nitrate.</p> - -<p>So much for the more commonly accepted theories which have -been advanced to explain ham souring.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="PREVIOUS_EXPERIMENTAL_WORK_TO_DETERMINE_CAUSE_OF">PREVIOUS EXPERIMENTAL WORK TO DETERMINE CAUSE OF -HAM SOURING.</h2> -</div> - - -<p>A review of the literature reveals but one article bearing directly -on the subject of the cause of ham souring.</p> - -<p>In June, 1908, Klein<a id="FNanchor_1" href="#Footnote_1" class="fnanchor">[1]</a> published in the London Lancet an article -on “miscured” hams. He describes a miscured ham as one which -<span class="pagenum" id="Page_14">[Pg 14]</span>has a distinctly putrid smell, and the tainted areas he describes as -varying in color from a dirty gray to a dirty green, the muscular -tissues in the strongly tainted areas being swollen and soft, or jelly-like. -From such hams he isolated a large nonmotile, nonspore-bearing, -anaerobic bacillus which he calls <i>Bacillus fœdans</i>. He cultivated the -organism on different media and obtained from the cultures a putrid -odor resembling that of the ham from which the culture was obtained, -but did not attempt to produce tainting by injecting sound hams -with the bacillus.</p> - -<div class="footnote"> - -<p><a id="Footnote_1" href="#FNanchor_1" class="label">[1]</a> Klein, E. On the nature and causes of taint in miscured hams. The Lancet, vol. 174, London, June -27, 1908.</p> - -</div> - -<p>While there can be little doubt that Klein’s bacillus was the cause -of the tainting in those hams which he examined, the proof would -certainly have been stronger had he injected sound hams with cultures -and thus proven that he could reproduce tainting experimentally -by means of his bacillus. Klein examined only dry-cured hams and -does not state the temperature at which they were cured. He fails -to offer any explanation as to how the bacillus gained entrance into -the hams.</p> - - -<hr class="chap x-ebookmaker-drop"/> - -<div class="chapter"> -<h2 class="nobreak" id="THE_PRESENT_EXPERIMENTS">THE PRESENT EXPERIMENTS.</h2> -</div> - - -<h3>MEDIA EMPLOYED.</h3> - -<p>After considerable experimentation as to a suitable culture medium -for the bacteriological study of sour hams, a modification of the “egg-meat -mixture” used by Rettger<a id="FNanchor_2" href="#Footnote_2" class="fnanchor">[2]</a> in his studies on putrefaction was -found to be the most satisfactory. This medium, which consists of -chopped meat and egg albumen, furnishes an excellent medium for -the growth of putrefactive organisms which rapidly break down the -proteids of the meat, giving rise to the characteristic odors of putrid -decomposition. Rettger used chopped beef and egg albumen, but for -the present work chopped pork was substituted for the beef, as affording -a more suitable medium for the growth of organisms accustomed -to growth in pork hams. The modified medium is prepared as follows:</p> - -<div class="footnote"> - -<p><a id="Footnote_2" href="#FNanchor_2" class="label">[2]</a> Rettger, L. F. Studies on putrefaction. Journal of Biological Chemistry, vol. 2, 1906.</p> - -</div> - -<p>A. One-half pound of lean pork, freed from excess of fat and -sinew, is finely chopped in a meat chopper, 250 cubic centimeters of -water is then added, the meat acids are neutralized with sodium carbonate, -and the mixture is heated in an Arnold sterilizer for 30 -minutes, with occasional stirring. It is then set away in a cold -place for several hours. A small amount of fat collects at the top in -the form of a fatty scum, as it is impossible to remove all of the fat -from the meat before it is chopped. The fatty scum, which hardens -upon standing in the cold, is now removed.</p> - -<p>B. The whites of three eggs are mixed with 250 cubic centimeters -of water. The mixture is rendered neutral to phenolphthalein by -means of dilute hydrochloric acid and heated for 30 minutes in the -Arnold sterilizer, with occasional stirring.</p> -<p><span class="pagenum" id="Page_15">[Pg 15]</span></p> -<p>A and B are now mixed and 2.5 grams (0.5 per cent) of powdered -calcium carbonate added. The mixture is next run into large sterile -test tubes, or sterile flasks, and sterilized in an Arnold sterilizer on -three successive days.</p> - -<p>In addition to the egg-pork mixture described above, culture tubes -of agar and bouillon prepared from pork instead of beef, with the -addition of 1 per cent of glucose, were also used; but the best results -were obtained with the egg-pork medium, as with this medium, the -early development of sour or putrefactive odors furnished a valuable -indication as to the presence of organisms capable of producing sour -or putrefactive changes in meat.</p> - - -<h3>METHOD OF PROCEDURE IN EXAMINING HAMS.</h3> - -<p>The hams were sectioned through the body, the femur, or “middle -bone,” as it is known in packing-house parlance, being cut at a point -about 1-1/2 or 2 inches below its head. A cross section of a ham thus -cut is shown in figure 1. After sectioning, the hams were subjected -to a microscopical, bacteriological, and chemical examination as -follows:</p> - -<p><i>Microscopical examination.</i>—Bits of muscular tissue, taken from -various points, were teased out in salt solution and the condition of -the muscle fibers noted. Smear preparations were also made from -bits of muscular tissue and from the bone marrow, and these were -stained and subjected to microscopical examination. Portions of -the meat were also hardened and cut into microscopic sections, which -were stained and mounted for histological and bacteriological study.</p> - -<p><i>Bacteriological examination.</i>—In the bacteriological examination -of sour hams, especial attention was directed to the detection of -anaerobic species, as it seemed reasonable to suppose that if the -changes taking place in sour hams were due to bacteria these bacteria -would in all likelihood be anaerobes (i. e., organisms which develop -in the absence of oxygen). This assumption was based upon the fact -that, as a rule, souring begins in the interior of the ham next to the -bone, and, furthermore, the hams are cured in large vats where they -are completely submerged in the pickling fluids, so that any bacteria -which develop within the bodies of the hams while they are in cure -are probably restricted to practically anaerobic conditions.</p> - -<p>Cultures were made from the interiors of the hams at various points -by first searing the cut surface thoroughly with a heavy metal spatula -and then cutting out, by means of sterile scissors and forceps, plugs -of meat about 1 cm. square. The plugs of meat were then dropped -into tubes containing the egg-pork medium and pushed down to the -bottom of the tubes, where they were held in place by the chopped -meat above; in this way conditions favorable for the development -of anaerobic organisms were obtained. In inoculating the pork-agar<span class="pagenum" id="Page_16">[Pg 16]</span> -tubes, the medium was first boiled to expel any inclosed air and cooled -to 43° to 45° C; the plugs of meat were then dropped into the tubes -and the agar rapidly solidified by plunging the tubes in cold water; -in this way the bits of meat were inclosed in the agar at the bottom -of the tubes, affording suitable conditions for anaerobic growth. -Aerobic and anaerobic plates were also made from the meat, and in -most cases bouillon tubes were also inoculated. Cultures were always -taken from the bone marrow as well as from the meat. Novy jars -were also used for obtaining anaerobic conditions in growing the cultures.</p> - -<p><i>Chemical examination.</i>—In order to determine whether the souring -was connected with or dependent upon a lack of penetration of the -pickling fluids to the interior of the meat, the hams were further subjected -to a chemical examination and the content of the meat in -sodium chlorid and potassium nitrate determined at varying depths.</p> - - -<h3>RESULTS OF EXAMINATION OF SOUR AND SOUND HAMS.</h3> - -<p>The sour hams examined were obtained from four different packing -establishments. All of the hams studied were “sweet-pickle hams” -which had not been smoked. The sour hams selected for examination -were good typical body sours, in which the sour odor was well developed, -but not of the very pronounced or putrefactive type.</p> - -<p>The sour odor in every case was found to be more pronounced next -to the bone, being usually rather more pronounced just behind the -bone, that is, on the fat side of the bone. The sour odor in each -instance was confined to an area of meat immediately surrounding -the femur and extending out through the body of the ham for a variable -distance, as shown by the dotted lines in figure 1, but in no case -did the sour odor extend all the way to the margin of the meat, nor -did it as a rule extend below the tibio-femoral articulation, the shank -proper and the bone marrow of the shank (i. e., of the tibia) being -usually sweet. The butt portion of the hams—that portion above -and behind the hitch bone (symphasis pubis)—was also sweet.</p> - -<p>Immediately after sectioning, the sour areas, as a rule, could be -readily distinguished by a difference in color. In the freshly cut hams -the muscular tissue near the bone, where the sour odor was more -pronounced, exhibited a slight but distinct grayish hue, at times having -a slight greenish tinge; in other words, the muscular tissue in the -sour areas lacked the normal bright red color of the sound meat and -was distinctly lighter in color than the surrounding tissues. Upon -exposure to air, however, the lighter, grayish, sour areas tend to -assume a reddish hue and become much less pronounced than in the -freshly cut ham. After the cut surface of the ham has been exposed -to the air for some time it may be difficult to distinguish the sour -areas by any difference in color.</p> - - -<p class="center small"> -<span class="smcap">Bul. 132, Bureau of Animal Industry, U. S. Dept. of Agriculture. <a id="Plate_I"></a>Plate I.</span></p> - -<div class="figcenter illowp80" id="pl1a" style="max-width: 50em;"> -<a href="images/pl1alge.jpg"> -<img src="images/pl1a.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 1.—Section of Muscular Tissue from Sound Ham, Showing -Muscle Fibers Cut Longitudinally; Nuclei Sharply Defined -and Cross Striation Distinct.</span></p> -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained with -hematoxylin and eosin to show histological structure.× 320.)</p></div> -</div> - -<div class="figcenter illowp80" id="pl1b" style="max-width: 50em;"> -<a href="images/pl1blge.jpg"> -<img src="images/pl1b.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 2.—Section of Muscular Tissue from Sour Ham, Showing -Muscle Fibers Cut Longitudinally; Nuclei Undergoing Disintegration -and Cross Striation Indistinct.</span></p></div> - -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained with -hematoxylin and eosin to show histological structure.× 320.)</p></div> - - -<p class="center small"> -<span class="smcap small">Bul. 132, Bureau of Animal Industry, U. S. Dept. of Agriculture. <a id="Plate_II"></a>Plate II.</span></p> - - -<div class="figcenter illowp80" id="pl2a" style="max-width: 50em;"> -<a href="images/pl2alge.jpg"> -<img src="images/pl2a.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 1.—Section Through Muscular Tissue of Ham which has -Undergone Natural or Spontaneous Souring, Showing Distribution -of Bacilli Between the Muscle Fibers, which are Cut -Obliquely. The Dark Masses Between the Muscle Fibers -Represent Clumps of Bacilli.</span></p></div> - -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained with -hematoxylin and eosin to show histological structure.× 320.)</p></div> - - -<div class="figcenter illowp80" id="pl2b" style="max-width: 50em;"> -<a href="images/pl2blge.jpg"> -<img src="images/pl2b.jpg" alt=""/></a> -<div class="caption"><p><span class="smcap">Fig. 2.—Section Through Muscular Tissue of Ham which has -Undergone Natural or Spontaneous Souring, Showing Individual -Bacilli Between the Muscle Fibers, which are Cut Somewhat -Obliquely. Nuclei have Lost Sharp Outline and Cross Striation -is Indistinct.</span></p></div> - -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained with -hematoxylin and eosin to show histological structure.× 320.)</p></div> - -<p><span class="pagenum" id="Page_17">[Pg 17]</span></p> -<p>In the sour areas near the bone the muscular tissue was distinctly -softer; that is, it broke and cut more readily than the surrounding -tissues. This was usually quite noticeable in cutting out plugs of -the meat for making cultures. In a ham which shows pronounced -souring the muscular tissues in the worst affected areas may become -quite soft and even slightly gelatinous.</p> - -<p>The sour areas, when tested with litmus paper, frequently showed -a slight but distinct alkaline reaction. When aqueous extracts of -the sour meat, however, were titrated with phenolphthalein they -were found to be acid.</p> - - -<h3>HISTOLOGICAL CHANGES IN SOUR HAMS.</h3> - -<p>In preparations made by teasing out bits of the meat in physiological -salt solution, the cross striation of the muscle fibers from the sour -areas was found to be much less distinct than in similar preparations -taken from sound portions of the meat or from sound hams. At -times it was found that the muscle fibers in the sour areas had completely -lost their cross striæ, but the longitudinal striation could still -be made out. In cases where the souring was pronounced there was -sometimes complete loss of both longitudinal and cross striation; in -these cases the muscle fibers appeared to have undergone slight swelling -and the protoplasm exhibited a finely granular appearance.</p> - -<p>In stained sections of the sour meat another striking change was -noticed in the disintegration of the nuclei of the muscle fibers, which -are at times completely broken up, appearing as bluish granular -masses in sections stained with hematoxylin and eosin.(Compare -figs. 1 and 2 of Pl. I.)</p> - -<p>In sections stained by the Gram-Weigert method to show the presence -of bacteria, a large Gram-staining bacillus was noted between -the muscle fibers in the connective-tissue elements of the muscle. -In some of the sections these bacilli were present in great numbers, -sometimes in densely packed clumps or masses, while in other sections, -or in other portions of the same section, they were only sparsely distributed -between the muscle fibers. Where the bacteria were more -numerous the histological changes in the muscle fibers, especially the -breaking down of the nuclei, were more noticeable. The intermuscular -connective tissue had apparently furnished paths of least resistance -along which the organism followed. In <a href="#Plate_II">Plate II</a>, figures 1 and -2, the bacteria are shown between the muscle fibers under low and -high power magnifications.</p> - -<p>In <a href="#Plate_II">Plate II</a>, figure 1, under the low-power magnification, the bacteria -appear as dark clumps or bands between the muscle bundles. -Under the high power they are shown following along the sarcolemma -sheaths between the muscle fibers.</p> - -<p><span class="pagenum" id="Page_18">[Pg 18]</span></p> - - -<h3>CHEMICAL ANALYSES OF SOUR AND SOUND HAMS.</h3> - -<p>In order to determine whether there was any difference in regard -to the penetration of the pickling fluids in the sour hams as compared -with sound hams, a series of four sour hams were subjected to a -chemical examination in comparison with four sound hams. All -were sweet-pickle hams and were obtained from the same packing -establishment. They were all of the same cure and the same approximate -age (i. e., length of cure) and the same approximate weight.</p> - -<p>In taking samples for chemical analysis, the following procedure -was adopted: A section about 2-1/2 inches wide was cut from the center -of the body. The two ends of this section were then trimmed off -along the lines L-M and N-O, as shown in figure 2. Beginning at the -skinned surface, four slices, A, B, C, and D, were then made, as indicated -by the dotted lines. Slice B contained the bone in each -instance. Slice D was practically all fat. Each slice was ground -separately in a meat chopper and the sample thoroughly mixed before -taking out portions for analysis.</p> - -<div class="figcenter illowp80" id="fig2" style="max-width: 50em;"> -<img src="images/fig2.jpg" alt=""/> -<div class="caption"><span class="smcap">Fig. 2.</span>—Cross section through body of ham to show method of sampling for chemical analysis. A, slice -below bone; B, bone slice; C, slice above bone; D, fat slice.</div> -</div> - -<p>As all of the hams examined were mild-cure hams, that is, had -been pumped in the shank only, the pickling fluids in order to reach -the bodies of these hams had to penetrate chiefly from the skinned -surface of the ham, as little if any penetration takes place through -the thick skin of the ham.</p> - -<p>The analyses<a id="FNanchor_3" href="#Footnote_3" class="fnanchor">[3]</a> shown in the following tables therefore indicate the -degree of penetration of the pickling fluids.</p> - -<div class="footnote"> - -<p><a id="Footnote_3" href="#FNanchor_3" class="label">[3]</a> These analyses were made by Mr. R. R. Henley, of the Biochemic Division, Bureau of Animal -Industry.</p> - -</div> -<p><span class="pagenum" id="Page_19">[Pg 19]</span></p> -<p class="center"><i>Analyses of sour hams.</i></p> - - -<table class="standard" summary=""> -<tr> -<th class="brdr tdc">No.</th> -<th class="brdr tdc">Description.</th> -<th class="brdr tdc">Slice.</th> -<th class="brdr tdc">NaCl.</th> -<th class="brdr tdc">KNO₃.</th> -</tr> -<tr> -<td></td> -<td class="tdc_blr"></td> -<td></td> -<td class="tdc_blr"><i>Per cent.</i></td> -<td class="tdc"><i>Per cent.</i></td> -</tr> -<tr> -<td class="tdr">1</td> -<td class="tdc_blr">Sour body</td> -<td class="tdc">A</td> -<td class="tdr_blr">6.18</td> -<td class="tdr">0.175</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.83</td> -<td class="tdr">.224</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">3.65</td> -<td class="tdr">.299</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">1.03</td> -<td class="tdr">.074</td> -</tr> -<tr> -<td class="tdr">2</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">5.34</td> -<td class="tdr">.174</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">3.70</td> -<td class="tdr">.150</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">2.79</td> -<td class="tdr">.174</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">1.12</td> -<td class="tdr">.012</td> -</tr> -<tr> -<td class="tdr">3</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">5.04</td> -<td class="tdr">.125</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.08</td> -<td class="tdr">.149</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">2.72</td> -<td class="tdr">.099</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">1.19</td> -<td class="tdr">.048</td> -</tr> -<tr> -<td class="tdr">4</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">7.78</td> -<td class="tdr">.250</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">5.31</td> -<td class="tdr">.100</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">4.76</td> -<td class="tdr">.200</td> -</tr> -<tr> -<td class="tdr_bb"></td> -<td class="tdc_blrb"></td> -<td class="tdc_bb">D</td> -<td class="tdr_blrb">1.96</td> -<td class="tdr_bb">.048</td> -</tr> -</table> - - -<p class="center"><i>Analyses of sound hams.</i></p> - -<table class="standard" summary=""> -<tr> -<th class="brdr tdc">No.</th> -<th class="brdr tdc">Description.</th> -<th class="brdr tdc">Slice.</th> -<th class="brdr tdc">NaCl.</th> -<th class="brdr tdc">KNO₃.</th> -</tr> -<tr> -<td></td> -<td class="tdc_blr"></td> -<td></td> -<td class="tdc_blr"><i>Per cent.</i></td> -<td class="tdc"><i>Per cent.</i></td> -</tr> -<tr> -<td class="tdr">1</td> -<td class="tdc_blr">Sound</td> -<td class="tdc">A</td> -<td class="tdr_blr">5.80</td> -<td class="tdr">0.211</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.83</td> -<td class="tdr">.188</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">3.86</td> -<td class="tdr">.221</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">1.33</td> -<td class="tdr">.063</td> -</tr> -<tr> -<td class="tdr">2</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">4.94</td> -<td class="tdr">.197</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.08</td> -<td class="tdr">.149</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">3.05</td> -<td class="tdr">.223</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">1.56</td> -<td class="tdr">.059</td> -</tr> -<tr> -<td class="tdr">3</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">5.92</td> -<td class="tdr">.173</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.29</td> -<td class="tdr">.099</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">4.12</td> -<td class="tdr">.139</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">D</td> -<td class="tdr_blr">2.32</td> -<td class="tdr">.049</td> -</tr> -<tr> -<td class="tdr">4</td> -<td class="tdc_blr">do</td> -<td class="tdc">A</td> -<td class="tdr_blr">5.53</td> -<td class="tdr">.119</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">B</td> -<td class="tdr_blr">4.89</td> -<td class="tdr">.079</td> -</tr> -<tr> -<td class="tdr"></td> -<td class="tdc_blr"></td> -<td class="tdc">C</td> -<td class="tdr_blr">4.32</td> -<td class="tdr">.099</td> -</tr> -<tr> -<td class="tdr_bb"></td> -<td class="tdc_blrb"></td> -<td class="tdc_bb">D</td> -<td class="tdr_blrb">2.19</td> -<td class="tdr_brb">.041</td> -</tr> -</table> - -<p>Taking an average of the four slices in each ham so as to get an -average for the entire ham, and comparing the sour hams with the -sound hams, we have the following comparison:</p> - - -<table class="standard" summary=""> -<tr> - -<td class="tdc"></td> -<td class="tdc"></td> -<td class="tdc">NaCl.</td> -<td class="tdc">KNO₃.</td> -</tr> -<tr> -<td class="tdl">Average for 4 sour hams (entire ham)</td> -<td class="tdc">per cent.</td> -<td class="tdr">3.84</td> -<td class="tdr">0.143</td> -</tr> -<tr> -<td class="tdl">Average for 4 sound hams (entire ham)</td> -<td class="tdc">do</td> -<td class="tdr">3.93</td> -<td class="tdr">.131</td> -</tr> -</table> - - -<p>These figures show practically no difference between the sour and -the sound hams as regards the sodium chlorid and potassium nitrate -content of the entire ham.</p> - -<p>If, now, we compare the bone slices—and these afford really a -better basis for comparison, as in sour-body hams the souring is -always more pronounced around the bone—we have the following -figures:</p> - -<table class="standard" summary=""> -<tr> -<td class="tdc"></td> -<td class="tdc"></td> -<td class="tdc">NaCl.</td> -<td class="tdc">KNO₃.</td> -</tr> -<tr> -<td class="tdl">Average for 4 sour hams (bone slice)</td> -<td class="tdc">per cent.</td> -<td class="tdr">4.48</td> -<td class="tdr">0.155</td> -</tr> -<tr> -<td class="tdl">Average for 4 sound hams (bone slice)</td> -<td class="tdc">do</td> -<td class="tdr">4.52</td> -<td class="tdr">0.129</td> -</tr> -</table> - - -<p>Here, again, we find no essential difference between the sour and -the sound hams, and we must conclude from these analyses that -souring does not depend upon or result from a lack of penetration -of the pickling fluids.</p> - -<p><span class="pagenum" id="Page_20">[Pg 20]</span></p> - -<p>It seems probable that in mild-cure hams, which are pumped in the -shank only, the souring begins in the upper portion of the shank and -extends upward along the bone into the body of the ham, and that -it takes place before the pickling fluid has penetrated to the interior -of the ham. When the pickling fluid reaches the interior of the ham -it tends to inhibit the souring, which, as will be shown later, is due -to the development of bacteria within the bodies of the hams. The -growth of the bacteria, however, within the bodies of the hams and -the histological changes in the muscle fibers do not seem to interfere -with the penetration of the pickling fluids.</p> - - -<h3>BACTERIOLOGICAL EXAMINATION OF SOUR AND SOUND HAMS.</h3> - -<p>In all of the sour hams which were examined bacteriologically a -large anaerobic bacillus was found to be constantly present. From -several of the hams this bacillus was obtained in pure culture; that is, -it was the only organism present in cultures made from the sour -meat and from the bone marrow of the femur. Such cultures, when -held at room temperature, gave, at three days, a sour-meat odor -exactly resembling that obtained from sour hams.</p> - -<p>In many of the sour hams other bacteria were found in association -with the anaerobic bacillus noted above. These other bacteria, however, -were not constant, being sometimes present and sometimes -absent. Among the other bacteria noted in the sour hams, the -following forms occurred most frequently:</p> - -<p>1. A nonmotile, gram-positive bacillus, measuring from 1.5 to 4 -microns in length by 0.5 micron in breadth, sometimes in chains and -filaments.</p> - -<p>2. A small, nonmotile, gram-negative bacillus, about the size of -<i>Bacillus coli</i> and usually in pairs.</p> - -<p>3. A large micrococcus.</p> - -<p>Sometimes one and sometimes all of these bacteria were present -in a given ham. They were encountered most frequently in hams -which had been pumped in both body and shank, and were probably -ordinary pickle bacteria. They were not strict anaerobes, but -belonged to the class of facultative or optional anaerobes; that is, -organisms which will grow either with or without free oxygen. -These bacteria were isolated and grown on the egg-pork medium, -but failed to give any characteristic sour or putrefactive odors, and -were therefore discarded.</p> - -<p>A series of sound hams, all of them of mild cure—that is, hams -which had been pumped in the shank only—were also examined -bacteriologically. In examining these hams cultures were taken -at varying depths, beginning at the skinned surface and going backward -toward the fat. Cultures were also taken from the bone -marrow of the femur. In the cultures taken near the skinned<span class="pagenum" id="Page_21">[Pg 21]</span> -surfaces the ordinary pickle bacteria were obtained, but these did -not, as a rule, extend beyond a depth of 3 centimeters below the -skinned surface. The cultures taken from the deeper portions of -the hams and from the bone marrow of the femur were entirely -negative—that is, failed to show any growth—and the anaerobic -bacillus noted in the sour hams was not encountered in any of the -cultures made from these hams.</p> - -<p>The anaerobic bacillus isolated from the sour hams was found -to correspond in morphology with the organism noted in the microscopic -sections made from the muscular tissue. In view of this -fact and the fact that it was constantly present in the sour hams -examined, and was capable of producing in egg-pork cultures a -sour-meat odor of the same nature as that obtained from sour hams, -this organism was subjected to further study and experimentation.</p> - - -<h3>INOCULATION EXPERIMENTS WITH HAMS.</h3> - -<p>The experiments which follow were conducted at two different -packing establishments in one of the larger packing centers of the -country. The officials at each of these establishments showed -great interest in the experiments and were most courteous and -obliging in supplying the necessary materials.</p> - -<p>The first question to be decided was whether the bacillus isolated -from sour hams was actually capable of causing ham souring. The -bacillus in question had, when cultivated on the egg-pork medium, -given rise to a sour odor similar to that obtained from sour hams, -but this was not regarded as proof positive that the organism was the -actual cause of souring in hams. The proper way to decide this -point seemed to be to inoculate hams with the bacillus and then -subject these hams to the regular method of cure and see whether -they became sour, just as the pathogenic properties of a disease-producing -organism are determined by the inoculation of experiment -animals. The first two experiments which follow were designed -to decide this point.</p> - -<p>It was regarded as important to conduct similar experiments -at two different establishments, in order to determine whether the -same results would be obtained under the somewhat different conditions -imposed by different methods of cure. The two experiments -which follow were carried out, therefore, at different establishments.</p> - - -<h6><i>Experiment I.</i></h6> - -<p>In carrying out this experiment four tierces of hams were “put -down” or “packed”—that is, placed in cure. Two of the tierces -were given the fancy or mild cure and two the regular or stronger cure. -The hams in two of the tierces, one mild and one regular cure, were -injected with a culture suspension of the bacillus; the other two tierces -were not injected with culture and were put down to serve as checks on<span class="pagenum" id="Page_22">[Pg 22]</span> -the cure. Hams weighing from 12 to 14 pounds were used for the mild -cure, while for the regular cure hams weighing from 14 to 16 pounds -were used. This was in accordance with the general rule which prevails -in packing houses, the lighter hams being subjected to the mild -cure and the heavier hams to the regular cure. The only difference -between the mild and the regular cure in this experiment lay in the -pumping. The hams which were given the mild cure were pumped -in the shank only, while those given the regular cure were pumped -in the body as well as in the shank.</p> - -<p>All of the hams had received the usual 48-hour chill. They were -all pumped with the same pumping pickle and cured in the same -curing pickle, and were in cure for the same length of time. The -pumping and curing pickles used were the regular pumping and -curing pickles of the establishment at which the experiment was -carried out, and the hams were cured in accordance with the fancy -and regular cures as practiced at this establishment.</p> - -<p>The hams were packed in new tierces which had been thoroughly -scalded with boiling water. The tierces were held in a curing room -which was kept at an average temperature of from 34° to 36° F., -the temperature occasionally going as high as 38° and 40° F., but -never above 40° F. The hams were left in cure for about 70 -days, which is a little longer than the usual cure. The tierces were -rolled three times during the cure. At the end of the cure the hams -in all four tierces were carefully tested by an expert meat inspector, -who knew nothing of the treatment which the hams had received.</p> - -<p>The hams in two of the tierces were inoculated with a culture -suspension prepared as follows: Ten tubes of egg-pork medium, each -tube containing approximately 10 cubic centimeters of the medium, -were inoculated with the bacillus and held at room temperature -(20° to 25° C.) for six days. The cultures were then filtered through -sterile gauze into a large sterile flask; this was done in order to -remove the particles of meat, which might otherwise have clogged -the syringes used in inoculating the hams. In transferring the contents -of the culture tubes to the filter the tubes were washed out -with sterile physiological salt solution (0.6 per cent sodium chlorid), -and the meat particles on the filter were afterwards washed with -the salt solution, a sufficient quantity of the latter being used to -bring the total volume of filtrate to 400 cubic centimeters. A -microscopic preparation from the filtrate showed the organisms in -large numbers, with an occasional rod showing a large terminal -spore. This suspension was used for the injection of 40 hams, each -ham being given 10 cubic centimeters, or the equivalent of 2.5 cubic -centimeters of the original culture. The hams were injected with the -culture suspension by means of a sterile syringe carrying a long 5-inch -needle. The needle was thrust well into the body of the ham at a -point near the upper end of the middle bone or femur, the latter<span class="pagenum" id="Page_23">[Pg 23]</span> -being used as a guide in inserting the needle and the injection being -made into the tissues just behind and a little to one side of the -upper end of the femur.</p> - -<p>The details of the experiment were as follows:</p> - -<div class="blockquot"> - -<p><i>Tierce No. 1 (fancy cure).</i>—This tierce contained 20 hams weighing from 12 to 14 -pounds each. These hams were pumped in the shank only. Immediately after -pumping they were injected with 10 cubic centimeters each of the liquid culture -or suspension described above. After injection the hams were immediately packed -in the tierce, which was then headed up, filled with the regular curing pickle, and -placed in cure.</p> - -<p>Result: When tested at the end of the cure all of the hams in this tierce save one -were found to be sour. In 10 of them the souring was very marked throughout the -body of the ham and extended into the shank as well. In six the souring was very -marked in the body of the ham, but did not extend into the shank. In three there -was slight but well-marked souring in the body of the ham with no souring in the -shank, and one remained sweet. The probable explanation of the variation in -the degree and the extent of the souring will be discussed later. The bone marrow -of the femur or middle bone was tested in all of the hams and found to be sour in -18. In one of the hams which showed only slight souring in the body the souring -did not extend through to the bone marrow, and in the ham which remained sweet -the bone marrow was also sweet. The fact that one ham in this tierce remained -sweet was in all likelihood due to an oversight in making the inoculations. In making -the inoculations the hams were spread out in a row on a table by a packing-house -assistant, who removed the hams as soon as they were inoculated and placed them in -tierces; and it is more than probable that the assistant removed one of the hams before -it was inoculated in the interval when the writer was busy filling the syringe for -the next inoculation.</p> - -<p><i>Tierce No. 2 (fancy cure).</i>—This tierce contained 20 hams of the same average weight -as the preceding. They were pumped in the shank only, but were not injected with -culture, being put down to serve as checks on the hams in tierce No. 1. These hams, -therefore, were subjected to exactly the same cure and were held under exactly the -same conditions as those in tierce No. 1, the only difference being that the hams in -this tierce were not injected with culture.</p> - -<p>Result: When tested at the end of the cure all of the hams in this tierce were found -to be perfectly sound and sweet, showing that the curing in this instance was properly -carried out and that the souring of the hams in tierce No. 1 was undoubtedly due to -the injections of culture which they received.</p> - -<p><i>Tierce No. 3 (regular cure).</i>—This tierce contained 20 hams weighing from 14 to -16 pounds each. These hams were pumped in the shank and also in the body. Immediately -after pumping they were each injected in the same manner as those in tierce -No. 1 with 10 cubic centimeters of culture. The hams were then packed in tierce and -placed in cure.</p> - -<p>Result: At the end of the cure 9 of the hams were found to be sour, while 11 -remained sweet. Of the 9 hams which became sour, 1 showed very pronounced souring -in the body and in the shank as well, 3 showed very pronounced souring in the -body, 1 showed pronounced souring in the body, and 4 slight souring in the body. -The bone marrow of the femur was tested in all of the sour hams and was found to be -sour in 7. In 2 of the sour hams which showed slight souring in the body the souring -noted in the meat had not extended through to the bone marrow.</p> - -<p><i>Tierce No. 4 (regular cure).</i>—This tierce contained 20 hams of the same average weight -as those in tierce No. 3, and, like the latter, were pumped in both shank and body, but -were not injected with culture. This tierce was put down to serve as a check on -tierce No. 3 and was held under exactly the same conditions, the only difference being -that these hams were not injected with culture.</p> - -<p><span class="pagenum" id="Page_24">[Pg 24]</span></p> - -<p>Result: At the end of the cure the hams were carefully tested and all were found to -be perfectly sound and sweet.</p> -</div> - - -<p class="center"><i>Results of Experiment I.</i></p> - -<table class="standard" summary=""> -<tr> -<th class="tdc brdr" rowspan ="2">No. of tierce.</th> -<th class="tdc brdr" rowspan ="2">Number<br />of hams.</th> -<th class="tdc brdr" rowspan ="2">Average<br />weight of hams<br /><i>Pounds.</i></th> -<th class="tdc brdr" rowspan ="2">Cure.</th> -<th class="tdc brdr" rowspan ="2">How pumped.</th> -<th class="tdc brdr" rowspan ="2">Treatment.</th> -<th class="tdc brdr" colspan="2">Condition at end of cure.</th> -</tr> -<tr> -<th class="tdc brdr">Number of sour hams</th> -<th class="tdc brdr">Percentage of sour hams</th> -</tr> -<tr> -<td class="tdr_br"> 1</td> -<td class="tdr_br">20</td> -<td class="tdr_br">12-14</td> -<td class="tdr_br">Fancy</td> -<td class="tdr_br">Shank only</td> -<td class="tdr_br">Each ham injected -with 10 c. c. of culture.</td> -<td class="tdr_br">19</td> -<td class="tdr_br">95</td> -</tr> -<tr> -<td class="tdr_br"> 2</td> -<td class="tdr_br">20</td> -<td class="tdr_br">12-14</td> -<td class="tdr_br">do</td> -<td class="tdr_br">do</td> -<td class="tdr_br">Not injected with culture; -check on tierce 1.</td> -<td class="tdr_br">0</td> -<td class="tdr_br">0</td> -</tr> -<tr> -<td class="tdr_br"> 3</td> -<td class="tdr_br">20</td> -<td class="tdr_br">14-16</td> -<td class="tdr_br">Regular</td> -<td class="tdr_br">Shank and body</td> -<td class="tdr_br">Each ham injected -with 10 c. c. of culture.</td> -<td class="tdr_br">9</td> -<td class="tdr_br">45</td> -</tr> -<tr> -<td class="tdr_brb"> 4</td> -<td class="tdr_brb">20</td> -<td class="tdr_brb">14-16</td> -<td class="tdr_brb">do</td> -<td class="tdr_brb">do</td> -<td class="tdr_brb">Not injected with culture; -check on tierce 3.</td> -<td class="tdr_brb">0</td> -<td class="tdr_brb">0</td> -</tr> -</table> - -<p>Three hams from each tierce were selected for bacteriological and -histological examination. From tierces 1 and 3, which contained -the injected hams, three of the most pronounced “sours” were -selected from each tierce. In examining the hams bacteriologically -the following method was adopted: The hams were sectioned near -the center of the body and the larger or butt end turned up so as to -expose the cut surface. A cross section of a ham thus cut is shown -in figure 3.</p> - -<p>Cultures were taken at the points indicated by the numbers and -from the exposed bone marrow of the femur by first searing the surface, -and then taking out plugs of the meat or marrow by means of -sterile instruments. The plugs of meat or marrow were dropped -into tubes containing egg-pork medium and pushed to the bottom of -the tubes by means of a sterile platinum wire. In the cultures made -from the sour hams from tierces 1 and 3, which were injected with -culture, the bacillus with which these hams were injected was found -in practically every culture, although it was sometimes absent in -the cultures taken at points near the skinned surfaces of the hams -(i. e., at points 1, 4, and 5 in fig. 3). In the cultures taken from the -meat, the bacillus was not always present in pure culture, but this is -not to be wondered at when we remember that the pickling fluids -often contain large numbers of bacteria of various kinds, and these, -of course, find their way into the hams in the pickling fluids. Especially -is this true of the hams which are pumped in the body, where -bacteria are actually pumped into the bodies of the hams in the -pumping pickle. In the case of hams which are not pumped in -the body, the pickle bacteria do not appear to penetrate the body of -the ham to any great depth.</p> - -<p><span class="pagenum" id="Page_25">[Pg 25]</span></p> - -<p>In figure 3 the plus signs after the figures represent the distribution -of the sour-ham bacillus in one of the hams from tierce 1, and this -may be taken as a typical example of the other sour hams which were -examined in this experiment. It should be explained that the -shaded areas are not intended to represent the actual limits of souring, -but simply the areas in which the sour odor was most pronounced -and from which it could be readily obtained with the trier. In -comparing the regular and mild cure hams, it was found that the -areas of souring as defined with the trier were more restricted in the -regular cure hams, and this was undoubtedly due to the additional -pumping which these hams received, whereby the growth of the -bacillus was partially inhibited.</p> - - -<div class="figcenter illowp100" id="fig3" style="max-width: 62.5em;"> -<img src="images/fig3.jpg" alt=""/> -<div class="caption"><p class="hang"><span class="smcap">Fig. 3.</span>—Cross section through body of artificially soured ham, showing sour areas and points at which -cultures were taken. Darker shading indicates sour area in hams pumped in body and shank; light -shading indicates sour area in hams pumped in shank only; figures indicate points at which cultures -were taken; plus signs indicate presence of bacillus; minus sign indicates absence of bacillus; X indicates -point of inoculation.</p> -</div> -</div> - -<p>It will be noticed that the sour-ham bacillus was present in cultures -taken at points outside the shaded areas, indicating that the -organism had extended generally throughout the bodies of the hams. -As the hams were inoculated at a point just to one side of and a -little behind the femur (i. e., at the point X in the figure), the presence -of the bacillus generally throughout the hams would indicate -a very extensive multiplication of the original bacilli with which the -hams were injected. In view of the fact that the bacillus in question -is nonmotile, the spread of the bacilli throughout the hams must -result simply from subdivision and growth by extension, and in -spreading throughout the hams the bacilli appear to follow along the -connective tissue bands which afford paths of least resistance. In the -cultures made from the bone marrow the bacillus was recovered in<span class="pagenum" id="Page_26">[Pg 26]</span> -pure culture from each of the hams examined, and it is probable that -the bacillus finds its way into the bone marrow from the meat by -following along the small arteries which pass through the bone. The -fact that the bacillus was found in pure culture (i. e., uncontaminated) -in the cultures made from the bone marrow is explained probably -by its capacity for growth by extension, and also by the fact that the -pickling solutions probably do not reach the bone marrow until late -in the curing and then only to a limited extent. The bacteria which -ordinarily occur in pickling fluids are not strict anaerobes and are not -placed under the most suitable conditions for growth when they -reach the interior of the ham, for it seems probable that in the interior -of hams which are totally submerged in pickling fluids the amount -of available oxygen must be extremely small. The ordinary pickle -bacteria, therefore, would not multiply as rapidly in the interior of -the hams and would not find their way into the bone marrow as -soon as would a strictly anaerobic organism.</p> - -<p>Pure cultures of the sour-ham bacillus, recovered from the meat -and bone marrow of the injected hams, were compared with cultures -of the original bacillus used for inoculating the hams, and -were found to be identical. Furthermore, the bacillus with which -the hams were injected was recovered from the injected hams at -points far removed from the original point of injection, showing that -the organism had multiplied and extended throughout the bodies of -the hams and that it was clearly responsible for the souring which -the hams had undergone.</p> - -<p>Sound hams from tierces 2 and 4 were examined bacteriologically -in the same manner as the injected hams, and some of the cultures -showed the ordinary pickle bacteria, but in not a single instance did -egg-pork cultures yield a sour odor, and in no case could the sour-ham -bacillus be demonstrated in any of these hams.</p> - -<p>Microscopic sections and teased preparations of the muscle fibers -in salt solution were prepared from several of the sour hams in this -experiment, and these preparations showed the same histological -changes and the same distribution of bacilli as noted in the natural -sours.</p> - -<p>In <a href="#Plate_III">Plate III</a>, figures 1 and 2, sections are shown of artificially soured -hams, that is, hams which were artificially soured by injections of culture; -and if these figures be compared with the sections made from -hams which had undergone spontaneous souring (see Pl. II, figs. 1 and -2) the similarity in the form and distribution of the bacilli will be at -once apparent.</p> - - -<p class="center small"> -<span class="smcap">Bul. 132, Bureau of Animal Industry, U. S. Dept. of Agriculture. <a id="Plate_III"></a>Plate III.</span></p> - -<div class="figcenter illowp80" id="pl3a" style="max-width: 50em;"> -<a href="images/pl3alge.jpg"> -<img src="images/pl3a.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 1.—Section Through Muscular Tissue of Artificially Soured -Ham, Showing Distribution of Bacilli Between the Muscle -Fibers, which are Shown in Cross Section. The Dark Lines and -Masses Between the Muscle Fibers Represent Clumps of -Bacilli.</span></p></div> - - -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained by -the Gram-Weigert method to show bacteria. × 85.)</p></div> - - -<div class="figcenter illowp80" id="pl3b" style="max-width: 50em;"> -<a href="images/pl3blge.jpg"> -<img src="images/pl3b.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 2.—Section Through Muscular Tissue of Artificially Soured -Ham, Showing Individual Bacilli Between the Muscle Fibers, -which are Cut Longitudinally.</span></p></div> -</div> - -<p class="center small">(Pen-and-ink drawing made with camera lucida from section stained by -the Gram-Weigert method to show bacteria. × 320.)]</p> - -<p><i>Summary and discussion of Experiment I.</i>—Comparing tierces 1 -and 2, where the hams were pumped in the shank only, the only -difference being that the hams in tierce 1 were inoculated with culture -while those in tierce 2 were not, we find that in tierce 1 nineteen out -of twenty, or 95 per cent, of the hams became sour, whereas in tierce 2 -all of the hams remained sweet. In view of the fact that these tierces -were held under exactly the same conditions, we must conclude that -the souring of the hams in tierce 1 was due to the injection of culture -which they received.</p> - -<p>Comparing tierces 3 and 4, where the hams were pumped in both -shank and body, the hams in tierce 3 being injected with culture -while those in tierce 4 were not, we find that in tierce 3 nine out of -twenty, or 45 per cent, of the hams became sour, whereas in tierce 4 all -of the hams remained sweet. As the conditions of cure were the same -for all four tierces, we must again conclude that the souring of the -hams in tierce 3 was directly attributable to the injections of culture -which they received.</p> - -<p>If now we compare tierces 1 and 3, the two tierces which were -injected with culture, we find that in the case of tierce 1, where the -hams were pumped in the shank only, 95 per cent became sour; -whereas in the case of tierce 3, where the hams were pumped in both -shank and body, only 45 per cent became sour. In other words, the -percentage of souring in those hams which were pumped in the body -as well as in the shank was 50 percent less than in those hams which -were pumped in the shank only. Inasmuch as the only difference -in the treatment accorded tierces 1 and 3 lay in the additional -pumping given the hams in tierce 3, we must conclude that the -marked diminution in the percentage of souring in the case of tierce -3 was undoubtedly due to the additional pumping which these hams -received, the hams being saturated at the start with the pumping -pickle. It will be shown later that both sodium chlorid and potassium -nitrate exert an inhibitory effect upon the bacillus with which the -hams were injected, which directly bears out the foregoing conclusion.</p> - -<p>In tierces 2 and 4, the two check tierces which were not injected -with culture, all of the hams were sweet at the end of the cure, showing -that the conditions under which the experiment was carried out were -entirely favorable to a successful cure.</p> - -<p>The sour odor obtained from the artificially soured hams in this -experiment was pronounced by the meat inspector who tested the -hams, and who was entirely unaware of the treatment they had -received, to be identical with the usual sour odor which characterizes -hams that have undergone spontaneous souring; in other words, -there was no difference in odor between these artificially soured hams -and natural sours.</p> - -<p>With regard to the variation in the degree and the extent of the -souring exhibited by the individual hams in the two inoculated -tierces, where some of the hams showed pronounced souring throughout -the body and shank, while others which had been injected with -the same amount of culture showed only slight souring in the body,<span class="pagenum" id="Page_28">[Pg 28]</span> -several factors must be considered, viz:(1) Differences in the reaction -of the meat of the individual hams which may have exerted an influence -on the growth of the bacteria with which the hams were injected. -(2) Variations in the texture of the muscle fibers and connective -tissue of the individual hams, permitting in some cases a more rapid -and thorough penetration of the pickling fluids to the interior of the -hams, whereby the inhibitory effect of the sodium chlorid and the -potassium nitrate on the bacteria would come into play earlier. -(3) Variations in pumping, whereby more of the pickling solution was -forced into some of the hams than into others. Probably all three of -these factors would have to be taken into account in explaining the -variation in the degree and extent of the souring exhibited by the -injected hams.</p> - -<p>With regard to the souring of the bone marrow, we find that of -nineteen sour hams in tierce 1 eighteen showed sour marrows, while -in tierce 3 nine sour hams showed seven sour marrows. The high -proportion of marrow sours is not surprising when it is recalled that -of the nineteen sour hams in tierce 1 the meat was markedly sour in -sixteen, while of the nine sour hams in tierce 3 the meat was markedly -sour in five. In the case of the four sour hams in tierce 3 -which showed slight souring in the body, two of these showed sour -marrows, while in two the marrows were sweet. In this experiment -the percentage of sour hams showing sour marrows corresponds -with the percentage of marrow-sour hams found in the packing -house, where, as has been pointed out before, a ham which is markedly -sour in the body will practically always show sour marrow, -while in hams which show only slight souring in the body the marrow -is involved in about 50 per cent of the cases.</p> - - -<h6><i>Experiment II.</i></h6> - -<p>This experiment was essentially a repetition of Experiment I, but -was carried out at a different packing establishment and under somewhat -different conditions.</p> - -<p>Two lots of hams were injected with a culture suspension of the -bacillus at different stages of the cure, or rather at different stages in -the preparation for cure, i. e.,(1) on the hanging floor, previous to -chilling, and (2) after chilling and pumping and immediately before -packing. Three tierces, each containing 20 hams, were put down. -Two of the tierces contained the hams injected with culture, while -the third tierce contained check hams which had not been treated -with culture. Half of the hams in each tierce were pumped -in the shank, while the other half were pumped in both body and -shank. The same pumping and curing pickles were used for all three -tierces, and were the regular pumping and regular curing pickles of -the establishment at which the experiment was carried out. The<span class="pagenum" id="Page_29">[Pg 29]</span> -hams used were all 14 to 16 pounds in weight and were subjected to -the usual 48-hour chill with an additional chill of 48 hours after they -were cut from the carcass. They were packed in tierces which had -been thoroughly scrubbed and cleaned with boiling water. The -tierces were held in a pickling room at a temperature of 33° to 36° F., -the temperature never rising above 36° F., and were rolled three -times during the curing period. The hams were in cure for about -eighty days. At the end of the cure the hams were carefully tested by -a trained meat inspector, who knew nothing of the treatment they -had received.</p> - -<p>The culture suspension was prepared from 20 tubes of egg-pork -medium in the same manner as that used in Experiment I, the cultures -being diluted with sufficient salt solution to give 400 cubic centimeters -of suspension. The cultures from which the suspension was prepared -had grown at room temperature for ten days. The suspension was -examined microscopically and showed large numbers of the bacilli in -the form of filaments or long chains, with many of the individual -organisms showing large terminal spores. The hams were injected -with the culture suspension in the same manner as those in Experiment -I.</p> - -<p>The details of the experiment were as follows:</p> - -<div class="blockquot"> - -<p><i>Tierce No. 1.</i>—Contained 20 hams, each ham being injected with 20 cubic centimeters -of the suspension or the equivalent of 10 cubic centimeters of the original -culture. The hams were injected while on the hanging floor, before they had been -cut from the carcasses and previous to chilling. The carcasses were still quite warm—that -is, had lost but little of their body heat when the injections were made. The -carcasses, which had been carefully tagged, were then run into coolers and given -the usual 48-hour chill, after which the hams were severed from the carcasses and -given an additional 48-hour chill in accordance with the custom of the packing -house at which the experiment was carried out. The hams were next pumped with -regular pumping pickle, 10 being pumped in both body and shank and 10 in shank -only. They were finally packed in a tierce, which was then headed up, filled with -regular curing pickle, and placed in cure.</p> - -<p>Result: When tested at the end of the cure it was found that the 10 hams which -were pumped in the shank only were all sour. In each of them the souring extended -throughout the entire ham, in the shank as well as in the body, and was very pronounced, -so much so that they were characterized as “stinkers” by the meat inspector -who assisted in testing them. The bone marrow of the femur or middle bone was -sour in all of these hams. Of the 10 hams which were pumped in both body and -shank 7 showed well-marked souring throughout the body, but the souring did not -extend into the shank. The bone marrow of the femur was found to be sour in 6 of -these hams, while in 1 the souring had not extended through to the bone marrow.</p> - -<p><i>Tierce No. 2.</i>—Contained 20 hams which were chilled and pumped in exactly the -same manner as those in tierce No. 1. These hams were injected with culture after -they had been chilled and pumped, or just before they were placed in cure. The -hams in this tierce, therefore, were injected with culture four days later than those -in tierce 1. The hams were injected with a bacterial suspension prepared in the -same manner as that used for tierce 1, except that the egg-pork cultures from which -the suspension was prepared were 7 days instead of 10 days old. Each ham was<span class="pagenum" id="Page_30">[Pg 30]</span> -injected with 20 cubic centimeters of the suspension or the equivalent of 10 cubic -centimeters of the original culture. The hams were injected in the same manner as -those in tierce 1.</p> - -<p>Result: When tested at the end of the cure, it was found that of the 10 hams which -were pumped in the shank all were sour; in 8 of these the souring was very marked -throughout the body of the ham and extended into the shank; in all of these hams -the souring had extended through to the bone marrow of the middle bone or femur. -Of the 10 hams which were pumped in both body and shank 6 were sour in the body. -These hams were classed by the meat inspector who examined them as “light body -sours,” and in none of them did the souring extend into the shank or through the -bone into the bone marrow of the femur.</p> - -<p><i>Tierce No. 3.</i>—Contained 20 hams which were chilled and pumped in the same -manner as those in the two preceding tierces. These hams were not injected with -culture and were put down to serve as checks on the cure. In other words, they -were pumped with the same pickling fluids, were subjected to exactly the same cure, -and were held under precisely the same conditions as those in the preceding tierces, -the only difference being that the hams in this tierce were not injected with culture.</p> - -<p>Result: When tested at the end of the cure, all of the hams in this tierce were found -to be perfectly sound and sweet.</p> -</div> - - -<p class="center"><i>Results of Experiment II.</i></p> - - -<table class="standard" summary=""> -<tr> -<th class="tdc brdr" rowspan="2">No. of tierce.</th> -<th class="tdc brdr" rowspan="2">Number of hams.</th> -<th class="tdc brdr" rowspan="2">Average weight<br />of hams.<br /><i>Pounds.</i></th> -<th class="tdc brdr" rowspan="2">How pumped.</th> -<th class="tdc brdr" rowspan="2">Treatment.</th> -<th class="tdc brdr" colspan="2">Condition at end of cure.</th> -</tr> -<tr> -<th class="tdc brdr">Number of<br />sour hams.</th> -<th class="tdc brdr">Percentage of<br />sour hams.</th> -</tr> -<tr> -<td class="tdr_br" rowspan="2">1</td> -<td class="tdr_br" rowspan="2">20</td> -<td class="tdr_br" rowspan="2">14-16</td> -<td class="tdl_br">10 in shank</td> -<td class="tdl_br">Each ham injected with 20 -c. c. of culture prior to chilling and pumping.</td> -<td class="tdr_br">10</td> -<td class="tdr_br">100</td> -</tr> -<tr> -<td class="tdl_br">10 in body and shank</td> -<td class="tdc_br">do</td> -<td class="tdr_br">7</td> -<td class="tdr_br">70</td> -</tr> -<tr> -<td class="tdr_brtd" rowspan="2">2</td> -<td class="tdr_brtd" rowspan="2">20</td> -<td class="tdr_brtd" rowspan="2">14-16</td> -<td class="tdl_brtd">10 in shank</td> -<td class="tdl_brtd">Each ham injected with 20 -c. c. of culture subsequent to chilling and pumping.</td> -<td class="tdr_brtd">10</td> -<td class="tdr_brtd">100</td> -</tr> -<tr> -<td class="tdl_br">10 in body and shank</td> -<td class="tdc_br">do</td> -<td class="tdr_br">6</td> -<td class="tdr_br">60</td> -</tr> -<tr> -<td class="tdr_brtd" rowspan="2">3</td> -<td class="tdr_brtd" rowspan="2">20</td> -<td class="tdr_brtd" rowspan="2">14-16</td> -<td class="tdl_brtd">10 in shank</td> -<td class="tdl_brtd">Not injected with culture</td> -<td class="tdr_brtd">0</td> -<td class="tdr_brtd">0</td> -</tr> -<tr> -<td class="tdl_brb">10 in body and shank</td> -<td class="tdc_brb">do</td> -<td class="tdr_brb">0</td> -<td class="tdr_brb">0</td> -</tr> -</table> - -<p>Four hams were selected from each tierce for bacteriological and -histological examination. From tierces 1 and 2, in which the hams -were injected with culture, 4 of the sourest hams were selected from -each tierce. Cultures were made from these hams in the same -manner as described under Experiment I and with the same result—that -is, the sour-ham bacillus was found throughout the bodies of -the hams. Microscopic sections were also prepared from these hams -and showed the same histological changes and the same distribution -of bacilli as noted for the hams in Experiment I.</p> - -<p><i>Summary and discussion of Experiment II.</i>—Comparing tierces 1 -and 2, in which the hams were injected with culture, with tierce 3, -where the hams were not injected with culture, we find that in tierce -1 seventeen hams (85 per cent) became sour and in tierce 2 sixteen -hams (80 per cent) became sour, whereas in tierce 3 all of the hams<span class="pagenum" id="Page_31">[Pg 31]</span> -were sweet. The fact that all of the hams in tierce 3, the check -tierce, were sweet indicates that the conditions were favorable for a -successful cure; and as all three tierces were cured under exactly the -same conditions, the only difference being that the hams in tierces -1 and 2 were injected with culture, whereas those in tierce 3 were not -injected with culture, we must conclude that the souring of the hams -in tierces 1 and 2 was due to the injections of culture which they -received.</p> - -<p>Comparing tierce 1 with tierce 2, we find that the hams in tierce 1 -showed more extensive souring than did those in tierce 2, this being -especially noticeable in the case of the hams which were pumped in -both body and shank. This difference in the extent or degree of souring -was probably due to the fact that the hams in tierce 1 were -injected while they were still warm and before they had lost their -animal heat, the bacterial suspension thus having a better chance to -become disseminated through the meat. The hams in tierce 2 were -injected with culture after they had been chilled, when the tissues -were more or less contracted and the conditions less favorable for the -dissemination of the suspension throughout the meat. The hams in -tierce 1 were also injected four days earlier than those in tierce 2, -and prior to pumping; and this would explain the greater difference -in the extent of the souring in the case of the hams which were -pumped in both body and shank, as in tierce 1 the bacteria had four -days in which to develop before coming in contact with the pickling -fluids, whereas in tierce 2 the bacteria were injected after the hams -were pumped with pickle and were thus brought into immediate -contact with the pickling fluids, which, as will be shown later, have a -distinct inhibitory action upon the bacillus in question. In the case -of the hams which were pumped in the shank but not in the body -there was not this difference, as in these hams the pickling fluids -must penetrate into the bodies of the hams from the outside. As it -requires some time for the pickling fluids to reach the interior of a -ham, the bacteria were thus afforded quite an interval in which to -develop before being exposed to the inhibitory action of the pickling -fluids. A chemical study of the processes involved in ham curing -has been carried out in the Biochemic Division and the approximate -rate of penetration of the curing pickle determined, and it was found -that it required about four weeks for the interior of a 10-pound ham -which had not been pumped to acquire its maximum percentage of -sodium chlorid.</p> - -<p>To recapitulate: In this experiment 40 hams were injected with -culture, half of this number being pumped in the shank only and -half in both body and shank. Of the 20 which were pumped in the -shank only, every ham without exception, or 100 per cent, became -sour. Of those which were pumped in both body and shank, 13, or<span class="pagenum" id="Page_32">[Pg 32]</span> -65 per cent, became sour. The reduction in the percentage of sours -in the last lot was clearly due to the additional pumping which these -hams received.</p> - -<p>If now we compare tierce 2 in this experiment with tierces 1 and 3 -in Experiment I—these three tierces being comparable, as they were -all injected with culture at the same stage in their preparation for -cure, that is, subsequent to chilling and pumping—we find, in the -case of the hams pumped in both body and shank, 65 per cent of -sours in Experiment II as against 45 per cent in Experiment I, and -this difference is undoubtedly due to the heavier dose of culture -used in Experiment II, where the hams were given the equivalent -of 10 cubic centimeters of egg-pork culture as against 2-1/2 cubic centimeters -in Experiment I. In the case of the hams which were -pumped in the shank but not in the body, the percentage of sours -was practically the same in the two experiments—in Experiment I -all but one of these hams became sour, while in Experiment II all of -them became sour. The degree or extent of the souring in these last -hams, however, was greater in Experiment II, a result of the heavier -injections of culture which they received.</p> - - -<h6><i>Summary of Experiments I and II.</i></h6> - -<p>Summarizing the results obtained in Experiments I and II, we find -that culture suspensions of the anaerobic bacillus isolated from sour -hams caused souring with great uniformity when injected into the -bodies of sound hams which were pumped in the shank only. In -the two experiments, 40 sound hams which were pumped in the -shank only were injected with culture suspensions of the bacillus, -with the result that 39, or 97.5 per cent, became sour during the -process of cure; and it is quite probable, as we have pointed out -before, that one of these hams was overlooked in making the inoculations, -otherwise the entire lot would have become sour.</p> - -<p>The inhibitory action of the pickling fluids upon the bacillus is -well shown in the case of those hams which were pumped in both -body and shank. Out of 40 hams which were pumped in both body -and shank, 22, or 55 per cent, became sour in the process of curing. -Inasmuch as these hams were cured under precisely the same conditions -as the hams which were pumped in the shank only, we must -conclude that the diminution in souring in these hams was undoubtedly -due to the additional pumping which they received, whereby -the bacteria with which these hams were injected were brought into -immediate contact with the strong pumping pickle and their development -thereby inhibited.</p> - -<p>In these two experiments it was proven beyond doubt that the -anaerobic bacillus isolated from sour hams was capable of producing<span class="pagenum" id="Page_33">[Pg 33]</span> -souring when introduced into the bodies of sound hams; and in view -of the fact that this bacillus was constantly present in hams which -had undergone spontaneous or natural souring, and was the only -organism that could be isolated from such hams that was capable of -producing in egg-pork cultures the characteristic sour-ham odor, the -conclusion seems justifiable that this bacillus is an undoubted cause -of the ham souring which occurs in the packing house; and the -results thus far obtained indicate that it is an important, if not the -only, factor concerned in ham souring.</p> - -<p>Having established the etiological relation of the bacillus isolated -from sour hams with ham souring, the next point to be considered -was the manner in which this bacillus finds its way into the bodies of -the hams.</p> - - -<h3>PROBABLE METHOD BY WHICH HAM-SOURING BACILLUS ENTERS HAMS.</h3> - -<p>Regarding the question of the probable method by which the ham-souring -bacillus enters hams, there were three possibilities to be taken -into consideration:(1) That the bacillus is present in the flesh of -hogs at the time of slaughter,(2) that the bacillus gains entrance -through the pickling fluids,(3) that the bacillus is introduced into -the bodies of the hams in the handling or manipulation which the -hams undergo in preparation for, or during, the process of curing.</p> - - -<h4><span class="smcap">Possibility of Infection Prior to Slaughter.</span></h4> - -<p>In order to throw some light upon this point, a number of fresh -hams—that is, hams which had been chilled but not pumped or subjected -to any other manipulation—were examined bacteriologically, -but in no case could the anaerobic bacillus which was isolated from -sour hams be detected in any of them. The fact that in certain -of the smaller packing establishments which cure their hams without -pumping the percentage of souring is extremely low would also -seem to negative this possibility, for if the bacillus which causes -souring were present in the hams at the time of slaughter, sour hams -would be as frequent at such establishments as at those establishments -which make a practice of pumping. Furthermore, a laboratory -study, biological and chemical, of the bacillus isolated from -sour hams shows that this organism belongs to the class of putrefactive -bacteria, and while such bacteria may be present in the -intestines of healthy animals, as, for example, the bacillus of Bienstock -(<i>Bacillus putrificus</i>), these bacteria do not invade the organs -and tissues of the body until after the death of the animal, and the -packing-house practice of rapidly eviscerating the hogs immediately -after slaughter would certainly preclude this possibility.</p> - -<p><span class="pagenum" id="Page_34">[Pg 34]</span></p> - - -<h4><span class="smcap">Possible Infection from Pickling Fluids.</span></h4> - -<p>With regard to the second possibility, that the bacillus finds its -way into the hams in the curing pickles, it was determined by laboratory -experiment that the addition of 3 per cent of sodium chlorid or -3 per cent of potassium nitrate to laboratory media completely -inhibits the growth of the bacillus. As the pickling solutions always -contain considerably more than these percentages of sodium chlorid -and potassium nitrate, it would be impossible for the bacillus to -multiply in the pickles. Additional laboratory experiments demonstrated, -however, that the bacillus or its spores may remain alive in -the curing pickles for at least thirty days, and it seemed possible that -the curing pickles might become contaminated at times with the -bacilli, and that the bacilli, although incapable of multiplying in the -pickles, might find their way into the bodies of the hams in the -pickling fluids. In order to throw some light upon this point, the -following experiment was carried out:</p> - - -<h5>EXPERIMENT TO SHOW WHETHER INFECTION TAKES PLACE FROM THE CURING PICKLE.</h5> - -<p>In this experiment two tierces were put down, each containing -20 hams. The hams weighed from 14 to 16 pounds and had received -the usual 48-hour chilling. The pickling solutions employed were -the regular curing pickles of the establishment at which the experiment -was carried out. The curing pickle in one tierce was inoculated -with 400 cubic centimeters of a culture suspension of the bacillus, -prepared in the same manner as that used for the injection of the -hams in tierce 2 in Experiment II. A microscopic preparation made -from a small drop of the culture suspension before adding it to the -pickle showed the bacilli in large numbers, and in the 400 cubic -centimeters of the suspension there were millions of the bacteria. -The curing pickle in the other tierce was left untreated, the hams -in this tierce serving as a check. The tierces used in this experiment, -as in all of the experiments, were thoroughly cleaned with boiling -water before the hams were placed in them. The experiment was -conducted in a pickling room which was held at 33° to 36° F., and -the tierces were rolled three times during the cure. The details of -the experiment are as follows:</p> - -<div class="blockquot"> - -<p><i>Tierce 1.</i>—Contained 20 hams, half of which were pumped in both body and shank -and half in the shank only. As soon as they were pumped the hams were packed in -the tierce. Sufficient curing pickle to fill the tierce was then measured out in a clean -barrel and to it was added the culture suspension. The culture was thoroughly mixed -with the pickle and the latter was then run into the tierce containing the hams.</p> - -<p>Result: When tested at the end of the cure, two of the hams which had been -pumped in the shank only showed slight souring in the body. The rest of the hams -were sweet.</p> - -<p><i>Tierce 2.</i>—Contained 20 hams which were pumped in the same manner as those in -tierce 1. The curing pickle was the same as that used for tierce 1, but without the<span class="pagenum" id="Page_35">[Pg 35]</span> -addition of culture. This tierce was put down as a check on tierce 1, the hams being -cured under exactly the same conditions, but without the addition of culture to the -curing pickle.</p> - -<p>Result: One of the hams which was pumped in the shank only developed slight -souring in the body. The remainder of the hams were sweet.</p> -</div> - -<p>Comparing tierce 1, which contained the inoculated pickle, with -tierce 2, the check tierce which contained uninoculated pickle, we -find there was practically no difference in the final result. In tierce -1 two of the hams developed slight souring, while in tierce 2 one of -the hams became slightly sour. All of these hams had been pumped -in the shank only. The fact that one of the hams in the check tierce -developed slight souring was undoubtedly due to bacterial contamination -in pumping or in the handling which the hams underwent prior -to pickling, and the slight souring of the two hams in tierce 1 must -also be attributed to the same cause or causes, for had the souring -in these last hams resulted from the penetration of the bacteria from -the pickling solution a higher percentage should have become sour. -Furthermore, if the souring of the two hams in tierce 1 had resulted -from the penetration of the bacteria from the curing pickle, the souring -should have been general throughout the bodies of these hams, -whereas the souring was only evident around the bone and was slight -in degree.</p> - -<p>From this experiment the conclusion would seem justified that the -bacillus which causes ham souring does not usually find its way into -the bodies of the hams from the curing pickle, although it would be -going too far, perhaps, to say that infection never takes place from -the curing pickle. The experiment, however, indicates clearly that -the curing pickles are certainly not the main channel through which -the hams become infected. In referring to the curing pickles, it -should be understood that we refer here to the pickling solutions in -which the hams are immersed, and not to the pumping pickles. The -possibility of infection through the pumping pickle will be discussed -later.</p> - - -<h4><span class="smcap">Possible Infection through Manipulation or Handling.</span></h4> - -<p>There are at least three possible ways in which hams may become -infected from the handling which they receive in preparation for, or -during the process of curing, viz: From the thermometers used in -taking the inside temperatures of the hams, from the pumping -needles, and from the billhooks used in lifting the hams.</p> - - -<h5>INFECTION FROM HAM THERMOMETERS.</h5> - -<div class="figleft illowp20" id="fig4" style="max-width: 9.375em;"> -<img class="w100" src="images/fig4.jpg" alt=""/> -<div class="caption"><p class="hang"><span class="smcap">Fig. 4.</span>—Diagrammatic views showing -construction of ham thermometer. A, front view, showing open space -between metal point and mercury bulb, which becomes filled with -particles of meat, grease, and dirt; B, side view.</p></div> -</div> - -<p>The packing-house method of taking the temperatures of hams by -means of a pointed, metal-capped thermometer which is thrust deep -into the bodies of the hams has already been referred to, but deserves -to be described somewhat more in detail, as it will be at once apparent<span class="pagenum" id="Page_36">[Pg 36]</span> -that this manipulation furnishes a ready means -whereby hams may become infected with putrefactive -bacteria. The construction of a ham thermometer -is shown in figure 4.</p> - -<p>The instrument consists of a glass thermometer -inclosed in a metal case, the front portions of the -case being cut away so as to expose the scale above -and the mercury bulb below. As was explained -before, the thermometer is thrust deep into the -body of the ham so that the pointed end containing -the mercury bulb rests beside or a little behind -the upper portion of the femur, the bone being -used as a guide in introducing the thermometer.</p> - -<p>Ham temperatures are taken at three stages in -the preparation for cure—(1) on the hanging floor, -just before the hams go to the chill rooms, in order -to determine the amount of heat lost prior to chilling; -(2) on leaving the chill rooms, in order to determine -the thoroughness of the chill;(3) on the -packing floor, just before the hams are placed in -pickle, as a further check on the thoroughness of -the chilling.</p> - -<p>In taking the temperatures of hams which have -been chilled—and most of the temperatures are -taken subsequent to chilling—it is customary for -the packing-house attendant who has this matter -in charge to warm the thermometer by holding the -pointed or bulb end in his hand, so as to force the -mercury column up to about 60° F., or well above -the temperature of hams. The thermometer is -then thrust into the ham and allowed to remain -for several minutes, by which time the mercury -column will have fallen to the temperature of the -ham. The thermometer is then slowly withdrawn -so as to expose the top of the mercury column, and -an accurate reading is thus obtained of the inside -temperature of the ham. The thermometer is -warmed by the hand before each ham is tested, and -this undoubtedly insures more accurate readings -than would result were the thermometer removed -from one ham and plunged immediately into -another, but the procedure is open to certain -objections, for the open space between the -metal point of the thermometer and the mercury<span class="pagenum" id="Page_37">[Pg 37]</span> -bulb soon becomes filled with particles of meat and with grease and -dirt from the attendant’s hands, and it is at once apparent that a -thermometer in this condition would furnish a ready means whereby -extraneous matter might be introduced into the bodies of the hams. -In other words, a contaminated thermometer would furnish an excellent -means whereby hams could be inoculated with putrefactive -bacteria.</p> - -<p>In order to determine whether hams actually become inoculated in -this manner, the following experiment was carried out:</p> - - -<h5>EXPERIMENT TO SHOW WHETHER HAMS BECOME INFECTED FROM HAM THERMOMETERS.</h5> - -<p>This experiment was designed to show (1) whether the usual -packing-house method of taking ham temperatures was apt to induce -souring in the hams thus tested, and (2) whether souring would result -in hams which were tested with a thermometer purposely contaminated -with the bacillus isolated from sour hams.</p> - -<p>The experiment was carried out as follows: Thirty hog carcasses -were selected as they entered the hanging floor from the killing floor. -They had been cleaned, eviscerated, and split, and were of the same -average weight and of sufficient size to yield hams weighing from 12 -to 14 pounds. They were divided into three lots of 10 each and were -allowed to remain on the hanging floor for two hours, after which they -were given the usual 48-hour chilling.</p> - -<div class="blockquot"> - -<p><i>Lot 1.</i>—The hams in this lot were tested with an ordinary ham thermometer as they -entered the hanging floor, as they left the hanging floor, and as they left the coolers. -The thermometer used was borrowed from one of the plant attendants and was used in -the condition in which it was received from him; that is, it was not cleaned or disinfected -prior to use.</p> - -<p><i>Lot 2.</i>—The hams in this lot were tested as they entered the hanging floor with a -thermometer which had been previously cleaned and disinfected and then dipped in -a culture suspension of the meat-souring bacillus which was isolated from sour hams. -The thermometer was dipped in the culture suspension before each ham was tested. -No further temperatures were taken of these hams. The thermometer was carefully -cleaned and disinfected before it was returned to the attendant from whom it was -borrowed.</p> - -<p><i>Lot 3.</i>—The hams in this lot were not tested at all, and were intended as checks on -the cure.</p> -</div> - -<p>The three lots of carcasses were carefully tagged and were chilled in -a special cooler to themselves. Upon leaving the cooler the hams -were cut from the carcasses and trimmed. The three lots of hams -were then cured in separate tierces. All of the hams were subjected to -exactly the same cure.</p> - -<p>The pickles used were the regular pumping and regular curing -pickles of the establishment at which the experiment was carried out.</p> - -<p><span class="pagenum" id="Page_38">[Pg 38]</span></p> - -<p>The hams in lot 3 were pumped first and those in lot 1 were -pumped next. The needle was then removed and a fresh, clean -needle was used for lot 2. This was done in order to prevent the -possibility of carrying over bacteria from one lot of hams to another -on the pumping needle. The tierces were thoroughly cleaned with -boiling water before being used. The curing was carried out in a -pickling cellar which was held at 33° to 36° F., the temperature never -rising above the latter figure. The tierces were rolled three times -during the curing. The details and results were as follows:</p> - -<div class="blockquot"> - -<p><i>Tierce 1.</i>—Contained 20 hams, half of which were pumped in both body and shank -and half in the shank only. These hams were taken from the carcasses in lot 1 and had -been tested several times with a ham thermometer, as already described.</p> - -<p>Result: At the end of the cure it was found that of the 10 hams which were pumped -in the shank, 5 showed well-marked souring in the body, while of the 10 hams which -were pumped in both body and shank, 2 showed slight souring in the body.</p> - -<p><i>Tierce 2.</i>—Contained 20 hams, which were pumped in the same manner as those in -tierce 1. These hams were taken from the carcasses in lot 2 and had been tested once -with a thermometer which was dipped in a culture suspension of the bacillus isolated -from sour hams.</p> - -<p>Result: The 10 hams which were pumped in the shank only all became sour. When -they were tried out at the end of the cure, they showed pronounced souring throughout -the entire body and were classed as “stinkers” by the meat inspector who examined -them. The souring extended through to the bone marrow of the femur in all of these -hams. Of the 10 hams which were pumped in both body and shank, 7 showed -well-marked souring in the body, but not as pronounced as in those pumped in the -shank only; in five of these hams the souring extended through to the bone marrow of -the femur, while in 2 the bone marrow remained sweet.</p> - -<p><i>Tierce 3.</i>—Contained 20 hams, which were pumped in the same manner as those in -the two preceding tierces. These hams were not tested with a thermometer, and were -put down as a check on the cure. They were pumped with the same pumping pickle, -subjected to the same cure, and held under precisely the same conditions as the hams -in the two preceding tierces.</p> - -<p>Result: When tested at the end of the cure, all of these hams were found to be -perfectly sound and sweet.</p> -</div> - - -<p class="center"><i>Results of experiment to show whether hams become infected from ham thermometers.</i></p> - -<table class="standard" summary=""> -<tr> -<th class="tdc brdr" rowspan="2">No. of tierce.</th> -<th class="tdc brdr" rowspan="2">Number of hams.</th> -<th class="tdc brdr" rowspan="2">Average weight of hams.<br /><i>Pounds.</i></th> -<th class="tdc brdr" rowspan="2">How pumped.</th> -<th class="tdc brdr" rowspan="2">Treatment.</th> -<th class="tdc brdr" colspan="2">Condition at end of cure.</th> -</tr> -<tr> -<th class="tdc brdr">Number of sour hams.</th> -<th class="tdc brdr">Percentage of sour hams.</th> -</tr> -<tr> -<td class="tdr_br" rowspan="2">1</td> -<td class="tdr_br" rowspan="2">20</td> -<td class="tdr_br" rowspan="2">12-14</td> -<td class="tdl_br">10 in shank</td> -<td class="tdl_br">Tested in several stages in preparation for cure -which had not been cleaned.</td> -<td class="tdr_br">5</td> -<td class="tdr_br">50</td> -</tr> -<tr> -<td class="tdl_br">10 in body and shank</td> -<td class="tdc_br">do</td> -<td class="tdr_br">2</td> -<td class="tdr_br">20</td> -</tr> -<tr> -<td class="tdr_br" rowspan="2">2</td> -<td class="tdr_br" rowspan="2">20</td> -<td class="tdr_br" rowspan="2">14-16</td> -<td class="tdl_br">10 in shank</td> -<td class="tdl_br">Tested once with ham thermometer dipped -in culture suspension of anaerobic bacillus isolated -from sour hams.</td> -<td class="tdr_br">10</td> -<td class="tdr_br">100</td> -</tr> -<tr> -<td class="tdl_br">10 in body and shank</td> -<td class="tdc_br">do</td> -<td class="tdr_br">7</td> -<td class="tdr_br">70</td> -</tr> -<tr> -<td class="tdr_brb" rowspan="2">3</td> -<td class="tdr_brb" rowspan="2">20</td> -<td class="tdr_brb" rowspan="2">14-16</td> -<td class="tdl_br">10 in shank</td> -<td class="tdl_br">Not tested with thermometer.</td> -<td class="tdr_br">0</td> -<td class="tdr_br">0</td> -</tr> -<tr> -<td class="tdl_brb">10 in body and shank</td> -<td class="tdc_brb">do</td> -<td class="tdr_brb">0</td> -<td class="tdr_brb">0</td> -</tr> -</table> - - -<p><span class="pagenum" id="Page_39">[Pg 39]</span></p> - -<p>Several hams from each tierce were examined bacteriologically. -cultures being taken from the meat near the bone and from the bone -marrow of the femur.</p> - -<p>In the sour hams from tierce 1 cultures taken from the meat near -the bone showed the same anaerobic bacillus noted in other sour -hams (i. e., the same bacillus which caused souring in Experiments I -and II), but these cultures were contaminated with other bacteria -which were probably introduced on the thermometer along with the -ham-souring bacillus. None of the contaminating bacteria were -capable, however, of producing a sour-meat odor when grown on the -egg-pork medium. Pure cultures of the ham-souring bacillus were -obtained from the bone marrow of some of these hams, showing that -this bacillus had penetrated through to the bone marrow while the -other bacteria had not.</p> - -<p>From the sour hams in tierce 2 the ham-souring bacillus was -recovered readily, and often in pure culture, from the hams which -had been pumped in the shank only, whereas it was usually contaminated -with pickle bacteria in the hams which had been pumped -in both body and shank.</p> - -<p>In the case of the sound hams in tierce 3, cultures taken from the -meat near the bone and from the bone marrow of the femur were -negative in the hams which had been pumped in the shank only, -while cultures taken from corresponding points in the hams pumped -in both body and shank showed ordinary pickle bacteria, which had -evidently been introduced into the bodies of these hams in the pumping -pickles. None of these hams exhibited the slightest sour odor.</p> - -<p><i>Summary of experiment.</i>—In this experiment 20 hams (tierce 1) -were tested with an ordinary ham thermometer in the usual packing-house -manner. Half of these hams were subjected to the mild cure -and half were given the regular cure, with the result that 50 per cent -of those receiving the mild cure and 20 per cent of those receiving the -regular cure became sour.</p> - -<p>A second lot of 20 hams (tierce 2) were tested with a thermometer -which had been purposely contaminated with a culture suspension of -the ham-souring bacillus. These hams were cured in the same manner -as the first lot, with the result that all of those receiving the mild -cure and 70 per cent of those receiving the regular cure became sour.</p> - -<p>A third lot of 20 hams (tierce 3) which had not been tested at all -were cured in the same manner as the two preceding lots, as a check -on the cure. All of these hams were sweet at the end of the cure.</p> - -<p>Inasmuch as the three lots of hams were cured under precisely the -same conditions and were handled in the same manner prior to pickling, -the only difference being that the hams in tierces 1 and 2 were -tested with the ham thermometer while those in tierce 3 were not, -we must conclude that the souring of the hams in tierces 1 and 2<span class="pagenum" id="Page_40">[Pg 40]</span> -resulted from the testing which these hams received. In the case -of tierce 1 the hams became infected from a thermometer which, in -the ordinary routine use of the packing house, had become accidentally -contaminated with the ham-souring bacillus. In the case -of tierce 2 the hams became infected from a thermometer which -had been artificially contaminated with the bacillus. The high -percentage of sours in this last lot is due to the fact that these -hams were heavily infected with the ham-souring bacillus, for owing -to the construction of the ham thermometer many thousands of the -bacilli were unquestionably introduced into each ham on the point -of the thermometer. In the ordinary routine of ham testing, where -hams become infected from foreign matter introduced on the thermometer, -the percentage of souring, as shown in tierce 1, would be -less, for it is not to be supposed that ham thermometers are always -contaminated with the ham-souring bacillus, but that they only -become so at times, and that probably only a few of the bacilli -are then introduced.</p> - -<p>This experiment, we think, proves conclusively (1) that the ham-souring -bacillus may be introduced into the bodies of hams on the -thermometers used in testing the hams, and (2) that the packing-house -method of taking ham temperatures by means of a thermometer -which is thrust deep into the bodies of the hams may cause souring -in the hams thus tested.</p> - -<p>As a further proof that hams may become contaminated in this -manner, a series of cultures were made from scrapings taken from -ham thermometers. The scrapings consisted of the accumulations -of bits of meat, grease, and dirt that collect on the thermometers, -and were taken from the thermometers while the latter were in -ordinary routine use in the packing house. In a series of six cultures -which were made from such scrapings at different times, the same -bacillus which was isolated from sour hams and shown to cause meat -souring was found three times. In other words, the ham-souring -bacillus was present in 50 per cent of the cultures made from thermometer -scrapings, and many hams undoubtedly become infected -from the thermometers. Souring would be almost certain to result -in mild-cure hams if these hams were tested with a thermometer -which had become accidentally contaminated with the ham-souring -bacillus, as the bacillus would have time to develop within the bodies -of the hams before being inhibited by the curing pickle, which penetrates -slowly into the bodies of these hams. In the case of regular -cure hams—that is, hams which are pumped in both body and shank—souring -would be much less apt to occur after the use of a contaminated -thermometer, as these hams are more or less saturated with a -strong pumping pickle at the beginning of the cure, which would -tend to inhibit the growth of any bacteria that might be introduced -on the thermometers.</p> - -<p><span class="pagenum" id="Page_41">[Pg 41]</span></p> - -<p>The fact that souring may result in hams from the use of a contaminated -thermometer would explain the occurrence of several sours in -one vat, for in testing hams just before they go into cure several hams -are usually tested in succession, and these would in all likelihood go -into the same vat. Supposing the thermometer to have been contaminated -with the ham-souring bacillus at the time these hams were -tested, this would explain a fact which has been often noted, namely, -the occurrence of several sours in one vat while other vats containing -the same run of hams show no sours.</p> - -<p>If souring resulted in all of the hams which are subjected to a thermometer -test in the daily routine of the packing house, this manipulation -alone might account for nearly all of the sours which occur, but -the experiment which has been just described shows that all of these -hams do not become sour. In tierce 1, where each ham was subjected -to three thermometer tests at different times, souring resulted in 35 -percent (this includes both mild and regular cure) of the hams thus -tested, and in actual practice the percentage of sours in hams which -have been subjected to the thermometer test would probably be -somewhat less. Quite a large percentage of sour hams are thus left -unaccounted for by the thermometer test, and we believe that these -are chiefly the result of contamination carried in on the pumping -needles or in the pumping pickles.</p> - - -<h5>INFECTION FROM PUMPING NEEDLES.</h5> - -<p>In view of the results obtained in the last experiment, in which it -was shown that hams may become infected from the use of ham thermometers, -it seemed not improbable that hams might also become -infected from the pumping needles, which, like the thermometers, -are thrust deep into the bodies of the hams beside the bone. In order -to throw some light upon this point, cultures were taken from the -grease and dirt that accumulate on the shields at the bases of the -pumping needles, as such material must undoubtedly be carried into -the hams at times on the needles. The ham-souring bacillus was -found several times in these cultures, and hence it is fair to infer that -hams may also become infected at times from the pumping needles, -just as they become infected from the thermometers. Bits of contaminated -meat and grease and particles of dirt carried in on the -pumping needles would be forced out into the hams by the pumping -pickle, which passes out through small openings or fenestræ in the -needles, and this probably affords one explanation as to why so many -more body sours occur in the mild-cure hams. In the mild-cure hams, -which are pumped in the shank only, the pumping needle is introduced -near the femorotibial articulation, and the shank is saturated -at the start with a strong brine solution, while the body of the ham is -not. If the ham-souring bacillus were carried into these hams on<span class="pagenum" id="Page_42">[Pg 42]</span> -the pumping needle, the growth of the bacillus in the shank would be -inhibited by the strong brine solution with which the shank is saturated, -but there would be nothing to prevent the bacillus from growing -upward into the body of the ham, which has not been pumped and is -free from pickle. This would also explain the fact that the souring -often starts at the knee joint and extends upward into the body of -the ham. In the case of the regular cure hams, where the ham is -pumped in both body and shank, the entire ham is more or less saturated -at the start with the strong brine of the pumping pickle, which -tends to inhibit the growth of the ham-souring bacillus even if this -bacillus should find its way into these hams on the pumping needles. -It is in the mild-cure or partly pumped hams, where the body of the -ham is left unpumped, that the ham-souring bacillus finds its best -opportunity for development, and the greater proportion of the sours -that occur in the packing house are found in these hams.</p> - -<p>As regards the possibility of infection from the pumping pickle -itself, it does not seem probable that this would often occur, for the -pumping and curing pickles are always prepared on an upper floor of -the pickling houses and are delivered to the pickle cellars in closed -pipes, so the chances for the accidental contamination of these solutions -from floating dust or dirt would not be great. Furthermore, -the strong brine of the pumping pickle would completely inhibit the -growth of the ham-souring bacillus, and the bacillus would be incapable -of multiplying, even if it found its way into the pickle. On the -other hand, laboratory experiments show that the bacillus or its -spores may remain alive for a considerable length of time in the pumping -pickle, so the possibility of infection from this source can not be -overlooked.</p> - - -<h5>INFECTION FROM BILLHOOKS.</h5> - -<p>After the hams are cut from the carcasses they are handled entirely -by means of billhooks. In handling the hams the hooks are inserted -beneath the skin of the shank at a point just above the tibio-femoral -articulation. The hooks should be inserted in the connective tissue -beneath the skin and should not penetrate the muscular tissue to -any depth. When the hams lie in the right position, with the butt -or large portion away from and the shank toward the operator, it is -an easy matter to pick them up in the proper manner; but when -they lie at different angles and are being rapidly handled it is almost -impossible to prevent the hook from penetrating the muscular tissues, -and if the hook should penetrate to the bone it might carry in foreign -matter contaminated with the meat-souring bacillus. It is not probable -that many hams become contaminated in this way, as the men -who handle the hams are very skillful in manipulating their hooks; -but the possibility that hams may become contaminated in this -manner should not be entirely overlooked.</p> - -<p><span class="pagenum" id="Page_43">[Pg 43]</span></p> - - -<h3>BIOLOGICAL AND MORPHOLOGICAL CHARACTERISTICS OF THE HAM-SOURING -BACILLUS.</h3> - - -<h4>CONDITIONS FAVORABLE TO GROWTH.</h4> - -<p>The most favorable medium for the growth of the organism was -found to be the modified egg-meat mixture of Rettger, which has -been previously described. In this medium the organism develops -rapidly at a temperature of 20° to 25° C., giving rise to the characteristic -sour-meat odor. Like the bacillus described by Klein, it also -grows readily on pork-agar and pork-bouillon containing glucose, -but differs from Klein’s bacillus in that it will grow, though less luxuriantly, -on ordinary nutrient media—agar, gelatin, and bouillon—without -the addition of glucose.</p> - -<p>The optimum temperature for growth is 20° to 25° C. The organism -does not grow at incubator temperature (37.5° C.). At ice-box -temperature (8° to 10° C.) it develops readily, although the growth -is less rapid than at 20° to 25° C. That the organism will develop at -even lower temperatures was shown in the inoculation experiments -with hams, where it developed and multiplied extensively in the -bodies of the hams at the temperature of the pickling cellars, which -are held usually at 34° to 36° F.(1° to 2° C.).</p> - -<p>The organism develops best in a neutral or slightly alkaline -medium.</p> - - -<h4>GROWTH ON DIFFERENT CULTURE MEDIA.</h4> - -<p><i>Growth on egg-pork medium.</i>—At a temperature of 20° to 25° C. -the cultures show a slight but distinct sour odor in from two to three -days. This odor, as before stated, closely resembles the odor of a -sour ham. Egg-pork cultures from three to five days old were given -to a trained meat inspector, who knew nothing whatever as to the -contents of the tubes, and he was asked to describe the odor; he -described it as that of a sour ham.</p> - -<p>At one week the albumins of the medium are gelatinized or partly -coagulated and the odor is more pronounced. At ten days the -albumins are completely coagulated except at the surface, where -there is no apparent growth; the odor is more putrefactive in nature, -and the reaction of the medium is slightly acid. At three weeks the -coagulated albumin splits up into fragments and appears to undergo -a slow digestion, gas bubbles form in the lower portion of the culture, -and the odor becomes distinctly putrefactive in character. The slow -digestion of the albumin is probably due to a proteolytic enzyme -elaborated by the bacillus.</p> - -<p>At the end of a week a dark zone usually appears at the surface of -the coagulated albumin and gradually darkens until it becomes -almost black. This zone is probably due to a pigment elaborated by -the bacillus.</p> - -<p><span class="pagenum" id="Page_44">[Pg 44]</span></p> - -<p>At ice-box temperature (8° to 10° C.) the same changes and the -same odor were noted, but were somewhat slower in developing.</p> - -<p><i>Glucose-pork-agar.</i>—This medium was prepared from pork in the -same manner as beef-agar, and contained 1 per cent of glucose. The -organism grows readily on this medium and may be conveniently -cultivated in deep stab cultures. The medium was always thoroughly -boiled and then rapidly cooled in order to expel the inclosed -air. The growth of the organism was found to vary considerably -with the reaction.</p> - -<p>When the reaction was +1.5, deep stab cultures at three days (20° -to 25° C.) showed a well-marked arborescent growth, appearing as -delicate filaments extending outward from the line of stab. The -growth stopped within one-fourth or one-half inch of the surface of -the agar on account of the presence of oxygen in the upper part of -the culture medium. As the growth extended toward the walls of -the test tube the agar became clouded, and there were sometimes gas -bubbles in the depth of the agar, but the gas formation was not -extensive.</p> - -<p>When the reaction of the agar is neutral or slightly alkaline, extensive -gas formation occurs and the agar is often much broken up.</p> - -<p>The cultures developed a disagreeable, somewhat putrefactive -odor, but did not give the characteristic sour-ham odor obtained from -the egg-pork cultures.</p> - -<p>The organism was also grown on anaerobic agar plates by Zinsser’s -method, which is said to give absolutely anaerobic conditions. The -colonies on agar have a cottony or woolly appearance at first, and -spread slowly, with slightly irregular margins.</p> - -<p>In glucose-pork-agar to which azolitmin was added the azolitmin -in the lower portion of deep stab cultures was completely decolorized -in five days at room temperature (20° to 25° C).</p> - -<p>In glucose-pork-agar containing neutral red the red color in the -lower portion of the tube was changed to yellow with the development -of fluorescence.</p> - -<p><i>Neutral gelatin.</i>—Tubes of ordinary neutral gelatin without the -addition of glucose were inoculated and held at ice-box temperature -(8° to 10° C). At five days a delicate white growth appeared along -the line of stab in the lower portion of the tube. At seven days the -growth showed fine radial striæ, presenting an arborescent or tree-like -appearance, and extended halfway from the line of stab to the -walls of the test tube. At two weeks the growth had caused a delicate -clouding of the medium in the lower portion of the tube. At -three weeks the gelatin in the lower portion of the tube had become -liquefied and the growth had settled to the bottom as a white precipitate.</p> - -<p><span class="pagenum" id="Page_45">[Pg 45]</span></p> - -<p>In gelatin containing glucose, gas bubbles are formed in the depth -of the medium through the splitting up of the glucose, and the -characteristic arborescent growth is obscured.</p> - -<p><i>Glucose-pork-bouillon.</i>—This medium was prepared from pork -instead of beef and contained 1 per cent of glucose. The best results -were obtained when the reaction of the medium was neutral or -slightly alkaline.</p> - -<p>Culture tubes, which had been previously boiled to expel the contained -air and then inoculated, were held in a Novy jar, in an atmosphere -of hydrogen at a temperature of 20° to 25° C. At three days -the tubes showed well-marked clouding. At one week the growth -appeared as a heavy, white, flocculent, cottony precipitate in the -bottom of the tubes with a slight flocculent precipitate above. -When the culture was removed from the jar and shaken, the heavy, -flocculent precipitate at the bottom of the tube broke up without -much difficulty, giving rise to a heavy uniform clouding with some -small floating masses, which soon settled to the bottom. On shaking -the tube some evolution of gas in the form of very fine bubbles was -noticed.</p> - -<p>In Smith fermentation tubes containing neutral glucose-pork-bouillon -the closed arm of the tube shows well-marked clouding with gas -formation at three days at room temperature (20° to 25° C). The -growth has a tufted, cottony appearance, and there are many filaments -and threads. The growth settles to the bottom of the closed -arm as a cottony, white precipitate (see Pl. IV). The organism -splits the glucose vigorously, and at 10 days the tubes show from -40 to 50 per cent of gas. The bouillon in the open arm of the tube -remains unclouded. The maximum gas production at room temperature -is reached in from 10 to 14 days, by which time the growth in the -closed arm has completely settled into the bend of the tube, leaving -the bouillon in the closed arm clear. The gas formula, as determined -by Smith’s method, was H/CO₂= 5/1. The reaction of the bouillon becomes -acid to phenolphthalein.</p> - -<p>The organism will grow on ordinary neutral bouillon without the -addition of glucose, and in Smith tubes containing this medium a -small amount of gas was formed, due to the splitting of the muscle -sugar.</p> - -<p>The bacillus also grows in a sugar-free broth—that is, a broth free -from muscle sugar—and from cultures grown in this medium a well-marked -indol test was obtained.</p> - -<p><i>Litmus-milk.</i>—The organism was grown in litmus-milk in Smith -fermentation tubes at 20° to 25° C. At seven days the litmus in the -lower portion of the closed arm had assumed a brownish-buff color. -At two weeks the litmus in the closed arm had been reduced to a<span class="pagenum" id="Page_46">[Pg 46]</span> -brownish-buff color except at the top of the tube, where a pale, -bluish tinge remained, and the litmus in the open arm showed very -slight reddening as compared with a check tube. At three weeks the -litmus in the closed arm was entirely reduced to a light, brownish-buff -color, and the litmus in the open arm showed a slight but distinct -reddening as compared with the check. The reddening of the -litmus in the open arm was evidently due to the transfusion of acids -formed by the growth of the bacillus in the closed arm. After several -weeks the milk -is slowly peptonized, -probably as a result -of enzyme action.</p> - - -<h4>MORPHOLOGY.</h4> - -<p>The organism is a large bacillus having an average size of 4 to 8 μ -in length by 0.5 to 0.7 μ in thickness, but there are many longer forms -measuring from 10 to 20 μ in length. It develops in long, irregular -chains or filaments, which at times show a slightly spiral form.</p> - -<div class="figcenter illowp50" id="fig5" style="max-width: 40em;"> -<a href="images/fig5lge.jpg"> -<img src="images/fig5.jpg" alt=""/></a> -<div class="caption"><p class="hang"><span class="smcap">Fig. 5.</span>—Ham-souring bacillus -(<i>Bacillus putrefaciens</i>) grown on egg-pork -medium, showing tendency to form chains. Partly developed and -fully developed spores are shown at ends of rods; also free spores. -(Pen-and-ink drawing made with camera lucida from preparation -stained by Gram’s method.× 640.)</p></div> -</div> - -<p>The individual organisms show at times a widely open, slightly -spiral form, which was more apparent in hanging-drop preparations made -from bouillon cultures, where the organisms had been comparatively -undisturbed. This appearance was also noted at times in the stained -sections of soured muscular tissue, where the organisms were stained in -place. The organism possesses no motility. It stains with the ordinary -aniline dyes and by Gram’s method.</p> - - -<h4>SPORE FORMATION.</h4> - -<p>The organism develops large, terminal spores, which are at first -oval, but when fully developed are perfectly round and measure -from 1.5 to 2 μ in diameter.</p> - -<p>Spores develop rapidly in the egg-pork medium at 20° to 25° C., -fully developed spores being noted in from five to seven days. At<span class="pagenum" id="Page_47">[Pg 47]</span> -ice-box temperature (8° to 10° C.) partly developed spores were -noted in the egg-pork medium at 10 days and fully developed -spores at 2 weeks.</p> - -<p>Occasional spores were noted in old agar and gelatin cultures, -but abundant spore formation was seen only in the egg-pork medium. -No spores were noted in bouillon cultures, even at 10 weeks.</p> - - -<h4>RESISTANCE TO HEAT AND CHEMICAL AGENTS.</h4> - -<p>In its vegetative form the bacillus is killed at 55° C. in 10 minutes. -The spores survive a temperature of 80° C. for 20 minutes, but are -killed at 100° C. in 10 minutes.</p> - -<p>When sodium chlorid and potassium nitrate were added to glucose-pork -broth in varying amounts, it was found that 3 per cent of -sodium chlorid or 3 per cent of potassium nitrate was sufficient to -inhibit completely the growth of the bacillus at room temperature -(20° to 25° C.).</p> - -<p>While the growth of the bacillus was inhibited by sodium chlorid -and potassium nitrate as just stated, it was found that very much -stronger solutions of the two salts failed to destroy the bacillus. -Thus it was found that the bacillus or its spores retained their vitality -after an exposure of 30 days in a solution containing 23 per cent of -sodium chlorid and 6 per cent of potassium nitrate.</p> - - -<h4>GAS PRODUCTION.</h4> - -<p>The organism splits glucose, but not lactose or saccharose. That -it possesses the power of splitting muscle sugar was shown by the -formation of gas in Smith fermentation tubes containing ordinary -neutral bouillon without the addition of any sugar.</p> - -<p>The formation of gas in glucose bouillon varies considerably with -the reaction of the medium. The largest amount of gas was formed -when the broth was neutral or slightly alkaline. When the reaction -of the broth was distinctly acid or distinctly alkaline the amount -of gas was diminished. The gas which is formed in bouillon cultures -consists chiefly of hydrogen and carbon dioxide. In order to collect -a sufficient amount of the gas for analysis, two large fermentation -tubes capable of holding 150 cubic centimeters each were constructed. -These tubes were filled with pork-bouillon and inoculated -with the bacillus. After 20 days at room temperature (20° to 25° C.) -the gas was collected and the carbon dioxide and hydrogen determined, -with the following result:</p> - -<table class="standard" summary=""> -<tr> -<td class="tdr"></td> -<td class="tdr">Cubic centimeters.</td> -</tr> -<tr> -<td class="tdl">Total amount of gas collected</td> -<td class="tdr">37.7</td> -</tr> -<tr> -<td class="tdl">Carbon dioxide, by absorption with NaOH</td> -<td class="tdr">6.2</td> -</tr> -<tr> -<td class="tdl">Hydrogen, by difference</td> -<td class="tdr">31.5</td> -</tr> -</table> - - -<p>This analysis gives an approximate gas formula of H/CO<sub>2</sub>= 5/1, which -agrees with the gas formula as determined in the small fermentation -tubes by Smith’s method.</p> - -<p><span class="pagenum" id="Page_48">[Pg 48]</span></p> - -<p>In hams which had undergone spontaneous souring and in hams -which had been artificially soured by inoculation, hydrogen-sulphid -was often noted when the sour portions of the meat were tested -with lead-acetate paper, but no distinct odor of the gas could be -obtained. Hydrogen sulphid was also noted in egg-pork cultures of -the bacillus.</p> - - -<h4>ACID PRODUCTION.</h4> - -<p>In glucose-bouillon, butyric and lactic acids are formed and the -reaction of the medium becomes distinctly acid. Butyric and lactic -acids were also noted in the egg-pork cultures.</p> - -<p>A series of Smith fermentation tubes containing 10 c. c. each of -glucose-pork broth medium was inoculated with the bacillus and -held at room temperature (20° to 25° C.). These cultures were -titrated against [N/40]NaOH, with phenolphthalein as an indicator at -intervals of two days up to nineteen days, and then at two-week -intervals up to sixty-one days. Three of the cultures were titrated -each time so as to give a fair average of the acidity of the cultures, -and an uninoculated check tube was also titrated each time to see -if there was any change in the reaction of the medium. The results -of the titrations are shown in the following table:</p> - - -<p class="center"><i>Acidity determinations in glucose-pork broth cultures.</i></p> - -<table class="standard" summary=""> -<tr> -<th class="tdc brdr">Age of culture<br />(days).</th> -<th class="tdc brdr">Culture<br />A.</th> -<th class="tdc brdr">Culture<br />B.</th> -<th class="tdc brdr">Culture<br />C.</th> -<th class="tdc brdr">Average.</th> -<th class="tdc brdr">Medium.</th> -<th class="tdc brdr">Acidity of<br />culture.</th> -</tr> -<tr> -<td class="tdr_br"></td> -<td class="tdr_br"></td> -<td class="tdr_br"></td> -<td class="tdr_br"></td> -<td class="tdr_br"></td> -<td class="tdr_br"></td> -<td class="tdr_br"><i>Per cent.</i></td> -</tr> -<tr> -<td class="tdc_br">2</td> -<td class="tdr_br">0.038</td> -<td class="tdr_br">0.030</td> -<td class="tdr_br">0.040</td> -<td class="tdr_br">0.036</td> -<td class="tdr_br">0.009</td> -<td class="tdr_br">0.027</td> -</tr> -<tr> -<td class="tdc_br">4</td> -<td class="tdr_br">.105</td> -<td class="tdr_br">.100</td> -<td class="tdr_br">.102</td> -<td class="tdr_br">.102</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.093</td> -</tr> -<tr> -<td class="tdc_br">6</td> -<td class="tdr_br">.106</td> -<td class="tdr_br">.110</td> -<td class="tdr_br">.109</td> -<td class="tdr_br">.108</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.099</td> -</tr> -<tr> -<td class="tdc_br">8</td> -<td class="tdr_br">.124</td> -<td class="tdr_br">.115</td> -<td class="tdr_br">.117</td> -<td class="tdr_br">.119</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.110</td> -</tr> -<tr> -<td class="tdc_br">10</td> -<td class="tdr_br">.128</td> -<td class="tdr_br">.130</td> -<td class="tdr_br">.126</td> -<td class="tdr_br">.128</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.119</td> -</tr> -<tr> -<td class="tdc_br">12</td> -<td class="tdr_br">.129</td> -<td class="tdr_br">.120</td> -<td class="tdr_br">.129</td> -<td class="tdr_br">.126</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.117</td> -</tr> -<tr> -<td class="tdc_br">19</td> -<td class="tdr_br">.126</td> -<td class="tdr_br">.125</td> -<td class="tdr_br">.125</td> -<td class="tdr_br">.125</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.116</td> -</tr> -<tr> -<td class="tdc_br">33</td> -<td class="tdr_br">.125</td> -<td class="tdr_br">.123</td> -<td class="tdr_br">.125</td> -<td class="tdr_br">.124</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.115</td> -</tr> -<tr> -<td class="tdc_br">47</td> -<td class="tdr_br">.122</td> -<td class="tdr_br">.120</td> -<td class="tdr_br">.121</td> -<td class="tdr_br">.121</td> -<td class="tdr_br">.009</td> -<td class="tdr_br">.112</td> -</tr> -<tr> -<td class="tdc_brb">61</td> -<td class="tdr_brb">.121</td> -<td class="tdr_brb">.116</td> -<td class="tdr_brb">.119</td> -<td class="tdr_brb">.118</td> -<td class="tdr_brb">.009</td> -<td class="tdr_brb">.109</td> -</tr> -</table> - - - -<p>From the above table it will be seen that the maximum acidity -was reached at ten days, after which there was a gradual reduction -in the acidity, due probably to the formation of ammonia compounds.</p> - - -<h4>PATHOGENIC PROPERTIES.</h4> - -<p>Rabbits, guinea pigs, and white mice were inoculated and fed with -cultures of the bacillus without effect, from which it would appear -that the bacillus possesses no pathogenic or disease-producing -properties.</p> - - -<h4>NATURE OF THE BACILLUS.</h4> - -<p>The bacillus is essentially a saprogenic bacterium with zymogenic -properties. A preliminary study of the chemical changes which take -place in sour hams shows that these changes are of a putrefactive -nature. Hams which had undergone spontaneous souring were compared -with hams which had been artificially soured by inoculation, -and the chemical changes were found to be identical. A chemical -study was also made of the changes taking place in egg-pork cultures -of the bacillus at different stages of growth, and these changes were -found to be of a putrefactive nature and similar in character to the -changes which occur in sour hams. Among the putrefactive products -formed by the growth of the bacillus in the egg-pork medium were -indol, skatol, volatile fatty acids, skatol-carbonic acid, and hydrogen -sulphid.<a id="FNanchor_4" href="#Footnote_4" class="fnanchor">[4]</a></p> - -<div class="footnote"> - -<p><a id="Footnote_4" href="#FNanchor_4" class="label">[4]</a> The tests for the putrefactive products formed by the growth of the bacillus in the egg-pork medium -were made by P. Castleman, of the Biochemic Division, who also determined the percentage composition -of the gas formed by the growth of the bacillus in the glucose-pork-bouillon medium.</p> -</div> - -<div class="caption"><span class="smcap center">Bul. 132, Bureau of Animal Industry, U. S. Dept. of Agriculture.</span> <span class="smcap"><a id="Plate_IV"></a>Plate IV.</span></div> - -<div class="figcenter illowp80" id="pl4" style="max-width: 50em;"> - <img class="w100" src="images/pl4.jpg" alt="" /> -<div class="caption"><p class="hang"><span class="smcap">Glucose Bouillon Culture in Smith Fermentation Tube at Four -Days. Culture Grown at Room Temperature (20° to 25° C.). -Growth Confined Entirely to Closed Arm, with Gas Collecting -at Top.</span></p></div> -</div> - -<p>A more extended study is now being carried on in the Biochemic -Division of the chemical changes which take place in hams during -the process of souring, together with a further study of the chemical -changes which result from the growth of the bacillus in the egg-pork -medium. The results of this investigation will be given in a later -paper.</p> - -<p>The bacillus described in this paper belongs to the class of putrefactive -anaerobes, which are widely distributed in nature in dust, soil, -and excrementitious matters. This group of bacteria contains both -pathogenic and nonpathogenic forms. The former have received -considerable attention, but the latter have never been thoroughly -cleared up. The bacillus isolated from sour hams belongs in the latter -category, being possessed of no pathogenic or disease-producing properties. -It occurs in the dust and dirt of the packing house and finds -its way into the hams in the various manipulations to which the hams -are subjected.</p> - -<p>The bacillus described in this paper does not seem to correspond -with any forms heretofore described. It differs from Klei bacillus -(<i>Bacillus fœdans</i>) in the following important particulars:(1) It forms -large terminal spores, whereas Klein’s bacillus formed no spores;(2) it -will grow at a temperature of 34° F., while Klei bacillus did not grow -below 50° F.;(3) it produces an acid reaction in culture media, while -Klei bacillus gave a distinctly alkaline reaction;(4) it will grow on -the ordinary nutrient media—gelatin, agar, and broth—without the -addition of glucose, while Klein’s bacillus did not;(5) it peptonizes -the casein in milk, whereas Klein’s bacillus had no action on milk; -(6) it liquefies gelatin more rapidly, causing complete liquefaction -after three weeks at 8° to 10° C., whereas Klein’s bacillus caused only -partial liquefaction after eight weeks at 20° C.;(7) it can be conveyed</p> -<p><span class="pagenum" id="Page_50">[Pg 50]</span></p> -<p>from turbid broth cultures to new culture material by means of the -platinum loop, whereas Klein’s bacillus could not be thus conveyed.</p> - -<p>For the bacillus described in the present paper the following name -is proposed:<i>Bacillus putrefaciens</i>.</p> - - -<h2>PREVENTION OF HAM SOURING.</h2> - -<p>As it has been shown that souring in hams results from the growth -of a bacterium which is introduced into the bodies of the hams in the -various manipulations which the hams undergo, the only way to eliminate -souring in hams, as they are cured in the larger packing establishments, -would be to cure the hams under aseptic or sterile conditions, -which would, of course, be a physical impossibility.</p> - -<p>While it will probably be impossible, therefore, to eliminate souring -entirely under the methods of ham curing which are at present employed -in the larger packing establishments, much can undoubtedly -be done toward reducing the percentage of sours. In the matter of -taking ham temperatures, for instance, if the thermometers used were -thoroughly cleaned and disinfected and the surfaces of the hams -seared at the point where the thermometer is introduced, infection -from this source could be entirely prevented; or it might be possible -so to regulate the temperature of the chill rooms that the taking of -ham temperatures could be discontinued.</p> - -<p>The elimination of the souring that results from the introduction -of foreign matter on the pumping needles could be effected in two -ways only,(1) by not pumping the hams at all, or (2) by pumping -them under sterile or aseptic conditions. As has been stated before, -some of the smaller packing establishments cure their hams without -pumping, and in these establishments the percentage of sours runs -very low. When hams are cured without pumping, however, the -period of curing has to be materially lengthened in order to give the -curing pickles sufficient time to penetrate thoroughly, and this is -what the larger plants wish to avoid because of the greater space and -greater number of vats which would be necessitated. The object of -pumping in the larger plants, where the number of hams handled -daily runs into the thousands, is to hasten the cure and thus prevent -the accumulation of a great number of hams at one time. It is -doubtful, therefore, whether the larger packing houses could conveniently -discontinue pumping.</p> - -<p>To pump the hams under aseptic conditions would necessitate a -technique far too elaborate for routine use in the packing house; in -fact, anything like complete asepsis would be out of the question. -Certain measures might be adopted, however, that would tend to -prevent the possible introduction of ham-souring bacilli in the process -of pumping. It would undoubtedly be safer, for instance, to -boil the pumping pickle before use, and the chances of carrying in<span class="pagenum" id="Page_51">[Pg 51]</span> -contaminated foreign matter on the pumping needles could be lessened -by sterilizing the pumps and needles with boiling water and by frequently -dipping the needles, while in use, in boiling water. If the -hams were sprayed with clean water just prior to pumping, there -would be less likelihood of carrying in foreign matter on the needles. -The danger of introducing contaminated foreign matter on the needles -might be further obviated by searing the surfaces of the hams at -the points where the needles are introduced; but such a procedure -would be hardly practicable in the larger packing houses, where the -great number of hams cured necessitates rapid handling.</p> - -<p>While the danger of possible contamination in pumping, through -the introduction of contaminated foreign matter on the pumping -needles, can not well be avoided, this danger is partly counterbalanced -by the inhibitory action of the pumping pickle, which is strikingly -shown in the experiments which have been described. In these -experiments, 100 hams received large doses of the ham-souring bacillus, -half of these hams being subjected to the mild cure and half to the -regular cure, with the following result: In the case of the mild-cure -hams, which were pumped in the shank only, the percentage -of sours was practically 100 per cent, every ham with possibly one -exception becoming sour; whereas in the regular-cure hams, which -were pumped in both body and shank, only 58 per cent of the hams -became sour. In other words, the additional pumping which the -regular-cure hams received served to prevent souring in 42 per cent -of these hams. In these experiments the number of bacteria introduced -into the hams was very great, thousands and even millions of -the bacilli being introduced into each ham, whereas in the routine of -the packing house it is not likely that more than a few of the bacilli -are ever introduced at one time on the thermometers and pumping -needles. In view of these results it is safe to say that in the larger -packing houses, where pumping seems to be necessary, the number -of sours could be reduced fully 50 per cent if all hams were pumped in -the body as well as in the shank.</p> - -<p>At present the usual procedure is to pump all hams, both mild and -regular cure, with the same pumping pickle, the mild-cure hams -being pumped in the shank only and the regular-cure hams at two -additional points in the body. The experiments quoted above -show that the additional pumping which the regular-cure hams -receive undoubtedly tends to prevent the development of souring -in these hams, and this result is unquestionably due to the inhibitory -action of the salts contained in the pumping pickle, as it was found -by laboratory experiment that the addition of 3 per cent of sodium -chlorid to culture media is sufficient to inhibit the growth of the -ham-souring bacillus. The pumping pickles consist of strong brine -solutions and always contain considerably more than 3 per cent of<span class="pagenum" id="Page_52">[Pg 52]</span> -sodium chlorid. If, therefore, the pumping of regular-cure hams -were made more thorough than at present, and all of the deeper portions -of the ham were thoroughly saturated with the strong brine -solution, souring could be largely eliminated, if not entirely prevented, -in these hams, as an unfavorable medium or soil would thus be -created in which the ham-souring bacillus could not develop. The -ham-souring bacillus is able to develop within the bodies of the -regular-cure hams because the pumping of these hams is not always -thorough and there are certain areas in the inner or deeper portions -of the hams in which the tissues are not thoroughly saturated with -the pumping pickle.</p> - -<p>Under the present methods of curing, the greater proportion of -the sours occur among the partly pumped or mild-cure hams. These -hams are pumped in the shank only, and the growth of the ham-souring -bacillus within the bodies of these hams is not interfered -with until the curing pickle has penetrated from the outside. As -it requires several weeks for the curing pickle to penetrate thoroughly -into the deeper portions of these hams, the bacillus is thus -afforded a considerable interval in which to develop before it is -exposed to the inhibitory action of the pickle. If these hams -could be thoroughly pumped in the body at the beginning of the cure -in the same manner as the regular-cure hams, the chief loss from -ham souring would be eliminated. It would not do, however, to -pump these hams in the body with the same pumping pickle used in -the regular cure, as the meat would be rendered too salty and the -mild flavor of the ham would be lost. There is undoubtedly a demand -for mild-cure hams, otherwise they would not be on the market; and -the question then arises how to pump these hams and still retain a -mild cure. This might be accomplished by pumping these hams -with their own curing pickle, which is usually a milder pickle than -that employed in the regular cure, or an even milder pumping pickle -might be used. If mild-cure hams were pumped in this way, the -percentage of souring in these hams could undoubtedly be greatly -diminished without materially affecting the flavor of the ham.</p> - -<p>To recapitulate briefly, the prevention of ham souring is to be -sought in two ways:(1) Through greater care in handling the -hams and the adoption of precautionary measures to prevent the introduction -of the ham-souring bacillus into the bodies of the hams, -and (2) through more thorough pumping of the deeper or inner portions -of the hams, so as to create an unfavorable soil or medium in -which the ham-souring bacillus can not develop even if it should -gain entrance into the bodies of the hams.</p> - -<p>From what has been said it will be apparent that ham souring -can probably never be entirely eliminated from the packing house -under the present methods of curing, but the adoption of precaution<span class="pagenum" id="Page_53">[Pg 53]</span>ary -measures in testing and pumping hams, together with a more -thorough pumping of all hams in ways similar to those suggested, -would unquestionably reduce very materially the losses from this -source.</p> - - -<h2>GENERAL SUMMARY AND CONCLUSIONS.</h2> - -<p>1. In this paper it has been shown that ham souring, as encountered -in the wet cure where the hams are entirely submerged in pickling -fluids, is due to the growth of an anaerobic bacillus within the bodies of -the hams. This bacillus (<i>B. putrefaciens</i>) was found in sour hams -obtained from four different packing establishments. It was isolated -and grown in various laboratory media, in one of which, the egg-pork -medium, it gave rise to the characteristic sour-ham odor. -This bacillus was the only organism that could be isolated from sour -hams that was capable of producing the characteristic sour-ham odor -in the egg-pork medium.</p> - -<p>2. When injected into the bodies of sound hams, the bacillus -caused these hams to sour in the process of curing. In hams which -had been inoculated with the bacillus and thus artificially soured, the -bacillus was recovered in cultures taken at points far removed, -relatively speaking, from the point of inoculation, indicating that -the bacillus had multiplied and progressed by extension throughout -the bodies of the hams.</p> - -<p>3. The bacillus possesses no motility, and its extension throughout -the bodies of the hams is a result of multiplication. In its growth -it follows along the connective-tissue bands between the muscle -bundles, which are composed of comparatively loose tissue and -afford paths of least resistance. When it invades the muscle tissue -proper, it follows along the sarcolemma sheaths between the muscle -fibers. As a result of this growth the muscular tissue becomes softer -and tends to break more easily.</p> - -<p>4. The bacillus belongs to the class of putrefactive anaerobes -which are widely distributed in nature in dust, soil, and excrementitious -matters. The bacillus or its spores is present in the dust and -dirt of packing houses and finds its way into the hams in the various -manipulations to which they are subjected.</p> - -<p>5. The bacillus or its spores may be introduced into hams on the -thermometers used in testing the hams, on the pumping needles, -and possibly on the billhooks used in handling the hams. It may -also be carried into the hams in the pumping pickle, and may even -find its way into the hams from the curing pickle, although infection -through the latter channel probably does not often occur.</p> - -<p>6. The bacillus develops in the deeper portions of the ham because -of the anaerobic conditions there prevailing, and souring is most -often encountered, therefore, in the deeper portions of the ham -near the bone.</p> - -<p><span class="pagenum" id="Page_54">[Pg 54]</span></p> - -<p>7. A preliminary study of the chemical changes which take place -in the process of souring shows that these changes are of a putrefactive -nature, and ham souring, as ordinarily encountered, is to be -regarded as an incipient putrefaction. Hams which had been -artificially soured by injections of culture were compared with sour -hams obtained from the packing house, and the putrefactive changes -were found to be identical.</p> - -<p>8. Hams which have once become sour can never be restored to a -sound condition, because of the chemical changes which result from -the growth of the bacillus. In other words, the tissues of the ham -undergo certain chemical changes in the process of souring, and -when these changes have once taken place the tissues can never be -restored to a sound condition. The repumping of slightly soured -hams with a strong pumping pickle will check further souring, by -inhibiting the growth of the bacillus, but will not restore to a sound -condition those portions of the ham which have become sour.</p> - -<p>9. The salts of the pickling fluids have a marked inhibitory action -on the ham-souring bacillus, and sours occur less frequently in regular-cure -hams.</p> - -<p>10. In regular-cure hams the growth of the ham-souring bacillus -is restricted and often completely inhibited as a result of the additional -pumping which these hams receive, whereby they are more -or less saturated with pickle at the beginning of the cure.</p> - -<p>11. If the pumping of regular-cure hams were more thorough and -all of the deeper portions of the ham were thoroughly saturated -with the pumping pickle, souring could be largely eliminated if not -entirely prevented in the hams, as an unfavorable medium or soil -would thus be created, in which the ham-souring bacillus could not -develop. The reason that souring does develop in regular-cure hams -is because the pumping is not always thorough and there are certain -areas in the deeper portions of these hams which are not saturated -with the pumping pickle.</p> - -<p>12. Under the present methods of curing, the partly pumped or -mild-cure hams furnish the greater proportion of the sours, as these -hams are not pumped in the body and the growth of the ham-souring -bacillus within the bodies of these hams is not interfered -with until the curing pickle has penetrated from the outside. As -it requires several weeks for the curing pickle to penetrate thoroughly -into the deeper portions of these hams, the bacillus is thus afforded -a considerable interval in which to develop.</p> - -<p>13. The percentage of souring in the mild-cure hams could be -greatly reduced without materially affecting the cure by pumping -these hams with their own curing pickle, which is usually a milder -pickle than that employed in the regular cure; and if the pumping<span class="pagenum" id="Page_55">[Pg 55]</span> -were thorough the number of sours in these hams could be reduced -to a small figure.</p> - -<p>14. The only way by which ham souring could be entirely eliminated -from the larger packing establishments under the present methods -of curing would be to handle the hams throughout under aseptic -conditions, and this, for obvious reasons, would be an impossibility. -The losses from ham souring may be materially reduced, however, by -greater care in handling the hams and the adoption of precautionary -measures designed to prevent the introduction of contaminated -foreign matter into the bodies of the hams, together with more -thorough methods of pumping.</p> - - -<h2>ACKNOWLEDGMENTS.</h2> - -<p>In conclusion, the writer desires to express his obligations to Dr. -S. E. Bennett, of the Inspection Division, inspector in charge at -Chicago, for the assignment of trained meat inspectors to assist in -the work, as well as for kind assistance in obtaining data and material -for laboratory study, and to Dr. L. E. Day, of the Pathological -Division, who kindly prepared the sections which are figured and -described in the present article.</p> - -<div style='display:block; margin-top:4em'>*** END OF THE PROJECT GUTENBERG EBOOK A BACTERIOLOGICAL STUDY OF HAM SOURING ***</div> -<div style='text-align:left'> - -<div style='display:block; margin:1em 0'> -Updated editions will replace the previous one—the old editions will -be renamed. -</div> - -<div style='display:block; margin:1em 0'> -Creating the works from print editions not protected by U.S. copyright -law means that no one owns a United States copyright in these works, -so the Foundation (and you!) can copy and distribute it in the United -States without permission and without paying copyright -royalties. Special rules, set forth in the General Terms of Use part -of this license, apply to copying and distributing Project -Gutenberg™ electronic works to protect the PROJECT GUTENBERG™ -concept and trademark. Project Gutenberg is a registered trademark, -and may not be used if you charge for an eBook, except by following -the terms of the trademark license, including paying royalties for use -of the Project Gutenberg trademark. If you do not charge anything for -copies of this eBook, complying with the trademark license is very -easy. You may use this eBook for nearly any purpose such as creation -of derivative works, reports, performances and research. Project -Gutenberg eBooks may be modified and printed and given away—you may -do practically ANYTHING in the United States with eBooks not protected -by U.S. copyright law. Redistribution is subject to the trademark -license, especially commercial redistribution. -</div> - -<div style='margin-top:1em; font-size:1.1em; text-align:center'>START: FULL LICENSE</div> -<div style='text-align:center;font-size:0.9em'>THE FULL PROJECT GUTENBERG LICENSE</div> -<div style='text-align:center;font-size:0.9em'>PLEASE READ THIS BEFORE YOU DISTRIBUTE OR USE THIS WORK</div> - -<div style='display:block; margin:1em 0'> -To protect the Project Gutenberg™ mission of promoting the free -distribution of electronic works, by using or distributing this work -(or any other work associated in any way with the phrase “Project -Gutenberg”), you agree to comply with all the terms of the Full -Project Gutenberg™ License available with this file or online at -www.gutenberg.org/license. -</div> - -<div style='display:block; font-size:1.1em; margin:1em 0; font-weight:bold'> -Section 1. General Terms of Use and Redistributing Project Gutenberg™ electronic works -</div> - -<div style='display:block; margin:1em 0'> -1.A. By reading or using any part of this Project Gutenberg™ -electronic work, you indicate that you have read, understand, agree to -and accept all the terms of this license and intellectual property -(trademark/copyright) agreement. If you do not agree to abide by all -the terms of this agreement, you must cease using and return or -destroy all copies of Project Gutenberg™ electronic works in your -possession. If you paid a fee for obtaining a copy of or access to a -Project Gutenberg™ electronic work and you do not agree to be bound -by the terms of this agreement, you may obtain a refund from the person -or entity to whom you paid the fee as set forth in paragraph 1.E.8. -</div> - -<div style='display:block; margin:1em 0'> -1.B. “Project Gutenberg” is a registered trademark. It may only be -used on or associated in any way with an electronic work by people who -agree to be bound by the terms of this agreement. There are a few -things that you can do with most Project Gutenberg™ electronic works -even without complying with the full terms of this agreement. See -paragraph 1.C below. There are a lot of things you can do with Project -Gutenberg™ electronic works if you follow the terms of this -agreement and help preserve free future access to Project Gutenberg™ -electronic works. See paragraph 1.E below. -</div> - -<div style='display:block; margin:1em 0'> -1.C. The Project Gutenberg Literary Archive Foundation (“the -Foundation” or PGLAF), owns a compilation copyright in the collection -of Project Gutenberg™ electronic works. Nearly all the individual -works in the collection are in the public domain in the United -States. If an individual work is unprotected by copyright law in the -United States and you are located in the United States, we do not -claim a right to prevent you from copying, distributing, performing, -displaying or creating derivative works based on the work as long as -all references to Project Gutenberg are removed. Of course, we hope -that you will support the Project Gutenberg™ mission of promoting -free access to electronic works by freely sharing Project Gutenberg™ -works in compliance with the terms of this agreement for keeping the -Project Gutenberg™ name associated with the work. You can easily -comply with the terms of this agreement by keeping this work in the -same format with its attached full Project Gutenberg™ License when -you share it without charge with others. -</div> - -<div style='display:block; margin:1em 0'> -1.D. The copyright laws of the place where you are located also govern -what you can do with this work. Copyright laws in most countries are -in a constant state of change. If you are outside the United States, -check the laws of your country in addition to the terms of this -agreement before downloading, copying, displaying, performing, -distributing or creating derivative works based on this work or any -other Project Gutenberg™ work. The Foundation makes no -representations concerning the copyright status of any work in any -country other than the United States. -</div> - -<div style='display:block; margin:1em 0'> -1.E. Unless you have removed all references to Project Gutenberg: -</div> - -<div style='display:block; margin:1em 0'> -1.E.1. The following sentence, with active links to, or other -immediate access to, the full Project Gutenberg™ License must appear -prominently whenever any copy of a Project Gutenberg™ work (any work -on which the phrase “Project Gutenberg” appears, or with which the -phrase “Project Gutenberg” is associated) is accessed, displayed, -performed, viewed, copied or distributed: -</div> - -<blockquote> - <div style='display:block; margin:1em 0'> - This eBook is for the use of anyone anywhere in the United States and most - other parts of the world 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 <a href="https://www.gutenberg.org">www.gutenberg.org</a>. If you - are not located in the United States, you will have to check the laws - of the country where you are located before using this eBook. - </div> -</blockquote> - -<div style='display:block; margin:1em 0'> -1.E.2. If an individual Project Gutenberg™ electronic work is -derived from texts not protected by U.S. copyright law (does not -contain a notice indicating that it is posted with permission of the -copyright holder), the work can be copied and distributed to anyone in -the United States without paying any fees or charges. If you are -redistributing or providing access to a work with the phrase “Project -Gutenberg” associated with or appearing on the work, you must comply -either with the requirements of paragraphs 1.E.1 through 1.E.7 or -obtain permission for the use of the work and the Project Gutenberg™ -trademark as set forth in paragraphs 1.E.8 or 1.E.9. -</div> - -<div style='display:block; margin:1em 0'> -1.E.3. If an individual Project Gutenberg™ electronic work is posted -with the permission of the copyright holder, your use and distribution -must comply with both paragraphs 1.E.1 through 1.E.7 and any -additional terms imposed by the copyright holder. Additional terms -will be linked to the Project Gutenberg™ License for all works -posted with the permission of the copyright holder found at the -beginning of this work. -</div> - -<div style='display:block; margin:1em 0'> -1.E.4. Do not unlink or detach or remove the full Project Gutenberg™ -License terms from this work, or any files containing a part of this -work or any other work associated with Project Gutenberg™. -</div> - -<div style='display:block; margin:1em 0'> -1.E.5. Do not copy, display, perform, distribute or redistribute this -electronic work, or any part of this electronic work, without -prominently displaying the sentence set forth in paragraph 1.E.1 with -active links or immediate access to the full terms of the Project -Gutenberg™ License. -</div> - -<div style='display:block; margin:1em 0'> -1.E.6. You may convert to and distribute this work in any binary, -compressed, marked up, nonproprietary or proprietary form, including -any word processing or hypertext form. However, if you provide access -to or distribute copies of a Project Gutenberg™ work in a format -other than “Plain Vanilla ASCII” or other format used in the official -version posted on the official Project Gutenberg™ website -(www.gutenberg.org), you must, at no additional cost, fee or expense -to the user, provide a copy, a means of exporting a copy, or a means -of obtaining a copy upon request, of the work in its original “Plain -Vanilla ASCII” or other form. Any alternate format must include the -full Project Gutenberg™ License as specified in paragraph 1.E.1. -</div> - -<div style='display:block; margin:1em 0'> -1.E.7. Do not charge a fee for access to, viewing, displaying, -performing, copying or distributing any Project Gutenberg™ works -unless you comply with paragraph 1.E.8 or 1.E.9. -</div> - -<div style='display:block; margin:1em 0'> -1.E.8. You may charge a reasonable fee for copies of or providing -access to or distributing Project Gutenberg™ electronic works -provided that: -</div> - -<div style='margin-left:0.7em;'> - <div style='text-indent:-0.7em'> - • You pay a royalty fee of 20% of the gross profits you derive from - the use of Project Gutenberg™ works calculated using the method - you already use to calculate your applicable taxes. The fee is owed - to the owner of the Project Gutenberg™ trademark, but he has - agreed to donate royalties under this paragraph to the Project - Gutenberg Literary Archive Foundation. Royalty payments must be paid - within 60 days following each date on which you prepare (or are - legally required to prepare) your periodic tax returns. Royalty - payments should be clearly marked as such and sent to the Project - Gutenberg Literary Archive Foundation at the address specified in - Section 4, “Information about donations to the Project Gutenberg - Literary Archive Foundation.” - </div> - - <div style='text-indent:-0.7em'> - • You provide a full refund of any money paid by a user who notifies - you in writing (or by e-mail) within 30 days of receipt that s/he - does not agree to the terms of the full Project Gutenberg™ - License. You must require such a user to return or destroy all - copies of the works possessed in a physical medium and discontinue - all use of and all access to other copies of Project Gutenberg™ - works. - </div> - - <div style='text-indent:-0.7em'> - • You provide, in accordance with paragraph 1.F.3, a full refund of - any money paid for a work or a replacement copy, if a defect in the - electronic work is discovered and reported to you within 90 days of - receipt of the work. - </div> - - <div style='text-indent:-0.7em'> - • You comply with all other terms of this agreement for free - distribution of Project Gutenberg™ works. - </div> -</div> - -<div style='display:block; margin:1em 0'> -1.E.9. If you wish to charge a fee or distribute a Project -Gutenberg™ electronic work or group of works on different terms than -are set forth in this agreement, you must obtain permission in writing -from the Project Gutenberg Literary Archive Foundation, the manager of -the Project Gutenberg™ trademark. Contact the Foundation as set -forth in Section 3 below. -</div> - -<div style='display:block; margin:1em 0'> -1.F. -</div> - -<div style='display:block; margin:1em 0'> -1.F.1. Project Gutenberg volunteers and employees expend considerable -effort to identify, do copyright research on, transcribe and proofread -works not protected by U.S. copyright law in creating the Project -Gutenberg™ collection. Despite these efforts, Project Gutenberg™ -electronic works, and the medium on which they may be stored, may -contain “Defects,” such as, but not limited to, incomplete, inaccurate -or corrupt data, transcription errors, a copyright or other -intellectual property infringement, a defective or damaged disk or -other medium, a computer virus, or computer codes that damage or -cannot be read by your equipment. -</div> - -<div style='display:block; margin:1em 0'> -1.F.2. LIMITED WARRANTY, DISCLAIMER OF DAMAGES - Except for the “Right -of Replacement or Refund” described in paragraph 1.F.3, the Project -Gutenberg Literary Archive Foundation, the owner of the Project -Gutenberg™ trademark, and any other party distributing a Project -Gutenberg™ electronic work under this agreement, disclaim all -liability to you for damages, costs and expenses, including legal -fees. YOU AGREE THAT YOU HAVE NO REMEDIES FOR NEGLIGENCE, STRICT -LIABILITY, BREACH OF WARRANTY OR BREACH OF CONTRACT EXCEPT THOSE -PROVIDED IN PARAGRAPH 1.F.3. YOU AGREE THAT THE FOUNDATION, THE -TRADEMARK OWNER, AND ANY DISTRIBUTOR UNDER THIS AGREEMENT WILL NOT BE -LIABLE TO YOU FOR ACTUAL, DIRECT, INDIRECT, CONSEQUENTIAL, PUNITIVE OR -INCIDENTAL DAMAGES EVEN IF YOU GIVE NOTICE OF THE POSSIBILITY OF SUCH -DAMAGE. -</div> - -<div style='display:block; margin:1em 0'> -1.F.3. LIMITED RIGHT OF REPLACEMENT OR REFUND - If you discover a -defect in this electronic work within 90 days of receiving it, you can -receive a refund of the money (if any) you paid for it by sending a -written explanation to the person you received the work from. If you -received the work on a physical medium, you must return the medium -with your written explanation. The person or entity that provided you -with the defective work may elect to provide a replacement copy in -lieu of a refund. If you received the work electronically, the person -or entity providing it to you may choose to give you a second -opportunity to receive the work electronically in lieu of a refund. If -the second copy is also defective, you may demand a refund in writing -without further opportunities to fix the problem. -</div> - -<div style='display:block; margin:1em 0'> -1.F.4. Except for the limited right of replacement or refund set forth -in paragraph 1.F.3, this work is provided to you ‘AS-IS’, WITH NO -OTHER WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT -LIMITED TO WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PURPOSE. -</div> - -<div style='display:block; margin:1em 0'> -1.F.5. Some states do not allow disclaimers of certain implied -warranties or the exclusion or limitation of certain types of -damages. If any disclaimer or limitation set forth in this agreement -violates the law of the state applicable to this agreement, the -agreement shall be interpreted to make the maximum disclaimer or -limitation permitted by the applicable state law. The invalidity or -unenforceability of any provision of this agreement shall not void the -remaining provisions. -</div> - -<div style='display:block; margin:1em 0'> -1.F.6. INDEMNITY - You agree to indemnify and hold the Foundation, the -trademark owner, any agent or employee of the Foundation, anyone -providing copies of Project Gutenberg™ electronic works in -accordance with this agreement, and any volunteers associated with the -production, promotion and distribution of Project Gutenberg™ -electronic works, harmless from all liability, costs and expenses, -including legal fees, that arise directly or indirectly from any of -the following which you do or cause to occur: (a) distribution of this -or any Project Gutenberg™ work, (b) alteration, modification, or -additions or deletions to any Project Gutenberg™ work, and (c) any -Defect you cause. -</div> - -<div style='display:block; font-size:1.1em; margin:1em 0; font-weight:bold'> -Section 2. Information about the Mission of Project Gutenberg™ -</div> - -<div style='display:block; margin:1em 0'> -Project Gutenberg™ is synonymous with the free distribution of -electronic works in formats readable by the widest variety of -computers including obsolete, old, middle-aged and new computers. It -exists because of the efforts of hundreds of volunteers and donations -from people in all walks of life. -</div> - -<div style='display:block; margin:1em 0'> -Volunteers and financial support to provide volunteers with the -assistance they need are critical to reaching Project Gutenberg™’s -goals and ensuring that the Project Gutenberg™ collection will -remain freely available for generations to come. In 2001, the Project -Gutenberg Literary Archive Foundation was created to provide a secure -and permanent future for Project Gutenberg™ and future -generations. To learn more about the Project Gutenberg Literary -Archive Foundation and how your efforts and donations can help, see -Sections 3 and 4 and the Foundation information page at www.gutenberg.org. -</div> - -<div style='display:block; font-size:1.1em; margin:1em 0; font-weight:bold'> -Section 3. Information about the Project Gutenberg Literary Archive Foundation -</div> - -<div style='display:block; margin:1em 0'> -The Project Gutenberg Literary Archive Foundation is a non-profit -501(c)(3) educational corporation organized under the laws of the -state of Mississippi and granted tax exempt status by the Internal -Revenue Service. The Foundation’s EIN or federal tax identification -number is 64-6221541. Contributions to the Project Gutenberg Literary -Archive Foundation are tax deductible to the full extent permitted by -U.S. federal laws and your state’s laws. -</div> - -<div style='display:block; margin:1em 0'> -The Foundation’s business office is located at 809 North 1500 West, -Salt Lake City, UT 84116, (801) 596-1887. Email contact links and up -to date contact information can be found at the Foundation’s website -and official page at www.gutenberg.org/contact -</div> - -<div style='display:block; font-size:1.1em; margin:1em 0; font-weight:bold'> -Section 4. Information about Donations to the Project Gutenberg Literary Archive Foundation -</div> - -<div style='display:block; margin:1em 0'> -Project Gutenberg™ depends upon and cannot survive without widespread -public support and donations to carry out its mission of -increasing the number of public domain and licensed works that can be -freely distributed in machine-readable form accessible by the widest -array of equipment including outdated equipment. Many small donations -($1 to $5,000) are particularly important to maintaining tax exempt -status with the IRS. -</div> - -<div style='display:block; margin:1em 0'> -The Foundation is committed to complying with the laws regulating -charities and charitable donations in all 50 states of the United -States. Compliance requirements are not uniform and it takes a -considerable effort, much paperwork and many fees to meet and keep up -with these requirements. We do not solicit donations in locations -where we have not received written confirmation of compliance. To SEND -DONATIONS or determine the status of compliance for any particular state -visit <a href="https://www.gutenberg.org/donate/">www.gutenberg.org/donate</a>. -</div> - -<div style='display:block; margin:1em 0'> -While we cannot and do not solicit contributions from states where we -have not met the solicitation requirements, we know of no prohibition -against accepting unsolicited donations from donors in such states who -approach us with offers to donate. -</div> - -<div style='display:block; margin:1em 0'> -International donations are gratefully accepted, but we cannot make -any statements concerning tax treatment of donations received from -outside the United States. U.S. laws alone swamp our small staff. -</div> - -<div style='display:block; margin:1em 0'> -Please check the Project Gutenberg web pages for current donation -methods and addresses. Donations are accepted in a number of other -ways including checks, online payments and credit card donations. To -donate, please visit: www.gutenberg.org/donate -</div> - -<div style='display:block; font-size:1.1em; margin:1em 0; font-weight:bold'> -Section 5. General Information About Project Gutenberg™ electronic works -</div> - -<div style='display:block; margin:1em 0'> -Professor Michael S. Hart was the originator of the Project -Gutenberg™ concept of a library of electronic works that could be -freely shared with anyone. For forty years, he produced and -distributed Project Gutenberg™ eBooks with only a loose network of -volunteer support. -</div> - -<div style='display:block; margin:1em 0'> -Project Gutenberg™ eBooks are often created from several printed -editions, all of which are confirmed as not protected by copyright in -the U.S. unless a copyright notice is included. Thus, we do not -necessarily keep eBooks in compliance with any particular paper -edition. -</div> - -<div style='display:block; margin:1em 0'> -Most people start at our website which has the main PG search -facility: <a href="https://www.gutenberg.org">www.gutenberg.org</a>. -</div> - -<div style='display:block; margin:1em 0'> -This website includes information about Project Gutenberg™, -including how to make donations to the Project Gutenberg Literary -Archive Foundation, how to help produce our new eBooks, and how to -subscribe to our email newsletter to hear about new eBooks. -</div> - -</div> -</body> -</html> diff --git a/old/69062-h/images/fig1.jpg b/old/69062-h/images/fig1.jpg Binary files differdeleted file mode 100644 index 31606bc..0000000 --- a/old/69062-h/images/fig1.jpg +++ /dev/null diff --git a/old/69062-h/images/fig2.jpg b/old/69062-h/images/fig2.jpg Binary files differdeleted file mode 100644 index 43666f2..0000000 --- a/old/69062-h/images/fig2.jpg +++ /dev/null diff --git a/old/69062-h/images/fig3.jpg b/old/69062-h/images/fig3.jpg Binary files differdeleted file mode 100644 index 40eacad..0000000 --- a/old/69062-h/images/fig3.jpg +++ /dev/null diff --git a/old/69062-h/images/fig4.jpg b/old/69062-h/images/fig4.jpg Binary files differdeleted file mode 100644 index 6b2f062..0000000 --- a/old/69062-h/images/fig4.jpg +++ /dev/null diff --git a/old/69062-h/images/fig5.jpg b/old/69062-h/images/fig5.jpg Binary files differdeleted file mode 100644 index f311b9f..0000000 --- a/old/69062-h/images/fig5.jpg +++ /dev/null diff --git a/old/69062-h/images/fig5lge.jpg b/old/69062-h/images/fig5lge.jpg Binary files differdeleted file mode 100644 index 82b87a7..0000000 --- a/old/69062-h/images/fig5lge.jpg +++ /dev/null diff --git a/old/69062-h/images/i_cover.jpg b/old/69062-h/images/i_cover.jpg Binary files differdeleted file mode 100644 index 8725680..0000000 --- a/old/69062-h/images/i_cover.jpg +++ /dev/null diff --git a/old/69062-h/images/pl1a.jpg b/old/69062-h/images/pl1a.jpg Binary files differdeleted file mode 100644 index 243891d..0000000 --- a/old/69062-h/images/pl1a.jpg +++ /dev/null diff --git a/old/69062-h/images/pl1alge.jpg b/old/69062-h/images/pl1alge.jpg Binary files differdeleted file mode 100644 index 34cb300..0000000 --- a/old/69062-h/images/pl1alge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl1b.jpg b/old/69062-h/images/pl1b.jpg Binary files differdeleted file mode 100644 index a0eca03..0000000 --- a/old/69062-h/images/pl1b.jpg +++ /dev/null diff --git a/old/69062-h/images/pl1blge.jpg b/old/69062-h/images/pl1blge.jpg Binary files differdeleted file mode 100644 index 7f5d5f6..0000000 --- a/old/69062-h/images/pl1blge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl2a.jpg b/old/69062-h/images/pl2a.jpg Binary files differdeleted file mode 100644 index ee9f102..0000000 --- a/old/69062-h/images/pl2a.jpg +++ /dev/null diff --git a/old/69062-h/images/pl2alge.jpg b/old/69062-h/images/pl2alge.jpg Binary files differdeleted file mode 100644 index 05d9de7..0000000 --- a/old/69062-h/images/pl2alge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl2b.jpg b/old/69062-h/images/pl2b.jpg Binary files differdeleted file mode 100644 index dd774d0..0000000 --- a/old/69062-h/images/pl2b.jpg +++ /dev/null diff --git a/old/69062-h/images/pl2blge.jpg b/old/69062-h/images/pl2blge.jpg Binary files differdeleted file mode 100644 index 1c26edf..0000000 --- a/old/69062-h/images/pl2blge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl3a.jpg b/old/69062-h/images/pl3a.jpg Binary files differdeleted file mode 100644 index 0fa9d57..0000000 --- a/old/69062-h/images/pl3a.jpg +++ /dev/null diff --git a/old/69062-h/images/pl3alge.jpg b/old/69062-h/images/pl3alge.jpg Binary files differdeleted file mode 100644 index 7efc40a..0000000 --- a/old/69062-h/images/pl3alge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl3b.jpg b/old/69062-h/images/pl3b.jpg Binary files differdeleted file mode 100644 index 74b8439..0000000 --- a/old/69062-h/images/pl3b.jpg +++ /dev/null diff --git a/old/69062-h/images/pl3blge.jpg b/old/69062-h/images/pl3blge.jpg Binary files differdeleted file mode 100644 index c0b4869..0000000 --- a/old/69062-h/images/pl3blge.jpg +++ /dev/null diff --git a/old/69062-h/images/pl4.jpg b/old/69062-h/images/pl4.jpg Binary files differdeleted file mode 100644 index a5b5a28..0000000 --- a/old/69062-h/images/pl4.jpg +++ /dev/null diff --git a/old/69062-h/images/seal.jpg b/old/69062-h/images/seal.jpg Binary files differdeleted file mode 100644 index d0e5f08..0000000 --- a/old/69062-h/images/seal.jpg +++ /dev/null |
