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+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.
+
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+Project Gutenberg (https://www.gutenberg.org) public repository for
+eBook #65569 (https://www.gutenberg.org/ebooks/65569)
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-The Project Gutenberg eBook of Histology of medicinal plants, by William
-Mansfield
-
-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: Histology of medicinal plants
-
-Author: William Mansfield
-
-Release Date: June 8, 2021 [eBook #65569]
-
-Language: English
-
-Character set encoding: UTF-8
-
-Produced by: Peter Becker, Susan Carr and the Online Distributed
-             Proofreading Team at https://www.pgdp.net (This file was
-             produced from images generously made available by The Internet
-             Archive)
-
-*** START OF THE PROJECT GUTENBERG EBOOK HISTOLOGY OF MEDICINAL PLANTS ***
-
-
-
-
-                            HISTOLOGY OF
-                          MEDICINAL PLANTS
-
-                                 BY
-
-                  WILLIAM MANSFIELD, A.M., PHAR.D.
-
-
-        Professor of Histology and Pharmacognosy, College of
-                  Pharmacy of the City of New York
-                         Columbia University
-
-
-                     TOTAL ISSUE, FOUR THOUSAND
-
-
-                              NEW YORK
-                       JOHN WILEY & SONS, INC.
-                   LONDON: CHAPMAN & HALL, LIMITED
-
-
-
-
-                         Copyright, 1916, by
-                          WILLIAM MANSFIELD
-
-
-
-
-                               PREFACE
-
-
-The object of the book is to provide a practical scientific course in
-vegetable histology for the use of teachers and students in schools
-and colleges.
-
-The medicinal plants are studied in great detail because they
-constitute one of the most important groups of economic plants. The
-cells found in these plants are typical of the cells occurring in
-the vegetable kingdom; therefore the book should prove a valuable
-text-book for all students of histology.
-
-The book contains much that is new. In Part II, which is devoted
-largely to the study of cells and cell contents, is a new scientific,
-yet practical, classification of cells and cell contents. The author
-believes that his classification of bast fibres and hairs will clear
-up much of the confusion that students have experienced when studying
-these structures.
-
-The book is replete with illustrations, all of which are from
-original drawings made by the author. As most of these illustrations
-are diagnostic of the plants in which they occur, they will prove
-especially valuable as reference plates.
-
-The material of the book is the outgrowth of the experience of the
-author in teaching histology at the College of Pharmacy of the
-City of New York, Columbia University, and of years of practical
-experience gained by examining powdered drugs in the laboratory of a
-large importing and exporting wholesale drug house.
-
-The author is indebted to Ernest Leitz and Bausch & Lomb Optical
-Company for the use of cuts of microscopic apparatus used in Part I
-of the book.
-
-The author also desires to express his appreciation to Professor
-Walter S. Cameron, who has rendered him much valuable aid.
-
-                                                   WILLIAM MANSFIELD.
-
-  COLUMBIA UNIVERSITY,
-    September, 1916.
-
-
-
-
-                              CONTENTS
-
-
-                               PART I
-
-           SIMPLE AND COMPOUND MICROSCOPES AND MICROSCOPIC
-                               TECHNIC
-
-
-                              CHAPTER I
-
-                       THE SIMPLE MICROSCOPES
-
-                                                                   PAGE
-
-  Simple microscopes, forms of                                       4
-
-
-                             CHAPTER II
-
-                        COMPOUND MICROSCOPES
-
-  Compound microscopes, structure of                                 7
-  Compound microscopes, mechanical parts of                          7
-  Compound microscopes, optical parts of                             9
-  Compound microscopes, forms of                                    12
-
-
-                             CHAPTER III
-
-                      MICROSCOPIC MEASUREMENTS
-
-  Ocular micrometer                                                 19
-  Stage micrometer                                                  19
-  Mechanical stage                                                  21
-  Micrometer eye-pieces                                             21
-  Camera lucida                                                     22
-  Drawing apparatus                                                 23
-  Microphotographic apparatus                                       24
-
-
-                             CHAPTER IV
-
-                      HOW TO USE THE MICROSCOPE
-
-  Illumination                                                      26
-  Micro lamp                                                        27
-  Care of the microscope                                            28
-  Preparation of specimens for cutting                              28
-  Paraffin imbedding oven                                           30
-  Paraffin blocks                                                   31
-  Cutting sections                                                  31
-  Hand microtome                                                    31
-  Machine microtomes                                                32
-
-
-                              CHAPTER V
-
-                              REAGENTS
-
-  Reagent set                                                       39
-  Measuring cylinder                                                40
-
-
-                             CHAPTER VI
-
-                       HOW TO MOUNT SPECIMENS
-
-  Temporary mounts                                                  41
-  Permanent mounts                                                  41
-  Cover glasses                                                     43
-  Glass slides                                                      44
-  Forceps                                                           45
-  Needles                                                           46
-  Scissors                                                          46
-  Turntable                                                         46
-  Labeling                                                          47
-  Preservation of mounted specimens                                 48
-  Slide box                                                         48
-  Slide tray                                                        48
-  Slide cabinet                                                     49
-
-
-                               PART II
-
-                  TISSUES, CELLS AND CELL CONTENTS
-
-
-                              CHAPTER I
-
-                              THE CELL
-
-  Typical cell                                                      53
-  Changes in a cell undergoing division                             55
-  Origin of multicellular plants                                    57
-
-
-                             CHAPTER II
-
-                     THE EPIDERMIS AND PERIDERM
-
-  Leaf epidermis                                                    59
-  Testa epidermis                                                   63
-  Plant hairs                                                       66
-  Forms of hairs                                                    67
-  Papillæ                                                           67
-  Unicellular hairs                                                 69
-  Multicellular hairs                                               72
-  Periderm                                                          80
-  Cork periderm                                                     80
-  Stone cell periderm                                               85
-  Parenchyma and stone cell periderm                                85
-
-
-                             CHAPTER III
-
-                         MECHANICAL TISSUES
-
-  Bast fibres                                                       89
-  Crystal bearing bast fibres                                       90
-  Porous and striated bast fibres                                   92
-  Porous and non-striated bast fibres                               96
-  Non-porous and striated bast fibres                               96
-  Non-porous and non-striated bast fibres                           96
-  Occurrence of bast fibres in powdered drugs                      103
-  Wood fibres                                                      104
-  Collenchyma cells                                                106
-  Stone cells                                                      109
-  Endodermal cells                                                 116
-  Hypodermal cells                                                 118
-
-
-                             CHAPTER IV
-
-                          ABSORPTION TISSUE
-
-  Root hairs                                                       121
-
-
-                              CHAPTER V
-
-                          CONDUCTING TISSUE
-
-  Vessels and tracheids                                            126
-  Annular vessels                                                  127
-  Spiral vessels                                                   127
-  Sclariform vessels                                               128
-  Reticulate vessels                                               131
-  Pitted vessels                                                   131
-  Pitted vessels with bordered pores                               131
-  Sieve tubes                                                      136
-  Sieve plate                                                      138
-  Medullary bundles, rays and cells                                138
-  Medullary ray bundle                                             139
-  The medullary ray                                                139
-  The medullary ray cell                                           141
-  Structure of the medullary ray cells                             142
-  Arrangement of the medullary ray cells in the medullary ray      142
-  Latex tubes                                                      142
-  Parenchyma                                                       144
-  Cortical parenchyma                                              147
-  Pith parenchyma                                                  147
-  Leaf parenchyma                                                  150
-  Aquatic plant parenchyma                                         150
-  Wood parenchyma                                                  150
-  Phloem parenchyma                                                150
-  Palisade parenchyma                                              150
-
-
-                             CHAPTER VI
-
-                           AERATING TISSUE
-
-  Water pores                                                      151
-  Stomata                                                          151
-  Relation of stomata to the surrounding cells                     154
-  Lenticels                                                        157
-  Intercellular spaces                                             158
-
-
-                             CHAPTER VII
-
-                          SYNTHETIC TISSUE
-
-  Photosynthetic tissue                                            163
-  Glandular tissue                                                 164
-  Glandular hairs                                                  164
-  Secretion cavities                                               166
-  Schizogenous cavities                                            168
-  Lysigenous cavities                                              168
-  Schizo-lysigenous cavities                                       168
-
-
-                            CHAPTER VIII
-
-                           STORAGE TISSUE
-
-  Storage cells                                                    173
-  Storage cavities                                                 176
-  Crystal cavities                                                 176
-  Mucilage cavities                                                176
-  Latex cavities                                                   176
-  Oil cavity                                                       178
-  Glandular hairs as storage organs                                178
-  Storage walls                                                    179
-
-
-                             CHAPTER IX
-
-                            CELL CONTENTS
-
-  Chlorophyll                                                      182
-  Leucoplastids                                                    183
-  Starch grains                                                    183
-      Occurrence                                                   184
-      Outline                                                      185
-      Size                                                         185
-      Hilum                                                        185
-      Nature of hilum                                              188
-  Inulin                                                           194
-  Mucilage                                                         194
-  Hesperidin                                                       196
-  Volatile oil                                                     196
-  Tannin                                                           196
-  Aleurone grains                                                  197
-      Structure of aleurone grains                                 197
-      Form of aleurone grains                                      197
-      Description of aleurone grains                               198
-      Tests for aleurone grains                                    198
-  Crystals                                                         200
-      Micro-crystals                                               200
-      Raphides                                                     200
-      Rosette crystals                                             202
-      Solitary crystals                                            205
-  Cystoliths                                                       210
-      Forms of cystoliths                                          210
-      Tests for cystoliths                                         215
-
-
-                              PART III
-
-             HISTOLOGY OF ROOTS, RHIZOMES, STEMS, BARKS,
-                  WOODS, FLOWERS, FRUITS AND SEEDS
-
-
-                              CHAPTER I
-
-                         ROOTS AND RHIZOMES
-
-  Cross-section of pink root                                       219
-  Cross-section of ruellia root                                    219
-  Cross-section of spigelia rhizome                                223
-  Cross-section of ruellia rhizome                                 226
-      Powdered pink root                                           227
-      Powdered ruellia root                                        227
-
-
-                             CHAPTER II
-
-                                STEMS
-
-  Herbaceous stems                                                 233
-  Cross-section, spigelia stem                                     233
-  Ruellia stem                                                     235
-  Powdered horehound                                               237
-  Powdered spurious horehound                                      237
-  Insect flower stems                                              241
-
-
-                             CHAPTER III
-
-                             WOODY STEMS
-
-  Buchu stem                                                       242
-  Mature buchu stem                                                242
-  Powdered buchu stem                                              245
-
-
-                             CHAPTER IV
-
-                                BARKS
-
-  White pine bark                                                  248
-  Powdered white pine bark                                         250
-
-
-                              CHAPTER V
-
-                                WOODS
-
-  Cross-section quassia                                            254
-  Radial-section quassia                                           254
-  Tangential-section quassia                                       258
-
-
-                             CHAPTER VI
-
-                               LEAVES
-
-  Klip buchu                                                       260
-  Powdered klip buchu                                              262
-  Mountain laurel                                                  264
-  Trailing arbutus                                                 264
-
-
-                             CHAPTER VII
-
-                               FLOWERS
-
-  Pollen grains                                                    270
-  Non-spiny-walled pollen grains                                   273
-  Spiny-walled pollen grains                                       273
-  Stigma papillæ                                                   274
-  Powdered insect flowers                                          278
-  Open insect flowers                                              280
-  Powdered white daisies                                           282
-
-
-                            CHAPTER VIII
-
-                               FRUITS
-
-  Celery fruit                                                     285
-
-
-                             CHAPTER IX
-
-                                SEEDS
-
-  Sweet almonds                                                    289
-
-
-                              CHAPTER X
-
-                   ARRANGEMENT OF VASCULAR BUNDLES
-
-  Types of fibro-vascular bundles                                  292
-  Radial vascular bundles                                          292
-  Concentric vascular bundles                                      295
-  Collateral vascular bundles                                      295
-  Bi-collateral vascular bundles                                   298
-  Open collateral vascular bundles                                 298
-
-
-                                INDEX
-
-
-
-
-                       TABLE OF ILLUSTRATIONS
-
-                                                                   PAGE
-  FIG.  1.  Tripod Magnifier                                         4
-  FIG.  2.  Watchmaker’s Loupe                                       4
-  FIG.  3.  Folding Magnifier                                        4
-  FIG.  4.  Reading Glass                                            4
-  FIG.  5.  Steinheil Aplanatic Lens                                 5
-  FIG.  6.  Dissecting Microscope                                    5
-  FIG.  7.  Compound Microscope of Robert Hooke                      8
-  FIG.  8.  Compound Microscope                                     10
-  FIG.  9.  Abbé Condenser                                          11
-  FIG. 10.                                                          11
-  FIG. 11.                                                          11
-  FIG. 12.  Objectives                                              11
-  FIG. 13.                                                          12
-  FIG. 14.                                                          12
-  FIG. 15.  Eye-Pieces.                                             12
-  FIG. 16.  Pharmacognostic Microscope                              12
-  FIG. 17.  Research Microscope                                     14
-  FIG. 18.  Special Research Microscope                             14
-  FIG. 19.  Greenough  Binocular Microscope                         15
-  FIG. 20.  Polarization Microscope                                 16
-  FIG. 21.  Ocular Micrometer                                       19
-  FIG. 22.  Stage Micrometer                                        19
-  FIG. 23.  Micrometer Eye-Piece                                    20
-  FIG. 24.  Micrometer Eye-Piece                                    21
-  FIG. 25.  Mechanical Stage                                        22
-  FIG. 26.  Camera Lucida                                           22
-  FIG. 27.  Camera Lucida                                           22
-  FIG. 28.  Drawing Apparatus                                       23
-  FIG. 29.  Microphotographic Apparatus                             24
-  FIG. 30.  Micro Lamp                                              27
-  FIG. 31.  Paraffin-embedding Oven                                 30
-  FIG. 32.  Paraffin Blocks                                         31
-  FIG. 33.  Hand Microtome                                          31
-  FIG. 34.  Hand Cylinder Microtome                                 34
-  FIG. 35.  Hand Table Microtome                                    34
-  FIG. 36.  Base Sledge Microtome                                   35
-  FIG. 37.  Minot Rotary Microtome                                  36
-  FIG. 38.  Reagent Set                                             39
-  FIG. 39.  Measuring Cylinder                                      40
-  FIG. 40.  Staining Dish                                           40
-  FIG. 41.  Round Cover Glass                                       44
-  FIG. 42.  Square Cover Glass                                      44
-  FIG. 43.  Rectangular Cover Glass                                 44
-  FIG. 44.  Glass Slide                                             44
-  FIG. 45.  Histological Forceps                                    45
-  FIG. 46.  Forceps                                                 45
-  FIG. 47.  Sliding-pin Forceps                                     45
-  FIG. 48.  Dissecting Needle                                       46
-  FIG. 49.  Scissors                                                46
-  FIG. 50.  Scalpels                                                47
-  FIG. 51.  Turntable                                               47
-  FIG. 52.  Slide Box                                               48
-  FIG. 53.  Slide Tray                                              48
-  FIG. 54.  Slide Cabinet                                           49
-
-  PLATE   1  THE ONION ROOT                                         56
-  PLATE   2  LEAF EPIDERMIS                                         60
-  PLATE   3  LEAF EPIDERMIS                                         61
-  PLATE   4  TESTA EPIDERMAL CELLS                                  64
-  PLATE   5  TESTA CELLS                                            65
-  PLATE   6  PAPILLÆ                                                68
-  PLATE   7  UNICELLULAR SOLITARY HAIRS                             70
-  PLATE   8  CLUSTERED UNICELLULAR HAIRS                            71
-  PLATE   9  MULTICELLULAR UNISERIATE NON-BRANCHED HAIRS            73
-  PLATE  10  MULTICELLULAR MULTISERIATE NON-BRANCHED HAIRS          75
-  PLATE  11  MULTICELLULAR UNISERIATE BRANCHED HAIRS                76
-  PLATE  12  NON-GLANDULAR MULTICELLULAR HAIRS                      78
-  PLATE  13  MULTICELLULAR MULTISERIATE BRANCHED HAIRS              79
-  PLATE  14  MULTICELLULAR MULTISERIATE BRANCHED HAIRS              81
-  PLATE  15  MULTICELLULAR MULTISERIATE BRANCHED HAIRS              82
-  PLATE  16  PERIDERM OF CASCARA SAGRADA (_Rhamnus purshiana_,
-               D.C.)                                                84
-  PLATE  17  MANDRAKE RHIZOME and WHITE CINNAMON                    86
-  PLATE  18  PERIDERM OF WHITE OAK (_Quercus alba_, L.)             87
-  PLATE  19  CRYSTAL-BEARING FIBRES OF BARKS                        91
-  PLATE  20  CRYSTAL-BEARING FIBRES OF BARKS                        93
-  PLATE  21  CRYSTAL-BEARING FIBRES OF LEAVES                       94
-  PLATE  22  BRANCHED BAST FIBRES                                   95
-  PLATE  23  POROUS AND STRIATED BAST FIBRES                        97
-  PLATE  24  POROUS AND NON-STRIATED BAST FIBRES                    98
-  PLATE  25  NON-POROUS AND STRIATED BAST FIBRES                    99
-  PLATE  26  NON-POROUS AND NON-STRIATED BAST FIBRES               101
-  PLATE  27  GROUPS OF BAST FIBRES                                 102
-  PLATE  28  WOOD FIBRES                                           105
-  PLATE  29  CATNIP STEM and MOTHERWORT STEM                       107
-  PLATE  30  COLLENCHYMA CELLS                                     108
-  PLATE  31  BRANCHED STONE CELLS                                  110
-  PLATE  32  POROUS AND STRIATED STONE CELLS                       113
-  PLATE  33  POROUS AND NON-STRIATED STONE CELLS                   114
-  PLATE  34  CINNAMON, RUELLA ROOT, CASCARA and CINNAMON           115
-  PLATE  35  CROSS-SECTIONS OF ENDODERMAL CELLS OF                 117
-  PLATE  36  LONGITUDINAL SECTIONS OF ENDODERMAL CELLS             119
-  PLATE  37  HYPODERMAL CELLS                                      120
-  PLATE  38  CROSS-SECTION OF SARSAPARILLA ROOT (_Smilax
-               officinalis_, Kunth)                                123
-  PLATE  39  ROOT HAIRS (Fragments)                                124
-  PLATE  40  ANNULAR AND SPIRAL VESSELS                            129
-  PLATE  41  SPIRAL VESSELS                                        130
-  PLATE  42  SCLARIFORM VESSELS                                    132
-  PLATE  43  RETICULATE VESSELS                                    133
-  PLATE  44  PITTED VESSELS                                        134
-  PLATE  45  VESSELS                                               135
-  PLATE  46  SIEVE TUBE                                            137
-  PLATE  47  RADIAL LONGITUDINAL SECTION OF WHITE SANDALWOOD
-               (_Santalum album_, L.)                              140
-  PLATE  48  KAVA-KAVA ROOT and WHITE PINE BARK                    143
-  PLATE  49  BLACK INDIAN HEMP and BLACK INDIAN HEMP ROOT          145
-  PLATE  50  LATEX VESSELS                                         146
-  PLATE  51  PARENCHYMA CELLS                                      148
-  PLATE  52  GRINDELIA STEM (longitudinal) and GRINDELIA STEM
-               (cross-section)                                     149
-  PLATE  53  ACONITE STEM and PEPPERMINT STEM                      152
-  PLATE  54  TYPES OF STOMA                                        153
-  PLATE  55  LEAF EPIDERMI WITH STOMA                              155
-  PLATE  56  BELLADONNA LEAF, DEER TONGUE LEAF and WHITE PINE LEAF 156
-  PLATE  57  ELDER BARK                                            159
-  PLATE  58  INTERCELLULAR AIR SPACES                              160
-  PLATE  59  IRREGULAR INTERCELLULAR AIR SPACES                    161
-  PLATE  60  GLANDULAR HAIRS                                       165
-  PLATE  61  STALKED GLANDULAR HAIRS                               167
-  PLATE  62  CALAMUS RHIZOME and WHITE PINE BARK                   169
-  PLATE  63  CANELLA ALBA BARK and KLIP BUCHU LEAF                 170
-  PLATE  64  BITTER ORANCE PEEL and WHITE PINE LEAF                171
-  PLATE  65  CINNAMON, CALUMBA, PARENCHYMA, SARSAPARILLA,
-               LEPTANDRA, QUEBRACHO, BLACKBERRY                    174
-  PLATE  66  MUCILAGE AND RESIN                                    175
-  PLATE  67  CROSS-SECTION OF SKUNK-CABBAGE LEAF (_Symplocarpus
-               fœtidus_, [L.] Nutt.)                               177
-  PLATE  68  RESERVE CELLULOSE                                     180
-  PLATE  69  RESERVE CELLULOSE                                     181
-  PLATE  70  STARCH                                                186
-  PLATE  71  STARCH                                                187
-  PLATE  72  STARCH                                                189
-  PLATE  73  STARCH                                                190
-  PLATE  74  STARCH                                                191
-  PLATE  75  STARCH GRAINS                                         192
-  PLATE  76  STARCH MASSES                                         193
-  PLATE  77  INULIN (_Inula helenium_, L.)                         195
-  PLATE  77_a_  ALEURONE GRAINS                                    199
-  PLATE  78  MICRO-CRYSTALS                                        201
-  PLATE  79  RAPHIDES                                              203
-  PLATE  80  ROSETTE CRYSTALS                                      204
-  PLATE  81  INCLOSED ROSETTE CRYSTALS                             206
-  PLATE  82  SOLITARY CRYSTAL                                      207
-  PLATE  83  SOLITARY CRYSTALS                                     208
-  PLATE  84  SOLITARY CRYSTALS                                     209
-  PLATE  85  SOLITARY CRYSTALS                                     211
-  PLATE  86  SOLITARY CRYSTALS                                     212
-  PLATE  87  ROSETTE CRYSTALS AND SOLITARY CRYSTALS OCCURRING IN   213
-  PLATE  88  CYSTOLITHS                                            214
-  PLATE  89  CROSS-SECTION OF ROOT OF SPIGELIA MARYLANDICA, L.     220
-  PLATE  90  RUELLIA ROOT (_Ruellia ciliosa_, Pursh.).             222
-  PLATE  91  CROSS-SECTION OF RHIZOME OF SPIGELIA MARYLANDICA, L.  224
-  PLATE  92  CROSS-SECTION OF RHIZOME OF RUELLIA CILIOSA, Pursh.   225
-  PLATE  93  POWDERED SPIGELIA MARYLANDICA, L.                     228
-  PLATE  94  POWDERED RUELLIA CILIOSA, Pursh.                      229
-  PLATE  95  CROSS-SECTION OF STEM OF SPIGELIA MARYLANDICA, L.     234
-  PLATE  96  CROSS-SECTION OF STEM OF RUELLIA CILIOSA, Pursh.      236
-  PLATE  97  POWDERED HOREHOUND (_Marrubium vulgare_, L).          238
-  PLATE  98  SPURIOUS HOREHOUND (_Marrubium peregrinum_, L.)       239
-  PLATE  99  POWDERED INSECT FLOWER STEMS (_Chrysanthemum
-               cinerariifolium_, [Trev.], Vis.)                    240
-  PLATE 100  CROSS-SECTION OF BUCHU STEMS (_Barosma betulina_
-               [Berg.], Barth, and Wendl.)                         243
-  PLATE 101  BUCHU STEM and LEPTANDRA RHIZOME                      244
-  PLATE 102  POWDERED BUCHU STEMS (_Barosma betulina_ [Berg.],
-                Barth. and Wendl.).                                246
-  PLATE 103  CROSS-SECTION OF UNROSSED WHITE PINE BARK (_Pinus
-               strobus_, L.)                                       249
-  PLATE 104  POWDERED WHITE PINE BARK (_Pinus strobus_, L.)        251
-  PLATE 105  CROSS-SECTION OF QUASSIA WOOD (_Picræna excelsa_
-               [Sw.], Lindl.)                                      255
-  PLATE 106  TANGENTIAL SECTION OF QUASSIA WOOD (_Picræna
-               excelsa_ [Sw.], Lindl.)                             256
-  PLATE 107  RADIAL SECTION OF QUASSIA WOOD (_Picræna excelsa_
-               [Sw.], Lindl.)                                      257
-  PLATE 108  CROSS-SECTION OF KLIP BUCHU JUST OVER THE VEIN        261
-  PLATE 109  POWDERED KLIP BUCHU                                   263
-  PLATE 110  CROSS-SECTION MOUNTAIN LAUREL (_Kalmia latifolia_,
-               L.)                                                 265
-  PLATE 111  CROSS-SECTION TRAILING ARBUTUS LEAF (_Epigæa
-               repens_, L.)                                        266
-  PLATE 112  POWDERED INSECT FLOWER LEAVES                         268
-  PLATE 113  SMOOTH-WALLED POLLEN GRAINS                           271
-  PLATE 114  SPINY WALLED POLLEN GRAINS                            272
-  PLATE 115  PAPILLÆ                                               275
-  PLATE 116  PAPILLÆ OF STIGMAS                                    276
-  PLATE 117  PAPILLÆ OF STIGMAS                                    277
-  PLATE 118  POWDERED CLOSED INSECT FLOWER                         279
-  PLATE 119  POWDERED OPEN INSECT FLOWER                           281
-  PLATE 120  POWDERED WHITE DAISIES (_Chrysanthemum
-               leucanthemum_, L.)                                  283
-  PLATE 121  CROSS-SECTION OF CELERY FRUIT (_Apium
-               graveolens_, L.)                                    286
-  PLATE 121  CROSS-SECTION OF CELERY FRUIT (_Apium
-               graveolens_, L.)                                    286
-  PLATE 123  CROSS-SECTION SWEET ALMOND SEED                       290
-  PLATE 124  CROSS-SECTION OF A RADIAL VASCULAR BUNDLE OF
-               SKUNK CABBAGE ROOT                                  293
-  PLATE 125  CROSS-SECTION OF A PHLOEM-CENTRIC BUNDLE OF
-               CALAMUS RHIZOME (_Acorus calamus_, L.)              294
-  PLATE 126  CROSS-SECTION OF A CLOSED COLLATERAL BUNDLE OF
-               MANDRAKE STEM (_Podophyllum peltatum_, L.)          286
-  PLATE 127  BI-COLLATERAL BUNDLE OF PUMPKIN STEM (_Curcurbita
-               pepo_, L.)                                          297
-
-
-
-
-                               Part I
-
-       SIMPLE AND COMPOUND MICROSCOPES AND MICROSCOPIC TECHNIC
-
-
-
-
-                              CHAPTER I
-
-                       THE SIMPLE MICROSCOPES
-
-
-The construction and use of the =simple microscope= (magnifiers)
-undoubtedly date back to very early times. There is sufficient
-evidence to prove that spheres of glass were used as burning spheres
-and as magnifiers by people antedating the Greeks and Romans.
-
-The simple microscopes of to-day have a very wide range of
-application and a corresponding variation in structure and in
-appearance.
-
-Simple microscopes are used daily in classifying and studying crude
-drugs, testing linen and other cloth, repairing watches, in reading,
-and identifying insects. The more complex simple microscopes are used
-in the dissection and classification of flowers.
-
-The =watchmaker’s loupe=, the =linen tester=, the =reading glass=,
-the =engraver’s lens=, and the simplest folding magnifiers consist
-of a double convex lens. Such a lens produces an erect, enlarged
-image of the object viewed when the lens is placed so that the object
-is within its focal distance. The focal distance of a lens varies
-according to the curvature of the lens. The greater the curvature,
-the shorter the focal distance and the greater the magnification.
-
-The more complicated simple microscope consists of two or more
-lenses. The double and triple magnifiers consist of two and three
-lenses respectively.
-
-When an object is viewed through three lenses, the magnification is
-greater than when viewed through one or two lenses, but a smaller
-part of the object is magnified.
-
-
-                     FORMS OF SIMPLE MICROSCOPES
-
-
-                          TRIPOD MAGNIFIER
-
-The =tripod magnifier= (Fig. 1) is a simple lens mounted on a
-mechanical stand. The tripod is placed over the object and the focus
-is obtained by means of a screw which raises or lowers the lens,
-according to the degree it is magnified.
-
-
-                         WATCHMAKER’S LOUPE
-
-The =watchmaker’s loupe= (Fig. 2) is a one-lens magnifier mounted on
-an ebony or metallic tapering rim, which can be placed over the eye
-and held in position by frowning or contracting the eyelid.
-
-[Illustration: FIG. 1.--Tripod Magnifier]
-
-[Illustration: FIG. 2.--Watchmaker’s Loupe]
-
-
-                          FOLDING MAGNIFIER
-
-The =folding magnifier= (Fig. 3) of one or more lenses is mounted
-in such a way that, when not in use, the lenses fold up like the
-blade of a knife, and when so folded are effectively protected from
-abrasion by the upper and lower surfaces of the folder.
-
-[Illustration: FIG. 3.--Folding Magnifier]
-
-[Illustration: FIG. 4.--Reading Glass]
-
-
-                           READING GLASSES
-
-=Reading glasses= (Fig. 4) are large simple magnifiers, often six
-inches in diameter. The lens is encircled with a metal band and
-provided with a handle.
-
-[Illustration: FIG. 5.--Steinheil Aplanatic Lens]
-
-
-                     STEINHEIL APLANATIC LENSES
-
-=Steinheil aplanatic lenses= (Fig. 5) consist of three or four
-lenses cemented together. The combination is such that the field is
-large, flat, and achromatic. These lenses are suitable for field,
-dissecting, and pocket use. When such lenses are placed in simple
-holders, they make good dissecting microscopes.
-
-[Illustration: FIG. 6.--Dissecting Microscope]
-
-
-                        DISSECTING MICROSCOPE
-
-The =dissecting microscope= (Fig. 6) consists of a Steinheil lens
-and an elaborate stand, a firm base, a pillar, a rack and pinion,
-a glass stage, beneath which there is a groove for holding a metal
-plate with one black and one white surface. The nature of the object
-under observation determines whether a plate is used. When the plate
-is used and when the object is studied by reflected light it is
-sometimes desirable to use the black and sometimes the white surface.
-The mirror, which has a concave and a plain surface, is used to
-reflect the light on the glass stage when the object is studied by
-transmitted light. The dissecting microscope magnifies objects up to
-twenty diameters, or twenty times their real size.
-
-
-
-
-                             CHAPTER II
-
-                        COMPOUND MICROSCOPES
-
-
-The =compound microscope= has undergone wonderful changes since 1667,
-the days of Robert Hooke. When we consider the crude construction
-and the limitations of Robert Hooke’s microscope, we marvel at the
-structural perfection and the unlimited possibilities of the modern
-instrument. The advancement made in most sciences has followed the
-gradual perfection of this instrument.
-
-The illustration of Robert Hooke’s microscope (Fig. 7) will convey
-to the mind more eloquently than words the crudeness of the early
-microscopes, especially when it is compared with the present-day
-microscopes.
-
-
-                STRUCTURE OF THE COMPOUND MICROSCOPE
-
-The parts of the compound microscope (Fig. 8) may be grouped
-into--first, the mechanical, and, secondly, into the optical parts.
-
-
-                        THE MECHANICAL PARTS
-
-1. The =foot= is the basal part, the part which supports all the
-other mechanical and optical parts. The foot should be heavy enough
-to balance the other parts when they are inclined. Most modern
-instruments have a three-parted or tripod-shaped base.
-
-2. The =pillar= is the vertical part of the microscope attached to
-the base. The pillar is joined to the limb by a hinged joint. The
-hinges make it possible to incline the microscope at any angle, thus
-lowering its height. In this way, short, medium, and tall persons
-can use the microscope with facility. The part of the pillar above
-the hinge is called the _limb_. The limb may be either straight
-or curved. The curved form is preferable, since it offers a more
-suitable surface to grasp in transferring from box or shelf to the
-desk, and _vice versa_.
-
-[Illustration: FIG. 7.--Compound Microscope of Robert Hooke]
-
-3. The =stage= is either stationary or movable, round or square, and
-is attached to the limb just above the hinge. The upper surface is
-made of a composition which is not easily attacked by moisture and
-reagents. The centre of the stage is perforated by a circular opening.
-
-4. The =sub-stage= is attached below the stage and is for the purpose
-of holding the iris diaphragm and Abbé condenser. The raising and
-lowering of the sub-stage are accomplished by a rack and pinion.
-
-5. The =iris diaphragm=, which is held in the sub-stage below the
-Abbé condenser, consists of a series of metal plates, so arranged
-that the light entering the microscope may be cut off completely or
-its amount regulated by moving a control pin.
-
-6. The =fine adjustment= is located either at the side or at the top
-of the limb. It consists of a fine rack and pinion, and is used in
-focusing an object when the low-power objective is in position, or in
-finding and focusing the object when the high-power objective is in
-position.
-
-7. The =coarse adjustment= is a rack and pinion used in raising and
-lowering the body-tube and in finding the approximate focus when
-either the high- or low-power objective is in position.
-
-8. The =body-tube= is the path traveled by the rays of light entering
-the objectives and leaving by the eye-piece. To the lower part of the
-tube is attached the nose-piece, and resting in its upper part is the
-draw-tube, which holds the eye-piece. On the outer surface of the
-draw-tube there is a scale which indicates the distance it is drawn
-from the body-tube.
-
-9. The =nose-piece= may be simple, double, or triple, and it is
-protected from dust by a circular piece of metal. Double and triple
-nose-pieces may be revolved, and like the simple nose-piece they hold
-the objectives in position.
-
-
-                          THE OPTICAL PARTS
-
-1. The =mirror= is a sub-stage attachment one surface of which is
-plain and the other concave. The plain surface is used with an Abbé
-condenser when the source of light is distant, while the concave
-surface is used with instruments without an Abbé condenser when the
-source of light is near at hand.
-
-[Illustration: FIG. 8.--Compound Microscope
-
-  Eyepiece
-  Draw Tube
-  Body Tube
-  Coarse
-  Adjustment
-  Revolving Nosepiece for three Objectives
-  Fine Adjustment
-  Stage
-  Objectives
-  Limb
-  Abbi Condenser
-  Iris Diaphragm
-  Hinge for Inclining
-  Substage Attachment
-  Mirror
-  Pillar
-  Foot]
-
-2. The =Abbé condenser= (Fig. 9) is a combination of two or more
-lenses, arranged so as to concentrate the light on the specimen
-placed on the stage. The condenser is located in the opening of the
-stage, and its uppermost surface is circular and flat.
-
-[Illustration: FIG. 9--Abbé Condenser]
-
-3. =Objectives= (Figs. 10, 11, and 12). There are low, medium, and
-high-power objectives. The low-power objectives have fewer and
-larger lenses, and they magnify least, but they show more of the
-object than do the high-power objectives. There are three chief
-types of objectives: First, dry objectives; second, wet objectives,
-of which there are the water-immersion objectives; and third, the
-oil-immersion objectives. The dry objectives are used for most
-histological and pharmacognostical work. For studying smaller objects
-the water objective is sometimes desirable, but in bacteriological
-work the oil-immersion objective is almost exclusively used. The
-globule of water or oil, as the case may be, increases the amount of
-light entering the objective, because the oil and water bend many
-rays into the objective which would otherwise escape.
-
-[Illustration: FIG. 10.]
-
-[Illustration: FIG. 11.]
-
-[Illustration: FIG. 12. Objectives.]
-
-4. =Eye-pieces= (Figs. 13, 14, and 15) are of variable length, but
-structurally they are somewhat similar. The eye-piece consists of a
-metal tube with a blackened inner tube. In the centre of this tube
-there is a small diaphragm for holding the ocular micrometer. In the
-lower end of the tube a lens is fastened by means of a screw. This,
-the field lens, is the larger lens of the ocular. The upper, smaller
-lens is fastened in the tube by a screw, but there is a projecting
-collar which rests, when in position, on the draw-tube.
-
-[Illustration: FIG. 13.]
-
-[Illustration: FIG. 14.]
-
-[Illustration: FIG. 15. Eye-Pieces.]
-
-The longer the tube the lower the magnification. For instance, a
-two-inch ocular magnifies less than an inch and a half, a one-inch
-less than a three-fourths of an inch, etc.
-
-The greater the curvature of the lenses of the ocular the higher will
-be the magnification and the shorter the tube-length.
-
-
-                    FORMS OF COMPOUND MICROSCOPES
-
-The following descriptions refer to three different models of
-compound microscopes: one which is used chiefly as a pharmacognostic
-microscope, one as a research microscope stand, while the third type
-represents a research microscope stand of highest order, which is
-used at the same time for taking microphotographs.
-
-[Illustration: FIG. 16.--Pharmacognostic Microscope]
-
-
-                     PHARMACOGNOSTIC MICROSCOPE
-
-The =pharmacognostic microscope= (Fig. 16) is an instrument
-which embodies only those parts which are most essential for the
-examination of powdered drugs, bacteria, and urinary sediments. This
-microscope is provided with a stage of the dimensions 105 × 105 mm.
-This factor and the distance of 80 mm. from the optical centre to the
-handle arm render it available for the examination of even very large
-objects and preparations, or preparations suspended in glass dishes.
-The stand is furnished with a side micrometer, a fine adjustment
-having knobs on both sides, thereby permitting the manipulation of
-the micrometer screw either by left or right hand. The illuminating
-apparatus consists of the Abbé condenser of numerical aperture
-of 1.20, to which is attached an iris diaphragm for the proper
-adjustment of the light. A worm screw, mounted in connection with the
-condenser, serves for the raising and lowering of the condenser, so
-that the cone of illuminating pencils can be arranged in accordance
-to the objective employed and to the preparation under observation.
-The objectives necessary are those of the achromatic type, possessing
-a focal length of 16.2 mm. and 3 mm. Oculars which render the best
-results in regard to magnification in connection with the two
-objectives mentioned are the Huyghenian eye-pieces II and IV so that
-magnifications are obtained varying from 62 to 625. It is advisable,
-however, to have the microscope equipped with a triple revolving
-nose-piece for the objectives, so that provision is made for the
-addition of an oil-immersion objective at any time later should the
-microscope become available for bacteriological investigations.
-
-
-                       THE RESEARCH MICROSCOPE
-
-The =research microscope= used in research work (Fig. 17) must be
-equipped more elaborately than the microscope especially designed for
-the use of the pharmacognosist. While the simple form of microscope
-is supplied with the small type of Abbé condenser, the research
-microscope is furnished with a large illuminating apparatus of
-which the iris diaphragm is mounted on a rack and pinion, allowing
-displacement obliquely to the optical centre, also to increase
-resolving power in the objectives when observing those objects which
-cannot be revealed to the best advantage with central illumination.
-Another iris is furnished above the condenser; this iris becomes
-available the instant an object is to be observed without the aid
-of the condenser, in which case the upper iris diaphragm allows
-proper adjustment of the light. The mirror, one side plane, the
-other concave, is mounted on a movable bar, along which it can be
-slid--another convenience for the adjustment of the light. The
-microscope stage of this stand is of the round, rotating and centring
-pattern, which permits a limited motion to the object slide: The
-rotation of the microscope stage furnishes another convenience in the
-examination of objects in polarized light, allowing the preparation
-to be rotated in order to distinguish the polarization properties of
-the objects under observation.
-
-[Illustration: FIG. 17.--Research Microscope]
-
-[Illustration: FIG. 18.--Special Research Microscope]
-
-
-                     SPECIAL RESEARCH MICROSCOPE
-
-A =special research microscope= of the highest order (Fig. 18)
-is supplied with an extra large body tube, which renders it of
-special advantage for micro-photography. Otherwise in its mechanical
-equipment it resembles very closely the medium-sized research
-microscope stand, with the exception that the stand is larger in its
-design, therefore offering universal application. In regard to the
-illuminating apparatus, it is advisable to mention that the one in
-the large research microscope stand is furnished with a three-lens
-condenser of a numerical aperture of 1.40, while the medium-sized
-research stand is provided with a two-lens condenser of a numerical
-aperture of 1.20. The stage of the microscope is provided with a
-cross motion--the backward and forward motion of the preparation is
-secured by rack and pinion, while the side motion is controlled by a
-micrometric worm screw. In cases where large preparations are to be
-photographed, the draw-tube with ocular and the slider in which the
-draw-tubes glide are removed to allow the full aperture of wide-angle
-objectives to be made use of.
-
-[Illustration: FIG. 19.--Greenough Binocular Microscope]
-
-
-                        BINOCULAR MICROSCOPE
-
-The =Greenough binocular microscope=, as shown in Fig. 19, consists
-of a microscope stage with two tubes mounted side by side and moving
-on the same rack and pinion for the focusing adjustment. Either tube
-can be used without the other. The oculars are capable of more or
-less separation to suit the eyes of different observers. In each
-of the drub-like mountings, near the point where the oculars are
-introduced, porro-prisms have been placed, which erect the image.
-This microscope gives most perfect stereoscopic images, which are
-erect instead of inverted, as in the monocular compound microscopes.
-The Greenough binocular microscope is especially adapted for
-dissection and for studying objects of considerable thickness.
-
-
-                       POLARIZATION MICROSCOPE
-
-The =polarization microscope= (Fig. 20) is used chiefly for the
-examination of crystals and mineral sections as well as for the
-observation of organic bodies in polarized light. It can, however,
-also be used for the examination of regular biological preparations.
-
-[Illustration: FIG. 20.--Polarization Microscope]
-
-If compared with the regular biological microscope, the polarization
-microscope is found characteristic of the following points: it is
-supplied with a polarization arrangement. The latter consists of a
-polarizer and analyzer. The polarizer is situated in a rotating mount
-beneath the condensing system. The microscope, of which the diagram
-is shown, possesses a triple “Ahrens” prism of calcite. The entering
-light is divided into two polarized parts, situated perpendicularly
-to each other. The so-called “ordinary” rays are reflected to one
-side by total reflection, which takes place on the inner cemented
-surface of the triple prism, allowing the so-called “extraordinary”
-rays to pass through the condenser. If the prism is adjusted to
-its focal point, it is so situated that the vibration plane of the
-extra-ordinary rays are in the same position as shown in the diagram
-of the illustration.
-
-The analyzer is mounted within the microscope-tube above the
-objective. Situated on a sliding plate, it can be shifted into
-the optical axis whenever necessary. The analyzer consists of a
-polarization prism after Glan-Thompson. The polarization plane of the
-active extraordinary rays is situated perpendicularly to the plane as
-shown in the diagram. The polarization prisms are ordinarily crossed.
-In this position the field of the microscope is darkened as long as
-no substance of a double refractive index has been introduced between
-the analyzer and polarizer. In rotating the polarizer up to the mark
-90, the polarization prisms are mounted parallel and the field of
-the microscope is lighted again. Immediately above the analyzer and
-attached to the mounting of the analyzer a lens of a comparatively
-long focal length has been placed in order to overcome the difference
-in focus created by the introduction of the analyzer into the optical
-rays.
-
-The condensing system is mounted on a slider, and, furthermore,
-can be raised and lowered along the optical centre by means of a
-rack-and-pinion adjustment. If lowered sufficiently, the condensing
-system can be thrown to the side to be removed from the optical
-rays. The condenser consists of three lenses. The two upper lenses
-are separately mounted to an arm, which permits them to be tilted to
-one side in order to be removed from the optical rays. The complete
-condenser is used only in connection with high-power objectives.
-As far as low-power objectives are concerned, the lower condensing
-lens alone is made use of, and the latter is found mounted to the
-polarizer sleeve. Below the polarizer and above the lower condensing
-lens an iris diaphragm is found.
-
-The microscope table is graduated on its periphery, and, furthermore,
-carries a vernier for more exact reading.
-
-The polarization microscope is not furnished with an objective
-nose-piece. Every objective, however, is supplied with an individual
-centring head, which permits the objective to be attached to
-an objective clutch-changer, situated at the lower end of the
-microscope-tube. The centring head permits the objectives to be
-perfectly centred and to remain centred even if another objective is
-introduced into the objective clutch-changer.
-
-At an angle of 45 degrees to the polarization plane of polarizer and
-analyzer, a slot has been provided, which serves for the introduction
-of compensators.
-
-Between analyzer and ocular, another slot is found which permits
-the Amici-Bertrand lens to be introduced into the optical axis. The
-slider for the Bertrand lens is supplied with two centring screws
-whereby this lens can be perfectly and easily centred. The Bertrand
-lens serves the purpose of observing the back focal plane of the
-microscope objective. In order to allow the Bertrand lens to be
-focused, the tube can be raised and lowered for this purpose. An iris
-diaphragm is mounted above the Bertrand lens.
-
-If the Bertrand lens is shifted out of the optical axis, one can
-observe the preparation placed upon the microscope stage and,
-depending on its thickness or its double refraction, the interference
-color of the specimen. This interference figure is called the
-orthoscopic image and, accordingly, one speaks of the microscope as
-being used as an “orthoscope.”
-
-After the Bertrand lens has been introduced into the optical axis,
-the interference figure is visible in the back focal plane of the
-objective. Each point of this interference figure corresponds to
-a certain direction of the rays of the preparation itself. This
-arrangement permits observation of the change of the reflection of
-light taking place in the preparation, this in accordance with the
-change of the direction of the rays. This interference figure is
-called the conoscopic image, and, accordingly, the microscope is used
-as a “conoscope.”
-
-Many types of polarization microscopes have been constructed; those
-of a more elaborate form are used for research investigations; others
-of smaller design for routine investigations.
-
-
-
-
-                             CHAPTER III
-
-                      MICROSCOPIC MEASUREMENTS
-
-
-In making critical examinations of powdered drugs, it is frequently
-necessary to measure the elements under observation, particularly in
-the case of starches and crystals.
-
-[Illustration: FIG. 21.--Ocular Micrometer]
-
-
-                          OCULAR MICROMETER
-
-Microscopic measurements are made by the =ocular micrometer= (Fig.
-21). This consists of a circular piece of transparent glass on the
-centre of which is etched a one- or two-millimeter scale divided into
-one hundred or two hundred divisions respectively. The value of each
-line is determined by standardizing with a stage micrometer.
-
-
-                          STAGE MICROMETER
-
-[Illustration: FIG. 22.--Stage Micrometer]
-
-The =stage micrometer= (Fig. 22) consists of a glass slide upon which
-is etched a millimeter scale divided into one hundred equal parts or
-lines: each line has a value of one hundredth of a millimeter.
-
-
-    STANDARDIZATION OF OCULAR MICROMETER WITH LOW-POWER OBJECTIVE
-
-Having placed the ocular micrometer in the eye-piece and the stage
-micrometer on the centre of the stage, focus until the lines of the
-stage micrometer are clearly seen. Then adjust the scales until the
-lines of the stage micrometer are parallel with and directly under
-the lines of the ocular micrometer.
-
-Ascertain the number of lines of the stage micrometer covered by the
-one hundred lines of the ocular micrometer. Then calculate the value
-of each line of the ocular. This is done in the following manner:
-
-If the one hundred lines of the ocular cover seventy-five lines
-of the stage micrometer, then the one hundred lines of the ocular
-micrometer are equivalent to seventy-five one-hundredths, or
-three-fourths, of a millimeter. One line of the ocular micrometer
-will therefore be equivalent to one-hundredth of seventy-five
-one-hundredths, or .0075 part of a millimeter, and as a micron is the
-unit for measuring microscopic objects, this being equivalent to one
-one-thousandth of a millimeter, the value of each line of the ocular
-will therefore be 7.5 microns.
-
-[Illustration: FIG. 23.--Micrometer Eye-Piece]
-
-With the high-power objective in place, ascertain the value of each
-line of the ocular. If one hundred lines of the ocular cover only
-twelve lines of the stage micrometer, then the one hundred lines of
-the ocular are equivalent to twelve one-hundredths of a millimeter,
-the value of one line being equivalent to one one-hundredth of twelve
-one-hundredths, or twelve ten-thousandths of a millimeter, or .0012,
-or 1.2_µ_.
-
-It will therefore be seen that objects as small as a thousandth of a
-millimeter can be accurately measured by the ocular micrometer.
-
-In making microscopic measurements it is only necessary to find how
-many lines of the ocular scale are covered by the object. The number
-of lines multiplied by the equivalent of each line will be the size
-of the object in microns, or _micromillimeters_.
-
-[Illustration: FIG. 24.--Micrometer Eye-Piece]
-
-
-                        MICROMETER EYE-PIECES
-
-=Micrometer eye-pieces= (Figs. 23 and 24) may be used in making
-measurements. These eye-pieces with micrometer combinations are
-preferred by some workers, but the ocular micrometer will meet the
-needs of the average worker.
-
-
-                          MECHANICAL STAGES
-
-Moving objects by hand is tiresome and unsatisfactory, first, because
-of the possibility of losing sight of the object under observation,
-and secondly, because the field cannot be covered so systematically
-as when a mechanical stage is used for moving slides.
-
-The =mechanical stage= (Fig. 25) is fastened to the stage by a screw.
-The slide is held by two clamps. There is a rack and pinion for
-moving the slide to left or right, and another rack and pinion for
-moving the slide forward and backward.
-
-[Illustration: FIG. 25. Mechanical Stage]
-
-
-                            CAMERA LUCIDA
-
-The =camera lucida= is an optical mechanical device for aiding the
-worker in making drawings of microscopic objects. The instrument is
-particularly necessary in research work where it is desirable to
-reproduce an object in all its details. In fact, all reproductions
-illustrating original work should be made by means of the camera
-lucida or by microphotography.
-
-[Illustration: FIG. 26.--Camera Lucida]
-
-[Illustration: FIG. 27.--Camera Lucida]
-
-A great many different types of camera lucidas or drawing apparatus
-are obtainable, varying from simple-inexpensive to complex-expensive
-forms. Figs. 26, 27, and 28 show simple and complex forms.
-
-[Illustration: FIG. 28.--Drawing Apparatus]
-
-
-                     MICROPHOTOGRAPHIC APPARATUS
-
-The =microphotographic apparatus= (Fig. 29), as the name implies, is
-an apparatus constructed in such a manner that it may be attached to
-a microscope when we desire to photograph microscopic objects. It
-consists of a metal base and a polished metal pillar for holding the
-bellows, slide holder, ground-glass observation plate, and eye-piece.
-In making photographs, the small end of the bellows is attached to
-the ocular of the microscope, the focus adjusted, and the object or
-objects photographed. More uniform results are obtained in making
-such photographs if an artificial light of an unvarying candle-power
-is used.
-
-[Illustration: FIG. 29.--Microphotographic Apparatus]
-
-There are obtainable more elaborate microphotographic apparatus than
-the one figured and described, but for most workers this one will
-prove highly satisfactory. It is possible, by inclining the tube of
-the microscope, to make good microphotographs with an ordinary plate
-camera. This is accomplished by removing the lens of the camera and
-attaching the bellows to the ocular, focusing, and photographing.
-
-
-
-
-                             CHAPTER IV
-
-                      HOW TO USE THE MICROSCOPE
-
-
-In beginning work with the compound microscope, place the base of the
-microscope opposite your right shoulder, if you are right-handed; or
-opposite your left shoulder, if you are left-handed. Incline the body
-so that the ocular is on a level with your eye, if necessary; but
-if not, work with the body of the microscope in an erect position.
-In viewing the specimen, keep both eyes open. Use one eye for
-observation and the other for sketching. In this way it will not be
-necessary to remove the observation eye from the ocular unless it be
-to complete the details of a sketch.
-
-=Learn to use both eyes.= Most workers, however, accustom themselves
-to using one eye; when they are sketching, they use both eyes,
-although it is not necessary to do so.
-
-=Open the iris diaphragm=, and incline the mirror so that white light
-is reflected on the Abbé condenser. Place the slide on the centre
-of the stage, and if the slide contains a section of a plant, move
-the slide so as to place this specimen over the centre of the Abbé
-condenser. Then lower the body by means of the coarse adjustment
-until the low-power object, which should always be in position when
-work is begun, is within one-fourth of an inch of the stage. Then
-raise the body by means of the coarse adjustment until the object,
-or objects, in case a powder is being examined, is seen. Open and
-close the iris diaphragm, finally adjusting the opening so that the
-best possible illumination is obtained for bringing out clearly
-the structure of the object or objects viewed. Then regulate the
-focus by moving the body up or down by turning the fine adjustment.
-When studying cross-sections or large particles of powders, it is
-sometimes desirable to make low-power sketches of the specimen. In
-most cases, however, only sufficient time should be spent in studying
-the specimen to give an idea of the size, structure, and general
-arrangement or plan or structure if a section of a plant, or, if
-a powder, to note its striking characters. All the finer details
-of structure are best brought out with the high-power objective in
-position.
-
-In =placing the high-power objective in position=, it is first
-necessary to raise the body by the coarse adjustment; then open the
-iris diaphragm, and lower the body until the objective is within
-about one-eighth of an inch of the slide. Now raise the tube by
-the fine adjustment until the object is in focus, then gradually
-close the iris diaphragm until a clear definition of the object is
-obtained. Now proceed to make an accurate sketch of the object or
-objects being studied.
-
-In =using the water or oil-immersion objectives= it is first
-necessary to place a drop of distilled water or oil, as the case may
-be, immediately over the specimen, then lower the body by the coarse
-adjustment until the lens of the objective touches the water or the
-oil. Raise the tube, regulate the light by the iris diaphragm, and
-proceed as if the high-power objectives were in position.
-
-The water or oil should be removed from the objectives and from the
-slide when not in use.
-
-After the higher-powered objective has been used, the body should
-be raised, and the low-power objective placed in position. If the
-draw-tube has been drawn out during the examination of the object,
-replace it, but be sure to hold one hand on the nose-piece so as to
-prevent scratching the objective and Abbé condenser by their coming
-in forceful contact. Lastly, clean the mirror with a soft piece of
-linen. In returning the microscope to its case, or to the shelf,
-grasp the limb, or the pillar, firmly and carry as nearly vertical as
-possible in order not to dislodge the eye-piece.
-
-
-                            ILLUMINATION
-
-The illumination for microscopic work may be from natural or
-artificial sources.
-
-[Illustration: FIG. 30.--Micro Lamp]
-
-It has been generally supposed that the best possible illumination
-for microscopic work is diffused sunlight obtained from a northern
-direction. No matter from what direction diffused sunlight is
-obtained, it will be found suitable for microscopic work. In no case
-should direct sunlight be used, because it will be found blinding
-in its effects upon the eyes. Natural illumination--diffused
-sunlight--varies so greatly during the different months of the
-year, and even during different periods of the day, that individual
-workers are resorting more and more to artificial illumination. The
-particular advantage of such illumination is due to the fact that
-its quality and intensity are uniform at all times. There are many
-ways of securing such artificial illumination, no one of which has
-any particular advantage over the other. Some workers use an ordinary
-gas or electric light with a color screen placed in the sub-stage
-below the iris diaphragm. In other cases a globe filled with a weak
-solution of copper sulphate is placed in such a way between the
-source of light and the microscope that the light is focused on the
-mirror. Modern mechanical ingenuity has devised, however, a number of
-more convenient micro lamps (Fig. 30). These lamps are a combination
-of light and screen. In some forms a number of different screens come
-with each lamp, so that it is possible to obtain white-, blue-, or
-dark-ground illumination. The type of the screen used will be varied
-according to the nature of the object studied.
-
-
-                       CARE OF THE MICROSCOPE
-
-If possible, the microscope should be stored in a room of the same
-temperature as that in which it is to be used. In any case, avoid
-storing in a room that is cooler than the place of use, because when
-it is brought into a warmer room, moisture will condense on the
-ocular objectives and mirrors.
-
-Before beginning work remove all moisture, dust, etc., from the inner
-and outer lenses of the ocular, the objectives, the Abbé condenser,
-and the mirror by means of a piece of soft, old linen. When the work
-is finished the optical parts should be thoroughly cleaned.
-
-If reagents have been used, be sure that none has got on the
-objectives or the Abbé condenser. If any reagent has got on these
-parts, wash it off with water, and then dry them thoroughly with soft
-linen.
-
-The inner lenses of the eye-pieces and the under lens of the Abbé
-condenser should occasionally be cleaned. The mechanical parts of the
-stand should be cleaned if dust accumulates, and the movable surfaces
-should be oiled occasionally. Never attempt to make new combinations
-of the ocular or objective lenses, or transfer the objectives or
-ocular from one microscope to another, because the lenses of any
-given microscope form a perfect lens system, and this would not be
-the case if they were transferred. Keep clean cloths in a dust-proof
-box. Under no circumstances touch any of the optical parts with your
-fingers.
-
-
-                PREPARATION OF SPECIMENS FOR CUTTING
-
-Most drug plants are supplied to pharmacists in a dried condition.
-It is necessary, therefore, to boil the drug in water, the time
-varying from a few minutes, in the case of thin leaves and herbs, up
-to a half hour if the drug is a thick root or woody stem. If a green
-(undried) drug is under examination, this first step is not necessary.
-
-If the specimen to be cut is a leaf, a flower-petal, or other thin,
-flexible part of a plant, it may be placed between pieces of elder
-pith or slices of carrot or potato before cutting.
-
-
-                       SHORT PARAFFIN PROCESS
-
-In most cases, however, more perfect sections will be obtained if the
-specimens are embedded in paraffin, by the quick paraffin process,
-which is easily carried out.
-
-After boiling the specimen in water, remove the excess of moisture
-from the outer surface with filter paper or wait until the water has
-evaporated. Next make a mould of stiff cardboard and pour melted
-paraffin (melting at 50 or 60 degrees) into the mould to a height of
-about one-half inch, when the paraffin has solidified. This may be
-hastened by floating it on cool or iced water instead of allowing it
-to cool at room temperature.
-
-The specimens to be cut are now placed on the paraffin, with glue, if
-necessary, to hold them in position, and melted paraffin poured over
-the specimens until they are covered to a depth of about one-fourth
-of an inch. Cool on iced water, trim off the outer paraffin to the
-desired depth, and the Specimen will be in a condition suitable for
-cutting.
-
-Good workable sections may be cut from specimens embedded by this
-quick paraffin method. After a little practice the entire process
-can be carried out in less than an hour. This method of preparing
-specimens for cutting will meet every need of the pharmacognosist.
-
-
-                        LONG PARAFFIN PROCESS
-
-In order to bring out the structure of the =protoplast= (living part
-of the cell), it will be necessary to begin with the living part of
-the plant and to use the long paraffin method or the collodion method.
-
-Small fragments of a leaf, stem, or root-tip are placed in
-chromic-acid solution, acetic alcohol, picric acid, chromacetic
-acid, alcohol, etc., depending upon the nature of the specimen under
-observation. The object of placing the living specimen in such
-solutions is to kill the protoplast suddenly so that the parts of the
-cell will bear the same relationship to each other that they did in
-the living plant, and to fix the parts so killed.
-
-After the fixing process is complete, the specimen is freed of the
-fixing agent by washing in water. From the water-bath the specimens
-are transferred successively to 10, 20, 40, 60, 70, 80, 90, and
-finally 100 per cent alcohol. In this 100 per cent alcohol-bath the
-last traces of moisture are removed. The length of time required to
-leave the specimens in the different percentages of alcohols varies
-from a few minutes to twenty-four hours, depending upon the size and
-the nature of the specimen.
-
-[Illustration: FIG. 31.--Paraffin-embedding Oven]
-
-After dehydration the specimen is placed in a clearing
-agent--chloroform or xylol--both of which are suitable when embedding
-in paraffin. The clearing agents replace the alcohol in the cells,
-and at the same time render the tissues transparent. From the
-clearing agent the specimen is placed in a weak solution of paraffin,
-dissolved xylol, or chloroform. The strength of the paraffin solution
-is gradually increased until it consists of pure paraffin. The
-temperature of the paraffin-embedding oven (Fig. 31) should not be
-much higher than the melting-point of the paraffin.
-
-The specimen is now ready to be embedded. First make a mould of
-cardboard or a lead-embedding frame (Fig. 32), melt the paraffin, and
-then place the specimen in a manner that will facilitate cutting.
-Remove the excess of paraffin and cut when desired.
-
-[Illustration: FIG. 32.--Paraffin Blocks]
-
-In using the collodion method for embedding fibrous specimens,
-as wood, bark, roots, etc., the specimen is first fixed with
-picric acid, washed with water, cleared in ether-alcohol, embedded
-successively in two, five, and twelve per cent ether-alcohol
-collodion solution, and finally embedded in a pure collodion bath.
-
-
-                          CUTTING SECTIONS
-
-Specimens prepared as described above may be cut with a hand
-microtome or a machine microtome.
-
-
-                           HAND MICROTOME
-
-In cutting sections by a =hand microtome=, it is necessary to place
-the specimen, embedded in paraffin or held between pieces of elder
-pith, carrot, or potato, over the second joints of the fingers,
-then press the first joints firmly upon the specimen with the thumb
-pressed against it. If they are correctly held, the specimens will be
-just above the level of the finger and the end of the thumb, and the
-joint will be below the level of the finger.
-
-[Illustration: FIG. 33.--Hand Microtome]
-
-Hold the section cutter (Fig. 33) firmly in the hand with the flat
-surface next to the specimen. While cutting the section, press your
-arm firmly against your chest, and bend the wrist nearly at right
-angles to the arm. Push the cutting edge of the microtome toward the
-body and through the specimen in such a way as to secure as thin a
-section as possible. Do not expect to obtain nice, thin sections
-during the first or second trials, but continued practice will enable
-one to become quite efficient in cutting sections in this manner.
-
-When the examination of drugs is a daily occurrence, the above method
-will be found highly satisfactory.
-
-
-                         MACHINE MICROTOMES
-
-When a number of sections are to be prepared from a given specimen,
-it is desirable to cut the sections on a machine microtome,
-particularly when the sections are to be prepared for the use of
-students, in which case they should be as uniform as possible.
-
-Great care should be exercised in cutting sections with a machine
-microtome--first, in the selection of the type of the microtome; and
-secondly, in the style of knife used in cutting.
-
-For soft tissues embedded in paraffin or collodion, the =rotary
-microtome= with vertical knife will give best results. The thickness
-of the specimen is regulated by mechanical means, so that in cutting
-the sections it is only necessary to turn a crank and remove the
-specimens from the knife-edge, unless there is a ribbon-carrier
-attachment. If the sections are being cut from a specimen embedded
-by the quick paraffin method, it is best to drop the section in a
-metal cup partly filled with warm water. This will cause the paraffin
-to straighten out, and the specimen will uncoil. After sufficient
-specimens have been cut, the cup should be placed in a boiling-water
-bath until the paraffin surrounding the sections melts and floats on
-the water. Before removing the specimen from the water-bath, it is
-advisable to shake the glass vigorously in order to cause as many
-specimens as possible to settle to the bottom of the cup. The cup
-is then placed in iced water or set aside until the paraffin has
-solidified. The cake-like mass is then removed from the cup, and the
-sections adhering to its under surface are removed by lifting them
-carefully off with the flat side of the knife and transferring them,
-together with the sections at the bottom of the cup, to a wide-mouth
-bottle, and covered with alcohol, glycerine, and water mixture; or if
-it is desired to stain the specimens, they should be placed in a weak
-alcoholic solution.
-
-Specimens having a hard, woody texture should be cut on a =sliding
-microtome= by means of a special wood knife, which is especially
-tempered to cut woody substances. Woody roots, wood, or thick bark
-may be cut readily on this microtome when they have been embedded by
-the quick paraffin process. The knife in the sliding microtome is
-placed in a horizontal position, slanting so that the knife-edge is
-drawn gradually across the specimen. After cutting, the sections are
-treated as described above.
-
-The thickness of the sections is regulated by mechanical means.
-After a section has been cut, the block containing the specimen is
-raised by turning a thumb-screw. In this microtome the knife, as in
-the rotary type, is fixed, and the block containing the specimen is
-movable.
-
-If the specimen has been infiltrated with, and embedded in, paraffin
-or collodion, the treatment of the sections after cutting should be
-different.
-
-In the case of paraffin, the sections are fastened directly to the
-slide, and the paraffin is dissolved by either chloroform or xylol.
-The specimen is then placed in 100, 95, and 45 per cent alcohol,
-and then washed in water. These sections are now stained with
-water-stains, brought back through alcohol, cleared, and mounted in
-Canada balsam.
-
-If alcoholic stains are used, it will not be necessary to dehydrate
-before staining, and the dehydration after staining will also be
-eliminated.
-
-Sections infiltrated with collodion are either stained directly
-without removing the collodion or after removal.
-
-
-                         FORMS OF MICROTOMES
-
-The =hand cylinder microtome= (Fig. 34) consists of a cylindrical
-body. The clamp for holding the specimen is near the top below the
-cutting surface. At the lower end is attached a micrometer screw with
-a divided milled head. When moved forward one division, the specimen
-is raised 0.01 mm. This micrometer screw has an upward movement of
-10 mm. The cutting surface consists of a cylindrical glass ring.
-
-[Illustration: FIG. 34.--Hand Cylinder Microtome]
-
-[Illustration: FIG. 35.--Hand Table Microtome]
-
-The =hand table microtome= (Fig. 35) is provided with a clamp, by
-which it may be attached to the edge of a table or desk. The cutting
-surface consists of two separated but parallel glass benches. The
-object is held by a clamp and is raised by a micrometer screw, which,
-when moved through one division by turning the divided head, raises
-the specimen 0.01 mm.
-
-The =sliding microtome= has a track of 250 mm. The object is held
-by a clamp and its height regulated by hand. The disk regulating
-the micrometer screw is divided into one hundred parts. When this
-is turned through one division, the object is raised 0.005 mm. or
-5 microns, at the same time a clock-spring in contact with teeth
-registers by a clicking sound. If the disk is turned through two
-divisions, there will be two clicks, etc. In this way is regulated
-the thickness of the sections cut. When the micrometer screw has been
-turned through the one hundred divisions, it must be unscrewed, the
-specimen raised, and the steps of the process repeated. The knife is
-movable and is drawn across the specimen in making sections.
-
-[Illustration: FIG. 36.--Base Sledge Microtome]
-
-The =base sledge microtome= (Fig. 36) has a heavy iron base which
-supports a sliding-way on which the object-carrier moves. The
-object-carrier is mounted on a solid mass of metal, and is provided
-with a clamp for holding the object. The object is raised by turning
-a knob which, when turned once, raises the specimen one to twenty
-microns, according to how the feeding mechanism is set.
-
-Sections thicker than twenty microns may be obtained by turning the
-knob two or more times. The knife is fixed and is supported by two
-pillars, the base of which may be moved forward or backward in such a
-manner that the knife can be arranged with an oblique or right-angled
-cutting surface.
-
-[Illustration: FIG. 37.--Minot Rotary Microtome]
-
-The =Minot rotary microtome= (Fig. 37) has a fixed knife, held in
-position by two pillars, and a movable object-carrier. The object is
-firmly secured by a clamp, and it is raised by a micrometer screw.
-The screw is attached to a wheel having five hundred teeth on its
-periphery. A pawl is adjusted to the teeth in such a way that, when
-moved by turning a wheel to which it is attached, specimens varying
-from one to twenty-five microns in thickness may be cut, according
-to the way the adjusting disk is set. When the mechanism has been
-regulated and the object adjusted for cutting, it is only necessary
-to turn a crank in cutting sections.
-
-
-                         CARE OF MICROTOMES
-
-When not in use, microtomes should be protected from dust, and all
-parts liable to friction should be oiled.
-
-Microtome knives should be honed as often as is necessary to insure
-a proper cutting edge. After cutting objects, the knives should be
-removed, cleaned, and oiled.
-
-It should be kept clearly in mind that special knives are required
-for cutting collodion, paraffin, and frozen and woody sections. The
-cutting edges of the different knives vary considerably, as is shown
-in the preceding cuts.
-
-
-
-
-                              CHAPTER V
-
-                              REAGENTS
-
-
-Little attention is given in the present work to micro-chemical
-reactions for the reason that their value has been much overrated in
-the past. A few reagents will be found useful, however, and these few
-are given, as well as their special use. They are as follows:
-
-
-                          LIST OF REAGENTS
-
-=Distilled Water= is used in the alcohol, glycerine, and water
-mixture as a general mounting medium. It is used when warm as a test
-for inulin and it is used in preparing various reagents.
-
-=Glycerine= is used in preparing the alcohol, glycerine, and water
-mixture, in testing for aleurone grains, and as a temporary mounting
-medium.
-
-=Alcohol= is used in preparing the alcohol, glycerine, and water
-mixture, in testing for volatile oils.
-
-=Acetic Acid=. Both dilute and strong solutions are used in testing
-for aleurone grains, cystoliths, and crystals of calcium oxalate.
-
-=Hydrochloric Acid= is used in connection with phloroglucin as a test
-for lignin and as a test for calcium oxalate.
-
-=Ferric Chloride Solution= is used as a test for tannin.
-
-=Sulphuric Acid= is used as a test for calcium oxalate.
-
-=Tincture Alkana= is used when freshly prepared by macerating the
-granulated root with alcohol and filtering, as a test for resin.
-
-=Sodium Hydroxide=. A five per cent solution is used as a test for
-suberin and as a clearing agent.
-
-=Copper Ammonia= is used as a test for cellulose.
-
-=Ammonical Solution of Potash= is used as a test for fixed oils.
-The solution is a mixture of equal parts of a saturated solution of
-potassium hydroxide and stronger ammonia.
-
-=Oil of Cloves= is used as a clearing fluid for sections preparatory
-to mounting in Canada balsam.
-
-=Canada Balsam= is used as a permanent mounting medium for dehydrated
-specimens, and as a cement for ringing slides.
-
-=Paraffin= is used for general embedding and infiltrating.
-
-=Lugol’s Solution= is used as a test for starch and for aleurone
-grains and proteid matters.
-
-=Osmic Acid=. A two per cent solution is used as a test for fixed
-oils.
-
-=Alcohol, Glycerine, and Water Mixture= is used as a temporary
-mounting medium and as a qualitative test for fixed oils.
-
-=Chlorzinc Iodide= is used as a test for suberin, lignin, cellulose,
-and starch.
-
-=Analine Chloride= is used as a test for lignified cell walls of bast
-fibres and of stone cells.
-
-=Phloroglucin=. A one per cent alcoholic solution is used in
-connection with hydrochloric acid as a test for lignin.
-
-=Hæmatoxylin-Delifields= is used as a test for cellulose.
-
-[Illustration: FIG. 38.--Reagent Set]
-
-
-                             REAGENT SET
-
-Each worker should be provided with a set of =reagent bottles=
-(Fig. 38). Such a set may be selected according to the taste of the
-individual, but experience has shown that a 30 c.c. bottle with a
-ground-in pipette and a rubber bulb is preferable to other types. In
-such forms the pipettes are readily cleaned, and the rubber bulbs can
-be replaced when they become old and brittle. The entire set should
-be protected from dust by keeping it in a case, the cover of which
-should be closed when the set is not in use.
-
-
-                         MEASURING CYLINDER
-
-In order accurately to measure micro-chemical reagents, it is
-necessary to have a standard 50 c.c. cylinder (Fig. 39) graduated to
-c.c.’s. Such a cylinder should form a part of the reagent set.
-
-[Illustration: FIG. 39.--Measuring Cylinder]
-
-
-                           STAINING DISHES
-
-[Illustration: FIG. 40.--Staining Dish]
-
-There is a great variety of =staining dishes= (Fig. 40), but for
-general histological work a glass staining dish with groves for
-holding six or more slides and a glass cover is most desirable.
-
-
-
-
-                             CHAPTER VI
-
-                       HOW TO MOUNT SPECIMENS
-
-
-The method of procedure in mounting specimens for study varies
-according to the nature of the specimen, its preliminary treatment,
-and the character of the mount to be made. As to duration, mounts are
-either temporary or permanent.
-
-
-                          TEMPORARY MOUNTS
-
-In preparing a =temporary mount=, place the specimen in the centre
-of a clean slide and add two or more drops of the temporary mounting
-medium, which may be water, or a mixture of equal parts of alcohol,
-glycerine, and water, or some micro-chemical reagent, as weak Lugol’s
-solution, solution of chloral hydrate, etc. Cover this with a cover
-glass and press down gently. Remove the excess of the mounting
-medium with a piece of blotting paper. Now place the slide on the
-stage and proceed to examine it. Such mounts can of course be used
-only for short periods of study; and when the period of observation
-is finished, the specimen should be removed and the slide washed,
-or the slide washing may be deferred until a number of such slides
-have accumulated. At any rate, when the mounting medium dries, the
-specimen is no longer suitable for observation.
-
-
-                          PERMANENT MOUNTS
-
-Permanent mounts are prepared in much the same way as temporary, but
-of course the mounting medium is different. The kind of permanent
-mounting medium used depends upon the previous treatment of the
-specimen. If the specimen has been preserved in alcohol or glycerine
-and water, it is usually mounted in glycerine jelly. If the specimen
-in question is a powder, it is placed in the centre of the slide and
-a drop or two of glycerine, alcohol, and water mixture added, unless
-the powder was already in suspension in such a mixture. Cut a small
-cube of glycerine jelly and place it in the centre of the powder
-mixture. Lift up the slide by means of pliers, or grasp the two
-edges between the thumb and finger and hold over a small flame of an
-alcohol lamp, or place on a steam-bath until the glycerine jelly has
-melted. Next sterilize a dissecting needle, cool, and mix the powder
-with the glycerine jelly, being careful not to lift the point of the
-needle from the slide during the operation. If the mixing has been
-carefully done, few or no air-bubbles will be present; but if they
-are present, heat the needle, and while it is white hot touch the
-bubbles with its point, and they will disappear. Now take a pair of
-forceps and, after securing a clean cover glass near the edge, pass
-them three times through the flame of the alcohol lamp. While holding
-it in a slanting position, touch one side of the powder mixture and
-slowly lower the cover glass until it comes in complete contact with
-the mixture. Now press gently with the end of the needle-handle, and
-set it aside to cool. When it is cool, place a neatly trimmed label
-on one end of the slide, on which write the name of the specimen,
-the number of the series of which it is to form a part, etc. Any
-excess of glycerine jelly, which may have been pressed out from the
-edges of the cover glass, should not be removed at once, but should
-be allowed to remain on the slide for at least one month in order to
-allow for shrinkage due to evaporation. At the end of a month remove
-the glycerine jelly by first passing the blade of a knife, held in
-a vertical position, the back of the knife being next to the slide,
-around the edge of the cover glass. After turning the knife-blade so
-that the flat side is in contact with slide, remove the jelly outside
-of the cover glass. Any remaining fragments should be removed with
-a piece of old linen or cotton cloth. Finally, ring the edge of the
-cover glass with microscopical cement, of which there are many types
-to be had. If the cleaning has been done thoroughly, there is no
-better ringing cement than Canada balsam.
-
-In mounting cross-sections, the method of procedure is similar to the
-above, with the exception that the glycerine jelly is placed at the
-side of the specimen and not in the centre. While melting the jelly,
-incline the slide in order to allow the melted glycerine jelly to
-flow gradually over the specimen, thus replacing the air contained in
-the cells and intercellular spaces. Finish the mounting as directed
-above, but under no conditions should you stir the glycerine jelly
-with the section.
-
-If specimens, after having been embedded in paraffin or collodion,
-are cut, cleared, stained, and dehydrated, they are usually mounted
-in Canada balsam. A small drop of this substance, which may be
-obtained in collapsible tubes, is placed at one side of the specimen.
-While inclining the slide, gently heat until the Canada balsam covers
-the specimen. Secure a cover glass by the aid of pliers, pass it
-through the flame three times, and lower it slowly while holding it
-in an inclined position. Press gently on the cover glass with the
-needle-handle, and keep in a horizontal position for twenty-four
-hours, then place directly in a slide box or cabinet, since no
-sealing is required.
-
-Glycerine is sometimes used to make permanent mounts, but it is
-unsatisfactory, because the cover glass is easily removed and the
-specimen spoiled or lost, unless ringed--a procedure which is not
-easily accomplished. If the specimen is to be mounted in glycerine,
-it must first be placed in a mixture of alcohol, glycerine, and
-water, and then transferred to glycerine. Lactic acid is another
-permanent liquid-mounting medium, which is unsatisfactory in the same
-way as glycerine, but like glycerine, there are certain special cases
-where it is desirable to use it. When this is used, the slides should
-be kept in a horizontal position, unless ringed.
-
-
-                            COVER GLASSES
-
-Great care should be used In the selection of =cover glasses=,
-however, not only as regards their shape but as to their thickness.
-The standard tube length of the different manufacturers makes an
-allowance of a definite thickness for cover glasses. It is necessary,
-therefore, to use cover glasses made by the manufacturer of the
-microscope in use.
-
-Cover glasses are either square or round. Of each there are four
-different thicknesses and two different sizes. The standard
-thicknesses are: The small size is designated three-fourths and the
-large size seven-eighths.
-
-[Illustration: FIG. 41.--Round Cover Glass]
-
-[Illustration: FIG. 42.--Square Cover Glass]
-
-[Illustration: FIG. 43.--Rectangular Cover Glass]
-
-=Cover glasses= are circular (Fig. 41), square (Fig. 42), or
-rectangular (Fig. 43) pieces of transparent glass used in
-covering the specimens mounted on glass slides. A few years ago
-much difficulty was experienced in obtaining uniformly thick and
-transparent cover glasses, but no such difficulty is experienced
-to-day. The type of cover glass used depends largely upon the
-character of the specimen to be mounted. The square and rectangular
-glasses are selected when a series of specimens are to be mounted,
-but in mounting powdered drugs and histological specimens the round
-cover glasses are preferable because they are more sightly and more
-readily cleaned and rinsed.
-
-
-                            GLASS SLIDES
-
-[Illustration: FIG. 44.--Glass Slide]
-
-=Glass slides= (Fig. 44) are rectangular pieces of transparent glass
-used as a mounting surface for microscopic objects. The slides are
-usually three inches long by one inch wide, and they should be
-composed of white glass, and they should have ground and beveled
-edges. Slides should be of uniform thickness, and they should not
-become cloudy upon standing.
-
-
-                    SLIDE AND COVER-GLASS FORCEPS
-
-Slides and cover glasses should be grasped by their edges. To the
-beginner this is not easy. In order to facilitate holding slides and
-cover glasses during the mounting process, one may use a slide and a
-cover-glass =forceps=. The slide forceps consists of wire bent and
-twisted in such a way that it holds a slide firmly when attached to
-its two edges.
-
-[Illustration: FIG. 45.--Histological Forceps]
-
-[Illustration: FIG. 46.--Forceps]
-
-[Illustration: FIG. 47.--Sliding-pin Forceps]
-
-There are various forms of cover-glass holders, but only two types as
-far as the method of securing the cover glass is concerned. First,
-there are the bacteriological and the histological forceps (Fig. 45),
-which are self-closing. The two blades of such forceps must be forced
-apart by pressure in securing the cover glass. The second type of
-forceps is that in which the two blades are normally separated (Fig.
-46), it being necessary to press the blades to either side of the
-cover glass in order to secure and hold it. There is a modification
-of this type of forceps which enables one to lock the blades by means
-of a sliding pin (Fig. 47), after the cover glass has been secured.
-It is well to accustom oneself to one type, for by so doing one may
-become dexterous in its use.
-
-
-                               NEEDLES
-
-[Illustration: FIG. 48.--Dissecting Needle]
-
-Two =dissecting needles= (Fig. 48) should form a part of the
-histologist’s mounting set. The handles may be of any material, but
-the needle should be of tempered steel and about two inches long.
-
-
-                              SCISSORS
-
-[Illustration: FIG. 49.--Scissors]
-
-Almost any sort of =scissors= (Fig. 49) will do for histology work,
-but a small scissors with fine pointed blades, are preferred.
-Scissors are useful in trimming labels and in cutting strips of
-leaves and sections of fibrous roots that are to be embedded and cut.
-
-
-                              SCALPELS
-
-[Illustration: FIG. 50.--Scalpels]
-
-=Scalpels= (Fig. 50) have steel blades and ebony handles. These vary
-in regard to size and quality of material. The cheaper grades are
-quite as satisfactory, however, as the more expensive ones, and for
-general use a medium-sized blade and handle will be found most useful.
-
-
-                              TURNTABLE
-
-[Illustration: FIG. 51.--Turntable]
-
-Much time and energy may be saved by ringing slides on a =turntable=
-(Fig. 51). There is a flat surface upon which to rest the hand
-holding the brush with cement, and a revolving table upon which the
-slide to be ringed is held by means of two clips. In ringing slides,
-it is only necessary to revolve the table, and at the same time to
-transfer the cement to the edge of the cover glass from the brush
-held in the hand.
-
-
-                              LABELING
-
-There are many ways of =labeling slides=, but the best method is to
-place on the label the name of the specimen, the powder number, and
-the box, the tray or cabinet number. For example:
-
-                       Powdered Arnica Flowers
-                         No. 80--Box A--600.
-
-
-                  PRESERVATION OF MOUNTED SPECIMENS
-
-[Illustration: FIG. 52.--Slide Box]
-
-[Illustration: FIG. 53.--Slide Tray]
-
-Accurately mounted, labeled, and ringed slides should be filed away
-for future study and reference. Such =filing= may be done in slide
-boxes, in slide trays, or in cabinets. Slide boxes are to be had
-of a holding capacity varying from one to one hundred slides. For
-general use, slide boxes (Fig. 52) holding one hundred slides will
-be found most useful. Some workers prefer trays (Fig. 53), because
-of the saving of time in selecting specimens. Trays hold twenty
-slides arranged in two rows. The cover of the tray is divided into
-two sections so that, if desired, only one row of slides is uncovered
-at a time. Slide cabinets (Fig. 54) are particularly desirable for
-storing large individual collections, particularly when the slides
-are used frequently for reference. Large selections of slides should
-be numbered and card indexed in order to facilitate finding.
-
-[Illustration: FIG. 54.--Slide Cabinet]
-
-
-
-
-                               Part II
-
-                  TISSUES CELLS, AND CELL CONTENTS
-
-
-
-
-                              CHAPTER I
-
-                              THE CELL
-
-
-The =cell= is the unit of structure of all plants. In fact the cell
-is the plant in many of the lower forms--so called unicellular
-plants. All plants, then, consist of one or more cells.
-
-While cells vary greatly in size, form, color, contents, and
-function, still in certain respects their structure is identical.
-
-
-                            TYPICAL CELL
-
-The typical vegetable cell is composed of a living portion or
-=protoplast= and an external covering, or =wall=. The protoplast
-includes everything within the wall. It is made up of a number of
-parts, each part performing certain functions yet harmonizing with
-the work of the cell as a whole. The protoplast (protoplasm) is a
-viscid substance resembling the white of an egg. The protoplast, when
-unstained and unmagnified, appears structureless, but when stained
-with dyes and magnified, it is found to be highly organized. The
-two most striking parts of the protoplast are the =cytoplasm= and
-the =nucleus=. The part of the protoplast lining the innermost part
-of the wall is the =ectoplast=, which is less granular and slightly
-denser than most of the =cytoplasm=. The cytoplasm is decidedly
-granular in structure.
-
-In the cytoplasm occurs one or more cavities, =vacuoles=, filled with
-=cell sap=. Embedded in the cytoplasm are numerous =chromatophores=,
-which vary in color in the different cells, from colorless to yellow,
-to red, and to green. The =nucleus= is the seat of the vital activity
-of the cell, and the seat of heredity. The whole life and activity of
-the cell centre, therefore, in and about the nucleus.
-
-The outer portion of the nucleus consists of a thin
-membrane or wall. The membrane encloses numerous granular
-particles--=chromatin=--which are highly susceptible to organic
-stains. Among the granules are thread-like particles or =linin=. Near
-the centre of the nucleus are one or more small rounded nucleoli. The
-liquid portion of the nucleus, filling the membranes and surrounding
-the chromatin, linin, and nucleoli, is the =nuclear sap=.
-
-Other cell contents characteristic of certain cells are crystals,
-starch, aleurone, oil, and alkaloids. The detailed discussion of
-these substances will be deferred until a later chapter.
-
-The =cell wall= which surrounds the protoplast is a product of its
-activity. The structure and composition of the wall of any given cell
-vary according to the ultimate function of the cell. The walls may be
-thin or thick, porous or non-porous, and colored or colorless. The
-composition of cell walls varies greatly. The majority of cell walls
-are composed of cellulose, in other cells of linin, in others of
-cutin, and in still others of suberin, etc. In the majority of cells
-the walls are laid down in a series of layers one over the other by
-apposition, similar to the manner of building a pile of paper from
-separate sheets. The first layer is deposited over the primary wall,
-formed during cell division; to this is added another layer, etc. A
-modification of this manner of growth is that in which the layers are
-built up one over the other, but the building is gradually done by
-the deposit of minute particles of cell-wall substance over the older
-deposits. Such walls are never striated, as is likely to be the case
-in cell walls formed by the first method. In other cells the walls
-are increased in thickness by the deposition of new wall material in
-the older membrane. The cell walls will be discussed more fully when
-the different tissues are studied in detail.
-
-
-                INDIRECT CELL DIVISION (KARYOKINESIS)
-
-The purpose of cell division is to increase the number of cells
-of a tissue, an organ, an organism, or to increase the number of
-organisms, etc. Such cell divisions involve, first, an equal division
-of the protoplast and, secondly, the formation of a wall between
-the divided protoplasts. The first changes in structure of a cell
-undergoing division occur in the nucleus.
-
-
-                CHANGES IN A CELL UNDERGOING DIVISION
-
-The =linin threads= become thicker and shorter. The =chromatin
-granules= increase in size and amount; the threads and chromatin
-granules separate into a definite number of segments or =chromosomes=
-(Plate 1, Fig. 2). The nuclear membrane becomes invested with a
-fibrous protoplasmic layer which later separates and passes into
-either end of the cell, there forming the =polar caps= (Plate 1, Fig.
-3).
-
-The =nuclear membrane= and the =nucleoli= disappear at about this
-time. Two fibres, one from each polar cap, become attached to
-opposite sides of the individual chromosomes. Other fibres from
-the two polar caps unite to form the =spindle fibres=, which thus
-extend from pole to pole. All these spindle fibres form the =nuclear
-spindle= (Plate 1, Fig. 5).
-
-The chromosomes now pass toward the division centre of the cell or
-=equatorial plane= and form, collectively, the =equatorial plate=
-(Plate 1, Fig. 5). At this point of cell division, the chromosomes
-are =U=-shaped, and the curved part of the chromosomes faces the
-equatorial plane. The chromosomes finally split into two equal
-parts (Plate 1, Fig. 6). The actual separation of the halves of
-chromosomes is brought about by the attached polar fibres, which
-contract toward the polar caps (Plate 1, Fig. 7). The chromosomes are
-finally drawn to the polar caps (Plate 1, Fig. 8). The chromosomes
-now form a rounded mass. They then separate into linin threads
-and chromatin granules. Nucleoli reappear, and nuclear sap forms.
-Finally, a nuclear membrane develops. The spindle fibres, which still
-extend from pole to pole, become thickened at the equatorial plane
-(Plate 1, Fig. 8), and finally their edges become united to form the
-=cell-plate= (Plate 1, Fig. 9), which extends across the cell, thus
-completely separating the mother cell into two daughter cells. After
-the formation of the cell-plate, the spindle fibres disappear. The
-cell becomes modified to form the =middle lamella=, on either side of
-which the daughter protoplast adds a cellulose layer. The ultimate
-composition of the middle lamella and the composition and structure
-of the cell wall will differ according to the function which the cell
-will finally perform.
-
-[Illustration: PLATE 1
-
-  Nine figures, showing stages in the cell-division common to the
-  onion root (_Allium cepa_, L.)]
-
-
-                   ORIGIN OF MULTICELLULAR PLANTS
-
-All multicellular plants are built up by the repeated cell division
-of one original cell. If the cells formed are similar in structure
-and function, they form a tissue. In multicellular plants many
-different kinds of tissues will be formed as a result of cell
-division, since there are many different functions to be performed by
-such an organism. When several of these tissues become associated and
-their functions are correlated, they form an organ. The association
-of several organs in one form makes an organism. The oak-tree is an
-organism. It is made up of organs known as flowers, leaves, stems,
-roots, etc. Each of these organs is in turn made up of several kinds
-of tissue. In some cases it is difficult to designate a single
-function to an aggregation of cells (tissue). In fact, a tissue may
-perform different functions at different periods of its existence
-or it may perform two functions at one and the same time; as an
-example, stone cells, whose primary function is mechanical, in many
-cases function as storage tissue. The cells forming the tissues of
-the plant, in fact, show great adaptability in regard to the function
-which they perform. Nevertheless there is a predominating function
-which all tissues perform, and the structure of the cells forming
-such tissues is so uniform that it is possible to classify them.
-
-The functional classification of tissues is chosen for the purpose
-of demonstrating the adaptation of cell structure to cell function.
-If the cells performing a similar function in the different plants
-were identical in number, distribution, form, color, size, structure,
-and cell contents, there would not be a science of histology upon
-which the art of microscopic pharmacognosy is based. It may be said,
-however, with certainty, that the cells forming certain of the
-tissues of any given species of plant will differ in a recognizable
-degree from cells performing a similar function in other species of
-plants. Often a tissue is present in one plant but absent in another.
-For example, many aquatic plants are devoid of mechanical fibrous
-cells. The barks of certain plants have characteristic stone cells,
-while in many other barks no stone cells occur. Many leaves have
-characteristic trichomes; others are free from trichomes, etc. Yet
-all cells performing a given function will structurally resemble
-each other. In the present work the nucleus and other parts of the
-living protoplast will not be considered, for the reason that these
-parts are not in a condition suitable for study, because most drugs
-come to market in a dried condition, a condition which eliminates
-the possibility of studying the protoplast. The general structure of
-the cells forming the different tissues will first be considered,
-then their variation, as seen in different plants, and finally their
-functions.
-
-
-
-
-                             CHAPTER II
-
-                     THE EPIDERMIS AND PERIDERM
-
-
-The epidermis and its modifications, the hypodermis and the periderm,
-form the dermal or protective outer layer or layers of the plant.
-
-The epidermis of most leaves, stems of herbs, seeds, fruits, floral
-organs, and young woody stems consists of a single layer of cells
-which form an impervious outer covering, with the exception of the
-stoma.
-
-
-                           LEAF EPIDERMIS
-
-The cells of the =epidermis= vary in size, in thickness of the side
-and end walls, in form, in arrangement, in character of outgrowths,
-in the nature of the surface deposits, in the character of
-wall--whether smooth or rough--and in size.
-
-In cross-sections of the leaf the character of both the side and end
-walls is easily studied.
-
-In surface sections--the view most frequently seen in powders--the
-side walls are more conspicuous than the end wall (Plates 2 and 3).
-This is so because the light is considerably retarded in passing
-through the entire length of the side walls, while the light is
-retarded only slightly in passing through the end wall. The light in
-this case passes through the width (thickness) of the wall only. The
-outer walls of epidermal cells are characteristic only when they are
-striated, rough, pitted, colored, etc. In the majority of leaves the
-outer wall of the epidermal cells is not diagnostic in powders, or in
-surface sections.
-
-The thickness of the end and side walls of epidermal cells differs
-greatly in different plants.
-
-As a rule, leaves of aquatic and shade-loving plants, as well as the
-leaves of most herbs have thinner walled epidermal cells than have
-the leaves of plants growing in soil under normal conditions, or than
-have the leaves of shrubs and trees.
-
-[Illustration: PLATE 2
-
-                           LEAF EPIDERMIS
-
-  1. Uva-ursi (_Arctostaphylos uva-ursi_, [L.] Spring).
-  2. Boldus (_Peumus boldus_, Molina).
-  3. Catnip (_Nepeta cataria_, L.).
-  4. Digitalis (_Digitalis purpurea_, L.).
-  4-A. Origin of hair.]
-
-[Illustration: PLATE 3
-
-                           LEAF EPIDERMIS
-
-  1. Upper striated epidermis of chirata leaf (_Swertia chirata_,
-  [Roxb.] Ham.).
-  2. Green hellebore leaf (_Veratrum viride_, Ait.).
-  3. Boldus leaf (_Peumus boldus_, Molina).
-  4. Under epidermis of India senna (_Cassia angustifolia_, Vahl.).]
-
-The widest possible range of cell-wall thickness is therefore found
-in the medicinal leaves, because the medicinal leaves are collected
-from aquatic plants, herbs, shrubs, trees, etc.
-
-The outer wall is always thicker than the side walls. Even the
-side walls vary in thickness in some leaves, the wall next to the
-epidermis being thicker than the lower or innermost portion of the
-wall. Frequently the outermost part of the side walls is unequally
-thickened. This is the case in the beaded side walls characteristic
-of the epidermis of the leaves of laurus, myrcia, boldus, and
-capsicum seed, etc. The thickness of the side walls of the epidermal
-cells of most leaves varies in the different leaves.
-
-In most leaves there are five typical forms of arrangement of
-epidermal cells: First, those over the veins which are elongated
-in the direction of the length of the leaf; and, secondly, those
-on other parts of the leaf which are usually several-sided and not
-elongated in any one direction. If the epidermis of the leaf has
-stoma, then there is a third type of arrangement of the epidermal
-cells around the stoma; fourthly, the cells surrounding the base of
-hairs; and fifthly, outgrowths of the epidermis, non-glandular and
-glandular hairs, etc.
-
-It should be borne in mind that in each species of plant the five
-types of arrangement are characteristic for the species.
-
-The character of the outer wall of the epidermal cells differs
-greatly in different plants. In most cases the wall is smooth; senna
-is an example of such leaves. In certain other leaves the wall
-is rough, the roughness being in the form of striations. In some
-cases the striations occur in a regular manner; belladonna leaf is
-typical of such leaves. In other instances the wall is striated in
-an irregular manner as shown in chirata epidermis. Very often an
-epidermis is rough, but the roughness is not due to striations.
-In these cases the epidermis is unevenly thickened, the thin
-places appearing as slight depressions, the thick places as slight
-elevations. Boldus has a rough, but not a striated surface.
-
-=Surface deposits= are not of common occurrence in medicinal plants;
-waxy deposits occur on the stem of sumac, on a species of raspberry,
-on the fruit of bayberry, etc. Resinous deposits occur on the leaves
-and stems of grindelia species, and on yerba santa.
-
-In certain leaves there are two or three layers of cells beneath the
-epidermis that are similar in structure to the epidermal cells. These
-are called hypodermal cells, and they function in the same way as the
-epidermal cells.
-
-Hypodermal cells are very likely to occur on the margin of the leaf.
-Uva-ursi leaf has a structure typical of leaves with hypodermal
-marginal cells. Uva-ursi, like other leaves with hypodermal cells has
-a greater number of hypodermal cells at the leaf margin than at any
-other part of the leaf surface.
-
-The cutinized walls of epidermal cells are stained red with saffranin.
-
-
-                           TESTA EPIDERMIS
-
-=Testa epidermal cells= form the epidermal layers of such seeds as
-lobelia, henbane, capsicum, paprika, larkspur, belladonna, scopola,
-etc.
-
-In surface view the end walls are thick and wavy in outline;
-frequently the line of union--middle lamella--of two cells is
-indicated by a dark or light line, while in others the wall between
-two cells appears as a single wall. The walls are porous or
-non-porous, and the color of the wall varies from yellow to brown, to
-colorless. These cells always occur in masses, composed partially of
-entire and partially of broken fragments.
-
-In lobelia seed (Plate 4, Fig. 2) the line of union of adjacent cell
-walls appears as a dark line. The walls are wavy in outline, of a
-yellowish-red color and not porous.
-
-In henbane seed (Plate 4, Fig. 3) the line of union between the cells
-is scarcely visible; the walls are decidedly wavy, more so than in
-lobelia, and no pits are visible.
-
-In capsicum seed (Plate 4, Fig. 1) the cells are very wavy and
-decidedly porous, the line of union between the cell walls being
-marked with irregular spaces and lines.
-
-In belladonna seed (Plate 5, Fig. 1) the walls between two adjacent
-cells are non-striated and non-porous, and extremely irregular in
-outline.
-
-[Illustration: PLATE 4
-
-                        TESTA EPIDERMAL CELLS
-
-  1. Capsicum seed (_Capsicum frutescens_, L.).
-  2. Lobelia seed (_Lobelia inflata_, L.).
-  3. Henbane seed (_Hyoscyamus niger_, L.).]
-
-[Illustration: PLATE 5
-
-                             TESTA CELLS
-
-  1. Belladonna seed (_Atropa belladonna_, L.).
-  2. Star-aniseed (_Illicium verum_, Hooker).
-  3. Stramonium seed (_Datura stramonium_, L.).]
-
-In star-anise seed (Plate 5, Fig. 2) the walls are irregularly
-thickened and wavy in outline.
-
-In stramonium seed (Plate 5, Fig. 3) the walls are very thick, wavy
-in outline, and striated.
-
-
-                       PLANT HAIRS (TRICHOMES)
-
-In histological work plant hairs are of great importance, as they
-offer a ready means of distinguishing and differentiating between
-plants, or parts of plants, when they occur in a broken or finely
-powdered condition. There is no other element in powdered drugs which
-is of so great a diagnostic value as the plant hair. The same plant
-will always have the same type of hair, the only noticeable variation
-being in the size. In microscopical drug analysis the presence of
-hairs is always noted, and in many cases the purity of the powder
-can be ascertained from the hairs. Botanists seem to have given
-little attention to the study of plant hairs. This accounts for the
-fact that information concerning them is very meagre in botanical
-literature, and, as far as the author can learn, no one has attempted
-to classify them. In systematic work, plant hairs could be used to
-great advantage in separating genera and even species. Hairs are,
-of course, a factor now in systematic work. The lack of hairs is
-indicated by the term glabrous. Their presence is indicated by such
-terms as hispid, villous, etc. In certain cases the term indicates
-position of the hair as ciliate when the hair is marginal. When hairs
-influence the color of the leaf, such terms as cinerous and canescent
-are used. In all the cases cited no mention is made of the real
-nature of the hair.
-
-In systematic work, as in pharmacognosy, we must work with dried
-material, and it is only those hairs which retain their form under
-such conditions which are of classification value.
-
-Hairs are the most common outgrowths of the epidermal cells. They
-are classified as glandular or non-glandular, according to their
-structure and function. The glandular hairs will be considered under
-synthetic tissue.
-
-Each group is again subdivided into a number of secondary groups,
-depending upon the number of cells present, their form, their
-arrangement, their size, their color, the character of their walls,
-whether rough or smooth, whether branched or non-branched, whether
-curved, twisted, straight, or twisted and straight, whether pointed,
-blunt, or forked.
-
-
-                           FORMS OF HAIRS
-
-                               PAPILLÆ
-
-=Papillæ= are epidermal cells which are extended outward in the form
-of small tubular outgrowths.
-
-Papillæ occur on the following parts of the plant: flower-petals,
-stigmas, styles, leaves, stems, seeds, and fruits. Papillæ occur on
-only a few of the medicinal leaves.
-
-The under surface of both Truxillo (Plate 6, Fig. 3) and Huanuca coca
-have very small papillæ. The outermost wall of these papillæ are much
-thicker than the side walls. The papillæ of klip buchu (Plate 6, Fig.
-4), an adulterant of true buchu, has large thick-walled papillæ.
-
-The velvety appearance of most flower-petals (Plate 6, Figs. 2 and
-5) is due to the presence of papillæ. The papillæ of flower-petals
-are very variable. In calendula flowers (Plate 6, Fig. 1) they
-are small, yellowish in color, and the outer wall is marked with
-parallel striations which appear as small teeth in cross-section.
-The ray petal papillæ of anthemis consist of rather large, broad,
-blunt papillæ with slightly striated walls. The papillæ of the ray
-petals of the white daisy consist of papillæ which have medium sized,
-cone-shaped papillæ with finely striated walls. The papillæ of the
-flower stigma vary greatly in different flowers. In some cases two or
-more types of papillæ occur, but even in these cases the papillæ are
-characteristic of the species.
-
-The papillæ differ greatly in the case of the flowers of the
-compositæ, where two types of flowers are normally present--namely,
-the ray flowers and the disk flowers.
-
-In all cases observed the papillæ of the stigma of the ray flowers
-are always smaller than the papillæ of the stigma of the disk
-flowers. It would appear from extended observation that the papillæ
-of the ray flower stigma are being gradually aborted. The papillæ of
-the style are always different from the papillæ of the stigma. The
-style papillæ are always smaller, and they are of a different form.
-
-[Illustration: PLATE 6
-
-                               PAPILLÆ
-
-  1. Calendula flowers (_Calendula officinalis_, L.).
-  2. White daisy ray flower (_Chrysanthemum leucanthemum_, L.).
-  3. Coca leaf (_Erythroxylon coca_, Lamarck).
-  4. Klip buchu.
-  5. Anthemis ray petal (_Anthemis nobilis_, L.).]
-
-
-                   UNICELLULAR NON-GLANDULAR HAIRS
-
-=True plant hairs= are tubular outgrowths of the epidermal cell, the
-length of these outgrowths being several times the width of the hair.
-
-The unicellular hairs are common to many plants. The two groups
-of non-glandular unicellular hairs are, first, the solitary; and
-secondly, the clustered hairs.
-
-=Solitary unicellular hairs= occur on the leaves of chestnut, yerba
-santa, lobelia, cannabis indica, the fruit of anise, and the stem of
-allspice, senna, and cowage.
-
-Chestnut hairs (Plate 7, Fig. 1) have smooth yellowish-colored walls,
-and the cell cavity contains reddish-brown tannin. These hairs occur
-solitary or clustered; the clustered hairs normally occur on the
-leaf, but in powdering the drug, individual hairs of the cluster
-become separated or solitary.
-
-Yerba santa hairs (Plate 7, Fig. 4) are twisted, the lumen or cell
-cavity is very small, and the walls, which are very thick, are
-grayish-white.
-
-Lobelia hairs (Plate 7, Fig. 5) are very large. The walls are
-grayish-white, and the outer surface extends in the form of small
-elevations which make the hair very rough. The hair tapers gradually
-to a solid point.
-
-Cannabis indica hairs (Plate 7, Fig. 6) are curved. The apex tapers
-to a point and the base is broad, and it frequently contains deposits
-of calcium carbonate. The walls are grayish-white in appearance, and
-rough. The roughness increases toward the apex.
-
-The hairs of anise (Plate 7, Fig. 7) are mostly curved; the walls are
-thick, yellowish-white, and the outer surface is rough; this is due
-to the numerous slight centrifugal projections of the outer wall.
-
-Allspice stem hairs (Plate 7, Fig. 2) have smooth walls. The cell
-cavity is reddish-brown. The hair is curved.
-
-The hair of senna (Plate 7, Fig. 10) is light greenish-yellow with
-rough papillose walls. The hair is usually curved and tapering, and
-it does not have any characteristic cell contents.
-
-[Illustration: PLATE 7
-
-                     UNICELLULAR SOLITARY HAIRS
-
-  1. Chestnut leaf (_Castanea dentata_, [Marsh] Borkh).
-  2. Allspice stems (_Pimento, officinalis_, Lindl.).
-  3. Cowage.
-  4. Yerba santa (_Eriodictyon californicum_, [H. and A.] Greene).
-  5. Lobelia (_Lobelia inflata_, L.).
-  6. Cannabis indica (_Cannabis saliva_, L.).
-  7. Anise fruit (_Pimpinella anisum_, L.).
-  8. Hesperis matronalis (_Hesperis matronalis_, L.).
-  9. Galphimia glauca (_Galphimia glauca_, Cav.).
-  10. Senna (_Cassia angustifolia_, Vahl.).]
-
-[Illustration: PLATE 8
-
-                     CLUSTERED UNICELLULAR HAIRS
-
-  1. and 2. European oak (_Quercus infectoria_, Olivier).
-  3. Kamala (_Mallotus philippinensis_, [Lam.] [Muell.] Arg.).
-  4. Witch-hazel leaf (_Hamamelis virginiana_, L.).
-  5. Althea leaf (_Althæa officinalis_, L.).]
-
-Cowage hairs (Plate 7, Fig. 3) are lance-shaped, and they
-terminate in a sharp point. The outer wall contains numerous
-recurved teeth-like projections. The cell cavity is filled with a
-reddish-brown contents which are somewhat fissured.
-
-=Clustered unicellular hairs= occur on the leaves of chestnut,
-witch-hazel, althea, European oak, etc. In European oak (Plate 8,
-Figs. 1 and 2) clusters of two and three hairs occur. The walls are
-yellowish-white, smooth, and the tip of the hair is solid.
-
-In kamala (Plate 8, Fig. 3) clusters of seven or more hairs occur;
-the walls are yellowish, and the cell cavity is reddish-brown. In
-witch-hazel leaf (Plate 8, Fig. 4) clusters of a variable number
-of hairs occur. The hairs, which are of various lengths, have
-yellowish-white, thick, smooth walls, and reddish cell contents.
-
-In althea leaf (Plate 8, Fig. 5) the hairs are nearly straight and
-the walls are smooth. The basal portions of the hair are strongly
-pitted.
-
-=Branched solitary unicellular hairs= occur on the leaves of hesperis
-matronalis (Plate 7, Fig. 8), and on galphimia glauca (Plate 7, Fig.
-9).
-
-The hair of hesperis matronalis has smooth walls, and the two
-branches grow out nearly parallel to the leaf surface.
-
-The hair of galphimia glauca has rough walls, and the two branches
-grow upward in a bifurcating manner.
-
-
-                         MULTICELLULAR HAIRS
-
-=Multicellular= hairs are divided into the uniseriate and the
-multiseriate hairs. Both of these groups are divided into the
-branched and the non-branched hairs, as follows:
-
-  1. =Uniseriate=.
-      (_A_) =Non-branched.=
-      (_B_) =Branched.=
-
-  2. =Multiseriate.=
-      (_A_) =Non-branched.=
-      (_B_) =Branched.=
-
-=Multicellular uniseriate non-branched hairs= occur on the leaves of
-digitalis, Western and Eastern skullcap, peppermint, thyme, yarrow,
-arnica flowers, and sumac fruit.
-
-[Illustration: PLATE 9
-
-             MULTICELLULAR UNISERIATE NON-BRANCHED HAIRS
-
-  1. Digitalis leaf (_Digitalis purpurea_, L.).
-  2. Arnica flower (_Arnica montana_, L.).
-  3. Western skullcap plant (_Scutellaria canescens_, Nutt.).
-  4. Eastern skullcap plant (_Scutellaria lateriflora_, L.).
-  5. Peppermint leaf (_Mentha piperita_, L.).
-  6. Thyme leaf (_Thymus vulgaris_, L.).
-  7. Yarrow flowers (_Achillea millefolium_, L.).
-  8. Wormwood leaf (_Artemisia absinthium_, L.).
-  9. Sumac fruit (_Rhus glabra_, L.).]
-
-Digitalis hairs (Plate 9, Fig. 1) are made up of a varying number of
-uniseriate-arranged cells of unequal length, frequently placed at
-right angles to the cells above and below; the walls are of a whitish
-color, and are rough or smooth.
-
-Eastern skullcap (Plate 9, Fig. 4) has hairs with not more than four
-cells; these hairs are curved, and the walls are whitish, sometimes
-smooth, but usually rough. In Western skullcap (Plate 9, Fig. 3) the
-hairs have sometimes as many as seven cells. The walls are white and
-rough, and the individual cells of the hair are much larger than are
-the cells of the hairs of true skullcap.
-
-Peppermint (Plate 9, Fig. 5) has from one to eight cells. The hair is
-curved, and the walls are very rough.
-
-Thyme (Plate 9, Fig. 6) has short, thick, rough-walled trichomes, the
-terminal cell usually being bent at nearly right angles to the other
-cells.
-
-Yarrow hairs (Plate 9, Fig. 7) have a variable number of cells. In
-all the hairs the basal cells are short and broad, while the terminal
-cell is greatly elongated.
-
-Arnica hairs (one form, Plate 9, Fig. 2) have frequently as many as
-four cells, the terminal cell being longer than the basal cells. The
-walls are white and smooth.
-
-Sumac-fruit hairs (Plate 9, Fig. 9) have spindle-shaped,
-reddish-colored hairs.
-
-=Multicellular multiseriate non-branched hairs= occur on cumin fruit
-and on the tubular part of the corolla of calendula.
-
-The hairs on cumin fruit vary considerably in size. All the hairs
-are spreading at the base and blunt or rounded at the apex. The
-cells forming the hair are narrow and the walls are thick. Three
-differently sized hairs are shown in Plate 10, Fig. 1.
-
-The hairs of the base of the ligulate petals of calendula (Plate 10,
-Fig. 2) are biseriate. The hairs are very long and the walls are very
-thin.
-
-=Multicellular uniseriate branched hairs= occur on the leaves of
-dittany of Crete, mullen, and on the calyx of lavender flowers.
-
-The dittany of Crete (Plate 11, Fig. 3) hair is smooth-walled, and
-the branches are alternate.
-
-In mullen (Plate 11, Fig. 1) the hairs have whorled branches, the
-walls are smooth, and the cell cavity usually contains air.
-
-[Illustration: PLATE 10
-
-            MULTICELLULAR MULTISERIATE NON-BRANCHED HAIRS
-
-  1. Cumin (_Cuminum cyminum_, L.).
-  2. Marigold (_Calendula officinalis_, L.).]
-
-[Illustration: PLATE 11
-
-               MULTICELLULAR UNISERIATE BRANCHED HAIRS
-
-  1. Mullen leaf (_Verbascum thapsus_, L.).
-  2. Lavender flowers (_Lavandula vera_, D. C.).
-  3. Dittany of Crete (_Origanum dictamnus_, L.).]
-
-The lavender hairs (Plate 11, Fig. 2) have mostly opposite branches,
-and the walls are rough. Thus the multicellular branched hairs may be
-divided into subgroups which have alternate, opposite, whorled, or in
-certain hairs irregularly arranged branches. Each class may be again
-subdivided according to color, character of cell termination, etc.,
-as cited at the beginning of the chapter.
-
-Occasionally multicellular hairs assume the form of a shield (Plate
-12, Fig. 1); in such cases the hair is termed peltate, as in the
-non-glandular multicellular hair of shepherdia canadensis.
-
-Hairs grow out from the surface of the epidermis in a perpendicular,
-a parallel, or in an oblique direction. Hairs which grow parallel or
-oblique to the surface are usually curved, and the outer curved part
-of the wall is usually thicker than the inner curved wall.
-
-The mature hairs of some plants consist of dead cells. In other
-plants the cells forming the hair are living. When dried, those
-hairs, which were dead before drying, contain air; while those hairs
-which were living before drying, show great variation in color and in
-the nature of the cell contents. The contents are either organic or
-inorganic. The commonest organic constituent is dried protoplasm. In
-cannabis indica are deposits of calcium carbonate.
-
-=Multicellular multiseriate branched hairs= are the ultimate division
-of the pappus of erigeron, aromatic goldenrod, arnica, grindelia,
-boneset, and life-everlasting.
-
-The hairs of erigeron (Plate 13, Figs. 1 and 2) are slender; the
-walls are porous. Each hair terminates in two cells, which are
-greatly extended and sharp-pointed; the branches from the basal part
-of the hairs (Plate 13, Fig. 1) are of about the same length as the
-apical branches.
-
-The hairs of aromatic goldenrod (Plate 13, Figs. 3 and 4) are larger
-than those of erigeron; the diameter is greater and the walls are
-non-porous. The apex of the hair terminates in a group of about four
-cells of unequal length, which are sharp-pointed. The branches of the
-basal cells (Plate 13, Fig. 3) are similar to the branches of the
-apical cells.
-
-The hairs of arnica (Plate 14, Figs. 1 and 2) have thick, strongly
-porous walls; the branches terminate in sharp points. The apex of the
-hair terminates in a single cell. The basal branches (Plate 14, Fig.
-2) are much longer than special branches.
-
-[Illustration: PLATE 12
-
-                  NON-GLANDULAR MULTICELLULAR HAIRS
-                _Shepherdia canadensis_, [L.] Nutt.]
-
-[Illustration: PLATE 13
-
-              MULTICELLULAR MULTISERIATE BRANCHED HAIRS
-
-  1. Basal hairs of erigeron (_Erigeron canadensis_, L.).
-  2. Apical hairs of erigeron (_Erigeron canadensis_, L.).
-  3. Basal hairs of aromatic goldenrod (_Solidago odora_, Ait.).
-  4. Apical hairs of aromatic goldenrod (_Solidago odora_, Ait.).]
-
-The hair of grindelia (Plate 14, Figs. 3 and 4) has very thick walls
-with numerous elongated pores. The apex of the hair terminates in
-a cluster of cells with short, free, sharp-pointed ends. The basal
-branches (Plate 14, Fig. 4) are longer than the apical branches.
-
-Boneset hair (Plate 15, Figs. 1 and 2) has non-porous walls. The
-apex of the hair terminates in two blunt-pointed cells. The terminal
-wall is thicker than the side wall. Some of the branches lower
-down terminate in cells with very thick or solid points. The basal
-branches (Plate 15, Fig. 1) are longer, but the cells are narrower
-and more strongly tapering than are the branches of the apical part
-of the hair.
-
-Life-everlasting (Plate 15, Figs. 3 and 4) has uniformly thickened
-but non-porous walls. The hair terminates in two blunt-pointed,
-greatly elongated cells.
-
-The basal branches (Plate 15, Fig. 4) are narrower, slightly
-tapering, and the base of the branches frequently curve downward.
-
-The cell cavities of these hairs are filled with air.
-
-The walls of hairs are composed of cutin, of lignin, and of cellulose.
-
-
-                              PERIDERM
-
-The =periderm= is the outer protective covering of the stems
-and roots of mature shrubs and trees. The periderm replaces the
-epidermis. The periderm may be composed of cork cells, stone
-cell-cork, or a mixture of cork, parenchyma, fibres, stone cells, etc.
-
-
-                            CORK PERIDERM
-
-The typical periderm is made up of =cork cells=. Cork cells vary in
-appearance, according to the part of the cell viewed.
-
-[Illustration: PLATE 14
-
-              MULTICELLULAR MULTISERIATE BRANCHED HAIRS
-
-  1. Apical hairs arnica (_Arnica montana_, L.).
-  2. Basal hairs arnica (_Arnica montana_, L.).
-  3. Apical hairs grindelia (_Grindelia squarrosa_, [Pursh] Dunal).
-  4. Basal hairs grindelia (_Grindelia squarrosa_, [Pursh] Dunal).]
-
-[Illustration: PLATE 15
-
-              MULTICELLULAR MULTISERIATE BRANCHED HAIRS
-
-  1. Apical hairs boneset (_Eupatorium perfoliatum_, L.).
-  2. Basal hairs boneset (_Eupatorium perfoliatum_, L.).
-  3. Apical hairs life-everlasting (_Gnaphalium obtusifolium_, L.).
-  4. Basal hairs life-everlasting (_Gnaphalium obtusifolium_, L.).]
-
-On surface view (Plate 16, Fig. A) the cork cells are angled in
-outline and are made up of from four to seven side walls; five-
-and six-sided cells are more common than the four-and seven-sided
-cells. Surface sections of cork cells show their length and width.
-These side walls usually appear nearly white, while the end wall,
-particularly of the outermost cork cells, usually appears brown or
-reddish-brown, or in some cases nearly black.
-
-Cork cells on cross-section are rectangular in form, and they are
-arranged in superimposed rows, the number of rows being gradually
-increased as the plant grows older. Such an increase in the number of
-rows of cork cells is shown in the cross-section of cascara sagrada
-(Plate 16, Fig. C).
-
-Cork cells fit together so closely that there is no intercellular
-spaces between the cells. In this case two rows of cork cells occupy
-no greater space than the solitary row of cork cells immediately over
-and external to them. As a rule, the outermost layers of cork cells
-have a narrower radial diameter than the cork cells of the underlying
-layers. This is due to the fact that these outer cells are stretched
-as the stem increases in diameter. This view shows the height of
-cork cells, but not always the length, which will, of course, vary
-according to the part of the cell cut across. In a section a few
-millimeters in diameter, however, all the variations in size may be
-observed. The color of the walls is nearly white.
-
-The cavity may contain tannin or other substances. When tannin is
-present, the cavity is of a brownish or brownish-red color, or it may
-be nearly black. Most barks appear devoid of any colored or colorless
-cell contents.
-
-The radial section (Plate 16, Fig. B) of cork cells shows the height
-of the cells and the width of the cells at the point cut across. Some
-cells will be cut across their longest diameter, while others will
-be cut across their shortest diameter. Cork cells are, therefore,
-smaller in radial section than they are in cross-section. The color
-of the walls is white, and the color and nature of the cell contents
-vary for the same reasons that they vary in cross-sections.
-
-The number of layers of cork cells occurring in cross- and
-radial-sections varies according to the age of the plant, to the type
-of plant, and to the conditions under which the plant is growing.
-
-The number of layers of cork cells is not of diagnostic importance,
-nor is the surface view of cork cells diagnostic except in certain
-isolated cases.
-
-[Illustration: PLATE 16
-
-       PERIDERM OF CASCARA SAGRADA (_Rhamnus purshiana_, D.C.)
-
-  _A._ 1, Outline of cork cells; 2, Line of contact of adjoining cork
-  cells.
-
-  _B._ Radial longitudinal section of cascara sagrada. 1, Cork cells;
-  2, Phellogen; 3, Forming parenchyma cells; 4, Cortical parenchyma
-  cells.
-
-  _C._ Cross-section of cascara sagrada. 1, Cork cells; 2, Phellogen;
-  3, Forming parenchyma cells; 4, Cortical parenchyma cells.]
-
-The presence or absence of cork or epidermal tissue in powders must
-always be noted. The presence of cork enables one to distinguish
-Spanish from Russian licorice. In like manner, the presence of
-epidermis enables one to distinguish the pharmacopœial from the
-unofficial peeled calamus. The absence of epidermis in Jamaica ginger
-is one of the means by which this variety is distinguished from the
-other varieties of ginger, etc.
-
-In canella alba the periderm is replaced by stone cell-cork. That is,
-the cells forming the periderm are of a typical cork shape, but the
-walls are lignified, unequally thickened, and the inner or thicker
-walls are strongly porous, and the walls are of a yellowish color.
-Stone cell-cork forms the periderm of clove bark also, but the cells
-are narrower and longer, and the inner wall is not so thick or porous
-as is the case in canella alba bark.
-
-
-                         STONE CELL PERIDERM
-
-In canella alba (Plate 17, Fig. B) cork periderm is frequently
-replaced by stone cells, particularly in the older barks. These stone
-cells form the periderm because they replace the cork periderm, which
-fissures and scales off as the root increases in diameter.
-
-The side and end walls of cork cells are of nearly uniform diameter.
-Exceptions occur, but they are not common. In buchu stem (Plate
-101, Fig. 3), the cork cells have thick outer walls, but thin sides
-and inner walls. The cell cavity contains reddish-brown deposits of
-tannin.
-
-
-                 PARENCHYMA AND STONE CELL PERIDERM
-
-As the trees and shrubs increase in diameter, cracks or fissures
-occur in the periderm, or corky layer. In such cases the phellogen
-cells divide and redivide in such manner as to cut off a portion of
-the parenchyma cells, stone cells, and fibres of the cortex which
-is inside of and below the fissure. All the parenchyma cells, etc.,
-exterior to the newly formed cork cells soon lose their living-cell
-contents, since their food-supply is cut off by the impervious walls
-of the cork cells. In time they are forced outward by the developing
-cork cells until they partially or completely fill the break in the
-periderm. In white oak bark (Plate 18), as in other barks, a large
-part of the periderm is composed of dead and discolored cortical
-cells.
-
-[Illustration: PLATE 17
-
-  _A._ Cross-section of Mandrake Rhizome (_Podophyllum peltatum_, L.).
-       1. Epidermis.
-       2. Phellogen.
-       3. Cortical parenchyma.
-  _B._ Stone cell periderm of white cinnamon (_Canella alba_, Murr.).]
-
-[Illustration: PLATE 18
-
-             PERIDERM OF WHITE OAK (_Quercus alba_, L.)
-
-  1. Outer layer of cork cells. 2. Cortical parenchyma cells. 3.
-  Stone cells. 4. Phellogen. 5. Cortical parenchyma cells.]
-
-
-                        ORIGIN OF CORK CELLS
-
-The cork cells are formed by the meristimatic phellogen cells, which
-originate from cortical parenchyma. These cells divide into two
-cells, the outer changing into a cork cell, while the inner cell
-remains meristimatic. In other instances the outer cell remains
-meristimatic, while the inner cell changes into a cortical parenchyma
-cell. The development of a cortical parenchyma cell from a divided
-phellogen cell is shown in Plate 101, Fig. 6. Both the primary and
-secondary cork cells originate from the phellogen or cork cambrium
-layer. Cork cells do not contain living-cell contents; in fact, in
-the majority of medicinal barks the cork cells contain only air.
-
-The walls of typical cork cells are composed, at least in part, of
-suberin, a substance which is impervious to water and gases. In
-certain cases layers of cellulose, lignin, and suberin have been
-identified. Suberin, however, is present in all cork cells, and in
-some cases all of the walls of cork cells are composed of suberin.
-
-Suberized cork cells are colored yellow with strong sodium hydroxide
-solutions and by chlorzinciodide.
-
-
-
-
-                             CHAPTER III
-
-
-                         MECHANICAL TISSUES
-
-
-The =mechanical tissues= of the plant form the framework around
-which the plant body is built up. These tissues are constructed and
-placed in such a manner in the different organs of the plant as to
-meet the mechanical needs of the organ. Many underground stems and
-roots which are subjected to radial pressure have the hypodermal
-and endodermal cells arranged in the form of a non-compressible
-cylinder. Such an arrangement is seen in sarsaparilla root (Plate
-38, Fig. 4). The mechanical tissue of the stem is arranged in the
-form of solid or hollow columns in order to sustain the enormous
-weight of the branches. In roots the mechanical tissue is combined
-in ropelike strands, thereby effectively resisting pulling stresses.
-The epidermis of leaves subjected to the tearing force of the wind
-has epidermal cells with greatly thickened walls, particularly at the
-margin of the leaf. The epidermal cells of most seeds have very thick
-and lignified cell walls, which effectively resist crushing forces.
-
-The cells forming mechanical tissues are: bast fibres, wood
-fibres, collenchyma cells, stone cells, testa epidermal cells, and
-hypodermal and endodermal cells of certain plants. The walls of the
-cells forming mechanical tissues are thick and lignified, with the
-exception of the collenchyma cells and a few of the fibres. Lignified
-cells are as resistive to pulling and other stresses as similar sized
-fragments of steel. The hardness of their wall and their resistance
-to crushing explain the fact that they usually retain their form in
-powdered drugs and foods.
-
-
-                             BAST FIBRES
-
-One of the most important characters to be kept in mind in studying
-bast fibres is the structure of the wall. In fact, the author’s
-classification of bast fibres is based largely on wall structure.
-Such a classification is logical and accurate, because it is based
-upon permanent characters. Another character used in classifying bast
-fibres is the nature of the cell, whether branched or non-branched.
-In fact, this latter character is used to separate all bast fibres
-into two fundamental groups--namely, branched bast fibres and
-non-branched bast fibres. The third important character utilized in
-classifying fibres is the presence or absence of crystals.
-
-  Bast fibres are classified as follows:
-    1. =Crystal bearing.=
-    2. =Non-crystal bearing.=
-
-  The crystal-bearing fibres are divided into two classes:
-    1. =Of leaves.=
-    2. =Of barks.=
-
-  The non-crystal bearing are divided into:
-    1. =Branched.=
-    2. =Non-branched.=
-
-  The branched and non-branched are divided into four classes:
-    1. =Non-porous and non-striated.=
-    2. =Porous and non-striated.=
-    3. =Striated and non-porous.=
-    4. =Porous and striated.=
-
-
-                     CRYSTAL-BEARING BAST FIBRES
-
-The =crystal-bearing fibres= are composed (1) of groups of fibres,
-(2) of crystal cells, and (3) of crystals. In these cases the groups
-of fibres are large, and they are frequently completely covered by
-crystal cells, which may or may not contain a crystal. The crystals
-found on the fibres from the different plants vary considerably in
-size and form. As a rule, the fibres when separated are free of
-crystal cells and crystals. This is so because the crystal cells
-are exterior to the fibres, and in separating the fibres during
-the milling process the crystal cells are broken down and removed
-from the fibres. It is common, therefore, to find isolated fibres
-and crystals associated with the crystal-bearing fibres. The fibres
-which are crystal-bearing may be striated or porous, etc.; but owing
-to the fact that the grouping of the fibres and crystals is so
-characteristic, little or no attention is paid to the structure of
-the individual fibres.
-
-[Illustration: PLATE 19
-
-                   CRYSTAL-BEARING FIBRES OF BARKS
-
-  1. Frangula (_Rhamnus frangula_, L.).
-  2. Cascara sagrada (_Rhamnus purshiana_, D.C.).
-  3. Spanish licorice (_Glycyrrhiza glabra_, L.).
-  4. Witch-hazel bark (_Hamamelis virginiana_, L.).]
-
-
-=Crystal-bearing fibres= occur in the barks of frangula (Plate 19,
-Fig. 1); cascara sagrada (Plate 19, Fig. 2); witch-hazel (Plate 19,
-Fig. 4); in cocillana (Plate 20, Fig. 1); in white oak (Plate 20,
-Fig. 2); in quebracho (Plate 20, Fig. 3); and in Spanish licorice
-root (Plate 19, Fig. 3).
-
-The crystal-bearing fibres of leaves are always associated with
-vessels or tracheids and with cells with chlorophyl. The presence
-or absence of crystal-bearing fibres in leaves should always be
-noted. The crystal-bearing fibres of leaves are composed of fragments
-of conducting cells, fibres, crystal cells, and crystals. The
-crystal-bearing fibres of leaves occur in larger fragments than the
-other parts of the leaf, because the fibres are more resistant to
-powdering. Having observed that a leaf has crystal-bearing fibres,
-in order to identify the powder it is necessary to locate one of the
-other diagnostic elements of the leaf--as the papillæ of coca (Plate
-21, Fig. 1), or the hair of senna (Plate 21, Fig. 3), or the vessels
-in eucalyptus (Plate 21, Fig. 2).
-
-=Branched bast fibres= occur in only a few of the medicinal plants,
-notable examples being tonga root and sassafras root. Occasionally
-one is found in mezereum bark.
-
-The bast fibre of tonga root (Plate 22, Fig. 2) often has seven
-branches, but four- and five-branched forms are more common. The
-walls are non-porous, non-striated, and nearly white.
-
-The bast fibre of sassafras (Plate 22, Fig. 1) has thick, non-porous,
-and non-striated walls, and the branching occurs usually at one end
-only of the fibre. Most of the bast fibres of sassafras root are
-non-branched.
-
-
-                   POROUS AND STRIATED BAST FIBRES
-
-=Porous and striated= walled bast fibres occur in blackberry bark of
-root, wild-cherry bark, and in cinchona bark.
-
-The fibres of blackberry root bark (Plate 23, Fig. 1) have distinctly
-porous and striated walls; the cavity, which is usually greater than
-the diameter of the wall, contains starch. These fibres usually occur
-as fragments.
-
-In wild-cherry bark (Plate 23, Fig. 2) the fibre has short, thick,
-unequally thickened walls, which are porous and striated. Most of the
-fibres are unbroken.
-
-[Illustration: PLATE 20
-
-                   CRYSTAL-BEARING FIBRES OF BARKS
-
-  1. Cocillana (_Guarea rusbyi_, [Britton] Rusby).
-  2. White oak (_Quercus alba_, L.)
-  3. Quebracho (_Aspidosperma quebracho-blanco_, Schlechtendal).]
-
-[Illustration: PLATE 21
-
-                  CRYSTAL-BEARING FIBRES OF LEAVES
-
-  1. Coca leaf (_Erythroxylon coca_, Lam.).
-  2. Eucalyptus leaf (_Eucalyptus globulus_, Labill).
-  3. Senna leaf (_Cassia angustifolia_, Vahl.).]
-
-[Illustration: PLATE 22
-
-                        BRANCHED BAST FIBRES
-
-  1. Sassafras root bark (_Sassafras variifolium_, [Salisb.] Kuntze).
-  2. Tonga root.]
-
-Yellow cinchona bark (Plate 23, Fig. 3) has very thick, prominently
-striated porous-walled fibres, with either blunt or pointed ends. The
-cavity is narrow, and the pores are simple or branched.
-
-
-                 POROUS AND NON-STRIATED BAST FIBRES
-
-=Porous and non-striated= bast fibres occur in marshmallow root and
-echinacea root.
-
-The fibres of marshmallow (Plate 24, Fig. 3) usually occur in
-fragments. The walls have simple pores, and the diameter of the
-cell cavity is very wide; the pores on the upper or lower wall are
-circular or oval in outline (end view).
-
-The bast fibres of echinacea root (Plate 24, Fig. 4) are seldom
-broken; the walls are yellow, the pores are simple and numerous. The
-edges and surface of the fibres are frequently covered with a black
-intercellular substance.
-
-
-                 NON-POROUS AND STRIATED BAST FIBRES
-
-=Non-porous and striated= bast fibres occur in elm bark, stillingia
-root, and cundurango bark. The bast fibres of elm bark (Plate 25,
-Fig. 1) occur in broken, curved, or twisted fragments. The central
-cavity is very small, and the walls are longitudinally striated.
-
-In powdered stillingia root (Plate 25, Fig. 2) the bast fibres are
-broken, and the wall is very thick and longitudinally striated. The
-central cavity is small and usually not visible. Bast fibres of
-cundurango (Plate 25, Fig. 3) are broken in the powder. The cavity
-is very narrow, and the striations are arranged spirally, less
-frequently transversely.
-
-
-               NON-POROUS AND NON-STRIATED BAST FIBRES
-
-=Non-porous and non-striated= walled bast fibres occur in mezereum
-bark, in Ceylon cinnamon, in sassafras root bark, and in soap bark.
-
-The simplest non-porous and non-striated walled bast fibres are found
-in mezereum bark (Plate 26, Fig. 4). The individual fibre is very
-long. It often measures over three millimeters in length, so that in
-the powder the fibre is usually broken. The wall is non-lignified,
-white, non-porous, and of uniform diameter.
-
-[Illustration: PLATE 23
-
-                   POROUS AND STRIATED BAST FIBRES
-
-  1. Blackberry root (_Rubus cuneifolius_, Pursh.).
-  2. Wild cherry (_Prunus serotina_, Ehrh.).
-  3. Yellow cinchona (_Cinchona species_).]
-
-[Illustration: PLATE 24
-
-                 POROUS AND NON-STRIATED BAST FIBRES
-
-  1. Sarsaparilla root (Hypoderm), (_Smilax officinalis_, Kunth).
-  2. Unicorn root (Endoderm).
-  3. Marshmallow root (_Althæa officinalis_, L.).
-  4. Echinacea root (_Echinacea angustifolia_, D. C.).]
-
-[Illustration: PLATE 25
-
-                 NON-POROUS AND STRIATED BAST FIBRES
-
-  1. Elm bark (_Ulmus fulva_, Michaux).
-  2. Stillingia root (_Stillingia sylvatica_, L.).
-  3. Cundurango root bark (_Marsdenia cundurango_, [Triana] Nichols).]
-
-In Ceylon cinnamon (Plate 26, Fig. 2) the bast fibres measure up to
-.900 mm. in length, so that in powdering the bark the fibre is rarely
-broken. These bast fibres, unlike the bast fibres of mezereum, have
-thick, white walls and a narrow cell cavity. Both ends of the fibre
-taper gradually to a long, narrow point.
-
-In Saigon cinnamon the bast fibres are not as numerous as they are
-in Ceylon cinnamon. The individual fibres are thicker than in Ceylon
-cinnamon, and the walls are yellowish and rough and the ends bluntly
-pointed. These fibres are rarely ever free from adhering fragments of
-parenchyma tissue.
-
-In sassafras root bark (Plate 26, Fig. 3) the fibre has one nearly
-straight side--the side in contact with the other bast fibres--and
-an outer side with a wavy outline, caused by the fibre’s pressing
-against parenchyma cells, the point of highest elevation being the
-point of the fibre’s growth into the intercellular space between two
-cells. The outer part of the wall tapers gradually at either end to a
-sharp point. The walls are white, thick, and non-porous.
-
-In soap bark (Plate 26, Fig. 1) the bast fibres have thick, white,
-wavy walls and a narrow cavity. One end of the cell is frequently
-somewhat blunt while the opposite end is slightly tapering.
-
-The branched stone cells of wild-cherry bark have three or more
-branches. The pores are small and usually non-branched, and the
-striations are very fine and difficult to see unless the iris
-diaphragm is nearly closed. The central cavity is very narrow and
-frequently contains brown tannin.
-
-The branched stone cells of hemlock bark are very large; the walls
-are white and distinctly porous bordering on the cell cavity, which
-contains bright reddish-brown masses of tannin.
-
-In cross-section bast fibres occur singly or isolated, as in Saigon
-cinnamon (Plate 34, Fig. 1); or in groups, as in menispermum (Plate
-27, Figs. 1 and 2); or in the form of continuous bands, as in buchu
-stem (Plate 100, Fig. 5).
-
-Bast fibres are seen in longitudinal view in powdered drugs. The cell
-cavity shows throughout the length of the fibre. This cavity differs
-greatly in different fibres. In soap bark (Plate 26, Fig. 1) there is
-scarcely any cell cavity, while in mezereum bark (Plate 26, Fig. 4)
-the cell cavity is very large.
-
-[Illustration: PLATE 26
-
-               NON-POROUS AND NON-STRIATED BAST FIBRES
-
-  1. Soap bark (_Quillaja saponaria_, Molina).
-  2. Ceylon cinnamon bark (_Cinnamomum zeylanicum_, Nees).
-  3. Sassafras root bark (_Sassafras variifolium_, [Salisb.] Kuntze).
-  4. Mezereum bark (_Daphne mezereum_, L.).]
-
-[Illustration: PLATE 27
-
-                        GROUPS OF BAST FIBRES
-
-  1. Menispermum rhizome (_Menispermum canadensis_, L.).
-  2. Althea root (_Althæa officinalis_, L.) showing two groups of bast
-     fibres.]
-
-The pores, which are absent in many drugs, are, when present,
-either simple, as in echinacea root (Plate 24, Fig. 4), or they are
-branched, as in yellow cinchona (Plate 23, Fig. 3).
-
-In each of the above fibres the length and width of the fibre
-are shown. The fibres also have pores of variable length. Such a
-variation is common to most fibres with pores. That part of the wall
-immediately over or below the cell cavity shows the end view or
-diameter of the pore, as in the fibre of marshmallow root (Plate 24,
-Fig. 3). As a rule, however, the pores show indistinctly on the upper
-and lower wall.
-
-
-                    OCCURRENCE IN POWDERED DRUGS
-
-In powdered drugs bast fibres occur singly or in groups. The
-individual fibres may be broken, as in mezereum and elm bark, or they
-may be entire, as in Ceylon cinnamon and in sassafras bark (Plate 26,
-Figs. 2 and 3).
-
-The lignified walls of bast fibres are colored red by a solution of
-phlorogucin and hydrochloric acid, and the walls are stained yellow
-by aniline chloride.
-
-In fact, few of the fibres found in individual plants occur in a
-broken condition.
-
-Isolated bast fibres are circular in outline. Bast fibres, when
-forming part of a bundle, have angled outlines when they are
-completely surrounded by other bast fibres; but when they occur on
-the outer part of the bundle, and when in contact with parenchyma or
-other cortical cells, they are partly angled and partly undulated in
-outline.
-
-In the bast fibres the pores are placed at right angles to the length
-of the fibre. The side walls show the length of the pore (Plate 24,
-Fig. 3); while the upper or lower wall shows the outline, which is
-circular, and the pore, which is very minute.
-
-Most bast fibres have no cell contents. In some cases, however,
-starch occurs, as in the bast fibres of rubus.
-
-The color of the bast fibres varies, being colorless, as in Ceylon
-cinnamon; or yellowish-white, as in echinacea; or bright yellow, as
-in bayberry bark.
-
-Bast fibres retain their living-cell contents until fully developed;
-then they die and function largely in a mechanical way.
-
-The walls of bast fibres are composed of cellulose or of lignin. Most
-of the bast fibres occurring in the medicinal plants give a strong
-lignin reaction.
-
-
-                             WOOD FIBRES
-
-=Wood fibres= always occur in cross-sections associated with vessels
-and wood parenchyma, from which they are distinguished by their
-thicker walls, smaller diameter, and by the nature of the pores,
-which are usually oblique and fewer in number than the pores in the
-walls of wood parenchyma, and different in form from the pores of
-vessels.
-
-The wood fibre on cross-section (Plate 105, Fig. 4) shows an
-angled outline, except in the case of the fibres bordering the
-pith-parenchyma, etc., in which case they are rounded on their outer
-surface, but angled at the points in contact with other fibres. The
-pore of wood fibres is one of the main characteristics which enable
-one to distinguish the wood fibres from bast fibres.
-
-The pores are slanting or strongly oblique (Plate 28, Fig. 2),
-and they show for their entire length on the broadest part of the
-wall--_i.e._, the upper or the lower surface--while in the side wall
-they are oblique; but they are not so distinct as they are on the
-broad part of the wall.
-
-Frequently the pores appear crossed when the upper and the lower wall
-are in focus, because the pores are spirally arranged, and the pore
-on the under wall throws a shadow across the pore on the upper wall,
-or _vice versa_.
-
-Wood fibres always occur in a broken condition (Plate 28, Fig. 1) in
-powdered drugs. These broken fibres usually occur both singly and in
-groups in a given powder.
-
-The color of wood fibres varies greatly in the different medicinal
-woods. Fragments of wood are usually adhering to witch-hazel, black
-haw, and other medicinal barks. In each of these cases the wood
-fibres are nearly colorless. In barberry bark adhering fragments of
-wood and the individual fibres are greenish-yellow. The wood fibres
-of santalum album are whitish-brown; of quassia, whitish-yellow; of
-logwood and santalum rubrum, red.
-
-[Illustration: PLATE 28
-
-                             WOOD FIBRES
-
-  1. White sandalwood (_Santalum album_, L.).
-  2. Quassia wood (_Picræna excelsa_, [Swartz] Lindl.).
-  3. Logwood with crystals (_Hæmatoxylon campechianum_, L.).
-  4. Black haw root (_Viburnum prunifolium_, L.).]
-
-Some wood fibres function as storage cells. In quassia the wood
-fibres frequently contain storage starch. The wood fibres of logwood
-and red saunders contain coloring substances, which are partially in
-the cell cavity and partially in the cell wall.
-
-The walls of wood are composed largely of lignin.
-
-
-                          COLLENCHYMA CELLS
-
-=Collenchyma cells= form the principal medicinal tissue of stems of
-herbs, petioles of leaves, etc. In certain herbs the collenchyma
-forms several of the outer layers of the cortex of the stem. In
-motherwort, horehound, and in catnip the collenchyma cells occur
-chiefly at the angles of the stem. In motherwort (Plate 29, Fig.
-B) there are twelve bundles, one large bundle at each of the four
-angles, and two small bundles, one on either side of the large
-bundle. In catnip (Plate 29, Fig. A) there are four large masses, one
-at each angle of the stem.
-
-Collenchyma cells differ from parenchyma cells in a number of
-ways: first, the cell cavity is smaller; secondly, the walls are
-thicker, the greater amount of thickening being at the angles of the
-cells--that is, the part of the cell wall which is opposite the usual
-intercellular space of parenchyma cells, while the wall common to
-two adjoining cells usually remains unthickened. In horehound stem
-(Plate 30, Fig. 2) the thickening is so great at the angles that no
-intercellular space remains. In the side column of motherwort stem
-(Plate 30, Fig. 1) the thickening between the cells has taken place
-to such an extent that the cell cavities become greatly separated and
-arranged in parallel concentric rows.
-
-The collenchyma of the outer angle of motherwort stem (Plate 30, Fig.
-3) is greatly thickened at the angles. There are no intercellular
-spaces between the cells, and cell cavity is usually angled in
-outline instead of circular, as in the cells of horehound. In certain
-plants intercellular spaces occur between the cells, and the walls
-are striated instead of being non-striated, as in the stems of
-horehound, motherwort, and catnip.
-
-[Illustration: PLATE 29
-
-  _A._ Diagrammatic sketch of the cross-section of catnip stem
-  (_Nepeta cataria_, L.). 1. Collenchyma occurring at the four angles
-  of the stem.
-
-  _B._ Diagrammatic sketch of the cross-section of motherwort stem
-  (_Leonurus cardiaca_, L.). 1, 2, 3. Twelve masses of collenchyma
-  tissue occurring at the four sides of the stem.]
-
-[Illustration: PLATE 30
-
-                          COLLENCHYMA CELLS
-
-  1. Cross-section of a side column of the collenchyma of motherwort
-  stem (_Leonurus cardiaca_, L.).
-
-  2. Cross-section of the collenchyma of horehound stem (_Marrubium
-  vulgare_, L.).
-
-  3. Cross-section of the collenchyma of the outer angle of
-  motherwort stem.]
-
-Collenchyma cells retain their living contents at maturity. Many
-collenchyma cells, particularly of the outer layers of bark and the
-collenchyma of the stems of herbs, contain chlorophyll.
-
-The walls of collenchyma consist of cellulose.
-
-
-                             STONE CELLS
-
-=Stone cells=, like bast fibres, are branched or non-branched. Each
-group is then separated into subgroups according to wall structure
-(whether striated, or pitted and striated, etc.), thickness of wall
-and of cell cavity, color of wall and of cell contents, absence of
-color and of cell contents, etc.
-
-
-                        BRANCHED STONE CELLS
-
-=Branched stone cells= occur in a number of drugs. In witch-hazel
-bark (Plate 31, Fig. 2) the walls are thick, white, and very porous.
-In some cells the branches are of equal length; in others they are
-unequal. In the tea-leaf (Plate 31, Fig. 1) the walls are yellowish
-white and finely porous. When the lower wall is brought in focus, it
-shows numerous circular pits. These pits represent the pores viewed
-from the end. The branches frequently branch or fork.
-
-Branched stone cells also occur in coto bark, acer spicatum,
-star-anise, witch-hazel leaf, hemlock, and wild-cherry barks.
-
-Non-branched stone cells are divided into two main groups, as follows:
-
-  1. Porous and striated stone cells, and,
-  2. Porous and non-striated stone cells.
-
-
-                   POROUS AND STRIATED STONE CELLS
-
-=Porous and striated= walled stone cells occur in ruellia root,
-winter’s bark, bitter root, allspice, and aconite. These stone cells
-are shown in Plate 33, Figs. 1, 2, 3, 4, and 5.
-
-The stone cells of ruellia root (Plate 32, Fig. 1) are greatly
-elongated, rectangular in form, with thick, white, strongly porous
-walls. The central cavity is narrow and is marked with prominent
-pores and striations.
-
-The stone cells of winter’s bark (Plate 32, Fig. 2) vary from
-elongated to nearly isodiametric. The pores are very large, the light
-yellowish wall is irregularly thickened, and the central cavity is
-very large. The pores are prominent.
-
-[Illustration: PLATE 31
-
-                        BRANCHED STONE CELLS
-
-  1. Tea leaf (_Thea sinensis_, L.).
-  2. Witch-hazel bark (_Hamamelis virginiana_, L.).
-  3. Hemlock bark (_Tsuga canadensis_, [L.] Carr).
-  4. Wild-cherry bark (_Prunus serotina_, Ehrh.).]
-
-The stone cell of bitter root (Plate 32, Fig. 3) is nearly
-isodiametric. The walls are yellowish white and strongly porous and
-striated. The central cavity is about equal to the thickness of the
-walls.
-
-The stone cell of allspice (Plate 32, Fig. 4) is mostly rounded in
-form, and when the outer wall only is in focus it shows numerous
-round and elongated pores. The central cavity is filled with masses
-of reddish-brown tannin. The striations are very prominent.
-
-The diagnostic stone cell of aconite (Plate 32, Fig. 5) is
-rectangular or square in outline; the walls are yellowish and the
-central cavity has a diameter many times the thickness of the
-wall. The side and surface view of the pores is prominent, and the
-striations are very fine.
-
-
-                 POROUS AND NON-STRIATED STONE CELLS
-
-=Porous and non-striated stone cells= occur in Ceylon cinnamon, in
-calumba root, in dogwood bark, in cubeb, and in echinacea root.
-
-The diagnostic stone cells of Ceylon cinnamon (Plate 33, Fig. 1) are
-nearly square in outline; the walls are strongly porous and the large
-central cavity frequently contains starch.
-
-The stone cells of calumba root (Plate 33, Fig. 2) vary in shape from
-rectangular to nearly square, and the walls are greenish yellow,
-unequally thickened, and strongly porous. The typical stone cells
-contain several prisms, usually four.
-
-The stone cells of dogwood bark (Plate 33, Fig. 3) have thick, white
-walls with simple and branched pores. The central cavity frequently
-branches and appears black when recently mounted, owing to the
-presence of air.
-
-The stone cells of cubeb (Plate 33, Fig. 4) are very small, mostly
-rounded in outline, with a great number of very fine simple pores
-which extend from the outer wall to the central cavity. The wall is
-yellow and very thick.
-
-The stone cells of echinacea root (Plate 33, Fig. 5) are very
-irregular in form; the walls are yellowish and porous, and the
-central cavity is very large. A black intercellular substance is
-usually adhering to portions of the outer wall.
-
-The color of the walls of the different stone cells is very
-variable. In Ceylon cinnamon and ruellia the walls are colorless;
-in zanthoxylium, light yellow; in rumex, deep yellow; in cascara
-sagrada, greenish yellow.
-
-The pores of stone cells, like the pores of bast fibres, are either
-simple or branched, and they may or may not extend through the entire
-wall. Many of the shorter pores extend for only a short distance from
-the cell cavity.
-
-The width of the cell cavity varies considerably in the stone cells
-of the different plants. In aconite (Plate 32, Fig. 5), in calumba
-(Plate 33, Fig. 2), and in Ceylon cinnamon (Plate 33, Fig. 1), the
-cell cavity is several times greater than the thickness of the cell
-wall.
-
-In allspice (Plate 32, Fig. 4), in bitter root (Plate 32, Fig. 3),
-the diameter of the cell cavity and the thickness of the wall are
-about equal. In cubeb (Plate 33, Fig. 4), in ruellia (Plate 32, Fig.
-1), the wall is thicker than the diameter of the cell cavity.
-
-The cavity of many stone cells contains no characteristic
-cell contents. In other stone cells the cell contents are as
-characteristic as the stone cell. The stone cells of both Saigon and
-Ceylon cinnamon (Plate 33, Fig. 1) contain starch; the stone cells
-of calumba (Plate 33, Fig. 2) contain prisms of calcium oxalate; the
-stone cells of allspice and sweet-birch bark contain tannin.
-
-In cross-sections, stone cells occur singly, as in Saigon cinnamon
-(Plate 34, Fig. 1), ruellia (Plate 34, Fig. 2); in groups, as in
-cascara sagrada (Plate 34, Fig. 3); and in continuous bands, as in
-Saigon cinnamon (Plate 34, Fig. 4).
-
-In powdered drugs, stone cells, like bast fibres, occur singly, as
-in ruellia, calumba, etc.; or in groups, as in cascara sagrada,
-witch-hazel bark, etc. In most powders they occur both singly and in
-groups.
-
-The individual stone cells are mostly entire, as in ruellia, calumba,
-allspice, echinacea, etc. In cascara sagrada many of the stone cells
-are broken when the closely cemented groups are torn apart in the
-milling process. Many of the branched stone cells of witch-hazel bark
-and leaf, wild cherry, etc., also occur broken in the powder.
-
-[Illustration: PLATE 32
-
-                   POROUS AND STRIATED STONE CELLS
-
-  1. Ruellia root (_Ruellia ciliosa_, Pursh.).
-  2. Winter’s-bark (_Drimys winteri_, Forst.).
-  3. Bitterroot (_Apocynum androsæmifolium_, L.).
-  4. Allspice (_Pimenta officinalis_, Lindl.).
-  5. Aconite (_Aconitum napellus_, L.).]
-
-[Illustration: PLATE 33
-
-                 POROUS AND NON-STRIATED STONE CELLS
-
-  1. Ceylon cinnamon (_cinnamomum zeylanicum_, Nees).
-  2. Calumba root (_Jateorhiza palmata_, [Lam.] Miers).
-  3. Dogwood root bark (_Cornus florida_, L.).
-  4. Cubeb (_Piper cubeba_, L., f.)
-  5. Echinacea (_Echinacea angustifolia_, D.C.).]
-
-[Illustration: PLATE 34
-
-  1. Saigon cinnamon.
-  2. Ruellia root (_Ruellia ciliosa_, Pursh.).
-  3. Cascara sagrada (_Rhamnus purshiana_, D.C.).
-  4. Saigon cinnamon.]
-
-The walls of all stone cells are composed of lignin.
-
-The form of stone cells varies greatly; in aconite the stone cells
-are quadrangular; in ruellia they are rectangular; in pimenta,
-they are circular or oval in outline; in most stone cells they are
-polygonal.
-
-The lignified walls of stone cells are stained red with a solution of
-phloroglucin and hydrochloric acid, and the walls are stained yellow
-by aniline chloride.
-
-
-                          ENDODERMAL CELLS
-
-The =endodermal cells= of the different plants vary greatly in form,
-color, structure, and composition of the wall, yet these different
-endodermal cells may be divided into two groups: first, thin-walled
-parenchyma-like cells, and secondly, thick-walled fibre-like cells.
-In the thin-walled endodermal cells the walls are composed of
-cellulose, and the cell terminations are blunt or rounded. When the
-drug is powdered, the cells break up into small diagnostic fragments.
-In the thick-walled endodermal cells, the walls are lignified and
-porous, and the ends of the cell are frequently pointed and resemble
-fibres.
-
-Sarsaparilla root, triticum, convallaria, and aletris have
-thick-walled endodermal cells.
-
-
-                    STRUCTURE OF ENDODERMAL CELLS
-
-The endodermal cells of sarsaparilla root (Plate 35, Fig. 1) are
-never more than one layer in thickness. The walls are porous and of
-a yellowish-brown color. Alternating with the thick-walled cell is a
-thin-walled cell, which is frequently referred to as a passage cell.
-
-The endodermal cells of triticum (Plate 35, Fig. 2) are yellowish,
-and the walls are porous and striated. There are one or two layers
-of cells. The cells forming the outer layer have very thin outer but
-thick inner walls, while the cells forming the inner layer are more
-uniform in thickness.
-
-The endodermal cells of convallaria (Plate 35, Fig. 3) are yellowish
-white in color, and the walls are porous and striated. The outer wall
-of the layer of cells is thinner than the inner wall. The innermost
-layer of cell is more uniformly thickened.
-
-[Illustration: PLATE 35
-
-                CROSS-SECTIONS OF ENDODERMAL CELLS OF
-
-  1. Sarsaparilla root (_Smilax officinalis_, Kunth).
-  2. Triticum (_Agropyron repens_, L.).
-  3. Convallaria (_Convallaria majalis_, L.).
-  4. Aletris (_Aletris farinosa_, L.).]
-
-The endodermal cells of aletris (Plate 35, Fig. 4) are yellowish
-brown, slightly porous and striated. There are one or two layers of
-these cells, and two of the smaller cells usually occupy a space
-similar to that occupied by the radically elongated single cell.
-
-On a longitudinal view, the endodermal cells of sarsaparilla
-triticum, convallaria, and aletris appear as follows:
-
-Those of sarsaparilla (Plate 36, Fig. 1) are greatly elongated, the
-ends of the cells are blunt or slightly pointed, and the walls appear
-porous and striated.
-
-Those of triticum (Plate 36, Fig. 2) are elongated, the walls are
-porous and striated, and the outer wall is much thinner than the
-inner wall. The end wall between two cells frequently appears common
-to the two cells.
-
-Those of convallaria (Plate 36, Fig. 3) are elongated, and the end
-wall is usually blunt. The outer wall is thinner than the inner wall.
-
-Those of aletris (Plate 36, Fig. 4) are fibre-like in appearance; the
-ends of the cells are pointed and the wall is strongly porous. The
-longitudinal view of these cells is shown in plate 36.
-
-
-                          HYPODERMAL CELLS
-
-=Hypodermal cells= occur in sarsaparilla root and in triticum.
-In the cross-section of sarsaparilla root (Plate 37, Fig. 1) the
-hypodermal cells are yellowish or yellowish brown. The outer wall is
-thicker than the inner wall, and the cell cavity is mostly rounded,
-and contains air. The walls are porous and finely striated. On
-longitudinal view, the hypodermal cells of sarsaparilla (Plate 37,
-Fig. 2) are greatly elongated, and the outer and side walls are
-thicker than the inner walls. The ends of the cells are blunt and
-distinct from each other.
-
-In cross-section, the hypodermal cells of triticum (Plate 37, Fig. 3)
-are nearly rounded in outline, and the walls are of nearly uniform
-thickness. In longitudinal view (Plate 37, Fig. 4) the same cells
-appear parenchyma-like, and the walls between any two cells appear
-common to the two cells.
-
-[Illustration: PLATE 36
-
-              LONGITUDINAL SECTIONS OF ENDODERMAL CELLS
-
-  1. Sarsaparilla root (_Smilax officinalis_, Kunth).
-  2. Triticum (_Agropyron repens_, L.).
-  3. Convallaria (_Convallaria majalis_, L.).
-  4. Aletris (_Aletris farinosa_, L.).]
-
-[Illustration: PLATE 37
-
-                          HYPODERMAL CELLS
-
-  1. Cross-section sarsaparilla root (_Smilax officinalis_, Kunth).
-  2. Longitudinal section sarsaparilla root (_Smilax officinalis_,
-     Kunth).
-  3. Cross-section triticum (_Agropyron repens_, L.).
-  4. Longitudinal section triticum (_Agropyron repens_, L.).]
-
-
-
-
-                             CHAPTER IV
-
-                          ABSORPTION TISSUE
-
-
-Most plants obtain the greater part of their food, first, from the
-soil in the form of a watery solution, and, secondly, from the air
-in the form of a diffusible gas. In a few cases all food material is
-obtained from the air, as in the case of epiphytic plants. In such
-plants, the aerial roots have a modified outer layer--velamen--which
-functions as a water-absorbing and gas-condensing tissue. Many
-xerophytic plants absorb water through the trichomes of the leaf.
-Such absorption tissue enables the plant to absorb any moisture that
-may condense upon the leaf and that would not otherwise be available
-to the plant. The water-absorbing tissue of roots is restricted to
-the root hairs, which are found, with few exceptions, only on young
-developing roots.
-
-
-                             ROOT HAIRS
-
-=Root hairs= usually occur a short distance back of the root cap.
-There is, in fact, a definite zone of the epidermis on which the root
-hairs develop. This zone is progressive. As the root elongates the
-root hairs continue to develop, the zone of hairs always remaining at
-about the same distance from the root cap. With the development of
-new zones of growth the hairs on the older zone die off and finally
-become replaced by an epidermis, or a periderm, except in the case of
-sarsaparilla root, and possibly other roots that have persistent root
-hairs.
-
-Each root hair is an outgrowth from an epidermal cell (Plate 38, Fig.
-3). The length of the hair and its form depend upon the nature of the
-soil, whether loose or compact, and upon the amount of water present.
-
-A root hair is formed by the extension of the peripheral wall of
-an epidermal cell. At first this wall is only slightly papillate,
-but gradually the end wall is extended farther and farther from
-the surface of the root, caused by the development of side walls by
-the growing tip of the root hair until a tube-like structure, root
-hair, is produced. The root hair is then a modified epidermal cell.
-The protoplast lines the cell, and the central part of the root
-hair consists of a large vacuole filled with cell sap. The wall of
-the root hair is composed of cellulose, and the outermost part is
-frequently mucilaginous. As the root hairs develop, they become bent,
-twisted, and of unequal diameter, as a result of growing through
-narrow, winding soil passages. During their growth, the root hairs
-become firmly attached to the soil particles. The walls of root hairs
-give an acid reaction caused by the solution of the carbon dioxide
-excreted by the root hair. The acid character of the wall attracts
-moisture, and in addition has a solvent action on the insoluble
-compounds contained in the soil. It will thus be seen that the method
-of growth, structure, composition, and reaction of the wall of the
-root hair is perfectly suited to carry on the work of absorbing the
-enormous quantities of water needed by the growing plant. It is
-a well-known fact that when two solutions of unequal density are
-separated by a permeable membrane, the less dense liquid will pass
-through the membrane to the denser liquid. The wall of the root hair
-acts like an osmotic membrane. The less dense watery solution outside
-the root hair passes through its wall and into the denser cell sap
-solution. As the solution is absorbed, it passes from the root hair
-into the adjoining cortical parenchyma cells.
-
-It is a fact that root hairs are seldom found in abundance on
-medicinal roots. This is due to the fact that root hairs occur
-only on the smaller branches of the root, and that when the root
-is pulled from the ground the smaller roots with their root hairs
-are broken off and left in the soil. For this reason a knowledge of
-the structure of root hairs is of minor importance in the study of
-powdered drugs. An occasional root hair is found, however, in most
-powdered roots, but root hairs have little or no diagnostic value,
-except in false unicorn root and sarsaparilla. When false unicorn
-root is collected, most of the root hairs remain attached to the
-numerous small fibrous roots, owing to the fact that these roots are
-easily removed from the sandy soil in which the plants grow. The
-root hairs of false unicorn are so abundant and so large that they
-form dense mats, which are readily seen without magnification. These
-hairs are, therefore, macroscopically as well as microscopically
-diagnostic. The root hairs of false unicorn (Plate 39, Fig. 2) have
-white, wavy, often decidedly indented walls. The terminal, or end
-wall, is rounded and much thicker than the side walls.
-
-[Illustration: PLATE 38
-
-  CROSS-SECTION OF SARSAPARILLA ROOT (_Smilax officinalis_, Kunth)
-
-  1. Epidermal cell developing into a root hair.
-  2. Developing root hair.
-  3. Nearly mature root hair.
-  4. Hypodermal cells.]
-
-[Illustration: PLATE 39
-
-                       ROOT HAIRS (Fragments)
-
-  1. Sarsaparilla root (_Smilax officinalis_, Kunth).
-  2. False unicorn root (_Helonias bullata_, L.).]
-
-In sarsaparilla (Plate 39, Fig. 1) the root hairs are curved and
-twisted. The end wall is thicker than the side walls. In some hairs
-the walls are as thick as the walls of the thin-walled bast fibres.
-This accounts for the fact that the root hairs are persistent on
-even the older portions of sarsaparilla root, and it serves also to
-explain why these root hairs remain on the root even after being
-pulled from the firmly packed earth in which the root grows.
-
-
-                     WATER ABSORPTION BY LEAVES
-
-In many xerophytic terrestrial plants, the trichomes occurring on
-leaves act as a water-absorbing tissue. In such plants the walls
-of the hairs are composed largely of cellulose. It is obvious that
-these hairs absorb the water of condensation caused by dew and light
-rains--water which could not reach the plant except by such means.
-
-There is no special tissue set aside for the absorption of gases from
-the air. Carbon dioxide, which contributes the element carbon to the
-starch formed by photosynthesis, enters the leaf by way of the stoma
-and lenticels. The structure and the chief functions of these will be
-considered under aërating tissue.
-
-
-
-
-                              CHAPTER V
-
-                          CONDUCTING TISSUE
-
-All cells of which the primary or secondary function is that
-of conduction are included under conducting tissue. It will be
-understood how important the conducting tissue is when the enormous
-quantity of water absorbed by a plant during a growing season is
-considered. It will then be realized that the conducting system must
-be highly developed in order to transport this water from one organ
-to another, and, in fact, to all the cells of the plant. Special
-attention must be given to the occurrence, the structure, the
-direction of conduction, and to the nature of the conducted material.
-
-The cells or cell groups comprising the conducting tissue are vessels
-and tracheids, sieve tubes, medullary ray cells, latex tubes, and
-parenchyma.
-
-
-                               VESSELS
-
-=Vessels= and =tracheids= form the principal upward conducting tissue
-of plants. They receive the soil water expressed from the cortical
-parenchyma cells located in the region of the root, immediately
-back of the root hair zone. This soil water, with dissolved crude
-inorganic and organic food materials, after entering the vessels
-and tracheids passes up the stem. The cells needing water at the
-different heights absorb it from the vessels, the excess finally
-reaching the leaves. When the stem branches, the water passes into
-the vessels of the branches and finally to the leaves of the branch.
-In certain special cases the vessels conduct upward soluble food
-material. In spring sugary sap flows upward through the vessels of
-the sugar maple.
-
-Vessels are tubes, often of great length, formed from a number of
-superimposed cells, in which the end walls have become absorbed.
-The vessels therefore offer little resistance to the transference
-of water from the roots to the leaves of a plant. The combined
-length of the vessels is about equal to the height of the plant in
-which they occur. The length of the individual vessels varies from a
-fraction of a meter up to several meters.
-
-
-                           ANNULAR VESSELS
-
-The =annular vessels= are thickened at intervals in the form of rings
-(Plate 40, Fig. 1), which extend outward from and around the inner
-wall of the vessel. In fact, it is the inner wall which is thickened
-in all the different types of vessels. The ring-like thickening
-usually separates from the wall when the drug is powdered. Such
-separated rings occur frequently in powdered digitalis, belladonna,
-and stramonium leaves. Annular vessels are not, however, of
-diagnostic importance, because more characteristic cells are found in
-the plants in which they occur. Not infrequently a vessel will have
-annular thickenings at one end and spiral thickenings at the other.
-Such vessels are found in the pumpkin stem (Plate 40, Fig. 1).
-
-Vessels are distinguished from other cells by their arrangement, by
-their large size when seen in cross-section, and by the thickening
-of the wall when seen in longitudinal sections of the plant or in
-powders. The side walls of vessels are thickened in a number of
-striking yet uniform ways. The chief types of thickening of the wall,
-beginning with one that is the least thickened, are annular, spiral,
-sclariform, pitted, and pitted with bordered pores.
-
-
-                           SPIRAL VESSELS
-
-In the =spiral vessel= the thickening occurs in the form of a
-spiral, which is readily separated from the side walls. This is
-particularly the case in powdered drugs, where the spiral thickening
-so frequently separates from the cell wall. There are three types of
-spiral vessels: those with one (Plate 41, Fig. 1), those with two,
-and those with three spirals. Single spirals occur in most leaves;
-double spirals occur in many plants (Plate 41, Fig. 2), but they
-are particularly striking in powdered squills. Triple spirals are
-characteristic of the eucalyptus leaf (Plate 41, Fig. 3); in fact,
-they form a diagnostic feature of the powder. Frequently a spirally
-thickened wall indicates a developmental stage of the vessel. Many
-such vessels are spirally thickened at first, but later, when
-mature, an increased amount of thickening occurs and the vessel
-becomes a reticulate or pitted vessel. Many mature vessels, however,
-are spirally thickened as indicated above. In herbaceous stems and
-in certain roots and leaves spiral vessels are associated with the
-sclariform reticulate and pitted type. In certain cases a single
-spiral band will branch as the vessel matures.
-
-There is a great variation in the amount of spiral thickening
-occurring in a vessel. In leaves, particularly, the spiral appears
-loosely coiled; while in squills and other rhizomes and roots the
-spiral appears as a series of rings. When viewed by high power only
-half of each spiral band is visible. At either side of the cell the
-exact size and form of the thickening appear in two parallel rows of
-dark circles or projections from the walls. This thickening of the
-wall is rendered visible from the fact that the light is retarded as
-it passes through that portion of the spiral extending from the upper
-to the under side of the spiral; while the light readily traverses
-the upper and lower cross bands of the vessel.
-
-It should be remembered that, when the upper part of the spiral
-vessel is in focus, the bands appear to bend in a direction away from
-the eye; while when the under side of the bands are in focus, the
-bands appear to bend toward the eye. These facts will show that it
-is necessary to focus on both the upper and lower walls in studying
-spiral vessels. In double spiral vessels the spirals are frequently
-coiled in opposite directions; therefore the bands appear to cross
-one another. In eucalyptus leaf the three bands are coiled in the
-same direction. In all cases the thickening occurs on all sides of
-the wall. Its appearance will, therefore, be the same no matter at
-what angle the vessel is viewed.
-
-
-                         SCLARIFORM VESSELS
-
-=Sclariform vessels= have interrupted bands of thickening on the
-inner walls. Two or more such bands occur between the two side walls.
-The series of bands are separated by uniformly thickened portions of
-the wall extending parallel to the length of the vessel. Sclariform
-vessels are usually quite broad, so that it is necessary to change
-the focus several times in order to bring the different series of
-bands in focus. The series of bands are usually of unequal width and
-length.
-
-[Illustration: PLATE 40
-
-                     ANNULAR AND SPIRAL VESSELS
-
-  1. Pumpkin stem (_Cucurbita pepo_, L.).
-  2. Two characteristic views of spiral vessels.
-  3. (_A_) Upper part of spiral vessel in focus.
-     (_B_) Under part of spiral vessel in focus.
-  4. Spiral vessel of the disk petal matricaria (_Matricaria
-       chamomilla_, L.).]
-
-[Illustration: PLATE 41
-
-SPIRAL VESSELS
-
-  1. Single spiral vessel of pumpkin stem (_Cucurbita pepo_, L.).
-  2. Double spiral vessel of squill bulb (_Urginea maritima_, [L.]
-     Baker).
-  3. Triple spiral vessel of eucalyptus leaf (_Eucalyptus globulus_,
-     Labill).]
-
-Sclariform vessels occur in male fern (Plate 42, Fig. 2), calamus,
-tonga root (Plate 42, Fig. 3), and sarsaparilla (Plate 42, Fig. 1).
-In each they are characteristic. Sclariform vessels, with these few
-exceptions, do not occur in drug plants. In fact, drugs derived from
-dicotyledones rarely have sclariform vessels. They occur chiefly
-in the ferns and drugs derived from monocotyledenous plants. Their
-presence or absence should, therefore, be noted when studying
-powdered drugs.
-
-
-                         RETICULATE VESSELS
-
-=Reticulate vessels= are of common occurrence in medicinal plants. In
-fact, they occur more frequently than any other type of vessel. The
-basic structure of reticulate vessels (Plate 43, Fig. 1) occurring in
-different plants is similar, but they vary in a recognizable way in
-different plants (Plate 43, Fig. 2). The walls of reticulate vessels
-are thickened to a greater extent than are the walls of spirally
-thickened vessels.
-
-
-                           PITTED VESSELS
-
-=Pitted vessels= are met with most frequently in woods and
-wood-stemmed herbs. There are two distinct types of pitted
-vessels--_i.e._, simple pitted vessels and pitted vessels with
-bordered pores.
-
-The pitted vessel represents the highest type of cell-wall
-thickening. The entire wall of the vessel is thickened, with the
-exception of the places where the pits occur. The number and size of
-the pits vary greatly in different drugs. In quassia (Plate 44, Fig.
-1) the pits are numerous and very small, and the openings are nearly
-circular in outline. In white sandalwood (Plate 44, Fig. 3). the pits
-are few in number, but when they do occur they are much larger than
-are the pits of quassia.
-
-
-                 PITTED VESSELS WITH BORDERED PORES
-
-=Pitted vessels with bordered pores= are of common occurrence in the
-woody stems and stems of many herbaceous plants (Plate 45, Figs. 3
-and 4). In such vessels the wall is unthickened for a short distance
-around the pits. This unthickened portion may be either circular or
-angled in outline, a given form being constant to the plant in which
-it occurs. The pits vary from oval to circular. Pitted vessels with
-bordered pores occur in belladonna and aconite stems.
-
-[Illustration: PLATE 42
-
-                         SCLARIFORM VESSELS
-
-  1. Sarsaparilla root (_Smilax officinalis_, Kunth).
-  2. Male fern (_Dryopteris marginalis_, [L.] A. Gray).
-  3. Tonga root.]
-
-[Illustration: PLATE 43
-
-                         RETICULATE VESSELS
-
-  1. Hydrastis rhizome (_Hydrastis canadensis_, L.).
-  2. Musk root (_Ferula sumbul_, [Kauffm.] Hook., f.).]
-
-[Illustration: PLATE 44
-
-                           PITTED VESSELS
-
-  1. Quassia, low magnification (_Picræna excelsa_, [Swartz] Lindl.).
-  2. Quassia, high magnification.
-  3. White sandalwood (_Santalum album_, L.).]
-
-[Illustration: PLATE 45
-
-                               VESSELS
-
-  1. Reticulate vessel of calumba root (_Jateorhiza palmata_, [Lam.]
-       Miers).
-  2. Reticulate tracheid of hydrastis rhizome (_Hydrastis
-       canadensis_, L.).
-  3. Pitted vessel with bordered pores of belladonna stem.
-  4. Pitted vessel with bordered pores of aconite stem (_Aconitum
-       napellus_, L.).]
-
-Vessels and tracheids lose their living-cell contents when fully
-developed. In the vessels the cell contents disappear at the period
-of dissolution of the cell wall.
-
-The walls of vessels and tracheids are composed of lignin, a
-substance which prevents the collapsing of the walls when the
-surrounding cells press upon them, and which also prevents the
-tearing apart of the wall when the vessel is filled with ascending
-liquids under great pressure. Lignin thus enables the vessel to
-resist successively compression and tearing forces.
-
-Tracheids are formed from superimposed cells with oblique perforated
-end walls. The side walls of tracheids are thickened in a manner
-similar to those of vessels. The tracheids in golden seal are of a
-bright-yellow color, and groups of these short tracheids scattered
-throughout the field form the most characteristic part of the
-powdered drug. In ipecac root the tracheids are of a porcelain-white,
-translucent appearance, and they are much longer than are the
-tracheids of golden seal.
-
-The cellulose walls of parenchyma cells are stained blue with
-hæmatoxylin and by chlorzinciodide. Cellulose is completely soluble
-in a fresh copper ammonia solution.
-
-
-                             SIEVE TUBES
-
-=Sieve tubes= are downward-conducting cells. They conduct downward
-proteid food material. This fact is easily demonstrated by adding
-iodine to a section containing sieve tubes, in which case the sieve
-tubes are turned yellow.
-
-Developing sieve tubes have all the parts common to a living cell;
-but when fully mature, however, the nucleus becomes disorganized, but
-a layer of protoplasm continues to line the cell wall.
-
-Sieve tubes (Plate 46, Fig. 1) are composed of a great number of
-superimposed cells with perforated end walls and with non-porous
-cellulose side walls. The end walls of two adjoining cells are
-greatly thickened and the pores pass through both walls. This
-thickened part of the porous end walls of two sieve cells is called
-the sieve plate, and it may be placed in an oblique or a horizontal
-position.
-
-[Illustration: PLATE 46
-
-  1. Longitudinal section of sieve tube (_Cucurbita pepo_, L.).
-  2. Cross-section of sieve tube just above an end wall--sieve plate.]
-
-In a longitudinal section the sieve tubes are seen to be slightly
-bulging at the sieve plate, and through the pores extend protoplasmic
-strands. The strands are united on the upper and lower side of
-the sieve plate to form the protoplasmic strands of the living
-sieve tubes and the callus, layers of dried plants. This callus is
-frequently yellowish in color, and in all cases is separated from the
-cell wall. In certain plants the sieve plate occurs on the side walls
-of the sieve tubes in contact with other sieve tubes.
-
-
-                             SIEVE PLATE
-
-=Sieve plates= on cross-section (Plate 46, Fig. 2) are polygonal
-in outline, and the pores are either round or angled. Large sieve
-tubes and sieve plates occur in pumpkin stem; but, almost without
-exception, in drug plants the sieve tubes are small and the sieve
-plate is inconspicuous. When the drug is powdered, the sieve tubes
-break up into undiagnostic fragments. When studying sections of the
-plants, the extent, size, and arrangement of the sieve tubes must
-always be noted.
-
-
-                 MEDULLARY BUNDLES, RAYS, AND CELLS
-
-                              Function
-
-The medullary ray cells are the lateral conducting cells of the
-plant. They conduct outwardly the water and inorganic salts brought
-up from the roots by the vessels and tracheids; and they conduct
-inwardly toward the centre of the stem the food material manufactured
-in the leaves and brought down by the sieve cells. The medullary rays
-thus distribute the inorganic and organic food to the living cells of
-the plant, and they conduct the reserve food material to the storage
-cells, and, lastly, they function in certain plants as storage cells.
-
-
-                             Occurrence
-
-The form, size, wall structure, and the distribution of the medullary
-ray bundles, rays, and cells are best ascertained by studying:
-first, the cross-section of the plant; secondly, the radial section;
-and, thirdly, the tangential section.
-
-Students should be careful to distinguish between the medullary ray
-bundle, the medullary ray, and the medullary ray cell. In some plants
-the bundles are only one cell wide, but in other plants the medullary
-ray bundle is more than one cell wide, frequently several cells wide.
-
-
-                      THE MEDULLARY RAY BUNDLE
-
-The =medullary ray bundle= is made up of a great many medullary ray
-cells. These bundles (Plate 106, Fig. 5) are of variable length,
-height, and width. The bundles are isolated, and they occur among
-and separate the other cells of the plants in which they occur.
-Tangential sections show the medullary ray bundle in cross-section.
-Such sections are lens-shaped, and they show both the width and the
-height of the medullary ray bundle. The length of the medullary ray
-bundle is shown in cross-sections.
-
-
-                          THE MEDULLARY RAY
-
-The =medullary ray= (Plate 47) is a term used to indicate that part
-of a medullary ray bundle which is seen in cross-sections and in
-radial sections. In cross-sections the length of the ray will be as
-great as the length of the bundle, and the width of the ray will be
-as great as the width of the medullary ray bundle at the point cut
-across. In longitudinal sections the medullary ray will differ in
-height according to the thickness of the bundle at the point cut.
-
-When the medullary rays extend from the centre of the stem to the
-middle bark, they are termed primary medullary rays; when they extend
-from the cambium circle to the middle bark, they are termed secondary
-medullary rays. As the plant grows, the diameter of the organ becomes
-greater and the number of medullary rays are increased. In each of
-these cases the medullary rays may be one or more than one cell wide,
-according to whether the medullary ray bundle is one or more than one
-cell wide. Even in the same plant the width of the medullary rays
-will vary if the bundle is more than one cell wide, according to
-width of the medullary ray bundle at the point cut across.
-
-[Illustration: PLATE 47
-
-           RADIAL LONGITUDINAL SECTION OF WHITE SANDALWOOD
-                       (_Santalum album_, L.)
-
-  1. Medullary ray.
-  2. Wood fibres and wood parenchyma.]
-
-On cross-section the medullary rays are seen to vary greatly. In many
-plants they are more or less straight radial lines, as in quassia
-(Plate 105, Fig. 2); while in other plants they form wavy lines
-where they bend or curve around the conducting cells, as in piper
-methysticum, kava-kava (Plate 48, Fig. A).
-
-In the study of powdered drugs the radial view of the medullary rays
-is most frequently seen.
-
-In a perfect radial section (Plate 107, Fig. 2) the medullary rays
-are seen as tiers of cells in contact throughout their long diameter,
-and they run at right angles to the long diameter of the other cells.
-This view of the rays shows the length and height of the medullary
-ray. In logwood the rays are often forty cells high. In powdered
-barks, woods (Plate 47), and woody roots the radial view of the
-medullary rays is frequently diagnostic.
-
-In guaiacum officianale wood the medullary rays are one cell wide on
-cross-section, and up to six cells high on the tangential section.
-In santalum album the rays are from one to three cells wide on
-cross-section, and up to six cells high on tangential section. In the
-greater number of plants the rays are more than one cell wide.
-
-
-                       THE MEDULLARY RAY CELL
-
-The =medullary ray cell= (Plate 48, Fig. 1) is one of the individual
-cells making up the medullary ray bundle and the medullary ray.
-
-The cross-sections of the cells which are seen in tangential sections
-show the cells to be mostly circular in outline when they occur in
-the central portion of medullary ray bundles of more than two cells
-in width; but they are more irregular in outline when the medullary
-ray bundle is only one cell wide. Even the cells of the three or more
-cell-wide bundles have irregular, outlined cells at the ends of the
-bundle and on the sides in contact with the other tissues.
-
-The length and height of the medullary ray cell are shown in radial
-sections; while the width and length of the medullary ray cells are
-shown in cross-sections.
-
-
-                         Structure of Cells
-
-The structure of the individual cells forming the medullary rays
-differs greatly in different plants, but is more or less constant in
-structure in a given species.
-
-The medullary rays of the wood usually have strongly pitted side and
-end walls, while the medullary rays of most barks are not at all, or
-only slightly, pitted. In most plants the cells are of nearly uniform
-size. Frequently, however, the cells vary in size in a given ray, as
-shown in the cross-section of kava-kava.
-
-
-                  Arrangement of the Cells in a Ray
-
-The union of any two cells in a ray is also of importance. In
-quassia the medullary ray cells have oblique end walls, so that on
-cross-section the line of union between two cells is an oblique
-wall. In most plants the medullary ray cells have blunt or square or
-oblique end walls, so that the line of union is a straight line.
-
-In most plants the cells are much longer than broad, but the cells of
-sassafras bark are nearly as broad as long.
-
-The walls of the cortical medullary ray cells and the medullary rays
-of most roots and stems of herbs are composed of cellulose; while
-the walls of medullary ray cells occurring in woods are frequently
-lignified.
-
-There is a great variation in the character of the cell contents of
-medullary rays. In white pine bark (Plate 48, Fig. B1) are deposits
-of tannin; in quassia wood, starch; in canella alba, rosette crystals
-of calcium oxalate, etc.
-
-
-                             LATEX TUBES
-
-Living =latex tubes=, like sieve tubes, have a layer of protoplasm
-lining the walls, and, in addition, have numerous nuclei. In drug
-plants the nuclei are not distinguishable, but the protoplasm is
-always clearly discernible.
-
-[Illustration: PLATE 48
-
-  _A._ Cross-section of kava-kava root (_Piper methysticum_,
-       Forst., f.).
-     1. Unequal diameter medullary ray cells.
-     2. Vessels.
-     3. Wood parenchyma.
-     4. Wood fibres.
-
-  _B._ Cross-section of white pine bark (_Pinus strobus_, L.).
-     1. Wavy medullary rays with tannin.
-     2. Parenchyma cells.
-     3. Sieve cells.]
-
-Latex tubes function both as storage and as conducting cells. They,
-like the sieve tubes, contain proteid substances chiefly, yet
-frequently starch is found. The cells bordering the latex tubes
-absorb from them, as needed, the soluble food material. While our
-knowledge concerning the function of latex in some plants is meagre,
-still in other plants it is practically certain that the latex is
-composed of nutritive substances which are utilized by the plant as
-food. In certain other plants the latex appears to be used as a means
-of resisting insect attacks and as a protection against injury.
-
-There are two types of latex tubes common to plants, namely, latex
-cells and latex vessels. Latex tubes developing from a single cell do
-not differ materially from a latex tube originating from the fusion
-of several cells. In each case the latex tube branches to such an
-extent that it bears no resemblance to ordinary cells. It would seem
-that the ultimate branches are formed and develop in much the same
-manner as root hairs--that is, by a growing tip of the branch. A
-mature plant may therefore have latex tubes with almost numberless
-branches (Plate 50, Fig. 1) and be of very great length.
-
-The branches of latex tubes develop in such an irregular manner that
-it is possible to obtain a cross and a longitudinal section of the
-latex tubes by making a cross-section of stem. Such a section is
-shown in the drawing of the cross-section of the rhizome of black
-Indian hemp (Plate 49, Fig. B).
-
-The color of the latex in medicinal plants varies from a gray white
-in papaw (carica papaya), aromatic sumac, black Indian hemp, and
-bitter root, to white in the opium poppy, light orange in celandine,
-and deep orange in bloodroot (Plate 50, Fig. 2). In each of these
-cases it is the latex which yields the important medicinal products.
-
-
-                             PARENCHYMA
-
-The larger amount of plant tissue is composed of =parenchyma= cells.
-These cells vary from square to oblong, or they may be irregular and
-branched. The end walls are square or blunt, and the wall is composed
-of cellulose, with the exception of the wood parenchyma, which has
-lignified walls.
-
-There are seven characteristic types of parenchyma cells: (1)
-cortical parenchyma, (2) pith parenchyma, (3) wood parenchyma,
-(4) leaf parenchyma, (5) aquatic plant parenchyma, (6) endosperm
-parenchyma, (7) phloem parenchyma.
-
-[Illustration: PLATE 49
-
-  _A._ Cross-section of black Indian hemp (_Apocynum cannabinum_, L.).
-     1. Longitudinal section of a latex tube.
-     2. Cross-section of latex tube.
-     3. Parenchyma.
-
-  _B._ Cross-section of a part of black Indian hemp root.
-     4. Cross-section of a large latex tube.
-     5. Parenchyma.]
-
-[Illustration: PLATE 50
-
-                            LATEX VESSELS
-
-  1. Radial-longitudinal section of dandelion root (_Taraxacum
-     officinale_, Weber).
-  2. Cross-section of sanguinaria root (_Sanguinaria canadensis_, L.).
-  3. Cross-section of dandelion root.]
-
-Parenchyma cells, cortical, pith, aquatic plant, leaf, flower,
-and endosperm, conduct in all directions--upward, downward, and
-laterally. The direction of conduction depends upon the needs of the
-different cells forming the plant. The fluids pass from the cell with
-an abundance of cell sap to the cell with less cell sap. In this wall
-all cells are provided with food.
-
-Parenchyma cells conduct water absorbed by the roots and soluble
-carbohydrate material chiefly.
-
-The walls of all the different types of parenchyma cells are composed
-of cellulose with the exception of the wood parenchyma cells,
-the walls of which are lignified. The end walls of non-branched
-parenchyma cells and the cell terminations of branched cells are very
-blunt.
-
-
-                         CORTICAL PARENCHYMA
-
-=Cortical parenchyma= (Plate 51) differs greatly in size, thickness
-of the walls, and arrangement. A study of the longitudinal sections
-of different parts of medicinal plants reveals the fact that the
-cortical parenchyma cells form superimposed layers in which the end
-walls are either parallel, in which case the arrangement resembles
-that of several rows of boxes standing on end, or the end walls of
-the cells alternate with each other, in which case the arrangement is
-similar to that of the arrangement of the bricks in a building.
-
-In certain plants the cortical parenchyma cells are long and narrow
-and rectangular in shape, while in other plants the cells, although
-still rectangular in outline, are very broad and approach the square
-form.
-
-All typical cortical parenchyma cells have uniformly thickened
-non-pitted walls. In most barks the parenchyma cells beneath the
-bark are elongated tangentially, but are very narrow radially. The
-cells are always arranged around intercellular spaces, which vary
-from triangular, quadrangular, etc., according to the number of cells
-bordering the intercellular space.
-
-
-                           PITH PARENCHYMA
-
-=Pith parenchyma= (Plate 52) differs from cortical parenchyma cells
-chiefly in the character of the walls, which are usually thicker and
-always pitted.
-
-[Illustration: PLATE 51
-
-                          PARENCHYMA CELLS
-
-  1. Longitudinal section of the cortical parenchyma of celandine
-  root (_Chelidonium majus_, L.) 2. Cross-section of the cortical
-  parenchyma of sarsaparilla root (_Smilax officinalis_, Kunth).]
-
-[Illustration: PLATE 52
-
-    _A._ Longitudinal section of the pith parenchyma of grindelia stem
-       (_Grindelia squarrosa_, [Pursh] Dunal).
-     1. Cell cavity.
-     2. Cross-section of the porous end wall.
-     3. Surface view of the porous side wall.
-  _B._ Cross-section of the pith parenchyma of grindelia stem.
-     1. Cell cavity.
-     2. Porous walls.
-     3. Pitted end walls.]
-
-
-                           LEAF PARENCHYMA
-
-The =parenchyma cells= (Plate 109, Fig. 1) of leaves, of flower
-petals, and the parenchyma cells of some aquatic plants are branched;
-that is, each cell has more than two cell terminations. These cell
-terminations are frequently quite attenuated and usually very blunt.
-Such a cell structure provides for a greater amount of intercellular
-space and a maximum exposure of surface. This arrangement makes it
-possible for the parenchyma cells of the leaf to absorb more readily
-the enormous amount of carbon dioxide needed in the photosynthetic
-process.
-
-
-                      AQUATIC PLANT PARENCHYMA
-
-The =parenchyma of aquatic plants= (Plate 59) has large intercellular
-spaces formed by the chains of cells.
-
-
-                           WOOD PARENCHYMA
-
-=Wood parenchyma= (Plate 105, Fig. 3) cells are the narrowest
-parenchyma cells occurring in the plant. Their walls are always
-lignified and strongly pitted, and in some cases the end walls common
-to two cells are obliquely placed.
-
-
-                          PHLOEM PARENCHYMA
-
-=Phloem parenchyma= (Plate 100, Fig. 8) cells are usually associated
-with sieve cells. They are very long, narrow, and have thin,
-non-pitted walls. The thinness of the walls undoubtedly enables the
-cells to conduct diffusible food substance more quickly than the
-cortical parenchyma cells.
-
-
-                         PALISADE PARENCHYMA
-
-=Palisade parenchyma= of leaves is of the typical parenchyma shape
-and the end walls are placed nearly on a plane, even when more than
-one layer is present. The cells are very small, however, and the
-walls are very thin and non-pitted.
-
-
-
-
-                             CHAPTER VI
-
-                           AERATING TISSUE
-
-
-The =aerating tissue= of the plant performs a threefold function:
-first, it permits the exchange of gases during photosynthesis;
-secondly, it permits the entrance of oxygen and the exit of carbon
-dioxide during respiration; and, thirdly, it permits the exit of the
-excess of water absorbed by the plant.
-
-The above functions are carried on by the stomata, the water-pores,
-the lenticels, and the intercellular spaces of the plant. The stoma
-functions as the chief channel for the passage of CO₂-laden air into
-the leaf and of oxygen-laden air from the leaf to the atmosphere. The
-stoma also functions as an organ of transpiration, since through the
-stoma a large part of the excess water of the plant passes off into
-the air.
-
-
-                             WATER-PORES
-
-In certain plants the primary epidermis is provided with openings
-resembling stomata, but unlike stomata the orifice remains open, and
-instead of being located on the upper or lower surface of the leaf,
-they are located on the margin of leaves immediately outward from the
-veins. Water is given off to the atmosphere from these openings. Such
-an opening is usually designated as a water-pore.
-
-
-                               STOMATA
-
-The chief external openings of the epidermis of leaves, of herbs, and
-of young wood stems are known as stomata. Surrounding the stoma are
-two cells known as guard cells.
-
-=Guard cells= differ greatly in form, in size, in arrangement, in
-occurrence, in association, in abundance (Plates 53, 54, and 55), and
-in color. The guard cells surrounding the stoma vary in form from
-circular to lens-shaped. In most leaves the outline of the guard
-cells is rounded or has a curved outline; but in a few cases the
-guard cells have angled outlines.
-
-[Illustration: PLATE 53
-
-  1. Stoma and surrounding cells of aconite stem (_Aconitum
-  napellus_, L.).
-
-  2. Stoma and angled striated walled surrounding cells of peppermint
-  stem (_Mentha piperita_, L.). 3. Stoma and elongated surrounding
-  cells of lobelia stem (_Lobelia inflata_, L.).]
-
-[Illustration: PLATE 54
-
-                           TYPES OF STOMA
-
-  1. Under epidermis of short buchu (_Barosma betulina_, [Berg.]
-  Bartling and Wendl., f.) showing stoma and deposits of hesperidin.
-
-  2. Under epidermis of Alexandria senna (_Cassia acutifolia_,
-  Delile) showing stoma and thick-angled walled surrounding cells.
-
-  3. Upper epidermis of eucalyptus leaf (_Eucalyptus globulus_,
-  Labill.) showing sunken stoma and slightly beaded walled
-  surrounding cells.
-
-  4. Under epidermis of belladonna leaf (_Atropa belladonna_, L.)
-  showing stoma and wavy, striated, walled epidermal cells.]
-
-The =arrangement of the surrounding cells= of the stoma is one of the
-most important characteristics of the different leaves. As a rule the
-number of surrounding cells about a stoma is constant for a given
-species. In senna leaves (Plate 54, Fig. 2) there are normally two
-surrounding cells about each guard cell, while in coca there are four
-(Plate 55, Fig. 1). In senna the long diameter of the surrounding
-cells is parallel to the long diameter of the guard cells; but in
-coca the long diameter of two surrounding cells is at right angles to
-the long diameter of the guard cells, while two cells are parallel to
-the long diameter of the guard cells.
-
-In most leaves there are more than two cells around the guard cells.
-
-The form and size of the surrounding cells must always be considered.
-In most leaves they are variable in size and form.
-
-Guard cells occur first, even with the surface of the leaf (Plate 56,
-Fig. A); secondly, above the surface of the leaf (Plate 56, Fig. B);
-and, thirdly, below the surface of the leaf. (Plate 56, Fig. C). Only
-one of the above types occurs in a given species of plant. That is,
-plants with stomata above the surface of the leaf do not have stomata
-on a level with or below the leaf surface.
-
-The number of stomata on a given surface of a different leaf varies
-considerably.
-
-In many of the medicinal leaves stomata occur only on the under
-surface of the leaf. In other leaves stomata occur on both surfaces
-of the leaf; but in such cases there are a greater number on the
-under surface.
-
-In certain leaves the long diameter of the guard cells is parallel to
-the length of the leaf; in other cases the long diameter of the stoma
-is arranged at right angles to the length of the leaf.
-
-In other leaves the arrangement is still more irregular, the guard
-cells assuming all sorts of positions in relation to the length of
-the leaf.
-
-[Illustration: PLATE 55
-
-                      LEAF EPIDERMI WITH STOMA
-
-  1. Under epidermis of coca leaf (_Erythroxylon coca_, Lam.) with
-  stoma on a level with the surface.
-
-  2. Under epidermis of false buchu (_Marrubium peregrinum_, L.) with
-  stoma below the level of the surface.
-
-  3. Upper epidermis of deer tongue (_Trilisa odoratissima_, [Walt.]
-  Cass.) with stoma above the leaf surface.]
-
-[Illustration: PLATE 56
-
-  _A._ Cross-section of belladonna leaf (_Atropa belladonna_, L.).
-  1, Epidermal cells; 2, Guard cells even with the leaf surface; 3,
-  Surrounding cells; 4, Air space below the guard cells; 5, Palisade
-  cells; 6, Mesophyll cells. _B._ Cross-section of deer tongue leaf,
-  1. Epidermal cells; 2, Guard cells above the surface of the leaf;
-  3, Surrounding cells; 4, Air space below the guard cells; 5,
-  Hypodermal cells. _C._ Cross-section of white pine leaf (_Pinus
-  strobus_, L.). 1, Epidermal and hypodermal cells; 2, Guard cells
-  below the leaf surface; 3, Surrounding cells; 4, Air space below
-  the guard cells; 5, Parenchyma cells with projecting inner walls.]
-
-The =relation of the stoma to surrounding cells= is best shown in
-cross-sections of the leaf. In powders the relationship of the stoma
-to the surrounding cells is, however, readily ascertained. If the
-guard cells come in focus first, they are above the surface; if the
-guard cells and the surrounding cells come in focus at the same time,
-the stomata are even with the surface; if the stomata come in focus
-after the surrounding cells, they are below the surface of the leaf.
-The relationship of the stoma to the surrounding cells should always
-be ascertained, not only in cross-sections of the leaf, but also in
-powders.
-
-There is the greatest possible variation in the size of guard cells.
-This fact must always be kept in mind when studying leaves. This
-variation in the size of the guard cells is clearly illustrated by
-coca, senna, and by deer’s-tongue. In coca the stomata are very
-small; in senna they are larger; while in deer’s-tongue the stomata
-are very large.
-
-The width and length of the stoma or opening between the guard cells
-are of a character which must not be overlooked. Generally speaking,
-those leaves which have large guard cells will have correspondingly
-large stomata.
-
-The guard cells usually contain chloroplasts showing various stages
-of decomposition.
-
-In bay-rum leaf the guard cells are of a bright reddish-brown color,
-but in most leaves the guard cells are colorless.
-
-
-                              LENTICELS
-
-=Lenticels= are small openings occurring in the bark of plants.
-The lenticels bear the same relationship to the stem that the
-stomata do to the leaves. Lenticels, like stomata, have a threefold
-function--namely, exchange of gases in photosynthesis, in
-respiration, and the giving off of water.
-
-Lenticels are macroscopically as well as microscopically important.
-When unmagnified the lenticels are circular, lens-shaped, or
-irregular in outline. They are arranged in parallel longitudinal
-lines or parallel transverse lines, or they are irregularly
-scattered. The latter is the usual arrangement. In most cases they
-are elevated slightly above the surface of the bark. In root barks
-particularly the lenticels stand out prominently from the surface of
-the bark and in many cases appear stalked.
-
-The color of the lenticels differs greatly in the different plants.
-In acer spicatium they are brown; in witch-hazel they are gray; in
-xanthoxylium they are yellowish; and lastly, the number of lenticels
-occurring in a given surface of the bark should always be considered.
-
-On cross-sections the lenticel (Plate 57, Fig. 2) is seen to have
-a central depressed portion made up of loosely arranged cells.
-Bordering the cavity are typical cork cells. The cork cells
-immediately surrounding the lenticels are usually darker in color,
-and many of the cells are partly broken down.
-
-The size of lenticels will vary according to the type of the
-lenticel. In studying sections more attention should be paid to the
-character of the cells forming the lenticels than to the size of the
-lenticel.
-
-On cross-section the intercellular spaces (Plate 58) are triangular,
-quadrangular, or irregular. The spaces between equal diameter
-parenchyma cells is triangular if three cells surround the space, and
-quadrangular if four cells surround the space, etc. These spaces are
-in direct contact with similar spaces that traverse the tissue at
-right angles to its long axis.
-
-The branched mesophyll cells of the leaf and aquatic plant parenchyma
-(Plate 59) are arranged around irregular cavities. In leaves and
-aquatic plants these spaces run parallel to the long axis of the
-organ.
-
-In each of the above cases the cavity is formed by the separation of
-the cell walls. There is still another type of irregular cavities
-which is formed by the dissolution or tearing apart of the cell
-walls. Such cavities are found in the stems and roots of many herbs.
-
-The pith cells in the stems of many herbs become torn apart during
-the growth of the stem, with the result that large irregular cavities
-are formed. These cavities are usually filled with circulatory air.
-
-In the stems of conium, cicuta, angelica, and other larger herbaceous
-stems the pith separates into layers. When a longitudinal section
-is made of such a stem it is seen to be composed of alternating air
-spaces and masses of pith parenchyma.
-
-The intercellular spaces are very large in leaves where enormous
-quantities of carbon dioxide are vitalized in photosynthesis.
-
-[Illustration: PLATE 57
-
-  CROSS-SECTION OF ELDER BARK (_Sambucus canadensis_, L.). 1.
-  Periderm. 2. Lenticel. 3. Phellogen.]
-
-[Illustration: PLATE 58
-
-                      INTERCELLULAR AIR SPACES
-
-  _A._ Cross-section of uva-ursi leaf (_Arctostaphylos uva-ursi_,
-  [L.] Spreng.).
-
-  1. Irregular intercellular air spaces.
-
-  _B._ Cross-section of the cortical parenchyma of sarsaparilla
-  root (_Smilax officinalis_, Kunth). 1, Triangular intercellular
-  spaces; 2, Quadrangular intercellular air spaces; 3, Pentagular
-  intercellular air spaces.]
-
-[Illustration: PLATE 59
-
-                 IRREGULAR INTERCELLULAR AIR SPACES
-
-  1. Skunk-cabbage (_Symplocarpus fœtidus_, [L.] Nutt.)
-  2. Calamus rhizome (_Acorus calamus_, L.).]
-
-In the rhizome of calamus and other aquatic plants the intercellular
-spaces are very large. The cells of these plants are arranged in
-the form of branching chains of cells which thus provide for large
-intercellular spaces.
-
-The cells of the middle layer of flower petals, like the mesophyll of
-leaves, is loosely arranged owing to the peculiar branching form of
-the cells.
-
-Seeds and fruits contain, as a rule, few or no intercellular spaces.
-
-
-
-
-                             CHAPTER VII
-
-                          SYNTHETIC TISSUE
-
-
-Under synthetic tissue are grouped all tissues and cells which form
-substances or compounds other than protoplasm. Such compounds are
-stored either in special cavities or in the cells of the plant, as
-the glandular hairs; internal secreting cavities of barks, stems,
-leaves, fruits, seeds, and flowers; photosynthetic cells or cells
-with chlorophyll, and the parenchymatic cells which form starch,
-sugar, fats, alkaloids, etc.
-
-
-                        PHOTOSYNTHETIC TISSUE
-
-The most important non-glandular synthetic tissue is the
-photosynthetic tissue, which is composed of the chlorophyll-bearing
-cells of the plant. These are the so-called green cells of leaves, of
-stems of herbs, of young woody stems, and in the older woody stems of
-plants like wild cherry, birch, etc. The greater part of the tissue
-of leaves is composed of chlorophyll-bearing cells.
-
-Leaves collectively constitute the greatest synthetic manufacturing
-plant in the world, because the green cells of the leaf produce most
-of the food of men and animals. The two compounds utilized in the
-manufacture of food are carbon dioxide (CO₂) and water (H₂O). These
-two compounds are combined by chlorophyll through the agency of light
-into starch. Chemically this reaction may be expressed as follows:
-
-                    6CO₂ + 5H₂O = 2C₆H₁₀O₅ + 6O₂.
-
-During the day a large quantity of starch is formed. At night through
-the action of a ferment the excess of starch remaining in the leaf
-is converted into sugar (C₆H₁₂O₆) - C₆H₁₀O₅ + H₂O = C₆H₁₂O₆. In this
-form it is distributed to the living cells of the plant. The presence
-or absence of starch in leaves is easily ascertained by placing the
-leaf in hot alcohol to remove the chlorophyll, and by adding Lugol’s
-solution. If starch is present, the contents of the cells will become
-bluish black; but if no starch is present, the cells remain colorless.
-
-
-                          GLANDULAR TISSUE
-
-The =glandular tissue= of the plant is divided into two groups,
-according to where it occurs. These groups are, first, =external=
-glandular tissue, and secondly, =internal= glandular tissue. The most
-important external glandular tissue is composed of the glandular
-hairs. These are divided into two groups: first, =unicellular=; and
-secondly, =multicellular= glandular hairs.
-
-
-                     UNICELLULAR GLANDULAR HAIRS
-
-The =unicellular glandular hairs= are either sessile or stalked.
-
-=Sessile unicellular hairs= occur in digitalis leaves.
-
-=Stalked unicellular hairs= of digitalis are shown on Plate 60, Fig.
-2.
-
-=Unicellular uniseriate stalked glandular hairs= occur on the stems
-of the common house geranium (Plate 61, Fig. 2), on the leaves of
-butternut, the leaves and stems of marrubium peregrinum (Plate 98,
-Fig. 5), and in arnica flowers. The stalk varies from two to ten
-cells; in eriodictyon the cells vary from four to eight cells.
-
-Unicellular multiseriate stalked glandular hairs are not of common
-occurrence.
-
-
-                    MULTICELLULAR GLANDULAR HAIRS
-
-=Multicellular glandular hairs= are divided into two groups: first,
-sessile; and secondly, stalked hairs.
-
-Multicellular sessile glandular hairs occur on the leaves of
-peppermint (Plate 60, Fig. 3), horehound (Plate 97, Fig. 7), and
-in hops (Plate 60, Fig. 4). In each of these hairs there are eight
-secretion cells.
-
-=Stalked glandular hairs= are divided into two groups: first,
-uniseriate stalked; and secondly, multiseriate stalked glandular
-hairs.
-
-=Multicellular uniseriate stalked glandular hairs= occur on the
-leaves of tobacco (Plate 61, Fig. 4), belladonna (Plate 61, Fig. 1),
-and digitalis (Plate 60, Fig. 2), and of the fruit of rhus glabra.
-
-[Illustration: PLATE 60
-
-                           GLANDULAR HAIRS
-
-  1. Kamala (_Mallotus philippinensis_, [Lam.] [Muell.] Arg.).
-  2. Digitalis leaf (_Digitalis purpurea_, L.).
-  3. Peppermint leaf (_Mentha piperita_, L.).
-  4. Lupulin.
-  5. Cannabis indica leaf (_Cannabis saliva_, L.).]
-
-=Multicellular multiseriate stalked glandular hairs= occur on the
-stems and leaves of cannabis indica (Plate 60, Fig. 5).
-
-In the glandular hair of kamala (Plate 60, Fig. 1) the number of
-secretion cells is variable and papillate in form, and the cuticle is
-separated from the secretion cells.
-
-In the glandular hair of hops the outer wall or cuticle is torn away
-from the secretion cells, and the cavity thus formed serves as a
-storage cavity. This distended cuticle of the hops shows the outline
-of the cells from which it was separated.
-
-In the glandular hairs of the mints the secreted products (volatile
-oils) are stored between the secretion cells and the outer detached
-cuticle. This cuticle is elastic, and it becomes greatly distended as
-the volatile oil increases in amount.
-
-In many of the so-called glandular hairs, tobacco, belladonna
-geranium, etc., the synthetic products are retained in the glandular
-cells, there being no special cavity for their storage.
-
-These hairs usually contain an abundance of chlorophyll.
-
-The division wall of multicellular glandular hairs may be vertical,
-as in the two-celled hair of digitalis (Plate 60, Fig. 2); as in
-horehound (Plate 97, Fig. 6), and as in peppermint (Plate 60, Fig.
-3); in this case there are eight cells, and they form a more or less
-flat plate of cells.
-
-In other hairs the division wall is horizontal; this produces a chain
-of superimposed secreting cells, as in some of the glandular hairs of
-belladonna leaf (Plate 61, Fig. 1), etc.
-
-In other hairs the division walls are both vertical and horizontal,
-as in tobacco (Plate 61, Fig. 4), henbane (Plate 61, Fig. 3),
-belladonna (Plate 61, Fig. 1).
-
-Other characters to be kept in mind in studying glandular hairs are
-the following: Color of cell contents; size of the cells, whether
-uniform or variable; character of wall, whether smooth or rough.
-
-
-                         SECRETION CAVITIES
-
-=Secretion cavities= are divided into three groups, according to the
-nature of the origin of the cavity: first, schizogenous cavities,
-which originate by a separation of the walls of the secretion cells;
-secondly, lysigenous cavities, which arise by the dissolution
-of the walls of centrally located secretion cells; and thirdly,
-schizo-lysigenous cavities, which originate schizogenously, but later
-become lysigenous owing to the dissolution of the outer layers of the
-secretion cells.
-
-[Illustration: PLATE 61
-
-                       STALKED GLANDULAR HAIRS
-
-  1. Belladonna leaf (_Atropa belladonna_, L.).
-  2. Geranium stem (_Geranium maculatum_, L.).
-  3. Henbane leaf (_Hyoscyamus niger_, L.).
-  4. Tobacco leaf (_Nicotiana tabacum_, L.).]
-
-
-                        SCHIZOGENOUS CAVITIES
-
-=Schizogenous cavities= occur in white pine bark (Plate 62, Fig.
-B). The cells lining the cavity are mostly tangentially elongated,
-and the wall extends into the cavity in the form of a papillate
-projection. Immediately back from these cells are two or three layers
-of cells which resemble cortical parenchyma cells, except that they
-are smaller and their walls are thinner.
-
-In white pine bark there is a single layer of thin-walled cells
-lining the cavity. Immediately surrounding the secretion cells is a
-single layer of thick-walled fibrous cells.
-
-In klip buchu (Plate 63, Fig. B), as in white pine leaf (Plate 64,
-Fig. B), there is a single layer of thin-walled secretion cells which
-are surrounded on three sides with parenchyma cells and on the outer
-side by epidermal cells.
-
-
-                         LYSIGENOUS CAVITIES
-
-=Lysigenous cavities= occur on the rind of citrus fruits--bitter and
-sweet orange, lemon, grapefruit, lime, etc., and in the leaves of
-garden rue, etc.
-
-In bitter orange peel, (Plate 64, Fig. A) the cavity is very
-large, and the cells bordering the cavity are broken and partially
-dissolved. The entire cells back of these are white, thin-walled,
-tangentially elongated cells. There is a great variation in the size
-of these cavities, the smaller cavities being the recently formed
-cavities.
-
-
-                     SCHIZO-LYSIGENOUS CAVITIES
-
-=Schizo-lysigenous= cavities are formed in white pine bark and many
-other plants owing to the increase in diameter of the stem. In such
-cases the walls of the secreting cells break down. The resulting
-cavity resembles lysigenous cavities.
-
-=Unicellular secretion cavities= occur in ginger, aloe, calamus, and
-in canella alba barb.
-
-[Illustration: PLATE 62
-
-  _A._ Cross-section of calamus rhizome (_Acorus calamus_, L.). 1,
-  Intercellular space; 2, Parenchyma cells; 3, Secretion cavity.
-  _B._ Cross-section of white pine bark (_Pinus strobus_, L.). 1,
-  Parenchyma; 2, Secretion cavity; 3, Secretion cells.]
-
-[Illustration: PLATE 63
-
-  _A._ Cross-section of a portion of canella alba bark (_Canella
-  alba_, Murr.). 1. Excretion cavity.
-  _B._ Cross-section of a portion of klip buchu leaf.
-    1. Epidermal cells.
-    2. Secretion cavity.
-    3. Secretion cells.]
-
-[Illustration: PLATE 64
-
-  _A._ Cross-section of bitter orange peel (_Citrus aurantium_,
-  _amara_, L.). 1, Internal secretion cavity formed by the
-  dissolution of the walls of the central secreting cells; 2,
-  Secretion cells. _B._ Cross-section of white pine leaf (_Pinus
-  strobus_, L.). 1, Epidermal and hypodermal cells; 2, Parenchyma
-  cells with protruding inner walls; 3, Endodermis; 4, Secretion
-  cavity; 5, Secretion cells.]
-
-In calamus (Plate 62, Fig. A) the cavity is larger than the
-surrounding cells; it is rounded in outline, and it contains
-oleoresin. These cavities are in contact with the ordinary parenchyma
-cells, from which they are easily distinguished by their larger size
-and rounded form.
-
-The =unicellular oil cavity= of canella alba (Plate 63, Fig. A) is
-rounded or oval in cross-section and is many times larger than the
-surrounding cells. The wall, which is very thick, is of a yellowish
-color.
-
-Secretion cavities vary greatly in form, according to the part of the
-plant in which they are found. In flower petals and leaves they are
-spherical; in barks they are usually elliptical; in umbelliferous
-fruits they are elongated and tube-like.
-
-Mucilage cavities are not of common occurrence in medicinal plants.
-They occur, however, in the stem and root bark of sassafras, the stem
-bark of slippery elm, the root of althea, etc.
-
-
-
-
-                            CHAPTER VIII
-
-                           STORAGE TISSUE
-
-
-Most drug plants contain storage products because they are
-collected at a period of the year when the plant is storing, or has
-stored, reserve products. These products are stored in a number of
-characteristic ways and in different types of tissue.
-
-The most important of the different types of storage tissue that
-occurs in plants are the storage cells, the storage cavities, and the
-storage walls.
-
-
-                            STORAGE CELLS
-
-Several different types of cells function as storage tissue. These
-cells, which are given in the order of their importance, are
-parenchyma, crystal cells, medullary rays, stone cells, wood fibres,
-bast fibres, and epidermal and hypodermal cells.
-
-
-                         CORTICAL PARENCHYMA
-
-=Cortical parenchyma= of biennial rhizomes, bulbs, roots, and the
-parenchyma of the endosperm of seeds store most of the reserve
-economic food products of the higher plants.
-
-=Pith parenchyma= of sarsaparilla root (Plate 65, Fig. 4) and
-the pith parenchyma of the rhizome of memspermun, like the pith
-parenchyma of most plants, function as storage cells.
-
-
-                           WOOD PARENCHYMA
-
-=Wood parenchyma=, particularly of the older wood, function as
-storage tissue. The wood parenchyma of quassia, like the wood
-parenchyma of most woods, contain stored products. In some cases the
-wood parenchyma contain starch, in others crystals, and in others
-coloring matter, etc.
-
-[Illustration: PLATE 65
-
-  1. Stone cells with starch of Ceylon cinnamon (_Cinnamomum
-  ceylanicum_, Nees.). 2. Stone cells with solitary crystals of
-  calumba root (_Jateorhiza palmata_, [Lam.] Miers). 3. Parenchyma
-  cells, with starch of cascarilla bark (_Croton eluteria_, [L.]
-  Benn.). 4. Cortical parenchyma with starch of sarsaparilla root
-  (_Smilax officinalis_, Kunth). 5. Cortical parenchyma, with
-  starch of leptandra rhizome (_Leptandra virginica_, [L.] Nutt.).
-  6. Crystal cells, with solitary crystals of quebracho bark
-  (Schlechtendal). 7. Bast fibre of blackberry root with starch
-  (_Rubus cuneifolius_, Pursh.).]
-
-[Illustration: PLATE 66
-
-                         MUCILAGE AND RESIN
-
-  1. Cross-section of elm bark (_Ulmus fulva_, Michaux) showing two
-  cavities filled with partially swollen mucilage.
-  2. Mucilage mass from sassafras stem bark (_Sassafras variifolium_,
-  L.).
-  3. Mucilage mass from elm bark.
-  4. Resin mass from white pine bark (_Pinus strobus_, L.).]
-
-In many plants, however, the parenchyma cells contain crystals. The
-parenchyma cells of rhubarb contain rosette crystals, while the
-parenchyma cells of the cortex of sarsaparilla and false unicorn root
-contain bundles of raphides. In every case observed the raphides are
-surrounded by mucilage. This is true of squills, sarsaparilla, false
-unicorn, etc. When cells with raphides and mucilage are mounted in a
-mixture of alcohol, glycerine, and water, the mucilage first swells
-and finally disappears.
-
-
-                          STORAGE CAVITIES
-
-Particular attention should be given to =storage cavities= whenever
-they occur in plants, for the reason that they are usually filled
-with storage products, and for the added reason that storage cavities
-are not common to all plants. Storage cavities occur in roots, stems,
-leaves, flowers, fruits, and seeds.
-
-
-                          CRYSTAL CAVITIES
-
-Characteristic =crystal cavities= occur in many plants. Such a cavity
-containing a bundle of raphides is shown in the cross-section of
-skunk cabbage leaf (Plate 67).
-
-
-                         SECRETION CAVITIES
-
-In white pine bark there are a great number of secretion cavities
-which are partially or completely filled with oleoresin. In the
-cross-sections of white pine bark the secretion cavities are very
-conspicuous, and they vary greatly in size. This variation is due,
-first, to the age of the cavity, the more recently formed cavities
-being smaller; and secondly, to the nature of the section, which will
-be longer in longitudinal section, which will be through the length
-of the secretion cavity, and shorter on transverse section. Such a
-section shows the width of the secretion cavity.
-
-Characteristic =mucilage cavities= occur in sassafras root, stem
-bark, elm bark (Plate 66, Fig. 1), marshmallow root, etc. These
-cavities form a conspicuous feature of the cross-section of these
-plants. The presence or absence of mucilage cavities in a bark should
-be carefully noted.
-
-
-                           LATEX CAVITIES
-
-The =latex tube cavities= are characteristic in the plants in which
-they occur. These cavities as explained under latex tubes are very
-irregular in outline.
-
-[Illustration: PLATE 67
-
-    CROSS-SECTION OF SKUNK-CABBAGE LEAF (_Symplocarpus fœtidus_,
-                             [L.] Nutt.)
-
-  1. Crystal cavity.
-  2. Bundle of raphides.]
-
-
-                             OIL CAVITY
-
-Canella alba contains an =oil cavity= resembling in form the mucilage
-cavity of elm bark.
-
-=Secretion cavities= occur in most of the umbelliferous fruits. For
-each fruit there is a more or less constant number of cavities. Anise
-has twenty or more, fennel usually has six cavities, and parsley has
-six cavities.
-
-In poison hemlock fruits there are no secretion cavities. In certain
-cases, however, the number of secretion cavities can be made to vary.
-This was proved by the author in the case of celery seed. He found
-that cultivated celery seed, from which stalks are grown, contains
-six oil cavities (Plate 122, Fig. 2), while wild celery seed (Plate
-102, Fig. 1), grown for its medicinal value, always contains more
-than six cavities. Most of the wild celery seeds contain twelve
-cavities.
-
-Many leaves contain cavities for storing secreted products. Such
-storage cavities occur in fragrant goldenrod, buchu, thyme, savary,
-etc.
-
-The leaves in which such cavities occur are designated as
-pellucid-punctate leaves. Such leaves will, when held between the eye
-and the source of light, exhibit numerous rounded translucent spots,
-or storage cavities.
-
-
-                           GLANDULAR HAIRS
-
-The =glandular hair of peppermint= (Plate 60, Fig. 3) and other mints
-consists of eight secretion cells, arranged around a central cavity
-and an outer wall which is free from the secretion cells. This outer
-wall becomes greatly distended when the secretion cells are active,
-and the space between the secretion cells and the wall serves as the
-storage place for the oil. When the mints are collected and dried,
-the oil remains in the storage cavity for a long time.
-
-
-                             STONE CELLS
-
-The =stone cells= of the different cinnamons (Plate 65, Fig. 1) store
-starch grains; these grains often completely fill the stone cells.
-
-The yellow stone cells of calumba root (Plate 65, Fig. 2) usually
-contain four prisms of calcium oxalate, which may be nearly uniform
-or very unequal in size.
-
-
-                             BAST FIBRES
-
-The =bast fibres= of the different rubus species (Plate 65, Fig. 7)
-contain starch. The medullary rays of quassia (Plate 107, Fig. 2)
-contain starch; while the medullary rays of canella alba contain
-rosette crystals. In a cross-section of canella alba (Plate 81, Fig.
-3) the crystals form parallel radiating lines which, upon closer
-examination, are seen to be medullary rays, in each cell of which a
-crystal usually occurs.
-
-The =epidermal and hypodermal cells of leaves= serve as water-storage
-tissue. These cells usually appear empty in a section.
-
-The barks of many plants--_i.e._, quebracho, witch-hazel,
-cascara, frangula, the leaves of senna and coca, and the root of
-licorice--contain numerous crystals. These crystals occur in special
-storage cells--=crystal cells= (Plate 65, Fig. 6)--which usually form
-a completely enveloping layer around the bast fibres. These cells are
-usually the smallest cells of the plant in which they occur, and with
-but few exceptions each cell contains but a single crystal.
-
-The epidermal cells of senna leaves and the epidermal cells of
-mustard are filled with mucilage; the walls even consist of mucilage.
-Such cells are always diagnostic in powders.
-
-
-                            STORAGE WALLS
-
-=Storage walls= (Plates 68 and 69) occur in colchicum seed, saw
-palmetto seed, areca nut, nux vomica, and Saint Ignatius’s bean. In
-each of these seeds the walls are strongly and characteristically
-thickened and pitted. In no two plants are they alike, and in each
-plant they are important diagnostic characters.
-
-Storage cell walls consist of reserve cellulose, a form of cellulose
-which is rendered soluble by ferments, and utilized as food during
-the growth of the seed. Reserve cellulose is hard, bony, and of a
-waxy lustre when dry. Upon boiling in water the walls swell and
-become soft.
-
-The structure of the reserve cellulose varies greatly in the
-different seeds in which it occurs in the thickness of the walls and
-in the number and character of the pores.
-
-[Illustration: PLATE 68
-
-                          RESERVE CELLULOSE
-
-  1. Saw palmetto (_Serenoa serrulata_, [Michaux] Hook., f.).
-  2. Areca nut (_Areca catechu_, L.).
-  3. Colchicum seed (_Colchicum autumnale_, L.).
-  3-_A_. Porous side wall.
-  3-_B_. Cell cavity above the side wall.]
-
-[Illustration: PLATE 69
-
-                          RESERVE CELLULOSE
-
-  1. Endosperm of nux vomica (_Strychnos nux vomica_, L.).
-  2. Endosperm of St. Ignatia bean (_Strychnos ignatii_, Berg.).]
-
-
-
-
-                             CHAPTER IX
-
-                            CELL CONTENTS
-
-
-The cell contents of the plant are divided into two groups: first,
-organic cell contents; and secondly, inorganic cell contents.
-
-The =organic= cell contents include plastids, starch grains,
-mucilage, inulin, sugar, hesperidin, alkaloids, glucocides, tannin,
-resin, and oils.
-
-
-                             CHLOROPHYLL
-
-The =chloroplasts= of the higher plants are green, and they vary
-somewhat in size, but they have a similar structure and form.
-
-Chloroplasts are mostly oval in longitudinal view and rounded in
-cross-section view. Each chlorophyll grain has an extremely thin
-outer wall, which encloses the protoplasmic substance, the green
-granules, a green pigment (chlorophyll), and a yellow pigment
-(xanthophyll). Frequently the wall includes starch, oil drops, and
-protein crystals.
-
-Chloroplasts are arranged either in a regular peripheral manner along
-the walls, or they are diffused throughout the protoplast.
-
-The palisade cells of most leaves are packed with chlorophyll grains.
-In the mesophyll cells the chlorophyll grains are not so numerous,
-and they are arranged peripherally around the innermost part of the
-wall.
-
-Chloroplasts multiply by fission--that is, each chloroplast divides
-into two equal halves, each of which develops into a normal
-chloroplast.
-
-Chlorophyll occurs in the palisade, spongy parenchyma, and guard
-cells of the leaf; in the collenchyma and parenchyma of the cortex
-of the stems of herbs and of young woody stems, and, under certain
-conditions, in rhizomes and roots exposed to light. Almost without
-exception young seeds and fruits have chlorophyll.
-
-In powdered leaves, stems, etc., the chlorophyll grains occur in the
-cells as greenish, more or less structureless masses. Yet cells with
-chlorophyll are readily distinguished from cells with other cell
-contents. In witch-hazel leaf the chlorophyll grains appear brownish
-in color. Powdered leaves and herbs are readily distinguished from
-bark, wood, root, and flower powders.
-
-Leaves and the stems of herbs are of a bright-green color. With the
-exception of the guard cells, the chloroplasts occur one or more
-layers below the epidermis; but, owing to the translucent nature of
-the outer walls of these cells, the outer cells of leaves and stems
-appear green.
-
-Wild cherry, sweet birch, and, in fact, most trees with smooth barks
-have =chloroplasts= in several of the outer layers of the cortical
-parenchyma. When the thin outer bark is removed from these plants,
-the underlying layers are seen to be of a bright-green color.
-
-
-                            LEUCOPLASTIDS
-
-=Leucoplastids=, or colorless plastids, occur in the underground
-portions of the plant; they may, when these organs in which they
-occur are exposed to light, change to chloroplastids.
-
-Leucoplasts are the builders of starch grains. They take the chemical
-substance starch and build or mould it into starch grains, storage
-starch, or reserve starch.
-
-Other characteristic chromoplasts found in plants are yellow and
-red. Yellow chromoplasts occur in carrot root and nasturtium flower
-petals. Red plastids occur in the ripe fruit of capsicum.
-
-
-                            STARCH GRAINS
-
-The chemical substance starch (C₆H₁₀O₅) is formed in chloroplasts.
-The starch thus formed is removed from the chloroplasts to other
-parts of the plant because it is the function of the chloroplasts to
-manufacture and not to store starch.
-
-The starch formed by the chloroplasts is acted upon by a ferment
-which adds one molecule of water to C₆H₁₀O₅, thus forming sugar
-C₆H₁₂O₆. This sugar is readily soluble in the cell sap, and is
-conducted to all parts of the plant. The sugar not utilized in cell
-metabolism is stored away in the form of reserve starch or starch
-grains by colorless plastids or amyloplasts.
-
-The amyloplasts change the sugar into starch by extracting a molecule
-of water. This structureless material (starch) is then formed by the
-amyloplast into starch grains having a definite and characteristic
-form and structure.
-
-Starch grams vary greatly in different species of plants, owing
-probably to the variation of the chemical composition, density, etc.,
-of the protoplast, and to the environmental conditions under which
-the plant is growing.
-
-
-                             OCCURRENCE
-
-Starch grains are simple, compound, or aggregate. =Simple starch=
-grains may occur as isolated grains (Plates 70, 71, and 72), or they
-may be associated as in cardamon seed, white pepper, cubeb, and
-grains of paradise, where the simple grains stick together in masses,
-having the outline of the cells in which they occur. These masses are
-known as aggregate starch.
-
-=Aggregate starch= (Plate 76) varies greatly in size, form, and in
-the nature of the starch grains forming the aggregations.
-
-=Compound starch grains= may be composed of two or more parts, and
-they are designated as 2, 3, 4, 5, etc., compound (Plate 75).
-
-The parts of a compound grain may be of equal size (Plate 75, Fig.
-4), or they may be of unequal size (Plate 75, Fig. 2).
-
-In most powders large numbers of the parts of the compound grains
-become separated. The part in contact with other grains shows plane
-surfaces, while the external part of the grain has a curved surface.
-There will be one plane and one curved surface if the grain is a half
-of a two-compound grain; two plane and one curved surface if the
-grain is a part of a three-compound grain, etc.
-
-The simple starch grains forming the aggregations become separated
-during the milling process and occur singly, so that in the drugs
-cited above the starch grains are solitary and aggregate.
-
-Many plants contain both simple and compound starch grains (Plate 74,
-Fig. 3).
-
-In some forms--_e.g._, belladonna root (Plate 75, Fig. 2) the
-compound grains are more numerous; while in sanguinaria the simple
-grains are more numerous, etc.
-
-
-                               OUTLINE
-
-The =outline= of starch grains is made up of (1) rounded, (2) angled,
-and (3) rounded and angled surfaces.
-
-Starch grains with rounded surfaces may be either spherical, as in
-Plate 74, Fig. 3, or oblong or elongated, as in Plate 71, Fig. 1.
-
-Other starches with rounded surfaces are shown on Plates 72 and 73.
-
-Angled outlined grains are common to cardamon seed, white pepper,
-cubebs, grains of paradise (Plate 76, Fig. 4), and to corn (Plate 70,
-Fig. 3).
-
-The outlines of all compound grains are made up partly of plane and
-partly of curved surfaces.
-
-
-                                SIZE
-
-The =size= (greatest diameter) of starch varies greatly even in the
-same species, but for each plant there is a normal variation.
-
-In spherical starch grains the size of the individual grains is
-invariable, but in elongated starch grains and in parts of compound
-grains the size will vary according to the part of the grain
-measured. In zedoary starch (Plate 71, Fig. 4), for instance, the
-size will vary according to whether the end, side, or surface of the
-starch grain is in focus.
-
-The parts of compound grains often vary greatly in size. Such a
-variation is shown in Plate 75, Fig. 2.
-
-
-                                HILUM
-
-The =hilum= is the starting-point of the starch grain or the first
-part of the grain laid down by the amyloplast. The hilum will be
-central if formed in the middle of the amyloplast, and excentral if
-formed near the surface of the amyloplast. It has been shown that the
-developing starch grain with eccentric hilum usually extends the wall
-of the amyloplast if it does not actually break through the wall.
-Starch grains with excentral hilums are therefore longer than broad.
-
-[Illustration: PLATE 70
-
-                               STARCH
-
-  1. Calabar bean (_Physostigma venenosum_, Balfour).
-  2. Marshmallow root (_Althæa officinalis_, L.).
-  3. Field corn (_Zea mays_, L.).]
-
-[Illustration: PLATE 71
-
-                               STARCH
-
-  1. Galanga root (_Alpinia officinarum_, Hance). 2. Kola nut (_Cola
-  vera_, [K.] Schum.). 3. Geranium rhizome (_Geranium maculatum_ L.).
-  4. Zedoary root (_Curcuma zedoaria_, Rosc.). 4-_A_. Surface view of
-  starch grain. 4-_B_. Side view of starch grain. 4-_C_. End view of
-  starch grain.]
-
-In central hilum starch grains the grain is laid down around the
-hilum in the form of concentric layers. These layers are of variable
-density. The dense layers are formed when plenty of sugar is
-available, and the less dense layers are formed when little sugar
-is available. The unequal density of the different layers gives the
-striated appearance characteristic of so many starch grains.
-
-In eccentric hilum starch grains the starch will be deposited in
-layers which are outside of and successively farther from the hilum.
-
-The term _hilum_ has come to have a broader meaning than formerly.
-Hilum includes at the present time not only the starting-point of the
-starch grain, but the fissures which form in the grain upon drying.
-In all cases these fissures originate in the starting-point, hilum,
-and in some cases extend for some distance from it. The hilum, when
-excentral, may occur in the broad end of the grain, galanga, and
-geranium (Plate 71, Figs, 1 and 3), or in the narrow end of the
-grain, zedoary (Plate 71, Fig. 4).
-
-
-                         NATURE OF THE HILUM
-
-The hilum, whether central or excentral, may be rounded (Plate 75,
-Fig. 1); or simple cleft, which may be straight (Plate 71, Fig. 1);
-or curved cleft (Plate 71, Fig. 2); or the hilum may be a multiple
-cleft (Plate 74, Fig. 3).
-
-In studying starches use cold water as the mounting medium, because
-in cold water the form and structure are best shown, and because
-there is no chemical action on the starch. On the other hand, the
-form and structure will vary considerably if the starch is mounted
-in hot water or in solutions of alkalies or acids. The hilum appears
-colorless when in sharp focus, and black when out of focus.
-
-Starch grains, when boiled with water, swell up and finally
-disintegrate to form starch paste.
-
-Starch paste turns blue upon the addition of a few drops of weak
-Lugol solution. Upon heating, this blue solution is decolorized, but
-the color reappears upon cooling. If a strong solution of Lugol is
-used in testing, the color will be bluish black.
-
-[Illustration: PLATE 72
-
-                               STARCH
-
-  1. Orris root (_Iris florentinia_ L.).
-  2. Stillingia root (_Stillingia sylvatica_, L.).
-  3. Calumba root (_Jateorhiza palmata_, [Lam.] Miers.).]
-
-[Illustration: PLATE 73
-
-                               STARCH
-
-  1. Male fern (_Dryopteris marginalis_, [L.] A. Gray).
-  2. African ginger (_Zingiber officinalis_, Rosc.).
-  3. Yellow dock (_Rumex crispus_, L.).
-  4. Pleurisy root (_Asclepias tuberosa_, L.).]
-
-[Illustration: PLATE 74
-
-                               STARCH
-
-  1. Kava-kava (_Piper methysticum_, Forst., f.).
-  2. Pokeroot (_Phytolacca americana_, L.).
-  3. Rhubarb (_Rheum officinale_, Baill.).]
-
-[Illustration: PLATE 75
-
-                            STARCH GRAINS
-
-  1. Bryonia (_Bryonia alba_, L.).
-  2. Belladonna root (_Atropa belladonna_, L.).
-  3. Valerian root (_Valeriana officinalis_, L.).
-  4. Colchicum root (_Colchicum autumnale_, L.).]
-
-[Illustration: PLATE 76
-
-                            STARCH MASSES
-
-  1. Aggregate starch of cardamon seed (_Elettaria cardamomum_,
-  Maton).
-  2. Aggregate starch of white pepper (_Piper nigrum_, L.).
-  3. Aggregate starch of cubebs (_Piper cubeba_, L., f.).
-  4. Aggregate starch of grains of paradise (_Amomum melegueta_,
-  Rosc.).]
-
-
-                               INULIN
-
-=Inulin= is the reserve carbohydrate material found in the plants of
-the composite family.
-
-The medicinal plants containing inulin are dandelion, chicory,
-elecampane, pyrethrum, and burdock. Plate 77, Figs, 1 and 2 show
-masses of inulin in dandelion and pyrethrum.
-
-In these plants the inulin occurs in the form of irregular,
-structureless, grayish-white masses (Plate 77). In powdered drugs
-inulin occurs either in the parenchyma cell or as irregular isolated
-fragments of variable size and form. Inulin is structureless and the
-inulin from one plant cannot be distinguished microscopically from
-the inulin of another plant. For this reason inulin has little or no
-diagnostic value. The presence or absence of inulin should always be
-noted, however, in examining powdered drugs, because only a few drugs
-contain inulin.
-
-When cold water is added to a powder containing inulin it dissolves.
-Solution will take place more quickly, however, in hot water.
-Inulin occurs in the living plant in the form of cell sap. If fresh
-sections of the plant are placed in alcohol or glycerine, the inulin
-precipitates in the form of crystals.
-
-
-                              MUCILAGE
-
-=Mucilage= is of common occurrence in medicinal plants.
-Characteristic mucilage cavities filled with mucilage occur in
-sassafras stem (Plate 66, Fig. 2), in elm bark (Plate 66, Fig. 1), in
-althea root, in the outer layer of mustard seed, and in the stem of
-cactus grandiflorus. In addition, mucilage is found associated with
-raphides in the crystal cells of sarsaparilla, squill, false unicorn,
-and polygonatum.
-
-When drugs containing mucilage are added to alcohol, glycerine, and
-water mixture, the mucilage swells slightly and becomes distinctly
-striated, but it will not dissolve for a long time. Refer to Plate
-79, Fig. 6.
-
-Mucilage, when associated with raphides, swells and rapidly dissolves
-when added to alcohol, glycerine, and water mixture. The mucilage is,
-therefore, different from the mucilage found in mucilage cavities,
-because it is more readily soluble.
-
-[Illustration: PLATE 77
-
-                    INULIN (_Inula helenium_, L.)
-
-  1. Inulin in the parenchyma cells of dandelion root.
-  2. Inulin from Roman pyrethrum root (_Anacyclus pyrethrum_, [L.] D.
-  C.). ]
-
-In coarse-powdered bark and other mucilage containing drugs the
-mucilage masses are mostly spherical or oval in outline (Plate 66,
-Figs. 2 and 3) the form being similar to the cavity in which the mass
-occurs.
-
-Acacia, tragacanth, and India gum consist of the dried mucilaginous
-excretions.
-
-
-                             HESPERIDIN
-
-=Hesperidin= occurs in the epidermal cells of short and long buchu.
-It is particularly characteristic in the epidermal cells of the dried
-leaves of short buchu. In these leaves the hesperidin occurs in
-masses which resemble rosette crystals (Plate 54, Fig. 1).
-
-Hesperidin is insoluble in glycerine, alcohol, and water, but it
-dissolves in alkali hydroxides, forming a yellowish solution.
-
-
-                            VOLATILE OILS
-
-=Volatile oils= occur in cinnamon stem bark, sassafras root bark,
-flowers of cloves, and in the fruits of allspice, anise, fennel,
-caraway, coriander, and cumin.
-
-In none of these cases is the volatile oil diagnostic, but its
-presence must always be determined.
-
-When a powdered drug containing a volatile oil is placed in alcohol,
-glycerine, and water mixture the volatile oil contained in the
-tissues will accumulate at the broken end of the cells in the form of
-rounded globules, while the volatile oil adhering to the surface of
-the fragments will dissolve in the mixture and float in the solution
-near the under side of the cover glass. Volatile oil is of little
-importance in histological work.
-
-
-                               TANNIN
-
-=Tannin= masses are usually red or reddish brown. Tannin occurs in
-cork cells, medullary rays of white pine bark (Plate 48, Fig. B),
-stone cells, and in special tannin sacs.
-
-The stone cells of hemlock and tamarac bark and the medullary rays of
-white pine and hemlock bark contain tannin.
-
-Tannin associated with prisms occurs in tannin sacs in white pine and
-tamarac bark. These sacs are frequently several millimeters in length
-and contain a great number of crystals surrounded by tannin.
-
-Deposits of tannin are colored bluish black with a solution of ferric
-chloride.
-
-
-                           ALEURONE GRAINS
-
-=Aleurone grains= are small granules of variable structure, size,
-and form, and they are composed of reserve proteins. They occur in
-celery, fennel, coriander, and anise, fruits, in sesame, sunflower,
-curcas, castor oil, croton oil, bitter almond, and other oil seeds.
-
-In many of the seeds the aleurone grains completely fill the cells of
-the endosperm, embryo, and perisperm. In wheat, rye, barley, oats,
-and corn the aleurone grains occur only in the outer layer or layers
-of the endosperm, the remaining layers in these cases being filled
-with starch.
-
-In powdered drugs the aleurone grains occur in parenchyma cells or
-free in the field.
-
-
-                    STRUCTURE OF ALEURONE GRAINS
-
-Aleurone grains are very variable in structure. The simplest grains
-consist of an undifferentiated mass of proteid substance surrounded
-by a thin outer membrane. In other grains the proteid substance
-encloses one or more rounded denser proteid bodies known as globoids.
-In other grains a crystalloid--crystal-like proteid substance--is
-present in addition to the globoid. In some grains are crystals
-of calcium oxalate, which may occur as prisms or as rosettes. All
-the different parts, however, do not occur in any one grain. In
-castor-oil seed (Plate 77_a_, Fig. 8) are shown the membrane (_A_),
-the ground mass (_B_), the crystalloid (_C_), and the globoid (_D_).
-
-
-                       FORM OF ALEURONE GRAINS
-
-Much attention has been given to the study of the special parts
-of the aleurone grains, but one of the most important diagnostic
-characters has been overlooked, namely, that of comparative form. For
-the purposes of comparing the forms of different grains, they should
-be mounted in a medium in which the grain and its various parts are
-insoluble. Oil of cedar is such a medium. The variation in form and
-size of the aleurone grains when mounted in oil of cedar is shown in
-Plate 77_a_.
-
-
-                   DESCRIPTION OF ALEURONE GRAINS
-
-The aleurone grains of curcas (Plate 77_a_, Fig. 1) vary in form
-from circular to lens-shaped, and each grain contains one or more
-globoids. The globoids are larger when they occur singly. In
-sunflower seed (Plate 77_a_, Fig. 2) the grains vary from reniform to
-oval, and one or more globoids are present; many occur in the center
-of the grain.
-
-The aleurone grains of flaxseed (Plate 77_a_, Fig. 3) resemble in
-form those of sunflower seed, but the grains are uniformly larger and
-some of the grains contain as many as five globoids.
-
-In bitter almond (Plate 77_a_, Fig. 4) the aleurone grains are mostly
-circular, but a few are nearly lens-shaped. A few of the large,
-rounded grains contain as many as nine globoids; in such cases one
-of the globoids is likely to be larger than the others. The aleurone
-grains of croton-oil seed (Plate 77_a_, Fig. 5) are circular in
-outline, variable in form, and each grain contains from one to seven
-globoids.
-
-In sesame seed (Plate 77_a_, Fig. 6) the typical grain is angled in
-outline and the large globoid occurs in the narrow or constricted end.
-
-The aleurone grains of castor-oil seed (Plate 77_a_, Fig. 7) resemble
-those of sesame seed, but they are much larger, and many of the
-grains contain three large globoids. When these grains are mounted in
-sodium-phosphate solution, the crystalloid becomes visible.
-
-
-                      TESTS FOR ALEURONE GRAINS
-
-Aleurone grains are colored yellow with nitric acid and red with
-Millon’s reagent.
-
-The proteid substance of the mass of the grain, of the globoid, and
-of the crystalloid, reacts differently with different reagents and
-dyes.
-
-The ground substance and the crystalloids are soluble in dilute
-alkali, while the globoids are insoluble in dilute alkali.
-
-The ground substance and crystalloids are soluble in sodium
-phosphate, while the globoids are insoluble in sodium phosphate.
-
-Calcium oxalate is insoluble in alkali and acetic acid, but it
-dissolves in hydrochloric acid.
-
-[Illustration: PLATE 77_a_
-
-                           ALEURONE GRAINS
-
-  1. Curcas (_Jatropha curcas_, L.).
-  2. Sunflower seed (_Helianthus annuus_, L.).
-  3. Flaxseed (_Linum usitatissimum_, L.).
-  4. Bitter almond (_Prunus amygdalus_, _amara_, D.C.).
-  5. Croton-oil seed (_Croton tiglium_, L.).
-  6. Sesame seed (_Sesamum indicum_, L.).
-  7 and 8. Castor-oil seed (_Ricinus communis_, L.).]
-
-
-                              CRYSTALS
-
-Calcium oxalate crystals form one of the most important inorganic
-cell contents found in plants, because of the permanency of the
-crystals, and because the forms common to a given species are
-invariable. By means of calcium oxalate crystals it is possible to
-distinguish between different species. In butternut root bark, for
-instance, only rosette crystals are found, while in black walnut
-root bark--a common substitute for butternut bark--both prisms and
-rosettes occur. This is only one of the many examples which could be
-cited.
-
-These crystals, for purposes of study, will be grouped into four
-principal classes, depending upon form and not upon crystal system.
-These classes are micro-crystals, raphides, rosettes, and solitary
-crystals.
-
-
-                           MICRO-CRYSTALS
-
-=Micro-crystals= are the smallest of all the crystals. Under the
-high power of the microscope they appear as a V, a Y, an X, and as
-a T. They are, therefore, three- or four-angled (Plate 78). The
-thicker portions of these crystals are the parts usually seen, but
-when a close observation of the crystals is made the thin portions
-of the crystal connecting the thicker parts may also be observed.
-Micro-crystals should be studied with the diaphragm of the microscope
-nearly closed and with the high-power objective in position. While
-observing the micro-crystals, raise and lower the objective by the
-fine adjustment in order to bring out the structure of the crystal
-more clearly. Micro-crystals occur in parenchyma cells of belladonna,
-scopola, stramonium, and bittersweet leaves; in belladonna, in
-horse-nettle root, in scopola rhizome, in bittersweet stems, and in
-yellow and red cinchona bark, etc.
-
-The crystals in each of the above parts of the plant are similar in
-form, the only observed variation being that of size. Their presence
-or absence should always be noted when studying powders.
-
-
-                              RAPHIDES
-
-=Raphides=, which are usually seen in longitudinal view, resemble
-double-pointed needles. They are circular in cross-section, and the
-largest diameter is at the centre, from which they taper gradually
-toward either end to a sharp point.
-
-[Illustration: PLATE 78
-
-                           MICRO-CRYSTALS
-
-  1. Horse-nettle root (_Solanum carolinense_, L.).
-  2. Scopola rhizome (_Scopolia carniolica_, Jacq.).
-  3. Belladonna root (_Atropa belladonna_, L.).
-  4. Bittersweet stem (_Solanum dulcamara_, L.).
-  5. Scopola leaf (_Scopola carniolica_, Jacq.).
-  6. Tobacco leaf (_Nicotiana tabacum_, L.).
-  7. Belladonna leaf (_Atropa belladonna_, L.).]
-
-Raphides occur in bundles, as in false unicorn root (Plate 79, Figs.
-6, A, B, and C), rarely as solitary crystals.
-
-In ipecac root the crystals are usually solitary. In sarsaparilla
-root, squill, etc., the raphides occur both in clusters, part of
-bundle, or in bundles, and as solitary crystals.
-
-In most drugs the crystals are entire; but in squills, where the
-raphides are very large, they are broken. In phytolacca (Plate 79,
-Fig. 1) and in hydrangea the raphides are usually broken, owing to
-the fact that these drugs contain large quantities of fibres which
-break them up into fragments when the drug is milled.
-
-There is the greatest possible variation in the size of raphides in
-the same and in different drugs, but the larger forms are constant in
-the same species.
-
-Raphides are deposited in parenchyma cells and in special raphides
-sacs. These crystals are always surrounded with mucilage.
-
-
-                          ROSETTE CRYSTALS
-
-=Rosette crystals= are compound crystals composed of an aggregation
-of small crystals arranged in a radiating manner around a central
-core. This core appears nearly black, and the whole mass is nearly
-spherical. The free ends of the crystals are sharp-pointed or blunt.
-
-Characteristic rosette crystals occur in frangula bark, spikenard
-root, wahoo stem, root bark, rhubarb, etc. (Plate 80, Figs. 1, 2, 3,
-4, 5, and 6).
-
-These crystals are very variable in size. This variation is
-illustrated by the crystals of Plate 80.
-
-Usually there is a variation in size of the crystals occurring in
-a given plant, but for each plant there is a more or less uniform
-variation. For instance, the largest rosette crystal occurring in
-wahoo root bark (Plate 80, Fig. 5) is smaller than the largest
-crystal occurring in rhubarb (Plate 80, Fig. 6), etc.
-
-[Illustration: PLATE 79
-
-                              RAPHIDES
-
-  1. Phytolacca root (_Phytolacca americana_, L.). 2. Squills
-  (_Urginea maritima_ [L.] Baker). 3. Hydrangea root (_Hydrangea
-  arborescens_, L.). 4. Convallaria (_Convallaria majalis_, L.).
-  5. Carthagean ipecac (_Cephælis acuminata_ Karst.) 6. Bundle of
-  raphides from false unicorn root.
-
-  _A._ Bundle surrounded with mucilage. _B._ Mucilage expanded and
-  partially dissolved. _C._ Bundle free of mucilage.]
-
-[Illustration: PLATE 80
-
-                          ROSETTE CRYSTALS
-
-  1. Frangula bark (_Rhamnus frangula_, L.).
-  2. White oak bark (_Quercus alba_, L.).
-  3. Spikenard root (_Aralia racemosa_, L.).
-  4. Wahoo stem bark (_Euonymus atropurpureus_, Jacq.).
-  5. Wahoo root bark (_Euonymus atropurpureus_, Jacq.).
-  6. Rhubarb (_Rheum officinale_, Baill.).]
-
-The prisms forming the rosette crystals, like all prisms, decompose
-white light, with the result that rosette crystals frequently appear
-variously colored. Rhubarb crystals, for instance, are blue or
-violet. Most of the smaller rosette crystals, however, appear grayish
-white with a darker-colored centre.
-
-Rosette crystals occur in parenchyma cells (Plate 81, Fig. 4) and in
-medullary rays (Plate 81, Fig. 3).
-
-
-                          SOLITARY CRYSTALS
-
-=Solitary crystals= are the most variable of all the forms of calcium
-oxalate. They usually occur in crystal cells associated with bast
-fibres and stone cells, less frequently in stone cells (Plate 33,
-Fig. 2). There are many different and characteristic forms of prisms.
-The more common are:
-
-  1. Rectangular:
-     A. Parallelepipeds.
-     B. Cubes.
-  2. Polyhedrons:
-     A. Irregular polyhedrons.
-         I. Flat bases.
-            (_a_) Non-notched.
-            (_b_) Notched.
-        II. Tapering bases.
-     B. Octohedrons.
-
-The crystals occurring in Batavia cinnamon and henbane leaves are
-parallelopipeds (Plate 82, Figs. 1 and 2).
-
-The crystals occurring in cactus grandiflorus, hemlock bark, krameria
-root, and soap bark are irregular polyhedrons (Plate 83). They
-are longer than broad, and the ends are tapering. The crystal of
-cactus grandiflorus has the narrowest diameter of these four, while
-the crystals of soap bark have the widest diameter. In coca leaf,
-xanthoxylum bark, elm bark, Spanish licorice, and in white oak (Plate
-84), and in cocillina bark (Plate 82, Fig. 4) the crystals are all
-irregular polyhedrons with flat bases. They are mostly longer than
-broad and they are all widest in the centre; in each a few crystals
-are notched, but most of the crystals are not notched.
-
-The crystals in quassia wood, uva-ursi leaf, and most of those of
-quebracho and wild cherry bark (Plate 86, Figs. 1, 2, 3, and 4) are
-irregular polyhedrons with flat ends. They are longer than broad,
-widest at the centre, and non-notched.
-
-[Illustration: PLATE 81
-
-                      INCLOSED ROSETTE CRYSTALS
-
-  1. Hops (_Humulus lupulus_, L.).
-  2. Bracts of cannabis indica (_Cannabis sativa_, variety _Indica_,
-  Lamarck).
-  3. Medullary rays of canella alba.
-  4. Parenchyma cells of mandrake (_Podophyllum peltatum_, L.).]
-
-[Illustration: PLATE 82
-
-                          SOLITARY CRYSTAL
-
-  1. Batavia cinnamon (_Cinnamomum burmanni_, Nees).
-  2. Henbane leaves (_Hyoscyamus niger_, L.).
-  3. Morea nutgalls.
-  4. Cocillana bark (_Guarea rusbyi_ [Britton], Rusby).]
-
-[Illustration: PLATE 83
-
-                          SOLITARY CRYSTALS
-
-  1. Cactus grandiflorus (_Cereus grandiflorus_ [L.], Britton and
-  Rose).
-  2. Hemlock bark (_Tsuga canadensis_ [L.], Carr.).
-  3. Krameria root (_Krameria triandra_, Ruiz and Pav.).
-  4. Soapbark (_Quillaja saponaria_, Molina).]
-
-[Illustration: PLATE 84
-
-                          SOLITARY CRYSTALS
-
-  1. Coca leaf (_Erythroxylon coca_, Lamarck).
-  2. Xanthoxylum bark (_Zanthoxylum americanum_, Miller).
-  3. Elm bark (_Ulmus fulva_, Michaux).
-  4. Spanish licorice root (_Glycyrrhiza glabra_, L.).
-  5. White oak bark (_Quercus alba_, L.).]
-
-Cubes occur in senna, cascara sagrada, frangula, white pine, tamarac
-(Plate 85), quassia, uva-ursi, quebracho, and in wild cherry (Plate
-86).
-
-The crystals of morea nutgalls (Plate 82, Fig. 3) are octahedrons,
-and they resemble the crystals of calcium oxalate found in urinary
-sediments.
-
-While studying the prisms, focus first on the upper surface and then
-down to the under surface in order to observe the forms accurately.
-
-There are several plants in which more than one form of crystal
-occur. Rosette crystals and prisms are associated, for instance, in
-cascara sagrada, frangula, condurango, dogwood, and pleurisy root
-(Plate 87, Figs. 1, 2, 3, 4, and 5).
-
-An important factor to be kept in mind in studying crystals is the
-number--whether abundant, as in rhubarb, or sparingly present, as in
-mandrake, etc. Variation in the number of crystals is not uncommon,
-even in different parts of the same plants. In wahoo stem bark, for
-instance, there are several times as many rosette crystals as there
-are in the root bark.
-
-Crystals of calcium oxalate are freely soluble in dilute hydrochloric
-acid without effervescence; but they are insoluble in acetic acid and
-in sodium and potassium hydroxide solutions. With sulphuric acid they
-form crystals of calcium sulphate.
-
-
-                             CYSTOLITHS
-
-=Cystoliths= consist of calcium carbonate deposited over and around a
-framework of cellulose.
-
-
-                         FORMS OF CYSTOLITHS
-
-The =forms of cystoliths= differ greatly in the different plants in
-which they occur.
-
-In the rubber-plant leaf, the cystolith resembles a bunch of grapes
-and is stalked; in ruellia root (Plate 87, Fig. 1) the cystoliths
-vary from nearly circular to narrowly cylindrical, and no stalk is
-present; also the cystolith nearly fills the cell in which it occurs.
-In the hair of cannabis indica (Plate 88, Fig. 3), the cystolith
-varies in form according to the size and shape of the hair, but in
-all the hairs the cystolith appears to be attached to the upper
-curved part of the inner wall of the hair.
-
-[Illustration: PLATE 85
-
-                          SOLITARY CRYSTALS
-
-  1. India senna (_Cassia angustifolia_, Vahl.).
-  2. Cascara sagrada bark (_Rhamnus purshiana_, D. C.).
-  3. Frangula bark (_Rhamnus frangula_, L.).
-  4. White pine bark (_Pinus strobus_, L.).
-  5. Tamarac bark (_Larix laricina_ [Du Roi], Koch).]
-
-[Illustration: PLATE 86
-
-                          SOLITARY CRYSTALS
-
-  1. Quassia (_Picræna excelsa_ [Swartz.], Lindl.).
-  2. Uva-ursi leaf (_Arctostaphylos uva-ursi_ [L.], Spring.).
-  3. Quebracho bark (_Aspidosperma quebracho-blanco_, Schlechtendal).
-  4. Wild-cherry bark (_Prunus serotina_, Ehrh.).]
-
-[Illustration: PLATE 87
-
-         ROSETTE CRYSTALS AND SOLITARY CRYSTALS OCCURRING IN
-
-  1. Cascara sagrada bark (_Rhamnus purshiana_, D.C.).
-  2. Frangula bark (_Rhamnus frangula_, L.).
-  3. Cundurango bark (_Marsdenia cundurango_, [Triana] Nichols).
-  4. Dogwood root bark (_Cornus florida_, L.).
-  5. Pleurisy root (_Asclepias tuberosa_, L.).]
-
-[Illustration: PLATE 88
-
-                             CYSTOLITHS
-
-  1. Ruellia root (_Ruellia ciliosa_, Pursh.).
-  2. Pellionia leaf.
-  3. Cannabis indica (_Cannabis sativa_, variety _Indica_, Lam.).]
-
-Cystoliths occur, then, in special cavities, in parenchyma
-cells (rubber-plant leaf, fig, pellionea, and mulberry), and in
-non-glandular hairs (cannabis indica).
-
-In powdered ruellia root the cystoliths occur in or are separated
-from the parenchyma cells.
-
-
-                        TESTS FOR CYSTOLITHS
-
-When dilute hydrochloric acid or acetic acid is added to cystoliths a
-brisk effervescence takes place with the evolution of carbon dioxide
-gas.
-
-
-
-
-                              Part III
-
-                HISTOLOGY OF ROOTS, RHIZOMES, STEMS,
-                   BARKS, WOODS, FLOWERS, FRUITS,
-                              AND SEEDS
-
-
-In Part II the different types of cells and cell contents found in
-plants have been studied. In Part III it will be shown how these
-different cells are associated and the nature of the cell contents
-in the different parts of the plant. These parts are the root, the
-rhizome, the stem of herbs, bark and wood of woody stems, the leaf,
-the flower, the fruit, and the seed.
-
-
-
-
-                              CHAPTER I
-
-                         ROOTS AND RHIZOMES
-
-
-Some fifty-five roots, rhizomes, and rhizomes and roots are official
-in the pharmacopœia and national formulary. About 5 of these are
-obtained from monocotyledonous plants, and 50 from dicotyledonous
-plants.
-
-In studying the structure of roots and rhizomes, then, it must first
-be determined whether the root in question is monocotyledonous or
-dicotyledonous. This fact is ascertained by determining the type of
-the fibro-vascular bundle. The bundle is of the open collateral type
-in all rhizomes and roots obtained from monocotyledonous plants, but
-it is closed, radial, or concentric in the monocotyledonous type.
-
-In both of these groups the cellular plan of structure is similar,
-the chief variation being the absence of one or more types of cells,
-the variation in the amount, in arrangement, in the anatomical
-structure, in the color, and in the cell contents of the individual
-cells. These facts will be impressed on the mind while studying the
-rhizomes and the roots.
-
-
-                       CROSS-SECTION PINK ROOT
-
-The cross-section of pink root (Plate 89) has the following structure:
-
-=Epidermis.= The epidermal cells are small, nearly as long as broad,
-and the outer wall is thicker and darker in color than the side and
-inner walls. The cells usually contain air.
-
-=Cortex.= The cortical parenchyma cells are very large and somewhat
-rounded in outline, and the walls are white. There are about twelve
-rows of these cells, and each cell contains numerous small, rounded
-starch grains.
-
-=Endodermis.= The endodermal cells are tangentially elongated, and
-the walls are very thin and white. There are two or three layers of
-endodermal cells; the cells’ outer layers are larger than the cells
-of the inner layers.
-
-[Illustration: PLATE 89
-
-          CROSS-SECTION OF ROOT OF SPIGELIA MARYLANDICA, L.
-
-  1. Epidermis. 2. Cortical parenchyma. 2´. Intercellular space. 3.
-  Endodermis. 4. Pericycle. 5. Cambium. 6. Xylem. 7. Pith.]
-
-=Pericycle.= The cells forming the pericycle are sieve cells and
-phloem parenchyma. The =sieve cells= are small, angled cells with
-extremely thin, white walls.
-
-The =phloem parenchyma= resemble the sieve cells, except that they
-are larger.
-
-=Cambium.= The cambium cells are rectangular in shape; the walls are
-thin and white.
-
-=Xylem.= The xylem is composed of tracheids, wood parenchyma, and
-wood fibres.
-
-=Tracheids.= The tracheids are the largest diameter cells of the
-centre of the root. The walls are thick and the cells are slightly
-angled in outline.
-
-=Wood Parenchyma.= The wood parenchyma cells surrounding the
-tracheids are five to seven, angled, and the walls are not so thick
-as the walls of the tracheids.
-
-=Medullary Rays.= The medullary ray cells resemble the structure of
-the wood parenchyma cells, but they are radially elongated.
-
-=Pith Parenchyma.= The cells forming the pith parenchyma are larger
-than the cells of wood parenchyma, but their structure is similar.
-
-
-                     CROSS-SECTION RUELLIA ROOT
-
-The cross-section of ruellia root (Plate 90) shows the following
-structure. It should be carefully noted how the structure differs
-from that of pink root:
-
-=Epidermis.= The epidermal cells are angled and variable in size;
-many of the epidermal cells are modified as root hairs.
-
-=Hypodermis.= The cells of the hypodermis are one layer in thickness
-and their structure is similar to the epidermal cells.
-
-=Cortex.= The cortex contains parenchyma and stone cells. The outer
-layers of the cortical parenchyma cells are round in outline, and
-they contain dark-brown cell contents, while the cortical parenchyma
-cells bordering on the endodermis are small and they are free of
-dark-brown contents.
-
-Many of the inner parenchyma cells contain amorphous deposits of
-calcium carbonate.
-
-[Illustration: PLATE 90
-
-              RUELLIA ROOT (_Ruellia ciliosa_, Pursh.).
-
-  1. Epidermis with root hair. 2. Parenchyma cells with dark
-  contents. 3. Sclerid. 4. Parenchyma without dark cell contents. 5.
-  Endodermis. 6. Bast fibers and phloem. 7. Cambium. 8. Xylem. 10.
-  Pith.]
-
-The =stone cells= are porous and striated, and the walls are thick
-and white.
-
-=Endodermis.= The endodermal cells are tangentially elongated, and
-the walls are thin and white.
-
-=Pericycle.= The cells forming the pericycle are the sieve cells,
-bast fibres, and phloem parenchyma.
-
-The =sieve cells= are small, angled cells with thin, white walls.
-
-The =phloem parenchyma= cells resemble the sieve cells, but they are
-larger.
-
-The =bast fibres= occur singly or in groups of two or three. They
-are rounded in outline, and the walls are white, non-porous, and
-non-striated.
-
-=Xylem.= The xylem is composed of vessels, wood parenchyma, and wood
-fibres.
-
-=Vessels.= The vessels are rounded in outline and few in number.
-
-=Wood Parenchyma.= The wood parenchyma cells are variable in size and
-shape, but all the cells are angled in outline.
-
-=Medullary Rays.= The medullary ray cells are not clearly
-distinguishable.
-
-=Pith Parenchyma.= The pith parenchyma cells of the centre of the
-root resemble the cortical parenchyma cells.
-
-That the structure of rhizomes is similar to the structure of roots
-is shown by the drawings of spigelia rhizome (Plate 91), and by
-ruellia rhizome (Plate 92).
-
-
-                   CROSS-SECTION SPIGELIA RHIZOME
-
-The cross-section of spigelia rhizome (Plate 91) is as follows:
-
-=Epidermis.= The epidermal cells are nearly angled and free of cell
-contents.
-
-=Cortex.= The cortical parenchyma cells are usually slightly
-tangentially elongated. The cells of the outer layers are larger than
-the cells of the inner layers.
-
-=Phloem.= The phloem contains sieve cells and phloem parenchyma. The
-sieve cells are small, angled cells with thin, white walls.
-
-The phloem parenchyma cells resemble the sieve cells, but they are
-larger.
-
-[Illustration: PLATE 91
-
-        CROSS-SECTION OF RHIZOME OF SPIGELIA MARYLANDICA, L.
-
-  1. Epidermis. 2. Cortical parenchyma. 3. Phloem. 4. Cambium. 5.
-  Xylem. 6. Internal phloem. 7. Pith with starch.]
-
-[Illustration: PLATE 92
-
-         CROSS-SECTION OF RHIZOME OF RUELLIA CILIOSA, Pursh.
-
-  1. Epidermis. 2. Cystolith. 3. Stone cell. 4. Cortical parenchyma.
-  5. Bast fibres. 6. Pericycle. 7. Xylem. 8. Pith.]
-
-=Cambium.= The cambium cells are rectangular, and they are usually
-not clearly seen because the walls are partially collapsed.
-
-=Xylem.= The xylem is composed of vessels, wood parenchyma, medullary
-rays, and pith parenchyma.
-
-=Vessels.= The vessels are slightly angled in outline and few in
-number.
-
-=Wood Parenchyma.= The wood parenchyma cells are small and angled.
-
-=Medullary Rays.= The medullary ray cells are tangentially elongated,
-but in structure resemble the wood parenchyma cells.
-
-=Pith Parenchyma.= The pith parenchyma cells are rounded in outline
-and contain small, simple, rounded starch grains.
-
-
-                    CROSS-SECTION RUELLIA RHIZOME
-
-The cross-section of ruellia rhizome (Plate 92) differs from the
-structure of spigelia rhizome. It is as follows:
-
-=Epidermis.= The epidermal cells vary in shape from nearly square to
-oblong, and they are filled with dark-brown cell contents.
-
-=Cortex.= The cortex contains parenchyma and stone cells.
-
-The outer layer of the cortical parenchyma cells are variable in size
-and many of the cells contain deposits of calcium carbonate and dark
-cell contents; the inner parenchyma cells are larger and they are
-free of the dark-brown cell contents, but many of the cells contain
-deposits of calcium carbonate.
-
-Stone cells with thick, white, porous, and striated walls occur in
-among the cortical parenchyma cells.
-
-=Phloem.= The phloem contains sieve cells, phloem, parenchyma, and
-bast fibres.
-
-The =sieve cells= are small and with thin, white, angled walls.
-
-The =phloem parenchyma= cells resemble the sieve cells, but they are
-larger.
-
-The =bast fibres= occur singly or in groups of two or three. The
-walls are white, non-porous, and non-striated.
-
-=Cambium.= The cambium layer is composed of rectangularly shaped
-cells, which are frequently obliterated.
-
-=Xylem.= The xylem contains vessels, wood parenchyma, and medullary
-rays.
-
-The =vessels= are large, rounded cells with thick walls.
-
-The wood parenchyma consists of thick-walled cells of irregular size
-and form.
-
-The =medullary rays= are tangentially elongated and rectangular in
-form.
-
-=Pith parenchyma.= The pith parenchyma cells are rounded in outline
-and as large as the cortical parenchyma cells.
-
-
-                         POWDERED PINK ROOT
-
-When the roots and rhizomes of spigelia are powdered (Plate 93) they
-show the following structure:
-
-The epidermal cells are small and brownish on surface view, varying
-in size from 13 by 18 micromillimeters to 31 by 40 micromillimeters.
-When associated with parenchyma they appear as black masses. The
-cortical parenchyma cells are rounded and vary in size from 23 by
-26 micromillimeters to 37.5 by 90 micromillimeters. Many of the
-cells from the root contain larger quantities of minute single
-rounded starch grains varying in size from 1 micromillimeter to 4
-micromillimeters. The larger round single starch grains are found in
-both the cortical and pith parenchyma of the rhizome. They vary in
-size from 5 micromillimeters to 18 micromillimeters. The conducting
-elements are pitted tracheids varying from 10 micromillimeters to 38
-micromillimeters in diameter. A few pitted and annular vessels are
-also found. The only fibres occurring are found in the xylem. They
-are not a prominent feature of the powder, as their walls break up
-into minute fragments. The pith parenchyma varies in size from 13 by
-19 micromillimeters to 75 by 82.5 micromillimeters. It is in these
-cells that the largest starch grains occur.
-
-Distinguishing diagnostic characters of the powder:
-
-  1. Parenchyma with starch.
-
-  2. Dark masses of epidermal tissue.
-
-  3. Spigelia should contain starch, and it should not contain
-  cystoliths, stone cells, or long, white-walled bast fibres.
-
-
-                        POWDERED RUELLIA ROOT
-
-When the roots of ruellia root and rhizome are powdered (Plate 94)
-they show the following structure:
-
-[Illustration: PLATE 93
-
-                  POWDERED SPIGELIA MARYLANDICA, L.
-
-  1. Epidermis and cortical parenchyma. 2. Tracheids and fibres. 3.
-  Parenchyma cells of the root containing the small starch grains,
-  longitudinal view. 4. Parenchyma of the rhizome containing the
-  large starch grams, transverse view. 5. Tracheids. 6. Surface view
-  of the epidermal cells. 7. Starch scattered through the field. 8
-  and 8´. Dark masses of epidermal and underlying tissue.]
-
-[Illustration: PLATE 94
-
-                  POWDERED RUELLIA CILIOSA, Pursh.
-
-  1. Short, broad cystoliths from the rhizome, 1´. Long cystoliths
-  from the root. 2 and 2´. Long, narrow, white-walled bast fibres. 3.
-  Tracheal tissue from the xylem of the stem. 4. Root parenchyma. 5.
-  Tracheal tissue from the xylem of the root. 6. Cortical parenchyma
-  cells from the rhizome with short, broad cystoliths. 7 and 7´.
-  Long, thick-walled sclerids from the root. 8. Short, broad sclerids
-  from the stem. 9. Pitted pith parenchyma from the stem with
-  intercellular space. 10. Parenchyma of the root with sclerid and
-  cystolith, longitudinal view.]
-
-The epidermal cells vary from 7.8 by 15.6 micromillimeters to 15.1
-by 16.6 micromillimeters. The cell contents are dark and the walls
-are light. A few rows of the outer cortical parenchyma cells of both
-the rhizome and the root have dark cell contents and white walls. The
-dark contents disappear toward the phloem. The cortical cells vary
-from 13.6 by 14.3 micromillimeters to 89.5 by 90.9 micromillimeters.
-In the cortical parenchyma cells of the rhizome are found the short,
-broad cystoliths measuring up to 52 by 62 micromillimeters. In the
-corresponding cells of the root are found the long, narrow cystoliths
-which measure up to 68.4 by 187.2 micromillimeters. Scattered
-throughout the powder are seen three distinct types of sclerids
-(stone cells) which are associated with the cortical parenchyma of
-both the stem and the root. Most of them are found, however, in
-the roots. First, the short, broad stone cells from the stem basis
-have square ends; the walls vary from 13 to 19.5 micromillimeters
-in thickness with branching pores which extend toward the adjacent
-cell. These sclerids vary in size from 52 by 54.6 micromillimeters
-to 45 by 130 micromillimeters. Secondly, the long stone cells from
-the root vary from 32 by 96 micromillimeters to 45.5 by 542.5
-micromillimeters with walls 16 micromillimeters thick. The width of
-the cell and the thickness of the wall vary but little throughout
-their entire length. The third type of stone cell also from the root
-has unequally thickened walls and the ends are square or blunt. A few
-long, narrow, colorless, thin-walled bast fibres also occur. They
-are 13 micromillimeters wide, with walls 3.9 micromillimeters thick.
-Annular spiral and pitted vessels are also found scattered throughout
-the powder.
-
-The diagnostic characters of the powder are:
-
-  1. The short, broad, and long, narrow cystoliths.
-
-  2. The short, broad, and long, narrow sclerids.
-
-  3. The long, narrow, thin, white-walled bast fibres.
-
-In poke root, ipecac, sarsaparilla, and veratrum are raphides. In
-belladonna and horse-nettle roots are micro-crystals. In calumba,
-stillingea, krameria, licorice, scamony root are prisms. In
-saponaria, jalap, althea, spikenard, rumex, rhubarb are rosette
-crystals. In pleurisy roots both prisms and rosettes occur.
-
-In gentian, senega, symphytuns, lovage, parsley, inula, echinacea,
-angelica, burdock, and chicory no crystals of any kind occur. Root
-hairs occur in cross-sections of sarsaparilla root and false unicorn,
-but with these exceptions: root hairs do not occur on roots, because
-the younger part of the root with root hairs is not removed from
-the soil when the drug is collected. In sarsaparilla root there
-are several layers of hypodermal cells; in most roots there are no
-hypodermal cells. In the non-woody roots or the roots of herbs the
-parenchyma cells form the greater part of the tissues of the root.
-In ruellia root are stone cells; in spigelia root and many other
-roots there are no stone cells. In ruellia root are bast fibres; in
-spigelia, gentian, ipecac, chicory, dandelion, symphytum, and lovage
-no bast fibres occur. In all the woody roots there is a periderm
-consisting of typical cork cells, as in black haw; or stone cells, as
-in asclepias; or of a mixture of lifeless parenchyma, medullary rays,
-etc., as in Oregon grape root.
-
-Woody roots have a phellogen layer which is absent in the non-woody
-roots.
-
-The numbers of layers of cortical parenchyma differ in the same
-root according to its age, but for a given root there is a normal
-variation.
-
-The number of layers of cortical parenchyma in proportion to other
-cells is less in woody roots.
-
-In woody roots there is no endodermis. The cambium in these
-cases shows clearly between the phloem and the xylem part of the
-fibro-vascular bundle.
-
-In woody roots the wood fibres are well developed and form a large
-part of the root, and the medullary rays have pitted side and end
-walls.
-
-The description given above of ruellia root is not typical of all
-roots, but the structure represents the greater number of the
-elements that it is possible to find in a root. In many roots, for
-instance, there are no stone cells, in others no epidermis and no
-endodermis. In asclepias, aconite, and calumba stone cells occur.
-In symphytum, chicory, dandelion, burdock, elecampane, pyre thrum,
-gentian, and senega no stone cells occur. In aconite, althea,
-asclepias, belladonna, bryonia, columba, ipecac, jalap, krameria,
-sarsaparilla, scamony, stillingea, and rumex are characteristic
-starch grains. Symphytum, chicory, dandelion, burdock, elecampane,
-and pyrethrum contain inulin, but no starch. In saponaria, gentian,
-and senega neither starch nor inulin occurs.
-
-When studying roots the nature of the epidermis or the periderm must
-be considered, as also the number of layers of cortical parenchyma;
-the occurrence, distribution, and amount of stone cells when present;
-the presence or absence of the endodermis; the occurrence and
-structure of bast fibres when present; the nature of the cambium
-cells; the width and structure of the medullary rays, the size of the
-wood fibres and wood parenchyma, and the nature of the cell contents
-and the arrangement of the fibro-vascular bundle.
-
-
-
-
-                             CHAPTER II
-
-                                STEMS
-
-
-When studying stems it should first be determined whether they were
-derived from monocotyledonous or dicotyledonous plants. This fact is
-ascertained by determining the type of the fibro-vascular bundle. See
-Chapter XI. The next fact to determine is whether the stem is from an
-herb or from a woody plant. This fact is readily determined because
-herbaceous stems have a true epidermis, masses of collenchyma at
-the angles of the stem. The cortical cells contain chlorophyll, and
-the pith is very large. Woody stems have a corky layer, a phellogen
-layer, and the pith is very small except in the very young woody
-stems.
-
-Having determined these facts, a study should be made of the
-arrangement, form, structure, color, and the cell contents of the
-different cells in order to determine the species of plant from which
-the stem was obtained.
-
-
-                          HERBACEOUS STEMS
-
-The great variation in the structure of herbaceous stems is shown
-in the cross-sections of spigelia (Plate 95); in ruellia (Plate
-96); in the charts of powdered genuine horehound, powdered spurious
-horehound, and in the chart of powdered insect flower stems.
-
-
-                     CROSS-SECTION SPIGELIA STEM
-
-Spigelia stem (Plate 95) has the following characteristic structure:
-
-=Epidermis.= The epidermal cells are papillate.
-
-=Cortex.= The cortical parenchyma cells consist of tangentially
-elongated cells which are oval in outline.
-
-=Phloem.= The phloem consists of sieve cells, phloem parenchyma, and
-of bast fibres.
-
-[Illustration: PLATE 95
-
-          CROSS-SECTION OF STEM OF SPIGELIA MARYLANDICA, L.
-
-  1. Papillate epidermis.     4. Phloem.     7. Inner phloem.
-  2. Cortical parenchyma.     5. Cambium.    8. Pith.
-  3. Bast stereome.           6. Xylem.]
-
-The =sieve cells= are small, and with thin, white, angled walls.
-
-The =phloem parenchyma= resembles the sieve cells, but they are
-larger.
-
-The bast fibres are rounded in outline and the walls are thick,
-white, non-porous, and non-striated.
-
-=Cambium.= The cambium cells are rectangular in shape or the walls
-are collapsed and the cells indistinct.
-
-=Xylem.= The xylem contains vessels, wood parenchyma, medullary rays.
-The vessels are small and angled, the walls are thick and white.
-
-=Wood parenchyma.= The cells are variable in size and shape, and
-the walls are thick. The medullary ray cells are small, narrow, and
-tangentially elongated.
-
-=Internal Phloem.= External to the pith parenchyma are isolated
-groups of internal phloem consisting of sieve cells.
-
-=Pith Parenchyma.= The pith parenchyma cells are oval in form and
-irregularly placed. The cells contain small, simple starch grains.
-
-
-                            RUELLIA STEM
-
-The cross-section of ruellia stem (Plate 96) is as follows:
-
-=Epidermis.= The epidermal cells are variable in shape and very
-large. There are no cell contents.
-
-=Cortex.= The cortex consists of collenchyma and parenchyma cells and
-stone cells.
-
-The =collenchyma cells= have very small, angled cavities and very
-thick walls. These cells make up the greater part of the cortex.
-
-The =cortical parenchyma= cells are variable in size and shape. The
-stone cells occur singly or in groups. The walls are thick, white,
-porous, and striated, and the central cavity is frequently quite
-large.
-
-=Phloem.= The phloem contains sieve cells, phloem parenchyma, and
-bast fibres.
-
-The =sieve cells= have thin, white, angled walls.
-
-The =phloem parenchyma= cells are frequently tangentially elongated,
-otherwise they resemble the sieve cells.
-
-The =bast fibres= occur alone or in groups. The walls are thick,
-white and porous.
-
-[Illustration: PLATE 96
-
-          CROSS-SECTION OF STEM OF RUELLIA CILIOSA, Pursh.
-
-  1. Epidermis. 2. Collenchyma. 3. Parenchyma. 4. Sclerids. 5. Bast
-  fibres. 6. Phloem. 7. Cambium cells. 8. Xylem. 10. Pith parenchyma.]
-
-=Cambium.= The cambium cells are rectangular in shape and the walls
-are thin.
-
-=Xylem.= The xylem contains vessels, wood parenchyma, and medullary
-rays.
-
-The =vessels= are large; the walls are thick, white, and angled.
-
-The =wood parenchyma= cells are variable in size and shape and the
-walls are angled.
-
-The =medullary ray cells= are radially elongated and rectangular in
-shape.
-
-=Pith Parenchyma.= The pith parenchyma cells are large and rounded in
-shape.
-
-
-                         POWDERED HOREHOUND
-
-The structure of powdered horehound is shown in Chart 97. The
-epidermal cells of the leaf (1) are wavy in outline, the guard cells
-are elliptical, the stoma lens-shaped, the epidermis often showing
-hairy outgrowth as in the illustration. The epidermal cells of the
-petals (2) have irregularly thickened beaded walls. The non-glandular
-hairs from the calyx (3); the long, thin-walled, multicellular
-non-glandular twisted hairs (4) from the leaves and stems; long,
-thin-walled, unicellular hairs (5) from the tube of the corolla; the
-glandular hairs (6) with a one-celled stalk and with two secreting
-cells divided by vertical walls; the eight-celled glandular hair
-(7) as seen in surface and side view; the spiral and reticulated
-conducting cells (8); the thick, white-walled fibres from the stem
-(9); the pollen grains (10) with nearly smooth walls.
-
-The diagnostic elements of the U. S. P. horehound are the long,
-twisted, multicellular hairs (4), the glandular hairs (7), and the
-pollen grains (10).
-
-
-                     POWDERED SPURIOUS HOREHOUND
-
-Marrubium peregrinum, which is a related species of horehound
-and which is a common adulterant of horehound, has the following
-structure (Plate 98):
-
-[Illustration: PLATE 97
-
-            POWDERED HOREHOUND (_Marrubium vulgare_, L).
-
-  1. Epidermis of leaf showing the wavy epidermal cells, stoma,
-  and a clustered hair. 2. Surface view of the petal epidermis. 3.
-  Non-glandular hair from the calyx or corolla. 4. Long, thin-walled,
-  twisted, non-glandular hairs from the leaves and stem. 5.
-  Unicellular non-glandular hair from the tube of the corolla. 6.
-  Glandular hairs with a one-celled stalk and with two secreting
-  cells divided by vertical walls. 7. Surface and side view of the
-  eight-celled glandular hairs. 8. Conducting cells. 9. Fibres from
-  the stem. 10. Pollen grains.]
-
-[Illustration: PLATE 98
-
-           SPURIOUS HOREHOUND (_Marrubium peregrinum_, L.)
-
-  1. Surface view of the leaf epidermis. 2. View of the petal
-  epidermis. 3. Non-glandular multicellular branched hair from
-  the stem, leaves, or flowers with a few of the lower branches
-  broken. 4. Broken pieces and branches from the compound hairs
-  scattered throughout the field. 5. Unicellular glandular hair
-  with a two-celled stalk. 6. Under-surface view of an eight-celled
-  glandular hair. 7. Side view of eight-celled glandular hair. 8.
-  Long, pointed, unicellular, non-glandular hair from the corolla,
-  the wall irregularly thickened near the apex. 9. Fibres. 10. Pollen
-  grains, 11. Conducting cells of leaf.]
-
-[Illustration: PLATE 99
-
-   POWDERED INSECT FLOWER STEMS (_Chrysanthemum cinerariifolium_,
-                           [Trev.], Vis.)
-
-  1. Surface view of epidermis.
-  2. Cross-section of epidermis.
-  3. Hairs.
-  4. Fibres.
-  5. Cross-section of fibres.
-  6. Longitudinal view of pith parenchyma.
-  7. Cross-section of pith parenchyma.
-  8. Conducting cells.]
-
-The wavy leaf epidermis (1) with stoma; the beaded wall petal
-epidermis (2); the non-glandular, multicellular branched hairs (3)
-from the stem leaves or flowers; the broken pieces and branches of
-the compound hairs (4) scattered throughout the field; the glandular
-hairs (5) with a two-celled stalk; the eight-celled glandular hair
-(7) seen in surface view and a side view (8) of a similar hair; the
-long, pointed, unicellular non-glandular hair from the tube of the
-corolla, the wall irregularly thickened near the apex; the fibres
-(9) from the stem; the pollen grains (10) with prominent centrifugal
-projections; the conducting cells.
-
-The diagnostic elements of marrubium peregrinum are the multicellular
-branched hairs (3) which occur on all parts of the plant, usually
-much broken in the powder, with walls many times thicker than the
-walls of the hairs found in U. S. P. horehound; the pollen grains
-(10) with centrifugal projections and the stalked glandular hairs (5).
-
-
-                         INSECT FLOWER STEMS
-
-Insect flower stems are the chief adulterant of insect flowers.
-Until the passage of the insecticide law, it was a common practice
-to sell (for insect powder) a mixture of powdered stems and flowers.
-Since the passage of the law, the presence of the stems in a powder
-is supposed to be declared on the label. In spite of the penalties
-attached, their presence in a powder is frequently not declared,
-as evidenced by a microscopical examination of the insect powders
-obtained in the open market.
-
-The structure of powdered insect flower stems (Chart 99) is as
-follows:
-
-The epidermal cells of the stems are prominently marked with stoma
-and angled, striated wall cells (Fig. 1). On cross-section (Fig.
-2) the stem is seen to be made up of epidermal cells with thick
-outer and thin side walls (Fig. 2). The T-shaped hairs (Fig. 3) are
-longer than those found on any other part of the plant. The fibres
-(Fig. 4) are the most characteristic part of the powder. They are
-elongated, and the walls are white and slightly porous and of nearly
-uniform thickness. They occur free in the field or in groups of two
-or more. The cross-section view of these fibres is shown in Fig. 5.
-The pith parenchyma (Fig. 6) is abundant and is composed of thick,
-porous-walled cells. On cross-section the cells are rounded and are
-separated by intercellular spaces. The conducting cells (Fig. 8) vary
-from spiral to reticulate.
-
-
-
-
-                             CHAPTER III
-
-                             WOODY STEMS
-
-                             BUCHU STEM
-
-
-The cross-section of a buchu stem (Plate C), 1.6 millimeters
-in diameter, shows a few of the epidermal cells modified into
-thick-walled, roughish, unicellular trichomes (1). The remaining
-epidermal cells have a thick, wavy outer wall (2). Beneath the
-epidermis are several rows of cortical parenchyma cells (3) which
-extend to the bast bundles and in which are found the secretory
-cavities with the thin-walled secretory cells (4). The bast fibres
-(5) occur in continuous bands, varying greatly in size; the walls
-are whitish and of variable thickness. Inside the bast fibres, the
-small irregular sieve cells (6) occur in groups, surrounded by the
-phloem parenchyma (8). The radially elongated cells of the medullary
-rays (7) extend outward from the xylem, increasing in number in
-the outer portions of the wood, and extending nearly to the bast
-fibres. No distinct cambium layer is visible. The conducting cells
-(9) occur throughout the xylem surrounded by the wood fibres and
-wood parenchyma (10). The latter is not very abundant in buchu. The
-medullary rays border on the conducting cells and extend outward to
-the phloem. The pith parenchyma cells are nearly circular in outline
-and often show a perforated end wall when a cell happens to be cut
-just above or below that point.
-
-
-                          MATURE BUCHU STEM
-
-In Plate 101-A is shown the cork formation or secondary growth as
-seen in the older, larger buchu stems. The wavy epidermis (1),
-which is the primary epidermis and which has disappeared on many
-portions of the stem, has thin side walls and dark cell contents
-(2). Next to the epidermal cells occur several rows of peculiarly
-arched cork cells with thick, white outer walls (3) and reddish-brown
-cell contents (4). The cork cambium (5) is typical in form, and it
-has formed one or two layers of phelloderm cells (6) which have
-the same form as the cambium cells but with thicker walls. Next to
-the phelloderm occur the cortical parenchyma cells. The remaining
-structure of the mature stem is identical with that of Fig. 2.
-
-[Illustration: PLATE 100
-
-      CROSS-SECTION OF BUCHU STEMS (_Barosma betulina_ [Berg.],
-                         Barth, and Wendl.)
-
-  1. Hairs. 2. Wavy epidermis. 3. Cortical parenchyma. 4. Secretion
-  cells and cavity. 5. Group of bast fibres. 6. Sieve cells. 7.
-  Medullary rays. 8. Phloem parenchyma. 9. Vessels. 10. Wood fibres,
-  and wood parenchyma. 11. Pith parenchyma.]
-
-[Illustration: PLATE 101
-
-  _A._ Cross-section of buchu stem (_Barosma betulina_ [Berg.],
-  Barth. and Wendl.). 1, Outer wall of epidermis; 2, Cell cavity of
-  epidermal cell; 3, Wall of cork cell; 4, Cavity of cork cell; 5,
-  Phellogen layer; 6, Divided phellogen cell changing into a cortical
-  parenchyma cell; 7, Cortical parenchyma cell.
-
-  _B._ Cross-section of leptandra rhizome (_Leptandra virginica_
-  [L.], Nutt.). 1, Parenchyma cells undergoing change in the
-  composition of their walls; 2, A break in the epidermal tissue; 3,
-  Parenchyma cells undergoing division.]
-
-
-                         POWDERED BUCHU STEM
-
-Powdered buchu stem (Plate 102) has many striking features which
-make it easy of identification when mixed with buchu leaves. A
-few unicellular, rough, thick, white-walled trichomes (1) occur
-distributed throughout the field. They are straight or slightly
-curved and vary in length from 40 to 100 microns; in thickness at the
-bast they measure from 10 to 22 microns. The central cavity varies
-greatly, and in some trichomes seems to have disappeared entirely.
-The epidermal cells (2) are very characteristic, occurring singly
-or in groups of two or more. The cells from the older stems often
-appear reddish brown by transmitted light, while the epidermal cells
-from the younger stems appear whitish opaque (porcelain-like).
-They are usually six-sided and angular in outline. The cortical
-parenchyma cells (3) on transverse view have a rounded cell cavity
-and intercellular spaces between the walls. The double walls vary
-in thickness, the greatest thickness being about 9 microns. The
-parenchyma cells (3) on longitudinal view show square ends and often
-contain sphæro-crystalline masses of hesperidin. The thin-walled
-sieve cells and the surrounding cells are scarcely ever seen in the
-powder. The white-walled pointed stereomes (4) are a characteristic
-feature of the powder; they vary greatly in length, in diameter and
-in the thickness of their walls. In a number eighty powder the fibres
-are mostly broken. The greatest length of the unbroken fibres is
-1.25 microns. The thickest wall measured 5 microns and the greatest
-observed width was 25 microns. The spiral reticulate and scalariform
-thickened conducting cells occur scattered throughout the powder. The
-reticulate and scalariform cells usually occur with wood fibres. It
-is an interesting fact that the spiral thickening in conducting cells
-is usually separate from the side wall and nearly always appears as
-indicated at 5. An occasional rosette crystal of calcium oxalate (6)
-is seen in the field. The wood parenchyma (7), which makes up a very
-small percentage of the xylem, is not readily found in the powder.
-The pith parenchyma cells (8) have thick, porous side walls and
-perforated side walls. The wood fibres (9) usually occur in masses
-surrounding the conducting cells; when occurring singly, the oblique
-pores readily distinguish them from the bast fibres.
-
-[Illustration: PLATE 102
-
-          POWDERED BUCHU STEMS (_Barosma betulina_ [Berg.],
-                         Barth. and Wendl.).
-
-  1. Hairs. 2. Epidermal cells, the larger pieces reddish-brown; the
-  smaller aggregations white. 3. Transverse cortical parenchyma.
-  3’ Longitudinal cortical parenchyma with sphæro crystalline
-  masses of hesperidin. 4. Bast fibres. 5. Spiral, sclariform, and
-  reticulate vessels. 6. Rosette crystals of calcium oxalate. 7. Wood
-  parenchyma. 8. Pith parenchyma with porous side and end walls. 9.
-  Wood fibres.]
-
-The diagnostic elements of powdered buchu stems are:
-
-First, trichomes; secondly, reddish-brown and white-angled epidermal
-cells; thirdly, the long, white bast fibres.
-
-
-
-
-                             CHAPTER IV
-
-                                BARKS
-
-
-Barks are all obtained from dicotyledonous plants. In studying
-barks there should be ascertained the thickness, arrangement, form,
-structure, color, and cell contents of the cells occurring in the
-_outer_, _middle_, and _inner_ barks.
-
-The outer bark includes the cork cells and the phellogen layer. The
-middle bark includes all the cells occurring between the phellogen
-layer and the beginning of the medullary rays. The inner bark
-includes the medullary ray cells and all cells associated with them.
-The plan of structure of all barks is similar, but in each species of
-plant the structure of the bark is uniform and characteristic for the
-species.
-
-A great number of drugs consist of the bark of woody plants; for this
-reason the bark is considered in a separate chapter from the stem.
-
-
-                           WHITE PINE BARK
-
-The cross-section of white pine bark (Plate 103) has the following
-structure:
-
-=Outer Bark.= The periderm consists of several layers of
-reddish-brown cork cells (1) which are narrow, elongated, and with
-thin walls.
-
-=Middle Bark.= The cells forming the middle bark are parenchyma and
-secretion cells.
-
-The =parenchyma cells= vary greatly in size, form, and thickness of
-the walls. The cells beneath the cork cells and around the secretion
-cells are tangentially elongated and oval in shape, while the other
-parenchyma cells are more irregular in shape.
-
-The secretion cells are arranged around the schizogenous secretion
-cavities. The cells are tangentially elongated, and the walls, which
-are slightly papillate, are white.
-
-=Inner Bark.= The cells forming the inner bark are medullary rays,
-parenchyma, sieve cells, and storage cavities.
-
-[Illustration: PLATE 103
-
-   CROSS-SECTION OF UNROSSED WHITE PINE BARK (_Pinus strobus_, L.)
-
-  1. Cork cells of the epidermis. 2. Parenchyma cells filled with
-  chlorophyl. 3. Intercellular space. 4. Secretion cavity with resin.
-  5. Secretion cells. 6, One or more circles of parenchyma filled
-  with chlorophyl. 7. Parenchyma. 8. Medullary rays. 9. Sieve cells.
-  10. Storage cavities.]
-
-The =medullary rays= form wavy lines. The medullary ray cells are
-radially elongated, rectangular in shape, and they contain granular
-cell contents. The sieve cells are either square or rectangular in
-shape. The walls are thin and white. The storage cavities are either
-filled with starch or with prisms and tannin.
-
-
-                      POWDERED WHITE PINE BARK
-
-White pine bark (Plate 104) when powdered shows the following
-characteristic elements:
-
-The microscopic structure of a powdered white pine is as follows: The
-epidermis (1) consists of reddish-brown masses, irregular in outline.
-The outer parenchyma cells are of a bright-green color, owing to the
-presence of chlorophyll. (The above elements are not usually found in
-the rossed bark.) The parenchyma (3) with starch usually occurs in
-longitudinal sections accompanied with sieve cells. Often the tissue
-separates transversely, showing the medullary rays (4) with their
-granular cell contents (9) and the inner parenchyma cells filled with
-starch and the surrounding sieve cells.
-
-The crystals are nearly perfect cubes and occur singly (5) or in
-groups (6). On the longitudinal section of the bark the crystals
-occur in parenchyma cells surrounded by a reddish cell content and
-form parallel rows which are very characteristic. The resin occurs
-either as white, angled fragments (7) in a water mount, or as
-globular mass (8) or as reddish-brown pieces (10). The starch is very
-abundant and is distributed through the field. The diagnostic grain
-is lens-shaped, with a cleft hilum, which is nearly straight, or
-slightly curved, and runs parallel to the long diameter of the grain.
-The addition of ferric chlorid T. S. will show the presence of tannin
-by forming a dark coloration. The identification of the starch is
-facilitated by the addition of a weak Lugol’s solution, which imparts
-a blue coloration to the starch grain.
-
-The form, amount, and distribution of the cells composing the bark
-differ greatly in different plants.
-
-In cramp bark the cork and phellogen cells are very large, while in
-cascara sagrada the phellogen and the cork cells are very small.
-
-[Illustration: PLATE 104
-
-           POWDERED WHITE PINE BARK (_Pinus strobus_, L.)
-
-  1. Epidermis. 2. Parenchyma cells. 3. Parenchyma with starch. 4.
-  Medullary rays. 5. Solitary crystals. 6. Solitary crystals and
-  tannin. 7, 8 and 10. Resin masses. 9. Starch.]
-
-In canella alba bark the periderm is composed of stone cell cork
-or stone cells arranged in superimposed rows, which form the outer
-layers of the bark.
-
-In white oak and most barks from woody trees the periderm consists of
-lifeless parenchyma, medullary rays, sieve cells, bast fibres, and in
-some cases stone cells and of phellogen cells.
-
-In young wild cherry, cascara sagrada, and frangula are several
-layers of tangentially elongated collenchyma cells with chlorophyll.
-In the older barks of the above and in many other barks no
-collenchyma cells occur.
-
-In cramp bark and in tulip tree bark the outer layers of the cortical
-parenchyma cells are beaded. In most barks there is no beaded walled
-parenchyma. The outer layers of most cortical parenchyma cells are
-tangentially elongated while the inner parenchyma cells are mostly
-circular in outline.
-
-In white oak, cascara sagrada and prickly ash are groups of stone
-cells; in the cinnamon barks are bands of stone cells; in cinchona
-bark are isolated stone cells. In cramp bark, mezerum, elm, and white
-pine bark no stone cells occur.
-
-In frangula, cascara sagrada, cocillina, cinnamon, cinchona,
-sassafras, and wild cherry barks the bast fibres occur in groups.
-In frangula, cascara sagrada, and cocillina the bast fibres are
-surrounded by crystal cells with crystals.
-
-In sassafras bark mucilage cells occur. In canella alba, white pine,
-and sassafras barks secretion cells occur; but in most barks no
-secretion cells occur.
-
-In sassafras bark the medullary ray cells are nearly as broad as
-long; in cramp bark they are elongated and oval in shape. In cascara
-sagrada, as in most barks, the cells are longer than broad and
-rectangular in shape.
-
-In cascara sagrada the sieve cells are very large; in granatum bark
-the sieve cells are very small.
-
-In cassia cinnamon and in canella alba bark the walls of the sieve
-cells have collapsed, with the result that the sieve cells have
-become partly obliterated.
-
-In witch-hazel, mountain maple, willow, and black walnut are found
-prisms; in cramp bark, black haw, wahoo, pomegranate, and cotton root
-bark are found rosette crystals; in the cinnamon barks are found
-raphides; in cinchona bark, micro-crystals.
-
-In cocillina, frangula, cascara sagrada, white oak, poplar and
-Jamaica dogwood barks are found crystal-bearing fibres (Plates 19 and
-20).
-
-When studying barks we must consider the kind, structure, and amount
-of the periderm; the nature of the phellogen; the nature and amount
-of the cortical parenchyma; the occurrence, distribution, and amount
-of stone cells, when present; the occurrence and structure of the
-bast fibres; the presence or absence of secretion cells; the width,
-distribution, and structure of the medullary rays.
-
-
-
-
-                              CHAPTER V
-
-                                WOODS
-
-
-Quite a number of drugs consist of the =wood= of woody plants; such
-drugs are quassia, red saunders, white sandalwood, and guaiac.
-
-When studying woods it is necessary to observe the cross, tangential,
-and radial sections. Such sections of quassia are shown in Plates
-105, 106, and 107. When studying these sections it should be
-remembered that while the types of cells forming quassia wood are
-similar to the cells forming other woods, still their structure,
-arrangement, and amount will vary in a recognizable way in the
-different woods.
-
-
-                        CROSS-SECTION QUASSIA
-
-Plate 105 is a cross-section of quassia. It has the following
-structure:
-
-=Vessels.= The vessels occur singly or in groups of two to eight
-cells. The cells are variable in size and shape. The walls are
-yellowish white and porous.
-
-=Medullary Rays.= The medullary rays vary from one to five cells in
-width.
-
-The =medullary ray cells= are radially elongated and the walls are
-strongly porous.
-
-=Wood Parenchyma.= The wood parenchyma cells have thin,
-yellowish-white, angled walls.
-
-=Wood Fibres.= The wood fibres have thick, yellowish-white, angled
-walls. These cells are smaller in diameter than the wood parenchyma
-cells.
-
-
-                       RADIAL SECTION QUASSIA
-
-The radial section of quassia (Plate 107) is as follows:
-
-=Vessels.= The vessels appear as in the tangential section.
-
-=Medullary rays.= The medullary rays vary from ten to twenty cells in
-height according to the part of the medullary ray bundle cut across.
-
-[Illustration: PLATE 105
-
-   CROSS-SECTION OF QUASSIA WOOD (_Picræna excelsa_ [Sw.], Lindl.)
-
-  1. Vessels.
-  2. Medullary rays.
-  3. Wood parenchyma.
-  4. Wood fibres.]
-
-[Illustration: PLATE 106
-
-TANGENTIAL SECTION OF QUASSIA WOOD (_Picræna excelsa_ [Sw.], Lindl.)
-
-  1. Vessel. 2. Wood parenchyma. 3. Wood fibre. 4. End wall of
-  medullary ray cell. 5. Medullary ray bundle.]
-
-[Illustration: PLATE 107
-
-  RADIAL SECTION OF QUASSIA WOOD (_Picræna excelsa_ [Sw.], Lindl.)
-
-  1. Showing the height and length of the medullary rays and cells.
-  2. Cells with starch.
-  3. Wood parenchyma and wood fibres.]
-
-The =medullary ray cells= exhibit their height and length. The walls
-of the cells are yellowish white and strongly porous.
-
-=Wood Parenchyma.= The wood parenchyma cells have yellowish, thin
-walls and blunt end walls.
-
-=Wood Fibres.= The wood fibres have thick, yellowish-white walls, and
-the end of the cells are strongly tapering.
-
-
-                     TANGENTIAL SECTION QUASSIA
-
-The tangential section of quassia (Plate 106) shows the following
-structure:
-
-=Vessels.= The vessels are very long and broad and the yellow walls
-are marked with clearly defined pits.
-
-=Medullary Rays.= The tangential section shows the cross-section of
-the medullary ray bundle and the cross-section of the medullary ray
-cell.
-
-The =medullary ray bundle= varies in width from one to five cells.
-The ends of the bundles are always one cell in width, while the
-central part of the bundle is frequently five cells in width.
-
-The =medullary ray cell= varies in size, structure, and shape
-according to the part of the cell cut across. The cells cut across
-the centre show hollow spaces, but the cells cut just above or below
-the end wall show a strongly pitted surface. The cells forming the
-end of the bundle are larger than the cells forming the centre of the
-bundle.
-
-=Wood Parenchyma.= The wood parenchyma cells are greatly elongated
-and the walls are thin and yellowish white. The ends of the cells are
-blunt.
-
-=Wood Fibres.= The wood fibres are elongated, the walls are thick and
-the cells are strongly tapering.
-
-In quassia, white sandalwood, red sandalwood, and guaiac wood are
-characteristic crystals.
-
-In quassia the vessels are finely pitted, yellowish, and distinct; in
-white sandalwood the vessels are coarsely and sparingly pitted and
-white translucent; in red saunders the vessels are coarsely pitted,
-bright red and distinct.
-
-When studying woods we must consider the width of the medullary rays,
-the structure and cell contents of the medullary ray cells; the
-structure, color, and cell contents of the wood parenchyma; also the
-wood fibres.
-
-
-
-
-                             CHAPTER VI
-
-                               LEAVES
-
-
-Leaves collectively constitute the greatest manufacturing plant in
-the world. Most of the food, clothing, and medicine used by man
-is formed as a result of the work of the leaf. The cell contents,
-structure, and arrangement of the different cells of the leaf differ
-in a marked degree from the cell contents, structure, and arrangement
-of the cells in the other organs of the plant. This accounts for the
-presence of the large amount of chlorophyll in the leaf, the presence
-of stomata, and the peculiar arrangement of the cells.
-
-It should be ascertained if the stomata are above, even with, or
-below the epidermis; the nature of the epidermal cells, and, when
-present, the nature of the hypodermal cells; the number of layers of
-palisade parenchyma and whether it is present on both surfaces of the
-leaf, and the nature of the outgrowths from the epidermal cells.
-
-
-                             KLIP BUCHU
-
-The cross-section of klip buchu (Plate 108) has the following
-structure:
-
-=Epidermis.= The epidermal cells of klip buchu are modified to form
-papillæ, the walls are yellowish white, and the papillate portion of
-the cell is nearly solid.
-
-=Hypodermis.= The hypodermal cells are never intact because the
-mucilage contained in the cells swells when placed in water and
-breaks the thin side walls.
-
-=Upper Palisade Parenchyma.= The palisade parenchyma is two layers in
-thickness. The cells of the outer layer are greatly elongated and are
-packed with chlorophyll. The inner layer of palisade cells is more
-irregular, and the cells are much shorter than the cells of the outer
-palisade layer.
-
-[Illustration: PLATE 108
-
-           CROSS-SECTION OF KLIP BUCHU JUST OVER THE VEIN
-
-  _A._ Papillate upper epidermis.
-  _B._ Hypodermal cells with broken side walls, due to expansion of
-       mucilage contents.
-  _C._ Palisade cells, showing two cells filled with chlorophyll.
-  _D._ Palisade like mesophyll.
-  _E._ Endodermis.
-  _F._ Vascular strand of vein.
-  _G._ Conducting cells with spirally thickened walls.
-  _H._ Characteristic leaf mesophyll.
-  _I._ Short, thick palisade cells on the under side of leaf, just
-       under the vein.
-  _J._ Under hypodermal cells.
-  _K._ Papillate under epidermis.]
-
-=Spongy Parenchyma.= The spongy parenchyma cells are branched;
-therefore, large intercellular spaces occur between the cells.
-
-=Under Palisade Parenchyma.= The palisade cells of the under
-epidermis are short and broad, and they contain fewer chlorophyll
-grains than the upper palisade cells of the upper epidermis. These
-cells occur only under the veins.
-
-=Under Hypodermis.= The under hypodermal cells are shorter and
-broader than the upper hypodermal cells.
-
-=Under Epidermis.= The under epidermal cells are modified to form
-papillæ which are similar to the papillæ of the upper epidermis.
-
-=Fibro-Vascular Bundle.= The cells composing the vascular bundle are
-sieve cells, vessels, and fibres.
-
-The =sieve cells= are small and the walls are white and angled.
-
-The =vessels= have thick, white, angled walls.
-
-The =bast fibres= are rounded in outline and the walls are thick and
-white.
-
-=Endodermis.= The endodermal cells encircle the fibro-vascular
-bundles. The cells are large, thin-walled, and oval in shape.
-
-=Secretion Cells.= Near the edges of the leaf are schizogenous
-secretion cavities surrounded by thin-walled secretion cells.
-
-
-                         POWDERED KLIP BUCHU
-
-When the leaf is powdered (Plate 109), the cells are quite as
-characteristic in appearance. The upper epidermal cells (1) have
-thick-beaded, yellowish-white walls and papillate outer walls. No
-stomata occur on the upper surface. The under epidermis (2) with
-numerous stomata, is surrounded by the characteristic guard cells.
-The end walls are beaded as on the upper surface. The palisade cells
-(3) appear as in the cross-section. The conducting cells (4 and 4)
-are of the spiral and pitted type. The papillæ (5 and 5) are very
-abundant in the powder and very characteristic. The fragments of the
-epidermis (6) are also abundant. The mesophyll (7) is characteristic,
-as it retains its form when powdered. The fibres (8) are usually
-associated with the conducting cells; occasionally they are found
-free as in the illustration.
-
-[Illustration: PLATE 109
-
-                         POWDERED KLIP BUCHU
-
-  1. Upper epidermis. 2. Under epidermis. 3. Palisade cells with
-  chlorophyll. 4 and 4. Conducting cells. 5 and 5. Papillæ. 6.
-  Fragments of the epidermis. 7. Mesophyll. 8. Fibres.]
-
-
-                           MOUNTAIN LAUREL
-
-=Epidermis.= The epidermal cells of mountain laurel are occasionally
-modified, as unicellular hairs (Plate 110, Fig. 1), particularly in
-the region of the veins. The ordinary epidermal cells have thick
-outer walls and thin inner walls. Beneath many of the epidermal cells
-are large air-spaces.
-
-=Upper Palisade Parenchyma.= The palisade parenchyma vary from four
-to five layers. The inner palisade cells are shorter and broader than
-the outer layer of cells.
-
-=Parenchyma.= The parenchyma cells (Fig. 4) are rounded in form
-and they are arranged in the form of columns which are one cell in
-thickness above, but two to three cells in thickness near the under
-epidermis. Between each chain of cells is a larger intercellular
-space (Fig. 6). In a few of the cells are large rosette crystals.
-
-=Under Epidermis.= The under epidermal cells are uniformly smaller
-than the upper epidermal cells.
-
-It is thus seen that mountain laurel leaf has no hypodermal cells;
-no spongy parenchyma; no under palisade cells; no under hypodermal
-cells, and no secretion cavities.
-
-
-                          TRAILING ARBUTUS
-
-=Epidermis.= The epidermal cells of the trailing arbutus (Plate 111,
-Fig. 2) are variable in size. Many of the cells are modified, as
-guard cells (Fig. 1).
-
-=Parenchyma.= The parenchyma cells are round and they are compactly
-arranged (Fig. 3) on the upper side of the leaf, but on the under
-side they are arranged in round, small, intercellular spaces (Fig.
-5). In some of the intercellular spaces are rosette crystals (Fig. 7).
-
-=Under Epidermis.= The under epidermal cells are smaller than the
-upper epidermal cells.
-
-It will be seen that the structure of trailing arbutus leaf is very
-simple and that its structure is different from that of klip buchu
-and mountain laurel.
-
-The structure of powdered leaves is very variable, yet characteristic
-for a given species. The leaves from the insect flower plant are
-collected with the stems, and ground and sold as a substitute for
-insect flowers. These leaves, when powdered, show the following
-structure (Plate 112):
-
-[Illustration: PLATE 110
-
-       CROSS-SECTION MOUNTAIN LAUREL (_Kalmia latifolia_, L.)
-
-  1. Hair. 2. Epidermis. 3. Palisade parenchyma. 4. Parenchyma. 5.
-  Under epidermis. 6. Intercellular space. 7. Rosette crystal. 8.
-  Chlorophyll.]
-
-[Illustration: PLATE 111
-
-      CROSS-SECTION TRAILING ARBUTUS LEAF (_Epigæa repens_, L.)
-
-  1. Stomata. 2. Epidermis. 3. Parenchyma. 4. Cell with chlorophyll.
-  5. Intercellular space. 6. Under epidermis. 7. Rosette crystal.]
-
-Both the upper and lower epidermis have stomata (Figs. 1 and 2), but
-they differ in that the surrounding cells of the upper epidermis
-are wavy, while the corresponding cells of the under epidermis are
-similar, though the under epidermis has many attached hairs (Figs.
-3 and 4). The T-shaped hairs form the most abundant element of the
-powder. They are similar in structure to those found on the scales
-and stem. Fragments of the mesophyll have round cells and contain
-chlorophyll (Fig. 6). The conducting cells are spiral or reticulate.
-
-The different cells of the leaf differ greatly in structure, in
-amount, and in arrangement. In uva-ursi, boldus, pilocarpus,
-eucalyptus, and chimaphila leaves the outer walls of the epidermal
-cell is very thick. In uva-ursi leaves this thick wall appears bluish
-green when viewed under low power of the microscope.
-
-In belladonna, stramonium, henbane, peppermint, spearmint, digitalis,
-and horehound, the outer wall of the epidermal cells is thin.
-
-In witch-hazel, stramonium, coca, phytolacca, and peppermint there is
-a single layer of palisade parenchyma on the upper surface only of
-the leaf.
-
-In senna there is one layer of palisade parenchyma on the upper and
-one layer on the under side of the leaf. In matico and tea leaves
-there are two layers of spongy parenchyma on the upper side of the
-leaf.
-
-In chestnut leaves there are three layers of palisade parenchyma on
-the upper side of the leaf.
-
-In eucalyptus leaves the entire central part of the leaf, with the
-exception of the secretion cells and fibro-vascular bundle, is made
-up of the palisade parenchyma.
-
-In some leaves no palisade parenchyma occurs. Trailing arbutus (Plate
-111) is an example of such a leaf.
-
-In stramonium leaves the spongy parenchyma is strongly branched; in
-mountain laurel the spongy parenchyma is mostly non-branched and
-circular in form, as in trailing arbutus (Plate 111, Fig. 3), and as
-occurs in the midrib portion of most leaves.
-
-[Illustration: PLATE 112
-
-                    POWDERED INSECT FLOWER LEAVES
-           (_Chrysanthemum cinerariifolium_ [Trev.], Vis.)
-
-  1. Upper epidermis. 2. Under epidermis showing stoma and hair
-  scar. 3. Cross-section of under epidermis with attached hair. 4.
-  Cross-section of upper epidermis. 5. Hairs. 6. Mesophyll with
-  chlorophyll bodies. 7. Conducting cells.]
-
-In stramonium and chestnut are found rosette crystals. In henbane,
-coca, and senna are found prisms. In belladonna, scapola, and
-tobacco leaves are found micro-crystals. In most leaves no crystals
-occur. In witch-hazel and tea leaves stone cells occur, but in most
-leaves there are no stone cells. In eucalyptus, thyme, jaborandi,
-buchu, rosemary, and white pine leaves are secretion cells; while
-in belladonna, stramonium cells occur. In senna and coca leaves are
-crystal-bearing fibres; most leaves do not have crystal-bearing
-fibres.
-
-In chimaphila and uva-ursi there are no outgrowths from the epidermal
-cells.
-
-In senna, witch-hazel, chestnut, and coca, numerous non-glandular
-hairs occur on the epidermis. In tobacco, belladonna, henbane,
-pennyroyal, peppermint, and spearmint both glandular and
-non-glandular hairs occur on the epidermis.
-
-When studying leaves there should be considered the absence or
-presence of outgrowths and their nature; the nature of the epidermis
-and, when present, the number of layers of the hypodermis; the nature
-of the stoma, whether raised above, even with, or below the level
-of the epidermis; the number of layers, and the distribution, when
-present, of the palisade parenchyma; the form and amount of the
-spongy parenchyma; the absence or presence of secretion cells; the
-nature and form of the fibro-vascular bundles, and the nature and
-amount of the organic and inorganic cell contents.
-
-
-
-
-                             CHAPTER VII
-
-                               FLOWERS
-
-
-The histological structure of flowers is readily seen in the powder;
-therefore, in studying flowers, it is not necessary to section
-the various parts. Each part of the flower should be isolated and
-powdered separately and each separated part studied. In each case
-the powders will contain surface, cross-, and radial sections of the
-parts powdered. While studying flowers, special attention should be
-given to the pollen grains, to the papillæ of the petals, to the
-papillæ of the stigma, and, in certain flowers, to the style tissue.
-In the composite flowers special attention should also be given to
-the involucre scales, to the scales of receptacle, and, when present,
-to the pappus. In addition, attention must be given to secretion
-cavities, as in cloves.
-
-
-                            POLLEN GRAINS
-
-Pollen grains are one of the most characteristic elements found in
-powdered flowers, because they are so small that they are not broken
-up when the drug is milled.
-
-The two principal groups of pollen grains are, first, those with
-non-spiny walls (Plate 113); and, secondly, those with spiny walls
-(Plate 114), as shown in the two charts.
-
-In lavender flowers the pollen grains have six constrictions of the
-outer wall. This wall is slightly striated and the cell contents are
-granular.
-
-In clover flowers the pollen grains are mostly rounded in outline,
-the wall is uniformly thickened, and cell contents are coarsely
-granular.
-
-In belladonna flowers the pollen grains terminate in three blunt
-points.
-
-In Spanish saffron the pollen grains are spherical and the cell
-contents are granular.
-
-[Illustration: PLATE 113
-
-                     SMOOTH-WALLED POLLEN GRAINS
-
-  1. Cloves (_Eugenia caryophyllata_, Thunb.). 2. Santonica
-  (_Artemisia pauciflora_, Weber). 3. Elder (_Sambucus canadensis_,
-  L.). 4. Century minor (_Erythræa centaurium_ [L.], Pers.). 5. Pichi
-  (_Fabiana imbricata_, R. and P.). 6. Cyani. 7. Lavender (_Lavandula
-  officinalis_, Chaix.). 8. Clover (_Trifolium pratense_, L.). 9.
-  Belladonna (_Atropa belladonna_, L.). 10. Spanish saffron (_Crocus
-  sativus_, L.).]
-
-[Illustration: PLATE 114
-
-                     SPINY WALLED POLLEN GRAINS
-
-  1. Anthemis (_Anthemis nobilis_, L.).
-  2. Arnica (_Arnica montana_, L.).
-  3. Calendula (_Calendula officinalis_, L.).
-  4. Cassia flowers.
-  5. American saffron (_Carthamus tinctorius_, L.).
-  6. Blue malva flowers (_Malva sylvestris_, L.).]
-
-The non-spiny-walled pollen grains differ not only in microscopic
-appearance, but also in size. Clove pollen grains are the smallest,
-while Spanish saffron pollen grains are the largest.
-
-
-                   NON-SPINY-WALLED POLLEN GRAINS
-
-In cloves the pollen grains show a six-sided, angled cavity and an
-outer wall which terminates in three slightly pointed, narrowly
-notched portions, separated by nearly straight walls.
-
-In santonica the pollen grains have smooth, unequally thickened
-walls, which are strongly constricted at three points, the outline
-resembling three half-circles placed together.
-
-In elder flowers the pollen grains appear circular or three-parted.
-The wall is of nearly uniform thickness, even at the constricted part
-of the grain.
-
-In century minor the pollen grains show three pronounced
-restrictions. The wall at these points is very thin. In pichi
-flowers the pollen grains are either circular or three-sided and
-three-pointed. Inside of each point there is a nearly white pore. In
-some of the grains the pollen tube has grown out of one of the pores.
-
-In cyani flowers the pollen grains are longer than broad and the cell
-contents appear to be divided into two end portions and an elevated
-middle portion.
-
-
-                     SPINY-WALLED POLLEN GRAINS
-
-In anthemis the pollen grains have unequally thickened walls
-constricted in three places. The spines are short, broad at the base,
-and sharp-pointed.
-
-In arnica flowers the pollen grains show three light-colored pores
-and numerous short spines.
-
-In calendula flowers the pollen grains show one or more pores,
-typically three pores. These pores appear as white spots, and the
-wall immediately over the pore is smooth and thinner than the
-remaining part of the wall; the spines are very numerous.
-
-In cassia flower pollen grains the outer wall is extended into a
-number of rounded projections which are frequently arranged in sets
-of fours.
-
-In American saffron flowers the pollen grains show one, two, or three
-light-colored pores; the spines are short and broad.
-
-In blue malva flowers the pollen grains are spherical and the outer
-wall extends into numerous spinelike projections.
-
-It will be observed that the spiny-walled pollen grains differ
-greatly in size, the smallest being the pollen grain of anthemis and
-the largest being the pollen grain of blue malva flowers.
-
-In matricaria are numerous, greenish-brown, spiny-walled pollen
-grains. In anthemis are multicellular, uniseriate non-glandular hairs
-with three or four short, broad, yellow-walled basal cells and a
-greatly elongated, thin, gray-walled apical cell.
-
-In arnica are multiseriated branched hairs of the pappus, and
-numerous large, yellowish, spiny-walled pollen grains.
-
-
-                           STIGMA PAPILLÆ
-
-The =papillæ of the stigma= of most flowers form a characteristic
-element even when the flower is powdered. In the case of composite
-flowers the papillæ of the disk and ray flowers differ. In American
-saffron the papillæ of the style differ in a recognizable way from
-the papillæ of the stigma.
-
-The papillæ of the stigma of the ray and disk flowers of arnica,
-anthemis, matricaria, and insect flowers differ greatly. Even the
-papillæ of the stigma of the ray and disk flowers differ. In all
-cases observed the papillæ of the ray flowers are smaller than the
-papillæ of the disk flowers.
-
-The papillæ of the stigma of saffron (Plate 115, Fig. 3) are long and
-tubular. These papillæ are nearly uniform in diameter, and the apex
-is blunt and rounded. The wall is slightly granular in appearance.
-The papillæ of the stigma of American saffron (Plate 116, Fig. 2) are
-short and tubular. Each papilla is broadest at the base and tapers to
-a slender point. The papillæ of that part of the style which emerges
-from the corolla (Plate 116, Fig. 1) are large and curved, and the
-walls are very thick. The apex of the papilla is frequently solid.
-
-The papillæ of the stigma of the ray flowers of anthemis (Plate 117,
-Fig. 1) have thin, slightly striated walls; while the papillæ of the
-stigma of the disk flowers (Plate 117, Fig. 2) are longer, the walls
-are thicker, and the cell content is denser.
-
-[Illustration: PLATE 115
-
-                               PAPILLÆ
-
-  1. Arnica ray flowers (_Arnica montana_, L.).
-  2. Insect flower disk (_Chrysanthemum cinerariifolium_ [Trev.], Vis.).
-  3. True saffron (_Crocus sativus_, L.).]
-
-[Illustration: PLATE 116
-
-                         PAPILLÆ OF STIGMAS
-
-  1. Stigma papillæ of American saffron (_Carthamus tinctorius_, L.)
-  from that part of the style that emerges from the corolla.
-  2. Papillæ from the upper part of the stigma of American saffron.
-  3. Papillæ of the stigma of the disk flowers of arnica (_Arnica
-  montana_, L.).]
-
-[Illustration: PLATE 117
-
-                         PAPILLÆ OF STIGMAS
-
-  1. Stigma papillæ of the ligulate flowers of anthemis (_Anthemis
-  nobilis_, L.).
-  2. Stigma papillæ of the tubular flowers of anthemis.
-  3. Stigma papillæ of the ligulate flowers of matricaria
-  (_Matricaria chamomilla_, L.).
-  4. Stigma papillæ of the disk flowers of matricaria.
-  5. Stigma papillæ of the ligulate flowers of insect flower
-  (_Chrysanthemum cinerariifolium_ [Trev.], Vis.).]
-
-The papillæ of the stigma of the ray (Plate 117, Fig. 3) and disk
-flowers (Plate 117, Fig. 5) of matricaria are similar in structure,
-but the papillæ of the disk flowers are larger.
-
-The papillæ of the stigma of the ligulate flowers of insect flowers
-(Plate 117, Fig. 5) are tubular; the walls are striated, and in each
-papilla there is a small yellow globule, while the papillæ of the
-disk flowers (Plate 115, Fig. 2) are long and tubular, and the walls
-are thick.
-
-The papillæ of the stigma of the ray flowers of arnica (Plate 115,
-Fig. 1) are very short and tubular. The walls are thin and the cell
-contents appear as small, bright-yellow globules, while the papillæ
-of the stigma of the disk flowers (Plate 116, Fig. 3) are broadest at
-the base, the apex is pointed, and the yellow globules are larger.
-
-The =solitary= hairs are divided into the branched and non-branched
-hairs.
-
-
-                       POWDERED INSECT FLOWERS
-
-The microscopic examination of insect powder is difficult for the
-reason that there are so many elements to be constantly kept in mind.
-The parts of the flower which contribute characteristic cells are the
-stem, involucre, ray flowers, disk flowers, and the receptacle. In
-each of these parts there are many different types of cells.
-
-There are practically two types of flowers found in insect powder of
-commerce: first, closed or immature flowers, and secondly, open or
-mature flowers. As explained above, the half-open flowers consist
-largely of the two above-named varieties. Let us first consider the
-structure of the closed insect flowers as illustrated in Plate 118.
-
-[Illustration: PLATE 118
-
-                    POWDERED CLOSED INSECT FLOWER
-           (_Chrysanthemum cinerariifolium_, [Trev.] Vis.)
-
-  1. Edge of scale. 2. Fibre of scale. 3. Hairs. 4. Upper epidermis
-  of ray flower. 5. Under epidermis of ray flower. 6. Cross-section
-  of ray petal. 7. Parenchyma of ray flowers with crystals. 8. Lobe
-  of disk petal. 9. Filament tissue. 10. Calyx tissue, 11. Lobe of
-  stamen. 12. Pollen. 13. Papillæ of stigma. 14. Secretion cavity
-  with surrounding cells. 15. Parenchyma of the receptacle.]
-
-The involucre has many characteristic cells. The more prominent
-ones seen in the powder are the edge of the scale with the attached
-hair (Fig. 1). These hairs (Fig. 3) are T-shaped. The terminal cell
-is expanded laterally, and it terminates in two points. Connecting
-the terminal cell with the epidermis are two or three cells which
-are slightly longer than broad. In the powder the terminal cell is
-usually attached to fragments only of the supporting cells. Fibres of
-the bracts have thick, wavy, porous walls, and they have a tendency
-to occur in masses. The upper epidermis (Fig. 4) of the ray-flower
-petal is prominently papillate. The under epidermis consists of
-wavy cells without papillæ. Another view of the papillæ is shown in
-Fig. 6. The parenchyma of the ray flowers (Fig. 7) contain cubical
-crystals. The lobe of the disk-flower petal (Fig. 8) is papillate at
-the end, the terminal cells have thick outer and thin inner walls.
-The filament tissue (Fig. 9) is composed of nearly square cells. The
-calyx tissue (Fig. 10) is made up of thin-walled cells with slightly
-papillate margins. The lobe of the stamen (Fig. 11) consists of
-nearly uniform epidermal cells which are in contact throughout their
-long diameter, while the hypodermal cells are thin-walled and angled.
-The pollen grains (Fig. 12) are dark yellowish green, thin, and the
-wall does not appear perforated by pores. The papillæ of the stigma
-(Fig. 13) are clustered, club-shaped, and nearly white in color. They
-are usually found detached in the powder. All parts of the pistil
-contain secreting cells, but the most conspicuous secreting cavities
-(Fig. 14) are those of the ovary. These cavities appear brownish in
-color and are surrounded by small cells which appear indistinct on
-account of the great number of superimposed cells. The parenchyma of
-the receptacle occurs in fragments which have strongly marked porous
-walls.
-
-
-                         OPEN INSECT FLOWERS
-
-Many of the structures of open insect flowers (Plate 119) are
-similar to those found in the closed flower. There is practically
-no difference in the edge of the scale (Fig. 1); or the fibre of
-the scale (Fig. 2); or the T-shaped hairs (Fig. 3); or the upper
-epidermis of the ray flower (Fig. 4); or the under epidermis of the
-ray flower (Fig. 5); or the cross-section of the ray petal (Fig.
-6); or the lobe of the disk petal (Fig. 7); or the filament tissue
-(Fig. 8); or the lobe of the stamen (Fig. 9); or the papillæ of
-the stigma (Fig. 12); or the parenchyma of the receptacle (Fig.
-15). The difference in structure is found, first, in the involucre
-scales, which are more fibrous than the scales of the closed flowers;
-secondly, in the pollen (Fig. 11), which is less abundant than in the
-closed flower; it is also lighter in color and usually shows the wall
-perforated by three pores; thirdly, the outer layers of the achene
-consist of thick, porous-walled stone cells (Fig. 13), which occur
-singly or in groups; fourthly, the secretion cavity is broader and
-darker in color (Fig. 14). These differences enable one at once to
-distinguish between the closed and open insect flowers. Now, since
-the half-closed flowers consist almost wholly of a mixture of equal
-parts of closed and open flowers, it follows that the elements of
-these two flowers will be mixed in about equal proportions. Thus
-we are able to distinguish microscopically the three commercial
-varieties of insect powder--namely, closed insect flowers, open
-insect flowers, and half-open insect flowers.
-
-[Illustration: PLATE 119
-
-                     POWDERED OPEN INSECT FLOWER
-           (_Chrysanthemum cinerariifolium_, [Trev.] Vis.)
-
-  1. Edge of involucre scale. 2. Fibres of involucre scale. 3.
-  Hairs. 4. Upper epidermis of ray flower. 5. Under epidermis of ray
-  flower. 6. Cross-section of ray petal. 7. Lobe of disk flower. 8.
-  Filament tissue. 9. Lobe of stamen. 10. Calyx tissue, 11. Pollen.
-  12. Papillæ of the stigma. 13. Stone cells from the achene and
-  cross-section of achene. 14. Secretion cavity with surrounding
-  cells. 15. Parenchyma of the receptacle.]
-
-Insect flowers are the most valuable vegetable insecticide known; yet
-much of its effectiveness is destroyed by the adulterants which are
-so readily identified by the compound microscope.
-
-
-                       POWDERED WHITE DAISIES
-
-A common adulterant found in open insect flowers is the flower-heads
-of European daisy (_C. leucanthemum_). Examination of powdered
-flowers exported from Europe shows that the entire flower-head is
-ground and mixed with the insect flowers. In the cheaper varieties
-of open flowers, only the tubular flowers are added after they have
-been separated from the heads by crushing and sifting. These tubular
-flowers so closely resemble the tubular flowers of the true insect
-flowers that it is practically impossible to distinguish between them
-macroscopically. The quickest and surest way to identify them is
-to reduce a portion of the flowers to a fine powder and examine it
-microscopically.
-
-Certain structures of the white daisies (Plate 120) are somewhat
-similar to those found in insect flowers. These structures are the
-papillæ of the ray petal (Figs. 3, 5, and 13), the lobe of the disk
-petal (Fig. 14), and the lobe of the stamen and the pollen (Fig. 8).
-
-The differences are as follows: The under epidermis of the ray
-flowers is composed of wavy cells which are more elongated than the
-ray flowers of the under epidermis of the ray petal of insect flower.
-The filament tissue is made up of slightly beaded cells instead of
-smooth-walled cells. The papillæ of the stigma are smaller than the
-papillæ of insect flowers. The most striking difference is found
-in the structure of the achene. The epidermal tissue of the achene
-is composed of palisade cells (Fig. 10), which in the mature form
-have thick white walls and scarcely any cavity. These cells swell
-perceptibly when placed in water. The other striking feature of the
-achene is the bright red resin masses which occur free in the field.
-Even a small trace of daisies in insect powder can be identified.
-
-[Illustration: PLATE 120
-
-      POWDERED WHITE DAISIES (_Chrysanthemum leucanthemum_, L.)
-
-  1 and 2. Scale tissue. 3, 5 and 13. Papillæ of petals. 4. Scale
-  tissue. 6. Lobe of ray petal. 7. Filament tissue. 8. Pollen. 9.
-  Papillæ of stigma. 10. Palisade cells of achene. 11. Resin masses.
-  12. Parenchyma of receptacle. 14. Lobe of dish petal.]
-
-When studying flowers there should be considered the number and
-structure of pollen grains; the nature of the papillæ of the stigma
-and the petals; the nature of the hairs of the corolla and calyx,
-when present. In the composite flowers we should also consider the
-structure of the involucre scales, and, when present, the structure
-of the receptacle scales, as in the case of anthemus, and of the
-pappus hairs, as in the flowers of arnica, boneset, grindelia, and
-aromatic goldenrod.
-
-
-
-
-                            CHAPTER VIII
-
-                               FRUITS
-
-There is great variation in the structure of fruits, such a
-variation, in fact, that no one fruit has a structure typical of all
-the other fruits. Each fruit, however, has a pericarp and one or more
-seeds. The amount and structure of the cells forming the pericarp
-and the seeds of fruits differ in different fruits, but for each
-fruit there is a normal amount of, and a characteristic, cellular
-structure. Nearly all the important medicinal fruits are cremocarps
-or umbelliferous fruits.
-
-The plan of structure of cremocarps is similar, but they all have a
-different cellular structure. The epidermis may be simple or modified
-as papillæ or hairs. The secretion cavities may be absent (conium),
-or, when present, variable in number--cultivated celery seed has six,
-wild celery seed up to twelve, and anise up to twenty. The vascular
-bundles may be large or small. The endocarp cells may be two or more
-layers in thickness. The spermoderm may be thin or thick.
-
-The endosperm cells may vary in size and the cell contents may vary.
-
-
-                            CELERY FRUIT
-
-The fruit of celery (Plate 121), like other umbelliferous fruits, is
-composed of the pericarp and the seed.
-
-The pericarp is composed of epicarp cells, mesocarp cells, endocarp
-cells, and in each rib a vascular bundle. The seed is composed of
-the spermoderm, endosperm, and embryo. Each of these parts has a
-characteristic structure.
-
-=Epicarp=. The cells of the epicarp (Fig. 1) are papillæ and the
-outer wall is striated. The papillæ do not show, however, unless
-the cell is cut across the centre, which is the point at which the
-papillæ are located.
-
-[Illustration: PLATE 121
-
-       CROSS-SECTION OF CELERY FRUIT (_Apium graveolens_, L.)
-
-  1. Epicarp. 2. Mesocarp. 3. Vascular bundle. 4. Endocarp. 5.
-  Spermoderm. 6. Endosperm. 7. Secretion cavity.]
-
-[Illustration: PLATE 122
-
-                     DIAGRAMMATIC DRAWING OF THE
-
-  1. Cross-section of wild celery seed (_Apium graveolens_, L.).
-  2. Cross-section of cultivated celery seed (_Apium graveolens_, L.).]
-
-=Mesocarp=. In the rib part of the mesocarp (Fig. 2) is a vascular
-bundle, and between the ribs one or more secretion cavities. The
-vascular bundles are small and are surrounded by irregular-shaped
-mesocarp cells.
-
-The =secretion cavities= (Fig. 7) are oval in form and the tissue
-bordering the cavity is reddish brown in color. The mesocarp cells
-around the secretion cavities are more elongated than the other
-mesocarp cells.
-
-=Endocarp=. The endocarp cells are three layers in thickness. These
-cells are elongated transversely (Fig. 4).
-
-=Spermoderm=. The cells of the spermoderm are indistinct, compressed,
-and dark brown in color (Fig. 5).
-
-=Endosperm=. The endosperm cells (Fig. 6) make up the greater part
-of the fruit. The walls which are common to two cells are thick,
-non-beaded, and non-pitted, and the cavities of the cells are filled
-with aleurone grains.
-
-=Embryo=. The embryo cells, which show only in certain sections, are
-similar to endosperm cells.
-
-In anise, hops, sumac, and cumin fruits are characteristic hairs.
-
-In star anise, sabal, allspice, cubeb, pepper, juniper, buckthorn,
-and phytolacca fruits are stone cells.
-
-In cubeb, pepper, and cardamon are characteristic masses of aggregate
-starch.
-
-In sabal, allspice, and juniper are characteristic secretion cells.
-
-In all the umbelliferous fruits, with the exception of conium, are
-yellow to brown secretion cavities.
-
-In cubeb and pepper is aggregate starch. Colocynth contains many
-single and double spiral vessels.
-
-Bitter orange contains solitary crystals and spongy parenchyma.
-
-When studying fruits we must consider the nature of the epicarp
-cells--whether simple or modified as papillæ or hairs; the form and
-structure of the mesocarp cells; the number, size, and structure of
-the vascular bundle; the size and number of the secretion cells or
-cavities; the number of layers and the structure of the endocarp
-cells; the number of layers of stone cells--when present; the color
-and width of the spermoderm layer; the structure and cell contents of
-the endosperm cells; the nature of the embryo cells, and the nature
-of the cell contents.
-
-
-
-
-                             CHAPTER IX
-
-                                SEEDS
-
-
-Seeds are very variable in structure, so much so, in fact, that
-scarcely any two seeds have a similar structure. It is necessary,
-therefore, when examining seeds, to compare the structure of the seed
-under examination with authentic plates or with the section of a
-genuine seed. The layers of the seed are the spermoderm, perisperm,
-endosperm, and embryo. In some seeds the spermoderm forms the greater
-part of the seed; in others the perisperm is greatest in amount;
-in still others the cotyledons make up most of the seed, as in the
-mustards. The cells forming these different layers differ in form,
-structure, and number; therefore it is not difficult to distinguish
-and to differentiate between the different seeds when viewed as a
-section or as a powder. Almond is studied because it has most of the
-layers and cells found in seeds.
-
-
-                             SPERMODERM
-
-The =spermoderm= is the thin, brown, granular-appearing skin of the
-almond. The layers of the spermoderm are the epidermis, the hypoderm,
-the middle layers, and the inner epidermis.
-
-The =epidermis= consists of radially elongated, thick-walled stone
-cells which occur alone or in groups of two or more, but seldom as
-a continuous layer. The upper or outer part of the stone cells is
-non-porous, but the inner walls are strongly porous (Plate 123, Fig.
-1).
-
-The =hypoderm=. The cells forming the hypoderm are compressed, the
-wall structure is practically indistinguishable, and the whole mass
-is reddish brown (Plate 123, Fig. 2).
-
-Occurring in this brown layer are several vascular bundles (Plate
-123, Fig. 3).
-
-[Illustration: PLATE 123
-
-                   CROSS-SECTION SWEET ALMOND SEED
-
-  1. Epidermis. 2. Hypoderm. 3. Vascular bundle. 4. Middle layer. 5.
-  Inner epidermis. 6. Endosperm. 7. Outer layer of the embryo. 8.
-  Inner layers of the embryo.]
-
-The =middle layers=. The cells forming the middle layers (Fig. 4)
-have thin, wavy, light-colored walls which are frequently compressed,
-and it is with much difficulty that their outlines are made out.
-
-The =inner epidermis=. The cells forming the inner epidermis are
-rectangular in form, and they contain reddish-brown cell contents
-(Plate 123, Fig. 5).
-
-
-                              ENDOSPERM
-
-The =endosperm=. The cells forming the endosperm are large,
-rectangular in outline, usually one layer thick, and they contain
-aleurone grains.
-
-
-                               EMBRYO
-
-The =embryo=. The cells forming the outer layer of the embryo are
-smaller than the inner layers, and they are immediately inward from
-the layer of endosperm cells (Plate 123, Fig. 7).
-
-The cells forming the greater part of the embryo are large, rounded,
-and they contain aleurone grains and fixed oil (Plate 123, Fig. 8).
-
-In white and black mustard are characteristic mucilage and palisade
-cells.
-
-In mix vomica, stropanthus, and St. Ignatius’s bean are
-characteristic hairs.
-
-In physostigma and kola are characteristic starch grains.
-
-In henbane, capsicum, stramonium, lobelia, and belladonna seeds are
-characteristic epidermal cells.
-
-In areca nut, colchicum, saw palmetto, and nux vomica are
-characteristic thick-walled, reserve cellulose cells.
-
-In cardamon seed are aggregate starch masses with irregular outlines.
-
-In bitter and sweet almond, linseed, pepo, and stropanthus are
-aleurone grains.
-
-In bitter and sweet almonds are stone cells.
-
-In linseed, quince seed, and in white and black mustard are epidermal
-cells with mucilaginous walls and contents, etc.
-
-
-
-
-                              CHAPTER X
-
-                   ARRANGEMENT OF VASCULAR BUNDLES
-
-
-Having familiarized ourselves with the different types of mechanical
-and conducting cells, we shall now consider the different ways
-in which these cells are associated to form the =vascular= and
-=fibro-vascular bundles=.
-
-The simplest form of the vascular bundle occurs in petals, floral
-bracts, and leaves. In these parts the vascular bundle is made up of
-conducting cells only.
-
-In the great majority of cases, however, the conducting cells are
-associated with mechanical cells to form the fibro-vascular bundle.
-
-The fibro-vascular bundle is made up of, first, the =phloem=,
-which consists of sieve tubes, companion cells, bast fibres, and
-parenchyma; secondly, of the =xylem=, composed of vessels and
-tracheids, wood fibres and wood parenchyma; thirdly, of medullary
-rays (restricted to certain types); and fourthly, of the bundle
-sheath (restricted to certain types).
-
-
-                   TYPES OF FIBRO-VASCULAR BUNDLES
-
-There are three well-defined types of the fibro-vascular bundle,
-namely, the =radial=, the =concentric=, and the =collateral= types.
-
-
-                       RADIAL VASCULAR BUNDLES
-
-The radial type of bundle is met with most frequently in
-monocotyledonous roots.
-
-In this form (Plate 114) the xylem forms radial bands of tissue
-which alternate with isolated groups of phloem. The space between
-the phloem and xylem is filled in with either parenchyma or fibres,
-or both. In some cases the vessels of the xylem meet in the centre
-of the root, while in other cases the centre of the stem is occupied
-by pith parenchyma. Each bundle is surrounded by parenchyma cells,
-and in iris, calamus, and veratrum, rhizomes, and endodermis,
-surrounds the bundles located in the centre of the stem, consisting
-of thin-walled (mechanical) cells.
-
-[Illustration: PLATE 124
-
-   CROSS-SECTION OF A RADIAL VASCULAR BUNDLE OF SKUNK CABBAGE ROOT
-                (_Symplocarpus fœtidus_ [L.], Nutt.)
-
-  1. Vessels.
-  2. Bundle sheath.
-  3. Parenchyma.
-  4. Sieve cells.]
-
-[Illustration: PLATE 125
-
-     CROSS-SECTION OF A PHLOEM-CENTRIC BUNDLE OF CALAMUS RHIZOME
-                       (_Acorus calamus_, L.)
-
-  1. Vessels.
-  2. Sieve cells.
-  3. Phloem parenchyma.
-  4. Parenchyma surrounding the bundles.]
-
-In sarsaparilla root, the pith is composed of thick-walled, porous
-pith parenchyma cells with starch. Outside the pith are arranged
-radial bands of oval vessels which decrease in size toward the
-periphery. Between the ends of these bands occur isolated groups of
-sieve cells.
-
-Surrounding the sieve cells and vessels are thick-walled, angled
-fibres.
-
-External to these cells is an endodermis composed of lignified
-brownish-colored cells one layer in thickness.
-
-
-                     CONCENTRIC VASCULAR BUNDLES
-
-There are two principal types of the concentric bundle, namely,
-xylem-centric, in which the xylem is centric and the phloem is
-peripheral, as in veratrum root; and phloem-centric (Plate 125), in
-which the phloem is centric and the xylem peripheral, as in calamus
-rhizome.
-
-
-                     COLLATERAL VASCULAR BUNDLES
-
-There are three types of collateral vascular bundles--namely, closed
-collateral, bi-collateral, and open collateral.
-
-In the closed collateral bundle the phloem and xylem are not
-separated by a cambium layer, and in many cases the bundle is
-surrounded by thick, angled walled fibres, as in palm stem. The term
-closed bundle refers to the fact that there is no cambium between the
-xylem and phloem, therefore the bundle is “closed” to further growth,
-and not to the fact that it is frequently surrounded by fibres which
-prevent further growth. In podophyllum stem (Plate 126) the xylem
-portion of the bundle faces the centre of the stem and the phloem
-portion of the bundle faces the epidermis. The xylem and phloem are
-separated by a cambium layer, and both are surrounded by thick-walled
-angled fibres which are the chief mechanical cells of the stem. This
-bundle is, in fact, mechanically closed, but not physiologically
-because a cambium is present.
-
-[Illustration: PLATE 126
-
-    CROSS-SECTION OF A CLOSED COLLATERAL BUNDLE OF MANDRAKE STEM
-                    (_Podophyllum peltatum_, L.)
-
-  1. Vessels.
-  2. Sieve cells.
-  3. Cambium.
-  4. Fibres.
-  5. Parenchyma.
-  6. Intercellular space.]
-
-[Illustration: PLATE 127
-
-    BI-COLLATERAL BUNDLE OF PUMPKIN STEM (_Curcurbita pepo_, L.)
-
-  1. Vessels.
-  2. Sieve tubes.]
-
-
-                   BI-COLLATERAL VASCULAR BUNDLES
-
-In the bi-collateral vascular bundle (Plate 127) the xylem is in
-between two groups of phloem--namely, an inner group and an outer
-group.
-
-In pumpkin stem a bundle occurs in each angle of the stem. The entire
-bundle is surrounded by parenchyma cells.
-
-In an individual bundle the xylem consists of large circular vessels
-and a phloem containing large sieve cells, many of which show the
-yellow porous sieve plates.
-
-
-                  OPEN COLLATERAL VASCULAR BUNDLES
-
-In the open collateral bundle (Plate 100) the xylem and phloem are
-separated by the cambium layer, which, through its divisions, causes
-the stem to increase in thickness each year. This type of bundle is
-characteristic of the stems and roots of dicotyledonous plants.
-
-The bi-collateral bundle occurs in many leaves. The xylem in such
-cases is central, the phloem strands occupying upper and lower
-peripheral positions.
-
-
-
-
-                                INDEX
-
-
-  Abbé condenser, illustration, 11
-
-  Absorption tissue, introduction, 121
-    tissue of leaves, 125
-
-  Aerating tissue, introduction, 151
-
-  Annular vessels, illustration of, 129
-
-
-  Bark, of white pine powdered, description of, 250
-    of white pine powdered, illustration of, 251
-    unrossed white pine, cross-section, illustration of, 249
-
-  Barks, description of, 248
-    diagnostic structures of, 253
-    structural variations of, 252
-
-  Base sledge microtome, 35
-    sledge microtome, illustration, 35
-
-  Bast fibres, 89
-    branched, 92
-    branched, illustrations, 95
-    crystal bearing, 90, 92
-    description of, 100
-    groups of, illustrations, 102
-    non-porous and non-striated, 96
-    non-porous and non-striated, illustrations, 101
-    non-porous and striated, 96
-    occurrence in powdered drugs, 103
-    of barks, illustrations, 91, 93, 94
-    of klip buchu leaf, 262
-    of ruellia rhizome, 226
-    of ruellia root, 223
-    of ruellia stem, 235
-    of spigelia stem, 235
-    porous and non-striated, illustrations, 98
-    porous and striated, 92
-    porous and striated, illustrations, 97
-    storage function of, 179
-    striated and non-porous, illustrations of, 99
-
-  Bi-collateral vascular bundles, description of, 298
-
-  Buchu stems, cross-section, illustration of, 243
-    cross-section, illustration of, 244
-    powdered, description of, 245
-    powdered, illustration of, 246
-
-
-  Cambium of pink root, 221
-    of ruellia rhizome, 226
-    of ruellia stem, 237
-    of spigelia rhizome, 223
-    of spigelia stem, 235
-
-  Camera lucida, 22
-    illustrations, 22
-
-  Care of microscope, 28
-
-  Celery fruit, diagrammatic drawing of, 287
-
-  Cell contents, 182
-    aleurone grains, 197
-    aleurone grains, description of, 198
-    aleurone grains, form of, 197
-    aleurone grains, structure of, 197
-    aleurone grains, tests for, 198
-    chlorophyll, 182
-    crystals, 200
-    crystals, composition of, 200
-    crystals, micro-, 200
-    crystals, raphides, 200
-    crystals, rosette, 200
-    crystals, solitary, variation of, 205
-    cystoliths, 210
-    cystoliths, forms of, 210
-    cystoliths, occurrence of, 215
-    cystoliths, tests for, 215
-    hesperidin, 196
-    hesperidin, test for, 196
-    inulin, 194
-    inulin, tests for, 194
-    leucoplastids, 183
-    mucilage, 194
-    mucilage associated with raphides, tests for, 194
-    mucilage, tests for, 194
-    organic, 182
-    starch grains, formation of, 183
-    starch grains, hilum nature of, 188
-    starch grains, hilum of, 185
-    starch grains, mounting of, 188
-    starch grains, occurrence of, 184
-    starch grains, outline of, 185
-    starch grains, size of, 185
-    starch grains, tests for, 188
-    tannin, 196
-    tannin, occurrence of, 196
-    tannin, test for, 197
-    volatile oil, test for, 196
-    volatile oils, 196
-
-  Cell division common to onion root, 56
-
-  Cell plate, 55
-
-  Cell sap, 53
-
-  Cell, typical, 53
-
-  Cell wall, 53
-
-  Chromatin, 54
-
-  Chromatin granules, 55
-
-  Chromatophores, 53
-
-  Chromosomes, 55
-
-  Closed collateral bundles of mandrake stem, cross-section
-        illustration of, 296
-
-  Collateral vascular bundles, 295
-
-  Collenchyma cells, composition of walls, 109
-    illustrations, 108
-    occurring in catnip and motherwort, illustrations, 107
-    of ruellia stem, 235
-    structure of, 106
-
-  Compound microscope, illustration, 10
-    microscope, mechanical parts of, 7, 8
-    microscope of Robert Hooke, illustration, 8
-    microscope, optical parts of, 9, 11, 12
-    microscopes, introduction, 7
-
-  Concentric vascular bundles, 295
-
-  Conducting tissue, introduction, 126
-
-  Cork cells, origin of, 88
-
-  Cortical parenchyma, conduction by, 147
-    of ruellia stem, 235
-
-  Cortex, of pink root, 219
-    of ruellia rhizome, 226
-    of ruellia root, 221
-    of ruellia stem, 235
-    of spigelia rhizome, 223
-    of spigelia stem, 233
-
-  Cover glasses, 43
-    illustrations, 44
-
-  Crystal cavities, 176
-    cells, storage function of, 179
-
-  Cutting sections, 31
-
-  Cystoliths, illustrations of, 214
-
-  Cytoplasm, 53
-
-
-  Daisies, white, powdered, description of, 282
-    illustration of, 283
-
-  Dissecting microscope, illustration, 5
-    needles, 46
-    needles, illustration, 46
-
-  Drawing apparatus, illustration, 23
-
-
-  Ectoplast, 53
-
-  Embryo, diagnostic structures of, 291
-
-  Endocarp of celery fruit, 288
-
-  Endodermal cells, illustrations of longitudinal sections, 119
-    illustrations of cross-sections, 117
-    introduction, 116
-    structure of, 116, 118
-
-  Endodermis, of klip buchu leaf, 262
-    of pink root, 219
-    of ruellia root, 223
-
-  Endosperm of celery fruit, 288
-    of seeds, 291
-
-  Epicarp of celery fruit, 285
-
-  Epidermal cells of leaves, storage function of, 179
-
-  Epidermis, surface deposits of, 62
-    of herbaceous stems, illustrations of, 152
-    of klip buchu leaf, 260
-    of leaves, illustrations of, 155
-    of mountain laurel, 264
-    of pink root, 219
-    of ruellia rhizome, 226
-    of ruellia root, 221
-    of ruellia stem, 235
-    of seeds, 289
-    of spigelia rhizome, 223
-    of spigelia stem, 233
-    of testa, 63
-
-  Epidermis of trailing arbutus, 264
-
-  Equatorial plane, 55
-    plate, 55
-
-
-  Fibro-vascular bundles, composition of, 292
-    of klip buchu leaf, 262
-    types of, 292
-
-  Flowers, diagnostic structures of, 284
-    parts of, 270
-
-  Folding magnifier, 4
-    illustration, 4
-
-  Fruits, cellular structure of, 285
-    diagnostic  characteristics of, 288
-    diagnostic structures of, 288
-
-
-  Glandular hairs of peppermint, 178
-    illustrations of, 165
-    multicellular, 164
-    multicellular, multiseriate stalked, 166
-    multicellular, multiseriate stalked, description of, 166
-    multicellular, multiseriate stalked, occurrence, 166
-    multicellular sessile, 164
-    multicellular stalked, 164
-    multicellular, uniseriate stalked, 164
-    stalked, illustrations of, 167
-    storage function of, 178
-    unicellular, 164
-    unicellular, multiseriate stalked, 164
-    unicellular sessile, 164
-    unicellular stalked, 164
-    unicellular, uniseriate stalked, 164
-
-  Glandular tissue, introduction, 164
-
-  Glass slides, 44
-    illustrations, 44
-
-  Greenough binocular microscope, 15
-    illustration, 15
-
-  Guard cells, 151
-
-
-  Hairs, multicellular, multicellular non-branched, illustration, 75
-    multicellular, multiseriate branched, of Shepherdia, 78
-    multicellular, multiseriate branched, 77, 82
-    multicellular, multiseriate branched, illustrations, 79, 81
-    multicellular, multiseriate non-branched, 74
-    multicellular, uniseriate branched, illustration, 76
-    multicellular, uniseriate non-branched, 72
-    multicellular, uniseriate non-branched, illustrations of, 73
-
-  Hand cylinder microtome, illustration, 34
-    microtome, 31
-    microtome, illustration, 31
-    table microtome, 34
-    table microtome, illustration, 34
-
-  Horehound, powdered, description of, 237
-    powdered, illustration of, 238
-    spurious, powdered, description of, 237
-    spurious, powdered, illustration of, 239
-
-  Hypoderm of seeds, 289
-
-  Hypodermal cells, of leaves, storage function of, 179
-    illustrations, 120
-    structure of, 118
-
-  Hypoderms, of klip buchu leaf, 260
-    of ruellia root, 221
-
-
-  Illumination for microscope, 26
-
-  Indirect cell division, 54, 55
-
-  Inner bark of white pine, 248
-    epidermis of seeds, 291
-
-  Insect flower leaves, powdered, illustrations of, 268
-    stems, description of, 241
-    stems, powdered, illustration of, 240
-
-  Insect flowers, closed, powdered, illustration of, 279
-    open, description of, 280
-    open, powdered, illustration of, 281
-    powdered, description of, 278
-
-  Intercellular spaces, 158
-    illustrations of, 160, 161
-
-  Internal phloem, of spigelia stem, 235
-
-  Inulin, illustrations of, 195
-
-
-  Karyokinesis, 54, 55
-
-  Klip buchu, cross-section, illustration of, 261
-    powdered, description of, 262
-    powdered, illustration of, 263
-
-
-  Labeling, 47
-
-  Latex cavities, 176
-    tube cavities, 176
-    tubes, 142, 144
-    tubes, illustration of, 145
-    vessels, illustrations of, 146
-
-  Leaf epidermis, 59
-    illustrations, 60, 61
-
-  Leaf parenchyma, conduction by, 150
-
-  Leaves, diagnostic structures of, 267
-    stomata, 260
-
-  Lenticel, illustration of cross-section, 159
-
-  Lenticels, ærating function of, 157
-    structure of, 158
-
-  Linin, 54
-
-  Long paraffin process, 29
-
-
-  Machine microtomes, 32
-
-  Measuring cylinder, 40
-    illustration, 40
-
-  Mechanical stage, 21
-    stage, illustration, 22
-    tissue, 89
-
-  Medullary ray, 139
-    bundle, 139
-    bundle in tangential-section of quassia wood, 258
-    cell, 141
-    cell, arrangement of, in the ray, 142
-    cell, structure of, 142
-    cells, in cross-section of quassia wood, 254
-    cells, in radial-section of quassia wood, 258
-    cells, in tangential-section of quassia wood, 258
-    cells, of ruellia stem, 237
-
-  Medullary rays, illustration of cross-sections of, 143
-    illustration of longitudinal section, 140
-    in cross-section of quassia wood, 254
-    in radial-section of quassia wood, 254
-    of pink root, 221
-    of ruellia rhizome, 227
-    of ruellia root, 223
-    of spigelia rhizome, 226
-    of white pine bark, 250
-
-  Mesocarp of celery fruit, 285
-
-  Method of mounting specimens, 41
-
-  Micro-crystals, illustrations of, 201
-    lamp, 27
-
-  Micrometer eye-pieces, 21
-    illustrations, 20, 21
-
-  Microphotographic apparatus, 24
-    illustration, 24
-
-  Microscope, how to use, 25
-
-  Microscopic measurements, 19
-
-  Microtome, care of, 36
-
-  Middle bark of white pine, 248
-    lamella, 55
-    layers of seeds, 291
-
-  Minor rotary microtome, 36
-    illustration, 36
-
-  Mountain laurel, cross-section, illustration of, 265
-
-  Mucilage cavities, 172, 176
-
-  Multicellular hair, 72
-
-
-  Nuclear membrane, 55
-    spindle, 55
-
-  Nucleoli, 55
-
-  Nucleus, 53
-
-
-  Objectives, illustrations, 11
-
-  Ocular micrometer, 19
-    illustration, 19
-
-  Oil cavities, occurrence, 178
-    of leaves, 178
-    of seeds, 178
-    unicellular, 172
-
-  Open collateral vascular bundles, description of, 298
-
-  Origin of multicellular plants, 57
-
-  Outer bark of white pine, 248
-
-
-  Palisade parenchyma, conduction by, 150
-
-  Papillæ, 67
-    illustrations of, 275
-    of stigmas, illustrations of, 276, 277
-    stigma, description of, 274
-
-  Paraffin, blocks, 31
-    embedding oven, illustration, 30
-
-  Parenchyma, aquatic plant, 150
-    cells of white pine, 248
-    conduction by, 144
-    cortical, illustrations of, 148
-    of mountain laurel, 264
-    of trailing arbutus, 264
-    pith, illustrations of, 149
-
-  Pericycle of pink root, 221
-    of ruellia root, 223
-
-  Periderm, 80
-    cork, 80
-    illustrations of, 86
-    of cascara sagrada, illustrations, 84
-    of white oak bark, illustration of, 87
-    parenchyma and stone cells, 85
-    stone cells, 85
-
-  Permanent mounts, 41
-
-  Pharmacognostic microscope, illustration, 12
-
-  Phloem, centric bundle of calamus, cross-section, illustration of,
-        294
-    of ruellia rhizome, 226
-    of ruellia stem, 235
-    of spigelia rhizome, 223
-    of spigelia stem, 233
-
-  Phloem parenchyma, conduction by, 150
-    of pink root, 221
-    of ruellia rhizome, 226
-    of ruellia root, 223
-    of ruellia stem, 235
-    of spigelia rhizome, 223
-    of spigelia stem, 235
-
-  Photosynthetic tissue, 163
-
-  Pink root, description of, 227
-
-  Pith parenchyma, conduction by, 147
-    of pink root, 221
-    of ruellia rhizome, 227
-    of ruellia root, 223
-    of ruellia stem, 237
-    of spigelia rhizome, 226
-    of spigelia stem, 235
-
-  Pitted vessels, with bordered pores, illustration of, 135
-    illustrations of, 134
-
-  Plant hairs, forms of, 67
-    introduction, 66
-
-  Polar caps, 55
-
-  Polarization microscope, 16
-    illustration, 16
-
-  Pollen grains, 270
-    non-spiny-walled, description of, 273
-    smooth-walled, illustrations of, 271
-    spiny-walled, description of, 273
-    spiny-walled, illustrations of, 272
-
-  Preparation of specimens for cutting, 28
-
-  Protoplast, 53
-
-
-  Quassia wood, cross-section, illustration of, 255
-    radial-section, illustration of, 257
-
-
-  Radial vascular bundles, 292
-    skunk cabbage root, cross-section, illustration of, 293
-
-  Raphides, illustrations of, 203
-
-  Reading glass, 4
-    illustration, 4
-
-  Reagent set, illustration, 39
-
-  Reagents, list of, 38
-
-  Research microscope, 13
-    illustration, 14
-
-  Reserve cellulose, illustrations of, 180-181
-
-  Reticulate vessels, illustrations of, 133
-
-  Root hairs, 121, 122, 125
-    illustration of, 123
-    illustration of fragments, 124
-
-  Roots and rhizomes, 219
-    diagnostic structures of, 227
-
-  Rosette and solitary crystals, illustrations of, 213
-    crystals, illustrations of, 204
-    crystals, inclosed, illustrations of, 206
-
-  Ruellia ciliosa, Pursh., powdered, illustration of, 229
-    ciliosa, Pursh., rhizome, cross-section, illustration of, 225
-    ciliosa, Pursh., stem, cross-section, illustration of, 236
-    root, description of, 227
-    root, illustration of, 222
-
-
-  Scalpels, 46
-    illustration, 47
-
-  Scissors, 46
-    illustration, 46
-
-  Sclariform vessels, illustrations of, 132
-
-  Seeds, parts of, 289
-
-  Secretion cavities, of celery fruit, 288
-    description of, 176
-    illustrations of, 169-171
-    introduction, 166
-    lysigenous, 168
-    schizogenous, 168
-    schizo-lysigenous, 168
-    unicellular, 168
-
-  Secretion cells, of klip buchu leaf, 262
-    of white pine, 248
-
-  Short paraffin process, 29
-
-  Sieve cells, of klip buchu leaf, 262
-    of pink root, 221
-    of ruellia rhizome, 226
-    of ruellia root, 223
-    of ruellia stem, 235
-    of spigelia stem, 235
-
-  Sieve plate, 138
-    illustration of, 137
-
-  Sieve tube, illustration of, 137
-    tubes, introduction, 136
-    tubes, structure, 136
-
-  Simple microscope, introduction, 3
-
-  Slide box, 48
-    box, illustration, 48
-    cabinet, 49
-    cabinet, illustration of, 49
-    forceps, 45
-    forceps, illustrations, 45
-    tray, 48
-    tray, illustration, 48
-
-  Solitary crystals, illustrations of, 207-209, 211, 212
-    unicellular hairs, 69
-
-  Special research microscope, 14
-    illustration, 14
-
-  Specimens, preservation of, 48
-
-  Spermoderm, of celery fruit, 288
-    of seeds, 289
-
-  Spigelia marylandica, powdered, illustration of, 228
-    rhizome, cross-section, illustration of, 224
-    root, cross-section, illustration of, 220
-    stem, cross-section, illustration of, 234
-
-  Spindle fibres, 55
-
-  Spiral vessels, illustrations of, 129, 130
-
-  Spongy parenchyma of klip buchu, 260
-
-  Stage micrometer, 19
-    illustration, 19
-
-  Staining dish, 40
-    illustration, 40
-
-  Standardization of ocular micrometer, 19
-
-  Starch grains, illustrations of, 186, 187, 189-193
-
-  Steinheil lens, 5
-    illustration, 5
-
-  Stems, diagnostic structures of, 233
-    dicotyledonous, 233
-    herbaceous, 233
-    monocotyledonous, 233
-
-  Stomata, ærating function of, 151
-    illustrations of cross-section, 156
-    relation to surrounding cells, 154
-    types of, 153
-
-  Stone cells, of ruellia root, 223
-    branched, 109
-    branched, illustrations of, 110
-    description, in, 112
-    introduction, 109
-    occurrence, illustrations, 115
-    porous and non-striated, 111
-    porous and non-striated, illustrations of, 114
-    porous and striated, 109
-    porous and striated, illustrations of, 113
-    storage function of, 178
-
-  Storage cavities, 176
-    cavities, illustrations of, 177
-    cells, 173
-    cells, cortical parenchyma, 173
-    cells, illustrations of, 174
-    cells, pith parenchyma, 173
-    cells, wood parenchyma, 173
-    tissue, 173
-    walls, description of, 179
-
-  Stored mucilage and resin, illustrations of, 175
-
-  Surrounding cells, arrangement of, 154
-
-  Synthetic tissue, introduction, 163
-
-
-  Temporary mounts, 41
-
-  Testa cells, 65
-    epidermal cells, illustrations, 64
-
-  Tracheids of pink root, 221
-
-  Trailing arbutus leaf, cross-section, illustration of, 266
-
-  Tripod magnifier, 4
-    illustration, 4
-
-  Turntable, 46
-    illustration, 47
-
-
-  Under epidermis of klip buchu leaf, 262
-    epidermis of mountain laurel, 264
-    of trailing arbutus, 264
-    hypodermis of klip buchu leaf, 262
-    palisade parenchyma of klip buchu leaf, 262
-
-  Unicellular clustered hairs, 72
-    clustered hairs, illustrations, 71
-    non-glandular hairs, 69
-    solitary branched hairs, 72
-    solitary hairs, illustrations, 70
-
-  Upper palisade parenchyma of klip buchu leaf, 260
-    palisade parenchyma of mountain laurel, 264
-
-
-  Vacuoles, 53
-
-  Vascular bundles, arrangement of, 292
-    occurrence of, 292
-
-  Vessels, annular, 127
-    and tracheids, introduction, 126
-    in cross-section of quassia wood, 254
-    in radial-section of quassia wood, 254
-    in tangential-section of quassia wood, 258
-    of ruellia rhizome, 226
-    of ruellia root, 223
-    of ruellia stem, 237
-    of spigelia rhizome, 226
-    pitted, 131
-    pitted with bordered pores, 131
-    reticulate, 131
-    sclariform, 128
-    spiral, 127
-
-
-  Water pores, aerating function of, 151
-
-  Watchmaker’s loupe, 4
-    illustration, 4
-
-  Wood fibres, color of, 104
-    illustrations, 105
-    in cross-section of quassia wood, 254
-    in radial-section of quassia wood, 258
-    in tangential-section of quassia wood, 258
-    introduction, 104
-    structure of, 104
-
-  Wood parenchyma, conduction by, 150
-    in cross-section of quassia wood, 254
-    in radial-section of quassia wood, 258
-    of pink root, 221
-    of ruellia rhizome, 227
-    of ruellia root, 223
-    of ruellia stem, 237
-    of spigelia rhizome, 226
-    of spigelia stem, 235
-
-  Woods, description of, 254
-    diagnostic structures of, 258
-
-  Woody stems, buchu stem, description  of, 242
-    mature buchu stem, 242
-
-
-  Xylem, of pink root, 221
-    of ruellia rhizome, 226
-    of ruellia root, 223
-    of ruellia stem, 237
-    of spigelia rhizome, 226
-    of spigelia stem, 235
-
-
-
-
-                         Transcriber’s Notes
-
-  The Table of Illustrations at the beginning of the book was created
-  by the transcriber.
-
-  Inconsistencies in hyphenation such as
-  “extra-ordinary”/“extraordinary” have been maintained.
-
-  Minor punctuation and spelling errors have been silently corrected
-  and, except for those changes noted below, all misspellings in the
-  text, especially in dialogue, and inconsistent or archaic usage,
-  have been retained.
-
-  Page 53: “The outer portion of the nucelus” changed to “The outer
-  portion of the nucleus”.
-
-  Page 54: “the centre of the nucelus” changed to “the centre of the
-  nucleus”.
-
-  Page 62: “typical forms of arrangement of epidermal calls” changed
-  to “typical forms of arrangement of epidermal cells”.
-
-  Page 104: “of logwood and santalum rubum” changed to “of logwood
-  and santalum rubrum”.
-
-  Page 107: “the cross-section of catnip stem (_Nepeta cateria_”
-  changed to “the cross-section of catnip stem (_Nepeta cataria_”.
-
-  Page 120: “Cross-section sarsaparilla root (_Smilex officinalis_”
-  changed to “Cross-section sarsaparilla root (_Smilax officinalis_”.
-
-  Page 150: “cells are the narrowest parenchyma cells occuring”
-  changed to “cells are the narrowest parenchyma cells occurring”.
-
-  Page 155: “Upper epidermis of deer tongue (_Trilisia
-  odoratissima_” changed to “Upper epidermis of deer tongue
-  (_Trilisa odoratissima_”.
-
-  Page 171: “Parenchyma cells with protuding” changed to “Parenchyma
-  cells with protruding”.
-
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-
-<div style='text-align:center; font-size:1.2em; font-weight:bold'>The Project Gutenberg eBook of Histology of medicinal plants, by William Mansfield</div>
-
-<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>
-
-<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Title: Histology of medicinal plants</div>
-
-<div style='display:block; margin-top:1em; margin-bottom:1em; margin-left:2em; text-indent:-2em'>Author: William Mansfield</div>
-
-<div style='display:block; margin:1em 0'>Release Date: June 8, 2021 [eBook #65569]</div>
-
-<div style='display:block; margin:1em 0'>Language: English</div>
-
-<div style='display:block; margin:1em 0'>Character set encoding: UTF-8</div>
-
-<div style='display:block; margin-left:2em; text-indent:-2em'>Produced by: Peter Becker, Susan Carr and the Online Distributed Proofreading Team at https://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)</div>
-
-<div style='margin-top:2em; margin-bottom:4em'>*** START OF THE PROJECT GUTENBERG EBOOK HISTOLOGY OF MEDICINAL PLANTS ***</div>
-
-<div class="figcenter illowp53" id="cover" style="max-width: 44.4375em;">
-  <img class="w100" src="images/cover.jpg" alt="" />
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<h1 class="pg-brk">HISTOLOGY OF<br />
-MEDICINAL PLANTS</h1>
-
-<p class="pfs120">BY</p>
-
-<p class="pfs135">WILLIAM MANSFIELD, A.M., <span class="smcap">Phar.D.</span></p>
-
-<p class="pfs90">Professor of Histology and Pharmacognosy, College of<br />
-Pharmacy of the City of New York<br />
-Columbia University</p>
-
-<p class="center p6 pb6">TOTAL ISSUE, FOUR THOUSAND</p>
-
-<p class="pfs80">NEW YORK<br />
-JOHN WILEY &amp; SONS, <span class="smcap">Inc.</span><br />
-<span class="smcap">London</span>: CHAPMAN &amp; HALL, <span class="smcap">Limited</span></p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<p class="pfs90 p10 pb10 pg-brk">Copyright, 1916, by<br />
-WILLIAM MANSFIELD</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_iii">[Pg iii]</span></p>
-
-<h2 class="nobreak" id="PREFACE">PREFACE</h2>
-</div>
-
-<p>The object of the book is to provide a practical scientific
-course in vegetable histology for the use of teachers and students
-in schools and colleges.</p>
-
-<p>The medicinal plants are studied in great detail because
-they constitute one of the most important groups of economic
-plants. The cells found in these plants are typical of the cells
-occurring in the vegetable kingdom; therefore the book should
-prove a valuable text-book for all students of histology.</p>
-
-<p>The book contains much that is new. In Part II, which is
-devoted largely to the study of cells and cell contents, is a new
-scientific, yet practical, classification of cells and cell contents.
-The author believes that his classification of bast fibres and
-hairs will clear up much of the confusion that students have
-experienced when studying these structures.</p>
-
-<p>The book is replete with illustrations, all of which are from
-original drawings made by the author. As most of these illustrations
-are diagnostic of the plants in which they occur, they
-will prove especially valuable as reference plates.</p>
-
-<p>The material of the book is the outgrowth of the experience
-of the author in teaching histology at the College of Pharmacy
-of the City of New York, Columbia University, and of years
-of practical experience gained by examining powdered drugs in
-the laboratory of a large importing and exporting wholesale
-drug house.</p>
-
-<p>The author is indebted to Ernest Leitz and Bausch &amp;
-Lomb Optical Company for the use of cuts of microscopic
-apparatus used in Part I of the book.</p>
-
-<p>The author also desires to express his appreciation to Professor
-Walter S. Cameron, who has rendered him much valuable
-aid.</p>
-
-<p class="right"><span class="smcap">William Mansfield.</span></p>
-
-<p><span class="smcap">Columbia University</span>,<br />
-<span  class="pad2">September, 1916.</span></p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_v">[v]</span></p>
-
-<h2 class="nobreak" id="CONTENTS">CONTENTS</h2>
-</div>
-
-<table class="autotable fs90" width="95%" summary="">
-<tr>
-<td class="tdcp" colspan="2"><a href="#Part_I">PART I</a></td>
-</tr>
-<tr>
-<td class="tdc" colspan="2">SIMPLE AND COMPOUND MICROSCOPES AND MICROSCOPIC TECHNIC</td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_I">CHAPTER I</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">THE SIMPLE MICROSCOPES</td>
-</tr>
-<tr>
-<td class="tdl"></td>
-<td class="tdr fs70">PAGE</td>
-</tr>
-<tr>
-<td class="tdl">Simple microscopes, forms of</td>
-<td class="tdr"><a href="#Page_4">4</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_II">CHAPTER II</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">COMPOUND MICROSCOPES</td>
-</tr>
-<tr>
-<td class="tdl">Compound microscopes, structure of</td>
-<td class="tdr"><a href="#STRUCTURE_OF_THE_COMPOUND_MICROSCOPE">7</a></td>
-</tr>
-<tr>
-<td class="tdl">Compound microscopes, mechanical parts of</td>
-<td class="tdr"><a href="#THE_MECHANICAL_PARTS">7</a></td>
-</tr>
-<tr>
-<td class="tdl">Compound microscopes, optical parts of</td>
-<td class="tdr"><a href="#THE_OPTICAL_PARTS">9</a></td>
-</tr>
-<tr>
-<td class="tdl">Compound microscopes, forms of</td>
-<td class="tdr"><a href="#FORMS_OF_COMPOUND_MICROSCOPES">12</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_III">CHAPTER III</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">MICROSCOPIC MEASUREMENTS</td>
-</tr>
-<tr>
-<td class="tdl">Ocular micrometer</td>
-<td class="tdr"><a href="#OCULAR_MICROMETER">19</a></td>
-</tr>
-<tr>
-<td class="tdl">Stage micrometer</td>
-<td class="tdr"><a href="#STAGE_MICROMETER">19</a></td>
-</tr>
-<tr>
-<td class="tdl">Mechanical stage</td>
-<td class="tdr"><a href="#MECHANICAL_STAGES">21</a></td>
-</tr>
-<tr>
-<td class="tdl">Micrometer eye-pieces</td>
-<td class="tdr"><a href="#MICROMETER_EYE-PIECES">21</a></td>
-</tr>
-<tr>
-<td class="tdl">Camera lucida</td>
-<td class="tdr"><a href="#CAMERA_LUCIDA">22</a></td>
-</tr>
-<tr>
-<td class="tdl">Drawing apparatus</td>
-<td class="tdr"><a href="#DRAWING_APPARATUS">23</a></td>
-</tr>
-<tr>
-<td class="tdl">Microphotographic apparatus</td>
-<td class="tdr"><a href="#MICROPHOTOGRAPHIC_APPARATUS">24</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_IV">CHAPTER IV</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">HOW TO USE THE MICROSCOPE</td>
-</tr>
-<tr>
-<td class="tdl">Illumination</td>
-<td class="tdr"><a href="#ILLUMINATION">26</a></td>
-</tr>
-<tr>
-<td class="tdl">Micro lamp</td>
-<td class="tdr"><a href="#ARTIFICIAL_SOURCES">27</a></td>
-</tr>
-<tr>
-<td class="tdl">Care of the microscope</td>
-<td class="tdr"><a href="#CARE_OF_THE_MICROSCOPE">28</a></td>
-</tr>
-<tr>
-<td class="tdl">Preparation of specimens for cutting</td>
-<td class="tdr"><a href="#PREPARATION_OF_SPECIMENS_FOR_CUTTING">28</a></td>
-</tr>
-<tr>
-<td class="tdl">Paraffin imbedding oven<span class="pagenum" id="Page_vi">[vi]</span></td>
-<td class="tdr"><a href="#Page_30">30</a></td>
-</tr>
-<tr>
-<td class="tdl">Paraffin blocks</td>
-<td class="tdr"><a href="#fig32">31</a></td>
-</tr>
-<tr>
-<td class="tdl">Cutting sections</td>
-<td class="tdr"><a href="#CUTTING_SECTIONS">31</a></td>
-</tr>
-<tr>
-<td class="tdl">Hand microtome</td>
-<td class="tdr"><a href="#HAND_MICROTOME">31</a></td>
-</tr>
-<tr>
-<td class="tdl">Machine microtomes</td>
-<td class="tdr"><a href="#MACHINE_MICROTOMES">32</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_V">CHAPTER V</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">REAGENTS</td>
-</tr>
-<tr>
-<td class="tdl">Reagent set</td>
-<td class="tdr"><a href="#REAGENT_SET">39</a></td>
-</tr>
-<tr>
-<td class="tdl">Measuring cylinder</td>
-<td class="tdr"><a href="#MEASURING_CYLINDER">40</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#CHAPTER_VI">CHAPTER VI</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">HOW TO MOUNT SPECIMENS</td>
-</tr>
-<tr>
-<td class="tdl">Temporary mounts</td>
-<td class="tdr"><a href="#TEMPORARY_MOUNTS">41</a></td>
-</tr>
-<tr>
-<td class="tdl">Permanent mounts</td>
-<td class="tdr"><a href="#PERMANENT_MOUNTS">41</a></td>
-</tr>
-<tr>
-<td class="tdl">Cover glasses</td>
-<td class="tdr"><a href="#COVER_GLASSES">43</a></td>
-</tr>
-<tr>
-<td class="tdl">Glass slides</td>
-<td class="tdr"><a href="#GLASS_SLIDES">44</a></td>
-</tr>
-<tr>
-<td class="tdl">Forceps</td>
-<td class="tdr"><a href="#FORCEPS">45</a></td>
-</tr>
-<tr>
-<td class="tdl">Needles</td>
-<td class="tdr"><a href="#NEEDLES">46</a></td>
-</tr>
-<tr>
-<td class="tdl">Scissors</td>
-<td class="tdr"><a href="#SCISSORS">46</a></td>
-</tr>
-<tr>
-<td class="tdl">Turntable</td>
-<td class="tdr"><a href="#TURNTABLE">46</a></td>
-</tr>
-<tr>
-<td class="tdl">Labeling</td>
-<td class="tdr"><a href="#LABELING">47</a></td>
-</tr>
-<tr>
-<td class="tdl">Preservation of mounted specimens</td>
-<td class="tdr"><a href="#PRESERVATION_OF_MOUNTED_SPECIMENS">48</a></td>
-</tr>
-<tr>
-<td class="tdl">Slide box</td>
-<td class="tdr"><a href="#fig52">48</a></td>
-</tr>
-<tr>
-<td class="tdl">Slide tray</td>
-<td class="tdr"><a href="#fig53">48</a></td>
-</tr>
-<tr>
-<td class="tdl">Slide cabinet</td>
-<td class="tdr"><a href="#fig54">49</a></td>
-</tr>
-<tr>
-<td class="tdcp" colspan="2"><a href="#Part_II">PART II</a></td>
-</tr>
-<tr>
-<td class="tdc" colspan="2">TISSUES, CELLS AND CELL CONTENTS</td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_I">CHAPTER I</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">THE CELL</td>
-</tr>
-<tr>
-<td class="tdl">Typical cell</td>
-<td class="tdr"><a href="#TYPICAL_CELL">53</a></td>
-</tr>
-<tr>
-<td class="tdl">Changes in a cell undergoing division</td>
-<td class="tdr"><a href="#CHANGES_IN_A_CELL">55</a></td>
-</tr>
-<tr>
-<td class="tdl">Origin of multicellular plants</td>
-<td class="tdr"><a href="#ORIGIN_OF_MULTICELLULAR_PLANTS">57</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_II">CHAPTER II</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">THE EPIDERMIS AND PERIDERM</td>
-</tr>
-<tr>
-<td class="tdl">Leaf epidermis</td>
-<td class="tdr"><a href="#LEAF_EPIDERMIS">59</a></td>
-</tr>
-<tr>
-<td class="tdl">Testa epidermis</td>
-<td class="tdr"><a href="#TESTA_EPIDERMIS">63</a></td>
-</tr>
-<tr>
-<td class="tdl">Plant hairs</td>
-<td class="tdr"><a href="#PLANT_HAIRS">66</a></td>
-</tr>
-<tr>
-<td class="tdl">Forms of hairs<span class="pagenum" id="Page_vii">[vii]</span></td>
-<td class="tdr"><a href="#FORMS_OF_HAIRS">67</a></td>
-</tr>
-<tr>
-<td class="tdl">Papillæ</td>
-<td class="tdr"><a href="#PAPILLAE">67</a></td>
-</tr>
-<tr>
-<td class="tdl">Unicellular hairs</td>
-<td class="tdr"><a href="#UNICELLULAR_NON-GLANDULAR_HAIRS">69</a></td>
-</tr>
-<tr>
-<td class="tdl">Multicellular hairs</td>
-<td class="tdr"><a href="#MULTICELLULAR_HAIRS">72</a></td>
-</tr>
-<tr>
-<td class="tdl">Periderm</td>
-<td class="tdr"><a href="#PERIDERM">80</a></td>
-</tr>
-<tr>
-<td class="tdl">Cork periderm</td>
-<td class="tdr"><a href="#CORK_PERIDERM">80</a></td>
-</tr>
-<tr>
-<td class="tdl">Stone cell periderm</td>
-<td class="tdr"><a href="#STONE_CELL_PERIDERM">85</a></td>
-</tr>
-<tr>
-<td class="tdl">Parenchyma and stone cell periderm</td>
-<td class="tdr"><a href="#PARENCHYMA_AND_STONE_CELL_PERIDERM">85</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_III">CHAPTER III</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">MECHANICAL TISSUES</td>
-</tr>
-<tr>
-<td class="tdl">Bast fibres</td>
-<td class="tdr"><a href="#BAST_FIBRES">89</a></td>
-</tr>
-<tr>
-<td class="tdl">Crystal bearing bast fibres</td>
-<td class="tdr"><a href="#CRYSTAL-BEARING_BAST_FIBRES">90</a></td>
-</tr>
-<tr>
-<td class="tdl">Porous and striated bast fibres</td>
-<td class="tdr"><a href="#POROUS_AND_STRIATED_BAST_FIBRES">92</a></td>
-</tr>
-<tr>
-<td class="tdl">Porous and non-striated bast fibres</td>
-<td class="tdr"><a href="#POROUS_AND_NON-STRIATED_BAST_FIBRES">96</a></td>
-</tr>
-<tr>
-<td class="tdl">Non-porous and striated bast fibres</td>
-<td class="tdr"><a href="#NON-POROUS_AND_STRIATED_BAST_FIBRES">96</a></td>
-</tr>
-<tr>
-<td class="tdl">Non-porous and non-striated bast fibres</td>
-<td class="tdr"><a href="#NON-POROUS_AND_NON-STRIATED_BAST_FIBRES">96</a></td>
-</tr>
-<tr>
-<td class="tdl">Occurrence of bast fibres in powdered drugs</td>
-<td class="tdr"><a href="#OCCURRENCE_IN_POWDERED_DRUGS">103</a></td>
-</tr>
-<tr>
-<td class="tdl">Wood fibres</td>
-<td class="tdr"><a href="#WOOD_FIBRES">104</a></td>
-</tr>
-<tr>
-<td class="tdl">Collenchyma cells</td>
-<td class="tdr"><a href="#COLLENCHYMA_CELLS">106</a></td>
-</tr>
-<tr>
-<td class="tdl">Stone cells</td>
-<td class="tdr"><a href="#STONE_CELLS">109</a></td>
-</tr>
-<tr>
-<td class="tdl">Endodermal cells</td>
-<td class="tdr"><a href="#ENDODERMAL_CELLS">116</a></td>
-</tr>
-<tr>
-<td class="tdl">Hypodermal cells</td>
-<td class="tdr"><a href="#HYPODERMAL_CELLS">118</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_IV">CHAPTER IV</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">ABSORPTION TISSUE</td>
-</tr>
-<tr>
-<td class="tdl">Root hairs</td>
-<td class="tdr"><a href="#ROOT_HAIRS">121</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_V">CHAPTER V</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">CONDUCTING TISSUE</td>
-</tr>
-<tr>
-<td class="tdl">Vessels and tracheids</td>
-<td class="tdr"><a href="#VESSELS_AND_TRACHEIDS">126</a></td>
-</tr>
-<tr>
-<td class="tdl">Annular vessels</td>
-<td class="tdr"><a href="#ANNULAR_VESSELS">127</a></td>
-</tr>
-<tr>
-<td class="tdl">Spiral vessels</td>
-<td class="tdr"><a href="#SPIRAL_VESSELS">127</a></td>
-</tr>
-<tr>
-<td class="tdl">Sclariform vessels</td>
-<td class="tdr"><a href="#SCLARIFORM_VESSELS">128</a></td>
-</tr>
-<tr>
-<td class="tdl">Reticulate vessels</td>
-<td class="tdr"><a href="#RETICULATE_VESSELS">131</a></td>
-</tr>
-<tr>
-<td class="tdl">Pitted vessels</td>
-<td class="tdr"><a href="#PITTED_VESSELS">131</a></td>
-</tr>
-<tr>
-<td class="tdl">Pitted vessels with bordered pores</td>
-<td class="tdr"><a href="#PITTED_VESSELS_WITH_BORDERED_PORES">131</a></td>
-</tr>
-<tr>
-<td class="tdl">Sieve tubes</td>
-<td class="tdr"><a href="#SIEVE_TUBES">136</a></td>
-</tr>
-<tr>
-<td class="tdl">Sieve plate</td>
-<td class="tdr"><a href="#SIEVE_PLATE">138</a></td>
-</tr>
-<tr>
-<td class="tdl">Medullary bundles, rays and cells</td>
-<td class="tdr"><a href="#MEDULLARY_BUNDLES_RAYS_AND_CELLS">138</a></td>
-</tr>
-<tr>
-<td class="tdl">Medullary ray bundle</td>
-<td class="tdr"><a href="#THE_MEDULLARY_RAY_BUNDLE">139</a></td>
-</tr>
-<tr>
-<td class="tdl">The medullary ray</td>
-<td class="tdr"><a href="#THE_MEDULLARY_RAY">139</a></td>
-</tr>
-<tr>
-<td class="tdl">The medullary ray cell</td>
-<td class="tdr"><a href="#THE_MEDULLARY_RAY_CELL">141</a></td>
-</tr>
-<tr>
-<td class="tdl">Structure of the medullary ray cells<span class="pagenum" id="Page_viii">[viii]</span></td>
-<td class="tdr"><a href="#STRUCTURE_OF_CELLS">142</a></td>
-</tr>
-<tr>
-<td class="tdl">Arrangement of the medullary ray cells in the medullary ray</td>
-<td class="tdr"><a href="#ARRANGEMENT_OF_THE_CELLS_IN_A_RAY">142</a></td>
-</tr>
-<tr>
-<td class="tdl">Latex tubes</td>
-<td class="tdr"><a href="#LATEX_TUBES">142</a></td>
-</tr>
-<tr>
-<td class="tdl">Parenchyma</td>
-<td class="tdr"><a href="#PARENCHYMA">144</a></td>
-</tr>
-<tr>
-<td class="tdl">Cortical parenchyma</td>
-<td class="tdr"><a href="#CORTICAL_PARENCHYMA">147</a></td>
-</tr>
-<tr>
-<td class="tdl">Pith parenchyma</td>
-<td class="tdr"><a href="#PITH_PARENCHYMA">147</a></td>
-</tr>
-<tr>
-<td class="tdl">Leaf parenchyma</td>
-<td class="tdr"><a href="#LEAF_PARENCHYMA">150</a></td>
-</tr>
-<tr>
-<td class="tdl">Aquatic plant parenchyma</td>
-<td class="tdr"><a href="#AQUATIC_PLANT_PARENCHYMA">150</a></td>
-</tr>
-<tr>
-<td class="tdl">Wood parenchyma</td>
-<td class="tdr"><a href="#WOOD_PARENCHYMA">150</a></td>
-</tr>
-<tr>
-<td class="tdl">Phloem parenchyma</td>
-<td class="tdr"><a href="#PHLOEM_PARENCHYMA">150</a></td>
-</tr>
-<tr>
-<td class="tdl">Palisade parenchyma</td>
-<td class="tdr"><a href="#PALISADE_PARENCHYMA">150</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_VI">CHAPTER VI</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">AERATING TISSUE</td>
-</tr>
-<tr>
-<td class="tdl">Water pores</td>
-<td class="tdr"><a href="#WATER-PORES">151</a></td>
-</tr>
-<tr>
-<td class="tdl">Stomata</td>
-<td class="tdr"><a href="#STOMATA">151</a></td>
-</tr>
-<tr>
-<td class="tdl">Relation of stomata to the surrounding cells</td>
-<td class="tdr"><a href="#Page_154">154</a></td>
-</tr>
-<tr>
-<td class="tdl">Lenticels</td>
-<td class="tdr"><a href="#LENTICELS">157</a></td>
-</tr>
-<tr>
-<td class="tdl">Intercellular spaces</td>
-<td class="tdr"><a href="#Page_158">158</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_VII">CHAPTER VII</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">SYNTHETIC TISSUE</td>
-</tr>
-<tr>
-<td class="tdl">Photosynthetic tissue</td>
-<td class="tdr"><a href="#PHOTOSYNTHETIC_TISSUE">163</a></td>
-</tr>
-<tr>
-<td class="tdl">Glandular tissue</td>
-<td class="tdr"><a href="#GLANDULAR_TISSUE">164</a></td>
-</tr>
-<tr>
-<td class="tdl">Glandular hairs</td>
-<td class="tdr"><a href="#UNICELLULAR_GLANDULAR_HAIRS">164</a></td>
-</tr>
-<tr>
-<td class="tdl">Secretion cavities</td>
-<td class="tdr"><a href="#SECRETION_CAVITIES">166</a></td>
-</tr>
-<tr>
-<td class="tdl">Schizogenous cavities</td>
-<td class="tdr"><a href="#SCHIZOGENOUS_CAVITIES">168</a></td>
-</tr>
-<tr>
-<td class="tdl">Lysigenous cavities</td>
-<td class="tdr"><a href="#LYSIGENOUS_CAVITIES">168</a></td>
-</tr>
-<tr>
-<td class="tdl">Schizo-lysigenous cavities</td>
-<td class="tdr"><a href="#SCHIZO-LYSIGENOUS_CAVITIES">168</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_VIII">CHAPTER VIII</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">STORAGE TISSUE</td>
-</tr>
-<tr>
-<td class="tdl">Storage cells</td>
-<td class="tdr"><a href="#STORAGE_CELLS">173</a></td>
-</tr>
-<tr>
-<td class="tdl">Storage cavities</td>
-<td class="tdr"><a href="#STORAGE_CAVITIES">176</a></td>
-</tr>
-<tr>
-<td class="tdl">Crystal cavities</td>
-<td class="tdr"><a href="#CRYSTAL_CAVITIES">176</a></td>
-</tr>
-<tr>
-<td class="tdl">Mucilage cavities</td>
-<td class="tdr"><a href="#MUCILAGE_CAVITIES">176</a></td>
-</tr>
-<tr>
-<td class="tdl">Latex cavities</td>
-<td class="tdr"><a href="#LATEX_CAVITIES">176</a></td>
-</tr>
-<tr>
-<td class="tdl">Oil cavity</td>
-<td class="tdr"><a href="#OIL_CAVITY">178</a></td>
-</tr>
-<tr>
-<td class="tdl">Glandular hairs as storage organs</td>
-<td class="tdr"><a href="#GLANDULAR_HAIRS">178</a></td>
-</tr>
-<tr>
-<td class="tdl">Storage walls</td>
-<td class="tdr"><a href="#STORAGE_WALLS">179</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PII_CHAPTER_IX">CHAPTER IX</a><span class="pagenum" id="Page_ix">[ix]</span></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">CELL CONTENTS</td>
-</tr>
-<tr>
-<td class="tdl">Chlorophyll</td>
-<td class="tdr"><a href="#CHLOROPHYLL">182</a></td>
-</tr>
-<tr>
-<td class="tdl">Leucoplastids</td>
-<td class="tdr"><a href="#LEUCOPLASTIDS">183</a></td>
-</tr>
-<tr>
-<td class="tdl">Starch grains</td>
-<td class="tdr"><a href="#STARCH_GRAINS">183</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Occurrence</td>
-<td class="tdr"><a href="#OCCURRENCE">184</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Outline</td>
-<td class="tdr"><a href="#OUTLINE">185</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Size</td>
-<td class="tdr"><a href="#SIZE">185</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Hilum</td>
-<td class="tdr"><a href="#HILUM">185</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Nature of hilum</td>
-<td class="tdr"><a href="#NATURE_OF_THE_HILUM">188</a></td>
-</tr>
-<tr>
-<td class="tdl">Inulin</td>
-<td class="tdr"><a href="#INULIN">194</a></td>
-</tr>
-<tr>
-<td class="tdl">Mucilage</td>
-<td class="tdr"><a href="#MUCILAGE">194</a></td>
-</tr>
-<tr>
-<td class="tdl">Hesperidin</td>
-<td class="tdr"><a href="#HESPERIDIN">196</a></td>
-</tr>
-<tr>
-<td class="tdl">Volatile oil</td>
-<td class="tdr"><a href="#VOLATILE_OIL">196</a></td>
-</tr>
-<tr>
-<td class="tdl">Tannin</td>
-<td class="tdr"><a href="#TANNIN">196</a></td>
-</tr>
-<tr>
-<td class="tdl">Aleurone grains</td>
-<td class="tdr"><a href="#ALEURONE_GRAINS">197</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Structure of aleurone grains</td>
-<td class="tdr"><a href="#STRUCTURE_OF_ALEURONE_GRAINS">197</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Form of aleurone grains</td>
-<td class="tdr"><a href="#FORM_OF_ALEURONE_GRAINS">197</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Description of aleurone grains</td>
-<td class="tdr"><a href="#DESCRIPTION_OF_ALEURONE_GRAINS">198</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Tests for aleurone grains</td>
-<td class="tdr"><a href="#TESTS_FOR_ALEURONE_GRAINS">198</a></td>
-</tr>
-<tr>
-<td class="tdl">Crystals</td>
-<td class="tdr"><a href="#CRYSTALS">200</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Micro-crystals</td>
-<td class="tdr"><a href="#MICRO-CRYSTALS">200</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Raphides</td>
-<td class="tdr"><a href="#RAPHIDES">200</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Rosette crystals</td>
-<td class="tdr"><a href="#ROSETTE_CRYSTALS">202</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Solitary crystals</td>
-<td class="tdr"><a href="#SOLITARY_CRYSTALS">205</a></td>
-</tr>
-<tr>
-<td class="tdl">Cystoliths</td>
-<td class="tdr"><a href="#CYSTOLITHS">210</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Forms of cystoliths</td>
-<td class="tdr"><a href="#FORMS_OF_CYSTOLITHS">210</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Tests for cystoliths</td>
-<td class="tdr"><a href="#TESTS_FOR_CYSTOLITHS">215</a></td>
-</tr>
-<tr>
-<td class="tdcp" colspan="2"><a href="#Part_III">PART III</a></td>
-</tr>
-<tr>
-<td class="tdc" colspan="2">HISTOLOGY OF ROOTS, RHIZOMES, STEMS, BARKS, <br />WOODS, FLOWERS, FRUITS AND SEEDS</td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_I">CHAPTER I</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">ROOTS AND RHIZOMES</td>
-</tr>
-<tr>
-<td class="tdl">Cross-section of pink root</td>
-<td class="tdr"><a href="#CROSS-SECTION_PINK_ROOT">219</a></td>
-</tr>
-<tr>
-<td class="tdl">Cross-section of ruellia root</td>
-<td class="tdr"><a href="#CROSS-SECTION_RUELLIA_ROOT">219</a></td>
-</tr>
-<tr>
-<td class="tdl">Cross-section of spigelia rhizome</td>
-<td class="tdr"><a href="#CROSS-SECTION_SPIGELIA_RHIZOME">223</a></td>
-</tr>
-<tr>
-<td class="tdl">Cross-section of ruellia rhizome</td>
-<td class="tdr"><a href="#CROSS-SECTION_RUELLIA_RHIZOME">226</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Powdered pink root</td>
-<td class="tdr"><a href="#POWDERED_PINK_ROOT">227</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Powdered ruellia root</td>
-<td class="tdr"><a href="#POWDERED_RUELLIA_ROOT">227</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_II">CHAPTER II</a><span class="pagenum" id="Page_x">[x]</span></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">STEMS</td>
-</tr>
-<tr>
-<td class="tdl">Herbaceous stems</td>
-<td class="tdr"><a href="#HERBACEOUS_STEMS">233</a></td>
-</tr>
-<tr>
-<td class="tdl">Cross-section, spigelia stem</td>
-<td class="tdr"><a href="#CROSS-SECTION_SPIGELIA_STEM">233</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Ruellia stem</td>
-<td class="tdr"><a href="#RUELLIA_STEM">235</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Powdered horehound</td>
-<td class="tdr"><a href="#POWDERED_HOREHOUND">237</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered spurious horehound</td>
-<td class="tdr"><a href="#POWDERED_SPURIOUS_HOREHOUND">237</a></td>
-</tr>
-<tr>
-<td class="tdl pad3">Insect flower stems</td>
-<td class="tdr"><a href="#INSECT_FLOWER_STEMS">241</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_III">CHAPTER III</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">WOODY STEMS</td>
-</tr>
-<tr>
-<td class="tdl">Buchu stem</td>
-<td class="tdr"><a href="#BUCHU_STEM">242</a></td>
-</tr>
-<tr>
-<td class="tdl">Mature buchu stem</td>
-<td class="tdr"><a href="#MATURE_BUCHU_STEM">242</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered buchu stem</td>
-<td class="tdr"><a href="#POWDERED_BUCHU_STEM">245</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_IV">CHAPTER IV</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">BARKS</td>
-</tr>
-<tr>
-<td class="tdl">White pine bark</td>
-<td class="tdr"><a href="#WHITE_PINE_BARK">248</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered white pine bark</td>
-<td class="tdr"><a href="#POWDERED_WHITE_PINE_BARK">250</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_V">CHAPTER V</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">WOODS</td>
-</tr>
-<tr>
-<td class="tdl">Cross-section quassia</td>
-<td class="tdr"><a href="#CROSS-SECTION_QUASSIA">254</a></td>
-</tr>
-<tr>
-<td class="tdl">Radial-section quassia</td>
-<td class="tdr"><a href="#RADIAL_SECTION_QUASSIA">254</a></td>
-</tr>
-<tr>
-<td class="tdl">Tangential-section quassia</td>
-<td class="tdr"><a href="#TANGENTIAL_SECTION_QUASSIA">258</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_VI">CHAPTER VI</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">LEAVES</td>
-</tr>
-<tr>
-<td class="tdl">Klip buchu</td>
-<td class="tdr"><a href="#KLIP_BUCHU">260</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered klip buchu</td>
-<td class="tdr"><a href="#POWDERED_KLIP_BUCHU">262</a></td>
-</tr>
-<tr>
-<td class="tdl">Mountain laurel</td>
-<td class="tdr"><a href="#MOUNTAIN_LAUREL">264</a></td>
-</tr>
-<tr>
-<td class="tdl">Trailing arbutus</td>
-<td class="tdr"><a href="#TRAILING_ARBUTUS">264</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_VII">CHAPTER VII</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">FLOWERS</td>
-</tr>
-<tr>
-<td class="tdl">Pollen grains</td>
-<td class="tdr"><a href="#POLLEN_GRAINS">270</a></td>
-</tr>
-<tr>
-<td class="tdl">Non-spiny-walled pollen grains</td>
-<td class="tdr"><a href="#NON-SPINY-WALLED_POLLEN_GRAINS">273</a></td>
-</tr>
-<tr>
-<td class="tdl">Spiny-walled pollen grains</td>
-<td class="tdr"><a href="#SPINY-WALLED_POLLEN_GRAINS">273</a></td>
-</tr>
-<tr>
-<td class="tdl">Stigma papillæ</td>
-<td class="tdr"><a href="#STIGMA_PAPILL">274</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered insect flowers<span class="pagenum" id="Page_xi">[xi]</span></td>
-<td class="tdr"><a href="#POWDERED_INSECT_FLOWERS">278</a></td>
-</tr>
-<tr>
-<td class="tdl">Open insect flowers</td>
-<td class="tdr"><a href="#OPEN_INSECT_FLOWERS">280</a></td>
-</tr>
-<tr>
-<td class="tdl">Powdered white daisies</td>
-<td class="tdr"><a href="#POWDERED_WHITE_DAISIES">282</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_VIII">CHAPTER VIII</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">FRUITS</td>
-</tr>
-<tr>
-<td class="tdl">Celery fruit</td>
-<td class="tdr"><a href="#CELERY_FRUIT">285</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_IX">CHAPTER IX</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">SEEDS</td>
-</tr>
-<tr>
-<td class="tdl">Sweet almonds</td>
-<td class="tdr"><a href="#SPERMODERM">289</a></td>
-</tr>
-<tr>
-<td class="tdcc" colspan="2"><a href="#PIII_CHAPTER_X">CHAPTER X</a></td>
-</tr>
-<tr>
-<td class="tdcc2" colspan="2">ARRANGEMENT OF VASCULAR BUNDLES</td>
-</tr>
-<tr>
-<td class="tdl">Types of fibro-vascular bundles</td>
-<td class="tdr"><a href="#TYPES_OF_FIBRO-VASCULAR_BUNDLES">292</a></td>
-</tr>
-<tr>
-<td class="tdl">Radial vascular bundles</td>
-<td class="tdr"><a href="#RADIAL_VASCULAR_BUNDLES">292</a></td>
-</tr>
-<tr>
-<td class="tdl">Concentric vascular bundles</td>
-<td class="tdr"><a href="#CONCENTRIC_VASCULAR_BUNDLES">295</a></td>
-</tr>
-<tr>
-<td class="tdl">Collateral vascular bundles</td>
-<td class="tdr"><a href="#COLLATERAL_VASCULAR_BUNDLES">295</a></td>
-</tr>
-<tr>
-<td class="tdl">Bi-collateral vascular bundles</td>
-<td class="tdr"><a href="#BI-COLLATERAL_VASCULAR_BUNDLES">298</a></td>
-</tr>
-<tr>
-<td class="tdl">Open collateral vascular bundles</td>
-<td class="tdr"><a href="#OPEN_COLLATERAL_VASCULAR_BUNDLES">298</a></td>
-</tr>
-<tr>
-<td class="tdcp" colspan="2"><a href="#INDEX"><span class="fs100">INDEX</span></a></td>
-</tr>
-</table>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<h2 class="nobreak" id="TOI">TABLE OF ILLUSTRATIONS</h2>
-</div>
-
-<table class="autotable fs80" width="95%" summary="">
-<tr>
-<td class="tdl"></td>
-<td class="tdl"></td>
-<td class="tdr fs70">PAGE</td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;1.</td>
-<td class="tdl">Tripod Magnifier</td>
-<td class="tdr"><a href="#fig1-fig2">4</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;2.</td>
-<td class="tdl">Watchmaker’s Loupe</td>
-<td class="tdr"><a href="#fig1-fig2">4</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;3.</td>
-<td class="tdl">Folding Magnifier</td>
-<td class="tdr"><a href="#fig3-fig4">4</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;4.</td>
-<td class="tdl">Reading Glass</td>
-<td class="tdr"><a href="#fig3-fig4">4</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;5.</td>
-<td class="tdl">Steinheil Aplanatic Lens</td>
-<td class="tdr"><a href="#fig5">5</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;6.</td>
-<td class="tdl">Dissecting Microscope</td>
-<td class="tdr"><a href="#fig6">5</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;7.</td>
-<td class="tdl">Compound Microscope of Robert Hooke</td>
-<td class="tdr"><a href="#fig7">8</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;8.</td>
-<td class="tdl">Compound Microscope</td>
-<td class="tdr"><a href="#fig8">10</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> &nbsp;&nbsp;9.</td>
-<td class="tdl">Abbé Condenser</td>
-<td class="tdr"><a href="#fig9">11</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 10.</td>
-<td class="tdl"></td>
-<td class="tdr"><a href="#fig10-fig11-fig12">11</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 11.</td>
-<td class="tdl"></td>
-<td class="tdr"><a href="#fig10-fig11-fig12">11</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 12.</td>
-<td class="tdl">Objectives</td>
-<td class="tdr"><a href="#fig10-fig11-fig12">11</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 13.</td>
-<td class="tdl"></td>
-<td class="tdr"><a href="#fig13-fig14-fig15">12</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 14.</td>
-<td class="tdl"></td>
-<td class="tdr"><a href="#fig13-fig14-fig15">12</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 15.</td>
-<td class="tdl">Eye-Pieces.</td>
-<td class="tdr"><a href="#fig13-fig14-fig15">12</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 16.</td>
-<td class="tdl">Pharmacognostic Microscope</td>
-<td class="tdr"><a href="#fig16">12</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 17.</td>
-<td class="tdl">Research Microscope</td>
-<td class="tdr"><a href="#fig17-fig18">14</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 18.</td>
-<td class="tdl">Special Research Microscope</td>
-<td class="tdr"><a href="#fig17-fig18">14</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 19.</td>
-<td class="tdl">Greenough Binocular Microscope</td>
-<td class="tdr"><a href="#fig19">15</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 20.</td>
-<td class="tdl">Polarization Microscope</td>
-<td class="tdr"><a href="#fig20">16</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 21.</td>
-<td class="tdl">Ocular Micrometer</td>
-<td class="tdr"><a href="#fig21_22">19</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 22.</td>
-<td class="tdl">Stage Micrometer</td>
-<td class="tdr"><a href="#fig21_22">19</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 23.</td>
-<td class="tdl">Micrometer Eye-Piece</td>
-<td class="tdr"><a href="#fig23">20</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 24.</td>
-<td class="tdl">Micrometer Eye-Piece</td>
-<td class="tdr"><a href="#fig24">21</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 25.</td>
-<td class="tdl">Mechanical Stage</td>
-<td class="tdr"><a href="#fig25-fig26">22</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 26.</td>
-<td class="tdl">Camera Lucida</td>
-<td class="tdr"><a href="#fig25-fig26">22</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 27.</td>
-<td class="tdl">Camera Lucida</td>
-<td class="tdr"><a href="#fig25_27-b">22</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 28.</td>
-<td class="tdl">Drawing Apparatus</td>
-<td class="tdr"><a href="#fig28">23</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 29.</td>
-<td class="tdl">Microphotographic Apparatus</td>
-<td class="tdr"><a href="#fig29">24</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 30.</td>
-<td class="tdl">Micro Lamp</td>
-<td class="tdr"><a href="#fig30">27</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 31.</td>
-<td class="tdl">Paraffin-embedding Oven</td>
-<td class="tdr"><a href="#fig31">30</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 32.</td>
-<td class="tdl">Paraffin Blocks</td>
-<td class="tdr"><a href="#fig32">31</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 33.</td>
-<td class="tdl">Hand Microtome</td>
-<td class="tdr"><a href="#fig33">31</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 34.</td>
-<td class="tdl">Hand Cylinder Microtome</td>
-<td class="tdr"><a href="#fig34_35-t">34</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 35.</td>
-<td class="tdl">Hand Table Microtome</td>
-<td class="tdr"><a href="#fig34_35-b">34</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 36.</td>
-<td class="tdl">Base Sledge Microtome</td>
-<td class="tdr"><a href="#fig36">35</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 37.</td>
-<td class="tdl">Minot Rotary Microtome</td>
-<td class="tdr"><a href="#fig37">36</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 38.</td>
-<td class="tdl">Reagent Set</td>
-<td class="tdr"><a href="#fig38">39</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 39.</td>
-<td class="tdl">Measuring Cylinder</td>
-<td class="tdr"><a href="#fig39-fig40">40</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 40.</td>
-<td class="tdl">Staining Dish</td>
-<td class="tdr"><a href="#fig39-fig40">40</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 41.</td>
-<td class="tdl">Round Cover Glass</td>
-<td class="tdr"><a href="#fig41_43">44</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 42.</td>
-<td class="tdl">Square Cover Glass</td>
-<td class="tdr"><a href="#fig41_43">44</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 43.</td>
-<td class="tdl">Rectangular Cover Glass</td>
-<td class="tdr"><a href="#fig41_43">44</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 44.</td>
-<td class="tdl">Glass Slide</td>
-<td class="tdr"><a href="#fig44">44</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 45.</td>
-<td class="tdl">Histological Forceps</td>
-<td class="tdr"><a href="#fig45">45</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 46.</td>
-<td class="tdl">Forceps</td>
-<td class="tdr"><a href="#fig46">45</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 47.</td>
-<td class="tdl">Sliding-pin Forceps</td>
-<td class="tdr"><a href="#fig47">45</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 48.</td>
-<td class="tdl">Dissecting Needle</td>
-<td class="tdr"><a href="#fig48">46</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 49.</td>
-<td class="tdl">Scissors</td>
-<td class="tdr"><a href="#fig49">46</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 50.</td>
-<td class="tdl">Scalpels</td>
-<td class="tdr"><a href="#fig50">47</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 51.</td>
-<td class="tdl">Turntable</td>
-<td class="tdr"><a href="#fig51">47</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 52.</td>
-<td class="tdl">Slide Box</td>
-<td class="tdr"><a href="#fig52">48</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 53.</td>
-<td class="tdl">Slide Tray</td>
-<td class="tdr"><a href="#fig53">48</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Fig.</span> 54.</td>
-<td class="tdl">Slide Cabinet</td>
-<td class="tdr"><a href="#fig54">49</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">1</span></td>
-<td class="tdl"><span class="smcap">The Onion Root</span></td>
-<td class="tdr"><a href="#plate1">56</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">2</span></td>
-<td class="tdl"><span class="smcap">Leaf Epidermis</span></td>
-<td class="tdr"><a href="#plate2">60</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">3</span></td>
-<td class="tdl"><span class="smcap">Leaf Epidermis</span></td>
-<td class="tdr"><a href="#plate3">61</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">4</span></td>
-<td class="tdl"><span class="smcap">Testa Epidermal Cells</span></td>
-<td class="tdr"><a href="#plate4">64</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">5</span></td>
-<td class="tdl"><span class="smcap">Testa Cells</span></td>
-<td class="tdr"><a href="#plate5">65</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">6</span></td>
-<td class="tdl"><span class="smcap">Papillæ</span></td>
-<td class="tdr"><a href="#plate6">68</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">7</span></td>
-<td class="tdl"><span class="smcap">Unicellular Solitary Hairs</span></td>
-<td class="tdr"><a href="#plate7">70</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">8</span></td>
-<td class="tdl"><span class="smcap">Clustered Unicellular Hairs</span></td>
-<td class="tdr"><a href="#plate8">71</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> <span class="pad1">9</span></td>
-<td class="tdl"><span class="smcap">Multicellular Uniseriate Non-branched Hairs</span></td>
-<td class="tdr"><a href="#plate9">73</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;10</td>
-<td class="tdl"><span class="smcap">Multicellular Multiseriate Non-branched Hairs</span></td>
-<td class="tdr"><a href="#plate10">75</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;11</td>
-<td class="tdl"><span class="smcap">Multicellular Uniseriate Branched Hairs</span></td>
-<td class="tdr"><a href="#plate11">76</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;12</td>
-<td class="tdl"><span class="smcap">Non-glandular Multicellular Hairs</span></td>
-<td class="tdr"><a href="#plate12">78</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;13</td>
-<td class="tdl"><span class="smcap">Multicellular Multiseriate Branched Hairs</span></td>
-<td class="tdr"><a href="#plate13">79</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;14</td>
-<td class="tdl"><span class="smcap">Multicellular Multiseriate Branched Hairs</span></td>
-<td class="tdr"><a href="#plate14">81</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;15</td>
-<td class="tdl"><span class="smcap">Multicellular Multiseriate Branched Hairs</span></td>
-<td class="tdr"><a href="#plate15">82</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;16</td>
-<td class="tdl"><span class="smcap">Periderm of Cascara Sagrada</span> (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D.C.)</td>
-<td class="tdr"><a href="#plate16">84</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;17</td>
-<td class="tdl"><span class="smcap">Mandrake Rhizome and White Cinnamon</span></td>
-<td class="tdr"><a href="#plate17">86</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;18</td>
-<td class="tdl"><span class="smcap">Periderm of White Oak</span> (<i lang="la" xml:lang="la">Quercus alba</i>, L.)</td>
-<td class="tdr"><a href="#plate18">87</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;19</td>
-<td class="tdl"><span class="smcap">Crystal-bearing Fibres of Barks</span></td>
-<td class="tdr"><a href="#plate19">91</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;20</td>
-<td class="tdl"><span class="smcap">Crystal-bearing Fibres of Barks</span></td>
-<td class="tdr"><a href="#plate20">93</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;21</td>
-<td class="tdl"><span class="smcap">Crystal-bearing Fibres of Leaves</span></td>
-<td class="tdr"><a href="#plate21">94</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;22</td>
-<td class="tdl"><span class="smcap">Branched Bast Fibres</span></td>
-<td class="tdr"><a href="#plate22">95</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;23</td>
-<td class="tdl"><span class="smcap">Porous and Striated Bast Fibres</span></td>
-<td class="tdr"><a href="#plate23">97</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;24</td>
-<td class="tdl"><span class="smcap">Porous and Non-striated Bast Fibres</span></td>
-<td class="tdr"><a href="#plate24">98</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;25</td>
-<td class="tdl"><span class="smcap">Non-porous and Striated Bast Fibres</span></td>
-<td class="tdr"><a href="#plate25">99</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;26</td>
-<td class="tdl"><span class="smcap">Non-porous and Non-striated Bast Fibres</span></td>
-<td class="tdr"><a href="#plate26">101</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;27</td>
-<td class="tdl"><span class="smcap">Groups of Bast Fibres</span></td>
-<td class="tdr"><a href="#plate27">102</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;28</td>
-<td class="tdl"><span class="smcap">Wood Fibres</span></td>
-<td class="tdr"><a href="#plate28">105</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;29</td>
-<td class="tdl"><span class="smcap">Catnip Stem and Motherwort Stem</span></td>
-<td class="tdr"><a href="#plate29">107</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;30</td>
-<td class="tdl"><span class="smcap">Collenchyma Cells</span></td>
-<td class="tdr"><a href="#plate30">108</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;31</td>
-<td class="tdl"><span class="smcap">Branched Stone Cells</span></td>
-<td class="tdr"><a href="#plate31">110</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;32</td>
-<td class="tdl"><span class="smcap">Porous and Striated Stone Cells</span></td>
-<td class="tdr"><a href="#plate32">113</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;33</td>
-<td class="tdl"><span class="smcap">Porous and Non-striated Stone Cells</span></td>
-<td class="tdr"><a href="#plate33">114</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;34</td>
-<td class="tdl"><span class="smcap">Cinnamon, Ruella Root, Cascara and Cinnamon</span></td>
-<td class="tdr"><a href="#plate34">115</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;35</td>
-<td class="tdl"><span class="smcap">Cross-sections of Endodermal Cells of</span></td>
-<td class="tdr"><a href="#plate35">117</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;36</td>
-<td class="tdl"><span class="smcap">Longitudinal Sections of Endodermal Cells</span></td>
-<td class="tdr"><a href="#plate36">119</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;37</td>
-<td class="tdl"><span class="smcap">Hypodermal Cells</span></td>
-<td class="tdr"><a href="#plate37">120</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;38</td>
-<td class="tdl"><span class="smcap">Cross-section of Sarsaparilla Root</span> (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth)</td>
-<td class="tdr"><a href="#plate38">123</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;39</td>
-<td class="tdl"><span class="smcap">Root Hairs</span> (Fragments)</td>
-<td class="tdr"><a href="#plate39">124</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;40</td>
-<td class="tdl"><span class="smcap">Annular and Spiral Vessels</span></td>
-<td class="tdr"><a href="#plate40">129</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;41</td>
-<td class="tdl"><span class="smcap">Spiral Vessels</span></td>
-<td class="tdr"><a href="#plate41">130</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;42</td>
-<td class="tdl"><span class="smcap">Sclariform Vessels</span></td>
-<td class="tdr"><a href="#plate42">132</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;43</td>
-<td class="tdl"><span class="smcap">Reticulate Vessels</span></td>
-<td class="tdr"><a href="#plate43">133</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;44</td>
-<td class="tdl"><span class="smcap">Pitted Vessels</span></td>
-<td class="tdr"><a href="#plate44">134</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;45</td>
-<td class="tdl"><span class="smcap">Vessels</span></td>
-<td class="tdr"><a href="#plate45">135</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;46</td>
-<td class="tdl"><span class="smcap">Sieve Tube</span></td>
-<td class="tdr"><a href="#plate46">137</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;47</td>
-<td class="tdl"><span class="smcap">Radial Longitudinal Section of White Sandalwood</span> (<i lang="la" xml:lang="la">Santalum album</i>, L.)</td>
-<td class="tdr"><a href="#plate47">140</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;48</td>
-<td class="tdl"><span class="smcap">Kava-kava Root and White Pine Bark</span></td>
-<td class="tdr"><a href="#plate48">143</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;49</td>
-<td class="tdl"><span class="smcap">Black Indian Hemp and Black Indian Hemp Root</span></td>
-<td class="tdr"><a href="#plate49">145</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;50</td>
-<td class="tdl"><span class="smcap">Latex Vessels</span></td>
-<td class="tdr"><a href="#plate50">146</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;51</td>
-<td class="tdl"><span class="smcap">Parenchyma Cells</span></td>
-<td class="tdr"><a href="#plate51">148</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;52</td>
-<td class="tdl"><span class="smcap">Grindelia Stem (longitudinal) and Grindelia Stem (cross-section)</span></td>
-<td class="tdr"><a href="#plate52">149</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;53</td>
-<td class="tdl"><span class="smcap">Aconite Stem and Peppermint Stem</span></td>
-<td class="tdr"><a href="#plate53">152</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;54</td>
-<td class="tdl"><span class="smcap">Types of Stoma</span></td>
-<td class="tdr"><a href="#plate54">153</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;55</td>
-<td class="tdl"><span class="smcap">Leaf Epidermi With Stoma</span></td>
-<td class="tdr"><a href="#plate55">155</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;56</td>
-<td class="tdl"><span class="smcap">Belladonna Leaf, Deer Tongue Leaf and White Pine Leaf</span></td>
-<td class="tdr"><a href="#plate56">156</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;57</td>
-<td class="tdl"><span class="smcap">Elder Bark</span></td>
-<td class="tdr"><a href="#plate57">159</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;58</td>
-<td class="tdl"><span class="smcap">Intercellular Air Spaces</span></td>
-<td class="tdr"><a href="#plate58">160</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;59</td>
-<td class="tdl"><span class="smcap">Irregular Intercellular Air Spaces</span></td>
-<td class="tdr"><a href="#plate59">161</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;60</td>
-<td class="tdl"><span class="smcap">Glandular Hairs</span></td>
-<td class="tdr"><a href="#plate60">165</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;61</td>
-<td class="tdl"><span class="smcap">Stalked Glandular Hairs</span></td>
-<td class="tdr"><a href="#plate61">167</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;62</td>
-<td class="tdl"><span class="smcap">Calamus Rhizome and White Pine Bark</span></td>
-<td class="tdr"><a href="#plate62">169</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;63</td>
-<td class="tdl"><span class="smcap">Canella Alba Bark and Klip Buchu Leaf</span></td>
-<td class="tdr"><a href="#plate63">170</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;64</td>
-<td class="tdl"><span class="smcap">Bitter Orance Peel and White Pine Leaf</span></td>
-<td class="tdr"><a href="#plate64">171</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;65</td>
-<td class="tdl"><span class="smcap">Cinnamon, Calumba, Parenchyma, Sarsaparilla, Leptandra, Quebracho, Blackberry</span></td>
-<td class="tdr"><a href="#plate65">174</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;66</td>
-<td class="tdl"><span class="smcap">Mucilage and Resin</span></td>
-<td class="tdr"><a href="#plate66">175</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;67</td>
-<td class="tdl"><span class="smcap">Cross-section of Skunk-cabbage Leaf</span> (<i lang="la" xml:lang="la">Symplocarpus fœtidus</i>, [L.] Nutt.)</td>
-<td class="tdr"><a href="#plate67">177</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;68</td>
-<td class="tdl"><span class="smcap">Reserve Cellulose</span></td>
-<td class="tdr"><a href="#plate68">180</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;69</td>
-<td class="tdl"><span class="smcap">Reserve Cellulose</span></td>
-<td class="tdr"><a href="#plate69">181</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;70</td>
-<td class="tdl"><span class="smcap">Starch</span></td>
-<td class="tdr"><a href="#plate70">186</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;71</td>
-<td class="tdl"><span class="smcap">Starch</span></td>
-<td class="tdr"><a href="#plate71">187</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;72</td>
-<td class="tdl"><span class="smcap">Starch</span></td>
-<td class="tdr"><a href="#plate72">189</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;73</td>
-<td class="tdl"><span class="smcap">Starch</span></td>
-<td class="tdr"><a href="#plate73">190</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;74</td>
-<td class="tdl"><span class="smcap">Starch</span></td>
-<td class="tdr"><a href="#plate74">191</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;75</td>
-<td class="tdl"><span class="smcap">Starch Grains</span></td>
-<td class="tdr"><a href="#plate75">192</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;76</td>
-<td class="tdl"><span class="smcap">Starch Masses</span></td>
-<td class="tdr"><a href="#plate76">193</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;77</td>
-<td class="tdl"><span class="smcap">Inulin</span> (<i lang="la" xml:lang="la">Inula helenium</i>, L.)</td>
-<td class="tdr"><a href="#plate77">195</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;77<em>a</em></td>
-<td class="tdl"><span class="smcap">Aleurone Grains</span></td>
-<td class="tdr"><a href="#plate77a">199</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;78</td>
-<td class="tdl"><span class="smcap">Micro-crystals</span></td>
-<td class="tdr"><a href="#plate78">201</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;79</td>
-<td class="tdl"><span class="smcap">Raphides</span></td>
-<td class="tdr"><a href="#plate79">203</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;80</td>
-<td class="tdl"><span class="smcap">Rosette Crystals</span></td>
-<td class="tdr"><a href="#plate80">204</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;81</td>
-<td class="tdl"><span class="smcap">Inclosed Rosette Crystals</span></td>
-<td class="tdr"><a href="#plate81">206</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;82</td>
-<td class="tdl"><span class="smcap">Solitary Crystal</span></td>
-<td class="tdr"><a href="#plate82">207</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;83</td>
-<td class="tdl"><span class="smcap">Solitary Crystals</span></td>
-<td class="tdr"><a href="#plate83">208</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;84</td>
-<td class="tdl"><span class="smcap">Solitary Crystals</span></td>
-<td class="tdr"><a href="#plate84">209</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;85</td>
-<td class="tdl"><span class="smcap">Solitary Crystals</span></td>
-<td class="tdr"><a href="#plate85">211</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;86</td>
-<td class="tdl"><span class="smcap">Solitary Crystals</span></td>
-<td class="tdr"><a href="#plate86">212</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;87</td>
-<td class="tdl"><span class="smcap">Rosette Crystals and Solitary Crystals Occurring in</span></td>
-<td class="tdr"><a href="#plate87">213</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;88</td>
-<td class="tdl"><span class="smcap">Cystoliths</span></td>
-<td class="tdr"><a href="#plate88">214</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;89</td>
-<td class="tdl"><span class="smcap">Cross-section of Root of Spigelia Marylandica, L.</span></td>
-<td class="tdr"><a href="#plate89">220</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;90</td>
-<td class="tdl"><span class="smcap">Ruellia Root</span> (<i lang="la" xml:lang="la">Ruellia ciliosa</i>, Pursh.).</td>
-<td class="tdr"><a href="#plate90">222</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;91</td>
-<td class="tdl"><span class="smcap">Cross-section of Rhizome of Spigelia Marylandica, L.</span></td>
-<td class="tdr"><a href="#plate91">224</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;92</td>
-<td class="tdl"><span class="smcap">Cross-section of Rhizome of Ruellia Ciliosa, Pursh.</span></td>
-<td class="tdr"><a href="#plate92">225</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;93</td>
-<td class="tdl"><span class="smcap">Powdered Spigelia Marylandica, L.</span></td>
-<td class="tdr"><a href="#plate93">228</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;94</td>
-<td class="tdl"><span class="smcap">Powdered Ruellia Ciliosa</span>, Pursh.</td>
-<td class="tdr"><a href="#plate94">229</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;95</td>
-<td class="tdl"><span class="smcap">Cross-section of Stem of Spigelia Marylandica, L.</span></td>
-<td class="tdr"><a href="#plate95">234</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;96</td>
-<td class="tdl"><span class="smcap">Cross-section of Stem of Ruellia Ciliosa</span>, Pursh.</td>
-<td class="tdr"><a href="#plate96">236</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;97</td>
-<td class="tdl"><span class="smcap">Powdered Horehound</span> (<i lang="la" xml:lang="la">Marrubium vulgare</i>, L).</td>
-<td class="tdr"><a href="#plate97">238</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;98</td>
-<td class="tdl"><span class="smcap">Spurious Horehound</span> (<i lang="la" xml:lang="la">Marrubium peregrinum</i>, L.)</td>
-<td class="tdr"><a href="#plate98">239</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> &nbsp;&nbsp;99</td>
-<td class="tdl"><span class="smcap">Powdered Insect Flower Stems</span> (<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i>, [Trev.], Vis.)</td>
-<td class="tdr"><a href="#plate99">240</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 100</td>
-<td class="tdl"><span class="smcap">Cross-section of Buchu Stems</span> (<i lang="la" xml:lang="la">Barosma betulina</i> [Berg.], Barth, and Wendl.)</td>
-<td class="tdr"><a href="#plate100">243</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 101</td>
-<td class="tdl"><span class="smcap">Buchu Stem and Leptandra Rhizome</span></td>
-<td class="tdr"><a href="#plate101">244</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 102</td>
-<td class="tdl"><span class="smcap">Powdered Buchu Stems</span> (<i lang="la" xml:lang="la">Barosma betulina</i> [Berg.], Barth. and Wendl.).</td>
-<td class="tdr"><a href="#plate102">246</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 103</td>
-<td class="tdl"><span class="smcap">Cross-section of Unrossed White Pine Bark</span> (<i lang="la" xml:lang="la">Pinus strobus</i>, L.)</td>
-<td class="tdr"><a href="#plate103">249</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 104</td>
-<td class="tdl"><span class="smcap">Powdered White Pine Bark</span> (<i lang="la" xml:lang="la">Pinus strobus</i>, L.)</td>
-<td class="tdr"><a href="#plate104">251</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 105</td>
-<td class="tdl"><span class="smcap">Cross-section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)</td>
-<td class="tdr"><a href="#plate105">255</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 106</td>
-<td class="tdl"><span class="smcap">Tangential Section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)</td>
-<td class="tdr"><a href="#plate106">256</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 107</td>
-<td class="tdl"><span class="smcap">Radial Section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)</td>
-<td class="tdr"><a href="#plate107">257</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 108</td>
-<td class="tdl"><span class="smcap">Cross-section of Klip Buchu Just Over the Vein</span></td>
-<td class="tdr"><a href="#plate108">261</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 109</td>
-<td class="tdl"><span class="smcap">Powdered Klip Buchu</span></td>
-<td class="tdr"><a href="#plate109">263</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 110</td>
-<td class="tdl"><span class="smcap">Cross-section Mountain Laurel</span> (<i lang="la" xml:lang="la">Kalmia latifolia</i>, L.)</td>
-<td class="tdr"><a href="#plate110">265</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 111</td>
-<td class="tdl"><span class="smcap">Cross-section Trailing Arbutus Leaf</span> (<i lang="la" xml:lang="la">Epigæa repens</i>, L.)</td>
-<td class="tdr"><a href="#plate111">266</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 112</td>
-<td class="tdl"><span class="smcap">Powdered Insect Flower Leaves</span></td>
-<td class="tdr"><a href="#plate112">268</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 113</td>
-<td class="tdl"><span class="smcap">Smooth-walled Pollen Grains</span></td>
-<td class="tdr"><a href="#plate113">271</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 114</td>
-<td class="tdl"><span class="smcap">Spiny Walled Pollen Grains</span></td>
-<td class="tdr"><a href="#plate114">272</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 115</td>
-<td class="tdl"><span class="smcap">Papillæ</span></td>
-<td class="tdr"><a href="#plate115">275</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 116</td>
-<td class="tdl"><span class="smcap">Papillæ of Stigmas</span></td>
-<td class="tdr"><a href="#plate116">276</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 117</td>
-<td class="tdl"><span class="smcap">Papillæ of Stigmas</span></td>
-<td class="tdr"><a href="#plate117">277</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 118</td>
-<td class="tdl"><span class="smcap">Powdered Closed Insect Flower</span></td>
-<td class="tdr"><a href="#plate118">279</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 119</td>
-<td class="tdl"><span class="smcap">Powdered Open Insect Flower</span></td>
-<td class="tdr"><a href="#plate119">281</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 120</td>
-<td class="tdl"><span class="smcap">Powdered White Daisies</span> (<i lang="la" xml:lang="la">Chrysanthemum leucanthemum</i>, L.)</td>
-<td class="tdr"><a href="#plate120">283</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 121</td>
-<td class="tdl"><span class="smcap">Cross-section of Celery Fruit</span> (<i lang="la" xml:lang="la">Apium graveolens</i>, L.)</td>
-<td class="tdr"><a href="#plate121">286</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 121</td>
-<td class="tdl"><span class="smcap">Cross-section of Celery Fruit</span> (<i lang="la" xml:lang="la">Apium graveolens</i>, L.)</td>
-<td class="tdr"><a href="#plate122">286</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 123</td>
-<td class="tdl"><span class="smcap">Cross-section Sweet Almond Seed</span></td>
-<td class="tdr"><a href="#plate123">290</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 124</td>
-<td class="tdl"><span class="smcap">Cross-section of a Radial Vascular Bundle of Skunk Cabbage Root</span></td>
-<td class="tdr"><a href="#plate124">293</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 125</td>
-<td class="tdl"><span class="smcap">Cross-section of a Phloem-centric Bundle of Calamus Rhizome</span> (<i lang="la" xml:lang="la">Acorus calamus</i>, L.)</td>
-<td class="tdr"><a href="#plate125">294</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 126</td>
-<td class="tdl"><span class="smcap">Cross-section of a Closed Collateral Bundle of Mandrake Stem</span> (<i lang="la" xml:lang="la">Podophyllum peltatum</i>, L.)</td>
-<td class="tdr"><a href="#plate126">286</a></td>
-</tr>
-<tr>
-<td class="tdl"><span class="smcap">Plate</span> 127</td>
-<td class="tdl"><span class="smcap">Bi-collateral Bundle of Pumpkin Stem</span> (<i lang="la" xml:lang="la">Curcurbita pepo</i>, L.)</td>
-<td class="tdr"><a href="#plate127">297</a></td>
-</tr>
-</table>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<h2 class="nobreak p10 pb10" id="Part_I">Part I<br />
-<span class="fs80">SIMPLE AND COMPOUND MICROSCOPES<br />
-AND MICROSCOPIC TECHNIC</span></h2>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_3">[3]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_I">CHAPTER I<br />
-<span class="fs80">THE SIMPLE MICROSCOPES</span></h3>
-</div>
-
-<p>The construction and use of the <span class="bold">simple microscope</span> (magnifiers)
-undoubtedly date back to very early times. There is
-sufficient evidence to prove that spheres of glass were used as
-burning spheres and as magnifiers by people antedating the
-Greeks and Romans.</p>
-
-<p>The simple microscopes of to-day have a very wide range of
-application and a corresponding variation in structure and in
-appearance.</p>
-
-<p>Simple microscopes are used daily in classifying and studying
-crude drugs, testing linen and other cloth, repairing watches,
-in reading, and identifying insects. The more complex simple
-microscopes are used in the dissection and classification of
-flowers.</p>
-
-<p>The <span class="bold">watchmaker’s loupe</span>, the <span class="bold">linen tester</span>, the <span class="bold">reading glass</span>,
-the <span class="bold">engraver’s lens</span>, and the simplest folding magnifiers consist
-of a double convex lens. Such a lens produces an erect, enlarged
-image of the object viewed when the lens is placed so
-that the object is within its focal distance. The focal distance
-of a lens varies according to the curvature of the lens. The
-greater the curvature, the shorter the focal distance and the
-greater the magnification.</p>
-
-<p>The more complicated simple microscope consists of two or
-more lenses. The double and triple magnifiers consist of two
-and three lenses respectively.</p>
-
-<p>When an object is viewed through three lenses, the magnification
-is greater than when viewed through one or two lenses,
-but a smaller part of the object is magnified.</p>
-
-<p><span class="pagenum" id="Page_4">[4]</span></p>
-
-<h4>FORMS OF SIMPLE MICROSCOPES</h4>
-
-<h5>TRIPOD MAGNIFIER</h5>
-
-<p>The <span class="bold">tripod magnifier</span> (Fig. 1) is a simple lens mounted on a
-mechanical stand. The tripod is placed over the object and
-the focus is obtained by means of a screw which raises or lowers
-the lens, according to the degree it is magnified.</p>
-
-<h5>WATCHMAKER’S LOUPE</h5>
-
-<p>The <span class="bold">watchmaker’s loupe</span> (Fig. 2) is a one-lens magnifier
-mounted on an ebony or metallic tapering rim, which can be
-placed over the eye and held in position by frowning or contracting
-the eyelid.</p>
-
-<div class="figcenter illowp100" id="fig1-fig2" style="max-width: 30em;">
-  <img class="w100 p1" src="images/fig1-fig2.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 1.&mdash;Tripod Magnifier <span class="smcap pad6">Fig.</span> 2.&mdash;Watchmaker’s Loupe</div>
-</div>
-
-<h5>FOLDING MAGNIFIER</h5>
-
-<p>The <span class="bold">folding magnifier</span> (Fig. 3) of one or more lenses is mounted
-in such a way that, when not in use, the lenses fold up like the
-blade of a knife, and when so folded are effectively protected
-from abrasion by the upper and lower surfaces of the folder.</p>
-
-<div class="figcenter illowp100" id="fig3-fig4" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig3-fig4.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 3.&mdash;Folding Magnifier <span class="smcap pad8">Fig.</span> 4.&mdash;Reading Glass</div>
-</div>
-
-<h5>READING GLASSES</h5>
-
-<p><span class="bold">Reading glasses</span> (Fig. 4) are large simple magnifiers, often
-six inches in diameter. The lens is encircled with a metal band
-and provided with a handle.</p>
-
-<p><span class="pagenum" id="Page_5">[5]</span></p>
-
-<div class="figcenter illowp100" id="fig5" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig5.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 5.&mdash;Steinheil Aplanatic Lens</div>
-</div>
-
-<h5>STEINHEIL APLANATIC LENSES</h5>
-
-<p><span class="bold">Steinheil aplanatic lenses</span> (Fig. 5) consist of three or four
-lenses cemented together. The combination is such that the
-field is large, flat, and achromatic. These lenses are suitable
-for field, dissecting, and pocket use. When such lenses are
-placed in simple holders, they make good dissecting microscopes.</p>
-
-<div class="figcenter illowp61" id="fig6" style="max-width: 25.6875em;">
-  <img class="w100 p1" src="images/fig6.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 6.&mdash;Dissecting microscope</div>
-</div>
-
-<h5>DISSECTING MICROSCOPE</h5>
-
-<p>The <span class="bold">dissecting microscope</span> (Fig. 6) consists of a Steinheil
-lens and an elaborate stand, a firm base, a pillar, a rack and<span class="pagenum" id="Page_6">[6]</span>
-pinion, a glass stage, beneath which there is a groove for holding
-a metal plate with one black and one white surface. The
-nature of the object under observation determines whether a
-plate is used. When the plate is used and when the object is
-studied by reflected light it is sometimes desirable to use the
-black and sometimes the white surface. The mirror, which has
-a concave and a plain surface, is used to reflect the light on the
-glass stage when the object is studied by transmitted light.
-The dissecting microscope magnifies objects up to twenty
-diameters, or twenty times their real size.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_7">[7]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_II">CHAPTER II<br />
-<span class="fs80">COMPOUND MICROSCOPES</span></h3>
-</div>
-
-<p>The <span class="bold">compound microscope</span> has undergone wonderful changes
-since 1667, the days of Robert Hooke. When we consider the
-crude construction and the limitations of Robert Hooke’s microscope,
-we marvel at the structural perfection and the unlimited
-possibilities of the modern instrument. The advancement made
-in most sciences has followed the gradual perfection of this
-instrument.</p>
-
-<p>The illustration of Robert Hooke’s microscope (Fig. 7) will
-convey to the mind more eloquently than words the crudeness
-of the early microscopes, especially when it is compared with
-the present-day microscopes.</p>
-
-<h4 id="STRUCTURE_OF_THE_COMPOUND_MICROSCOPE">STRUCTURE OF THE COMPOUND MICROSCOPE</h4>
-
-<p>The parts of the compound microscope (Fig. 8) may be
-grouped into&mdash;first, the mechanical, and, secondly, into the
-optical parts.</p>
-
-<h5 id="THE_MECHANICAL_PARTS">THE MECHANICAL PARTS</h5>
-
-<p>1. The <span class="bold">foot</span> is the basal part, the part which supports all
-the other mechanical and optical parts. The foot should be
-heavy enough to balance the other parts when they are inclined.
-Most modern instruments have a three-parted or tripod-shaped
-base.</p>
-
-<p>2. The <span class="bold">pillar</span> is the vertical part of the microscope attached
-to the base. The pillar is joined to the limb by a hinged joint.
-The hinges make it possible to incline the microscope at any
-angle, thus lowering its height. In this way, short, medium,
-and tall persons can use the microscope with facility. The
-part of the pillar above the hinge is called the <em>limb</em>. The limb
-may be either straight or curved. The curved form is preferable,
-since it offers a more suitable surface to grasp in transferring
-from box or shelf to the desk, and <em>vice versa</em>.</p>
-
-<p><span class="pagenum" id="Page_8">[8]</span></p>
-
-<div class="figcenter illowp77" id="fig7" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig7.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 7.&mdash;Compound Microscope of Robert Hooke</div>
-</div>
-
-<p><span class="pagenum" id="Page_9">[9]</span></p>
-
-<p>3. The <span class="bold">stage</span> is either stationary or movable, round or
-square, and is attached to the limb just above the hinge. The
-upper surface is made of a composition which is not easily
-attacked by moisture and reagents. The centre of the stage is
-perforated by a circular opening.</p>
-
-<p>4. The <span class="bold">sub-stage</span> is attached below the stage and is for the
-purpose of holding the iris diaphragm and Abbé condenser.
-The raising and lowering of the sub-stage are accomplished by
-a rack and pinion.</p>
-
-<p>5. The <span class="bold">iris diaphragm</span>, which is held in the sub-stage below
-the Abbé condenser, consists of a series of metal plates, so arranged
-that the light entering the microscope may be cut off
-completely or its amount regulated by moving a control pin.</p>
-
-<p>6. The <span class="bold">fine adjustment</span> is located either at the side or at
-the top of the limb. It consists of a fine rack and pinion, and
-is used in focusing an object when the low-power objective is in
-position, or in finding and focusing the object when the high-power
-objective is in position.</p>
-
-<p>7. The <span class="bold">coarse adjustment</span> is a rack and pinion used in raising
-and lowering the body-tube and in finding the approximate
-focus when either the high- or low-power objective is in position.</p>
-
-<p>8. The <span class="bold">body-tube</span> is the path traveled by the rays of light
-entering the objectives and leaving by the eye-piece. To the
-lower part of the tube is attached the nose-piece, and resting
-in its upper part is the draw-tube, which holds the eye-piece.
-On the outer surface of the draw-tube there is a scale which
-indicates the distance it is drawn from the body-tube.</p>
-
-<p>9. The <span class="bold">nose-piece</span> may be simple, double, or triple, and it
-is protected from dust by a circular piece of metal. Double and
-triple nose-pieces may be revolved, and like the simple nose-piece
-they hold the objectives in position.</p>
-
-<h5 id="THE_OPTICAL_PARTS">THE OPTICAL PARTS</h5>
-
-<p>1. The <span class="bold">mirror</span> is a sub-stage attachment one surface of which
-is plain and the other concave. The plain surface is used with
-an Abbé condenser when the source of light is distant, while
-the concave surface is used with instruments without an Abbé
-condenser when the source of light is near at hand.</p>
-
-<p><span class="pagenum" id="Page_10">[10]</span></p>
-
-<div class="figcenter illowp46" id="fig8" style="max-width: 23.4375em;">
-  <img class="w100 p1" src="images/fig8.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 8.&mdash;Compound Microscope</div>
-</div>
-
-<p><span class="pagenum" id="Page_11">[11]</span></p>
-
-<p>2. The <span class="bold">Abbé condenser</span> (Fig. 9) is a combination of two or
-more lenses, arranged so as to concentrate the light on the
-specimen placed on the stage. The condenser is located in the
-opening of the stage, and its uppermost
-surface is circular and flat.</p>
-
-<div class="figcenter illowp73" id="fig9" style="max-width: 15.3125em;">
-  <img class="w100 p1" src="images/fig9.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 9&mdash;Abbé Condenser</div>
-</div>
-
-<p>3. <span class="bold">Objectives</span> (Figs. 10, 11, and 12).
-There are low, medium, and high-power
-objectives. The low-power objectives have
-fewer and larger lenses, and they magnify
-least, but they show more of the object than
-do the high-power objectives.
-There are three chief types of objectives:
-First, dry objectives; second, wet
-objectives, of which there are the water-immersion objectives;
-and third, the oil-immersion objectives. The dry
-objectives are used for most histological and pharmacognostical
-work. For studying smaller objects the water objective
-is sometimes desirable, but in bacteriological work the
-oil-immersion objective is almost exclusively used. The globule
-of water or oil, as the case may be, increases the amount of light
-entering the objective, because the oil and water bend many
-rays into the objective which would otherwise escape.</p>
-
-<div class="figcenter illowp100" id="fig10-fig11-fig12" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig10-fig11-fig12.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 10. <span class="smcap pad10">Fig.</span> 11. <span class="smcap pad10">Fig.</span> 12.<br />Objectives.</div>
-</div>
-
-<p>4. <span class="bold">Eye-pieces</span> (Figs. 13, 14, and 15) are of variable length,
-but structurally they are somewhat similar. The eye-piece
-consists of a metal tube with a blackened inner tube. In the<span class="pagenum" id="Page_12">[12]</span>
-centre of this tube there is a small diaphragm for holding the
-ocular micrometer. In the lower end of the tube a lens is fastened
-by means of a screw. This, the field lens, is the larger
-lens of the ocular. The upper, smaller lens is fastened in the
-tube by a screw, but there is a projecting collar which rests,
-when in position, on the draw-tube.</p>
-
-<div class="figcenter illowp100" id="fig13-fig14-fig15" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig13-fig14-fig15.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig.</span> 13. <span class="smcap pad12">Fig.</span> 14 <span class="smcap pad10">Fig.</span> 15<br />Eye-Pieces.</div>
-</div>
-
-<p>The longer the tube the lower the magnification. For
-instance, a two-inch ocular magnifies less than an inch and a
-half, a one-inch less than a three-fourths of an inch, etc.</p>
-
-<p>The greater the curvature of the
-lenses of the ocular the higher will be
-the magnification and the shorter the
-tube-length.</p>
-
-
-<h4 id="FORMS_OF_COMPOUND_MICROSCOPES">FORMS OF COMPOUND MICROSCOPES</h4>
-
-<p>The following descriptions refer to
-three different models of compound
-microscopes: one which is used chiefly
-as a pharmacognostic microscope, one
-as a research microscope stand, while
-the third type represents a research
-microscope stand of highest order,
-which is used at the same time for
-taking microphotographs.</p>
-
-
-<div class="figcenter illowp40" id="fig16" style="max-width: 20.125em;">
-  <img class="w100 p1" src="images/fig16.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 16.</span>&mdash;Pharmacognostic
-Microscope</div>
-</div>
-
-<h5>PHARMACOGNOSTIC MICROSCOPE</h5>
-
-<p>The <span class="bold">pharmacognostic microscope</span>
-(Fig. 16) is an instrument which<span class="pagenum" id="Page_13">[13]</span>
-embodies only those parts which are most essential for the
-examination of powdered drugs, bacteria, and urinary
-sediments. This microscope is provided with a stage of the
-dimensions 105 × 105 mm. This factor and the distance of
-80 mm. from the optical centre to the handle arm render it
-available for the examination of even very large objects and
-preparations, or preparations suspended in glass dishes. The
-stand is furnished with a side micrometer, a fine adjustment
-having knobs on both sides, thereby permitting the manipulation
-of the micrometer screw either by left or right hand. The
-illuminating apparatus consists of the Abbé condenser of numerical
-aperture of 1.20, to which is attached an iris diaphragm for
-the proper adjustment of the light. A worm screw, mounted
-in connection with the condenser, serves for the raising and
-lowering of the condenser, so that the cone of illuminating
-pencils can be arranged in accordance to the objective employed
-and to the preparation under observation. The objectives
-necessary are those of the achromatic type, possessing a focal
-length of 16.2 mm. and 3 mm. Oculars which render the best
-results in regard to magnification in connection with the two
-objectives mentioned are the Huyghenian eye-pieces II and IV
-so that magnifications are obtained varying from 62 to 625.
-It is advisable, however, to have the microscope equipped with
-a triple revolving nose-piece for the objectives, so that provision
-is made for the addition of an oil-immersion objective at any
-time later should the microscope become available for bacteriological
-investigations.</p>
-
-<h5>THE RESEARCH MICROSCOPE</h5>
-
-<p>The <span class="bold">research microscope</span> used in research work (Fig. 17) must
-be equipped more elaborately than the microscope especially
-designed for the use of the pharmacognosist. While the simple
-form of microscope is supplied with the small type of Abbé
-condenser, the research microscope is furnished with a large
-illuminating apparatus of which the iris diaphragm is mounted
-on a rack and pinion, allowing displacement obliquely to the
-optical centre, also to increase resolving power in the objectives
-when observing those objects which cannot be revealed to the
-best advantage with central illumination. Another iris is<span class="pagenum" id="Page_14">[14]</span>
-furnished above the condenser; this iris becomes available the
-instant an object is to be observed without the aid of the condenser,
-in which case the upper iris diaphragm allows proper
-adjustment of the light. The mirror, one side plane, the other
-concave, is mounted on a movable bar, along which it can
-be slid&mdash;another convenience for the adjustment of the light.
-The microscope stage of this stand is of the round, rotating
-and centring pattern, which permits a limited motion to the
-object slide: The rotation of the microscope stage furnishes
-another convenience in the examination of objects in polarized
-light, allowing the preparation to be rotated in order to
-distinguish the polarization properties of the objects under
-observation.</p>
-
-<div class="figcenter illowp79" id="fig17-fig18" style="max-width: 46.875em;">
-  <img class="w100 p1" src="images/fig17-fig18.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 17.</span>&mdash;Research
-Microscope <span class="smcap pad10">Fig. 18.</span>&mdash;Special Research Microscope</div>
-</div>
-
-<h5>SPECIAL RESEARCH MICROSCOPE</h5>
-
-<p>A <span class="bold">special research microscope</span> of the highest order (Fig. 18)
-is supplied with an extra large body tube, which renders it of<span class="pagenum" id="Page_15">[15]</span>
-special advantage for micro-photography. Otherwise in its
-mechanical equipment it resembles very closely the medium-sized
-research microscope stand, with the exception that the
-stand is larger in its design, therefore offering universal application.
-In regard to the illuminating apparatus, it is advisable
-to mention that the one in the large research microscope stand
-is furnished with a three-lens condenser of a numerical aperture
-of 1.40, while the medium-sized research stand is provided with
-a two-lens condenser of a numerical aperture of 1.20. The
-stage of the microscope is provided with a cross motion&mdash;the
-backward and forward motion of the preparation is secured by
-rack and pinion, while the side motion
-is controlled by a micrometric worm
-screw. In cases where large preparations
-are to be photographed, the
-draw-tube with ocular and the slider
-in which the draw-tubes glide are
-removed to allow the full aperture
-of wide-angle objectives to be made
-use of.</p>
-
-<div class="figcenter illowp36" id="fig19" style="max-width: 18.1875em;">
-  <img class="w100 p1" src="images/fig19.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 19.</span>&mdash;Greenough
-Binocular Microscope</div>
-</div>
-
-<h5>BINOCULAR MICROSCOPE</h5>
-
-<p>The <span class="bold">Greenough binocular microscope</span>,
-as shown in Fig. 19, consists
-of a microscope stage with two tubes
-mounted side by side and moving on
-the same rack and pinion for the
-focusing adjustment. Either tube
-can be used without the other. The
-oculars are capable of more or less
-separation to suit the eyes of different
-observers. In each of the drub-like
-mountings, near the point where the
-oculars are introduced, porro-prisms
-have been placed, which erect the image. This microscope
-gives most perfect stereoscopic images, which are erect instead
-of inverted, as in the monocular compound microscopes. The
-Greenough binocular microscope is especially adapted for dissection
-and for studying objects of considerable thickness.</p>
-
-<p><span class="pagenum" id="Page_16">[16]</span></p>
-
-<h5>POLARIZATION MICROSCOPE</h5>
-
-<p>The <span class="bold">polarization microscope</span> (Fig. 20) is used chiefly for the
-examination of crystals and mineral sections as well as for the
-observation of organic bodies in polarized light. It can, however,
-also be used for the examination of regular biological
-preparations.</p>
-
-<div class="figcenter illowp46" id="fig20" style="max-width: 19.25em;">
-  <img class="w100 p1" src="images/fig20.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 20.</span>&mdash;Polarization Microscope</div>
-</div>
-
-<p>If compared with the regular biological microscope, the
-polarization microscope is found characteristic of the following
-points: it is supplied with a polarization arrangement. The
-latter consists of a polarizer and analyzer. The polarizer is
-situated in a rotating mount beneath the condensing system.
-The microscope, of which the diagram is
-shown, possesses a triple “Ahrens” prism
-of calcite. The entering light is divided
-into two polarized parts, situated perpendicularly
-to each other. The so-called
-“ordinary” rays are reflected to one side
-by total reflection, which takes place on
-the inner cemented surface of the triple
-prism, allowing the so-called “extraordinary”
-rays to pass through the condenser.
-If the prism is adjusted to its
-focal point, it is so situated that the
-vibration plane of the extra-ordinary rays
-are in the same position as shown in
-the diagram of the illustration.</p>
-
-<p>The analyzer is mounted within the
-microscope-tube above the objective.
-Situated on a sliding plate, it can be shifted into the optical
-axis whenever necessary. The analyzer consists of a polarization
-prism after Glan-Thompson. The polarization plane
-of the active extraordinary rays is situated perpendicularly
-to the plane as shown in the diagram. The polarization
-prisms are ordinarily crossed. In this position the field of
-the microscope is darkened as long as no substance of a double
-refractive index has been introduced between the analyzer and
-polarizer. In rotating the polarizer up to the mark 90, the
-polarization prisms are mounted parallel and the field of the<span class="pagenum" id="Page_17">[17]</span>
-microscope is lighted again. Immediately above the analyzer
-and attached to the mounting of the analyzer a lens of a comparatively
-long focal length has been placed in order to overcome
-the difference in focus created by the introduction of the
-analyzer into the optical rays.</p>
-
-<p>The condensing system is mounted on a slider, and, furthermore,
-can be raised and lowered along the optical centre by
-means of a rack-and-pinion adjustment. If lowered sufficiently,
-the condensing system can be thrown to the side to be removed
-from the optical rays. The condenser consists of three lenses.
-The two upper lenses are separately mounted to an arm, which
-permits them to be tilted to one side in order to be removed
-from the optical rays. The complete condenser is used only
-in connection with high-power objectives. As far as low-power
-objectives are concerned, the lower condensing lens alone is
-made use of, and the latter is found mounted to the polarizer
-sleeve. Below the polarizer and above the lower condensing
-lens an iris diaphragm is found.</p>
-
-<p>The microscope table is graduated on its periphery, and,
-furthermore, carries a vernier for more exact reading.</p>
-
-<p>The polarization microscope is not furnished with an objective
-nose-piece. Every objective, however, is supplied with
-an individual centring head, which permits the objective to be
-attached to an objective clutch-changer, situated at the lower end
-of the microscope-tube. The centring head permits the objectives
-to be perfectly centred and to remain centred even if another
-objective is introduced into the objective clutch-changer.</p>
-
-<p>At an angle of 45 degrees to the polarization plane of polarizer
-and analyzer, a slot has been provided, which serves for the
-introduction of compensators.</p>
-
-<p>Between analyzer and ocular, another slot is found which
-permits the Amici-Bertrand lens to be introduced into the
-optical axis. The slider for the Bertrand lens is supplied with
-two centring screws whereby this lens can be perfectly and
-easily centred. The Bertrand lens serves the purpose of
-observing the back focal plane of the microscope objective. In
-order to allow the Bertrand lens to be focused, the tube can be
-raised and lowered for this purpose. An iris diaphragm is
-mounted above the Bertrand lens.</p>
-
-<p><span class="pagenum" id="Page_18">[18]</span></p>
-
-<p>If the Bertrand lens is shifted out of the optical axis, one can
-observe the preparation placed upon the microscope stage and,
-depending on its thickness or its double refraction, the interference
-color of the specimen. This interference figure is called
-the orthoscopic image and, accordingly, one speaks of the microscope
-as being used as an “orthoscope.”</p>
-
-<p>After the Bertrand lens has been introduced into the optical
-axis, the interference figure is visible in the back focal plane of
-the objective. Each point of this interference figure corresponds
-to a certain direction of the rays of the preparation itself. This
-arrangement permits observation of the change of the reflection
-of light taking place in the preparation, this in accordance with
-the change of the direction of the rays. This interference figure
-is called the conoscopic image, and, accordingly, the microscope
-is used as a “conoscope.”</p>
-
-<p>Many types of polarization microscopes have been constructed;
-those of a more elaborate form are used for research
-investigations; others of smaller design for routine investigations.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_19">[19]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_III">CHAPTER III<br />
-<span class="fs80">MICROSCOPIC MEASUREMENTS</span></h3>
-</div>
-
-<p>In making critical examinations of powdered drugs, it is
-frequently necessary to measure the elements under observation,
-particularly in the case of starches and crystals.</p>
-
-<h4 id="OCULAR_MICROMETER">OCULAR MICROMETER</h4>
-
-<p>Microscopic measurements are made by the <span class="bold">ocular micrometer</span>
-(Fig. 21). This consists of a circular piece of transparent
-glass on the centre of which is etched a one- or two-millimeter
-scale divided into one hundred or two hundred divisions respectively.
-The value of each line is determined by standardizing
-with a stage micrometer.</p>
-
-<div class="figcenter illowp100" id="fig21_22" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig21_22.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 21.</span>&mdash;Ocular Micrometer  <span class="smcap pad6">Fig. 22.</span>&mdash;Stage Micrometer</div>
-</div>
-
-<h4 id="STAGE_MICROMETER">STAGE MICROMETER</h4>
-
-<p>The <span class="bold">stage micrometer</span> (Fig. 22) consists of a glass slide upon
-which is etched a millimeter scale divided into one hundred
-equal parts or lines: each line has a value of one hundredth of
-a millimeter.</p>
-
-<h5>STANDARDIZATION OF OCULAR MICROMETER <br />WITH LOW-POWER OBJECTIVE</h5>
-
-<p>Having placed the ocular micrometer in the eye-piece and
-the stage micrometer on the centre of the stage, focus until<span class="pagenum" id="Page_20">[20]</span>
-the lines of the stage micrometer are clearly seen. Then adjust
-the scales until the lines of the stage micrometer are parallel
-with and directly under the lines of the ocular micrometer.</p>
-
-<p>Ascertain the number of lines of the stage micrometer covered
-by the one hundred lines of the ocular micrometer. Then
-calculate the value of each line of the ocular. This is done in
-the following manner:</p>
-
-<p>If the one hundred lines of the ocular cover seventy-five
-lines of the stage micrometer, then the one hundred lines of
-the ocular micrometer are equivalent to seventy-five one-hundredths,
-or three-fourths, of a millimeter. One line of the
-ocular micrometer will therefore be equivalent to one-hundredth
-of seventy-five one-hundredths, or .0075 part of a millimeter,
-and as a micron is the unit for measuring microscopic objects,
-this being equivalent to one one-thousandth of a millimeter,
-the value of each line of the ocular will therefore be 7.5 microns.</p>
-
-<div class="figcenter illowp80" id="fig23" style="max-width: 21.875em;">
-  <img class="w100 p1" src="images/fig23.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 23.</span>&mdash;Micrometer Eye-Piece</div>
-</div>
-
-<p>With the high-power objective in place, ascertain the value
-of each line of the ocular. If one hundred lines of the ocular
-cover only twelve lines of the stage micrometer, then the one
-hundred lines of the ocular are equivalent to twelve one-hundredths
-of a millimeter, the value of one line being equivalent
-to one one-hundredth of twelve one-hundredths, or twelve ten-thousandths
-of a millimeter, or .0012, or 1.2 <em>µ</em>.</p>
-
-<p>It will therefore be seen that objects as small as a thousandth
-of a millimeter can be accurately measured by the ocular
-micrometer.</p>
-
-<p>In making microscopic measurements it is only necessary<span class="pagenum" id="Page_21">[21]</span>
-to find how many lines of the ocular scale are covered by the
-object. The number of lines multiplied by the equivalent of
-each line will be the size of the object in microns, or <em>micromillimeters</em>.</p>
-
-<div class="figcenter illowp73" id="fig24" style="max-width: 24.625em;">
-  <img class="w100 p1" src="images/fig24.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 24.</span>&mdash;Micrometer Eye-Piece</div>
-</div>
-
-<h4 id="MICROMETER_EYE-PIECES">MICROMETER EYE-PIECES</h4>
-
-<p><span class="bold">Micrometer eye-pieces</span> (Figs. 23 and 24) may be used in
-making measurements. These eye-pieces with micrometer combinations
-are preferred by some workers, but the ocular micrometer
-will meet the needs of the average worker.</p>
-
-
-<h4 id="MECHANICAL_STAGES">MECHANICAL STAGES</h4>
-
-<p>Moving objects by hand is tiresome and unsatisfactory, first,
-because of the possibility of losing sight of the object under
-observation, and secondly, because the field cannot be covered
-so systematically as when a mechanical stage is used for moving
-slides.</p>
-
-<p>The <span class="bold">mechanical stage</span> (Fig. 25) is fastened to the stage by
-a screw. The slide is held by two clamps. There is a rack and<span class="pagenum" id="Page_22">[22]</span>
-pinion for moving the slide to left or right, and another rack and
-pinion for moving the slide forward and backward.</p>
-
-<div class="figcenter illowp100" id="fig25-fig26" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig25-fig26.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 25.</span> Mechanical Stage <span class="smcap pad6">Fig. 26.</span>&mdash;Camera Lucida</div>
-</div>
-
-<h4 id="CAMERA_LUCIDA">CAMERA LUCIDA</h4>
-
-<p>The <span class="bold">camera lucida</span> is an optical mechanical device for aiding
-the worker in making drawings of microscopic objects. The
-instrument is particularly necessary in research work where it
-is desirable to reproduce an object in all its details. In fact, all
-reproductions illustrating original work should be made by
-means of the camera lucida or by microphotography.</p>
-
-<div class="figcenter illowp100" id="fig25_27-b" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig25_27-b.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 27.</span>&mdash;Camera Lucida</div>
-</div>
-
-<p>A great many different types of camera lucidas or <a id="DRAWING_APPARATUS">drawing apparatus</a>
-are obtainable, varying from simple-inexpensive to
-complex-expensive forms. Figs. 26, 27, and 28 show simple
-and complex forms.</p>
-
-<p><span class="pagenum" id="Page_23">[23]</span></p>
-
-<div class="figcenter illowp100" id="fig28" style="max-width: 40.625em;">
-  <img class="w100 p1" src="images/fig28.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 28.</span>&mdash;Drawing Apparatus</div>
-</div>
-
-<p><span class="pagenum" id="Page_24">[24]</span></p>
-
-<h4 id="MICROPHOTOGRAPHIC_APPARATUS">MICROPHOTOGRAPHIC APPARATUS</h4>
-
-<p>The <span class="bold">microphotographic apparatus</span> (Fig. 29), as the name
-implies, is an apparatus constructed in such a manner that it
-may be attached to a microscope when we desire to photograph
-microscopic objects. It consists of a metal base and a polished
-metal pillar for holding the bellows, slide holder, ground-glass
-observation plate, and eye-piece. In making photographs, the
-small end of the bellows is attached to the ocular of the microscope,
-the focus adjusted, and the object or objects photographed.
-More uniform results are obtained in making such
-photographs if an artificial light of an unvarying candle-power
-is used.</p>
-
-<div class="figcenter illowp100" id="fig29" style="max-width: 40.625em;">
-  <img class="w100 p1" src="images/fig29.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 29.</span>&mdash;Microphotographic Apparatus</div>
-</div>
-
-<p>There are obtainable more elaborate microphotographic
-apparatus than the one figured and described, but for most
-workers this one will prove highly satisfactory. It is possible,
-by inclining the tube of the microscope, to make good microphotographs
-with an ordinary plate camera. This is accomplished
-by removing the lens of the camera and attaching the
-bellows to the ocular, focusing, and photographing.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_25">[25]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_IV">CHAPTER IV<br />
-<span class="fs80">HOW TO USE THE MICROSCOPE</span></h3>
-</div>
-
-<p>In beginning work with the compound microscope, place
-the base of the microscope opposite your right shoulder, if you
-are right-handed; or opposite your left shoulder, if you are left-handed.
-Incline the body so that the ocular is on a level with
-your eye, if necessary; but if not, work with the body of the
-microscope in an erect position. In viewing the specimen, keep
-both eyes open. Use one eye for observation and the other
-for sketching. In this way it will not be necessary to remove
-the observation eye from the ocular unless it be to complete
-the details of a sketch.</p>
-
-
-<p><span class="bold">Learn to use both eyes.</span> Most workers, however, accustom
-themselves to using one eye; when they are sketching, they use
-both eyes, although it is not necessary to do so.</p>
-
-
-<p><span class="bold">Open the iris diaphragm</span>, and incline the mirror so that
-white light is reflected on the Abbé condenser. Place the slide
-on the centre of the stage, and if the slide contains a section
-of a plant, move the slide so as to place this specimen over the
-centre of the Abbé condenser. Then lower the body by means
-of the coarse adjustment until the low-power object, which
-should always be in position when work is begun, is within one-fourth
-of an inch of the stage. Then raise the body by means
-of the coarse adjustment until the object, or objects, in case a
-powder is being examined, is seen. Open and close the iris
-diaphragm, finally adjusting the opening so that the best possible
-illumination is obtained for bringing out clearly the structure
-of the object or objects viewed. Then regulate the focus
-by moving the body up or down by turning the fine adjustment.
-When studying cross-sections or large particles of powders, it
-is sometimes desirable to make low-power sketches of the specimen.
-In most cases, however, only sufficient time should be
-spent in studying the specimen to give an idea of the size, structure,<span class="pagenum" id="Page_26">[26]</span>
-and general arrangement or plan or structure if a section
-of a plant, or, if a powder, to note its striking characters. All
-the finer details of structure are best brought out with the
-high-power objective in position.</p>
-
-
-<p>In <span class="bold">placing the high-power objective in position</span>, it is first
-necessary to raise the body by the coarse adjustment; then
-open the iris diaphragm, and lower the body until the objective
-is within about one-eighth of an inch of the slide. Now raise
-the tube by the fine adjustment until the object is in focus,
-then gradually close the iris diaphragm until a clear definition
-of the object is obtained. Now proceed to make an accurate
-sketch of the object or objects being studied.</p>
-
-
-<p>In <span class="bold">using the water or oil-immersion objectives</span> it is first
-necessary to place a drop of distilled water or oil, as the case
-may be, immediately over the specimen, then lower the body
-by the coarse adjustment until the lens of the objective touches
-the water or the oil. Raise the tube, regulate the light by the
-iris diaphragm, and proceed as if the high-power objectives were
-in position.</p>
-
-<p>The water or oil should be removed from the objectives and
-from the slide when not in use.</p>
-
-<p>After the higher-powered objective has been used, the body
-should be raised, and the low-power objective placed in position.
-If the draw-tube has been drawn out during the examination
-of the object, replace it, but be sure to hold one hand on the
-nose-piece so as to prevent scratching the objective and Abbé
-condenser by their coming in forceful contact. Lastly, clean
-the mirror with a soft piece of linen. In returning the microscope
-to its case, or to the shelf, grasp the limb, or the pillar,
-firmly and carry as nearly vertical as possible in order not to
-dislodge the eye-piece.</p>
-
-<h4 id="ILLUMINATION">ILLUMINATION</h4>
-
-<p>The illumination for microscopic work may be from natural
-or <a id="ARTIFICIAL_SOURCES">artificial sources</a>.</p>
-
-<div class="figcenter illowp86" id="fig30" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig30.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 30.</span>&mdash;Micro Lamp</div>
-</div>
-
-<p>It has been generally supposed that the best possible illumination
-for microscopic work is diffused sunlight obtained from
-a northern direction. No matter from what direction diffused<span class="pagenum" id="Page_27">[27]</span>
-sunlight is obtained, it will be found suitable for microscopic
-work. In no case should direct sunlight be used, because it
-will be found blinding in its effects upon the eyes. Natural
-illumination&mdash;diffused sunlight&mdash;varies so greatly during the
-different months of the year, and even during different periods
-of the day, that individual workers are resorting more and more
-to artificial illumination. The particular advantage of such
-illumination is due to the fact that its quality and intensity
-are uniform at all times. There are many ways of securing
-such artificial illumination, no one of which has any particular
-advantage over the other. Some workers use an ordinary gas
-or electric light with a color screen placed in the sub-stage
-below the iris diaphragm. In other cases a globe filled with a
-weak solution of copper sulphate is placed in such a way between
-the source of light and the microscope that the light is
-focused on the mirror. Modern mechanical ingenuity has devised,
-however, a number of more convenient micro lamps
-(Fig. 30). These lamps are a combination of light and screen.
-In some forms a number of different screens come with each
-lamp, so that it is possible to obtain white-, blue-, or dark-ground<span class="pagenum" id="Page_28">[28]</span>
-illumination. The type of the screen used will be varied according
-to the nature of the object studied.</p>
-
-<h4 id="CARE_OF_THE_MICROSCOPE">CARE OF THE MICROSCOPE</h4>
-
-<p>If possible, the microscope should be stored in a room of
-the same temperature as that in which it is to be used. In
-any case, avoid storing in a room that is cooler than the place
-of use, because when it is brought into a warmer room, moisture
-will condense on the ocular objectives and mirrors.</p>
-
-<p>Before beginning work remove all moisture, dust, etc., from
-the inner and outer lenses of the ocular, the objectives, the
-Abbé condenser, and the mirror by means of a piece of soft,
-old linen. When the work is finished the optical parts should
-be thoroughly cleaned.</p>
-
-<p>If reagents have been used, be sure that none has got on
-the objectives or the Abbé condenser. If any reagent has got
-on these parts, wash it off with water, and then dry them thoroughly
-with soft linen.</p>
-
-<p>The inner lenses of the eye-pieces and the under lens of the
-Abbé condenser should occasionally be cleaned. The mechanical
-parts of the stand should be cleaned if dust accumulates, and
-the movable surfaces should be oiled occasionally. Never
-attempt to make new combinations of the ocular or objective
-lenses, or transfer the objectives or ocular from one microscope
-to another, because the lenses of any given microscope form a
-perfect lens system, and this would not be the case if they were
-transferred. Keep clean cloths in a dust-proof box. Under no
-circumstances touch any of the optical parts with your fingers.</p>
-
-<h4 id="PREPARATION_OF_SPECIMENS_FOR_CUTTING">PREPARATION OF SPECIMENS FOR CUTTING</h4>
-
-<p>Most drug plants are supplied to pharmacists in a dried
-condition. It is necessary, therefore, to boil the drug in water,
-the time varying from a few minutes, in the case of thin leaves
-and herbs, up to a half hour if the drug is a thick root or woody
-stem. If a green (undried) drug is under examination, this
-first step is not necessary.</p>
-
-<p>If the specimen to be cut is a leaf, a flower-petal, or other<span class="pagenum" id="Page_29">[29]</span>
-thin, flexible part of a plant, it may be placed between pieces
-of elder pith or slices of carrot or potato before cutting.</p>
-
-<h5>SHORT PARAFFIN PROCESS</h5>
-
-<p>In most cases, however, more perfect sections will be obtained
-if the specimens are embedded in paraffin, by the quick
-paraffin process, which is easily carried out.</p>
-
-<p>After boiling the specimen in water, remove the excess of
-moisture from the outer surface with filter paper or wait until
-the water has evaporated. Next make a mould of stiff cardboard
-and pour melted paraffin (melting at 50 or 60 degrees)
-into the mould to a height of about one-half inch, when the
-paraffin has solidified. This may be hastened by floating it
-on cool or iced water instead of allowing it to cool at room
-temperature.</p>
-
-<p>The specimens to be cut are now placed on the paraffin,
-with glue, if necessary, to hold them in position, and melted
-paraffin poured over the specimens until they are covered to a
-depth of about one-fourth of an inch. Cool on iced water,
-trim off the outer paraffin to the desired depth, and the Specimen
-will be in a condition suitable for cutting.</p>
-
-<p>Good workable sections may be cut from specimens embedded
-by this quick paraffin method. After a little practice the entire
-process can be carried out in less than an hour. This method
-of preparing specimens for cutting will meet every need of the
-pharmacognosist.</p>
-
-<h5>LONG PARAFFIN PROCESS</h5>
-
-<p>In order to bring out the structure of the <span class="bold">protoplast</span> (living
-part of the cell), it will be necessary to begin with the living
-part of the plant and to use the long paraffin method or the
-collodion method.</p>
-
-<p>Small fragments of a leaf, stem, or root-tip are placed in
-chromic-acid solution, acetic alcohol, picric acid, chromacetic
-acid, alcohol, etc., depending upon the nature of the specimen
-under observation. The object of placing the living specimen
-in such solutions is to kill the protoplast suddenly so that the
-parts of the cell will bear the same relationship to each other<span class="pagenum" id="Page_30">[30]</span>
-that they did in the living plant, and to fix the parts so killed.</p>
-
-<p>After the fixing process is complete, the specimen is freed
-of the fixing agent by washing in water. From the water-bath
-the specimens are transferred successively to 10, 20, 40, 60, 70,
-80, 90, and finally 100 per cent alcohol. In this 100 per cent
-alcohol-bath the last traces of moisture are removed. The
-length of time required to leave the specimens in the different
-percentages of alcohols varies from a few minutes to twenty-four
-hours, depending upon the size and the nature of the specimen.</p>
-
-<div class="figcenter illowp86" id="fig31" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig31.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 31.</span>&mdash;Paraffin-embedding Oven</div>
-</div>
-
-<p>After dehydration the specimen is placed in a clearing agent&mdash;chloroform
-or xylol&mdash;both of which are suitable when embedding
-in paraffin. The clearing agents replace the alcohol in
-the cells, and at the same time render the tissues transparent.
-From the clearing agent the specimen is placed in a weak solution
-of paraffin, dissolved xylol, or chloroform. The strength of
-the paraffin solution is gradually increased until it consists
-of pure paraffin. The temperature of the paraffin-embedding<span class="pagenum" id="Page_31">[31]</span>
-oven (Fig. 31) should not be much higher than the melting-point
-of the paraffin.</p>
-
-<p>The specimen is now ready to be embedded. First make a
-mould of cardboard or a lead-embedding frame (Fig. 32), melt
-the paraffin, and then place the
-specimen in a manner that will
-facilitate cutting. Remove the
-excess of paraffin and cut when
-desired.</p>
-
-<div class="figcenter illowp100" id="fig32" style="max-width: 28.125em;">
-  <img class="w100 p1" src="images/fig32.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 32.</span>&mdash;Paraffin Blocks</div>
-</div>
-
-<p>In using the collodion method
-for embedding fibrous specimens,
-as wood, bark, roots, etc.,
-the specimen is first fixed with picric acid, washed with water,
-cleared in ether-alcohol, embedded successively in two, five,
-and twelve per cent ether-alcohol collodion solution, and finally
-embedded in a pure collodion bath.</p>
-
-<h4 id="CUTTING_SECTIONS">CUTTING SECTIONS</h4>
-
-<p>Specimens prepared as described above may be cut with a
-hand microtome or a machine microtome.</p>
-
-<h5 id="HAND_MICROTOME">HAND MICROTOME</h5>
-
-<p>In cutting sections by a <span class="bold">hand microtome</span>, it is necessary to
-place the specimen, embedded in paraffin or held between
-pieces of elder pith, carrot, or potato, over the second joints
-of the fingers, then press the first joints firmly upon the specimen
-with the thumb pressed against it. If they are correctly
-held, the specimens will be just above the level of the finger and
-the end of the thumb, and the joint will be below the level of
-the finger.</p>
-
-<div class="figcenter illowp100" id="fig33" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig33.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 33.</span>&mdash;Hand Microtome</div>
-</div>
-
-<p>Hold the section cutter (Fig. 33) firmly in the hand with<span class="pagenum" id="Page_32">[32]</span>
-the flat surface next to the specimen. While cutting the section,
-press your arm firmly against your chest, and bend the
-wrist nearly at right angles to the arm. Push the cutting edge
-of the microtome toward the body and through the specimen
-in such a way as to secure as thin a section as possible. Do
-not expect to obtain nice, thin sections during the first or second
-trials, but continued practice will enable one to become quite
-efficient in cutting sections in this manner.</p>
-
-<p>When the examination of drugs is a daily occurrence, the
-above method will be found highly satisfactory.</p>
-
-<h5 id="MACHINE_MICROTOMES">MACHINE MICROTOMES</h5>
-
-<p>When a number of sections are to be prepared from a given
-specimen, it is desirable to cut the sections on a machine microtome,
-particularly when the sections are to be prepared for the
-use of students, in which case they should be as uniform as
-possible.</p>
-
-<p>Great care should be exercised in cutting sections with a
-machine microtome&mdash;first, in the selection of the type of the
-microtome; and secondly, in the style of knife used in cutting.</p>
-
-<p>For soft tissues embedded in paraffin or collodion, the <span class="bold">rotary
-microtome</span> with vertical knife will give best results. The thickness
-of the specimen is regulated by mechanical means, so that
-in cutting the sections it is only necessary to turn a crank and
-remove the specimens from the knife-edge, unless there is a
-ribbon-carrier attachment. If the sections are being cut from
-a specimen embedded by the quick paraffin method, it is best
-to drop the section in a metal cup partly filled with warm water.
-This will cause the paraffin to straighten out, and the specimen
-will uncoil. After sufficient specimens have been cut, the
-cup should be placed in a boiling-water bath until the paraffin
-surrounding the sections melts and floats on the water. Before
-removing the specimen from the water-bath, it is advisable to
-shake the glass vigorously in order to cause as many specimens
-as possible to settle to the bottom of the cup. The cup is then
-placed in iced water or set aside until the paraffin has solidified.
-The cake-like mass is then removed from the cup, and the sections
-adhering to its under surface are removed by lifting them
-carefully off with the flat side of the knife and transferring them,<span class="pagenum" id="Page_33">[33]</span>
-together with the sections at the bottom of the cup, to a wide-mouth
-bottle, and covered with alcohol, glycerine, and water
-mixture; or if it is desired to stain the specimens, they should
-be placed in a weak alcoholic solution.</p>
-
-<p>Specimens having a hard, woody texture should be cut on
-a <span class="bold">sliding microtome</span> by means of a special wood knife, which
-is especially tempered to cut woody substances. Woody roots,
-wood, or thick bark may be cut readily on this microtome when
-they have been embedded by the quick paraffin process. The
-knife in the sliding microtome is placed in a horizontal position,
-slanting so that the knife-edge is drawn gradually across the
-specimen. After cutting, the sections are treated as described
-above.</p>
-
-<p>The thickness of the sections is regulated by mechanical
-means. After a section has been cut, the block containing the
-specimen is raised by turning a thumb-screw. In this microtome
-the knife, as in the rotary type, is fixed, and the block containing
-the specimen is movable.</p>
-
-<p>If the specimen has been infiltrated with, and embedded in,
-paraffin or collodion, the treatment of the sections after cutting
-should be different.</p>
-
-<p>In the case of paraffin, the sections are fastened directly to
-the slide, and the paraffin is dissolved by either chloroform or
-xylol. The specimen is then placed in 100, 95, and 45 per cent
-alcohol, and then washed in water. These sections are now
-stained with water-stains, brought back through alcohol, cleared,
-and mounted in Canada balsam.</p>
-
-<p>If alcoholic stains are used, it will not be necessary to dehydrate
-before staining, and the dehydration after staining will
-also be eliminated.</p>
-
-<p>Sections infiltrated with collodion are either stained directly
-without removing the collodion or after removal.</p>
-
-<h5>FORMS OF MICROTOMES</h5>
-
-<p>The <span class="bold">hand cylinder microtome</span> (Fig. 34) consists of a cylindrical
-body. The clamp for holding the specimen is near the top
-below the cutting surface. At the lower end is attached a micrometer
-screw with a divided milled head. When moved forward
-one division, the specimen is raised 0.01 mm. This micrometer<span class="pagenum" id="Page_34">[34]</span>
-screw has an upward movement of 10 mm. The cutting surface
-consists of a cylindrical glass ring.</p>
-
-<div class="figcenter illowp80" id="fig34_35-t" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig34_35-t.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 34.</span>&mdash;Hand Cylinder Microtome</div>
-</div>
-
-<div class="figcenter illowp77" id="fig34_35-b" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig34_35-b.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 35.</span>&mdash;Hand Table Microtome</div>
-</div>
-
-<p>The <span class="bold">hand table microtome</span> (Fig. 35) is provided with a clamp,
-by which it may be attached to the edge of a table or desk.<span class="pagenum" id="Page_35">[35]</span>
-The cutting surface consists of two separated but parallel glass
-benches. The object is held by a clamp and is raised by a
-micrometer screw, which, when moved through one division by
-turning the divided head, raises the specimen 0.01 mm.</p>
-
-<p>The <span class="bold">sliding microtome</span> has a track of 250 mm. The object
-is held by a clamp and its height regulated by hand. The disk
-regulating the micrometer screw is divided into one hundred
-parts. When this is turned through one division, the object is
-raised 0.005 mm. or 5 microns, at the same time a clock-spring
-in contact with teeth registers by a clicking sound. If the disk
-is turned through two divisions, there will be two clicks, etc.
-In this way is regulated the thickness of the sections cut. When
-the micrometer screw has been turned through the one hundred
-divisions, it must be unscrewed, the specimen raised, and the
-steps of the process repeated. The knife is movable and is
-drawn across the specimen in making sections.</p>
-
-<div class="figcenter illowp100" id="fig36" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig36.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 36.</span>&mdash;Base Sledge Microtome</div>
-</div>
-
-<p>The <span class="bold">base sledge microtome</span> (Fig. 36) has a heavy iron base
-which supports a sliding-way on which the object-carrier moves.
-The object-carrier is mounted on a solid mass of metal, and is
-provided with a clamp for holding the object. The object is
-raised by turning a knob which, when turned once, raises the
-specimen one to twenty microns, according to how the feeding
-mechanism is set.</p>
-
-<p><span class="pagenum" id="Page_36">[36]</span></p>
-
-<p>Sections thicker than twenty microns may be obtained by
-turning the knob two or more times. The knife is fixed and is
-supported by two pillars, the base of which may be moved forward
-or backward in such a manner that the knife can be
-arranged with an oblique or right-angled cutting surface.</p>
-
-<div class="figcenter illowp95" id="fig37" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig37.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 37.</span>&mdash;Minot Rotary Microtome</div>
-</div>
-
-<p>The <span class="bold">Minot rotary microtome</span> (Fig. 37) has a fixed knife, held
-in position by two pillars, and a movable object-carrier. The
-object is firmly secured by a clamp, and it is raised by a micrometer
-screw. The screw is attached to a wheel having five
-hundred teeth on its periphery. A pawl is adjusted to the teeth
-in such a way that, when moved by turning a wheel to which
-it is attached, specimens varying from one to twenty-five microns
-in thickness may be cut, according to the way the adjusting disk
-is set. When the mechanism has been regulated and the object
-adjusted for cutting, it is only necessary to turn a crank in
-cutting sections.</p>
-
-<h5>CARE OF MICROTOMES</h5>
-
-<p>When not in use, microtomes should be protected from dust,
-and all parts liable to friction should be oiled.</p>
-
-<p><span class="pagenum" id="Page_37">[37]</span></p>
-
-<p>Microtome knives should be honed as often as is necessary
-to insure a proper cutting edge. After cutting objects, the
-knives should be removed, cleaned, and oiled.</p>
-
-<p>It should be kept clearly in mind that special knives are
-required for cutting collodion, paraffin, and frozen and woody
-sections. The cutting edges of the different knives vary considerably,
-as is shown in the preceding cuts.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_38">[38]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_V">CHAPTER V<br />
-<span class="fs80">REAGENTS</span></h3>
-</div>
-
-<p>Little attention is given in the present work to micro-chemical
-reactions for the reason that their value has been much overrated
-in the past. A few reagents will be found useful, however,
-and these few are given, as well as their special use. They are
-as follows:</p>
-
-<h4>LIST OF REAGENTS</h4>
-
-<p><span class="bold">Distilled Water</span> is used in the alcohol, glycerine, and water
-mixture as a general mounting medium. It is used when warm
-as a test for inulin and it is used in preparing various reagents.</p>
-
-<p><span class="bold">Glycerine</span> is used in preparing the alcohol, glycerine, and
-water mixture, in testing for aleurone grains, and as a temporary
-mounting medium.</p>
-
-<p><span class="bold">Alcohol</span> is used in preparing the alcohol, glycerine, and water
-mixture, in testing for volatile oils.</p>
-
-<p><span class="bold">Acetic Acid</span>. Both dilute and strong solutions are used in
-testing for aleurone grains, cystoliths, and crystals of calcium
-oxalate.</p>
-
-<p><span class="bold">Hydrochloric Acid</span> is used in connection with phloroglucin
-as a test for lignin and as a test for calcium oxalate.</p>
-
-<p><span class="bold">Ferric Chloride Solution</span> is used as a test for tannin.</p>
-
-<p><span class="bold">Sulphuric Acid</span> is used as a test for calcium oxalate.</p>
-
-<p><span class="bold">Tincture Alkana</span> is used when freshly prepared by macerating
-the granulated root with alcohol and filtering, as a test
-for resin.</p>
-
-<p><span class="bold">Sodium Hydroxide</span>. A five per cent solution is used as a
-test for suberin and as a clearing agent.</p>
-
-<p><span class="bold">Copper Ammonia</span> is used as a test for cellulose.</p>
-
-<p><span class="bold">Ammonical Solution of Potash</span> is used as a test for fixed
-oils. The solution is a mixture of equal parts of a saturated
-solution of potassium hydroxide and stronger ammonia.</p>
-
-<p><span class="pagenum" id="Page_39">[39]</span></p>
-
-<p><span class="bold">Oil of Cloves</span> is used as a clearing fluid for sections preparatory
-to mounting in Canada balsam.</p>
-
-<p><span class="bold">Canada Balsam</span> is used as a permanent mounting medium
-for dehydrated specimens, and as a cement for ringing slides.</p>
-
-<p><span class="bold">Paraffin</span> is used for general embedding and infiltrating.</p>
-
-<p><span class="bold">Lugol’s Solution</span> is used as a test for starch and for aleurone
-grains and proteid matters.</p>
-
-<p><span class="bold">Osmic Acid</span>. A two per cent solution is used as a test for
-fixed oils.</p>
-
-<p><span class="bold">Alcohol, Glycerine, and Water Mixture</span> is used as a temporary
-mounting medium and as a qualitative test for fixed oils.</p>
-
-<p><span class="bold">Chlorzinc Iodide</span> is used as a test for suberin, lignin, cellulose,
-and starch.</p>
-
-<p><span class="bold">Analine Chloride</span> is used as a test for lignified cell walls of
-bast fibres and of stone cells.</p>
-
-<p><span class="bold">Phloroglucin</span>. A one per cent alcoholic solution is used in
-connection with hydrochloric acid as a test for lignin.</p>
-
-<p><span class="bold">Hæmatoxylin-Delifields</span> is used as a test for cellulose.</p>
-
-<div class="figcenter illowp100" id="fig38" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig38.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 38.</span>&mdash;Reagent Set</div>
-</div>
-
-<h5 id="REAGENT_SET">REAGENT SET</h5>
-
-<p>Each worker should be provided with a set of <span class="bold">reagent bottles</span>
-(Fig. 38). Such a set may be selected according to the taste
-of the individual, but experience has shown that a 30 c.c. bottle
-with a ground-in pipette and a rubber bulb is preferable to other
-types. In such forms the pipettes are readily cleaned, and the
-rubber bulbs can be replaced when they become old and brittle.<span class="pagenum" id="Page_40">[40]</span>
-The entire set should be protected from dust by keeping it in a
-case, the cover of which should be closed when the set is not
-in use.</p>
-
-<h5 id="MEASURING_CYLINDER">MEASURING CYLINDER</h5>
-
-<p>In order accurately to measure micro-chemical reagents, it
-is necessary to have a standard 50 c.c. cylinder (Fig. 39) graduated
-to c.c.’s. Such a cylinder should form a part of the reagent set.</p>
-
-<div class="figcenter illowp77" id="fig39-fig40" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig39-fig40.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 39</span>.&mdash;Measuring Cylinder<span class="smcap pad8">Fig. 40.</span>&mdash;Staining Dish</div>
-</div>
-
-<h5>STAINING DISHES</h5>
-
-<p>There is a great variety of <span class="bold">staining dishes</span> (Fig. 40), but
-for general histological work a glass staining dish with groves
-for holding six or more slides and a glass cover is most desirable.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_41">[41]</span></p>
-
-<h3 class="nobreak" id="CHAPTER_VI">CHAPTER VI<br />
-<span class="fs80">HOW TO MOUNT SPECIMENS</span></h3>
-</div>
-
-<p>The method of procedure in mounting specimens for study
-varies according to the nature of the specimen, its preliminary
-treatment, and the character of the mount to be made. As to
-duration, mounts are either temporary or permanent.</p>
-
-<h4 id="TEMPORARY_MOUNTS">TEMPORARY MOUNTS</h4>
-
-<p>In preparing a <span class="bold">temporary mount</span>, place the specimen in the
-centre of a clean slide and add two or more drops of the temporary
-mounting medium, which may be water, or a mixture
-of equal parts of alcohol, glycerine, and water, or some micro-chemical
-reagent, as weak Lugol’s solution, solution of chloral
-hydrate, etc. Cover this with a cover glass and press down
-gently. Remove the excess of the mounting medium with a
-piece of blotting paper. Now place the slide on the stage and
-proceed to examine it. Such mounts can of course be used only
-for short periods of study; and when the period of observation
-is finished, the specimen should be removed and the slide washed,
-or the slide washing may be deferred until a number of such
-slides have accumulated. At any rate, when the mounting
-medium dries, the specimen is no longer suitable for observation.</p>
-
-<h4 id="PERMANENT_MOUNTS">PERMANENT MOUNTS</h4>
-
-<p>Permanent mounts are prepared in much the same way as
-temporary, but of course the mounting medium is different.
-The kind of permanent mounting medium used depends upon
-the previous treatment of the specimen. If the specimen has
-been preserved in alcohol or glycerine and water, it is usually
-mounted in glycerine jelly. If the specimen in question is a
-powder, it is placed in the centre of the slide and a drop or two<span class="pagenum" id="Page_42">[42]</span>
-of glycerine, alcohol, and water mixture added, unless the
-powder was already in suspension in such a mixture. Cut a
-small cube of glycerine jelly and place it in the centre of the
-powder mixture. Lift up the slide by means of pliers, or grasp
-the two edges between the thumb and finger and hold over a
-small flame of an alcohol lamp, or place on a steam-bath until
-the glycerine jelly has melted. Next sterilize a dissecting needle,
-cool, and mix the powder with the glycerine jelly, being careful
-not to lift the point of the needle from the slide during the
-operation. If the mixing has been carefully done, few or no
-air-bubbles will be present; but if they are present, heat the
-needle, and while it is white hot touch the bubbles with its
-point, and they will disappear. Now take a pair of forceps and,
-after securing a clean cover glass near the edge, pass them three
-times through the flame of the alcohol lamp. While holding it
-in a slanting position, touch one side of the powder mixture and
-slowly lower the cover glass until it comes in complete contact
-with the mixture. Now press gently with the end of the needle-handle,
-and set it aside to cool. When it is cool, place a neatly
-trimmed label on one end of the slide, on which write the name
-of the specimen, the number of the series of which it is to form
-a part, etc. Any excess of glycerine jelly, which may have
-been pressed out from the edges of the cover glass, should not
-be removed at once, but should be allowed to remain on the
-slide for at least one month in order to allow for shrinkage due
-to evaporation. At the end of a month remove the glycerine
-jelly by first passing the blade of a knife, held in a vertical
-position, the back of the knife being next to the slide, around
-the edge of the cover glass. After turning the knife-blade so
-that the flat side is in contact with slide, remove the jelly outside
-of the cover glass. Any remaining fragments should be removed
-with a piece of old linen or cotton cloth. Finally, ring the edge
-of the cover glass with microscopical cement, of which there
-are many types to be had. If the cleaning has been done
-thoroughly, there is no better ringing cement than Canada
-balsam.</p>
-
-<p>In mounting cross-sections, the method of procedure is
-similar to the above, with the exception that the glycerine jelly
-is placed at the side of the specimen and not in the centre.<span class="pagenum" id="Page_43">[43]</span>
-While melting the jelly, incline the slide in order to allow the
-melted glycerine jelly to flow gradually over the specimen, thus
-replacing the air contained in the cells and intercellular spaces.
-Finish the mounting as directed above, but under no conditions
-should you stir the glycerine jelly with the section.</p>
-
-<p>If specimens, after having been embedded in paraffin or
-collodion, are cut, cleared, stained, and dehydrated, they are
-usually mounted in Canada balsam. A small drop of this substance,
-which may be obtained in collapsible tubes, is placed
-at one side of the specimen. While inclining the slide, gently
-heat until the Canada balsam covers the specimen. Secure a
-cover glass by the aid of pliers, pass it through the flame three
-times, and lower it slowly while holding it in an inclined position.
-Press gently on the cover glass with the needle-handle, and keep
-in a horizontal position for twenty-four hours, then place directly
-in a slide box or cabinet, since no sealing is required.</p>
-
-<p>Glycerine is sometimes used to make permanent mounts, but
-it is unsatisfactory, because the cover glass is easily removed
-and the specimen spoiled or lost, unless ringed&mdash;a procedure
-which is not easily accomplished. If the specimen is to be
-mounted in glycerine, it must first be placed in a mixture of
-alcohol, glycerine, and water, and then transferred to glycerine.
-Lactic acid is another permanent liquid-mounting medium,
-which is unsatisfactory in the same way as glycerine, but like
-glycerine, there are certain special cases where it is desirable
-to use it. When this is used, the slides should be kept in a
-horizontal position, unless ringed.</p>
-
-<h5 id="COVER_GLASSES">COVER GLASSES</h5>
-
-<p>Great care should be used In the selection of <span class="bold">cover glasses</span>,
-however, not only as regards their shape but as to their thickness.
-The standard tube length of the different manufacturers makes
-an allowance of a definite thickness for cover glasses. It is
-necessary, therefore, to use cover glasses made by the manufacturer
-of the microscope in use.</p>
-
-<p>Cover glasses are either square or round. Of each there are
-four different thicknesses and two different sizes. The standard
-thicknesses are:<span class="pagenum" id="Page_44">[44]</span>
-The small size is designated three-fourths and the large
-size seven-eighths.</p>
-
-<div class="figcenter illowp100" id="fig41_43" style="max-width: 50em;">
-  <img class="w100 p1" src="images/fig41_43.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 41.</span>&mdash;Round Cover Glass <span class="smcap pad2">Fig. 42.</span>&mdash;Square Cover Glass  <span class="smcap pad4">Fig. 43.</span>&mdash;Rectangular Cover Glass</div>
-</div>
-
-<p><span class="bold">Cover glasses</span> are circular (Fig. 41), square (Fig. 42), or
-rectangular (Fig. 43) pieces of transparent glass used in covering
-the specimens mounted on glass slides. A few years ago much
-difficulty was experienced in obtaining uniformly thick and
-transparent cover glasses, but no such difficulty is experienced
-to-day. The type of cover glass used depends largely upon the
-character of the specimen to be mounted. The square and
-rectangular glasses are selected when a series of specimens are
-to be mounted, but in mounting powdered drugs and histological
-specimens the round cover glasses are preferable because they
-are more sightly and more readily cleaned and rinsed.</p>
-
-<h5 id="GLASS_SLIDES">GLASS SLIDES</h5>
-
-<div class="figcenter illowp100" id="fig44" style="max-width: 28.125em;">
-  <img class="w100 p1" src="images/fig44.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 44.</span>&mdash;Glass Slide</div>
-</div>
-
-<p><span class="bold">Glass slides</span> (Fig. 44) are rectangular pieces of transparent
-glass used as a mounting surface for microscopic objects. The
-slides are usually three inches long by one inch wide, and they
-should be composed of white glass, and they should have ground<span class="pagenum" id="Page_45">[45]</span>
-and beveled edges. Slides should be of uniform thickness, and
-they should not become cloudy upon standing.</p>
-
-<h5 id="FORCEPS">SLIDE AND COVER-GLASS FORCEPS</h5>
-
-<p>Slides and cover glasses should be grasped by their edges.
-To the beginner this is not easy. In order to facilitate holding
-slides and cover glasses during the mounting process, one may
-use a slide and a cover-glass <span class="bold">forceps</span>. The slide forceps consists
-of wire bent and twisted in such a way that it holds a slide
-firmly when attached to its two edges.</p>
-
-<div class="figcenter illowp100" id="fig45" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig45.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 45.</span>&mdash;Histological Forceps</div>
-</div>
-
-<div class="figcenter illowp100" id="fig46" style="max-width: 31.25em;">
-  <img class="w100 p2" src="images/fig46.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 46.</span>&mdash;Forceps</div>
-</div>
-
-<div class="figcenter illowp100" id="fig47" style="max-width: 31.25em;">
-  <img class="w100 p2" src="images/fig47.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 47.</span>&mdash;Sliding-pin Forceps</div>
-</div>
-
-<p>There are various forms of cover-glass holders, but only two
-types as far as the method of securing the cover glass is concerned.
-First, there are the bacteriological and the histological
-forceps (Fig. 45), which are self-closing. The two blades of such
-forceps must be forced apart by pressure in securing the cover
-glass. The second type of forceps is that in which the two
-blades are normally separated (Fig. 46), it being necessary to
-press the blades to either side of the cover glass in order to
-secure and hold it. There is a modification of this type of
-forceps which enables one to lock the blades by means of a sliding
-pin (Fig. 47), after the cover glass has been secured. It is<span class="pagenum" id="Page_46">[46]</span>
-well to accustom oneself to one type, for by so doing one may
-become dexterous in its use.</p>
-
-<h5 id="NEEDLES">NEEDLES</h5>
-
-<div class="figcenter illowp100" id="fig48" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig48.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 48.</span>&mdash;Dissecting Needle</div>
-</div>
-
-<p>Two <span class="bold">dissecting needles</span> (Fig. 48) should form a part of the
-histologist’s mounting set. The handles may be of any material,
-but the needle should be of tempered steel and about two inches
-long.</p>
-
-<h5 id="SCISSORS">SCISSORS</h5>
-
-<div class="figcenter illowp100" id="fig49" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig49.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 49.</span>&mdash;Scissors</div>
-</div>
-
-<p>Almost any sort of <span class="bold">scissors</span> (Fig. 49) will do for histology
-work, but a small scissors with fine pointed blades, are preferred.
-Scissors are useful in trimming labels and in cutting strips of
-leaves and sections of fibrous roots that are to be embedded
-and cut.</p>
-
-<h5 id="SCALPELS">SCALPELS</h5>
-
-<div class="figcenter illowp100" id="fig50" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig50.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 50.</span>&mdash;Scalpels</div>
-</div>
-
-<p><span class="bold">Scalpels</span> (Fig. 50) have steel blades and ebony handles.
-These vary in regard to size and quality of material. The
-cheaper grades are quite as satisfactory, however, as the more
-expensive ones, and for general use a medium-sized blade and
-handle will be found most useful.</p>
-
-<h5 id="TURNTABLE">TURNTABLE</h5>
-
-<div class="figcenter illowp100" id="fig51" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig51.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 51.</span>&mdash;Turntable</div>
-</div>
-
-<p>Much time and energy may be saved by ringing slides on a
-<span class="bold">turntable</span> (Fig. 51). There is a flat surface upon which to rest
-the hand holding the brush with cement, and a revolving table<span class="pagenum" id="Page_47">[47]</span>
-upon which the slide to be ringed is held by means of two clips.
-In ringing slides, it is only necessary to revolve the table, and
-at the same time to transfer the cement to the edge of the
-cover glass from the brush held in the hand.</p>
-
-<h5 id="LABELING">LABELING</h5>
-
-<p>There are many ways of <span class="bold">labeling slides</span>, but the best method
-is to place on the label the name of the specimen, the powder<span class="pagenum" id="Page_48">[48]</span>
-number, and the box, the tray or cabinet number. For
-example:</p>
-
-<p class="center">Powdered Arnica Flowers<br />
-No. 80&mdash;Box A&mdash;600.</p>
-
-<h4 id="PRESERVATION_OF_MOUNTED_SPECIMENS">PRESERVATION OF MOUNTED SPECIMENS</h4>
-
-<div class="figcenter illowp68" id="fig52" style="max-width: 28.6875em;">
-  <img class="w100 p1" src="images/fig52.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 52.</span>&mdash;Slide Box</div>
-</div>
-
-<div class="figcenter illowp85" id="fig53" style="max-width: 31.25em;">
-  <img class="w100 p1" src="images/fig53.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 53.</span>&mdash;Slide Tray</div>
-</div>
-
-<p>Accurately mounted, labeled, and ringed slides should be
-filed away for future study and reference. Such <span class="bold">filing</span> may
-be done in slide boxes, in slide trays, or in cabinets. Slide
-boxes are to be had of a holding capacity varying from one to<span class="pagenum" id="Page_49">[49]</span>
-one hundred slides. For general use, slide boxes (Fig. 52) holding
-one hundred slides will be found most useful. Some workers
-prefer trays (Fig. 53), because of the saving of time in selecting
-specimens. Trays hold twenty slides arranged in two rows.
-The cover of the tray is divided into two sections so that, if
-desired, only one row of slides is uncovered at a time. Slide
-cabinets (Fig. 54) are particularly desirable for storing large
-individual collections, particularly when the slides are used
-frequently for reference. Large selections of slides should be
-numbered and card indexed in order to facilitate finding.</p>
-
-<div class="figcenter illowp87" id="fig54" style="max-width: 37.5em;">
-  <img class="w100 p1" src="images/fig54.jpg" alt="" />
-  <div class="caption"><span class="smcap">Fig. 54.</span>&mdash;Slide Cabinet</div>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<p><span class="pagenum" id="Page_50">[50]</span><br />
-<span class="pagenum"><a name="Page_51" id="Page_51">[51]</a></span><br />
-<span class="pagenum"><a name="Page_52" id="Page_52">[52]</a></span></p>
-
-<div class="chapter">
-<h2 class="nobreak p8 pb10" id="Part_II">Part II<br />
-<span class="fs80">TISSUES CELLS, AND CELL CONTENTS</span></h2>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_53">[53]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_I">CHAPTER I<br />
-<span class="fs80">THE CELL</span></h3>
-</div>
-
-<p>The <span class="bold">cell</span> is the unit of structure of all plants. In fact the
-cell is the plant in many of the lower forms&mdash;so called unicellular
-plants. All plants, then, consist of one or more cells.</p>
-
-<p>While cells vary greatly in size, form, color, contents, and
-function, still in certain respects their structure is identical.</p>
-
-<h4 id="TYPICAL_CELL">TYPICAL CELL</h4>
-
-<p>The typical vegetable cell is composed of a living portion or
-<span class="bold">protoplast</span> and an external covering, or <span class="bold">wall</span>. The protoplast includes
-everything within the wall. It is made up of a number
-of parts, each part performing certain functions yet harmonizing
-with the work of the cell as a whole. The protoplast (protoplasm)
-is a viscid substance resembling the white of an egg.
-The protoplast, when unstained and unmagnified, appears
-structureless, but when stained with dyes and magnified, it is
-found to be highly organized. The two most striking parts of
-the protoplast are the <span class="bold">cytoplasm</span> and the <span class="bold">nucleus</span>. The part
-of the protoplast lining the innermost part of the wall is the
-<span class="bold">ectoplast</span>, which is less granular and slightly denser than most
-of the <span class="bold">cytoplasm</span>. The cytoplasm is decidedly granular in
-structure.</p>
-
-<p>In the cytoplasm occurs one or more cavities, <span class="bold">vacuoles</span>, filled
-with <span class="bold">cell sap</span>. Embedded in the cytoplasm are numerous
-<span class="bold">chromatophores</span>, which vary in color in the different cells, from
-colorless to yellow, to red, and to green. The <span class="bold">nucleus</span> is the
-seat of the vital activity of the cell, and the seat of heredity.
-The whole life and activity of the cell centre, therefore, in and
-about the nucleus.</p>
-
-<p><ins class="corr" id="tn53" title="Transcriber’s Note—“The outer portion of the nucelus” changed to “The outer portion of the nucleus”.">The outer portion of the nucleus</ins>
-consists of a thin membrane
-or wall. The membrane encloses numerous granular particles&mdash;<span class="bold">chromatin</span>&mdash;which<span class="pagenum" id="Page_54">[54]</span>
-are highly susceptible to organic stains.
-Among the granules are thread-like particles or <span class="bold">linin</span>. Near
-<ins class="corr" id="tn54" title="Transcriber’s Note—“the centre of the nucelus” changed to “the centre of the nucleus”.">the centre of the nucleus</ins>
-are one or more small rounded nucleoli.
-The liquid portion of the nucleus, filling the membranes and
-surrounding the chromatin, linin, and nucleoli, is the <span class="bold">nuclear
-sap</span>.</p>
-
-<p>Other cell contents characteristic of certain cells are crystals,
-starch, aleurone, oil, and alkaloids. The detailed discussion of
-these substances will be deferred until a later chapter.</p>
-
-<p>The <span class="bold">cell wall</span> which surrounds the protoplast is a product of
-its activity. The structure and composition of the wall of any
-given cell vary according to the ultimate function of the cell.
-The walls may be thin or thick, porous or non-porous, and
-colored or colorless. The composition of cell walls varies greatly.
-The majority of cell walls are composed of cellulose, in other
-cells of linin, in others of cutin, and in still others of suberin, etc.
-In the majority of cells the walls are laid down in a series of
-layers one over the other by apposition, similar to the manner
-of building a pile of paper from separate sheets. The first layer
-is deposited over the primary wall, formed during cell division;
-to this is added another layer, etc. A modification of this
-manner of growth is that in which the layers are built up one
-over the other, but the building is gradually done by the deposit
-of minute particles of cell-wall substance over the older deposits.
-Such walls are never striated, as is likely to be the case
-in cell walls formed by the first method. In other cells the walls
-are increased in thickness by the deposition of new wall material
-in the older membrane. The cell walls will be discussed more
-fully when the different tissues are studied in detail.</p>
-
-<h5>INDIRECT CELL DIVISION (KARYOKINESIS)</h5>
-
-<p>The purpose of cell division is to increase the number of cells
-of a tissue, an organ, an organism, or to increase the number of
-organisms, etc. Such cell divisions involve, first, an equal
-division of the protoplast and, secondly, the formation of a wall
-between the divided protoplasts. The first changes in structure
-of a cell undergoing division occur in the nucleus.</p>
-
-<p><span class="pagenum" id="Page_55">[55]</span></p>
-
-<h4 id="CHANGES_IN_A_CELL">CHANGES IN A CELL UNDERGOING DIVISION</h4>
-
-<p>The <span class="bold">linin threads</span> become thicker and shorter. The <span class="bold">chromatin
-granules</span> increase in size and amount; the threads and
-chromatin granules separate into a definite number of segments
-or <span class="bold">chromosomes</span> (Plate 1, Fig. 2). The nuclear membrane becomes
-invested with a fibrous protoplasmic layer which later
-separates and passes into either end of the cell, there forming
-the <span class="bold">polar caps</span> (Plate 1, Fig. 3).</p>
-
-<p>The <span class="bold">nuclear membrane</span> and the <span class="bold">nucleoli</span> disappear at about
-this time. Two fibres, one from each polar cap, become attached
-to opposite sides of the individual chromosomes. Other
-fibres from the two polar caps unite to form the <span class="bold">spindle fibres</span>,
-which thus extend from pole to pole. All these spindle fibres
-form the <span class="bold">nuclear spindle</span> (Plate 1, Fig. 5).</p>
-
-<p>The chromosomes now pass toward the division centre of
-the cell or <span class="bold">equatorial plane</span> and form, collectively, the <span class="bold">equatorial
-plate</span> (Plate 1, Fig. 5). At this point of cell division, the chromosomes
-are <span class="bold">U</span>-shaped, and the curved part of the chromosomes
-faces the equatorial plane. The chromosomes finally split into
-two equal parts (Plate 1, Fig. 6). The actual separation of the
-halves of chromosomes is brought about by the attached polar
-fibres, which contract toward the polar caps (Plate 1, Fig. 7).
-The chromosomes are finally drawn to the polar caps (Plate 1,
-Fig. 8). The chromosomes now form a rounded mass. They
-then separate into linin threads and chromatin granules. Nucleoli
-reappear, and nuclear sap forms. Finally, a nuclear membrane
-develops. The spindle fibres, which still extend from
-pole to pole, become thickened at the equatorial plane (Plate 1,
-Fig. 8), and finally their edges become united to form the <span class="bold">cell-plate</span>
-(Plate 1, Fig. 9), which extends across the cell, thus completely
-separating the mother cell into two daughter cells. After
-the formation of the cell-plate, the spindle fibres disappear.
-The cell becomes modified to form the <span class="bold">middle lamella</span>, on either
-side of which the daughter protoplast adds a cellulose layer.
-The ultimate composition of the middle lamella and the composition
-and structure of the cell wall will differ according to
-the function which the cell will finally perform.</p>
-
-<p><span class="pagenum" id="Page_56">[56]</span></p>
-
-<div class="figcenter illowp100" id="plate1" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate1.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 1</span><br />
-<p class="center">Nine figures, showing stages in the cell-division common to the onion root (<i lang="la" xml:lang="la">Allium cepa</i>, L.)</p>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_57">[57]</span></p>
-
-<h5 id="ORIGIN_OF_MULTICELLULAR_PLANTS">ORIGIN OF MULTICELLULAR PLANTS</h5>
-
-<p>All multicellular plants are built up by the repeated cell
-division of one original cell. If the cells formed are similar in
-structure and function, they form a tissue. In multicellular
-plants many different kinds of tissues will be formed as a result
-of cell division, since there are many different functions to be
-performed by such an organism. When several of these tissues
-become associated and their functions are correlated, they form
-an organ. The association of several organs in one form makes
-an organism. The oak-tree is an organism. It is made up of
-organs known as flowers, leaves, stems, roots, etc. Each of
-these organs is in turn made up of several kinds of tissue. In
-some cases it is difficult to designate a single function to an
-aggregation of cells (tissue). In fact, a tissue may perform
-different functions at different periods of its existence or it
-may perform two functions at one and the same time; as an
-example, stone cells, whose primary function is mechanical, in
-many cases function as storage tissue. The cells forming the
-tissues of the plant, in fact, show great adaptability in regard
-to the function which they perform. Nevertheless there is a
-predominating function which all tissues perform, and the
-structure of the cells forming such tissues is so uniform that it
-is possible to classify them.</p>
-
-<p>The functional classification of tissues is chosen for the
-purpose of demonstrating the adaptation of cell structure to
-cell function. If the cells performing a similar function in the
-different plants were identical in number, distribution, form,
-color, size, structure, and cell contents, there would not be a
-science of histology upon which the art of microscopic pharmacognosy
-is based. It may be said, however, with certainty,
-that the cells forming certain of the tissues of any given species
-of plant will differ in a recognizable degree from cells performing
-a similar function in other species of plants. Often a tissue
-is present in one plant but absent in another. For example,
-many aquatic plants are devoid of mechanical fibrous cells.
-The barks of certain plants have characteristic stone cells, while
-in many other barks no stone cells occur. Many leaves have
-characteristic trichomes; others are free from trichomes, etc.<span class="pagenum" id="Page_58">[58]</span>
-Yet all cells performing a given function will structurally resemble
-each other. In the present work the nucleus and other
-parts of the living protoplast will not be considered, for the
-reason that these parts are not in a condition suitable for study,
-because most drugs come to market in a dried condition, a condition
-which eliminates the possibility of studying the protoplast.
-The general structure of the cells forming the different
-tissues will first be considered, then their variation, as seen in
-different plants, and finally their functions.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_59">[59]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_II">CHAPTER II<br />
-<span class="fs80">THE EPIDERMIS AND PERIDERM</span></h3>
-</div>
-
-<p>The epidermis and its modifications, the hypodermis and
-the periderm, form the dermal or protective outer layer or layers
-of the plant.</p>
-
-<p>The epidermis of most leaves, stems of herbs, seeds, fruits,
-floral organs, and young woody stems consists of a single layer
-of cells which form an impervious outer covering, with the
-exception of the stoma.</p>
-
-<h4 id="LEAF_EPIDERMIS">LEAF EPIDERMIS</h4>
-
-<p>The cells of the <span class="bold">epidermis</span> vary in size, in thickness of the
-side and end walls, in form, in arrangement, in character of
-outgrowths, in the nature of the surface deposits, in the character
-of wall&mdash;whether smooth or rough&mdash;and in size.</p>
-
-<p>In cross-sections of the leaf the character of both the side
-and end walls is easily studied.</p>
-
-<p>In surface sections&mdash;the view most frequently seen in powders&mdash;the
-side walls are more conspicuous than the end wall
-(Plates 2 and 3). This is so because the light is considerably retarded
-in passing through the entire length of the side walls,
-while the light is retarded only slightly in passing through the
-end wall. The light in this case passes through the width
-(thickness) of the wall only. The outer walls of epidermal cells
-are characteristic only when they are striated, rough, pitted,
-colored, etc. In the majority of leaves the outer wall of the
-epidermal cells is not diagnostic in powders, or in surface
-sections.</p>
-
-<p>The thickness of the end and side walls of epidermal cells
-differs greatly in different plants.</p>
-
-<p>As a rule, leaves of aquatic and shade-loving plants, as well
-as the leaves of most herbs have thinner walled epidermal cells
-than have the leaves of plants growing in soil under normal
-conditions, or than have the leaves of shrubs and trees.</p>
-
-<p><span class="pagenum" id="Page_60">[60]</span></p>
-
-<div class="figcenter illowp51" id="plate2" style="max-width: 43.3125em;">
-  <img class="w100 p1" src="images/plate2.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 2</span><br />
-<span class="smcap">Leaf Epidermis</span><br />
-
-<div class="blockquotc">
-<p class="noindent">1. Uva-ursi (<i lang="la" xml:lang="la">Arctostaphylos uva-ursi</i>, [L.] Spring).<br />
-2. Boldus (<i lang="la" xml:lang="la">Peumus boldus</i>, Molina).<br />
-3. Catnip (<i lang="la" xml:lang="la">Nepeta cataria</i>, L.).<br />
-4. Digitalis (<i lang="la" xml:lang="la">Digitalis purpurea</i>, L.).<br />
-4-A. Origin of hair.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_61">[61]</span></p>
-
-<div class="figcenter illowp59" id="plate3" style="max-width: 49.25em;">
-  <img class="w100 p1" src="images/plate3.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 3</span><br />
-<span class="smcap">Leaf Epidermis</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Upper striated epidermis of chirata leaf (<i lang="la" xml:lang="la">Swertia chirata</i>, [Roxb.] Ham.).<br />
-2. Green hellebore leaf (<i lang="la" xml:lang="la">Veratrum viride</i>, Ait.).<br />
-3. Boldus leaf (<i lang="la" xml:lang="la">Peumus boldus</i>, Molina).<br />
-4. Under epidermis of India senna (<i lang="la" xml:lang="la">Cassia angustifolia</i>, Vahl.).</p>
-    </div>
-  </div>
-</div>
-
-
-<p><span class="pagenum" id="Page_62">[62]</span></p>
-
-<p>The widest possible range of cell-wall thickness is therefore
-found in the medicinal leaves, because the medicinal leaves are
-collected from aquatic plants, herbs, shrubs, trees, etc.</p>
-
-<p>The outer wall is always thicker than the side walls. Even
-the side walls vary in thickness in some leaves, the wall next
-to the epidermis being thicker than the lower or innermost
-portion of the wall. Frequently the outermost part of the side
-walls is unequally thickened. This is the case in the beaded
-side walls characteristic of the epidermis of the leaves of laurus,
-myrcia, boldus, and capsicum seed, etc. The thickness of the
-side walls of the epidermal cells of most leaves varies in the
-different leaves.</p>
-
-<p>In most leaves there are five <ins class="corr" id="tn62" title="Transcriber’s Note—“typical forms of arrangement of epidermal calls” changed to “typical forms of arrangement of epidermal cells”.">typical forms of arrangement of epidermal cells</ins>:
-First, those over the veins which are elongated in the direction of
-the length of the leaf; and, secondly, those on other parts of the
-leaf which are usually several-sided and not elongated in any one
-direction. If the epidermis of the leaf has stoma, then there is a
-third type of arrangement of the epidermal cells around the stoma;
-fourthly, the cells surrounding the base of hairs; and fifthly,
-outgrowths of the epidermis, non-glandular and glandular hairs,
-etc.</p>
-
-<p>It should be borne in mind that in each species of plant the
-five types of arrangement are characteristic for the species.</p>
-
-<p>The character of the outer wall of the epidermal cells differs
-greatly in different plants. In most cases the wall is smooth;
-senna is an example of such leaves. In certain other leaves the
-wall is rough, the roughness being in the form of striations.
-In some cases the striations occur in a regular manner; belladonna
-leaf is typical of such leaves. In other instances the wall
-is striated in an irregular manner as shown in chirata epidermis.
-Very often an epidermis is rough, but the roughness is not due
-to striations. In these cases the epidermis is unevenly thickened,
-the thin places appearing as slight depressions, the thick places
-as slight elevations. Boldus has a rough, but not a striated
-surface.</p>
-
-<p><span class="bold">Surface deposits</span> are not of common occurrence in medicinal
-plants; waxy deposits occur on the stem of sumac, on a species<span class="pagenum" id="Page_63">[63]</span>
-of raspberry, on the fruit of bayberry, etc. Resinous deposits
-occur on the leaves and stems of grindelia species, and on yerba
-santa.</p>
-
-<p>In certain leaves there are two or three layers of cells beneath
-the epidermis that are similar in structure to the epidermal cells.
-These are called hypodermal cells, and they function in the
-same way as the epidermal cells.</p>
-
-<p>Hypodermal cells are very likely to occur on the margin of
-the leaf. Uva-ursi leaf has a structure typical of leaves with
-hypodermal marginal cells. Uva-ursi, like other leaves with
-hypodermal cells has a greater number of hypodermal cells
-at the leaf margin than at any other part of the leaf
-surface.</p>
-
-<p>The cutinized walls of epidermal cells are stained red with
-saffranin.</p>
-
-<h4 id="TESTA_EPIDERMIS">TESTA EPIDERMIS</h4>
-
-<p><span class="bold">Testa epidermal cells</span> form the epidermal layers of such
-seeds as lobelia, henbane, capsicum, paprika, larkspur, belladonna,
-scopola, etc.</p>
-
-<p>In surface view the end walls are thick and wavy in outline;
-frequently the line of union&mdash;middle lamella&mdash;of two cells is indicated
-by a dark or light line, while in others the wall between
-two cells appears as a single wall. The walls are porous or
-non-porous, and the color of the wall varies from yellow to
-brown, to colorless. These cells always occur in masses, composed
-partially of entire and partially of broken fragments.</p>
-
-<p>In lobelia seed (Plate 4, Fig. 2) the line of union of adjacent
-cell walls appears as a dark line. The walls are wavy in outline,
-of a yellowish-red color and not porous.</p>
-
-<p>In henbane seed (Plate 4, Fig. 3) the line of union between
-the cells is scarcely visible; the walls are decidedly wavy, more
-so than in lobelia, and no pits are visible.</p>
-
-<p>In capsicum seed (Plate 4, Fig. 1) the cells are very wavy
-and decidedly porous, the line of union between the cell walls
-being marked with irregular spaces and lines.</p>
-
-<p>In belladonna seed (Plate 5, Fig. 1) the walls between two
-adjacent cells are non-striated and non-porous, and extremely
-irregular in outline.</p>
-
-<p><span class="pagenum" id="Page_64">[64]</span></p>
-
-<div class="figcenter illowp57" id="plate4" style="max-width: 47.75em;">
-  <img class="w100 p1" src="images/plate4.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 4</span><br />
-<span class="smcap">Testa Epidermal Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Capsicum seed (<i lang="la" xml:lang="la">Capsicum frutescens</i>, L.).<br />
-2. Lobelia seed (<i lang="la" xml:lang="la">Lobelia inflata</i>, L.).<br />
-3. Henbane seed (<i lang="la" xml:lang="la">Hyoscyamus niger</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_65">[65]</span></p>
-
-<div class="figcenter illowp53" id="plate5" style="max-width: 44.875em;">
-  <img class="w100 p1" src="images/plate5.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 5</span><br />
-<span class="smcap">Testa Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Belladonna seed (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.).<br />
-2. Star-aniseed (<i lang="la" xml:lang="la">Illicium verum</i>, Hooker).<br />
-3. Stramonium seed (<i lang="la" xml:lang="la">Datura stramonium</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_66">[66]</span></p>
-
-<p>In star-anise seed (Plate 5, Fig. 2) the walls are irregularly
-thickened and wavy in outline.</p>
-
-<p>In stramonium seed (Plate 5, Fig. 3) the walls are very
-thick, wavy in outline, and striated.</p>
-
-<h4 id="PLANT_HAIRS">PLANT HAIRS (<span class="allsmcap">TRICHOMES</span>)</h4>
-
-<p>In histological work plant hairs are of great importance, as
-they offer a ready means of distinguishing and differentiating
-between plants, or parts of plants, when they occur in a broken
-or finely powdered condition. There is no other element in
-powdered drugs which is of so great a diagnostic value as the
-plant hair. The same plant will always have the same type
-of hair, the only noticeable variation being in the size. In
-microscopical drug analysis the presence of hairs is always noted,
-and in many cases the purity of the powder can be ascertained
-from the hairs. Botanists seem to have given little attention to
-the study of plant hairs. This accounts for the fact that information
-concerning them is very meagre in botanical literature,
-and, as far as the author can learn, no one has attempted to
-classify them. In systematic work, plant hairs could be used
-to great advantage in separating genera and even species.
-Hairs are, of course, a factor now in systematic work. The
-lack of hairs is indicated by the term glabrous. Their presence
-is indicated by such terms as hispid, villous, etc. In certain
-cases the term indicates position of the hair as ciliate when the
-hair is marginal. When hairs influence the color of the leaf,
-such terms as cinerous and canescent are used. In all the cases
-cited no mention is made of the real nature of the hair.</p>
-
-<p>In systematic work, as in pharmacognosy, we must work
-with dried material, and it is only those hairs which retain
-their form under such conditions which are of classification
-value.</p>
-
-<p>Hairs are the most common outgrowths of the epidermal
-cells. They are classified as glandular or non-glandular, according
-to their structure and function. The glandular hairs will
-be considered under synthetic tissue.</p>
-
-<p>Each group is again subdivided into a number of secondary
-groups, depending upon the number of cells present, their form,<span class="pagenum" id="Page_67">[67]</span>
-their arrangement, their size, their color, the character of their
-walls, whether rough or smooth, whether branched or non-branched,
-whether curved, twisted, straight, or twisted and
-straight, whether pointed, blunt, or forked.</p>
-
-<h4 id="FORMS_OF_HAIRS">FORMS OF HAIRS</h4>
-
-<h5 id="PAPILLAE">PAPILLÆ</h5>
-
-<p><span class="bold">Papillæ</span> are epidermal cells which are extended outward in
-the form of small tubular outgrowths.</p>
-
-<p>Papillæ occur on the following parts of the plant: flower-petals,
-stigmas, styles, leaves, stems, seeds, and fruits. Papillæ
-occur on only a few of the medicinal leaves.</p>
-
-<p>The under surface of both Truxillo (Plate 6, Fig. 3) and
-Huanuca coca have very small papillæ. The outermost wall of
-these papillæ are much thicker than the side walls. The papillæ
-of klip buchu (Plate 6, Fig. 4), an adulterant of true buchu, has
-large thick-walled papillæ.</p>
-
-<p>The velvety appearance of most flower-petals (Plate 6,
-Figs. 2 and 5) is due to the presence of papillæ. The papillæ
-of flower-petals are very variable. In calendula flowers (Plate
-6, Fig. 1) they are small, yellowish in color, and the outer wall
-is marked with parallel striations which appear as small teeth
-in cross-section. The ray petal papillæ of anthemis consist of
-rather large, broad, blunt papillæ with slightly striated walls.
-The papillæ of the ray petals of the white daisy consist of papillæ
-which have medium sized, cone-shaped papillæ with finely striated
-walls. The papillæ of the flower stigma vary greatly in different
-flowers. In some cases two or more types of papillæ occur,
-but even in these cases the papillæ are characteristic of the
-species.</p>
-
-<p>The papillæ differ greatly in the case of the flowers of the
-compositæ, where two types of flowers are normally present&mdash;namely,
-the ray flowers and the disk flowers.</p>
-
-<p>In all cases observed the papillæ of the stigma of the ray
-flowers are always smaller than the papillæ of the stigma of the
-disk flowers. It would appear from extended observation that
-the papillæ of the ray flower stigma are being gradually aborted.
-The papillæ of the style are always different from the papillæ
-of the stigma. The style papillæ are always smaller, and they
-are of a different form.</p>
-
-<p><span class="pagenum" id="Page_68">[68]</span></p>
-
-<div class="figcenter illowp79" id="plate6" style="max-width: 65.875em;">
-  <img class="w100 p1" src="images/plate6.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 6</span><br />
-<span class="smcap">Papillæ</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Calendula flowers (<i lang="la" xml:lang="la">Calendula officinalis</i>, L.).<br />
-2. White daisy ray flower (<i lang="la" xml:lang="la">Chrysanthemum leucanthemum</i>, L.).<br />
-3. Coca leaf (<i lang="la" xml:lang="la">Erythroxylon coca</i>, Lamarck).<br />
-4. Klip buchu.<br />
-5. Anthemis ray petal (<i lang="la" xml:lang="la">Anthemis nobilis</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_69">[69]</span></p>
-
-<h5 id="UNICELLULAR_NON-GLANDULAR_HAIRS">UNICELLULAR NON-GLANDULAR HAIRS</h5>
-
-<p><span class="bold">True plant hairs</span> are tubular outgrowths of the epidermal
-cell, the length of these outgrowths being several times the
-width of the hair.</p>
-
-<p>The unicellular hairs are common to many plants. The two
-groups of non-glandular unicellular hairs are, first, the solitary;
-and secondly, the clustered hairs.</p>
-
-<p><span class="bold">Solitary unicellular hairs</span> occur on the leaves of chestnut,
-yerba santa, lobelia, cannabis indica, the fruit of anise, and
-the stem of allspice, senna, and cowage.</p>
-
-<p>Chestnut hairs (Plate 7, Fig. 1) have smooth yellowish-colored
-walls, and the cell cavity contains reddish-brown tannin. These
-hairs occur solitary or clustered; the clustered hairs normally
-occur on the leaf, but in powdering the drug, individual hairs of
-the cluster become separated or solitary.</p>
-
-<p>Yerba santa hairs (Plate 7, Fig. 4) are twisted, the lumen or
-cell cavity is very small, and the walls, which are very thick,
-are grayish-white.</p>
-
-<p>Lobelia hairs (Plate 7, Fig. 5) are very large. The walls
-are grayish-white, and the outer surface extends in the form
-of small elevations which make the hair very rough. The hair
-tapers gradually to a solid point.</p>
-
-<p>Cannabis indica hairs (Plate 7, Fig. 6) are curved. The
-apex tapers to a point and the base is broad, and it frequently
-contains deposits of calcium carbonate. The walls are grayish-white
-in appearance, and rough. The roughness increases
-toward the apex.</p>
-
-<p>The hairs of anise (Plate 7, Fig. 7) are mostly curved; the
-walls are thick, yellowish-white, and the outer surface is rough;
-this is due to the numerous slight centrifugal projections of the
-outer wall.</p>
-
-<p>Allspice stem hairs (Plate 7, Fig. 2) have smooth walls.
-The cell cavity is reddish-brown. The hair is curved.</p>
-
-<p>The hair of senna (Plate 7, Fig. 10) is light greenish-yellow
-with rough papillose walls. The hair is usually curved and
-tapering, and it does not have any characteristic cell contents.</p>
-
-<p><span class="pagenum" id="Page_70">[70]</span></p>
-
-<div class="figcenter illowp56" id="plate7" style="max-width: 46.75em;">
-  <img class="w100 p1" src="images/plate7.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 7</span><br />
-<span class="smcap">Unicellular Solitary Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Chestnut leaf (<i lang="la" xml:lang="la">Castanea dentata</i>, [Marsh] Borkh).<br />
-2. Allspice stems (<i lang="la" xml:lang="la">Pimento, officinalis</i>, Lindl.).<br />
-3. Cowage.<br />
-4. Yerba santa (<i lang="la" xml:lang="la">Eriodictyon californicum</i>, [H. and A.] Greene).<br />
-5. Lobelia (<i lang="la" xml:lang="la">Lobelia inflata</i>, L.).<br />
-6. Cannabis indica (<i lang="la" xml:lang="la">Cannabis saliva</i>, L.).<br />
-7. Anise fruit (<i lang="la" xml:lang="la">Pimpinella anisum</i>, L.).<br />
-8. Hesperis matronalis (<i lang="la" xml:lang="la">Hesperis matronalis</i>, L.).<br />
-9. Galphimia glauca (<i lang="la" xml:lang="la">Galphimia glauca</i>, Cav.).<br />
-10. Senna (<i lang="la" xml:lang="la">Cassia angustifolia</i>, Vahl.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_71">[71]</span></p>
-
-<div class="figcenter illowp56" id="plate8" style="max-width: 47.3125em;">
-  <img class="w100 p1" src="images/plate8.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 8</span><br />
-<span class="smcap">Clustered Unicellular Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. and 2. European oak (<i lang="la" xml:lang="la">Quercus infectoria</i>, Olivier).<br />
-3. Kamala (<i lang="la" xml:lang="la">Mallotus philippinensis</i>, [Lam.] [Muell.] Arg.).<br />
-4. Witch-hazel leaf (<i lang="la" xml:lang="la">Hamamelis virginiana</i>, L.).<br />
-5. Althea leaf (<i lang="la" xml:lang="la">Althæa officinalis</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_72">[72]</span></p>
-
-<p>Cowage hairs (Plate 7, Fig. 3) are lance-shaped, and they
-terminate in a sharp point. The outer wall contains numerous
-recurved teeth-like projections. The cell cavity is filled with
-a reddish-brown contents which are somewhat fissured.</p>
-
-<p><span class="bold">Clustered unicellular hairs</span> occur on the leaves of chestnut,
-witch-hazel, althea, European oak, etc. In European oak (Plate
-8, Figs. 1 and 2) clusters of two and three hairs occur. The
-walls are yellowish-white, smooth, and the tip of the hair is solid.</p>
-
-<p>In kamala (Plate 8, Fig. 3) clusters of seven or more hairs
-occur; the walls are yellowish, and the cell cavity is reddish-brown.
-In witch-hazel leaf (Plate 8, Fig. 4) clusters of a variable
-number of hairs occur. The hairs, which are of various lengths,
-have yellowish-white, thick, smooth walls, and reddish cell
-contents.</p>
-
-<p>In althea leaf (Plate 8, Fig. 5) the hairs are nearly straight
-and the walls are smooth. The basal portions of the hair are
-strongly pitted.</p>
-
-<p><span class="bold">Branched solitary unicellular hairs</span> occur on the leaves of
-hesperis matronalis (Plate 7, Fig. 8), and on galphimia glauca
-(Plate 7, Fig. 9).</p>
-
-<p>The hair of hesperis matronalis has smooth walls, and the
-two branches grow out nearly parallel to the leaf surface.</p>
-
-<p>The hair of galphimia glauca has rough walls, and the two
-branches grow upward in a bifurcating manner.</p>
-
-<h5 id="MULTICELLULAR_HAIRS">MULTICELLULAR HAIRS</h5>
-
-<p><span class="bold">Multicellular</span> hairs are divided into the uniseriate and the
-multiseriate hairs. Both of these groups are divided into the
-branched and the non-branched hairs, as follows:</p>
-
-<p>1. <span class="bold">Uniseriate</span>.<br />
-<span class="pad2">(<em>A</em>)</span> <span class="bold">Non-branched.</span><br />
-<span class="pad2">(<em>B</em>)</span> <span class="bold">Branched.</span></p>
-
-<p class="p0">2. <span class="bold">Multiseriate.</span><br />
-<span class="pad2">(<em>A</em>)</span> <span class="bold">Non-branched.</span><br />
-<span class="pad2">(<em>B</em>)</span> <span class="bold">Branched.</span></p>
-
-<p><span class="bold">Multicellular uniseriate non-branched hairs</span> occur on the
-leaves of digitalis, Western and Eastern skullcap, peppermint,
-thyme, yarrow, arnica flowers, and sumac fruit.</p>
-
-<p><span class="pagenum" id="Page_73">[73]</span></p>
-
-<div class="figcenter illowp53" id="plate9" style="max-width: 44.8125em;">
-  <img class="w100 p1" src="images/plate9.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 9</span><br />
-<span class="smcap">Multicellular Uniseriate Non-Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Digitalis leaf (<i lang="la" xml:lang="la">Digitalis purpurea</i>, L.).<br />
-2. Arnica flower (<i lang="la" xml:lang="la">Arnica montana</i>, L.).<br />
-3. Western skullcap plant (<i lang="la" xml:lang="la">Scutellaria canescens</i>, Nutt.).<br />
-4. Eastern skullcap plant (<i lang="la" xml:lang="la">Scutellaria lateriflora</i>, L.).<br />
-5. Peppermint leaf (<i lang="la" xml:lang="la">Mentha piperita</i>, L.).<br />
-6. Thyme leaf (<i lang="la" xml:lang="la">Thymus vulgaris</i>, L.).<br />
-7. Yarrow flowers (<i lang="la" xml:lang="la">Achillea millefolium</i>, L.).<br />
-8. Wormwood leaf (<i lang="la" xml:lang="la">Artemisia absinthium</i>, L.).<br />
-9. Sumac fruit (<i lang="la" xml:lang="la">Rhus glabra</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_74">[74]</span></p>
-
-<p>Digitalis hairs (Plate 9, Fig. 1) are made up of a varying
-number of uniseriate-arranged cells of unequal length, frequently
-placed at right angles to the cells above and below; the walls
-are of a whitish color, and are rough or smooth.</p>
-
-<p>Eastern skullcap (Plate 9, Fig. 4) has hairs with not more
-than four cells; these hairs are curved, and the walls are whitish,
-sometimes smooth, but usually rough. In Western skullcap
-(Plate 9, Fig. 3) the hairs have sometimes as many as seven
-cells. The walls are white and rough, and the individual cells
-of the hair are much larger than are the cells of the hairs of
-true skullcap.</p>
-
-<p>Peppermint (Plate 9, Fig. 5) has from one to eight cells.
-The hair is curved, and the walls are very rough.</p>
-
-<p>Thyme (Plate 9, Fig. 6) has short, thick, rough-walled
-trichomes, the terminal cell usually being bent at nearly right
-angles to the other cells.</p>
-
-<p>Yarrow hairs (Plate 9, Fig. 7) have a variable number of
-cells. In all the hairs the basal cells are short and broad, while
-the terminal cell is greatly elongated.</p>
-
-<p>Arnica hairs (one form, Plate 9, Fig. 2) have frequently as
-many as four cells, the terminal cell being longer than the basal
-cells. The walls are white and smooth.</p>
-
-<p>Sumac-fruit hairs (Plate 9, Fig. 9) have spindle-shaped,
-reddish-colored hairs.</p>
-
-<p><span class="bold">Multicellular multiseriate non-branched hairs</span> occur on
-cumin fruit and on the tubular part of the corolla of calendula.</p>
-
-<p>The hairs on cumin fruit vary considerably in size. All the
-hairs are spreading at the base and blunt or rounded at the apex.
-The cells forming the hair are narrow and the walls are thick.
-Three differently sized hairs are shown in Plate 10, Fig. 1.</p>
-
-<p>The hairs of the base of the ligulate petals of calendula
-(Plate 10, Fig. 2) are biseriate. The hairs are very long and
-the walls are very thin.</p>
-
-<p><span class="bold">Multicellular uniseriate branched hairs</span> occur on the leaves
-of dittany of Crete, mullen, and on the calyx of lavender flowers.</p>
-
-<p>The dittany of Crete (Plate 11, Fig. 3) hair is smooth-walled,
-and the branches are alternate.</p>
-
-<p>In mullen (Plate 11, Fig. 1) the hairs have whorled branches,
-the walls are smooth, and the cell cavity usually contains air.</p>
-
-<p><span class="pagenum" id="Page_75">[75]</span></p>
-
-<div class="figcenter illowp52" id="plate10" style="max-width: 43.875em;">
-  <img class="w100 p1" src="images/plate10.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 10</span><br />
-<span class="smcap">Multicellular Multiseriate Non-Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Cumin (<i lang="la" xml:lang="la">Cuminum cyminum</i>, L.).<br />
-2. Marigold (<i lang="la" xml:lang="la">Calendula officinalis</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_76">[76]</span></p>
-
-<div class="figcenter illowp64" id="plate11" style="max-width: 53.5em;">
-  <img class="w100 p1" src="images/plate11.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 11</span><br />
-<span class="smcap">Multicellular Uniseriate Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Mullen leaf (<i lang="la" xml:lang="la">Verbascum thapsus</i>, L.).<br />
-2. Lavender flowers (<i lang="la" xml:lang="la">Lavandula vera</i>, D. C.).<br />
-3. Dittany of Crete (<i lang="la" xml:lang="la">Origanum dictamnus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_77">[77]</span></p>
-
-<p>The lavender hairs (Plate 11, Fig. 2) have mostly opposite
-branches, and the walls are rough. Thus the multicellular
-branched hairs may be divided into subgroups which have
-alternate, opposite, whorled, or in certain hairs irregularly arranged
-branches. Each class may be again subdivided according
-to color, character of cell termination, etc., as cited at the
-beginning of the chapter.</p>
-
-<p>Occasionally multicellular hairs assume the form of a shield
-(Plate 12, Fig. 1); in such cases the hair is termed peltate, as in
-the non-glandular multicellular hair of shepherdia canadensis.</p>
-
-<p>Hairs grow out from the surface of the epidermis in a perpendicular,
-a parallel, or in an oblique direction. Hairs which
-grow parallel or oblique to the surface are usually curved, and
-the outer curved part of the wall is usually thicker than the
-inner curved wall.</p>
-
-<p>The mature hairs of some plants consist of dead cells. In
-other plants the cells forming the hair are living. When dried,
-those hairs, which were dead before drying, contain air; while
-those hairs which were living before drying, show great variation
-in color and in the nature of the cell contents. The contents
-are either organic or inorganic. The commonest organic constituent
-is dried protoplasm. In cannabis indica are deposits
-of calcium carbonate.</p>
-
-<p><span class="bold">Multicellular multiseriate branched hairs</span> are the ultimate
-division of the pappus of erigeron, aromatic goldenrod, arnica,
-grindelia, boneset, and life-everlasting.</p>
-
-<p>The hairs of erigeron (Plate 13, Figs. 1 and 2) are slender;
-the walls are porous. Each hair terminates in two cells, which
-are greatly extended and sharp-pointed; the branches from the
-basal part of the hairs (Plate 13, Fig. 1) are of about the same
-length as the apical branches.</p>
-
-<p>The hairs of aromatic goldenrod (Plate 13, Figs. 3 and 4) are
-larger than those of erigeron; the diameter is greater and the
-walls are non-porous. The apex of the hair terminates in a
-group of about four cells of unequal length, which are sharp-pointed.
-The branches of the basal cells (Plate 13, Fig. 3) are
-similar to the branches of the apical cells.</p>
-
-<p>The hairs of arnica (Plate 14, Figs. 1 and 2) have thick,
-strongly porous walls; the branches terminate in sharp points.
-The apex of the hair terminates in a single cell. The basal
-branches (Plate 14, Fig. 2) are much longer than special
-branches.</p>
-
-<p><span class="pagenum" id="Page_78">[78]</span></p>
-
-<div class="figcenter illowp61" id="plate12" style="max-width: 50.875em;">
-  <img class="w100 p1" src="images/plate12.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 12</span><br />
-<span class="smcap">Non-Glandular Multicellular Hairs</span><br />
-<i lang="la" xml:lang="la">Shepherdia canadensis</i>, [L.] Nutt.
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_79">[79]</span></p>
-
-<div class="figcenter illowp47" id="plate13" style="max-width: 134.0625em;">
-  <img class="w100 p1" src="images/plate13.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 13</span><br />
-<span class="smcap">Multicellular Multiseriate Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Basal hairs of erigeron (<i lang="la" xml:lang="la">Erigeron canadensis</i>, L.).<br />
-2. Apical hairs of erigeron (<i lang="la" xml:lang="la">Erigeron canadensis</i>, L.).<br />
-3. Basal hairs of aromatic goldenrod (<i lang="la" xml:lang="la">Solidago odora</i>, Ait.).<br />
-4. Apical hairs of aromatic goldenrod (<i lang="la" xml:lang="la">Solidago odora</i>, Ait.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_80">[80]</span></p>
-
-<p>The hair of grindelia (Plate 14, Figs. 3 and 4) has very thick
-walls with numerous elongated pores. The apex of the hair
-terminates in a cluster of cells with short, free, sharp-pointed
-ends. The basal branches (Plate 14, Fig. 4) are longer than
-the apical branches.</p>
-
-<p>Boneset hair (Plate 15, Figs. 1 and 2) has non-porous walls.
-The apex of the hair terminates in two blunt-pointed cells.
-The terminal wall is thicker than the side wall. Some of the
-branches lower down terminate in cells with very thick or solid
-points. The basal branches (Plate 15, Fig. 1) are longer, but
-the cells are narrower and more strongly tapering than are the
-branches of the apical part of the hair.</p>
-
-<p>Life-everlasting (Plate 15, Figs. 3 and 4) has uniformly
-thickened but non-porous walls. The hair terminates in two
-blunt-pointed, greatly elongated cells.</p>
-
-<p>The basal branches (Plate 15, Fig. 4) are narrower, slightly
-tapering, and the base of the branches frequently curve downward.</p>
-
-<p>The cell cavities of these hairs are filled with air.</p>
-
-<p>The walls of hairs are composed of cutin, of lignin, and
-of cellulose.</p>
-
-<h4 id="PERIDERM">PERIDERM</h4>
-
-<p>The <span class="bold">periderm</span> is the outer protective covering of the stems
-and roots of mature shrubs and trees. The periderm replaces
-the epidermis. The periderm may be composed of cork cells,
-stone cell-cork, or a mixture of cork, parenchyma, fibres, stone
-cells, etc.</p>
-
-<h4 id="CORK_PERIDERM">CORK PERIDERM</h4>
-
-<p>The typical periderm is made up of <span class="bold">cork cells</span>. Cork cells
-vary in appearance, according to the part of the cell viewed.</p>
-
-<p><span class="pagenum" id="Page_81">[81]</span></p>
-
-<div class="figcenter illowp48" id="plate14" style="max-width: 40em;">
-  <img class="w100 p1" src="images/plate14.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 14</span><br />
-<span class="smcap">Multicellular Multiseriate Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Apical hairs arnica (<i lang="la" xml:lang="la">Arnica montana</i>, L.).<br />
-2. Basal hairs arnica (<i lang="la" xml:lang="la">Arnica montana</i>, L.).<br />
-3. Apical hairs grindelia (<i lang="la" xml:lang="la">Grindelia squarrosa</i>, [Pursh] Dunal).<br />
-4. Basal hairs grindelia (<i lang="la" xml:lang="la">Grindelia squarrosa</i>, [Pursh] Dunal).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_82">[82]</span></p>
-
-<div class="figcenter illowp53" id="plate15" style="max-width: 44.25em;">
-  <img class="w100 p1" src="images/plate15.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 15</span><br />
-<span class="smcap">Multicellular Multiseriate Branched Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Apical hairs boneset (<i lang="la" xml:lang="la">Eupatorium perfoliatum</i>, L.).<br />
-2. Basal hairs boneset (<i lang="la" xml:lang="la">Eupatorium perfoliatum</i>, L.).<br />
-3. Apical hairs life-everlasting (<i lang="la" xml:lang="la">Gnaphalium obtusifolium</i>, L.).<br />
-4. Basal hairs life-everlasting (<i lang="la" xml:lang="la">Gnaphalium obtusifolium</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_83">[83]</span></p>
-
-<p>On surface view (Plate 16, Fig. A) the cork cells are angled
-in outline and are made up of from four to seven side walls;
-five- and six-sided cells are more common than the four-and
-seven-sided cells. Surface sections of cork cells show their
-length and width. These side walls usually appear nearly white,
-while the end wall, particularly of the outermost cork cells,
-usually appears brown or reddish-brown, or in some cases nearly
-black.</p>
-
-<p>Cork cells on cross-section are rectangular in form, and they
-are arranged in superimposed rows, the number of rows being
-gradually increased as the plant grows older. Such an increase
-in the number of rows of cork cells is shown in the cross-section
-of cascara sagrada (Plate 16, Fig. C).</p>
-
-<p>Cork cells fit together so closely that there is no intercellular
-spaces between the cells. In this case two rows of cork cells
-occupy no greater space than the solitary row of cork cells
-immediately over and external to them. As a rule, the outermost
-layers of cork cells have a narrower radial diameter than
-the cork cells of the underlying layers. This is due to the fact
-that these outer cells are stretched as the stem increases in
-diameter. This view shows the height of cork cells, but not
-always the length, which will, of course, vary according to the
-part of the cell cut across. In a section a few millimeters in
-diameter, however, all the variations in size may be observed.
-The color of the walls is nearly white.</p>
-
-<p>The cavity may contain tannin or other substances. When
-tannin is present, the cavity is of a brownish or brownish-red
-color, or it may be nearly black. Most barks appear devoid of
-any colored or colorless cell contents.</p>
-
-<p>The radial section (Plate 16, Fig. B) of cork cells shows the
-height of the cells and the width of the cells at the point cut
-across. Some cells will be cut across their longest diameter, while
-others will be cut across their shortest diameter. Cork cells are,
-therefore, smaller in radial section than they are in cross-section.
-The color of the walls is white, and the color and nature of the
-cell contents vary for the same reasons that they vary in
-cross-sections.</p>
-
-<p>The number of layers of cork cells occurring in cross- and
-radial-sections varies according to the age of the plant, to the type
-of plant, and to the conditions under which the plant is growing.</p>
-
-<p>The number of layers of cork cells is not of diagnostic importance,
-nor is the surface view of cork cells diagnostic except
-in certain isolated cases.</p>
-
-<p><span class="pagenum" id="Page_84">[84]</span></p>
-
-<div class="figcenter illowp50" id="plate16" style="max-width: 42.125em;">
-  <img class="w100 p1" src="images/plate16.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 16</span><br />
-<span class="smcap">Periderm of Cascara Sagrada</span> (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D.C.)
-
-<div class="blockquotc">
-<p><em>A.</em>  1, Outline of cork cells; 2, Line of contact of adjoining cork cells.<br />
-<span class="pad1"><em>B.</em></span>  Radial longitudinal section of cascara sagrada. 1, Cork cells; 2, Phellogen; 3, Forming parenchyma cells; 4, Cortical parenchyma cells.<br />
-<span class="pad1"><em>C.</em></span> Cross-section of cascara sagrada. 1, Cork cells; 2, Phellogen; 3, Forming parenchyma cells; 4, Cortical parenchyma cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_85">[85]</span></p>
-
-<p>The presence or absence of cork or epidermal tissue in powders
-must always be noted. The presence of cork enables one to
-distinguish Spanish from Russian licorice. In like manner, the
-presence of epidermis enables one to distinguish the pharmacopœial
-from the unofficial peeled calamus. The absence of
-epidermis in Jamaica ginger is one of the means by which this
-variety is distinguished from the other varieties of ginger, etc.</p>
-
-<p>In canella alba the periderm is replaced by stone cell-cork.
-That is, the cells forming the periderm are of a typical cork
-shape, but the walls are lignified, unequally thickened, and
-the inner or thicker walls are strongly porous, and the walls
-are of a yellowish color. Stone cell-cork forms the periderm
-of clove bark also, but the cells are narrower and longer, and
-the inner wall is not so thick or porous as is the case in canella
-alba bark.</p>
-
-<h4 id="STONE_CELL_PERIDERM">STONE CELL PERIDERM</h4>
-
-<p>In canella alba (Plate 17, Fig. B) cork periderm is frequently
-replaced by stone cells, particularly in the older barks. These
-stone cells form the periderm because they replace the cork
-periderm, which fissures and scales off as the root increases
-in diameter.</p>
-
-<p>The side and end walls of cork cells are of nearly uniform
-diameter. Exceptions occur, but they are not common. In
-buchu stem (Plate 101, Fig. 3), the cork cells have thick outer
-walls, but thin sides and inner walls. The cell cavity contains
-reddish-brown deposits of tannin.</p>
-
-<h4 id="PARENCHYMA_AND_STONE_CELL_PERIDERM">PARENCHYMA AND STONE CELL PERIDERM</h4>
-
-<p>As the trees and shrubs increase in diameter, cracks or fissures
-occur in the periderm, or corky layer. In such cases the
-phellogen cells divide and redivide in such manner as to cut
-off a portion of the parenchyma cells, stone cells, and fibres of
-the cortex which is inside of and below the fissure. All the
-parenchyma cells, etc., exterior to the newly formed cork cells
-soon lose their living-cell contents, since their food-supply is
-cut off by the impervious walls of the cork cells. In time they
-are forced outward by the developing cork cells until they
-partially or completely fill the break in the periderm. In white
-oak bark (Plate 18), as in other barks, a large part of the periderm
-is composed of dead and discolored cortical cells.</p>
-
-<p><span class="pagenum" id="Page_86">[86]</span></p>
-
-<div class="figcenter illowp55" id="plate17" style="max-width: 46.3125em;">
-  <img class="w100 p1" src="images/plate17.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 17</span>
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Cross-section of Mandrake Rhizome (<i lang="la" xml:lang="la">Podophyllum peltatum</i>, L.).<br />
-<span class="pad1">1. Epidermis.</span><br />
-<span class="pad1">2. Phellogen.</span><br />
-<span class="pad1">3. Cortical parenchyma.</span><br />
-<em>B.</em> Stone cell periderm of white cinnamon (<i lang="la" xml:lang="la">Canella alba</i>, Murr.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_87">[87]</span></p>
-
-<div class="figcenter illowp100" id="plate18" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate18.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 18</span><br />
-<span class="smcap">Periderm of White Oak</span> (<i lang="la" xml:lang="la">Quercus alba</i>, L.)
-
-<div class="blockquotc">
-<p>1. Outer layer of cork cells. 2. Cortical parenchyma cells. 3. Stone cells. 4. Phellogen. 5. Cortical parenchyma cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_88">[88]</span></p>
-
-<h5>ORIGIN OF CORK CELLS</h5>
-
-<p>The cork cells are formed by the meristimatic phellogen
-cells, which originate from cortical parenchyma. These cells
-divide into two cells, the outer changing into a cork cell, while
-the inner cell remains meristimatic. In other instances the
-outer cell remains meristimatic, while the inner cell changes
-into a cortical parenchyma cell. The development of a cortical
-parenchyma cell from a divided phellogen cell is shown in Plate
-101, Fig. 6. Both the primary and secondary cork cells originate
-from the phellogen or cork cambrium layer. Cork cells do not
-contain living-cell contents; in fact, in the majority of medicinal
-barks the cork cells contain only air.</p>
-
-<p>The walls of typical cork cells are composed, at least in part,
-of suberin, a substance which is impervious to water and gases.
-In certain cases layers of cellulose, lignin, and suberin have been
-identified. Suberin, however, is present in all cork cells, and
-in some cases all of the walls of cork cells are composed of suberin.</p>
-
-<p>Suberized cork cells are colored yellow with strong sodium
-hydroxide solutions and by chlorzinciodide.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_89">[89]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_III">CHAPTER III<br />
-<span class="fs80">MECHANICAL TISSUES</span></h3>
-</div>
-
-<p>The <span class="bold">mechanical tissues</span> of the plant form the framework
-around which the plant body is built up. These tissues are
-constructed and placed in such a manner in the different organs
-of the plant as to meet the mechanical needs of the organ. Many
-underground stems and roots which are subjected to radial pressure
-have the hypodermal and endodermal cells arranged in the
-form of a non-compressible cylinder. Such an arrangement is
-seen in sarsaparilla root (Plate 38, Fig. 4). The mechanical
-tissue of the stem is arranged in the form of solid or hollow
-columns in order to sustain the enormous weight of the branches.
-In roots the mechanical tissue is combined in ropelike strands,
-thereby effectively resisting pulling stresses. The epidermis of
-leaves subjected to the tearing force of the wind has epidermal
-cells with greatly thickened walls, particularly at the margin of
-the leaf. The epidermal cells of most seeds have very thick
-and lignified cell walls, which effectively resist crushing forces.</p>
-
-<p>The cells forming mechanical tissues are: bast fibres, wood
-fibres, collenchyma cells, stone cells, testa epidermal cells, and
-hypodermal and endodermal cells of certain plants. The walls
-of the cells forming mechanical tissues are thick and lignified,
-with the exception of the collenchyma cells and a few of the
-fibres. Lignified cells are as resistive to pulling and other
-stresses as similar sized fragments of steel. The hardness of
-their wall and their resistance to crushing explain the fact that
-they usually retain their form in powdered drugs and foods.</p>
-
-<h4 id="BAST_FIBRES">BAST FIBRES</h4>
-
-<p>One of the most important characters to be kept in mind in
-studying bast fibres is the structure of the wall. In fact, the
-author’s classification of bast fibres is based largely on wall<span class="pagenum" id="Page_90">[90]</span>
-structure. Such a classification is logical and accurate, because
-it is based upon permanent characters. Another character used
-in classifying bast fibres is the nature of the cell, whether branched
-or non-branched. In fact, this latter character is used to separate
-all bast fibres into two fundamental groups&mdash;namely, branched
-bast fibres and non-branched bast fibres. The third important
-character utilized in classifying fibres is the presence or absence
-of crystals.</p>
-
-<p>Bast fibres are classified as follows:<br />
-<span class="pad2">1. <span class="bold">Crystal bearing.</span></span><br />
-<span class="pad2">2. <span class="bold">Non-crystal bearing.</span></span></p>
-
-<p>The crystal-bearing fibres are divided into two classes:<br />
-<span class="pad2">1. <span class="bold">Of leaves.</span></span><br />
-<span class="pad2">2. <span class="bold">Of barks.</span></span></p>
-
-<p>The non-crystal bearing are divided into:<br />
-<span class="pad2">1. <span class="bold">Branched.</span></span><br />
-<span class="pad2">2. <span class="bold">Non-branched.</span></span></p>
-
-<p>The branched and non-branched are divided into four classes:<br />
-<span class="pad2">1. <span class="bold">Non-porous and non-striated.</span></span><br />
-<span class="pad2">2. <span class="bold">Porous and non-striated.</span></span><br />
-<span class="pad2">3. <span class="bold">Striated and non-porous.</span></span><br />
-<span class="pad2">4. <span class="bold">Porous and striated.</span></span></p>
-
-<h5 id="CRYSTAL-BEARING_BAST_FIBRES">CRYSTAL-BEARING BAST FIBRES</h5>
-
-<p>The <span class="bold">crystal-bearing fibres</span> are composed (1) of groups of
-fibres, (2) of crystal cells, and (3) of crystals. In these cases
-the groups of fibres are large, and they are frequently completely
-covered by crystal cells, which may or may not contain a crystal.
-The crystals found on the fibres from the different plants vary
-considerably in size and form. As a rule, the fibres when separated
-are free of crystal cells and crystals. This is so because
-the crystal cells are exterior to the fibres, and in separating the
-fibres during the milling process the crystal cells are broken down
-and removed from the fibres. It is common, therefore, to find
-isolated fibres and crystals associated with the crystal-bearing
-fibres. The fibres which are crystal-bearing may be striated
-or porous, etc.; but owing to the fact that the grouping of the
-fibres and crystals is so characteristic, little or no attention is
-paid to the structure of the individual fibres.</p>
-
-<p><span class="pagenum" id="Page_91">[91]</span></p>
-
-<div class="figcenter illowp55" id="plate19" style="max-width: 46.5625em;">
-  <img class="w100 p1" src="images/plate19.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 19</span><br />
-<span class="smcap">Crystal-Bearing Fibres of Barks</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Frangula (<i lang="la" xml:lang="la">Rhamnus frangula</i>, L.).<br />
-2. Cascara sagrada (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D.C.).<br />
-3. Spanish licorice (<i lang="la" xml:lang="la">Glycyrrhiza glabra</i>, L.).<br />
-4. Witch-hazel bark (<i lang="la" xml:lang="la">Hamamelis virginiana</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_92">[92]</span></p>
-
-<p><span class="bold">Crystal-bearing fibres</span> occur in the barks of frangula (Plate
-19, Fig. 1); cascara sagrada (Plate 19, Fig. 2); witch-hazel
-(Plate 19, Fig. 4); in cocillana (Plate 20, Fig. 1); in white oak
-(Plate 20, Fig. 2); in quebracho (Plate 20, Fig. 3); and in
-Spanish licorice root (Plate 19, Fig. 3).</p>
-
-<p>The crystal-bearing fibres of leaves are always associated
-with vessels or tracheids and with cells with chlorophyl. The
-presence or absence of crystal-bearing fibres in leaves should
-always be noted. The crystal-bearing fibres of leaves are
-composed of fragments of conducting cells, fibres, crystal cells,
-and crystals. The crystal-bearing fibres of leaves occur in
-larger fragments than the other parts of the leaf, because the
-fibres are more resistant to powdering. Having observed that
-a leaf has crystal-bearing fibres, in order to identify the powder
-it is necessary to locate one of the other diagnostic elements
-of the leaf&mdash;as the papillæ of coca (Plate 21, Fig. 1), or the hair
-of senna (Plate 21, Fig. 3), or the vessels in eucalyptus (Plate 21,
-Fig. 2).</p>
-
-<p><span class="bold">Branched bast fibres</span> occur in only a few of the medicinal
-plants, notable examples being tonga root and sassafras root.
-Occasionally one is found in mezereum bark.</p>
-
-<p>The bast fibre of tonga root (Plate 22, Fig. 2) often has seven
-branches, but four- and five-branched forms are more common.
-The walls are non-porous, non-striated, and nearly white.</p>
-
-<p>The bast fibre of sassafras (Plate 22, Fig. 1) has thick, non-porous,
-and non-striated walls, and the branching occurs usually
-at one end only of the fibre. Most of the bast fibres of sassafras
-root are non-branched.</p>
-
-<h5 id="POROUS_AND_STRIATED_BAST_FIBRES">POROUS AND STRIATED BAST FIBRES</h5>
-
-<p><span class="bold">Porous and striated</span> walled bast fibres occur in blackberry
-bark of root, wild-cherry bark, and in cinchona bark.</p>
-
-<p>The fibres of blackberry root bark (Plate 23, Fig. 1) have
-distinctly porous and striated walls; the cavity, which is usually
-greater than the diameter of the wall, contains starch. These
-fibres usually occur as fragments.</p>
-
-<p>In wild-cherry bark (Plate 23, Fig. 2) the fibre has short,
-thick, unequally thickened walls, which are porous and striated.
-Most of the fibres are unbroken.</p>
-
-<p><span class="pagenum" id="Page_93">[93]</span></p>
-
-<div class="figcenter illowp55" id="plate20" style="max-width: 46em;">
-  <img class="w100 p1" src="images/plate20.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 20</span><br />
-<span class="smcap">Crystal-Bearing Fibres of Barks</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Cocillana (<i lang="la" xml:lang="la">Guarea rusbyi</i>, [Britton] Rusby).<br />
-2. White oak (<i lang="la" xml:lang="la">Quercus alba</i>, L.)<br />
-3. Quebracho (<i lang="la" xml:lang="la">Aspidosperma quebracho-blanco</i>, Schlechtendal).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_94">[94]</span></p>
-
-<div class="figcenter illowp52" id="plate21" style="max-width: 43.9375em;">
-  <img class="w100 p1" src="images/plate21.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 21</span><br />
-<span class="smcap">Crystal-Bearing Fibres of Leaves</span>
-
-<div class="blockquotc"><p class="noindent">1. Coca leaf (<i lang="la" xml:lang="la">Erythroxylon coca</i>, Lam.).<br />
-2. Eucalyptus leaf (<i lang="la" xml:lang="la">Eucalyptus globulus</i>, Labill).<br />
-3. Senna leaf (<i lang="la" xml:lang="la">Cassia angustifolia</i>, Vahl.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_95">[95]</span></p>
-
-<div class="figcenter illowp51" id="plate22" style="max-width: 43.125em;">
-  <img class="w100 p1" src="images/plate22.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 22</span><br />
-<span class="smcap">Branched Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Sassafras root bark (<i lang="la" xml:lang="la">Sassafras variifolium</i>, [Salisb.] Kuntze).<br />
-2. Tonga root.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_96">[96]</span></p>
-
-<p>Yellow cinchona bark (Plate 23, Fig. 3) has very thick,
-prominently striated porous-walled fibres, with either blunt or
-pointed ends. The cavity is narrow, and the pores are simple
-or branched.</p>
-
-<h5 id="POROUS_AND_NON-STRIATED_BAST_FIBRES">POROUS AND NON-STRIATED BAST FIBRES</h5>
-
-<p><span class="bold">Porous and non-striated</span> bast fibres occur in marshmallow
-root and echinacea root.</p>
-
-<p>The fibres of marshmallow (Plate 24, Fig. 3) usually occur
-in fragments. The walls have simple pores, and the diameter
-of the cell cavity is very wide; the pores on the upper or lower
-wall are circular or oval in outline (end view).</p>
-
-<p>The bast fibres of echinacea root (Plate 24, Fig. 4) are seldom
-broken; the walls are yellow, the pores are simple and numerous.
-The edges and surface of the fibres are frequently covered with
-a black intercellular substance.</p>
-
-<h5 id="NON-POROUS_AND_STRIATED_BAST_FIBRES">NON-POROUS AND STRIATED BAST FIBRES</h5>
-
-<p><span class="bold">Non-porous and striated</span> bast fibres occur in elm bark,
-stillingia root, and cundurango bark. The bast fibres of elm
-bark (Plate 25, Fig. 1) occur in broken, curved, or twisted fragments.
-The central cavity is very small, and the walls are
-longitudinally striated.</p>
-
-<p>In powdered stillingia root (Plate 25, Fig. 2) the bast fibres
-are broken, and the wall is very thick and longitudinally striated.
-The central cavity is small and usually not visible. Bast fibres
-of cundurango (Plate 25, Fig. 3) are broken in the powder.
-The cavity is very narrow, and the striations are arranged
-spirally, less frequently transversely.</p>
-
-<h5 id="NON-POROUS_AND_NON-STRIATED_BAST_FIBRES">NON-POROUS AND NON-STRIATED BAST FIBRES</h5>
-
-<p><span class="bold">Non-porous and non-striated</span> walled bast fibres occur in
-mezereum bark, in Ceylon cinnamon, in sassafras root bark,
-and in soap bark.</p>
-
-<p>The simplest non-porous and non-striated walled bast fibres
-are found in mezereum bark (Plate 26, Fig. 4). The individual
-fibre is very long. It often measures over three millimeters in
-length, so that in the powder the fibre is usually broken. The
-wall is non-lignified, white, non-porous, and of uniform diameter.</p>
-
-<p><span class="pagenum" id="Page_97">[97]</span></p>
-
-<div class="figcenter illowp52" id="plate23" style="max-width: 43.9375em;">
-  <img class="w100 p1" src="images/plate23.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 23</span><br />
-<span class="smcap">Porous and Striated Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Blackberry root (<i lang="la" xml:lang="la">Rubus cuneifolius</i>, Pursh.).<br />
-2. Wild cherry (<i lang="la" xml:lang="la">Prunus serotina</i>, Ehrh.).<br />
-3. Yellow cinchona (<i lang="la" xml:lang="la">Cinchona species</i>).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_98">[98]</span></p>
-
-<div class="figcenter illowp50" id="plate24" style="max-width: 42.3125em;">
-  <img class="w100 p1" src="images/plate24.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 24</span><br />
-<span class="smcap">Porous and Non-Striated Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Sarsaparilla root (Hypoderm), (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-2. Unicorn root (Endoderm).<br />
-3. Marshmallow root (<i lang="la" xml:lang="la">Althæa officinalis</i>, L.).<br />
-4. Echinacea root (<i lang="la" xml:lang="la">Echinacea angustifolia</i>, D. C.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_99">[99]</span></p>
-
-<div class="figcenter illowp51" id="plate25" style="max-width: 43em;">
-  <img class="w100 p1" src="images/plate25.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 25</span><br />
-<span class="smcap">Non-Porous and Striated Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Elm bark (<i lang="la" xml:lang="la">Ulmus fulva</i>, Michaux).<br />
-2. Stillingia root (<i lang="la" xml:lang="la">Stillingia sylvatica</i>, L.).<br />
-3. Cundurango root bark (<i lang="la" xml:lang="la">Marsdenia cundurango</i>, [Triana] Nichols).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_100">[100]</span></p>
-
-<p>In Ceylon cinnamon (Plate 26, Fig. 2) the bast fibres measure
-up to .900 mm. in length, so that in powdering the bark the
-fibre is rarely broken. These bast fibres, unlike the bast fibres
-of mezereum, have thick, white walls and a narrow cell cavity.
-Both ends of the fibre taper gradually to a long, narrow point.</p>
-
-<p>In Saigon cinnamon the bast fibres are not as numerous
-as they are in Ceylon cinnamon. The individual fibres are
-thicker than in Ceylon cinnamon, and the walls are yellowish
-and rough and the ends bluntly pointed. These fibres are rarely
-ever free from adhering fragments of parenchyma tissue.</p>
-
-<p>In sassafras root bark (Plate 26, Fig. 3) the fibre has one
-nearly straight side&mdash;the side in contact with the other bast
-fibres&mdash;and an outer side with a wavy outline, caused by the
-fibre’s pressing against parenchyma cells, the point of highest
-elevation being the point of the fibre’s growth into the intercellular
-space between two cells. The outer part of the wall
-tapers gradually at either end to a sharp point. The walls
-are white, thick, and non-porous.</p>
-
-<p>In soap bark (Plate 26, Fig. 1) the bast fibres have thick,
-white, wavy walls and a narrow cavity. One end of the cell is
-frequently somewhat blunt while the opposite end is slightly
-tapering.</p>
-
-<p>The branched stone cells of wild-cherry bark have three or
-more branches. The pores are small and usually non-branched,
-and the striations are very fine and difficult to see unless the
-iris diaphragm is nearly closed. The central cavity is very
-narrow and frequently contains brown tannin.</p>
-
-<p>The branched stone cells of hemlock bark are very large;
-the walls are white and distinctly porous bordering on the cell
-cavity, which contains bright reddish-brown masses of tannin.</p>
-
-<p>In cross-section bast fibres occur singly or isolated, as in
-Saigon cinnamon (Plate 34, Fig. 1); or in groups, as in menispermum
-(Plate 27, Figs. 1 and 2); or in the form of continuous
-bands, as in buchu stem (Plate 100, Fig. 5).</p>
-
-<p>Bast fibres are seen in longitudinal view in powdered drugs.
-The cell cavity shows throughout the length of the fibre. This
-cavity differs greatly in different fibres. In soap bark (Plate
-26, Fig. 1) there is scarcely any cell cavity, while in mezereum
-bark (Plate 26, Fig. 4) the cell cavity is very large.</p>
-
-<p><span class="pagenum" id="Page_101">[101]</span></p>
-
-<div class="figcenter illowp38" id="plate26" style="max-width: 32.375em;">
-  <img class="w100 p1" src="images/plate26.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 26</span><br />
-<span class="smcap">Non-Porous and Non-Striated Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Soap bark (<i lang="la" xml:lang="la">Quillaja saponaria</i>, Molina).<br />
-2. Ceylon cinnamon bark (<i lang="la" xml:lang="la">Cinnamomum zeylanicum</i>, Nees).<br />
-3. Sassafras root bark (<i lang="la" xml:lang="la">Sassafras variifolium</i>, [Salisb.] Kuntze).<br />
-4. Mezereum bark (<i lang="la" xml:lang="la">Daphne mezereum</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_102">[102]</span></p>
-
-<div class="figcenter illowp62" id="plate27" style="max-width: 52.1875em;">
-  <img class="w100 p1" src="images/plate27.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 27</span><br />
-<span class="smcap">Groups of Bast Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Menispermum rhizome (<i lang="la" xml:lang="la">Menispermum canadensis</i>, L.).<br />
-2. Althea root (<i lang="la" xml:lang="la">Althæa officinalis</i>, L.) showing two groups of bast fibres.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_103">[103]</span></p>
-
-<p>The pores, which are absent in many drugs, are, when
-present, either simple, as in echinacea root (Plate 24, Fig. 4),
-or they are branched, as in yellow cinchona (Plate 23, Fig. 3).</p>
-
-<p>In each of the above fibres the length and width of the
-fibre are shown. The fibres also have pores of variable length.
-Such a variation is common to most fibres with pores. That
-part of the wall immediately over or below the cell cavity shows
-the end view or diameter of the pore, as in the fibre of marshmallow
-root (Plate 24, Fig. 3). As a rule, however, the pores
-show indistinctly on the upper and lower wall.</p>
-
-<h5 id="OCCURRENCE_IN_POWDERED_DRUGS">OCCURRENCE IN POWDERED DRUGS</h5>
-
-<p>In powdered drugs bast fibres occur singly or in groups.
-The individual fibres may be broken, as in mezereum and elm
-bark, or they may be entire, as in Ceylon cinnamon and in
-sassafras bark (Plate 26, Figs. 2 and 3).</p>
-
-<p>The lignified walls of bast fibres are colored red by a solution
-of phlorogucin and hydrochloric acid, and the walls are stained
-yellow by aniline chloride.</p>
-
-<p>In fact, few of the fibres found in individual plants occur
-in a broken condition.</p>
-
-<p>Isolated bast fibres are circular in outline. Bast fibres, when
-forming part of a bundle, have angled outlines when they are
-completely surrounded by other bast fibres; but when they
-occur on the outer part of the bundle, and when in contact with
-parenchyma or other cortical cells, they are partly angled and
-partly undulated in outline.</p>
-
-<p>In the bast fibres the pores are placed at right angles to
-the length of the fibre. The side walls show the length of the
-pore (Plate 24, Fig. 3); while the upper or lower wall shows the
-outline, which is circular, and the pore, which is very minute.</p>
-
-<p>Most bast fibres have no cell contents. In some cases,
-however, starch occurs, as in the bast fibres of rubus.</p>
-
-<p>The color of the bast fibres varies, being colorless, as in
-Ceylon cinnamon; or yellowish-white, as in echinacea; or bright
-yellow, as in bayberry bark.</p>
-
-<p>Bast fibres retain their living-cell contents until fully developed;
-then they die and function largely in a mechanical
-way.</p>
-
-<p><span class="pagenum" id="Page_104">[104]</span></p>
-
-<p>The walls of bast fibres are composed of cellulose or of lignin.
-Most of the bast fibres occurring in the medicinal plants give
-a strong lignin reaction.</p>
-
-<h4 id="WOOD_FIBRES">WOOD FIBRES</h4>
-
-<p><span class="bold">Wood fibre</span>s always occur in cross-sections associated with
-vessels and wood parenchyma, from which they are distinguished
-by their thicker walls, smaller diameter, and by the
-nature of the pores, which are usually oblique and fewer in
-number than the pores in the walls of wood parenchyma, and
-different in form from the pores of vessels.</p>
-
-<p>The wood fibre on cross-section (Plate 105, Fig. 4) shows
-an angled outline, except in the case of the fibres bordering the
-pith-parenchyma, etc., in which case they are rounded on their
-outer surface, but angled at the points in contact with other
-fibres. The pore of wood fibres is one of the main characteristics
-which enable one to distinguish the wood fibres from bast fibres.</p>
-
-<p>The pores are slanting or strongly oblique (Plate 28, Fig. 2),
-and they show for their entire length on the broadest part of
-the wall&mdash;<em>i.e.</em>, the upper or the lower surface&mdash;while in the side
-wall they are oblique; but they are not so distinct as they are
-on the broad part of the wall.</p>
-
-<p>Frequently the pores appear crossed when the upper and
-the lower wall are in focus, because the pores are spirally arranged,
-and the pore on the under wall throws a shadow across
-the pore on the upper wall, or <em>vice versa</em>.</p>
-
-<p>Wood fibres always occur in a broken condition (Plate 28,
-Fig. 1) in powdered drugs. These broken fibres usually occur
-both singly and in groups in a given powder.</p>
-
-<p>The color of wood fibres varies greatly in the different medicinal
-woods. Fragments of wood are usually adhering to
-witch-hazel, black haw, and other medicinal barks. In each of
-these cases the wood fibres are nearly colorless. In barberry
-bark adhering fragments of wood and the individual fibres are
-greenish-yellow. The wood fibres of santalum album are whitish-brown;
-of quassia, whitish-yellow; <ins class="corr" id="tn104" title="Transcriber’s Note—“of logwood and santalum rubum” changed to “of logwood and santalum rubrum”.">of logwood and santalum rubrum</ins>,
-red.</p>
-
-<p><span class="pagenum" id="Page_105">[105]</span></p>
-
-<div class="figcenter illowp53" id="plate28" style="max-width: 44.25em;">
-  <img class="w100 p1" src="images/plate28.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 28</span><br />
-<span class="smcap">Wood Fibres</span>
-
-<div class="blockquotc">
-<p class="noindent">1. White sandalwood (<i lang="la" xml:lang="la">Santalum album</i>, L.).<br />
-2. Quassia wood (<i lang="la" xml:lang="la">Picræna excelsa</i>, [Swartz] Lindl.).<br />
-3. Logwood with crystals (<i lang="la" xml:lang="la">Hæmatoxylon campechianum</i>, L.).<br />
-4. Black haw root (<i lang="la" xml:lang="la">Viburnum prunifolium</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_106">[106]</span></p>
-
-<p>Some wood fibres function as storage cells. In quassia the
-wood fibres frequently contain storage starch. The wood fibres
-of logwood and red saunders contain coloring substances, which
-are partially in the cell cavity and partially in the cell wall.</p>
-
-<p>The walls of wood are composed largely of lignin.</p>
-
-<h4 id="COLLENCHYMA_CELLS">COLLENCHYMA CELLS</h4>
-
-<p><span class="bold">Collenchyma cells</span> form the principal medicinal tissue of
-stems of herbs, petioles of leaves, etc. In certain herbs the
-collenchyma forms several of the outer layers of the cortex of
-the stem. In motherwort, horehound, and in catnip the collenchyma
-cells occur chiefly at the angles of the stem. In
-motherwort (Plate 29, Fig. B) there are twelve bundles, one
-large bundle at each of the four angles, and two small bundles,
-one on either side of the large bundle. In catnip (Plate 29,
-Fig. A) there are four large masses, one at each angle of
-the stem.</p>
-
-<p>Collenchyma cells differ from parenchyma cells in a number
-of ways: first, the cell cavity is smaller; secondly, the walls
-are thicker, the greater amount of thickening being at the angles
-of the cells&mdash;that is, the part of the cell wall which is opposite
-the usual intercellular space of parenchyma cells, while the wall
-common to two adjoining cells usually remains unthickened.
-In horehound stem (Plate 30, Fig. 2) the thickening is so great
-at the angles that no intercellular space remains. In the side
-column of motherwort stem (Plate 30, Fig. 1) the thickening
-between the cells has taken place to such an extent that the
-cell cavities become greatly separated and arranged in parallel
-concentric rows.</p>
-
-<p>The collenchyma of the outer angle of motherwort stem
-(Plate 30, Fig. 3) is greatly thickened at the angles. There
-are no intercellular spaces between the cells, and cell cavity
-is usually angled in outline instead of circular, as in the cells
-of horehound. In certain plants intercellular spaces occur between
-the cells, and the walls are striated instead of being non-striated,
-as in the stems of horehound, motherwort, and
-catnip.</p>
-
-<p><span class="pagenum" id="Page_107">[107]</span></p>
-
-<div class="figcenter illowp100" id="plate29" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate29.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 29</span><br />
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Diagrammatic sketch of <ins class="corr" id="tn107" title="Transcriber’s Note—“the cross-section of catnip stem Nepeta cateria” changed to “the cross-section of catnip stem Nepeta cataria”.">the cross-section of catnip stem <i lang="la" xml:lang="la">Nepeta cataria</i></ins>, L.).
-1. Collenchyma occurring at the four angles
-of the stem.<br />
-<em>B.</em> Diagrammatic sketch of the cross-section of motherwort stem
-(<i lang="la" xml:lang="la">Leonurus cardiaca</i>, L.). 1, 2, 3. Twelve masses of collenchyma
-tissue occurring at the four sides of the stem.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_108">[108]</span></p>
-
-<div class="figcenter illowp53" id="plate30" style="max-width: 44.625em;">
-  <img class="w100 p1" src="images/plate30.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 30</span><br />
-<span class="smcap">Collenchyma Cells</span>
-
-<div class="blockquotc">
-<p>1. Cross-section of a side column of the collenchyma of motherwort stem (<i lang="la" xml:lang="la">Leonurus cardiaca</i>, L.).<br />
-<span class="pad1">2.</span> Cross-section of the collenchyma of horehound stem (<i lang="la" xml:lang="la">Marrubium
-vulgare</i>, L.).<br />
-<span class="pad1">3.</span> Cross-section of the collenchyma of the outer angle of motherwort stem.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_109">[109]</span></p>
-
-<p>Collenchyma cells retain their living contents at maturity.
-Many collenchyma cells, particularly of the outer layers of
-bark and the collenchyma of the stems of herbs, contain
-chlorophyll.</p>
-
-<p>The walls of collenchyma consist of cellulose.</p>
-
-<h4 id="STONE_CELLS">STONE CELLS</h4>
-
-<p><span class="bold">Stone cells</span>, like bast fibres, are branched or non-branched.
-Each group is then separated into subgroups according to wall
-structure (whether striated, or pitted and striated, etc.), thickness
-of wall and of cell cavity, color of wall and of cell contents,
-absence of color and of cell contents, etc.</p>
-
-<h5>BRANCHED STONE CELLS</h5>
-
-<p><span class="bold">Branched stone cells</span> occur in a number of drugs. In witch-hazel
-bark (Plate 31, Fig. 2) the walls are thick, white, and very
-porous. In some cells the branches are of equal length; in
-others they are unequal. In the tea-leaf (Plate 31, Fig. 1) the
-walls are yellowish white and finely porous. When the lower
-wall is brought in focus, it shows numerous circular pits. These
-pits represent the pores viewed from the end. The branches
-frequently branch or fork.</p>
-
-<p>Branched stone cells also occur in coto bark, acer spicatum,
-star-anise, witch-hazel leaf, hemlock, and wild-cherry barks.</p>
-
-<p>Non-branched stone cells are divided into two main groups,
-as follows:</p>
-
-<p>1. Porous and striated stone cells, and,<br />
-<span class="pad1">2.</span> Porous and non-striated stone cells.</p>
-
-<h5>POROUS AND STRIATED STONE CELLS</h5>
-
-<p><span class="bold">Porous and striated</span> walled stone cells occur in ruellia root,
-winter’s bark, bitter root, allspice, and aconite. These stone
-cells are shown in Plate 33, Figs. 1, 2, 3, 4, and 5.</p>
-
-<p>The stone cells of ruellia root (Plate 32, Fig. 1) are greatly
-elongated, rectangular in form, with thick, white, strongly
-porous walls. The central cavity is narrow and is marked with
-prominent pores and striations.</p>
-
-<p>The stone cells of winter’s bark (Plate 32, Fig. 2) vary from
-elongated to nearly isodiametric. The pores are very large,
-the light yellowish wall is irregularly thickened, and the central
-cavity is very large. The pores are prominent.</p>
-
-<p><span class="pagenum" id="Page_110">[110]</span></p>
-
-<div class="figcenter illowp50" id="plate31" style="max-width: 42.25em;">
-  <img class="w100 p1" src="images/plate31.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 31</span><br />
-<span class="smcap">Branched Stone Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Tea leaf (<i lang="la" xml:lang="la">Thea sinensis</i>, L.).<br />
-2. Witch-hazel bark (<i lang="la" xml:lang="la">Hamamelis virginiana</i>, L.).<br />
-3. Hemlock bark (<i lang="la" xml:lang="la">Tsuga canadensis</i>, [L.] Carr).<br />
-4. Wild-cherry bark (<i lang="la" xml:lang="la">Prunus serotina</i>, Ehrh.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_111">[111]</span></p>
-
-<p>The stone cell of bitter root (Plate 32, Fig. 3) is nearly
-isodiametric. The walls are yellowish white and strongly porous
-and striated. The central cavity is about equal to the thickness
-of the walls.</p>
-
-<p>The stone cell of allspice (Plate 32, Fig. 4) is mostly rounded
-in form, and when the outer wall only is in focus it shows numerous
-round and elongated pores. The central cavity is filled
-with masses of reddish-brown tannin. The striations are very
-prominent.</p>
-
-<p>The diagnostic stone cell of aconite (Plate 32, Fig. 5) is
-rectangular or square in outline; the walls are yellowish and
-the central cavity has a diameter many times the thickness of
-the wall. The side and surface view of the pores is prominent,
-and the striations are very fine.</p>
-
-<h5>POROUS AND NON-STRIATED STONE CELLS</h5>
-
-<p><span class="bold">Porous and non-striated stone cells</span> occur in Ceylon cinnamon,
-in calumba root, in dogwood bark, in cubeb, and in echinacea
-root.</p>
-
-<p>The diagnostic stone cells of Ceylon cinnamon (Plate 33,
-Fig. 1) are nearly square in outline; the walls are strongly
-porous and the large central cavity frequently contains
-starch.</p>
-
-<p>The stone cells of calumba root (Plate 33, Fig. 2) vary in
-shape from rectangular to nearly square, and the walls are
-greenish yellow, unequally thickened, and strongly porous.
-The typical stone cells contain several prisms, usually four.</p>
-
-<p>The stone cells of dogwood bark (Plate 33, Fig. 3) have
-thick, white walls with simple and branched pores. The central
-cavity frequently branches and appears black when recently
-mounted, owing to the presence of air.</p>
-
-<p>The stone cells of cubeb (Plate 33, Fig. 4) are very small,
-mostly rounded in outline, with a great number of very fine
-simple pores which extend from the outer wall to the central
-cavity. The wall is yellow and very thick.</p>
-
-<p>The stone cells of echinacea root (Plate 33, Fig. 5) are very
-irregular in form; the walls are yellowish and porous, and the<span class="pagenum" id="Page_112">[112]</span>
-central cavity is very large. A black intercellular substance
-is usually adhering to portions of the outer wall.</p>
-
-<p>The color of the walls of the different stone cells is very
-variable. In Ceylon cinnamon and ruellia the walls are colorless;
-in zanthoxylium, light yellow; in rumex, deep yellow;
-in cascara sagrada, greenish yellow.</p>
-
-<p>The pores of stone cells, like the pores of bast fibres, are
-either simple or branched, and they may or may not extend
-through the entire wall. Many of the shorter pores extend for
-only a short distance from the cell cavity.</p>
-
-<p>The width of the cell cavity varies considerably in the stone
-cells of the different plants. In aconite (Plate 32, Fig. 5), in
-calumba (Plate 33, Fig. 2), and in Ceylon cinnamon (Plate 33,
-Fig. 1), the cell cavity is several times greater than the thickness
-of the cell wall.</p>
-
-<p>In allspice (Plate 32, Fig. 4), in bitter root (Plate 32, Fig.
-3), the diameter of the cell cavity and the thickness of the wall
-are about equal. In cubeb (Plate 33, Fig. 4), in ruellia (Plate
-32, Fig. 1), the wall is thicker than the diameter of the cell
-cavity.</p>
-
-<p>The cavity of many stone cells contains no characteristic
-cell contents. In other stone cells the cell contents are as
-characteristic as the stone cell. The stone cells of both Saigon
-and Ceylon cinnamon (Plate 33, Fig. 1) contain starch; the
-stone cells of calumba (Plate 33, Fig. 2) contain prisms of calcium
-oxalate; the stone cells of allspice and sweet-birch bark contain
-tannin.</p>
-
-<p>In cross-sections, stone cells occur singly, as in Saigon cinnamon
-(Plate 34, Fig. 1), ruellia (Plate 34, Fig. 2); in groups, as
-in cascara sagrada (Plate 34, Fig. 3); and in continuous bands,
-as in Saigon cinnamon (Plate 34, Fig. 4).</p>
-
-<p>In powdered drugs, stone cells, like bast fibres, occur singly,
-as in ruellia, calumba, etc.; or in groups, as in cascara sagrada,
-witch-hazel bark, etc. In most powders they occur both singly
-and in groups.</p>
-
-<p>The individual stone cells are mostly entire, as in ruellia,
-calumba, allspice, echinacea, etc. In cascara sagrada many of
-the stone cells are broken when the closely cemented groups
-are torn apart in the milling process. Many of the branched
-stone cells of witch-hazel bark and leaf, wild cherry, etc., also
-occur broken in the powder.</p>
-
-<p><span class="pagenum" id="Page_113">[113]</span></p>
-
-<div class="figcenter illowp52" id="plate32" style="max-width: 43.6875em;">
-  <img class="w100 p1" src="images/plate32.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 32</span><br />
-<span class="smcap">Porous and Striated Stone Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Ruellia root (<i lang="la" xml:lang="la">Ruellia ciliosa</i>, Pursh.).<br />
-2. Winter’s-bark (<i lang="la" xml:lang="la">Drimys winteri</i>, Forst.).<br />
-3. Bitterroot (<i lang="la" xml:lang="la">Apocynum androsæmifolium</i>, L.).<br />
-4. Allspice (<i lang="la" xml:lang="la">Pimenta officinalis</i>, Lindl.).<br />
-5. Aconite (<i lang="la" xml:lang="la">Aconitum napellus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_114">[114]</span></p>
-
-<div class="figcenter illowp56" id="plate33" style="max-width: 46.9375em;">
-  <img class="w100 p1" src="images/plate33.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 33</span><br />
-<span class="smcap">Porous and Non-striated Stone Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Ceylon cinnamon (<i lang="la" xml:lang="la">cinnamomum zeylanicum</i>, Nees).<br />
-2. Calumba root (<i lang="la" xml:lang="la">Jateorhiza palmata</i>, [Lam.] Miers).<br />
-3. Dogwood root bark (<i lang="la" xml:lang="la">Cornus florida</i>, L.).<br />
-4. Cubeb (<i lang="la" xml:lang="la">Piper cubeba</i>, L., f.)<br />
-5. Echinacea (<i lang="la" xml:lang="la">Echinacea angustifolia</i>, D.C.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_115">[115]</span></p>
-
-<div class="figcenter illowp53" id="plate34" style="max-width: 44.25em;">
-  <img class="w100 p1" src="images/plate34.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 34</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Saigon cinnamon.<br />
-2. Ruellia root (<i lang="la" xml:lang="la">Ruellia ciliosa</i>, Pursh.).<br />
-3. Cascara sagrada (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D.C.).<br />
-4. Saigon cinnamon.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_116">[116]</span></p>
-
-<p>The walls of all stone cells are composed of lignin.</p>
-
-<p>The form of stone cells varies greatly; in aconite the stone
-cells are quadrangular; in ruellia they are rectangular; in
-pimenta, they are circular or oval in outline; in most stone cells they
-are polygonal.</p>
-
-<p>The lignified walls of stone cells are stained red with a
-solution of phloroglucin and hydrochloric acid, and the walls
-are stained yellow by aniline chloride.</p>
-
-<h4 id="ENDODERMAL_CELLS">ENDODERMAL CELLS</h4>
-
-<p>The <span class="bold">endodermal cells</span> of the different plants vary greatly
-in form, color, structure, and composition of the wall, yet these
-different endodermal cells may be divided into two groups:
-first, thin-walled parenchyma-like cells, and secondly, thick-walled
-fibre-like cells. In the thin-walled endodermal cells the
-walls are composed of cellulose, and the cell terminations are
-blunt or rounded. When the drug is powdered, the cells break
-up into small diagnostic fragments. In the thick-walled endodermal
-cells, the walls are lignified and porous, and the ends of
-the cell are frequently pointed and resemble fibres.</p>
-
-<p>Sarsaparilla root, triticum, convallaria, and aletris have
-thick-walled endodermal cells.</p>
-
-<h5>STRUCTURE OF ENDODERMAL CELLS</h5>
-
-<p>The endodermal cells of sarsaparilla root (Plate 35, Fig. 1)
-are never more than one layer in thickness. The walls are
-porous and of a yellowish-brown color. Alternating with the
-thick-walled cell is a thin-walled cell, which is frequently referred
-to as a passage cell.</p>
-
-<p>The endodermal cells of triticum (Plate 35, Fig. 2) are yellowish,
-and the walls are porous and striated. There are one or two
-layers of cells. The cells forming the outer layer have very
-thin outer but thick inner walls, while the cells forming the
-inner layer are more uniform in thickness.</p>
-
-<p>The endodermal cells of convallaria (Plate 35, Fig. 3) are
-yellowish white in color, and the walls are porous and striated.
-The outer wall of the layer of cells is thinner than the inner
-wall. The innermost layer of cell is more uniformly thickened.</p>
-
-<p><span class="pagenum" id="Page_117">[117]</span></p>
-
-<div class="figcenter illowp53" id="plate35" style="max-width: 44.3125em;">
-  <img class="w100 p1" src="images/plate35.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 35</span><br />
-<span class="smcap">Cross-Sections of Endodermal Cells of</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-2. Triticum (<i lang="la" xml:lang="la">Agropyron repens</i>, L.).<br />
-3. Convallaria (<i lang="la" xml:lang="la">Convallaria majalis</i>, L.).<br />
-4. Aletris (<i lang="la" xml:lang="la">Aletris farinosa</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_118">[118]</span></p>
-
-<p>The endodermal cells of aletris (Plate 35, Fig. 4) are yellowish
-brown, slightly porous and striated. There are one or two
-layers of these cells, and two of the smaller cells usually occupy
-a space similar to that occupied by the radically elongated
-single cell.</p>
-
-<p>On a longitudinal view, the endodermal cells of sarsaparilla
-triticum, convallaria, and aletris appear as follows:</p>
-
-<p>Those of sarsaparilla (Plate 36, Fig. 1) are greatly elongated,
-the ends of the cells are blunt or slightly pointed, and the walls
-appear porous and striated.</p>
-
-<p>Those of triticum (Plate 36, Fig. 2) are elongated, the walls
-are porous and striated, and the outer wall is much thinner
-than the inner wall. The end wall between two cells frequently
-appears common to the two cells.</p>
-
-<p>Those of convallaria (Plate 36, Fig. 3) are elongated, and
-the end wall is usually blunt. The outer wall is thinner than
-the inner wall.</p>
-
-<p>Those of aletris (Plate 36, Fig. 4) are fibre-like in appearance;
-the ends of the cells are pointed and the wall is strongly
-porous. The longitudinal view of these cells is shown in plate 36.</p>
-
-<h4 id="HYPODERMAL_CELLS">HYPODERMAL CELLS</h4>
-
-<p><span class="bold">Hypodermal cells</span> occur in sarsaparilla root and in triticum.
-In the cross-section of sarsaparilla root (Plate 37, Fig. 1) the
-hypodermal cells are yellowish or yellowish brown. The outer
-wall is thicker than the inner wall, and the cell cavity is mostly
-rounded, and contains air. The walls are porous and finely
-striated. On longitudinal view, the hypodermal cells of sarsaparilla
-(Plate 37, Fig. 2) are greatly elongated, and the outer and
-side walls are thicker than the inner walls. The ends of the
-cells are blunt and distinct from each other.</p>
-
-<p>In cross-section, the hypodermal cells of triticum (Plate 37,
-Fig. 3) are nearly rounded in outline, and the walls are of nearly
-uniform thickness. In longitudinal view (Plate 37, Fig. 4)
-the same cells appear parenchyma-like, and the walls between
-any two cells appear common to the two cells.</p>
-
-<p><span class="pagenum" id="Page_119">[119]</span></p>
-
-<div class="figcenter illowp55" id="plate36" style="max-width: 46.5625em;">
-  <img class="w100 p1" src="images/plate36.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 36</span><br />
-<span class="smcap">Longitudinal Sections of Endodermal Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-2. Triticum (<i lang="la" xml:lang="la">Agropyron repens</i>, L.).<br />
-3. Convallaria (<i lang="la" xml:lang="la">Convallaria majalis</i>, L.).<br />
-4. Aletris (<i lang="la" xml:lang="la">Aletris farinosa</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_120">[120]</span></p>
-
-<div class="figcenter illowp52" id="plate37" style="max-width: 43.6875em;">
-  <img class="w100 p1" src="images/plate37.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 37</span><br />
-<span class="smcap">Hypodermal Cells</span>
-
-<div class="blockquotc">
-<p class="noindent">1. <ins class="corr" id="tn120" title="Transcriber’s Note—“Cross-section sarsaparilla root Smilex officinalis” changed to “Cross-section sarsaparilla root Smilax officinalis”.">Cross-section sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i></ins>,
-Kunth).<br />
-2. Longitudinal section sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-3. Cross-section triticum (<i lang="la" xml:lang="la">Agropyron repens</i>, L.).<br />
-4. Longitudinal section triticum (<i lang="la" xml:lang="la">Agropyron repens</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_121">[121]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_IV">CHAPTER IV<br />
-<span class="fs80">ABSORPTION TISSUE</span></h3>
-</div>
-
-<p>Most plants obtain the greater part of their food, first, from
-the soil in the form of a watery solution, and, secondly, from the
-air in the form of a diffusible gas. In a few cases all food
-material is obtained from the air, as in the case of epiphytic
-plants. In such plants, the aerial roots have a modified outer
-layer&mdash;velamen&mdash;which functions as a water-absorbing and gas-condensing
-tissue. Many xerophytic plants absorb water
-through the trichomes of the leaf. Such absorption tissue
-enables the plant to absorb any moisture that may condense
-upon the leaf and that would not otherwise be available to the
-plant. The water-absorbing tissue of roots is restricted to the
-root hairs, which are found, with few exceptions, only on young
-developing roots.</p>
-
-<h4 id="ROOT_HAIRS">ROOT HAIRS</h4>
-
-<p><span class="bold">Root hairs</span> usually occur a short distance back of the root
-cap. There is, in fact, a definite zone of the epidermis on which
-the root hairs develop. This zone is progressive. As the root
-elongates the root hairs continue to develop, the zone of hairs
-always remaining at about the same distance from the root
-cap. With the development of new zones of growth the hairs
-on the older zone die off and finally become replaced by an epidermis,
-or a periderm, except in the case of sarsaparilla root, and
-possibly other roots that have persistent root hairs.</p>
-
-<p>Each root hair is an outgrowth from an epidermal cell (Plate
-38, Fig. 3). The length of the hair and its form depend upon
-the nature of the soil, whether loose or compact, and upon the
-amount of water present.</p>
-
-<p>A root hair is formed by the extension of the peripheral wall
-of an epidermal cell. At first this wall is only slightly papillate,
-but gradually the end wall is extended farther and farther from<span class="pagenum" id="Page_122">[122]</span>
-the surface of the root, caused by the development of side
-walls by the growing tip of the root hair until a tube-like structure,
-root hair, is produced. The root hair is then a modified
-epidermal cell. The protoplast lines the cell, and the central
-part of the root hair consists of a large vacuole filled with cell
-sap. The wall of the root hair is composed of cellulose, and
-the outermost part is frequently mucilaginous. As the root
-hairs develop, they become bent, twisted, and of unequal diameter,
-as a result of growing through narrow, winding soil
-passages. During their growth, the root hairs become firmly
-attached to the soil particles. The walls of root hairs give an
-acid reaction caused by the solution of the carbon dioxide excreted
-by the root hair. The acid character of the wall attracts
-moisture, and in addition has a solvent action on the insoluble
-compounds contained in the soil. It will thus be seen that the
-method of growth, structure, composition, and reaction of the
-wall of the root hair is perfectly suited to carry on the work
-of absorbing the enormous quantities of water needed by the
-growing plant. It is a well-known fact that when two solutions
-of unequal density are separated by a permeable membrane,
-the less dense liquid will pass through the membrane to the
-denser liquid. The wall of the root hair acts like an osmotic
-membrane. The less dense watery solution outside the root
-hair passes through its wall and into the denser cell sap solution.
-As the solution is absorbed, it passes from the root hair into
-the adjoining cortical parenchyma cells.</p>
-
-<p>It is a fact that root hairs are seldom found in abundance
-on medicinal roots. This is due to the fact that root hairs
-occur only on the smaller branches of the root, and that when
-the root is pulled from the ground the smaller roots with their
-root hairs are broken off and left in the soil. For this reason
-a knowledge of the structure of root hairs is of minor importance
-in the study of powdered drugs. An occasional root hair is
-found, however, in most powdered roots, but root hairs have
-little or no diagnostic value, except in false unicorn root and
-sarsaparilla. When false unicorn root is collected, most of the
-root hairs remain attached to the numerous small fibrous roots,
-owing to the fact that these roots are easily removed from the
-sandy soil in which the plants grow. The root hairs of false
-unicorn are so abundant and so large that they form dense
-mats, which are readily seen without magnification. These
-hairs are, therefore, macroscopically as well as microscopically
-diagnostic. The root hairs of false unicorn (Plate 39, Fig. 2)
-have white, wavy, often decidedly indented walls. The terminal,
-or end wall, is rounded and much thicker than the side walls.</p>
-
-<p><span class="pagenum" id="Page_123">[123]</span></p>
-
-<div class="figcenter illowp75" id="plate38" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate38.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 38</span><br />
-<span class="smcap">Cross-Section of Sarsaparilla Root</span> (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth)
-
-<div class="blockquotc">
-<p class="noindent">1. Epidermal cell developing into a root hair.<br />
-2. Developing root hair.<br />
-3. Nearly mature root hair.<br />
-4. Hypodermal cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_124">[124]</span></p>
-
-<div class="figcenter illowp45" id="plate39" style="max-width: 38.125em;">
-  <img class="w100 p1" src="images/plate39.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 39</span><br />
-<span class="smcap">Root Hairs</span> (Fragments)
-
-<div class="blockquotc"><p class="noindent">1. Sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-2. False unicorn root (<i lang="la" xml:lang="la">Helonias bullata</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_125">[125]</span></p>
-
-<p>In sarsaparilla (Plate 39, Fig. 1) the root hairs are curved
-and twisted. The end wall is thicker than the side walls. In
-some hairs the walls are as thick as the walls of the thin-walled
-bast fibres. This accounts for the fact that the root hairs
-are persistent on even the older portions of sarsaparilla root,
-and it serves also to explain why these root hairs remain on
-the root even after being pulled from the firmly packed earth
-in which the root grows.</p>
-
-<h5>WATER ABSORPTION BY LEAVES</h5>
-
-<p>In many xerophytic terrestrial plants, the trichomes occurring
-on leaves act as a water-absorbing tissue. In such plants the
-walls of the hairs are composed largely of cellulose. It is obvious
-that these hairs absorb the water of condensation caused
-by dew and light rains&mdash;water which could not reach the plant
-except by such means.</p>
-
-<p>There is no special tissue set aside for the absorption of
-gases from the air. Carbon dioxide, which contributes the
-element carbon to the starch formed by photosynthesis, enters
-the leaf by way of the stoma and lenticels. The structure and
-the chief functions of these will be considered under aërating
-tissue.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_126">[126]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_V">CHAPTER V<br />
-<span class="fs80">CONDUCTING TISSUE</span></h3>
-</div>
-
-<p>All cells of which the primary or secondary function is that
-of conduction are included under conducting tissue. It will
-be understood how important the conducting tissue is when the
-enormous quantity of water absorbed by a plant during a
-growing season is considered. It will then be realized that
-the conducting system must be highly developed in order to
-transport this water from one organ to another, and, in fact,
-to all the cells of the plant. Special attention must be given to
-the occurrence, the structure, the direction of conduction, and
-to the nature of the conducted material.</p>
-
-<p>The cells or cell groups comprising the conducting tissue
-are vessels and tracheids, sieve tubes, medullary ray cells, latex
-tubes, and parenchyma.</p>
-
-<h4 id="VESSELS_AND_TRACHEIDS">VESSELS</h4>
-
-<p><span class="bold">Vessels</span> and <span class="bold">tracheids</span> form the principal upward conducting
-tissue of plants. They receive the soil water expressed
-from the cortical parenchyma cells located in the region of the
-root, immediately back of the root hair zone. This soil water,
-with dissolved crude inorganic and organic food materials, after
-entering the vessels and tracheids passes up the stem. The
-cells needing water at the different heights absorb it from the
-vessels, the excess finally reaching the leaves. When the stem
-branches, the water passes into the vessels of the branches and
-finally to the leaves of the branch. In certain special cases the
-vessels conduct upward soluble food material. In spring sugary
-sap flows upward through the vessels of the sugar maple.</p>
-
-<p>Vessels are tubes, often of great length, formed from a number
-of superimposed cells, in which the end walls have become
-absorbed. The vessels therefore offer little resistance to the
-transference of water from the roots to the leaves of a plant.<span class="pagenum" id="Page_127">[127]</span>
-The combined length of the vessels is about equal to the height
-of the plant in which they occur. The length of the individual
-vessels varies from a fraction of a meter up to several meters.</p>
-
-<h5 id="ANNULAR_VESSELS">ANNULAR VESSELS</h5>
-
-<p>The <span class="bold">annular vessels</span> are thickened at intervals in the form
-of rings (Plate 40, Fig. 1), which extend outward from and
-around the inner wall of the vessel. In fact, it is the inner wall
-which is thickened in all the different types of vessels. The
-ring-like thickening usually separates from the wall when the
-drug is powdered. Such separated rings occur frequently in
-powdered digitalis, belladonna, and stramonium leaves. Annular
-vessels are not, however, of diagnostic importance, because
-more characteristic cells are found in the plants in which
-they occur. Not infrequently a vessel will have annular thickenings
-at one end and spiral thickenings at the other. Such
-vessels are found in the pumpkin stem (Plate 40, Fig. 1).</p>
-
-<p>Vessels are distinguished from other cells by their arrangement,
-by their large size when seen in cross-section, and by the
-thickening of the wall when seen in longitudinal sections of the
-plant or in powders. The side walls of vessels are thickened in
-a number of striking yet uniform ways. The chief types of
-thickening of the wall, beginning with one that is the least
-thickened, are annular, spiral, sclariform, pitted, and pitted
-with bordered pores.</p>
-
-<h5 id="SPIRAL_VESSELS">SPIRAL VESSELS</h5>
-
-<p>In the <span class="bold">spiral vessel</span> the thickening occurs in the form of a
-spiral, which is readily separated from the side walls. This is
-particularly the case in powdered drugs, where the spiral thickening
-so frequently separates from the cell wall. There are
-three types of spiral vessels: those with one (Plate 41, Fig. 1),
-those with two, and those with three spirals. Single spirals
-occur in most leaves; double spirals occur in many plants
-(Plate 41, Fig. 2), but they are particularly striking in powdered
-squills. Triple spirals are characteristic of the eucalyptus
-leaf (Plate 41, Fig. 3); in fact, they form a diagnostic feature
-of the powder. Frequently a spirally thickened wall indicates
-a developmental stage of the vessel. Many such vessels are<span class="pagenum" id="Page_128">[128]</span>
-spirally thickened at first, but later, when mature, an increased
-amount of thickening occurs and the vessel becomes a reticulate
-or pitted vessel. Many mature vessels, however, are spirally
-thickened as indicated above. In herbaceous stems and in
-certain roots and leaves spiral vessels are associated with the
-sclariform reticulate and pitted type. In certain cases a single
-spiral band will branch as the vessel matures.</p>
-
-<p>There is a great variation in the amount of spiral thickening
-occurring in a vessel. In leaves, particularly, the spiral appears
-loosely coiled; while in squills and other rhizomes and roots
-the spiral appears as a series of rings. When viewed by high
-power only half of each spiral band is visible. At either side
-of the cell the exact size and form of the thickening appear in
-two parallel rows of dark circles or projections from the walls.
-This thickening of the wall is rendered visible from the fact
-that the light is retarded as it passes through that portion of the
-spiral extending from the upper to the under side of the spiral;
-while the light readily traverses the upper and lower cross bands
-of the vessel.</p>
-
-<p>It should be remembered that, when the upper part of the
-spiral vessel is in focus, the bands appear to bend in a direction
-away from the eye; while when the under side of the bands are
-in focus, the bands appear to bend toward the eye. These
-facts will show that it is necessary to focus on both the upper
-and lower walls in studying spiral vessels. In double spiral
-vessels the spirals are frequently coiled in opposite directions;
-therefore the bands appear to cross one another. In eucalyptus
-leaf the three bands are coiled in the same direction. In all
-cases the thickening occurs on all sides of the wall. Its appearance
-will, therefore, be the same no matter at what angle the
-vessel is viewed.</p>
-
-<h5 id="SCLARIFORM_VESSELS">SCLARIFORM VESSELS</h5>
-
-<p><span class="bold">Sclariform vessels</span> have interrupted bands of thickening on
-the inner walls. Two or more such bands occur between the
-two side walls. The series of bands are separated by uniformly
-thickened portions of the wall extending parallel to the length
-of the vessel. Sclariform vessels are usually quite broad, so
-that it is necessary to change the focus several times in order
-to bring the different series of bands in focus. The series of
-bands are usually of unequal width and length.</p>
-
-<p><span class="pagenum" id="Page_129">[129]</span></p>
-
-<div class="figcenter illowp48" id="plate40" style="max-width: 40.25em;">
-  <img class="w100 p1" src="images/plate40.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 40</span><br />
-<span class="smcap">Annular and Spiral Vessels</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Pumpkin stem (<i lang="la" xml:lang="la">Cucurbita pepo</i>, L.).<br />
-2. Two characteristic views of spiral vessels.<br />
-3. (<em>A</em>) Upper part of spiral vessel in focus.<br />
-<span style="margin-left: 1.0em;">(<em>B</em>) Under part of spiral vessel in focus.</span><br />
-4. Spiral vessel of the disk petal matricaria (<i lang="la" xml:lang="la">Matricaria</i><br />
-<span style="margin-left: 1.5em;"><i lang="la" xml:lang="la">chamomilla</i>, L.).</span></p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_130">[130]</span></p>
-
-<div class="figcenter illowp50" id="plate41" style="max-width: 41.9375em;">
-  <img class="w100 p1" src="images/plate41.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 41</span><br />
-<span class="smcap">Spiral Vessels</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Single spiral vessel of pumpkin stem (<i lang="la" xml:lang="la">Cucurbita pepo</i>, L.).<br />
-2. Double spiral vessel of squill bulb (<i lang="la" xml:lang="la">Urginea maritima</i>, [L.] Baker).<br />
-3. Triple spiral vessel of eucalyptus leaf (<i lang="la" xml:lang="la">Eucalyptus globulus</i>, Labill).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_131">[131]</span></p>
-
-<p>Sclariform vessels occur in male fern (Plate 42, Fig. 2),
-calamus, tonga root (Plate 42, Fig. 3), and sarsaparilla (Plate
-42, Fig. 1). In each they are characteristic. Sclariform vessels,
-with these few exceptions, do not occur in drug plants. In fact,
-drugs derived from dicotyledones rarely have sclariform vessels.
-They occur chiefly in the ferns and drugs derived from monocotyledenous
-plants. Their presence or absence should, therefore,
-be noted when studying powdered drugs.</p>
-
-<h5 id="RETICULATE_VESSELS">RETICULATE VESSELS</h5>
-
-<p><span class="bold">Reticulate vessels</span> are of common occurrence in medicinal
-plants. In fact, they occur more frequently than any other
-type of vessel. The basic structure of reticulate vessels (Plate
-43, Fig. 1) occurring in different plants is similar, but they vary
-in a recognizable way in different plants (Plate 43, Fig. 2).
-The walls of reticulate vessels are thickened to a greater extent
-than are the walls of spirally thickened vessels.</p>
-
-<h5 id="PITTED_VESSELS">PITTED VESSELS</h5>
-
-<p><span class="bold">Pitted vessels</span> are met with most frequently in woods and
-wood-stemmed herbs. There are two distinct types of pitted
-vessels&mdash;<em>i.e.</em>, simple pitted vessels and pitted vessels with
-bordered pores.</p>
-
-<p>The pitted vessel represents the highest type of cell-wall
-thickening. The entire wall of the vessel is thickened, with
-the exception of the places where the pits occur. The number
-and size of the pits vary greatly in different drugs. In quassia
-(Plate 44, Fig. 1) the pits are numerous and very small, and the
-openings are nearly circular in outline. In white sandalwood
-(Plate 44, Fig. 3). the pits are few in number, but when they
-do occur they are much larger than are the pits of quassia.</p>
-
-<h5 id="PITTED_VESSELS_WITH_BORDERED_PORES">PITTED VESSELS WITH BORDERED PORES</h5>
-
-<p><span class="bold">Pitted vessels with bordered pores</span> are of common occurrence
-in the woody stems and stems of many herbaceous plants
-(Plate 45, Figs. 3 and 4). In such vessels the wall is unthickened
-for a short distance around the pits. This unthickened portion
-may be either circular or angled in outline, a given form being
-constant to the plant in which it occurs. The pits vary from
-oval to circular. Pitted vessels with bordered pores occur in
-belladonna and aconite stems.</p>
-
-<p><span class="pagenum" id="Page_132">[132]</span></p>
-
-<div class="figcenter illowp54" id="plate42" style="max-width: 45.3125em;">
-  <img class="w100 p1" src="images/plate42.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 42</span><br />
-<span class="smcap">Sclariform Vessels</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).<br />
-2. Male fern (<i lang="la" xml:lang="la">Dryopteris marginalis</i>, [L.] A. Gray).<br />
-3. Tonga root.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_133">[133]</span></p>
-
-<div class="figcenter illowp53" id="plate43" style="max-width: 44.625em;">
-  <img class="w100 p1" src="images/plate43.jpg" alt="" />
-  <div class="caption"><div class="blockquotc">
-<span class="bold">PLATE 43</span><br />
-<span class="smcap">Reticulate Vessels</span>
-
-<p class="noindent">1. Hydrastis rhizome (<i lang="la" xml:lang="la">Hydrastis canadensis</i>, L.).<br />
-2. Musk root (<i lang="la" xml:lang="la">Ferula sumbul</i>, [Kauffm.] Hook., f.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_134">[134]</span></p>
-
-<div class="figcenter illowp56" id="plate44" style="max-width: 47.0625em;">
-  <img class="w100 p1" src="images/plate44.jpg" alt="" />
-  <div class="caption">PLATE 44<br />
-<span class="smcap">Pitted Vessels</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Quassia, low magnification (<i lang="la" xml:lang="la">Picræna excelsa</i>, [Swartz] Lindl.).<br />
-2. Quassia, high magnification.<br />
-3. White sandalwood (<i lang="la" xml:lang="la">Santalum album</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_135">[135]</span></p>
-
-<div class="figcenter illowp52" id="plate45" style="max-width: 43.375em;">
-  <img class="w100 p1" src="images/plate45.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 45</span><br />
-<span class="smcap">Vessels</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Reticulate vessel of calumba root (<i lang="la" xml:lang="la">Jateorhiza palmata</i>, [Lam.] Miers).<br />
-2. Reticulate tracheid of hydrastis rhizome (<i lang="la" xml:lang="la">Hydrastis canadensis</i>, L.).<br />
-3. Pitted vessel with bordered pores of belladonna stem.<br />
-4. Pitted vessel with bordered pores of aconite stem (<i lang="la" xml:lang="la">Aconitum napellus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_136">[136]</span></p>
-
-<p>Vessels and tracheids lose their living-cell contents when
-fully developed. In the vessels the cell contents disappear at
-the period of dissolution of the cell wall.</p>
-
-<p>The walls of vessels and tracheids are composed of lignin,
-a substance which prevents the collapsing of the walls when
-the surrounding cells press upon them, and which also prevents
-the tearing apart of the wall when the vessel is filled with ascending
-liquids under great pressure. Lignin thus enables the
-vessel to resist successively compression and tearing forces.</p>
-
-<p>Tracheids are formed from superimposed cells with oblique
-perforated end walls. The side walls of tracheids are thickened
-in a manner similar to those of vessels. The tracheids in golden
-seal are of a bright-yellow color, and groups of these short
-tracheids scattered throughout the field form the most characteristic
-part of the powdered drug. In ipecac root the tracheids
-are of a porcelain-white, translucent appearance, and they are
-much longer than are the tracheids of golden seal.</p>
-
-<p>The cellulose walls of parenchyma cells are stained blue
-with hæmatoxylin and by chlorzinciodide. Cellulose is completely
-soluble in a fresh copper ammonia solution.</p>
-
-<h4 id="SIEVE_TUBES">SIEVE TUBES</h4>
-
-<p><span class="bold">Sieve tubes</span> are downward-conducting cells. They conduct
-downward proteid food material. This fact is easily demonstrated
-by adding iodine to a section containing sieve tubes, in
-which case the sieve tubes are turned yellow.</p>
-
-<p>Developing sieve tubes have all the parts common to a living
-cell; but when fully mature, however, the nucleus becomes
-disorganized, but a layer of protoplasm continues to line the
-cell wall.</p>
-
-<p>Sieve tubes (Plate 46, Fig. 1) are composed of a great number
-of superimposed cells with perforated end walls and with non-porous
-cellulose side walls. The end walls of two adjoining
-cells are greatly thickened and the pores pass through both
-walls. This thickened part of the porous end walls of two sieve
-cells is called the sieve plate, and it may be placed in an oblique
-or a horizontal position.</p>
-
-<p><span class="pagenum" id="Page_137">[137]</span></p>
-
-<div class="figcenter illowp43" id="plate46" style="max-width: 36.5em;">
-  <img class="w100 p1" src="images/plate46.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 46</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Longitudinal section of sieve tube (<i lang="la" xml:lang="la">Cucurbita pepo</i>, L.).<br />
-2. Cross-section of sieve tube just above an end wall&mdash;sieve plate.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_138">[138]</span></p>
-
-<p>In a longitudinal section the sieve tubes are seen to be
-slightly bulging at the sieve plate, and through the pores extend
-protoplasmic strands. The strands are united on the upper
-and lower side of the sieve plate to form the protoplasmic strands
-of the living sieve tubes and the callus, layers of dried plants.
-This callus is frequently yellowish in color, and in all cases is
-separated from the cell wall. In certain plants the sieve plate
-occurs on the side walls of the sieve tubes in contact with other
-sieve tubes.</p>
-
-<h5 id="SIEVE_PLATE">SIEVE PLATE</h5>
-
-<p><span class="bold">Sieve plates</span> on cross-section (Plate 46, Fig. 2) are polygonal
-in outline, and the pores are either round or angled. Large
-sieve tubes and sieve plates occur in pumpkin stem; but, almost
-without exception, in drug plants the sieve tubes are small
-and the sieve plate is inconspicuous. When the drug is powdered,
-the sieve tubes break up into undiagnostic fragments.
-When studying sections of the plants, the extent, size, and
-arrangement of the sieve tubes must always be noted.</p>
-
-<h4 id="MEDULLARY_BUNDLES_RAYS_AND_CELLS">MEDULLARY BUNDLES, RAYS, AND CELLS</h4>
-
-<h5>Function</h5>
-
-<p>The medullary ray cells are the lateral conducting cells of
-the plant. They conduct outwardly the water and inorganic
-salts brought up from the roots by the vessels and tracheids;
-and they conduct inwardly toward the centre of the stem the
-food material manufactured in the leaves and brought down by
-the sieve cells. The medullary rays thus distribute the inorganic
-and organic food to the living cells of the plant, and
-they conduct the reserve food material to the storage cells, and,
-lastly, they function in certain plants as storage cells.</p>
-
-<h5>Occurrence</h5>
-
-<p>The form, size, wall structure, and the distribution of the
-medullary ray bundles, rays, and cells are best ascertained by<span class="pagenum" id="Page_139">[139]</span>
-studying: first, the cross-section of the plant; secondly, the
-radial section; and, thirdly, the tangential section.</p>
-
-<p>Students should be careful to distinguish between the medullary
-ray bundle, the medullary ray, and the medullary ray cell.
-In some plants the bundles are only one cell wide, but in other
-plants the medullary ray bundle is more than one cell wide,
-frequently several cells wide.</p>
-
-<h5 id="THE_MEDULLARY_RAY_BUNDLE">THE MEDULLARY RAY BUNDLE</h5>
-
-<p>The <span class="bold">medullary ray bundle</span> is made up of a great many medullary
-ray cells. These bundles (Plate 106, Fig. 5) are of variable
-length, height, and width. The bundles are isolated, and they
-occur among and separate the other cells of the plants in which
-they occur. Tangential sections show the medullary ray
-bundle in cross-section. Such sections are lens-shaped, and
-they show both the width and the height of the medullary ray
-bundle. The length of the medullary ray bundle is shown in
-cross-sections.</p>
-
-<h5 id="THE_MEDULLARY_RAY">THE MEDULLARY RAY</h5>
-
-<p>The <span class="bold">medullary ray</span> (Plate 47) is a term used to indicate
-that part of a medullary ray bundle which is seen in cross-sections
-and in radial sections. In cross-sections the length
-of the ray will be as great as the length of the bundle, and the
-width of the ray will be as great as the width of the medullary
-ray bundle at the point cut across. In longitudinal sections the
-medullary ray will differ in height according to the thickness of
-the bundle at the point cut.</p>
-
-<p>When the medullary rays extend from the centre of the stem
-to the middle bark, they are termed primary medullary rays;
-when they extend from the cambium circle to the middle bark,
-they are termed secondary medullary rays. As the plant grows,
-the diameter of the organ becomes greater and the number of
-medullary rays are increased. In each of these cases the medullary
-rays may be one or more than one cell wide, according to
-whether the medullary ray bundle is one or more than one cell
-wide. Even in the same plant the width of the medullary rays
-will vary if the bundle is more than one cell wide, according to
-width of the medullary ray bundle at the point cut across.</p>
-
-<p><span class="pagenum" id="Page_140">[140]</span></p>
-
-<div class="figcenter illowp46" id="plate47" style="max-width: 38.9375em;">
-  <img class="w100 p1" src="images/plate47.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 47</span><br />
-<span class="smcap">Radial Longitudinal Section of White Sandalwood</span> <br />(<i lang="la" xml:lang="la">Santalum album</i>, L.)
-
-<div class="blockquotc">
-<p class="noindent">1. Medullary ray.<br />
-2. Wood fibres and wood parenchyma.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_141">[141]</span></p>
-
-<p>On cross-section the medullary rays are seen to vary greatly.
-In many plants they are more or less straight radial lines, as
-in quassia (Plate 105, Fig. 2); while in other plants they form
-wavy lines where they bend or curve around the conducting
-cells, as in piper methysticum, kava-kava (Plate 48, Fig. A).</p>
-
-<p>In the study of powdered drugs the radial view of the medullary
-rays is most frequently seen.</p>
-
-<p>In a perfect radial section (Plate 107, Fig. 2) the medullary
-rays are seen as tiers of cells in contact throughout their long
-diameter, and they run at right angles to the long diameter of
-the other cells. This view of the rays shows the length and
-height of the medullary ray. In logwood the rays are often
-forty cells high. In powdered barks, woods (Plate 47), and
-woody roots the radial view of the medullary rays is frequently
-diagnostic.</p>
-
-<p>In guaiacum officianale wood the medullary rays are one
-cell wide on cross-section, and up to six cells high on the tangential
-section. In santalum album the rays are from one to
-three cells wide on cross-section, and up to six cells high on
-tangential section. In the greater number of plants the rays
-are more than one cell wide.</p>
-
-<h5 id="THE_MEDULLARY_RAY_CELL">THE MEDULLARY RAY CELL</h5>
-
-<p>The <span class="bold">medullary ray cell</span> (Plate 48, Fig. 1) is one of the individual
-cells making up the medullary ray bundle and the
-medullary ray.</p>
-
-<p>The cross-sections of the cells which are seen in tangential
-sections show the cells to be mostly circular in outline when
-they occur in the central portion of medullary ray bundles of
-more than two cells in width; but they are more irregular in
-outline when the medullary ray bundle is only one cell wide.
-Even the cells of the three or more cell-wide bundles have irregular,
-outlined cells at the ends of the bundle and on the sides
-in contact with the other tissues.</p>
-
-<p>The length and height of the medullary ray cell are shown
-in radial sections; while the width and length of the medullary
-ray cells are shown in cross-sections.</p>
-
-<p><span class="pagenum" id="Page_142">[142]</span></p>
-
-<h5 id="STRUCTURE_OF_CELLS">Structure of Cells</h5>
-
-<p>The structure of the individual cells forming the medullary
-rays differs greatly in different plants, but is more or less constant
-in structure in a given species.</p>
-
-<p>The medullary rays of the wood usually have strongly pitted
-side and end walls, while the medullary rays of most barks are
-not at all, or only slightly, pitted. In most plants the cells are
-of nearly uniform size. Frequently, however, the cells vary in
-size in a given ray, as shown in the cross-section of kava-kava.</p>
-
-<h5 id="ARRANGEMENT_OF_THE_CELLS_IN_A_RAY">Arrangement of the Cells in a Ray</h5>
-
-<p>The union of any two cells in a ray is also of importance.
-In quassia the medullary ray cells have oblique end walls, so
-that on cross-section the line of union between two cells is an
-oblique wall. In most plants the medullary ray cells have
-blunt or square or oblique end walls, so that the line of union
-is a straight line.</p>
-
-<p>In most plants the cells are much longer than broad, but the
-cells of sassafras bark are nearly as broad as long.</p>
-
-<p>The walls of the cortical medullary ray cells and the medullary
-rays of most roots and stems of herbs are composed of cellulose;
-while the walls of medullary ray cells occurring in woods
-are frequently lignified.</p>
-
-<p>There is a great variation in the character of the cell contents
-of medullary rays. In white pine bark (Plate 48, Fig.
-B1) are deposits of tannin; in quassia wood, starch; in canella
-alba, rosette crystals of calcium oxalate, etc.</p>
-
-<h4 id="LATEX_TUBES">LATEX TUBES</h4>
-
-<p>Living <span class="bold">latex tubes</span>, like sieve tubes, have a layer of protoplasm
-lining the walls, and, in addition, have numerous nuclei.
-In drug plants the nuclei are not distinguishable, but the protoplasm
-is always clearly discernible.</p>
-
-<p><span class="pagenum" id="Page_143">[143]</span></p>
-
-<div class="figcenter illowp65" id="plate48" style="max-width: 54.25em;">
-  <img class="w100 p1" src="images/plate48.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 48</span><br />
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Cross-section of kava-kava root (<i lang="la" xml:lang="la">Piper methysticum</i>, Forst., f.).<br />
-<span class="pad1">1. Unequal diameter medullary ray cells.</span><br />
-<span class="pad1">2. Vessels.</span><br />
-<span class="pad1">3. Wood parenchyma.</span><br />
-<span class="pad1">4. Wood fibres.</span><br />
-<em>B.</em> Cross-section of white pine bark (<i lang="la" xml:lang="la">Pinus strobus</i>, L.).<br />
-<span class="pad1">1. Wavy medullary rays with tannin.</span><br />
-<span class="pad1">2. Parenchyma cells.</span><br />
-<span class="pad1">3. Sieve cells.</span></p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_144">[144]</span></p>
-
-<p>Latex tubes function both as storage and as conducting cells.
-They, like the sieve tubes, contain proteid substances chiefly,
-yet frequently starch is found. The cells bordering the latex
-tubes absorb from them, as needed, the soluble food material.
-While our knowledge concerning the function of latex in some
-plants is meagre, still in other plants it is practically certain
-that the latex is composed of nutritive substances which are
-utilized by the plant as food. In certain other plants the latex
-appears to be used as a means of resisting insect attacks and as
-a protection against injury.</p>
-
-<p>There are two types of latex tubes common to plants, namely,
-latex cells and latex vessels. Latex tubes developing from a
-single cell do not differ materially from a latex tube originating
-from the fusion of several cells. In each case the latex tube
-branches to such an extent that it bears no resemblance to ordinary
-cells. It would seem that the ultimate branches are formed
-and develop in much the same manner as root hairs&mdash;that is,
-by a growing tip of the branch. A mature plant may therefore
-have latex tubes with almost numberless branches (Plate 50,
-Fig. 1) and be of very great length.</p>
-
-<p>The branches of latex tubes develop in such an irregular
-manner that it is possible to obtain a cross and a longitudinal
-section of the latex tubes by making a cross-section of stem.
-Such a section is shown in the drawing of the cross-section of
-the rhizome of black Indian hemp (Plate 49, Fig. B).</p>
-
-<p>The color of the latex in medicinal plants varies from a
-gray white in papaw (carica papaya), aromatic sumac, black
-Indian hemp, and bitter root, to white in the opium poppy,
-light orange in celandine, and deep orange in bloodroot (Plate
-50, Fig. 2). In each of these cases it is the latex which yields
-the important medicinal products.</p>
-
-<h4 id="PARENCHYMA">PARENCHYMA</h4>
-
-<p>The larger amount of plant tissue is composed of <span class="bold">parenchyma</span>
-cells. These cells vary from square to oblong, or they may be
-irregular and branched. The end walls are square or blunt,
-and the wall is composed of cellulose, with the exception of the
-wood parenchyma, which has lignified walls.</p>
-
-<p>There are seven characteristic types of parenchyma cells:
-(1) cortical parenchyma, (2) pith parenchyma, (3) wood parenchyma,
-(4) leaf parenchyma, (5) aquatic plant parenchyma,
-(6) endosperm parenchyma, (7) phloem parenchyma.</p>
-
-<p><span class="pagenum" id="Page_145">[145]</span></p>
-
-<div class="figcenter illowp54" id="plate49" style="max-width: 45.8125em;">
-  <img class="w100 p1" src="images/plate49.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 49</span>
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Cross-section of black Indian hemp (<i lang="la" xml:lang="la">Apocynum cannabinum</i>, L.).<br />
-<span class="pad1">1. Longitudinal section of a latex tube.</span><br />
-<span class="pad1">2. Cross-section of latex tube.</span><br />
-<span class="pad1">3. Parenchyma.</span><br />
-<em>B.</em> Cross-section of a part of black Indian hemp root.<br />
-<span class="pad1">4. Cross-section of a large latex tube.</span><br />
-<span class="pad1">5. Parenchyma.</span></p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_146">[146]</span></p>
-
-<div class="figcenter illowp53" id="plate50" style="max-width: 44.75em;">
-  <img class="w100 p1" src="images/plate50.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 50</span><br />
-<span class="smcap">Latex Vessels</span>
-
-<div class="blockquotc">
-<p>1. Radial-longitudinal section of dandelion root (<i lang="la" xml:lang="la">Taraxacum officinale</i>, Weber).<br />
-<span class="pad1">2.</span> Cross-section of sanguinaria root (<i lang="la" xml:lang="la">Sanguinaria canadensis</i>, L.).<br />
-<span class="pad1">3.</span> Cross-section of dandelion root.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_147">[147]</span></p>
-
-<p>Parenchyma cells, cortical, pith, aquatic plant, leaf, flower,
-and endosperm, conduct in all directions&mdash;upward, downward,
-and laterally. The direction of conduction depends upon the
-needs of the different cells forming the plant. The fluids pass
-from the cell with an abundance of cell sap to the cell with less
-cell sap. In this wall all cells are provided with food.</p>
-
-<p>Parenchyma cells conduct water absorbed by the roots and
-soluble carbohydrate material chiefly.</p>
-
-<p>The walls of all the different types of parenchyma cells are
-composed of cellulose with the exception of the wood parenchyma
-cells, the walls of which are lignified. The end walls of non-branched
-parenchyma cells and the cell terminations of branched
-cells are very blunt.</p>
-
-<h5 id="CORTICAL_PARENCHYMA">CORTICAL PARENCHYMA</h5>
-
-<p><span class="bold">Cortical parenchyma</span> (Plate 51) differs greatly in size, thickness
-of the walls, and arrangement. A study of the longitudinal
-sections of different parts of medicinal plants reveals the fact
-that the cortical parenchyma cells form superimposed layers
-in which the end walls are either parallel, in which case the
-arrangement resembles that of several rows of boxes standing
-on end, or the end walls of the cells alternate with each other,
-in which case the arrangement is similar to that of the arrangement
-of the bricks in a building.</p>
-
-<p>In certain plants the cortical parenchyma cells are long and
-narrow and rectangular in shape, while in other plants the cells,
-although still rectangular in outline, are very broad and approach
-the square form.</p>
-
-<p>All typical cortical parenchyma cells have uniformly thickened
-non-pitted walls. In most barks the parenchyma cells
-beneath the bark are elongated tangentially, but are very narrow
-radially. The cells are always arranged around intercellular
-spaces, which vary from triangular, quadrangular, etc., according
-to the number of cells bordering the intercellular space.</p>
-
-<h5 id="PITH_PARENCHYMA">PITH PARENCHYMA</h5>
-
-<p><span class="bold">Pith parenchyma</span> (Plate 52) differs from cortical parenchyma
-cells chiefly in the character of the walls, which are usually thicker
-and always pitted.</p>
-
-<p><span class="pagenum" id="Page_148">[148]</span></p>
-
-<div class="figcenter illowp46" id="plate51" style="max-width: 38.5625em;">
-  <img class="w100 p1" src="images/plate51.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 51</span><br />
-<span class="smcap">Parenchyma Cells</span>
-
-<div class="blockquotc">
-<p>1. Longitudinal section of the cortical parenchyma of celandine root (<i lang="la" xml:lang="la">Chelidonium majus</i>, L.) <br />
-<span class="pad1">2.</span> Cross-section of the cortical parenchyma of sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_149">[149]</span></p>
-
-<div class="figcenter illowp61" id="plate52" style="max-width: 51.4375em;">
-  <img class="w100 p1" src="images/plate52.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 52</span>
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Longitudinal section of the pith parenchyma of grindelia stem (<i lang="la" xml:lang="la">Grindelia squarrosa</i>, [Pursh] Dunal).<br />
-<span class="pad1">1. Cell cavity.</span><br />
-<span class="pad1">2. Cross-section of the porous end wall.</span><br />
-<span class="pad1">3. Surface view of the porous side wall.</span><br />
-<em>B.</em> Cross-section of the pith parenchyma of grindelia stem.<br />
-<span class="pad1">1. Cell cavity.</span><br />
-<span class="pad1">2. Porous walls.</span><br />
-<span class="pad1">3. Pitted end walls.</span></p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_150">[150]</span></p>
-
-<h5 id="LEAF_PARENCHYMA">LEAF PARENCHYMA</h5>
-
-<p>The <span class="bold">parenchyma cells</span> (Plate 109, Fig. 1) of leaves, of flower
-petals, and the parenchyma cells of some aquatic plants are
-branched; that is, each cell has more than two cell terminations.
-These cell terminations are frequently quite attenuated and
-usually very blunt. Such a cell structure provides for a greater
-amount of intercellular space and a maximum exposure of surface.
-This arrangement makes it possible for the parenchyma
-cells of the leaf to absorb more readily the enormous amount
-of carbon dioxide needed in the photosynthetic process.</p>
-
-<h5 id="AQUATIC_PLANT_PARENCHYMA">AQUATIC PLANT PARENCHYMA</h5>
-
-<p>The <span class="bold">parenchyma of aquatic plants</span> (Plate 59) has large
-intercellular spaces formed by the chains of cells.</p>
-
-<h5 id="WOOD_PARENCHYMA">WOOD PARENCHYMA</h5>
-
-<p><span class="bold">Wood parenchyma</span> (Plate 105, Fig. 3) <ins class="corr" id="tn150" title="Transcriber’s Note—“cells are the narrowest parenchyma cells occuring” changed to “cells are the narrowest parenchyma cells occurring”.">cells are the narrowest parenchyma cells occurring</ins>
-in the plant. Their walls are always lignified and strongly pitted,
-and in some cases the end walls common to two cells are obliquely
-placed.</p>
-
-<h5 id="PHLOEM_PARENCHYMA">PHLOEM PARENCHYMA</h5>
-
-<p><span class="bold">Phloem parenchyma</span> (Plate 100, Fig. 8) cells are usually
-associated with sieve cells. They are very long, narrow, and
-have thin, non-pitted walls. The thinness of the walls undoubtedly
-enables the cells to conduct diffusible food substance
-more quickly than the cortical parenchyma cells.</p>
-
-<h5 id="PALISADE_PARENCHYMA">PALISADE PARENCHYMA</h5>
-
-<p><span class="bold">Palisade parenchyma</span> of leaves is of the typical parenchyma
-shape and the end walls are placed nearly on a plane, even
-when more than one layer is present. The cells are very small,
-however, and the walls are very thin and non-pitted.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_151">[151]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_VI">CHAPTER VI<br />
-<span class="fs80">AERATING TISSUE</span></h3>
-</div>
-
-<p>The <span class="bold">aerating tissue</span> of the plant performs a threefold function:
-first, it permits the exchange of gases during photosynthesis;
-secondly, it permits the entrance of oxygen and the
-exit of carbon dioxide during respiration; and, thirdly, it permits
-the exit of the excess of water absorbed by the plant.</p>
-
-<p>The above functions are carried on by the stomata, the
-water-pores, the lenticels, and the intercellular spaces of the
-plant. The stoma functions as the chief channel for the passage
-of CO₂-laden air into the leaf and of oxygen-laden air from the
-leaf to the atmosphere. The stoma also functions as an organ
-of transpiration, since through the stoma a large part of the
-excess water of the plant passes off into the air.</p>
-
-<h4 id="WATER-PORES">WATER-PORES</h4>
-
-<p>In certain plants the primary epidermis is provided with
-openings resembling stomata, but unlike stomata the orifice
-remains open, and instead of being located on the upper or
-lower surface of the leaf, they are located on the margin of
-leaves immediately outward from the veins. Water is given
-off to the atmosphere from these openings. Such an opening
-is usually designated as a water-pore.</p>
-
-<h4 id="STOMATA">STOMATA</h4>
-
-<p>The chief external openings of the epidermis of leaves, of
-herbs, and of young wood stems are known as stomata. Surrounding
-the stoma are two cells known as guard cells.</p>
-
-<p><span class="bold">Guard cells</span> differ greatly in form, in size, in arrangement,
-in occurrence, in association, in abundance (Plates 53, 54, and
-55), and in color. The guard cells surrounding the stoma vary
-in form from circular to lens-shaped. In most leaves the outline
-of the guard cells is rounded or has a curved outline; but in a
-few cases the guard cells have angled outlines.</p>
-
-<p><span class="pagenum" id="Page_152">[152]</span></p>
-
-<div class="figcenter illowp51" id="plate53" style="max-width: 43.1875em;">
-  <img class="w100 p1" src="images/plate53.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 53</span>
-
-<div class="blockquotc">
-<p>1. Stoma and surrounding cells of aconite stem (<i lang="la" xml:lang="la">Aconitum napellus</i>, L.). <br />
-<span class="pad1">2.</span> Stoma and angled striated walled surrounding cells of peppermint stem (<i lang="la" xml:lang="la">Mentha piperita</i>, L.). <br />
-<span class="pad1">3.</span> Stoma and elongated surrounding cells of lobelia stem (<i lang="la" xml:lang="la">Lobelia inflata</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_153">[153]</span></p>
-
-<div class="figcenter illowp55" id="plate54" style="max-width: 45.875em;">
-  <img class="w100 p1" src="images/plate54.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 54</span><br />
-<span class="smcap">Types of Stoma</span>
-
-<div class="blockquotc">
-<p>1. Under epidermis of short buchu (<i lang="la" xml:lang="la">Barosma betulina</i>, [Berg.] Bartling and Wendl., f.) showing stoma and deposits of hesperidin.<br />
-<span class="pad1">2.</span> Under epidermis of Alexandria senna (<i lang="la" xml:lang="la">Cassia acutifolia</i>, Delile) showing stoma and thick-angled walled surrounding cells.<br />
-<span class="pad1">3.</span> Upper epidermis of eucalyptus leaf (<i lang="la" xml:lang="la">Eucalyptus globulus</i>, Labill.) showing sunken stoma and slightly beaded walled surrounding cells.<br />
-<span class="pad1">4.</span> Under epidermis of belladonna leaf (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.) showing stoma and wavy, striated, walled epidermal cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_154">[154]</span></p>
-
-<p>The <span class="bold">arrangement of the surrounding cells</span> of the stoma
-is one of the most important characteristics of the different
-leaves. As a rule the number of surrounding cells about a
-stoma is constant for a given species. In senna leaves (Plate
-54, Fig. 2) there are normally two surrounding cells about
-each guard cell, while in coca there are four (Plate 55, Fig. 1).
-In senna the long diameter of the surrounding cells is parallel to
-the long diameter of the guard cells; but in coca the long diameter
-of two surrounding cells is at right angles to the long diameter of
-the guard cells, while two cells are parallel to the long diameter
-of the guard cells.</p>
-
-<p>In most leaves there are more than two cells around the
-guard cells.</p>
-
-<p>The form and size of the surrounding cells must always be
-considered. In most leaves they are variable in size and form.</p>
-
-<p>Guard cells occur first, even with the surface of the leaf (Plate
-56, Fig. A); secondly, above the surface of the leaf (Plate 56,
-Fig. B); and, thirdly, below the surface of the leaf. (Plate 56,
-Fig. C). Only one of the above types occurs in a given species
-of plant. That is, plants with stomata above the surface of the
-leaf do not have stomata on a level with or below the leaf
-surface.</p>
-
-<p>The number of stomata on a given surface of a different leaf
-varies considerably.</p>
-
-<p>In many of the medicinal leaves stomata occur only on the
-under surface of the leaf. In other leaves stomata occur on both
-surfaces of the leaf; but in such cases there are a greater number
-on the under surface.</p>
-
-<p>In certain leaves the long diameter of the guard cells is
-parallel to the length of the leaf; in other cases the long diameter
-of the stoma is arranged at right angles to the length of the leaf.</p>
-
-<p>In other leaves the arrangement is still more irregular, the
-guard cells assuming all sorts of positions in relation to the
-length of the leaf.</p>
-
-<p><span class="pagenum" id="Page_155">[155]</span></p>
-
-<div class="figcenter illowp54" id="plate55" style="max-width: 45.1875em;">
-  <img class="w100 p1" src="images/plate55.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 55</span><br />
-<span class="smcap">Leaf Epidermi with Stoma</span>
-
-<div class="blockquotc">
-<p>1. Under epidermis of coca leaf (<i lang="la" xml:lang="la">Erythroxylon coca</i>, Lam.) with stoma on a level with the surface.<br />
-<span class="pad1">2.</span> Under epidermis of false buchu (<i lang="la" xml:lang="la">Marrubium peregrinum</i>, L.) with stoma below the level of the surface.<br />
-<span class="pad1">3.</span> <ins class="corr" id="tn155" title="Transcriber’s Note—“Upper epidermis of deer tongue Trilisia odoratissima” changed to “Upper epidermis of deer tongue Trilisa odoratissima”.">Upper epidermis of deer tongue (<i lang="la" xml:lang="la">Trilisa odoratissima</i></ins>,
-[Walt.] Cass.) with stoma above the leaf surface.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_156">[156]</span></p>
-
-<div class="figcenter illowp55" id="plate56" style="max-width: 46.25em;">
-  <img class="w100 p1" src="images/plate56.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 56</span><br />
-
-<div class="blockquotc">
-<p><em>A.</em> Cross-section of belladonna leaf (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.). 1, Epidermal cells; 2, Guard cells even with the leaf surface; 3, Surrounding cells; 4, Air space below the guard cells; 5, Palisade cells; 6, Mesophyll cells. <br />
-<span class="pad1"><em>B.</em></span> Cross-section of deer tongue leaf, 1. Epidermal cells; 2, Guard cells above the surface of the leaf; 3, Surrounding cells; 4, Air space below the guard cells; 5, Hypodermal cells. <br />
-<span class="pad1"><em>C.</em></span> Cross-section of white pine leaf (<i lang="la" xml:lang="la">Pinus strobus</i>, L.). 1, Epidermal and hypodermal cells; 2, Guard cells below the leaf surface; 3, Surrounding cells; 4, Air space below the guard cells; 5, Parenchyma cells with projecting inner walls.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_157">[157]</span></p>
-
-<p>The <span class="bold">relation of the stoma to surrounding cells</span> is best shown
-in cross-sections of the leaf. In powders the relationship of
-the stoma to the surrounding cells is, however, readily ascertained.
-If the guard cells come in focus first, they are above
-the surface; if the guard cells and the surrounding cells come
-in focus at the same time, the stomata are even with the surface;
-if the stomata come in focus after the surrounding cells,
-they are below the surface of the leaf. The relationship of
-the stoma to the surrounding cells should always be ascertained,
-not only in cross-sections of the leaf, but also in powders.</p>
-
-<p>There is the greatest possible variation in the size of guard
-cells. This fact must always be kept in mind when studying
-leaves. This variation in the size of the guard cells is clearly
-illustrated by coca, senna, and by deer’s-tongue. In coca the
-stomata are very small; in senna they are larger; while in
-deer’s-tongue the stomata are very large.</p>
-
-<p>The width and length of the stoma or opening between the
-guard cells are of a character which must not be overlooked.
-Generally speaking, those leaves which have large guard cells
-will have correspondingly large stomata.</p>
-
-<p>The guard cells usually contain chloroplasts showing various
-stages of decomposition.</p>
-
-<p>In bay-rum leaf the guard cells are of a bright reddish-brown
-color, but in most leaves the guard cells are colorless.</p>
-
-<h4 id="LENTICELS">LENTICELS</h4>
-
-<p><span class="bold">Lenticels</span> are small openings occurring in the bark of plants.
-The lenticels bear the same relationship to the stem that the
-stomata do to the leaves. Lenticels, like stomata, have a threefold
-function&mdash;namely, exchange of gases in photosynthesis,
-in respiration, and the giving off of water.</p>
-
-<p>Lenticels are macroscopically as well as microscopically
-important. When unmagnified the lenticels are circular, lens-shaped,
-or irregular in outline. They are arranged in parallel
-longitudinal lines or parallel transverse lines, or they are irregularly
-scattered. The latter is the usual arrangement. In
-most cases they are elevated slightly above the surface of the
-bark. In root barks particularly the lenticels stand out prominently
-from the surface of the bark and in many cases appear
-stalked.</p>
-
-<p>The color of the lenticels differs greatly in the different<span class="pagenum" id="Page_158">[158]</span>
-plants. In acer spicatium they are brown; in witch-hazel they
-are gray; in xanthoxylium they are yellowish; and lastly, the
-number of lenticels occurring in a given surface of the bark
-should always be considered.</p>
-
-<p>On cross-sections the lenticel (Plate 57, Fig. 2) is seen to
-have a central depressed portion made up of loosely arranged
-cells. Bordering the cavity are typical cork cells. The cork
-cells immediately surrounding the lenticels are usually darker
-in color, and many of the cells are partly broken down.</p>
-
-<p>The size of lenticels will vary according to the type of the
-lenticel. In studying sections more attention should be paid
-to the character of the cells forming the lenticels than to the
-size of the lenticel.</p>
-
-<p>On cross-section the intercellular spaces (Plate 58) are triangular,
-quadrangular, or irregular. The spaces between equal
-diameter parenchyma cells is triangular if three cells surround
-the space, and quadrangular if four cells surround the space,
-etc. These spaces are in direct contact with similar spaces that
-traverse the tissue at right angles to its long axis.</p>
-
-<p>The branched mesophyll cells of the leaf and aquatic plant
-parenchyma (Plate 59) are arranged around irregular cavities.
-In leaves and aquatic plants these spaces run parallel to the
-long axis of the organ.</p>
-
-<p>In each of the above cases the cavity is formed by the separation
-of the cell walls. There is still another type of irregular
-cavities which is formed by the dissolution or tearing apart of
-the cell walls. Such cavities are found in the stems and roots
-of many herbs.</p>
-
-<p>The pith cells in the stems of many herbs become torn
-apart during the growth of the stem, with the result that large
-irregular cavities are formed. These cavities are usually filled
-with circulatory air.</p>
-
-<p>In the stems of conium, cicuta, angelica, and other larger
-herbaceous stems the pith separates into layers. When a
-longitudinal section is made of such a stem it is seen to be composed
-of alternating air spaces and masses of pith parenchyma.</p>
-
-<p>The intercellular spaces are very large in leaves where
-enormous quantities of carbon dioxide are vitalized in photosynthesis.</p>
-
-<p><span class="pagenum" id="Page_159">[159]</span></p>
-
-<div class="figcenter illowp100" id="plate57" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate57.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 57</span><br />
-
-<span class="smcap">Cross-Section of Elder Bark</span> (<i lang="la" xml:lang="la">Sambucus canadensis</i>, L.). 1. Periderm. 2. Lenticel. 3. Phellogen.</div>
-</div>
-
-<p><span class="pagenum" id="Page_160">[160]</span></p>
-
-<div class="figcenter illowp52" id="plate58" style="max-width: 43.9375em;">
-  <img class="w100 p1" src="images/plate58.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 58</span><br />
-<span class="smcap">Intercellular Air Spaces</span>
-
-<div class="blockquotc">
-<p><em>A.</em> Cross-section of uva-ursi leaf (<i lang="la" xml:lang="la">Arctostaphylos uva-ursi</i>, [L.] Spreng.).<br />
-<span class="pad2">1.</span> Irregular intercellular air spaces.<br />
-<span class="pad1"><em>B.</em></span> Cross-section of the cortical parenchyma of sarsaparilla root (<i lang="la" xml:lang="la">Smilax
-officinalis</i>, Kunth). 1, Triangular intercellular spaces; 2, Quadrangular intercellular
-air spaces; 3, Pentagular intercellular air spaces.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_161">[161]</span></p>
-
-<div class="figcenter illowp52" id="plate59" style="max-width: 43.375em;">
-  <img class="w100 p1" src="images/plate59.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 59</span><br />
-<span class="smcap">Irregular Intercellular Air Spaces</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Skunk-cabbage (<i lang="la" xml:lang="la">Symplocarpus fœtidus</i>, [L.] Nutt.)<br />
-2. Calamus rhizome (<i lang="la" xml:lang="la">Acorus calamus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_162">[162]</span></p>
-
-<p>In the rhizome of calamus and other aquatic plants the
-intercellular spaces are very large. The cells of these plants
-are arranged in the form of branching chains of cells which thus
-provide for large intercellular spaces.</p>
-
-<p>The cells of the middle layer of flower petals, like the mesophyll
-of leaves, is loosely arranged owing to the peculiar branching
-form of the cells.</p>
-
-<p>Seeds and fruits contain, as a rule, few or no intercellular
-spaces.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_163">[163]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_VII">CHAPTER VII<br />
-<span class="fs80">SYNTHETIC TISSUE</span></h3>
-</div>
-
-<p>Under synthetic tissue are grouped all tissues and cells which
-form substances or compounds other than protoplasm. Such
-compounds are stored either in special cavities or in the cells
-of the plant, as the glandular hairs; internal secreting cavities
-of barks, stems, leaves, fruits, seeds, and flowers; photosynthetic
-cells or cells with chlorophyll, and the parenchymatic
-cells which form starch, sugar, fats, alkaloids, etc.</p>
-
-<h4 id="PHOTOSYNTHETIC_TISSUE">PHOTOSYNTHETIC TISSUE</h4>
-
-<p>The most important non-glandular synthetic tissue is the
-photosynthetic tissue, which is composed of the chlorophyll-bearing
-cells of the plant. These are the so-called green cells
-of leaves, of stems of herbs, of young woody stems, and in the
-older woody stems of plants like wild cherry, birch, etc. The
-greater part of the tissue of leaves is composed of chlorophyll-bearing
-cells.</p>
-
-<p>Leaves collectively constitute the greatest synthetic manufacturing
-plant in the world, because the green cells of the leaf
-produce most of the food of men and animals. The two compounds
-utilized in the manufacture of food are carbon dioxide
-(CO₂) and water (H₂O). These two compounds are combined
-by chlorophyll through the agency of light into starch. Chemically
-this reaction may be expressed as follows:</p>
-
-<p class="pfs90">6CO₂ + 5H₂O = 2C₆H₁₀O₅ + 6O₂.</p>
-
-<p>During the day a large quantity of starch is formed. At
-night through the action of a ferment the excess of starch remaining
-in the leaf is converted into sugar <span class="fs90">(C₆H₁₂O₆) - C₆H₁₀O₅ +
-H₂O = C₆H₁₂O₆</span>. In this form it is distributed to the living
-cells of the plant. The presence or absence of starch in leaves
-is easily ascertained by placing the leaf in hot alcohol to remove<span class="pagenum" id="Page_164">[164]</span>
-the chlorophyll, and by adding Lugol’s solution. If starch is
-present, the contents of the cells will become bluish black; but
-if no starch is present, the cells remain colorless.</p>
-
-<h4 id="GLANDULAR_TISSUE">GLANDULAR TISSUE</h4>
-
-<p>The <span class="bold">glandular tissue</span> of the plant is divided into two groups,
-according to where it occurs. These groups are, first, <span class="bold">external</span>
-glandular tissue, and secondly, <span class="bold">internal</span> glandular tissue. The
-most important external glandular tissue is composed of the
-glandular hairs. These are divided into two groups: first,
-<span class="bold">unicellular</span>; and secondly, <span class="bold">multicellular</span> glandular hairs.</p>
-
-<h5 id="UNICELLULAR_GLANDULAR_HAIRS">UNICELLULAR GLANDULAR HAIRS</h5>
-
-<p>The <span class="bold">unicellular glandular hairs</span> are either sessile or stalked.</p>
-
-<p><span class="bold">Sessile unicellular hairs</span> occur in digitalis leaves.</p>
-
-<p><span class="bold">Stalked unicellular hairs</span> of digitalis are shown on Plate 60,
-Fig. 2.</p>
-
-<p><span class="bold">Unicellular uniseriate stalked glandular hairs</span> occur on the
-stems of the common house geranium (Plate 61, Fig. 2), on the
-leaves of butternut, the leaves and stems of marrubium peregrinum
-(Plate 98, Fig. 5), and in arnica flowers. The stalk varies
-from two to ten cells; in eriodictyon the cells vary from four
-to eight cells.</p>
-
-<p>Unicellular multiseriate stalked glandular hairs are not of
-common occurrence.</p>
-
-<h5>MULTICELLULAR GLANDULAR HAIRS</h5>
-
-<p><span class="bold">Multicellular glandular hairs</span> are divided into two groups:
-first, sessile; and secondly, stalked hairs.</p>
-
-<p>Multicellular sessile glandular hairs occur on the leaves of
-peppermint (Plate 60, Fig. 3), horehound (Plate 97, Fig. 7),
-and in hops (Plate 60, Fig. 4). In each of these hairs there are
-eight secretion cells.</p>
-
-<p><span class="bold">Stalked glandular hairs</span> are divided into two groups: first,
-uniseriate stalked; and secondly, multiseriate stalked glandular
-hairs.</p>
-
-<p><span class="bold">Multicellular uniseriate stalked glandular hairs</span> occur on
-the leaves of tobacco (Plate 61, Fig. 4), belladonna (Plate 61, Fig. 1),
-and digitalis (Plate 60, Fig. 2), and of the fruit of rhus
-glabra.</p>
-
-<p><span class="pagenum" id="Page_165">[165]</span></p>
-
-<div class="figcenter illowp57" id="plate60" style="max-width: 48.0625em;">
-  <img class="w100" src="images/plate60.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 60</span><br />
-<span class="smcap">Glandular Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Kamala (<i lang="la" xml:lang="la">Mallotus philippinensis</i>, [Lam.] [Muell.] Arg.).<br />
-2. Digitalis leaf (<i lang="la" xml:lang="la">Digitalis purpurea</i>, L.).<br />
-3. Peppermint leaf (<i lang="la" xml:lang="la">Mentha piperita</i>, L.).<br />
-4. Lupulin.<br />
-5. Cannabis indica leaf (<i lang="la" xml:lang="la">Cannabis saliva</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_166">[166]</span></p>
-
-<p><span class="bold">Multicellular multiseriate stalked glandular hairs</span> occur on
-the stems and leaves of cannabis indica (Plate 60, Fig. 5).</p>
-
-<p>In the glandular hair of kamala (Plate 60, Fig. 1) the number
-of secretion cells is variable and papillate in form, and the
-cuticle is separated from the secretion cells.</p>
-
-<p>In the glandular hair of hops the outer wall or cuticle is torn
-away from the secretion cells, and the cavity thus formed serves
-as a storage cavity. This distended cuticle of the hops shows
-the outline of the cells from which it was separated.</p>
-
-<p>In the glandular hairs of the mints the secreted products
-(volatile oils) are stored between the secretion cells and the outer
-detached cuticle. This cuticle is elastic, and it becomes greatly
-distended as the volatile oil increases in amount.</p>
-
-<p>In many of the so-called glandular hairs, tobacco, belladonna
-geranium, etc., the synthetic products are retained in the glandular
-cells, there being no special cavity for their storage.</p>
-
-<p>These hairs usually contain an abundance of chlorophyll.</p>
-
-<p>The division wall of multicellular glandular hairs may be
-vertical, as in the two-celled hair of digitalis (Plate 60, Fig. 2);
-as in horehound (Plate 97, Fig. 6), and as in peppermint (Plate
-60, Fig. 3); in this case there are eight cells, and they form a
-more or less flat plate of cells.</p>
-
-<p>In other hairs the division wall is horizontal; this produces
-a chain of superimposed secreting cells, as in some of the glandular
-hairs of belladonna leaf (Plate 61, Fig. 1), etc.</p>
-
-<p>In other hairs the division walls are both vertical and horizontal,
-as in tobacco (Plate 61, Fig. 4), henbane (Plate 61, Fig.
-3), belladonna (Plate 61, Fig. 1).</p>
-
-<p>Other characters to be kept in mind in studying glandular
-hairs are the following: Color of cell contents; size of the
-cells, whether uniform or variable; character of wall, whether
-smooth or rough.</p>
-
-<h4 id="SECRETION_CAVITIES">SECRETION CAVITIES</h4>
-
-<p><span class="bold">Secretion cavities</span> are divided into three groups, according
-to the nature of the origin of the cavity: first, schizogenous
-cavities, which originate by a separation of the walls of the
-secretion cells; secondly, lysigenous cavities, which arise by the
-dissolution of the walls of centrally located secretion cells; and
-thirdly, schizo-lysigenous cavities, which originate schizogenously,
-but later become lysigenous owing to the dissolution of
-the outer layers of the secretion cells.</p>
-
-<p><span class="pagenum" id="Page_167">[167]</span></p>
-
-<div class="figcenter illowp54" id="plate61" style="max-width: 137.5em;">
-  <img class="w100 p1" src="images/plate61.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 61</span><br />
-<span class="smcap">Stalked Glandular Hairs</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Belladonna leaf (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.).<br />
-2. Geranium stem (<i lang="la" xml:lang="la">Geranium maculatum</i>, L.).<br />
-3. Henbane leaf (<i lang="la" xml:lang="la">Hyoscyamus niger</i>, L.).<br />
-4. Tobacco leaf (<i lang="la" xml:lang="la">Nicotiana tabacum</i>, L.).</p></div></div>
-</div>
-
-<p><span class="pagenum" id="Page_168">[168]</span></p>
-
-<h5 id="SCHIZOGENOUS_CAVITIES">SCHIZOGENOUS CAVITIES</h5>
-
-<p><span class="bold">Schizogenous cavities</span> occur in white pine bark (Plate 62,
-Fig. B). The cells lining the cavity are mostly tangentially elongated,
-and the wall extends into the cavity in the form of a
-papillate projection. Immediately back from these cells are
-two or three layers of cells which resemble cortical parenchyma
-cells, except that they are smaller and their walls are thinner.</p>
-
-<p>In white pine bark there is a single layer of thin-walled
-cells lining the cavity. Immediately surrounding the secretion
-cells is a single layer of thick-walled fibrous cells.</p>
-
-<p>In klip buchu (Plate 63, Fig. B), as in white pine leaf (Plate
-64, Fig. B), there is a single layer of thin-walled secretion cells
-which are surrounded on three sides with parenchyma cells and
-on the outer side by epidermal cells.</p>
-
-<h5 id="LYSIGENOUS_CAVITIES">LYSIGENOUS CAVITIES</h5>
-
-<p><span class="bold">Lysigenous cavities</span> occur on the rind of citrus fruits&mdash;bitter
-and sweet orange, lemon, grapefruit, lime, etc., and in the leaves
-of garden rue, etc.</p>
-
-<p>In bitter orange peel, (Plate 64, Fig. A) the cavity is very
-large, and the cells bordering the cavity are broken and partially
-dissolved. The entire cells back of these are white, thin-walled,
-tangentially elongated cells. There is a great variation in the
-size of these cavities, the smaller cavities being the recently
-formed cavities.</p>
-
-<h5 id="SCHIZO-LYSIGENOUS_CAVITIES">SCHIZO-LYSIGENOUS CAVITIES</h5>
-
-<p><span class="bold">Schizo-lysigenous</span> cavities are formed in white pine bark
-and many other plants owing to the increase in diameter of the
-stem. In such cases the walls of the secreting cells break down.
-The resulting cavity resembles lysigenous cavities.</p>
-
-<p><span class="bold">Unicellular secretion cavities</span> occur in ginger, aloe, calamus,
-and in canella alba barb.</p>
-
-<p><span class="pagenum" id="Page_169">[169]</span></p>
-
-<div class="figcenter illowp49" id="plate62" style="max-width: 130.625em;">
-  <img class="w100 p1" src="images/plate62.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 62</span>
-
-<div class="blockquotc">
-<p><em>A.</em> Cross-section of calamus rhizome (<i lang="la" xml:lang="la">Acorus calamus</i>,
-L.). 1, Intercellular space; 2, Parenchyma cells; 3, Secretion
-cavity. <em>B.</em> Cross-section of white pine bark (<i lang="la" xml:lang="la">Pinus
-strobus</i>, L.). 1, Parenchyma; 2, Secretion cavity; 3, Secretion
-cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_170">[170]</span></p>
-
-<div class="figcenter illowp57" id="plate63" style="max-width: 129.9375em;">
-  <img class="w100 p1" src="images/plate63.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 63</span>
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Cross-section of a portion of canella alba bark (<i lang="la" xml:lang="la">Canella alba</i>, Murr.).<br />
-<span class="pad1">1.</span> Excretion cavity.<br />
-<em>B.</em> Cross-section of a portion of klip buchu leaf.<br />
-<span class="pad1">1.</span> Epidermal cells.<br />
-<span class="pad1">2.</span> Secretion cavity.<br />
-<span class="pad1">3.</span> Secretion cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_171">[171]</span></p>
-
-<div class="figcenter illowp47" id="plate64" style="max-width: 129.9375em;">
-  <img class="w100 p1" src="images/plate64.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 64</span><br />
-
-<div class="blockquotc">
-<p><em>A.</em> Cross-section of bitter orange peel (<i lang="la" xml:lang="la">Citrus
-aurantium</i>, <i lang="la" xml:lang="la">amara</i>, L.). 1, Internal secretion cavity formed
-by the dissolution of the walls of the central secreting cells; 2,
-Secretion cells. <em>B.</em> Cross-section of white pine leaf (<i lang="la" xml:lang="la">Pinus
-strobus</i>, L.). 1, Epidermal and hypodermal cells; 2, <ins class="corr" id="tn171" title="Transcriber’s Note—“Parenchyma cells with protuding” changed to “Parenchyma cells with protruding”.">Parenchyma cells with protruding</ins>
-inner walls; 3, Endodermis; 4, Secretion
-cavity; 5, Secretion cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_172">[172]</span></p>
-
-<p>In calamus (Plate 62, Fig. A) the cavity is larger than the
-surrounding cells; it is rounded in outline, and it contains
-oleoresin. These cavities are in contact with the ordinary
-parenchyma cells, from which they are easily distinguished by
-their larger size and rounded form.</p>
-
-<p>The <span class="bold">unicellular oil cavity</span> of canella alba (Plate 63, Fig. A)
-is rounded or oval in cross-section and is many times larger
-than the surrounding cells. The wall, which is very thick, is
-of a yellowish color.</p>
-
-<p>Secretion cavities vary greatly in form, according to the
-part of the plant in which they are found. In flower petals and
-leaves they are spherical; in barks they are usually elliptical;
-in umbelliferous fruits they are elongated and tube-like.</p>
-
-<p>Mucilage cavities are not of common occurrence in medicinal
-plants. They occur, however, in the stem and root bark of
-sassafras, the stem bark of slippery elm, the root of althea, etc.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_173">[173]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_VIII">CHAPTER VIII<br />
-<span class="fs80">STORAGE TISSUE</span></h3>
-</div>
-
-<p>Most drug plants contain storage products because they
-are collected at a period of the year when the plant is storing,
-or has stored, reserve products. These products are stored
-in a number of characteristic ways and in different types of
-tissue.</p>
-
-<p>The most important of the different types of storage tissue
-that occurs in plants are the storage cells, the storage cavities,
-and the storage walls.</p>
-
-<h4 id="STORAGE_CELLS">STORAGE CELLS</h4>
-
-<p>Several different types of cells function as storage tissue.
-These cells, which are given in the order of their importance,
-are parenchyma, crystal cells, medullary rays, stone cells, wood
-fibres, bast fibres, and epidermal and hypodermal cells.</p>
-
-<h5>CORTICAL PARENCHYMA</h5>
-
-<p><span class="bold">Cortical parenchyma</span> of biennial rhizomes, bulbs, roots,
-and the parenchyma of the endosperm of seeds store most of
-the reserve economic food products of the higher plants.</p>
-
-<p><span class="bold">Pith parenchyma</span> of sarsaparilla root (Plate 65, Fig. 4) and
-the pith parenchyma of the rhizome of memspermun, like the
-pith parenchyma of most plants, function as storage cells.</p>
-
-<h5>WOOD PARENCHYMA</h5>
-
-<p><span class="bold">Wood parenchyma</span>, particularly of the older wood, function
-as storage tissue. The wood parenchyma of quassia, like the
-wood parenchyma of most woods, contain stored products. In
-some cases the wood parenchyma contain starch, in others crystals,
-and in others coloring matter, etc.</p>
-
-<p><span class="pagenum" id="Page_174">[174]</span></p>
-
-<div class="figcenter illowp52" id="plate65" style="max-width: 131.6875em;">
-  <img class="w100 p1" src="images/plate65.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 65</span>
-
-<div class="blockquotc">
-<p>1. Stone cells with starch of Ceylon cinnamon (<i lang="la" xml:lang="la">Cinnamomum
-ceylanicum</i>, Nees.). 2. Stone cells with solitary crystals of
-calumba root (<i lang="la" xml:lang="la">Jateorhiza palmata</i>, [Lam.] Miers). 3. Parenchyma
-cells, with starch of cascarilla bark (<i lang="la" xml:lang="la">Croton eluteria</i>,
-[L.] Benn.). 4. Cortical parenchyma with starch of sarsaparilla
-root (<i lang="la" xml:lang="la">Smilax officinalis</i>, Kunth). 5. Cortical parenchyma,
-with starch of leptandra rhizome (<i lang="la" xml:lang="la">Leptandra virginica</i>, [L.]
-Nutt.). 6. Crystal cells, with solitary crystals of quebracho bark
-(Schlechtendal). 7. Bast fibre of blackberry root with starch
-(<i lang="la" xml:lang="la">Rubus cuneifolius</i>, Pursh.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_175">[175]</span></p>
-
-<div class="figcenter illowp53" id="plate66" style="max-width: 131.6875em;">
-  <img class="w100 p1" src="images/plate66.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 66</span><br />
-<span class="smcap">Mucilage and Resin</span>
-
-<div class="blockquotc">
-<p>1. Cross-section of elm bark (<i lang="la" xml:lang="la">Ulmus fulva</i>, Michaux) showing two cavities filled with partially swollen mucilage.<br />
-<span class="pad1">2.</span> Mucilage mass from sassafras stem bark (<i lang="la" xml:lang="la">Sassafras variifolium</i>, L.).<br />
-<span class="pad1">3.</span> Mucilage mass from elm bark.<br />
-<span class="pad1">4.</span> Resin mass from white pine bark (<i lang="la" xml:lang="la">Pinus strobus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_176">[176]</span></p>
-
-<p>In many plants, however, the parenchyma cells contain
-crystals. The parenchyma cells of rhubarb contain rosette
-crystals, while the parenchyma cells of the cortex of sarsaparilla
-and false unicorn root contain bundles of raphides. In every case
-observed the raphides are surrounded by mucilage. This is true
-of squills, sarsaparilla, false unicorn, etc. When cells with
-raphides and mucilage are mounted in a mixture of alcohol,
-glycerine, and water, the mucilage first swells and finally disappears.</p>
-
-<h4 id="STORAGE_CAVITIES">STORAGE CAVITIES</h4>
-
-<p>Particular attention should be given to <span class="bold">storage cavities</span>
-whenever they occur in plants, for the reason that they are
-usually filled with storage products, and for the added reason
-that storage cavities are not common to all plants. Storage
-cavities occur in roots, stems, leaves, flowers, fruits, and seeds.</p>
-
-<h5 id="CRYSTAL_CAVITIES">CRYSTAL CAVITIES</h5>
-
-<p>Characteristic <span class="bold">crystal cavities</span> occur in many plants. Such
-a cavity containing a bundle of raphides is shown in the cross-section
-of skunk cabbage leaf (Plate 67).</p>
-
-<h5 id="MUCILAGE_CAVITIES">SECRETION CAVITIES</h5>
-
-<p>In white pine bark there are a great number of secretion
-cavities which are partially or completely filled with oleoresin.
-In the cross-sections of white pine bark the secretion cavities
-are very conspicuous, and they vary greatly in size. This
-variation is due, first, to the age of the cavity, the more recently
-formed cavities being smaller; and secondly, to the
-nature of the section, which will be longer in longitudinal section,
-which will be through the length of the secretion cavity, and
-shorter on transverse section. Such a section shows the width
-of the secretion cavity.</p>
-
-<p>Characteristic <span class="bold">mucilage cavities</span> occur in sassafras root, stem
-bark, elm bark (Plate 66, Fig. 1), marshmallow root, etc.
-These cavities form a conspicuous feature of the cross-section
-of these plants. The presence or absence of mucilage cavities
-in a bark should be carefully noted.</p>
-
-<h5 id="LATEX_CAVITIES">LATEX CAVITIES</h5>
-
-<p>The <span class="bold">latex tube cavities</span> are characteristic in the plants in
-which they occur. These cavities as explained under latex
-tubes are very irregular in outline.</p>
-
-<p><span class="pagenum" id="Page_177">[177]</span></p>
-
-<div class="figcenter illowp50" id="plate67" style="max-width: 126.8125em;">
-  <img class="w100 p1" src="images/plate67.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 67</span><br />
-<span class="smcap">Cross-Section of Skunk-cabbage Leaf</span> (<i lang="la" xml:lang="la">Symplocarpus fœtidus</i>,<br />
-[L.] Nutt.)
-
-<div class="blockquotc">
-<p>1. Crystal cavity.<br />
-<span class="pad1">2.</span> Bundle of raphides.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_178">[178]</span></p>
-
-<h5 id="OIL_CAVITY">OIL CAVITY</h5>
-
-<p>Canella alba contains an <span class="bold">oil cavity</span> resembling in form the
-mucilage cavity of elm bark.</p>
-
-<p><span class="bold">Secretion cavities</span> occur in most of the umbelliferous fruits.
-For each fruit there is a more or less constant number of cavities.
-Anise has twenty or more, fennel usually has six cavities, and
-parsley has six cavities.</p>
-
-<p>In poison hemlock fruits there are no secretion cavities. In
-certain cases, however, the number of secretion cavities can
-be made to vary. This was proved by the author in the case
-of celery seed. He found that cultivated celery seed, from
-which stalks are grown, contains six oil cavities (Plate 122,
-Fig. 2), while wild celery seed (Plate 102, Fig. 1), grown for its
-medicinal value, always contains more than six cavities. Most
-of the wild celery seeds contain twelve cavities.</p>
-
-<p>Many leaves contain cavities for storing secreted products.
-Such storage cavities occur in fragrant goldenrod, buchu, thyme,
-savary, etc.</p>
-
-<p>The leaves in which such cavities occur are designated as
-pellucid-punctate leaves. Such leaves will, when held between
-the eye and the source of light, exhibit numerous rounded
-translucent spots, or storage cavities.</p>
-
-<h5 id="GLANDULAR_HAIRS">GLANDULAR HAIRS</h5>
-
-<p>The <span class="bold">glandular hair of peppermint</span> (Plate 60, Fig. 3) and other
-mints consists of eight secretion cells, arranged around a central
-cavity and an outer wall which is free from the secretion cells.
-This outer wall becomes greatly distended when the secretion
-cells are active, and the space between the secretion cells and
-the wall serves as the storage place for the oil. When the mints
-are collected and dried, the oil remains in the storage cavity
-for a long time.</p>
-
-<h5>STONE CELLS</h5>
-
-<p>The <span class="bold">stone cells</span> of the different cinnamons (Plate 65, Fig. 1)
-store starch grains; these grains often completely fill the stone cells.</p>
-
-<p>The yellow stone cells of calumba root (Plate 65, Fig. 2)
-usually contain four prisms of calcium oxalate, which may be
-nearly uniform or very unequal in size.</p>
-
-<p><span class="pagenum" id="Page_179">[179]</span></p>
-
-<h5>BAST FIBRES</h5>
-
-<p>The <span class="bold">bast fibres</span> of the different rubus species (Plate 65,
-Fig. 7) contain starch. The medullary rays of quassia (Plate
-107, Fig. 2) contain starch; while the medullary rays of canella
-alba contain rosette crystals. In a cross-section of canella alba
-(Plate 81, Fig. 3) the crystals form parallel radiating lines which,
-upon closer examination, are seen to be medullary rays, in each
-cell of which a crystal usually occurs.</p>
-
-<p>The <span class="bold">epidermal and hypodermal cells of leaves</span> serve as
-water-storage tissue. These cells usually appear empty in a
-section.</p>
-
-<p>The barks of many plants&mdash;<em>i.e.</em>, quebracho, witch-hazel,
-cascara, frangula, the leaves of senna and coca, and the root
-of licorice&mdash;contain numerous crystals. These crystals occur in
-special storage cells&mdash;<span class="bold">crystal cells</span> (Plate 65, Fig. 6)&mdash;which
-usually form a completely enveloping layer around the bast
-fibres. These cells are usually the smallest cells of the plant
-in which they occur, and with but few exceptions each cell
-contains but a single crystal.</p>
-
-<p>The epidermal cells of senna leaves and the epidermal cells
-of mustard are filled with mucilage; the walls even consist of
-mucilage. Such cells are always diagnostic in powders.</p>
-
-<h4 id="STORAGE_WALLS">STORAGE WALLS</h4>
-
-<p><span class="bold">Storage walls</span> (Plates 68 and 69) occur in colchicum seed,
-saw palmetto seed, areca nut, nux vomica, and Saint Ignatius’s
-bean. In each of these seeds the walls are strongly and characteristically
-thickened and pitted. In no two plants are they
-alike, and in each plant they are important diagnostic characters.</p>
-
-<p>Storage cell walls consist of reserve cellulose, a form of
-cellulose which is rendered soluble by ferments, and utilized
-as food during the growth of the seed. Reserve cellulose is
-hard, bony, and of a waxy lustre when dry. Upon boiling in
-water the walls swell and become soft.</p>
-
-<p>The structure of the reserve cellulose varies greatly in the
-different seeds in which it occurs in the thickness of the walls
-and in the number and character of the pores.</p>
-
-<p><span class="pagenum" id="Page_180">[180]</span></p>
-
-<div class="figcenter illowp52" id="plate68" style="max-width: 133.375em;">
-  <img class="w100 p1" src="images/plate68.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 68</span><br />
-<span class="smcap">Reserve Cellulose</span>
-
-<div class="blockquotc">
-<p>1. Saw palmetto (<i lang="la" xml:lang="la">Serenoa serrulata</i>, [Michaux] Hook., f.).<br />
-<span class="pad1">2.</span> Areca nut (<i lang="la" xml:lang="la">Areca catechu</i>, L.).<br />
-<span class="pad1">3.</span> Colchicum seed (<i lang="la" xml:lang="la">Colchicum autumnale</i>, L.).<br />
-<span class="pad1">3-<em>A</em>.</span> Porous side wall.<br />
-<span class="pad1">3-<em>B</em>.</span> Cell cavity above the side wall.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_181">[181]</span></p>
-
-<div class="figcenter illowp53" id="plate69" style="max-width: 131.9375em;">
-  <img class="w100" src="images/plate69.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 69</span><br />
-<span class="smcap">Reserve Cellulose</span>
-
-<div class="blockquotc">
-<p>1. Endosperm of nux vomica (<i lang="la" xml:lang="la">Strychnos nux vomica</i>, L.).<br />
-<span class="pad1">2.</span> Endosperm of St. Ignatia bean (<i lang="la" xml:lang="la">Strychnos ignatii</i>, Berg.).</p>
-    </div>
-  </div>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_182">[182]</span></p>
-
-<h3 class="nobreak" id="PII_CHAPTER_IX">CHAPTER IX<br />
-<span class="fs80">CELL CONTENTS</span></h3>
-</div>
-
-<p>The cell contents of the plant are divided into two groups:
-first, organic cell contents; and secondly, inorganic cell contents.</p>
-
-<p>The <span class="bold">organic</span> cell contents include plastids, starch grains,
-mucilage, inulin, sugar, hesperidin, alkaloids, glucocides, tannin,
-resin, and oils.</p>
-
-<h4 id="CHLOROPHYLL">CHLOROPHYLL</h4>
-
-<p>The <span class="bold">chloroplasts</span> of the higher plants are green, and they
-vary somewhat in size, but they have a similar structure and
-form.</p>
-
-<p>Chloroplasts are mostly oval in longitudinal view and rounded
-in cross-section view. Each chlorophyll grain has an extremely
-thin outer wall, which encloses the protoplasmic substance, the
-green granules, a green pigment (chlorophyll), and a yellow
-pigment (xanthophyll). Frequently the wall includes starch,
-oil drops, and protein crystals.</p>
-
-<p>Chloroplasts are arranged either in a regular peripheral
-manner along the walls, or they are diffused throughout the
-protoplast.</p>
-
-<p>The palisade cells of most leaves are packed with chlorophyll
-grains. In the mesophyll cells the chlorophyll grains are not
-so numerous, and they are arranged peripherally around the
-innermost part of the wall.</p>
-
-<p>Chloroplasts multiply by fission&mdash;that is, each chloroplast
-divides into two equal halves, each of which develops into a
-normal chloroplast.</p>
-
-<p>Chlorophyll occurs in the palisade, spongy parenchyma, and
-guard cells of the leaf; in the collenchyma and parenchyma of
-the cortex of the stems of herbs and of young woody stems, and,
-under certain conditions, in rhizomes and roots exposed to
-light. Almost without exception young seeds and fruits have
-chlorophyll.</p>
-
-<p><span class="pagenum" id="Page_183">[183]</span></p>
-
-<p>In powdered leaves, stems, etc., the chlorophyll grains occur
-in the cells as greenish, more or less structureless masses. Yet
-cells with chlorophyll are readily distinguished from cells with
-other cell contents. In witch-hazel leaf the chlorophyll grains
-appear brownish in color. Powdered leaves and herbs are
-readily distinguished from bark, wood, root, and flower powders.</p>
-
-<p>Leaves and the stems of herbs are of a bright-green color.
-With the exception of the guard cells, the chloroplasts occur one
-or more layers below the epidermis; but, owing to the translucent
-nature of the outer walls of these cells, the outer cells of
-leaves and stems appear green.</p>
-
-<p>Wild cherry, sweet birch, and, in fact, most trees with smooth
-barks have <span class="bold">chloroplasts</span> in several of the outer layers of the
-cortical parenchyma. When the thin outer bark is removed
-from these plants, the underlying layers are seen to be of a
-bright-green color.</p>
-
-<h4 id="LEUCOPLASTIDS">LEUCOPLASTIDS</h4>
-
-<p><span class="bold">Leucoplastids</span>, or colorless plastids, occur in the underground
-portions of the plant; they may, when these organs in which
-they occur are exposed to light, change to chloroplastids.</p>
-
-<p>Leucoplasts are the builders of starch grains. They take
-the chemical substance starch and build or mould it into starch
-grains, storage starch, or reserve starch.</p>
-
-<p>Other characteristic chromoplasts found in plants are yellow
-and red. Yellow chromoplasts occur in carrot root and nasturtium
-flower petals. Red plastids occur in the ripe fruit of
-capsicum.</p>
-
-<h4 id="STARCH_GRAINS">STARCH GRAINS</h4>
-
-<p>The chemical substance starch (C₆H₁₀O₅) is formed in chloroplasts.
-The starch thus formed is removed from the chloroplasts
-to other parts of the plant because it is the function of
-the chloroplasts to manufacture and not to store starch.</p>
-
-<p>The starch formed by the chloroplasts is acted upon by a
-ferment which adds one molecule of water to C₆H₁₀O₅, thus
-forming sugar C₆H₁₂O₆. This sugar is readily soluble in the<span class="pagenum" id="Page_184">[184]</span>
-cell sap, and is conducted to all parts of the plant. The sugar
-not utilized in cell metabolism is stored away in the form of
-reserve starch or starch grains by colorless plastids or amyloplasts.</p>
-
-<p>The amyloplasts change the sugar into starch by extracting
-a molecule of water. This structureless material (starch) is
-then formed by the amyloplast into starch grains having a
-definite and characteristic form and structure.</p>
-
-<p>Starch grams vary greatly in different species of plants,
-owing probably to the variation of the chemical composition,
-density, etc., of the protoplast, and to the environmental conditions
-under which the plant is growing.</p>
-
-<h5 id="OCCURRENCE">OCCURRENCE</h5>
-
-<p>Starch grains are simple, compound, or aggregate. <span class="bold">Simple
-starch</span> grains may occur as isolated grains (Plates 70, 71, and
-72), or they may be associated as in cardamon seed, white pepper,
-cubeb, and grains of paradise, where the simple grains stick
-together in masses, having the outline of the cells in which they
-occur. These masses are known as aggregate starch.</p>
-
-<p><span class="bold">Aggregate starch</span> (Plate 76) varies greatly in size, form, and
-in the nature of the starch grains forming the aggregations.</p>
-
-<p><span class="bold">Compound starch grains</span> may be composed of two or more
-parts, and they are designated as 2, 3, 4, 5, etc., compound
-(Plate 75).</p>
-
-<p>The parts of a compound grain may be of equal size (Plate
-75, Fig. 4), or they may be of unequal size (Plate 75, Fig. 2).</p>
-
-<p>In most powders large numbers of the parts of the compound
-grains become separated. The part in contact with other
-grains shows plane surfaces, while the external part of the grain
-has a curved surface. There will be one plane and one curved
-surface if the grain is a half of a two-compound grain; two
-plane and one curved surface if the grain is a part of a three-compound
-grain, etc.</p>
-
-<p>The simple starch grains forming the aggregations become
-separated during the milling process and occur singly, so that
-in the drugs cited above the starch grains are solitary and
-aggregate.</p>
-
-<p>Many plants contain both simple and compound starch
-grains (Plate 74, Fig. 3).</p>
-
-<p><span class="pagenum" id="Page_185">[185]</span></p>
-
-<p>In some forms&mdash;<em>e.g.</em>, belladonna root (Plate 75, Fig. 2) the
-compound grains are more numerous; while in sanguinaria the
-simple grains are more numerous, etc.</p>
-
-<h5 id="OUTLINE">OUTLINE</h5>
-
-<p>The <span class="bold">outline</span> of starch grains is made up of (1) rounded, (2)
-angled, and (3) rounded and angled surfaces.</p>
-
-<p>Starch grains with rounded surfaces may be either spherical,
-as in Plate 74, Fig. 3, or oblong or elongated, as in Plate 71,
-Fig. 1.</p>
-
-<p>Other starches with rounded surfaces are shown on Plates
-72 and 73.</p>
-
-<p>Angled outlined grains are common to cardamon seed, white
-pepper, cubebs, grains of paradise (Plate 76, Fig. 4), and to corn
-(Plate 70, Fig. 3).</p>
-
-<p>The outlines of all compound grains are made up partly of
-plane and partly of curved surfaces.</p>
-
-<h5 id="SIZE">SIZE</h5>
-
-<p>The <span class="bold">size</span> (greatest diameter) of starch varies greatly even
-in the same species, but for each plant there is a normal variation.</p>
-
-<p>In spherical starch grains the size of the individual grains is
-invariable, but in elongated starch grains and in parts of compound
-grains the size will vary according to the part of the grain
-measured. In zedoary starch (Plate 71, Fig. 4), for instance,
-the size will vary according to whether the end, side, or surface
-of the starch grain is in focus.</p>
-
-<p>The parts of compound grains often vary greatly in size.
-Such a variation is shown in Plate 75, Fig. 2.</p>
-
-<h5 id="HILUM">HILUM</h5>
-
-<p>The <span class="bold">hilum</span> is the starting-point of the starch grain or the
-first part of the grain laid down by the amyloplast. The hilum
-will be central if formed in the middle of the amyloplast, and
-excentral if formed near the surface of the amyloplast. It
-has been shown that the developing starch grain with eccentric
-hilum usually extends the wall of the amyloplast if it does not
-actually break through the wall. Starch grains with excentral
-hilums are therefore longer than broad.</p>
-
-<p><span class="pagenum" id="Page_186">[186]</span></p>
-
-<div class="figcenter illowp52" id="plate70" style="max-width: 134.0625em;">
-  <img class="w100 p1" src="images/plate70.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 70</span><br />
-<span class="smcap">Starch</span>
-
-<div class="blockquotc">
-<p>1. Calabar bean (<i lang="la" xml:lang="la">Physostigma venenosum</i>, Balfour).<br />
-<span class="pad1">2.</span> Marshmallow root (<i lang="la" xml:lang="la">Althæa officinalis</i>, L.).<br />
-<span class="pad1">3.</span> Field corn (<i lang="la" xml:lang="la">Zea mays</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_187">[187]</span></p>
-
-<div class="figcenter illowp49" id="plate71" style="max-width: 130em;">
-  <img class="w100 p1" src="images/plate71.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 71</span><br />
-<span class="smcap">Starch</span>
-
-<div class="blockquotc">
-<p>1. Galanga root (<i lang="la" xml:lang="la">Alpinia officinarum</i>, Hance). 2. Kola nut
-(<i lang="la" xml:lang="la">Cola vera</i>, [K.] Schum.). 3. Geranium rhizome (<i lang="la" xml:lang="la">Geranium
-maculatum</i> L.). 4. Zedoary root (<i lang="la" xml:lang="la">Curcuma zedoaria</i>, Rosc.).
-4-<em>A</em>. Surface view of starch grain. 4-<em>B</em>. Side view of
-starch grain. 4-<em>C</em>. End view of starch grain.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_188">[188]</span></p>
-
-<p>In central hilum starch grains the grain is laid down around
-the hilum in the form of concentric layers. These layers are
-of variable density. The dense layers are formed when plenty
-of sugar is available, and the less dense layers are formed when
-little sugar is available. The unequal density of the different
-layers gives the striated appearance characteristic of so many
-starch grains.</p>
-
-<p>In eccentric hilum starch grains the starch will be deposited
-in layers which are outside of and successively farther from the
-hilum.</p>
-
-<p>The term <i lang="la" xml:lang="la">hilum</i> has come to have a broader meaning than
-formerly. Hilum includes at the present time not only the
-starting-point of the starch grain, but the fissures which form
-in the grain upon drying. In all cases these fissures originate
-in the starting-point, hilum, and in some cases extend for some
-distance from it. The hilum, when excentral, may occur in
-the broad end of the grain, galanga, and geranium (Plate 71,
-Figs, 1 and 3), or in the narrow end of the grain, zedoary (Plate
-71, Fig. 4).</p>
-
-<h5 id="NATURE_OF_THE_HILUM">NATURE OF THE HILUM</h5>
-
-<p>The hilum, whether central or excentral, may be rounded
-(Plate 75, Fig. 1); or simple cleft, which may be straight (Plate
-71, Fig. 1); or curved cleft (Plate 71, Fig. 2); or the hilum may
-be a multiple cleft (Plate 74, Fig. 3).</p>
-
-<p>In studying starches use cold water as the mounting medium,
-because in cold water the form and structure are best shown,
-and because there is no chemical action on the starch. On the
-other hand, the form and structure will vary considerably if
-the starch is mounted in hot water or in solutions of alkalies
-or acids. The hilum appears colorless when in sharp focus, and
-black when out of focus.</p>
-
-<p>Starch grains, when boiled with water, swell up and finally
-disintegrate to form starch paste.</p>
-
-<p>Starch paste turns blue upon the addition of a few drops of
-weak Lugol solution. Upon heating, this blue solution is decolorized,
-but the color reappears upon cooling. If a strong
-solution of Lugol is used in testing, the color will be bluish black.</p>
-
-<p><span class="pagenum" id="Page_189">[189]</span></p>
-
-<div class="figcenter illowp53" id="plate72" style="max-width: 132.6875em;">
-  <img class="w100 p1" src="images/plate72.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 72</span><br />
-<span class="smcap">Starch</span>
-
-<div class="blockquotc">
-<p>1. Orris root (<i lang="la" xml:lang="la">Iris florentinia</i> L.).<br />
-<span class="pad1">2.</span> Stillingia root (<i lang="la" xml:lang="la">Stillingia sylvatica</i>, L.).<br />
-<span class="pad1">3.</span> Calumba root (<i lang="la" xml:lang="la">Jateorhiza palmata</i>, [Lam.] Miers.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_190">[190]</span></p>
-
-<div class="figcenter illowp61" id="plate73" style="max-width: 129.9375em;">
-  <img class="w100 p1" src="images/plate73.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 73</span><br />
-<span class="smcap">Starch</span>
-
-<div class="blockquotc">
-<p>1. Male fern (<i lang="la" xml:lang="la">Dryopteris marginalis</i>, [L.] A. Gray).<br />
-<span class="pad1">2.</span> African ginger (<i lang="la" xml:lang="la">Zingiber officinalis</i>, Rosc.).<br />
-<span class="pad1">3.</span> Yellow dock (<i lang="la" xml:lang="la">Rumex crispus</i>, L.).<br />
-<span class="pad1">4.</span> Pleurisy root (<i lang="la" xml:lang="la">Asclepias tuberosa</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_191">[191]</span></p>
-
-<div class="figcenter illowp54" id="plate74" style="max-width: 130.9375em;">
-  <img class="w100 p1" src="images/plate74.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 74</span><br />
-<span class="smcap">Starch</span>
-
-<div class="blockquotc">
-<p>1. Kava-kava (<i lang="la" xml:lang="la">Piper methysticum</i>, Forst., f.).<br />
-<span class="pad1">2.</span> Pokeroot (<i lang="la" xml:lang="la">Phytolacca americana</i>, L.).<br />
-<span class="pad1">3.</span> Rhubarb (<i lang="la" xml:lang="la">Rheum officinale</i>, Baill.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_192">[192]</span></p>
-
-<div class="figcenter illowp54" id="plate75" style="max-width: 130.1875em;">
-  <img class="w100 p1" src="images/plate75.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 75</span><br />
-<span class="smcap">Starch Grains</span>
-
-<div class="blockquotc">
-<p>1. Bryonia (<i lang="la" xml:lang="la">Bryonia alba</i>, L.).<br />
-<span class="pad1">2.</span> Belladonna root (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.).<br />
-<span class="pad1">3.</span> Valerian root (<i lang="la" xml:lang="la">Valeriana officinalis</i>, L.).<br />
-<span class="pad1">4.</span> Colchicum root (<i lang="la" xml:lang="la">Colchicum autumnale</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_193">[193]</span></p>
-
-<div class="figcenter illowp53" id="plate76" style="max-width: 133em;">
-  <img class="w100 p1" src="images/plate76.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 76</span><br />
-<span class="smcap">Starch Masses</span>
-
-<div class="blockquotc">
-<p>1. Aggregate starch of cardamon seed (<i lang="la" xml:lang="la">Elettaria cardamomum</i>, Maton).<br />
-<span class="pad1">2.</span> Aggregate starch of white pepper (<i lang="la" xml:lang="la">Piper nigrum</i>, L.).<br />
-<span class="pad1">3.</span> Aggregate starch of cubebs (<i lang="la" xml:lang="la">Piper cubeba</i>, L., f.).<br />
-<span class="pad1">4.</span> Aggregate starch of <ins class="corr" id="tn193" title="Transcriber’s Note—“grains of paradise Amomum meleguetta” changed to “grains of paradise Amomum melegueta”.">grains of paradise (<i lang="la" xml:lang="la">Amomum melegueta</i></ins>, Rosc.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_194">[194]</span></p>
-
-<h4 id="INULIN">INULIN</h4>
-
-<p><span class="bold">Inulin</span> is the reserve carbohydrate material found in the
-plants of the composite family.</p>
-
-<p>The medicinal plants containing inulin are dandelion, chicory,
-elecampane, pyrethrum, and burdock. Plate 77, Figs, 1 and 2
-show masses of inulin in dandelion and pyrethrum.</p>
-
-<p>In these plants the inulin occurs in the form of irregular,
-structureless, grayish-white masses (Plate 77). In powdered
-drugs inulin occurs either in the parenchyma cell or as irregular
-isolated fragments of variable size and form. Inulin is structureless
-and the inulin from one plant cannot be distinguished
-microscopically from the inulin of another plant. For this
-reason inulin has little or no diagnostic value. The presence
-or absence of inulin should always be noted, however, in examining
-powdered drugs, because only a few drugs contain inulin.</p>
-
-<p>When cold water is added to a powder containing inulin it
-dissolves. Solution will take place more quickly, however, in
-hot water. Inulin occurs in the living plant in the form of cell
-sap. If fresh sections of the plant are placed in alcohol or
-glycerine, the inulin precipitates in the form of crystals.</p>
-
-<h4 id="MUCILAGE">MUCILAGE</h4>
-
-<p><span class="bold">Mucilage</span> is of common occurrence in medicinal plants.
-Characteristic mucilage cavities filled with mucilage occur in
-sassafras stem (Plate 66, Fig. 2), in elm bark (Plate 66, Fig. 1),
-in althea root, in the outer layer of mustard seed, and in the
-stem of cactus grandiflorus. In addition, mucilage is found
-associated with raphides in the crystal cells of sarsaparilla,
-squill, false unicorn, and polygonatum.</p>
-
-<p>When drugs containing mucilage are added to alcohol,
-glycerine, and water mixture, the mucilage swells slightly and
-becomes distinctly striated, but it will not dissolve for a long
-time. Refer to Plate 79, Fig. 6.</p>
-
-<p>Mucilage, when associated with raphides, swells and rapidly
-dissolves when added to alcohol, glycerine, and water mixture.
-The mucilage is, therefore, different from the mucilage found
-in mucilage cavities, because it is more readily soluble.</p>
-
-<p><span class="pagenum" id="Page_195">[195]</span></p>
-
-<div class="figcenter illowp52" id="plate77" style="max-width: 134.75em;">
-  <img class="w100 p1" src="images/plate77.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 77</span><br />
-<span class="smcap">Inulin</span> (<i lang="la" xml:lang="la">Inula helenium</i>, L.)
-
-<p>1. Inulin in the parenchyma cells of dandelion root.<br />
-<span class="pad1">2.</span> Inulin from Roman pyrethrum root (<i lang="la" xml:lang="la">Anacyclus pyrethrum</i>, [L.] D. C.).</p>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_196">[196]</span></p>
-
-<p>In coarse-powdered bark and other mucilage containing
-drugs the mucilage masses are mostly spherical or oval in outline
-(Plate 66, Figs. 2 and 3) the form being similar to the cavity
-in which the mass occurs.</p>
-
-<p>Acacia, tragacanth, and India gum consist of the dried
-mucilaginous excretions.</p>
-
-<h4 id="HESPERIDIN">HESPERIDIN</h4>
-
-<p><span class="bold">Hesperidin</span> occurs in the epidermal cells of short and long
-buchu. It is particularly characteristic in the epidermal cells
-of the dried leaves of short buchu. In these leaves the hesperidin
-occurs in masses which resemble rosette crystals (Plate 54, Fig. 1).</p>
-
-<p>Hesperidin is insoluble in glycerine, alcohol, and water, but
-it dissolves in alkali hydroxides, forming a yellowish solution.</p>
-
-<h4 id="VOLATILE_OIL">VOLATILE OILS</h4>
-
-<p><span class="bold">Volatile oils</span> occur in cinnamon stem bark, sassafras root
-bark, flowers of cloves, and in the fruits of allspice, anise, fennel,
-caraway, coriander, and cumin.</p>
-
-<p>In none of these cases is the volatile oil diagnostic, but its
-presence must always be determined.</p>
-
-<p>When a powdered drug containing a volatile oil is placed
-in alcohol, glycerine, and water mixture the volatile oil contained
-in the tissues will accumulate at the broken end of the
-cells in the form of rounded globules, while the volatile oil
-adhering to the surface of the fragments will dissolve in the
-mixture and float in the solution near the under side of the
-cover glass. Volatile oil is of little importance in histological
-work.</p>
-
-<h4 id="TANNIN">TANNIN</h4>
-
-<p><span class="bold">Tannin</span> masses are usually red or reddish brown. Tannin
-occurs in cork cells, medullary rays of white pine bark (Plate 48,
-Fig. B), stone cells, and in special tannin sacs.</p>
-
-<p>The stone cells of hemlock and tamarac bark and the medullary
-rays of white pine and hemlock bark contain tannin.</p>
-
-<p>Tannin associated with prisms occurs in tannin sacs in white
-pine and tamarac bark. These sacs are frequently several
-millimeters in length and contain a great number of crystals
-surrounded by tannin.</p>
-
-<p><span class="pagenum" id="Page_197">[197]</span></p>
-
-<p>Deposits of tannin are colored bluish black with a solution
-of ferric chloride.</p>
-
-<h4 id="ALEURONE_GRAINS">ALEURONE GRAINS</h4>
-
-<p><span class="bold">Aleurone grains</span> are small granules of variable structure,
-size, and form, and they are composed of reserve proteins.
-They occur in celery, fennel, coriander, and anise, fruits, in
-sesame, sunflower, curcas, castor oil, croton oil, bitter almond,
-and other oil seeds.</p>
-
-<p>In many of the seeds the aleurone grains completely fill the
-cells of the endosperm, embryo, and perisperm. In wheat, rye,
-barley, oats, and corn the aleurone grains occur only in the
-outer layer or layers of the endosperm, the remaining layers
-in these cases being filled with starch.</p>
-
-<p>In powdered drugs the aleurone grains occur in parenchyma
-cells or free in the field.</p>
-
-<h5 id="STRUCTURE_OF_ALEURONE_GRAINS">STRUCTURE OF ALEURONE GRAINS</h5>
-
-<p>Aleurone grains are very variable in structure. The simplest
-grains consist of an undifferentiated mass of proteid substance
-surrounded by a thin outer membrane. In other grains the
-proteid substance encloses one or more rounded denser proteid
-bodies known as globoids. In other grains a crystalloid&mdash;crystal-like
-proteid substance&mdash;is present in addition to the globoid.
-In some grains are crystals of calcium oxalate, which may occur
-as prisms or as rosettes. All the different parts, however, do
-not occur in any one grain. In castor-oil seed (Plate 77<em>a</em>, Fig. 8)
-are shown the membrane (<em>A</em>), the ground mass (<em>B</em>), the crystalloid
-(<em>C</em>), and the globoid (<em>D</em>).</p>
-
-<h5 id="FORM_OF_ALEURONE_GRAINS">FORM OF ALEURONE GRAINS</h5>
-
-<p>Much attention has been given to the study of the special
-parts of the aleurone grains, but one of the most important
-diagnostic characters has been overlooked, namely, that of
-comparative form. For the purposes of comparing the forms of
-different grains, they should be mounted in a medium in which
-the grain and its various parts are insoluble. Oil of cedar is
-such a medium. The variation in form and size of the aleurone
-grains when mounted in oil of cedar is shown in Plate 77<em>a</em>.</p>
-
-<p><span class="pagenum" id="Page_198">[198]</span></p>
-
-<h5 id="DESCRIPTION_OF_ALEURONE_GRAINS">DESCRIPTION OF ALEURONE GRAINS</h5>
-
-<p>The aleurone grains of curcas (Plate 77<em>a</em>, Fig. 1) vary in form
-from circular to lens-shaped, and each grain contains one or
-more globoids. The globoids are larger when they occur singly.
-In sunflower seed (Plate 77<em>a</em>, Fig. 2) the grains vary from reniform
-to oval, and one or more globoids are present; many occur
-in the center of the grain.</p>
-
-<p>The aleurone grains of flaxseed (Plate 77<em>a</em>, Fig. 3) resemble
-in form those of sunflower seed, but the grains are uniformly
-larger and some of the grains contain as many as five
-globoids.</p>
-
-<p>In bitter almond (Plate 77<em>a</em>, Fig. 4) the aleurone grains are
-mostly circular, but a few are nearly lens-shaped. A few of
-the large, rounded grains contain as many as nine globoids;
-in such cases one of the globoids is likely to be larger than the
-others. The aleurone grains of croton-oil seed (Plate 77<em>a</em>, Fig. 5)
-are circular in outline, variable in form, and each grain contains
-from one to seven globoids.</p>
-
-<p>In sesame seed (Plate 77<em>a</em>, Fig. 6) the typical grain is angled
-in outline and the large globoid occurs in the narrow or constricted
-end.</p>
-
-<p>The aleurone grains of castor-oil seed (Plate 77<em>a</em>, Fig. 7) resemble
-those of sesame seed, but they are much larger, and
-many of the grains contain three large globoids. When these
-grains are mounted in sodium-phosphate solution, the crystalloid
-becomes visible.</p>
-
-<h5 id="TESTS_FOR_ALEURONE_GRAINS">TESTS FOR ALEURONE GRAINS</h5>
-
-<p>Aleurone grains are colored yellow with nitric acid and red
-with Millon’s reagent.</p>
-
-<p>The proteid substance of the mass of the grain, of the globoid,
-and of the crystalloid, reacts differently with different reagents
-and dyes.</p>
-
-<p>The ground substance and the crystalloids are soluble in
-dilute alkali, while the globoids are insoluble in dilute alkali.</p>
-
-<p>The ground substance and crystalloids are soluble in sodium
-phosphate, while the globoids are insoluble in sodium phosphate.</p>
-
-<p>Calcium oxalate is insoluble in alkali and acetic acid, but
-it dissolves in hydrochloric acid.</p>
-
-<p><span class="pagenum" id="Page_199">[199]</span></p>
-
-<div class="figcenter illowp56" id="plate77a" style="max-width: 131.3125em;">
-  <img class="w100 p1" src="images/plate77a.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 77<em>a</em></span><br />
-<span class="smcap">Aleurone Grains</span>
-
-<div class="blockquotc">
-<p>1. Curcas (<i lang="la" xml:lang="la">Jatropha curcas</i>, L.).<br />
-<span class="pad1">2.</span> Sunflower seed (<i lang="la" xml:lang="la">Helianthus annuus</i>, L.).<br />
-<span class="pad1">3.</span> Flaxseed (<i lang="la" xml:lang="la">Linum usitatissimum</i>, L.).<br />
-<span class="pad1">4.</span> Bitter almond (<i lang="la" xml:lang="la">Prunus amygdalus</i>, <i lang="la" xml:lang="la">amara</i>, D.C.).<br />
-<span class="pad1">5.</span> Croton-oil seed (<i lang="la" xml:lang="la">Croton tiglium</i>, L.).<br />
-<span class="pad1">6.</span> Sesame seed (<i lang="la" xml:lang="la">Sesamum indicum</i>, L.).<br />
-<span class="pad1">7 and 8.</span> Castor-oil seed (<i lang="la" xml:lang="la">Ricinus communis</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_200">[200]</span></p>
-
-<h4 id="CRYSTALS">CRYSTALS</h4>
-
-<p>Calcium oxalate crystals form one of the most important
-inorganic cell contents found in plants, because of the permanency
-of the crystals, and because the forms common to
-a given species are invariable. By means of calcium oxalate
-crystals it is possible to distinguish between different species.
-In butternut root bark, for instance, only rosette crystals are
-found, while in black walnut root bark&mdash;a common substitute
-for butternut bark&mdash;both prisms and rosettes occur. This is
-only one of the many examples which could be cited.</p>
-
-<p>These crystals, for purposes of study, will be grouped into
-four principal classes, depending upon form and not upon crystal
-system. These classes are micro-crystals, raphides, rosettes,
-and solitary crystals.</p>
-
-<h5 id="MICRO-CRYSTALS">MICRO-CRYSTALS</h5>
-
-<p><span class="bold">Micro-crystals</span> are the smallest of all the crystals. Under the
-high power of the microscope they appear as a V, a Y, an X,
-and as a T. They are, therefore, three- or four-angled (Plate 78).
-The thicker portions of these crystals are the parts usually
-seen, but when a close observation of the crystals is made the
-thin portions of the crystal connecting the thicker parts may
-also be observed. Micro-crystals should be studied with the
-diaphragm of the microscope nearly closed and with the high-power
-objective in position. While observing the micro-crystals,
-raise and lower the objective by the fine adjustment in order to
-bring out the structure of the crystal more clearly. Micro-crystals
-occur in parenchyma cells of belladonna, scopola,
-stramonium, and bittersweet leaves; in belladonna, in horse-nettle
-root, in scopola rhizome, in bittersweet stems, and in
-yellow and red cinchona bark, etc.</p>
-
-<p>The crystals in each of the above parts of the plant are similar
-in form, the only observed variation being that of size. Their
-presence or absence should always be noted when studying
-powders.</p>
-
-<h5 id="RAPHIDES">RAPHIDES</h5>
-
-<p><span class="bold">Raphides</span>, which are usually seen in longitudinal view, resemble
-double-pointed needles. They are circular in cross-section,
-and the largest diameter is at the centre, from which
-they taper gradually toward either end to a sharp point.</p>
-
-<p><span class="pagenum" id="Page_201">[201]</span></p>
-
-<div class="figcenter illowp56" id="plate78" style="max-width: 124.0625em;">
-  <img class="w100 p1" src="images/plate78.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 78</span><br />
-<span class="smcap">Micro-Crystals</span>
-
-<div class="blockquotc">
-<p>1. Horse-nettle root (<i lang="la" xml:lang="la">Solanum carolinense</i>, L.).<br />
-<span class="pad1">2.</span> Scopola rhizome (<i lang="la" xml:lang="la">Scopolia carniolica</i>, Jacq.).<br />
-<span class="pad1">3.</span> Belladonna root (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.).<br />
-<span class="pad1">4.</span> Bittersweet stem (<i lang="la" xml:lang="la">Solanum dulcamara</i>, L.).<br />
-<span class="pad1">5.</span> Scopola leaf (<i lang="la" xml:lang="la">Scopola carniolica</i>, Jacq.).<br />
-<span class="pad1">6.</span> Tobacco leaf (<i lang="la" xml:lang="la">Nicotiana tabacum</i>, L.).<br />
-<span class="pad1">7.</span> Belladonna leaf (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_202">[202]</span></p>
-
-<p>Raphides occur in bundles, as in false unicorn root (Plate 79,
-Figs. 6, A, B, and C), rarely as solitary crystals.</p>
-
-<p>In ipecac root the crystals are usually solitary. In sarsaparilla
-root, squill, etc., the raphides occur both in clusters,
-part of bundle, or in bundles, and as solitary crystals.</p>
-
-<p>In most drugs the crystals are entire; but in squills, where
-the raphides are very large, they are broken. In phytolacca
-(Plate 79, Fig. 1) and in hydrangea the raphides are usually
-broken, owing to the fact that these drugs contain large quantities
-of fibres which break them up into fragments when the
-drug is milled.</p>
-
-<p>There is the greatest possible variation in the size of raphides
-in the same and in different drugs, but the larger forms are
-constant in the same species.</p>
-
-<p>Raphides are deposited in parenchyma cells and in special
-raphides sacs. These crystals are always surrounded with
-mucilage.</p>
-
-<h5 id="ROSETTE_CRYSTALS">ROSETTE CRYSTALS</h5>
-
-<p><span class="bold">Rosette crystals</span> are compound crystals composed of an
-aggregation of small crystals arranged in a radiating manner
-around a central core. This core appears nearly black, and
-the whole mass is nearly spherical. The free ends of the crystals
-are sharp-pointed or blunt.</p>
-
-<p>Characteristic rosette crystals occur in frangula bark, spikenard
-root, wahoo stem, root bark, rhubarb, etc. (Plate 80,
-Figs. 1, 2, 3, 4, 5, and 6).</p>
-
-<p>These crystals are very variable in size. This variation is
-illustrated by the crystals of Plate 80.</p>
-
-<p>Usually there is a variation in size of the crystals occurring
-in a given plant, but for each plant there is a more or less uniform
-variation. For instance, the largest rosette crystal occurring
-in wahoo root bark (Plate 80, Fig. 5) is smaller than the
-largest crystal occurring in rhubarb (Plate 80, Fig. 6), etc.</p>
-
-<p><span class="pagenum" id="Page_203">[203]</span></p>
-
-<div class="figcenter illowp55" id="plate79" style="max-width: 134.75em;">
-  <img class="w100 p1" src="images/plate79.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 79</span><br />
-<span class="smcap">Raphides</span>
-
-<div class="blockquotc">
-<p>1. Phytolacca root (<i lang="la" xml:lang="la">Phytolacca americana</i>, L.). 2. Squills (<i lang="la" xml:lang="la">Urginea maritima</i>
-[L.] Baker). 3. Hydrangea root (<i lang="la" xml:lang="la">Hydrangea arborescens</i>, L.). 4. Convallaria
-(<i lang="la" xml:lang="la">Convallaria majalis</i>, L.). 5. Carthagean ipecac (<i lang="la" xml:lang="la">Cephælis acuminata</i>
-Karst.) 6. Bundle of raphides from false unicorn root.<br />
-<span class="pad1"><em>A.</em></span> Bundle surrounded with mucilage. <em>B.</em> Mucilage expanded and partially
-dissolved. <em>C.</em> Bundle free of mucilage.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_204">[204]</span></p>
-
-<div class="figcenter illowp52" id="plate80" style="max-width: 123.375em;">
-  <img class="w100 p1" src="images/plate80.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 80</span><br />
-<span class="smcap">Rosette Crystals</span>
-
-<p>1. Frangula bark (<i lang="la" xml:lang="la">Rhamnus frangula</i>, L.).<br />
-<span class="pad1">2.</span> White oak bark (<i lang="la" xml:lang="la">Quercus alba</i>, L.).<br />
-<span class="pad1">3.</span> Spikenard root (<i lang="la" xml:lang="la">Aralia racemosa</i>, L.).<br />
-<span class="pad1">4.</span> Wahoo stem bark (<i lang="la" xml:lang="la">Euonymus atropurpureus</i>, Jacq.).<br />
-<span class="pad1">5.</span> Wahoo root bark (<i lang="la" xml:lang="la">Euonymus atropurpureus</i>, Jacq.).<br />
-<span class="pad1">6.</span> Rhubarb (<i lang="la" xml:lang="la">Rheum officinale</i>, Baill.).</p>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_205">[205]</span></p>
-
-<p>The prisms forming the rosette crystals, like all prisms,
-decompose white light, with the result that rosette crystals
-frequently appear variously colored. Rhubarb crystals, for
-instance, are blue or violet. Most of the smaller rosette crystals,
-however, appear grayish white with a darker-colored centre.</p>
-
-<p>Rosette crystals occur in parenchyma cells (Plate 81, Fig. 4)
-and in medullary rays (Plate 81, Fig. 3).</p>
-
-<h5 id="SOLITARY_CRYSTALS">SOLITARY CRYSTALS</h5>
-
-<p><span class="bold">Solitary crystals</span> are the most variable of all the forms of
-calcium oxalate. They usually occur in crystal cells associated
-with bast fibres and stone cells, less frequently in stone cells
-(Plate 33, Fig. 2). There are many different and characteristic
-forms of prisms. The more common are:</p>
-
-<p>1. Rectangular:<br />
-<span class="pad2">A. Parallelepipeds.</span><br />
-<span class="pad2">B. Cubes.</span><br />
-<span class="pad1">2.</span> Polyhedrons:<br />
-<span class="pad2">A. Irregular polyhedrons.</span><br />
-<span class="pad3h">I. Flat bases.</span><br />
-<span class="pad4h">(<em>a</em>) Non-notched.</span><br />
-<span class="pad4h">(<em>b</em>) Notched.</span><br />
-<span class="pad3">II. Tapering bases.</span><br />
-<span class="pad2">B. Octohedrons.</span></p>
-
-<p>The crystals occurring in Batavia cinnamon and henbane
-leaves are parallelopipeds (Plate 82, Figs. 1 and 2).</p>
-
-<p>The crystals occurring in cactus grandiflorus, hemlock bark,
-krameria root, and soap bark are irregular polyhedrons (Plate
-83). They are longer than broad, and the ends are tapering.
-The crystal of cactus grandiflorus has the narrowest diameter
-of these four, while the crystals of soap bark have the widest
-diameter. In coca leaf, xanthoxylum bark, elm bark, Spanish
-licorice, and in white oak (Plate 84), and in cocillina bark (Plate
-82, Fig. 4) the crystals are all irregular polyhedrons with flat
-bases. They are mostly longer than broad and they are all
-widest in the centre; in each a few crystals are notched, but
-most of the crystals are not notched.</p>
-
-<p>The crystals in quassia wood, uva-ursi leaf, and most of those
-of quebracho and wild cherry bark (Plate 86, Figs. 1, 2, 3, and 4)
-are irregular polyhedrons with flat ends. They are longer than
-broad, widest at the centre, and non-notched.</p>
-
-<p><span class="pagenum" id="Page_206">[206]</span></p>
-
-<div class="figcenter illowp51" id="plate81" style="max-width: 128.5625em;">
-  <img class="w100 p1" src="images/plate81.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 81</span><br />
-<span class="smcap">Inclosed Rosette Crystals</span>
-
-<p>1. Hops (<i lang="la" xml:lang="la">Humulus lupulus</i>, L.).<br />
-<span class="pad1">2.</span> Bracts of cannabis indica (<i lang="la" xml:lang="la">Cannabis sativa</i>, variety <i lang="la" xml:lang="la">Indica</i>, Lamarck).<br />
-<span class="pad1">3.</span> Medullary rays of canella alba.<br />
-<span class="pad1">4.</span> Parenchyma cells of mandrake (<i lang="la" xml:lang="la">Podophyllum peltatum</i>, L.).</p>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_207">[207]</span></p>
-
-<div class="figcenter illowp57" id="plate82" style="max-width: 124.5em;">
-  <img class="w100 p1" src="images/plate82.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 82</span><br />
-<span class="smcap">Solitary Crystal</span>
-
-<div class="blockquotc">
-<p>1. Batavia cinnamon (<i lang="la" xml:lang="la">Cinnamomum burmanni</i>, Nees).<br />
-<span class="pad1">2.</span> Henbane leaves (<i lang="la" xml:lang="la">Hyoscyamus niger</i>, L.).<br />
-<span class="pad1">3.</span> Morea nutgalls.<br />
-<span class="pad1">4.</span> Cocillana bark (<i lang="la" xml:lang="la">Guarea rusbyi</i> [Britton], Rusby).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_208">[208]</span></p>
-
-<div class="figcenter illowp53" id="plate83" style="max-width: 130.3125em;">
-  <img class="w100 p1" src="images/plate83.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 83</span><br />
-<span class="smcap">Solitary Crystals</span>
-
-<div class="blockquotc">
-<p>1. Cactus grandiflorus (<i lang="la" xml:lang="la">Cereus grandiflorus</i> [L.], Britton and Rose).<br />
-<span class="pad1">2.</span> Hemlock bark (<i lang="la" xml:lang="la">Tsuga canadensis</i> [L.], Carr.).<br />
-<span class="pad1">3.</span> Krameria root (<i lang="la" xml:lang="la">Krameria triandra</i>, Ruiz and Pav.).<br />
-<span class="pad1">4.</span> Soapbark (<i lang="la" xml:lang="la">Quillaja saponaria</i>, Molina).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_209">[209]</span></p>
-
-<div class="figcenter illowp52" id="plate84" style="max-width: 126.8125em;">
-  <img class="w100 p1" src="images/plate84.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 84</span><br />
-<span class="smcap">Solitary Crystals</span>
-
-<div class="blockquotc">
-<p>1. Coca leaf (<i lang="la" xml:lang="la">Erythroxylon coca</i>, Lamarck).<br />
-<span class="pad1">2.</span> Xanthoxylum bark (<i lang="la" xml:lang="la">Zanthoxylum americanum</i>, Miller).<br />
-<span class="pad1">3.</span> Elm bark (<i lang="la" xml:lang="la">Ulmus fulva</i>, Michaux).<br />
-<span class="pad1">4.</span> Spanish licorice root (<i lang="la" xml:lang="la">Glycyrrhiza glabra</i>, L.).<br />
-<span class="pad1">5.</span> White oak bark (<i lang="la" xml:lang="la">Quercus alba</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_210">[210]</span></p>
-
-<p>Cubes occur in senna, cascara sagrada, frangula, white pine,
-tamarac (Plate 85), quassia, uva-ursi, quebracho, and in wild
-cherry (Plate 86).</p>
-
-<p>The crystals of morea nutgalls (Plate 82, Fig. 3) are octahedrons,
-and they resemble the crystals of calcium oxalate found
-in urinary sediments.</p>
-
-<p>While studying the prisms, focus first on the upper surface
-and then down to the under surface in order to observe the
-forms accurately.</p>
-
-<p>There are several plants in which more than one form of
-crystal occur. Rosette crystals and prisms are associated, for
-instance, in cascara sagrada, frangula, condurango, dogwood,
-and pleurisy root (Plate 87, Figs. 1, 2, 3, 4, and 5).</p>
-
-<p>An important factor to be kept in mind in studying crystals
-is the number&mdash;whether abundant, as in rhubarb, or sparingly
-present, as in mandrake, etc. Variation in the number of
-crystals is not uncommon, even in different parts of the same
-plants. In wahoo stem bark, for instance, there are several
-times as many rosette crystals as there are in the root bark.</p>
-
-<p>Crystals of calcium oxalate are freely soluble in dilute
-hydrochloric acid without effervescence; but they are insoluble
-in acetic acid and in sodium and potassium hydroxide solutions.
-With sulphuric acid they form crystals of calcium sulphate.</p>
-
-<h4 id="CYSTOLITHS">CYSTOLITHS</h4>
-
-<p><span class="bold">Cystoliths</span> consist of calcium carbonate deposited over and
-around a framework of cellulose.</p>
-
-<h5 id="FORMS_OF_CYSTOLITHS">FORMS OF CYSTOLITHS</h5>
-
-<p>The <span class="bold">forms of cystoliths</span> differ greatly in the different plants
-in which they occur.</p>
-
-<p>In the rubber-plant leaf, the cystolith resembles a bunch of
-grapes and is stalked; in ruellia root (Plate 87, Fig. 1) the cystoliths
-vary from nearly circular to narrowly cylindrical, and no
-stalk is present; also the cystolith nearly fills the cell in which
-it occurs. In the hair of cannabis indica (Plate 88, Fig. 3), the
-cystolith varies in form according to the size and shape of the
-hair, but in all the hairs the cystolith appears to be attached to
-the upper curved part of the inner wall of the hair.</p>
-
-<p><span class="pagenum" id="Page_211">[211]</span></p>
-
-<div class="figcenter illowp52" id="plate85" style="max-width: 127.5625em;">
-  <img class="w100 p1" src="images/plate85.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 85</span><br />
-<span class="smcap">Solitary Crystals</span>
-
-<div class="blockquotc">
-<p>1. India senna (<i lang="la" xml:lang="la">Cassia angustifolia</i>, Vahl.).<br />
-<span class="pad1">2.</span> Cascara sagrada bark (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D. C.).<br />
-<span class="pad1">3.</span> Frangula bark (<i lang="la" xml:lang="la">Rhamnus frangula</i>, L.).<br />
-<span class="pad1">4.</span> White pine bark (<i lang="la" xml:lang="la">Pinus strobus</i>, L.).<br />
-<span class="pad1">5.</span> Tamarac bark (<i lang="la" xml:lang="la">Larix laricina</i> [Du Roi], Koch).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_212">[212]</span></p>
-
-<div class="figcenter illowp56" id="plate86" style="max-width: 131.6875em;">
-  <img class="w100 p1" src="images/plate86.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 86</span><br />
-<span class="smcap">Solitary Crystals</span>
-
-<div class="blockquotc">
-<p>1. Quassia (<i lang="la" xml:lang="la">Picræna excelsa</i> [Swartz.], Lindl.).<br />
-<span class="pad1">2.</span> Uva-ursi leaf (<i lang="la" xml:lang="la">Arctostaphylos uva-ursi</i> [L.], Spring.).<br />
-<span class="pad1">3.</span> Quebracho bark (<i lang="la" xml:lang="la">Aspidosperma quebracho-blanco</i>, Schlechtendal).<br />
-<span class="pad1">4.</span> Wild-cherry bark (<i lang="la" xml:lang="la">Prunus serotina</i>, Ehrh.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_213">[213]</span></p>
-
-<div class="figcenter illowp54" id="plate87" style="max-width: 131.3125em;">
-  <img class="w100 p1" src="images/plate87.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 87</span><br />
-<span class="smcap">Rosette Crystals and Solitary Crystals Occurring in</span>
-
-<div class="blockquotc">
-<p>1. Cascara sagrada bark (<i lang="la" xml:lang="la">Rhamnus purshiana</i>, D.C.).<br />
-<span class="pad1">2.</span> Frangula bark (<i lang="la" xml:lang="la">Rhamnus frangula</i>, L.).<br />
-<span class="pad1">3.</span> Cundurango bark (<i lang="la" xml:lang="la">Marsdenia cundurango</i>, [Triana] Nichols).<br />
-<span class="pad1">4.</span> Dogwood root bark (<i lang="la" xml:lang="la">Cornus florida</i>, L.).<br />
-<span class="pad1">5.</span> Pleurisy root (<i lang="la" xml:lang="la">Asclepias tuberosa</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_214">[214]</span></p>
-
-<div class="figcenter illowp51" id="plate88" style="max-width: 135.375em;">
-  <img class="w100 p1" src="images/plate88.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 88</span><br />
-<span class="smcap">Cystoliths</span>
-
-<div class="blockquotc">
-<p>1. Ruellia root (<i lang="la" xml:lang="la">Ruellia ciliosa</i>, Pursh.).<br />
-<span class="pad1">2.</span> Pellionia leaf.<br />
-<span class="pad1">3.</span> Cannabis indica (<i lang="la" xml:lang="la">Cannabis sativa</i>, variety <i lang="la" xml:lang="la">Indica</i>, Lam.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_215">[215]</span></p>
-
-<p>Cystoliths occur, then, in special cavities, in parenchyma
-cells (rubber-plant leaf, fig, pellionea, and mulberry), and in
-non-glandular hairs (cannabis indica).</p>
-
-<p>In powdered ruellia root the cystoliths occur in or are separated
-from the parenchyma cells.</p>
-
-<h5 id="TESTS_FOR_CYSTOLITHS">TESTS FOR CYSTOLITHS</h5>
-
-<p>When dilute hydrochloric acid or acetic acid is added to
-cystoliths a brisk effervescence takes place with the evolution
-of carbon dioxide gas.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<p><span class="pagenum" id="Page_216">[216]</span><br />
-<span class="pagenum" id="Page_217">[217]</span><br />
-<span class="pagenum" id="Page_218">[218]</span></p>
-
-<div class="chapter">
-<h2 class="nobreak p8" id="Part_III">Part III<br />
-<span class="fs80">HISTOLOGY OF ROOTS, RHIZOMES, STEMS,<br />
-BARKS, WOODS, FLOWERS, FRUITS,<br />
-AND SEEDS</span></h2>
-</div>
-
-<div class="blockquot">
-<p>In Part II the different types of cells and cell contents found
-in plants have been studied. In Part III it will be shown how
-these different cells are associated and the nature of the cell
-contents in the different parts of the plant. These parts are
-the root, the rhizome, the stem of herbs, bark and wood of
-woody stems, the leaf, the flower, the fruit, and the seed.</p>
-</div>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_219">[219]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_I">CHAPTER I<br />
-<span class="fs80">ROOTS AND RHIZOMES</span></h3>
-</div>
-
-<p>Some fifty-five roots, rhizomes, and rhizomes and roots are
-official in the pharmacopœia and national formulary. About
-5 of these are obtained from monocotyledonous plants, and
-50 from dicotyledonous plants.</p>
-
-<p>In studying the structure of roots and rhizomes, then, it
-must first be determined whether the root in question is monocotyledonous
-or dicotyledonous. This fact is ascertained by
-determining the type of the fibro-vascular bundle. The bundle
-is of the open collateral type in all rhizomes and roots obtained
-from monocotyledonous plants, but it is closed, radial, or concentric
-in the monocotyledonous type.</p>
-
-<p>In both of these groups the cellular plan of structure is
-similar, the chief variation being the absence of one or more
-types of cells, the variation in the amount, in arrangement, in
-the anatomical structure, in the color, and in the cell contents
-of the individual cells. These facts will be impressed on the
-mind while studying the rhizomes and the roots.</p>
-
-<h5 id="CROSS-SECTION_PINK_ROOT">CROSS-SECTION PINK ROOT</h5>
-
-<p>The cross-section of pink root (Plate 89) has the following
-structure:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells are small, nearly as long
-as broad, and the outer wall is thicker and darker in color than
-the side and inner walls. The cells usually contain air.</p>
-
-<p><span class="bold">Cortex.</span> The cortical parenchyma cells are very large and
-somewhat rounded in outline, and the walls are white. There
-are about twelve rows of these cells, and each cell contains
-numerous small, rounded starch grains.</p>
-
-<p><span class="bold">Endodermis.</span> The endodermal cells are tangentially elongated,
-and the walls are very thin and white. There are two
-or three layers of endodermal cells; the cells’ outer layers are
-larger than the cells of the inner layers.</p>
-
-<p><span class="pagenum" id="Page_220">[220]</span></p>
-
-<div class="figcenter illowp46" id="plate89" style="max-width: 129.25em;">
-  <img class="w100 p1" src="images/plate89.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 89</span><br />
-<span class="smcap">Cross-section of Root of Spigelia marylandica, L.</span>
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Cortical parenchyma. 2´. Intercellular space. 3. Endodermis.
-4. Pericycle. 5. Cambium. 6. Xylem. 7. Pith.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_221">[221]</span></p>
-
-<p><span class="bold">Pericycle.</span> The cells forming the pericycle are sieve cells
-and phloem parenchyma. The <span class="bold">sieve cells</span> are small, angled cells
-with extremely thin, white walls.</p>
-
-<p>The <span class="bold">phloem parenchyma</span> resemble the sieve cells, except
-that they are larger.</p>
-
-<p><span class="bold">Cambium.</span> The cambium cells are rectangular in shape;
-the walls are thin and white.</p>
-
-<p><span class="bold">Xylem.</span> The xylem is composed of tracheids, wood parenchyma,
-and wood fibres.</p>
-
-<p><span class="bold">Tracheids.</span> The tracheids are the largest diameter cells of
-the centre of the root. The walls are thick and the cells are
-slightly angled in outline.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells surrounding
-the tracheids are five to seven, angled, and the walls are not
-so thick as the walls of the tracheids.</p>
-
-<p><span class="bold">Medullary Rays.</span> The medullary ray cells resemble the
-structure of the wood parenchyma cells, but they are radially
-elongated.</p>
-
-<p><span class="bold">Pith Parenchyma.</span> The cells forming the pith parenchyma
-are larger than the cells of wood parenchyma, but their structure
-is similar.</p>
-
-<h5 id="CROSS-SECTION_RUELLIA_ROOT">CROSS-SECTION RUELLIA ROOT</h5>
-
-<p>The cross-section of ruellia root (Plate 90) shows the following
-structure. It should be carefully noted how the structure
-differs from that of pink root:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells are angled and variable in
-size; many of the epidermal cells are modified as root hairs.</p>
-
-<p><span class="bold">Hypodermis.</span> The cells of the hypodermis are one layer
-in thickness and their structure is similar to the epidermal
-cells.</p>
-
-<p><span class="bold">Cortex.</span> The cortex contains parenchyma and stone cells.
-The outer layers of the cortical parenchyma cells are round in
-outline, and they contain dark-brown cell contents, while the
-cortical parenchyma cells bordering on the endodermis are small
-and they are free of dark-brown contents.</p>
-
-<p>Many of the inner parenchyma cells contain amorphous
-deposits of calcium carbonate.</p>
-
-<p><span class="pagenum" id="Page_222">[222]</span></p>
-
-<div class="figcenter illowp51" id="plate90" style="max-width: 129.25em;">
-  <img class="w100 p1" src="images/plate90.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 90</span><br />
-<span class="smcap">Ruellia Root</span> (<i lang="la" xml:lang="la">Ruellia ciliosa</i>, Pursh.).
-
-<div class="blockquotc">
-<p>1. Epidermis with root hair. 2. Parenchyma cells with dark contents.
-3. Sclerid. 4. Parenchyma without dark cell contents. 5. Endodermis.
-6. Bast fibers and phloem. 7. Cambium. 8. Xylem. 10. Pith.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_223">[223]</span></p>
-
-<p>The <span class="bold">stone cells</span> are porous and striated, and the walls are
-thick and white.</p>
-
-<p><span class="bold">Endodermis.</span> The endodermal cells are tangentially elongated,
-and the walls are thin and white.</p>
-
-<p><span class="bold">Pericycle.</span> The cells forming the pericycle are the sieve
-cells, bast fibres, and phloem parenchyma.</p>
-
-<p>The <span class="bold">sieve cells</span> are small, angled cells with thin, white walls.</p>
-
-<p>The <span class="bold">phloem parenchyma</span> cells resemble the sieve cells, but
-they are larger.</p>
-
-<p>The <span class="bold">bast fibres</span> occur singly or in groups of two or three.
-They are rounded in outline, and the walls are white, non-porous,
-and non-striated.</p>
-
-<p><span class="bold">Xylem.</span> The xylem is composed of vessels, wood parenchyma,
-and wood fibres.</p>
-
-<p><span class="bold">Vessels.</span> The vessels are rounded in outline and few in
-number.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells are variable
-in size and shape, but all the cells are angled in outline.</p>
-
-<p><span class="bold">Medullary Rays.</span> The medullary ray cells are not clearly
-distinguishable.</p>
-
-<p><span class="bold">Pith Parenchyma.</span> The pith parenchyma cells of the centre
-of the root resemble the cortical parenchyma cells.</p>
-
-<p>That the structure of rhizomes is similar to the structure of
-roots is shown by the drawings of spigelia rhizome (Plate 91),
-and by ruellia rhizome (Plate 92).</p>
-
-<h5 id="CROSS-SECTION_SPIGELIA_RHIZOME">CROSS-SECTION SPIGELIA RHIZOME</h5>
-
-<p>The cross-section of spigelia rhizome (Plate 91) is as follows:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells are nearly angled and free
-of cell contents.</p>
-
-<p><span class="bold">Cortex.</span> The cortical parenchyma cells are usually slightly
-tangentially elongated. The cells of the outer layers are larger
-than the cells of the inner layers.</p>
-
-<p><span class="bold">Phloem.</span> The phloem contains sieve cells and phloem
-parenchyma. The sieve cells are small, angled cells with thin,
-white walls.</p>
-
-<p>The phloem parenchyma cells resemble the sieve cells, but
-they are larger.</p>
-
-<p><span class="pagenum" id="Page_224">[224]</span></p>
-
-<div class="figcenter illowp45" id="plate91" style="max-width: 121.6875em;">
-  <img class="w100 p1" src="images/plate91.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 91</span><br />
-<span class="smcap">Cross-Section of Rhizome of Spigelia marylandica, L.</span>
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Cortical parenchyma. 3. Phloem. 4. Cambium.
-5. Xylem. 6. Internal phloem. 7. Pith with starch.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_225">[225]</span></p>
-
-<div class="figcenter illowp47" id="plate92" style="max-width: 123.75em;">
-  <img class="w100 p1" src="images/plate92.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 92</span><br />
-<span class="smcap">Cross-Section of Rhizome of Ruellia ciliosa</span>, Pursh.
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Cystolith. 3. Stone cell. 4. Cortical parenchyma.
-5. Bast fibres. 6. Pericycle. 7. Xylem. 8. Pith.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_226">[226]</span></p>
-
-<p><span class="bold">Cambium.</span> The cambium cells are rectangular, and they are
-usually not clearly seen because the walls are partially
-collapsed.</p>
-
-<p><span class="bold">Xylem.</span> The xylem is composed of vessels, wood parenchyma,
-medullary rays, and pith parenchyma.</p>
-
-<p><span class="bold">Vessels.</span> The vessels are slightly angled in outline and few
-in number.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells are small
-and angled.</p>
-
-<p><span class="bold">Medullary Rays.</span> The medullary ray cells are tangentially
-elongated, but in structure resemble the wood parenchyma cells.</p>
-
-<p><span class="bold">Pith Parenchyma.</span> The pith parenchyma cells are rounded
-in outline and contain small, simple, rounded starch grains.</p>
-
-<h5 id="CROSS-SECTION_RUELLIA_RHIZOME">CROSS-SECTION RUELLIA RHIZOME</h5>
-
-<p>The cross-section of ruellia rhizome (Plate 92) differs from
-the structure of spigelia rhizome. It is as follows:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells vary in shape from nearly
-square to oblong, and they are filled with dark-brown cell
-contents.</p>
-
-<p><span class="bold">Cortex.</span> The cortex contains parenchyma and stone cells.</p>
-
-<p>The outer layer of the cortical parenchyma cells are variable
-in size and many of the cells contain deposits of calcium carbonate
-and dark cell contents; the inner parenchyma cells are
-larger and they are free of the dark-brown cell contents, but
-many of the cells contain deposits of calcium carbonate.</p>
-
-<p>Stone cells with thick, white, porous, and striated walls occur
-in among the cortical parenchyma cells.</p>
-
-<p><span class="bold">Phloem.</span> The phloem contains sieve cells, phloem, parenchyma,
-and bast fibres.</p>
-
-<p>The <span class="bold">sieve cells</span> are small and with thin, white, angled walls.</p>
-
-<p>The <span class="bold">phloem parenchyma</span> cells resemble the sieve cells, but
-they are larger.</p>
-
-<p>The <span class="bold">bast fibres</span> occur singly or in groups of two or three.
-The walls are white, non-porous, and non-striated.</p>
-
-<p><span class="bold">Cambium.</span> The cambium layer is composed of rectangularly
-shaped cells, which are frequently obliterated.</p>
-
-<p><span class="bold">Xylem.</span> The xylem contains vessels, wood parenchyma,
-and medullary rays.</p>
-
-<p>The <span class="bold">vessels</span> are large, rounded cells with thick walls.</p>
-
-<p><span class="pagenum" id="Page_227">[227]</span></p>
-
-<p>The wood parenchyma consists of thick-walled cells of irregular
-size and form.</p>
-
-<p>The <span class="bold">medullary rays</span> are tangentially elongated and rectangular
-in form.</p>
-
-<p><span class="bold">Pith parenchyma.</span> The pith parenchyma cells are rounded
-in outline and as large as the cortical parenchyma cells.</p>
-
-<h5 id="POWDERED_PINK_ROOT">POWDERED PINK ROOT</h5>
-
-<p>When the roots and rhizomes of spigelia are powdered (Plate
-93) they show the following structure:</p>
-
-<p>The epidermal cells are small and brownish on surface view,
-varying in size from 13 by 18 micromillimeters to 31 by 40
-micromillimeters. When associated with parenchyma they appear
-as black masses. The cortical parenchyma cells are rounded
-and vary in size from 23 by 26 micromillimeters to 37.5 by 90
-micromillimeters. Many of the cells from the root contain
-larger quantities of minute single rounded starch grains varying
-in size from 1 micromillimeter to 4 micromillimeters. The
-larger round single starch grains are found in both the cortical
-and pith parenchyma of the rhizome. They vary in size from
-5 micromillimeters to 18 micromillimeters. The conducting
-elements are pitted tracheids varying from 10 micromillimeters
-to 38 micromillimeters in diameter. A few pitted and annular
-vessels are also found. The only fibres occurring are found in
-the xylem. They are not a prominent feature of the powder,
-as their walls break up into minute fragments. The pith
-parenchyma varies in size from 13 by 19 micromillimeters to
-75 by 82.5 micromillimeters. It is in these cells that the largest
-starch grains occur.</p>
-
-<p>Distinguishing diagnostic characters of the powder:<br />
-<span class="pad1">1.</span> Parenchyma with starch.<br />
-<span class="pad1">2.</span> Dark masses of epidermal tissue.<br />
-<span class="pad1">3.</span> Spigelia should contain starch, and it should not contain
-cystoliths, stone cells, or long, white-walled bast fibres.</p>
-
-<h5 id="POWDERED_RUELLIA_ROOT">POWDERED RUELLIA ROOT</h5>
-
-<p>When the roots of ruellia root and rhizome are powdered
-(Plate 94) they show the following structure:</p>
-
-<p><span class="pagenum" id="Page_228">[228]</span></p>
-
-<div class="figcenter illowp52" id="plate93" style="max-width: 130.25em;">
-  <img class="w100 p1" src="images/plate93.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 93</span><br />
-<span class="smcap">Powdered Spigelia marylandica</span>, L.
-
-<div class="blockquotc">
-<p>1. Epidermis and cortical parenchyma. 2. Tracheids and fibres. 3. Parenchyma
-cells of the root containing the small starch grains, longitudinal view.
-4. Parenchyma of the rhizome containing the large starch grams, transverse
-view. 5. Tracheids. 6. Surface view of the epidermal cells. 7. Starch scattered
-through the field. 8 and 8´. Dark masses of epidermal and underlying tissue.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_229">[229]</span></p>
-
-<div class="figcenter illowp57" id="plate94" style="max-width: 131.3125em;">
-  <img class="w100 p1" src="images/plate94.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 94</span><br />
-<span class="smcap">Powdered Ruellia ciliosa</span>, Pursh.
-
-<div class="blockquotc">
-<p>1. Short, broad cystoliths from the rhizome, 1´. Long cystoliths from the
-root. 2 and 2´. Long, narrow, white-walled bast fibres. 3. Tracheal tissue
-from the xylem of the stem. 4. Root parenchyma. 5. Tracheal tissue from
-the xylem of the root. 6. Cortical parenchyma cells from the rhizome with
-short, broad cystoliths. 7 and 7´. Long, thick-walled sclerids from the root.
-8. Short, broad sclerids from the stem. 9. Pitted pith parenchyma from the
-stem with intercellular space. 10. Parenchyma of the root with sclerid and
-cystolith, longitudinal view.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_230">[230]</span></p>
-
-<p>The epidermal cells vary from 7.8 by 15.6 micromillimeters
-to 15.1 by 16.6 micromillimeters. The cell contents are dark
-and the walls are light. A few rows of the outer cortical parenchyma
-cells of both the rhizome and the root have dark cell
-contents and white walls. The dark contents disappear toward
-the phloem. The cortical cells vary from 13.6 by 14.3 micromillimeters
-to 89.5 by 90.9 micromillimeters. In the cortical
-parenchyma cells of the rhizome are found the short, broad
-cystoliths measuring up to 52 by 62 micromillimeters. In the
-corresponding cells of the root are found the long, narrow cystoliths
-which measure up to 68.4 by 187.2 micromillimeters.
-Scattered throughout the powder are seen three distinct types
-of sclerids (stone cells) which are associated with the cortical
-parenchyma of both the stem and the root. Most of them are
-found, however, in the roots. First, the short, broad stone
-cells from the stem basis have square ends; the walls vary from
-13 to 19.5 micromillimeters in thickness with branching pores
-which extend toward the adjacent cell. These sclerids vary in
-size from 52 by 54.6 micromillimeters to 45 by 130 micromillimeters.
-Secondly, the long stone cells from the root vary from
-32 by 96 micromillimeters to 45.5 by 542.5 micromillimeters
-with walls 16 micromillimeters thick. The width of the cell
-and the thickness of the wall vary but little throughout their
-entire length. The third type of stone cell also from the root
-has unequally thickened walls and the ends are square or blunt.
-A few long, narrow, colorless, thin-walled bast fibres also occur.
-They are 13 micromillimeters wide, with walls 3.9 micromillimeters
-thick. Annular spiral and pitted vessels are also found
-scattered throughout the powder.</p>
-
-<p>The diagnostic characters of the powder are:<br />
-<span class="pad1">1.</span> The short, broad, and long, narrow cystoliths.<br />
-<span class="pad1">2.</span> The short, broad, and long, narrow sclerids.<br />
-<span class="pad1">3.</span> The long, narrow, thin, white-walled bast fibres.</p>
-
-<p>In poke root, ipecac, sarsaparilla, and veratrum are raphides.
-In belladonna and horse-nettle roots are micro-crystals. In
-calumba, stillingea, krameria, licorice, scamony root are prisms.
-In saponaria, jalap, althea, spikenard, rumex, rhubarb are
-rosette crystals. In pleurisy roots both prisms and rosettes
-occur.</p>
-
-<p>In gentian, senega, symphytuns, lovage, parsley, inula,<span class="pagenum" id="Page_231">[231]</span>
-echinacea, angelica, burdock, and chicory no crystals of any
-kind occur. Root hairs occur in cross-sections of sarsaparilla
-root and false unicorn, but with these exceptions: root hairs do
-not occur on roots, because the younger part of the root with
-root hairs is not removed from the soil when the drug is collected.
-In sarsaparilla root there are several layers of hypodermal cells;
-in most roots there are no hypodermal cells. In the non-woody
-roots or the roots of herbs the parenchyma cells form the greater
-part of the tissues of the root. In ruellia root are stone cells;
-in spigelia root and many other roots there are no stone cells.
-In ruellia root are bast fibres; in spigelia, gentian, ipecac, chicory,
-dandelion, symphytum, and lovage no bast fibres occur. In
-all the woody roots there is a periderm consisting of typical
-cork cells, as in black haw; or stone cells, as in asclepias; or
-of a mixture of lifeless parenchyma, medullary rays, etc., as in
-Oregon grape root.</p>
-
-<p>Woody roots have a phellogen layer which is absent in the
-non-woody roots.</p>
-
-<p>The numbers of layers of cortical parenchyma differ in the
-same root according to its age, but for a given root there is a
-normal variation.</p>
-
-<p>The number of layers of cortical parenchyma in proportion
-to other cells is less in woody roots.</p>
-
-<p>In woody roots there is no endodermis. The cambium in these
-cases shows clearly between the phloem and the xylem part of
-the fibro-vascular bundle.</p>
-
-<p>In woody roots the wood fibres are well developed and form
-a large part of the root, and the medullary rays have pitted
-side and end walls.</p>
-
-<p>The description given above of ruellia root is not typical of
-all roots, but the structure represents the greater number of
-the elements that it is possible to find in a root. In many roots,
-for instance, there are no stone cells, in others no epidermis
-and no endodermis. In asclepias, aconite, and calumba stone
-cells occur. In symphytum, chicory, dandelion, burdock, elecampane,
-pyre thrum, gentian, and senega no stone cells occur. In
-aconite, althea, asclepias, belladonna, bryonia, columba, ipecac,
-jalap, krameria, sarsaparilla, scamony, stillingea, and rumex
-are characteristic starch grains. Symphytum, chicory, dandelion,<span class="pagenum" id="Page_232">[232]</span>
-burdock, elecampane, and pyrethrum contain inulin, but
-no starch. In saponaria, gentian, and senega neither starch
-nor inulin occurs.</p>
-
-<p>When studying roots the nature of the epidermis or the
-periderm must be considered, as also the number of layers of
-cortical parenchyma; the occurrence, distribution, and amount
-of stone cells when present; the presence or absence of the
-endodermis; the occurrence and structure of bast fibres when
-present; the nature of the cambium cells; the width and structure
-of the medullary rays, the size of the wood fibres and wood
-parenchyma, and the nature of the cell contents and the arrangement
-of the fibro-vascular bundle.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_233">[233]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_II">CHAPTER II<br />
-<span class="fs80">STEMS</span></h3>
-</div>
-
-<p>When studying stems it should first be determined whether
-they were derived from monocotyledonous or dicotyledonous
-plants. This fact is ascertained by determining the type of
-the fibro-vascular bundle. See Chapter XI. The next fact
-to determine is whether the stem is from an herb or from a woody
-plant. This fact is readily determined because herbaceous
-stems have a true epidermis, masses of collenchyma at the
-angles of the stem. The cortical cells contain chlorophyll, and
-the pith is very large. Woody stems have a corky layer, a
-phellogen layer, and the pith is very small except in the very
-young woody stems.</p>
-
-<p>Having determined these facts, a study should be made of
-the arrangement, form, structure, color, and the cell contents
-of the different cells in order to determine the species of plant
-from which the stem was obtained.</p>
-
-<h4 id="HERBACEOUS_STEMS">HERBACEOUS STEMS</h4>
-
-<p>The great variation in the structure of herbaceous stems is
-shown in the cross-sections of spigelia (Plate 95); in ruellia
-(Plate 96); in the charts of powdered genuine horehound,
-powdered spurious horehound, and in the chart of powdered
-insect flower stems.</p>
-
-<h5 id="CROSS-SECTION_SPIGELIA_STEM">CROSS-SECTION SPIGELIA STEM</h5>
-
-<p>Spigelia stem (Plate 95) has the following characteristic
-structure:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells are papillate.</p>
-
-<p><span class="bold">Cortex.</span> The cortical parenchyma cells consist of tangentially
-elongated cells which are oval in outline.</p>
-
-<p><span class="bold">Phloem.</span> The phloem consists of sieve cells, phloem parenchyma,
-and of bast fibres.</p>
-
-<p><span class="pagenum" id="Page_234">[234]</span></p>
-
-<div class="figcenter illowp50" id="plate95" style="max-width: 132em;">
-  <img class="w100 p1" src="images/plate95.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 95</span><br />
-<span class="smcap">Cross-Section of Stem of Spigelia marylandica</span>, L.
-
-<p>1. Papillate epidermis.     <span class="pad2h">4.</span> Phloem.    <span class="pad2"> 7.</span> Inner phloem.<br />
-<span class="pad1">2.</span> Cortical parenchyma.     <span class="pad2">5.</span> Cambium.    <span class="pad1">8.</span> Pith.<br />
-<span class="pad1">3.</span> Bast stereome.           <span class="pad4h">6.</span> Xylem.</p>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_235">[235]</span></p>
-
-<p>The <span class="bold">sieve cells</span> are small, and with thin, white, angled
-walls.</p>
-
-<p>The <span class="bold">phloem parenchyma</span> resembles the sieve cells, but they
-are larger.</p>
-
-<p>The bast fibres are rounded in outline and the walls are
-thick, white, non-porous, and non-striated.</p>
-
-<p><span class="bold">Cambium.</span> The cambium cells are rectangular in shape or
-the walls are collapsed and the cells indistinct.</p>
-
-<p><span class="bold">Xylem.</span> The xylem contains vessels, wood parenchyma,
-medullary rays. The vessels are small and angled, the walls
-are thick and white.</p>
-
-<p><span class="bold">Wood parenchyma.</span> The cells are variable in size and shape,
-and the walls are thick. The medullary ray cells are small,
-narrow, and tangentially elongated.</p>
-
-<p><span class="bold">Internal Phloem.</span> External to the pith parenchyma are
-isolated groups of internal phloem consisting of sieve cells.</p>
-
-<p><span class="bold">Pith Parenchyma.</span> The pith parenchyma cells are oval in
-form and irregularly placed. The cells contain small, simple
-starch grains.</p>
-
-<h5 id="RUELLIA_STEM">RUELLIA STEM</h5>
-
-<p>The cross-section of ruellia stem (Plate 96) is as follows:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells are variable in shape and
-very large. There are no cell contents.</p>
-
-<p><span class="bold">Cortex.</span> The cortex consists of collenchyma and parenchyma
-cells and stone cells.</p>
-
-<p>The <span class="bold">collenchyma cells</span> have very small, angled cavities and
-very thick walls. These cells make up the greater part of the
-cortex.</p>
-
-<p>The <span class="bold">cortical parenchyma</span> cells are variable in size and shape.
-The stone cells occur singly or in groups. The walls are thick,
-white, porous, and striated, and the central cavity is frequently
-quite large.</p>
-
-<p><span class="bold">Phloem.</span> The phloem contains sieve cells, phloem parenchyma,
-and bast fibres.</p>
-
-<p>The <span class="bold">sieve cells</span> have thin, white, angled walls.</p>
-
-<p>The <span class="bold">phloem parenchyma</span> cells are frequently tangentially
-elongated, otherwise they resemble the sieve cells.</p>
-
-<p>The <span class="bold">bast fibres</span> occur alone or in groups. The walls are
-thick, white and porous.</p>
-
-<p><span class="pagenum" id="Page_236">[236]</span></p>
-
-<div class="figcenter illowp51" id="plate96" style="max-width: 129.5625em;">
-  <img class="w100 p1" src="images/plate96.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 96</span><br />
-<span class="smcap">Cross-Section of Stem of Ruellia ciliosa</span>, Pursh.
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Collenchyma. 3. Parenchyma. 4. Sclerids. 5. Bast
-fibres. 6. Phloem. 7. Cambium cells. 8. Xylem. 10. Pith parenchyma.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_237">[237]</span></p>
-
-<p><span class="bold">Cambium.</span> The cambium cells are rectangular in shape
-and the walls are thin.</p>
-
-<p><span class="bold">Xylem.</span> The xylem contains vessels, wood parenchyma, and
-medullary rays.</p>
-
-<p>The <span class="bold">vessels</span> are large; the walls are thick, white, and angled.</p>
-
-<p>The <span class="bold">wood parenchyma</span> cells are variable in size and shape
-and the walls are angled.</p>
-
-<p>The <span class="bold">medullary ray cells</span> are radially elongated and rectangular
-in shape.</p>
-
-<p><span class="bold">Pith Parenchyma.</span> The pith parenchyma cells are large and
-rounded in shape.</p>
-
-<h5 id="POWDERED_HOREHOUND">POWDERED HOREHOUND</h5>
-
-<p>The structure of powdered horehound is shown in Chart 97.
-The epidermal cells of the leaf (1) are wavy in outline, the guard
-cells are elliptical, the stoma lens-shaped, the epidermis often
-showing hairy outgrowth as in the illustration. The epidermal
-cells of the petals (2) have irregularly thickened beaded walls.
-The non-glandular hairs from the calyx (3); the long, thin-walled,
-multicellular non-glandular twisted hairs (4) from the
-leaves and stems; long, thin-walled, unicellular hairs (5) from
-the tube of the corolla; the glandular hairs (6) with a one-celled
-stalk and with two secreting cells divided by vertical walls; the
-eight-celled glandular hair (7) as seen in surface and side view;
-the spiral and reticulated conducting cells (8); the thick, white-walled
-fibres from the stem (9); the pollen grains (10) with
-nearly smooth walls.</p>
-
-<p>The diagnostic elements of the U. S. P. horehound are the
-long, twisted, multicellular hairs (4), the glandular hairs (7),
-and the pollen grains (10).</p>
-
-<h5 id="POWDERED_SPURIOUS_HOREHOUND">POWDERED SPURIOUS HOREHOUND</h5>
-
-<p><ins class="corr" id="tn237" title="Transcriber’s Note—“Marrubium perigrinum, which is a related species of horehound” changed to “Marrubium peregrinum, which is a related species of horehound”.">Marrubium peregrinum, which is a related species of horehound</ins>
-and which is a common adulterant of horehound, has
-the following structure (Plate 98):</p>
-
-<p><span class="pagenum" id="Page_238">[238]</span></p>
-
-<div class="figcenter illowp53" id="plate97" style="max-width: 135.4375em;">
-  <img class="w100 p1" src="images/plate97.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 97</span><br />
-<span class="smcap">Powdered Horehound</span> (<i lang="la" xml:lang="la">Marrubium vulgare</i>, L).
-
-<div class="blockquotc">
-<p>1. Epidermis of leaf showing the wavy epidermal cells, stoma, and a
-clustered hair. 2. Surface view of the petal epidermis. 3. Non-glandular
-hair from the calyx or corolla. 4. Long, thin-walled, twisted, non-glandular
-hairs from the leaves and stem. 5. Unicellular non-glandular hair from the
-tube of the corolla. 6. Glandular hairs with a one-celled stalk and with two
-secreting cells divided by vertical walls. 7. Surface and side view of the
-eight-celled glandular hairs. 8. Conducting cells. 9. Fibres from the stem.
-10. Pollen grains.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_239">[239]</span></p>
-
-<div class="figcenter illowp53" id="plate98" style="max-width: 130.9375em;">
-  <img class="w100 p1" src="images/plate98.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 98</span><br />
-<span class="smcap">Spurious Horehound</span> (<i lang="la" xml:lang="la">Marrubium peregrinum</i>, L.)
-
-<div class="blockquotc">
-<p>1. Surface view of the leaf epidermis. 2. View of the petal epidermis.
-3. Non-glandular multicellular branched hair from the stem, leaves, or flowers
-with a few of the lower branches broken. 4. Broken pieces and branches from
-the compound hairs scattered throughout the field. 5. Unicellular glandular
-hair with a two-celled stalk. 6. Under-surface view of an eight-celled glandular
-hair. 7. Side view of eight-celled glandular hair. 8. Long, pointed,
-unicellular, non-glandular hair from the corolla, the wall irregularly thickened
-near the apex. 9. Fibres. 10. Pollen grains, 11. Conducting cells of leaf.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_240">[240]</span></p>
-
-<div class="figcenter illowp50" id="plate99" style="max-width: 131.625em;">
-  <img class="w100 p1" src="images/plate99.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 99</span><br />
-<span class="smcap">Powdered Insect Flower Stems</span> (<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i>,
-[Trev.], Vis.)
-
-<div class="blockquotc">
-<p>1. Surface view of epidermis.<br />
-<span class="pad1">2.</span> Cross-section of epidermis.<br />
-<span class="pad1">3.</span> Hairs.<br />
-<span class="pad1">4.</span> Fibres.<br />
-<span class="pad1">5.</span> Cross-section of fibres.<br />
-<span class="pad1">6.</span> Longitudinal view of pith parenchyma.<br />
-<span class="pad1">7.</span> Cross-section of pith parenchyma.<br />
-<span class="pad1">8.</span> Conducting cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_241">[241]</span></p>
-
-<p>The wavy leaf epidermis (1) with stoma; the beaded wall
-petal epidermis (2); the non-glandular, multicellular branched
-hairs (3) from the stem leaves or flowers; the broken pieces and
-branches of the compound hairs (4) scattered throughout the
-field; the glandular hairs (5) with a two-celled stalk; the eight-celled
-glandular hair (7) seen in surface view and a side view (8)
-of a similar hair; the long, pointed, unicellular non-glandular
-hair from the tube of the corolla, the wall irregularly thickened
-near the apex; the fibres (9) from the stem; the pollen grains
-(10) with prominent centrifugal projections; the conducting
-cells.</p>
-
-<p>The diagnostic elements of marrubium peregrinum are the
-multicellular branched hairs (3) which occur on all parts of the
-plant, usually much broken in the powder, with walls many
-times thicker than the walls of the hairs found in U. S. P. horehound;
-the pollen grains (10) with centrifugal projections and
-the stalked glandular hairs (5).</p>
-
-<h5 id="INSECT_FLOWER_STEMS">INSECT FLOWER STEMS</h5>
-
-<p>Insect flower stems are the chief adulterant of insect flowers.
-Until the passage of the insecticide law, it was a common practice
-to sell (for insect powder) a mixture of powdered stems and
-flowers. Since the passage of the law, the presence of the stems
-in a powder is supposed to be declared on the label. In spite
-of the penalties attached, their presence in a powder is frequently
-not declared, as evidenced by a microscopical examination of
-the insect powders obtained in the open market.</p>
-
-<p>The structure of powdered insect flower stems (Chart 99) is
-as follows:</p>
-
-<p>The epidermal cells of the stems are prominently marked
-with stoma and angled, striated wall cells (Fig. 1). On cross-section
-(Fig. 2) the stem is seen to be made up of epidermal
-cells with thick outer and thin side walls (Fig. 2). The T-shaped
-hairs (Fig. 3) are longer than those found on any other part of
-the plant. The fibres (Fig. 4) are the most characteristic part
-of the powder. They are elongated, and the walls are white
-and slightly porous and of nearly uniform thickness. They
-occur free in the field or in groups of two or more. The
-cross-section view of these fibres is shown in Fig. 5. The pith
-parenchyma (Fig. 6) is abundant and is composed of thick,
-porous-walled cells. On cross-section the cells are rounded
-and are separated by intercellular spaces. The conducting cells
-(Fig. 8) vary from spiral to reticulate.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_242">[242]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_III">CHAPTER III<br />
-<span class="fs80">WOODY STEMS</span></h3>
-</div>
-
-<h5 id="BUCHU_STEM">BUCHU STEM</h5>
-
-<p>The cross-section of a buchu stem (Plate C), 1.6 millimeters
-in diameter, shows a few of the epidermal cells modified into
-thick-walled, roughish, unicellular trichomes (1). The remaining
-epidermal cells have a thick, wavy outer wall (2). Beneath
-the epidermis are several rows of cortical parenchyma cells (3)
-which extend to the bast bundles and in which are found the
-secretory cavities with the thin-walled secretory cells (4). The
-bast fibres (5) occur in continuous bands, varying greatly in size;
-the walls are whitish and of variable thickness. Inside the
-bast fibres, the small irregular sieve cells (6) occur in groups,
-surrounded by the phloem parenchyma (8). The radially
-elongated cells of the medullary rays (7) extend outward from
-the xylem, increasing in number in the outer portions of the
-wood, and extending nearly to the bast fibres. No distinct
-cambium layer is visible. The conducting cells (9) occur
-throughout the xylem surrounded by the wood fibres and wood
-parenchyma (10). The latter is not very abundant in buchu.
-The medullary rays border on the conducting cells and extend
-outward to the phloem. The pith parenchyma cells are nearly
-circular in outline and often show a perforated end wall when
-a cell happens to be cut just above or below that point.</p>
-
-<h5 id="MATURE_BUCHU_STEM">MATURE BUCHU STEM</h5>
-
-<p>In Plate 101-A is shown the cork formation or secondary
-growth as seen in the older, larger buchu stems. The wavy
-epidermis (1), which is the primary epidermis and which has
-disappeared on many portions of the stem, has thin side walls
-and dark cell contents (2). Next to the epidermal cells occur
-several rows of peculiarly arched cork cells with thick, white
-outer walls (3) and reddish-brown cell contents (4). The cork
-cambium (5) is typical in form, and it has formed one or two
-layers of phelloderm cells (6) which have the same form as the
-cambium cells but with thicker walls. Next to the phelloderm
-occur the cortical parenchyma cells. The remaining structure
-of the mature stem is identical with that of Fig. 2.</p>
-
-<p><span class="pagenum" id="Page_243">[243]</span></p>
-
-<div class="figcenter illowp46" id="plate100" style="max-width: 38.75em;">
-  <img class="w100 p1" src="images/plate100.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 100</span><br />
-<span class="smcap">Cross-Section of Buchu Stems</span> <br />(<i lang="la" xml:lang="la">Barosma betulina</i> [Berg.], Barth, and Wendl.)
-
-<div class="blockquotc">
-<p>1. Hairs. 2. Wavy epidermis. 3. Cortical parenchyma. 4. Secretion
-cells and cavity. 5. Group of bast fibres. 6. Sieve cells. 7. Medullary rays.
-8. Phloem parenchyma. 9. Vessels. 10. Wood fibres, and wood parenchyma.
-11. Pith parenchyma.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_244">[244]</span></p>
-
-<div class="figcenter illowp53" id="plate101" style="max-width: 44.75em;">
-  <img class="w100 p1" src="images/plate101.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 101</span>
-
-<div class="blockquotc">
-<p><em>A.</em> Cross-section of buchu stem (<i lang="la" xml:lang="la">Barosma betulina</i> [Berg.], Barth. and
-Wendl.). 1, Outer wall of epidermis; 2, Cell cavity of epidermal cell; 3, Wall
-of cork cell; 4, Cavity of cork cell; 5, Phellogen layer; 6, Divided phellogen
-cell changing into a cortical parenchyma cell; 7, Cortical parenchyma cell.<br />
-<span class="pad1"><em>B.</em></span> Cross-section of leptandra rhizome (<i lang="la" xml:lang="la">Leptandra virginica</i> [L.], Nutt.).
-1, Parenchyma cells undergoing change in the composition of their walls; 2, A
-break in the epidermal tissue; 3, Parenchyma cells undergoing division.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_245">[245]</span></p>
-
-<h5 id="POWDERED_BUCHU_STEM">POWDERED BUCHU STEM</h5>
-
-<p>Powdered buchu stem (Plate 102) has many striking features
-which make it easy of identification when mixed with buchu
-leaves. A few unicellular, rough, thick, white-walled trichomes
-(1) occur distributed throughout the field. They are straight
-or slightly curved and vary in length from 40 to 100 microns;
-in thickness at the bast they measure from 10 to 22 microns.
-The central cavity varies greatly, and in some trichomes seems
-to have disappeared entirely. The epidermal cells (2) are very
-characteristic, occurring singly or in groups of two or more.
-The cells from the older stems often appear reddish brown by
-transmitted light, while the epidermal cells from the younger
-stems appear whitish opaque (porcelain-like). They are usually
-six-sided and angular in outline. The cortical parenchyma
-cells (3) on transverse view have a rounded cell cavity and
-intercellular spaces between the walls. The double walls vary
-in thickness, the greatest thickness being about 9 microns. The
-parenchyma cells (3) on longitudinal view show square ends
-and often contain sphæro-crystalline masses of hesperidin. The
-thin-walled sieve cells and the surrounding cells are scarcely
-ever seen in the powder. The white-walled pointed stereomes
-(4) are a characteristic feature of the powder; they vary greatly
-in length, in diameter and in the thickness of their walls. In
-a number eighty powder the fibres are mostly broken. The
-greatest length of the unbroken fibres is 1.25 microns. The
-thickest wall measured 5 microns and the greatest observed
-width was 25 microns. The spiral reticulate and scalariform
-thickened conducting cells occur scattered throughout the
-powder. The reticulate and scalariform cells usually occur with
-wood fibres. It is an interesting fact that the spiral thickening
-in conducting cells is usually separate from the side wall and
-nearly always appears as indicated at 5. An occasional rosette
-crystal of calcium oxalate (6) is seen in the field. The wood
-parenchyma (7), which makes up a very small percentage of
-the xylem, is not readily found in the powder. The pith parenchyma
-cells (8) have thick, porous side walls and perforated side
-walls. The wood fibres (9) usually occur in masses surrounding
-the conducting cells; when occurring singly, the oblique pores
-readily distinguish them from the bast fibres.</p>
-
-<p><span class="pagenum" id="Page_246">[246]</span></p>
-
-<div class="figcenter illowp53" id="plate102" style="max-width: 44.9375em;">
-  <img class="w100 p1" src="images/plate102.jpg" alt="" />
-  <div class="caption"><span class="bold">PLATE 102</span><br />
-<span class="smcap">Powdered Buchu Stems</span> <br />(<i lang="la" xml:lang="la">Barosma betulina</i> [Berg.], Barth. and Wendl.).
-
-<div class="blockquotc">
-<p>1. Hairs. 2. Epidermal cells, the larger pieces reddish-brown; the smaller
-aggregations white. 3. Transverse cortical parenchyma. 3’ Longitudinal
-cortical parenchyma with sphæro crystalline masses of hesperidin. 4. Bast
-fibres. 5. Spiral, sclariform, and reticulate vessels. 6. Rosette crystals of
-calcium oxalate. 7. Wood parenchyma. 8. Pith parenchyma with porous
-side and end walls. 9. Wood fibres.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_247">[247]</span></p>
-
-<p>The diagnostic elements of powdered buchu stems are:</p>
-
-<p>First, trichomes; secondly, reddish-brown and white-angled
-epidermal cells; thirdly, the long, white bast fibres.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_248">[248]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_IV">CHAPTER IV<br />
-<span class="fs80">BARKS</span></h3>
-</div>
-
-<p>Barks are all obtained from dicotyledonous plants. In
-studying barks there should be ascertained the thickness, arrangement,
-form, structure, color, and cell contents of the cells
-occurring in the <em>outer</em>, <em>middle</em>, and <em>inner</em> barks.</p>
-
-<p>The outer bark includes the cork cells and the phellogen
-layer. The middle bark includes all the cells occurring between
-the phellogen layer and the beginning of the medullary rays.
-The inner bark includes the medullary ray cells and all cells
-associated with them. The plan of structure of all barks is
-similar, but in each species of plant the structure of the bark
-is uniform and characteristic for the species.</p>
-
-<p>A great number of drugs consist of the bark of woody plants;
-for this reason the bark is considered in a separate chapter from
-the stem.</p>
-
-<h5 id="WHITE_PINE_BARK">WHITE PINE BARK</h5>
-
-<p>The cross-section of white pine bark (Plate 103) has the
-following structure:</p>
-
-<p><span class="bold">Outer Bark.</span> The periderm consists of several layers of
-reddish-brown cork cells (1) which are narrow, elongated, and
-with thin walls.</p>
-
-<p><span class="bold">Middle Bark.</span> The cells forming the middle bark are parenchyma
-and secretion cells.</p>
-
-<p>The <span class="bold">parenchyma cells</span> vary greatly in size, form, and thickness
-of the walls. The cells beneath the cork cells and around
-the secretion cells are tangentially elongated and oval in shape,
-while the other parenchyma cells are more irregular in shape.</p>
-
-<p>The secretion cells are arranged around the schizogenous
-secretion cavities. The cells are tangentially elongated, and the
-walls, which are slightly papillate, are white.</p>
-
-<p><span class="bold">Inner Bark.</span> The cells forming the inner bark are medullary
-rays, parenchyma, sieve cells, and storage cavities.</p>
-
-<p><span class="pagenum" id="Page_249">[249]</span></p>
-
-<div class="figcenter illowp51" id="plate103" style="max-width: 42.625em;">
-  <img class="w100 p1" src="images/plate103.jpg" alt="" />
-  <div class="caption">PLATE 103<br />
-<span class="smcap">Cross-Section of Unrossed White Pine Bark</span> (<i lang="la" xml:lang="la">Pinus strobus</i>, L.)
-
-<div class="blockquotc">
-<p>1. Cork cells of the epidermis. 2. Parenchyma cells filled with chlorophyl.
-3. Intercellular space. 4. Secretion cavity with resin. 5. Secretion cells.
-6, One or more circles of parenchyma filled with chlorophyl. 7. Parenchyma.
-8. Medullary rays. 9. Sieve cells. 10. Storage cavities.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_250">[250]</span></p>
-
-<p>The <span class="bold">medullary rays</span> form wavy lines. The medullary ray
-cells are radially elongated, rectangular in shape, and they contain
-granular cell contents. The sieve cells are either square
-or rectangular in shape. The walls are thin and white. The
-storage cavities are either filled with starch or with prisms
-and tannin.</p>
-
-<h5 id="POWDERED_WHITE_PINE_BARK">POWDERED WHITE PINE BARK</h5>
-
-<p>White pine bark (Plate 104) when powdered shows the
-following characteristic elements:</p>
-
-<p>The microscopic structure of a powdered white pine is as
-follows: The epidermis (1) consists of reddish-brown masses,
-irregular in outline. The outer parenchyma cells are of a bright-green
-color, owing to the presence of chlorophyll. (The above
-elements are not usually found in the rossed bark.) The parenchyma
-(3) with starch usually occurs in longitudinal sections
-accompanied with sieve cells. Often the tissue separates transversely,
-showing the medullary rays (4) with their granular cell
-contents (9) and the inner parenchyma cells filled with starch
-and the surrounding sieve cells.</p>
-
-<p>The crystals are nearly perfect cubes and occur singly (5)
-or in groups (6). On the longitudinal section of the bark the
-crystals occur in parenchyma cells surrounded by a reddish cell
-content and form parallel rows which are very characteristic.
-The resin occurs either as white, angled fragments (7) in a water
-mount, or as globular mass (8) or as reddish-brown pieces (10).
-The starch is very abundant and is distributed through the
-field. The diagnostic grain is lens-shaped, with a cleft hilum,
-which is nearly straight, or slightly curved, and runs parallel
-to the long diameter of the grain. The addition of ferric
-chlorid T. S. will show the presence of tannin by forming a
-dark coloration. The identification of the starch is facilitated
-by the addition of a weak Lugol’s solution, which imparts a
-blue coloration to the starch grain.</p>
-
-<p>The form, amount, and distribution of the cells composing
-the bark differ greatly in different plants.</p>
-
-<p>In cramp bark the cork and phellogen cells are very large,
-while in cascara sagrada the phellogen and the cork cells are
-very small.</p>
-
-<p><span class="pagenum" id="Page_251">[251]</span></p>
-
-<div class="figcenter illowp52" id="plate104" style="max-width: 43.625em;">
-  <img class="w100 p1" src="images/plate104.jpg" alt="" />
-  <div class="caption">PLATE 104<br />
-<span class="smcap">Powdered White Pine Bark</span> (<i lang="la" xml:lang="la">Pinus strobus</i>, L.)
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Parenchyma cells. 3. Parenchyma with starch. 4.
-Medullary rays. 5. Solitary crystals. 6. Solitary crystals and tannin. 7, 8
-and 10. Resin masses. 9. Starch.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_252">[252]</span></p>
-
-<p>In canella alba bark the periderm is composed of stone cell
-cork or stone cells arranged in superimposed rows, which
-form the outer layers of the bark.</p>
-
-<p>In white oak and most barks from woody trees the periderm
-consists of lifeless parenchyma, medullary rays, sieve cells,
-bast fibres, and in some cases stone cells and of phellogen
-cells.</p>
-
-<p>In young wild cherry, cascara sagrada, and frangula are
-several layers of tangentially elongated collenchyma cells with
-chlorophyll. In the older barks of the above and in many
-other barks no collenchyma cells occur.</p>
-
-<p>In cramp bark and in tulip tree bark the outer layers of the
-cortical parenchyma cells are beaded. In most barks there is
-no beaded walled parenchyma. The outer layers of most
-cortical parenchyma cells are tangentially elongated while the
-inner parenchyma cells are mostly circular in outline.</p>
-
-<p>In white oak, cascara sagrada and prickly ash are groups
-of stone cells; in the cinnamon barks are bands of stone cells;
-in cinchona bark are isolated stone cells. In cramp bark,
-mezerum, elm, and white pine bark no stone cells occur.</p>
-
-<p>In frangula, cascara sagrada, cocillina, cinnamon, cinchona,
-sassafras, and wild cherry barks the bast fibres occur in groups.
-In frangula, cascara sagrada, and cocillina the bast fibres are
-surrounded by crystal cells with crystals.</p>
-
-<p>In sassafras bark mucilage cells occur. In canella alba,
-white pine, and sassafras barks secretion cells occur; but in
-most barks no secretion cells occur.</p>
-
-<p>In sassafras bark the medullary ray cells are nearly as broad
-as long; in cramp bark they are elongated and oval in shape.
-In cascara sagrada, as in most barks, the cells are longer than
-broad and rectangular in shape.</p>
-
-<p>In cascara sagrada the sieve cells are very large; in granatum
-bark the sieve cells are very small.</p>
-
-<p>In cassia cinnamon and in canella alba bark the walls of the
-sieve cells have collapsed, with the result that the sieve cells
-have become partly obliterated.</p>
-
-<p>In witch-hazel, mountain maple, willow, and black walnut
-are found prisms; in cramp bark, black haw, wahoo, pomegranate,
-and cotton root bark are found rosette crystals; in<span class="pagenum" id="Page_253">[253]</span>
-the cinnamon barks are found raphides; in cinchona bark,
-micro-crystals.</p>
-
-<p>In cocillina, frangula, cascara sagrada, white oak, poplar
-and Jamaica dogwood barks are found crystal-bearing fibres
-(Plates 19 and 20).</p>
-
-<p>When studying barks we must consider the kind, structure,
-and amount of the periderm; the nature of the phellogen; the
-nature and amount of the cortical parenchyma; the occurrence,
-distribution, and amount of stone cells, when present; the
-occurrence and structure of the bast fibres; the presence or
-absence of secretion cells; the width, distribution, and structure
-of the medullary rays.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_254">[254]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_V">CHAPTER V<br />
-<span class="fs80">WOODS</span></h3>
-</div>
-
-<p>Quite a number of drugs consist of the <span class="bold">wood</span> of woody plants;
-such drugs are quassia, red saunders, white sandalwood, and
-guaiac.</p>
-
-<p>When studying woods it is necessary to observe the cross,
-tangential, and radial sections. Such sections of quassia are
-shown in Plates 105, 106, and 107. When studying these sections
-it should be remembered that while the types of cells forming
-quassia wood are similar to the cells forming other woods,
-still their structure, arrangement, and amount will vary in a
-recognizable way in the different woods.</p>
-
-<h5 id="CROSS-SECTION_QUASSIA">CROSS-SECTION QUASSIA</h5>
-
-<p>Plate 105 is a cross-section of quassia. It has the following
-structure:</p>
-
-<p><span class="bold">Vessels.</span> The vessels occur singly or in groups of two to
-eight cells. The cells are variable in size and shape. The
-walls are yellowish white and porous.</p>
-
-<p><span class="bold">Medullary Rays.</span> The medullary rays vary from one to five
-cells in width.</p>
-
-<p>The <span class="bold">medullary ray cells</span> are radially elongated and the walls
-are strongly porous.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells have thin,
-yellowish-white, angled walls.</p>
-
-<p><span class="bold">Wood Fibres.</span> The wood fibres have thick, yellowish-white,
-angled walls. These cells are smaller in diameter than the
-wood parenchyma cells.</p>
-
-<h5 id="RADIAL_SECTION_QUASSIA">RADIAL SECTION QUASSIA</h5>
-
-<p>The radial section of quassia (Plate 107) is as follows:</p>
-
-<p><span class="bold">Vessels.</span> The vessels appear as in the tangential section.</p>
-
-<p><span class="bold">Medullary rays.</span> The medullary rays vary from ten to
-twenty cells in height according to the part of the medullary
-ray bundle cut across.</p>
-
-<p><span class="pagenum" id="Page_255">[255]</span></p>
-
-<div class="figcenter illowp57" id="plate105" style="max-width: 48.1875em;">
-  <img class="w100 p1" src="images/plate105.jpg" alt="" />
-  <div class="caption">PLATE 105<br />
-<span class="smcap">Cross-Section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)
-
-<div class="blockquotc">
-<p class="noindent">1. Vessels.<br />
-2. Medullary rays.<br />
-3. Wood parenchyma.<br />
-4. Wood fibres.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_256">[256]</span></p>
-
-<div class="figcenter illowp46" id="plate106" style="max-width: 38.5em;">
-  <img class="w100 p1" src="images/plate106.jpg" alt="" />
-  <div class="caption">PLATE 106<br />
-<span class="smcap">Tangential Section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)
-
-<div class="blockquotc">
-<p>1. Vessel. 2. Wood parenchyma. 3. Wood fibre. 4. End wall of medullary
-ray cell. 5. Medullary ray bundle.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_257">[257]</span></p>
-
-<div class="figcenter illowp93" id="plate107" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate107.jpg" alt="" />
-  <div class="caption">PLATE 107<br />
-<span class="smcap">Radial Section of Quassia Wood</span> (<i lang="la" xml:lang="la">Picræna excelsa</i> [Sw.], Lindl.)
-
-<div class="blockquotc">
-<p class="noindent">1. Showing the height and length of the medullary rays and cells.<br />
-2. Cells with starch.<br />
-3. Wood parenchyma and wood fibres.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_258">[258]</span></p>
-
-<p>The <span class="bold">medullary ray cells</span> exhibit their height and length.
-The walls of the cells are yellowish white and strongly
-porous.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells have
-yellowish, thin walls and blunt end walls.</p>
-
-<p><span class="bold">Wood Fibres.</span> The wood fibres have thick, yellowish-white
-walls, and the end of the cells are strongly tapering.</p>
-
-<h5 id="TANGENTIAL_SECTION_QUASSIA">TANGENTIAL SECTION QUASSIA</h5>
-
-<p>The tangential section of quassia (Plate 106) shows the
-following structure:</p>
-
-<p><span class="bold">Vessels.</span> The vessels are very long and broad and the
-yellow walls are marked with clearly defined pits.</p>
-
-<p><span class="bold">Medullary Rays.</span> The tangential section shows the cross-section
-of the medullary ray bundle and the cross-section of
-the medullary ray cell.</p>
-
-<p>The <span class="bold">medullary ray bundle</span> varies in width from one to five
-cells. The ends of the bundles are always one cell in width,
-while the central part of the bundle is frequently five cells
-in width.</p>
-
-<p>The <span class="bold">medullary ray cell</span> varies in size, structure, and shape
-according to the part of the cell cut across. The cells cut
-across the centre show hollow spaces, but the cells cut just
-above or below the end wall show a strongly pitted surface.
-The cells forming the end of the bundle are larger than the cells
-forming the centre of the bundle.</p>
-
-<p><span class="bold">Wood Parenchyma.</span> The wood parenchyma cells are greatly
-elongated and the walls are thin and yellowish white. The
-ends of the cells are blunt.</p>
-
-<p><span class="bold">Wood Fibres.</span> The wood fibres are elongated, the walls
-are thick and the cells are strongly tapering.</p>
-
-<p>In quassia, white sandalwood, red sandalwood, and guaiac
-wood are characteristic crystals.</p>
-
-<p>In quassia the vessels are finely pitted, yellowish, and distinct;
-in white sandalwood the vessels are coarsely and sparingly
-pitted and white translucent; in red saunders the vessels are
-coarsely pitted, bright red and distinct.</p>
-
-<p><span class="pagenum" id="Page_259">[259]</span></p>
-
-<p>When studying woods we must consider the width of the
-medullary rays, the structure and cell contents of the medullary
-ray cells; the structure, color, and cell contents of the wood
-parenchyma; also the wood fibres.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_260">[260]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_VI">CHAPTER VI<br />
-<span class="fs80">LEAVES</span></h3>
-</div>
-
-<p>Leaves collectively constitute the greatest manufacturing
-plant in the world. Most of the food, clothing, and medicine
-used by man is formed as a result of the work of the leaf. The
-cell contents, structure, and arrangement of the different cells
-of the leaf differ in a marked degree from the cell contents,
-structure, and arrangement of the cells in the other organs of
-the plant. This accounts for the presence of the large amount
-of chlorophyll in the leaf, the presence of stomata, and the
-peculiar arrangement of the cells.</p>
-
-<p>It should be ascertained if the stomata are above, even with,
-or below the epidermis; the nature of the epidermal cells, and,
-when present, the nature of the hypodermal cells; the number of
-layers of palisade parenchyma and whether it is present on
-both surfaces of the leaf, and the nature of the outgrowths from
-the epidermal cells.</p>
-
-<h5 id="KLIP_BUCHU">KLIP BUCHU</h5>
-
-<p>The cross-section of klip buchu (Plate 108) has the following
-structure:</p>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells of klip buchu are modified
-to form papillæ, the walls are yellowish white, and the papillate
-portion of the cell is nearly solid.</p>
-
-<p><span class="bold">Hypodermis.</span> The hypodermal cells are never intact because
-the mucilage contained in the cells swells when placed in water
-and breaks the thin side walls.</p>
-
-<p><span class="bold">Upper Palisade Parenchyma.</span> The palisade parenchyma is
-two layers in thickness. The cells of the outer layer are greatly
-elongated and are packed with chlorophyll. The inner layer
-of palisade cells is more irregular, and the cells are much shorter
-than the cells of the outer palisade layer.</p>
-
-<p><span class="pagenum" id="Page_261">[261]</span></p>
-
-<div class="figcenter illowp61" id="plate108" style="max-width: 51.1875em;">
-  <img class="w100 p1" src="images/plate108.jpg" alt="" />
-  <div class="caption">PLATE 108<br />
-<span class="smcap">Cross-Section of Klip Buchu just over the Vein</span>
-
-<div class="blockquotc">
-<p class="noindent"><em>A.</em> Papillate upper epidermis.<br />
-<em>B.</em> Hypodermal cells with broken side walls, due to expansion of mucilage<br />
-contents.<br />
-<em>C.</em> Palisade cells, showing two cells filled with chlorophyll.<br />
-<em>D.</em> Palisade like mesophyll.<br />
-<em>E.</em> Endodermis.<br />
-<em>F.</em> Vascular strand of vein.<br />
-<em>G.</em> Conducting cells with spirally thickened walls.<br />
-<em>H.</em> Characteristic leaf mesophyll.<br />
-<em>I.</em> Short, thick palisade cells on the under side of leaf, just under the vein.<br />
-<em>J.</em> Under hypodermal cells.<br />
-<em>K.</em> Papillate under epidermis.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_262">[262]</span></p>
-
-<p><span class="bold">Spongy Parenchyma.</span> The spongy parenchyma cells are
-branched; therefore, large intercellular spaces occur between
-the cells.</p>
-
-<p><span class="bold">Under Palisade Parenchyma.</span> The palisade cells of the
-under epidermis are short and broad, and they contain fewer
-chlorophyll grains than the upper palisade cells of the upper
-epidermis. These cells occur only under the veins.</p>
-
-<p><span class="bold">Under Hypodermis.</span> The under hypodermal cells are shorter
-and broader than the upper hypodermal cells.</p>
-
-<p><span class="bold">Under Epidermis.</span> The under epidermal cells are modified
-to form papillæ which are similar to the papillæ of the upper
-epidermis.</p>
-
-<p><span class="bold">Fibro-Vascular Bundle.</span> The cells composing the vascular
-bundle are sieve cells, vessels, and fibres.</p>
-
-<p>The <span class="bold">sieve cells</span> are small and the walls are white and
-angled.</p>
-
-<p>The <span class="bold">vessels</span> have thick, white, angled walls.</p>
-
-<p>The <span class="bold">bast fibres</span> are rounded in outline and the walls are thick
-and white.</p>
-
-<p><span class="bold">Endodermis.</span> The endodermal cells encircle the fibro-vascular
-bundles. The cells are large, thin-walled, and oval in shape.</p>
-
-<p><span class="bold">Secretion Cells.</span> Near the edges of the leaf are schizogenous
-secretion cavities surrounded by thin-walled secretion
-cells.</p>
-
-<h5 id="POWDERED_KLIP_BUCHU">POWDERED KLIP BUCHU</h5>
-
-<p>When the leaf is powdered (Plate 109), the cells are quite
-as characteristic in appearance. The upper epidermal cells
-(1) have thick-beaded, yellowish-white walls and papillate outer
-walls. No stomata occur on the upper surface. The under
-epidermis (2) with numerous stomata, is surrounded by the
-characteristic guard cells. The end walls are beaded as on the
-upper surface. The palisade cells (3) appear as in the cross-section.
-The conducting cells (4 and 4) are of the spiral and
-pitted type. The papillæ (5 and 5) are very abundant in the
-powder and very characteristic. The fragments of the epidermis
-(6) are also abundant. The mesophyll (7) is characteristic, as
-it retains its form when powdered. The fibres (8) are usually
-associated with the conducting cells; occasionally they are
-found free as in the illustration.</p>
-
-<p><span class="pagenum" id="Page_263">[263]</span></p>
-
-<div class="figcenter illowp56" id="plate109" style="max-width: 47.0625em;">
-  <img class="w100 p1" src="images/plate109.jpg" alt="" />
-  <div class="caption">PLATE 109<br />
-<span class="smcap">Powdered Klip Buchu</span>
-
-<div class="blockquotc">
-<p>1. Upper epidermis. 2. Under epidermis. 3. Palisade cells with chlorophyll.
-4 and 4. Conducting cells. 5 and 5. Papillæ. 6. Fragments of the
-epidermis. 7. Mesophyll. 8. Fibres.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_264">[264]</span></p>
-
-<h5 id="MOUNTAIN_LAUREL">MOUNTAIN LAUREL</h5>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells of mountain laurel are occasionally
-modified, as unicellular hairs (Plate 110, Fig. 1),
-particularly in the region of the veins. The ordinary epidermal
-cells have thick outer walls and thin inner walls. Beneath
-many of the epidermal cells are large air-spaces.</p>
-
-<p><span class="bold">Upper Palisade Parenchyma.</span> The palisade parenchyma
-vary from four to five layers. The inner palisade cells are
-shorter and broader than the outer layer of cells.</p>
-
-<p><span class="bold">Parenchyma.</span> The parenchyma cells (Fig. 4) are rounded
-in form and they are arranged in the form of columns which are
-one cell in thickness above, but two to three cells in thickness
-near the under epidermis. Between each chain of cells is a
-larger intercellular space (Fig. 6). In a few of the cells are large
-rosette crystals.</p>
-
-<p><span class="bold">Under Epidermis.</span> The under epidermal cells are uniformly
-smaller than the upper epidermal cells.</p>
-
-<p>It is thus seen that mountain laurel leaf has no hypodermal
-cells; no spongy parenchyma; no under palisade cells; no under
-hypodermal cells, and no secretion cavities.</p>
-
-<h5 id="TRAILING_ARBUTUS">TRAILING ARBUTUS</h5>
-
-<p><span class="bold">Epidermis.</span> The epidermal cells of the trailing arbutus
-(Plate 111, Fig. 2) are variable in size. Many of the cells are
-modified, as guard cells (Fig. 1).</p>
-
-<p><span class="bold">Parenchyma.</span> The parenchyma cells are round and they
-are compactly arranged (Fig. 3) on the upper side of the leaf,
-but on the under side they are arranged in round, small, intercellular
-spaces (Fig. 5). In some of the intercellular spaces are
-rosette crystals (Fig. 7).</p>
-
-<p><span class="bold">Under Epidermis.</span> The under epidermal cells are smaller
-than the upper epidermal cells.</p>
-
-<p>It will be seen that the structure of trailing arbutus leaf is
-very simple and that its structure is different from that of klip
-buchu and mountain laurel.</p>
-
-<p>The structure of powdered leaves is very variable, yet characteristic
-for a given species. The leaves from the insect flower
-plant are collected with the stems, and ground and sold as a
-substitute for insect flowers. These leaves, when powdered,
-show the following structure (Plate 112):</p>
-
-<p><span class="pagenum" id="Page_265">[265]</span></p>
-
-<div class="figcenter illowp65" id="plate110" style="max-width: 54.5625em;">
-  <img class="w100 p1" src="images/plate110.jpg" alt="" />
-  <div class="caption">PLATE 110<br />
-<span class="smcap">Cross-Section Mountain Laurel</span> (<i lang="la" xml:lang="la">Kalmia latifolia</i>, L.)
-
-<div class="blockquotc">
-<p>1. Hair. 2. Epidermis. 3. Palisade parenchyma. 4. Parenchyma. 5.
-Under epidermis. 6. Intercellular space. 7. Rosette crystal. 8. Chlorophyll.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_266">[266]</span></p>
-
-<div class="figcenter illowp100" id="plate111" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate111.jpg" alt="" />
-  <div class="caption">PLATE 111<br />
-<span class="smcap">Cross-Section Trailing Arbutus Leaf</span> (<i lang="la" xml:lang="la">Epigæa repens</i>, L.)
-
-<div class="blockquotc">
- <p>1. Stomata. 2. Epidermis. 3. Parenchyma. 4. Cell with chlorophyll.
-5. Intercellular space. 6. Under epidermis. 7. Rosette crystal.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_267">[267]</span></p>
-
-<p>Both the upper and lower epidermis have stomata (Figs.
-1 and 2), but they differ in that the surrounding cells of the
-upper epidermis are wavy, while the corresponding cells of the
-under epidermis are similar, though the under epidermis has
-many attached hairs (Figs. 3 and 4). The T-shaped hairs form
-the most abundant element of the powder. They are similar
-in structure to those found on the scales and stem. Fragments
-of the mesophyll have round cells and contain chlorophyll
-(Fig. 6). The conducting cells are spiral or reticulate.</p>
-
-<p>The different cells of the leaf differ greatly in structure, in
-amount, and in arrangement. In uva-ursi, boldus, pilocarpus,
-eucalyptus, and chimaphila leaves the outer walls of the epidermal
-cell is very thick. In uva-ursi leaves this thick wall appears
-bluish green when viewed under low power of the microscope.</p>
-
-<p>In belladonna, stramonium, henbane, peppermint, spearmint,
-digitalis, and horehound, the outer wall of the epidermal
-cells is thin.</p>
-
-<p>In witch-hazel, stramonium, coca, phytolacca, and peppermint
-there is a single layer of palisade parenchyma on the
-upper surface only of the leaf.</p>
-
-<p>In senna there is one layer of palisade parenchyma on
-the upper and one layer on the under side of the leaf. In
-matico and tea leaves there are two layers of spongy parenchyma
-on the upper side of the leaf.</p>
-
-<p>In chestnut leaves there are three layers of palisade parenchyma
-on the upper side of the leaf.</p>
-
-<p>In eucalyptus leaves the entire central part of the leaf,
-with the exception of the secretion cells and fibro-vascular
-bundle, is made up of the palisade parenchyma.</p>
-
-<p>In some leaves no palisade parenchyma occurs. Trailing
-arbutus (Plate 111) is an example of such a leaf.</p>
-
-<p>In stramonium leaves the spongy parenchyma is strongly
-branched; in mountain laurel the spongy parenchyma is
-mostly non-branched and circular in form, as in trailing arbutus
-(Plate 111, Fig. 3), and as occurs in the midrib portion of most
-leaves.</p>
-
-<p><span class="pagenum" id="Page_268">[268]</span></p>
-
-<div class="figcenter illowp50" id="plate112" style="max-width: 42.1875em;">
-  <img class="w100 p1" src="images/plate112.jpg" alt="" />
-  <div class="caption">PLATE 112<br />
-<span class="smcap">Powdered Insect Flower Leaves</span><br />
-(<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i> [Trev.], Vis.)
-
-<div class="blockquotc">
-<p>1. Upper epidermis. 2. Under epidermis showing stoma and hair scar.
-3. Cross-section of under epidermis with attached hair. 4. Cross-section of
-upper epidermis. 5. Hairs. 6. Mesophyll with chlorophyll bodies. 7. Conducting
-cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_269">[269]</span></p>
-
-<p>In stramonium and chestnut are found rosette crystals.
-In henbane, coca, and senna are found prisms. In belladonna,
-scapola, and tobacco leaves are found micro-crystals.
-In most leaves no crystals occur. In witch-hazel and tea
-leaves stone cells occur, but in most leaves there are no stone
-cells. In eucalyptus, thyme, jaborandi, buchu, rosemary, and
-white pine leaves are secretion cells; while in belladonna,
-stramonium cells occur. In senna and coca leaves are crystal-bearing
-fibres; most leaves do not have crystal-bearing fibres.</p>
-
-<p>In chimaphila and uva-ursi there are no outgrowths from
-the epidermal cells.</p>
-
-<p>In senna, witch-hazel, chestnut, and coca, numerous non-glandular
-hairs occur on the epidermis. In tobacco, belladonna,
-henbane, pennyroyal, peppermint, and spearmint both glandular
-and non-glandular hairs occur on the epidermis.</p>
-
-<p>When studying leaves there should be considered the absence
-or presence of outgrowths and their nature; the nature of
-the epidermis and, when present, the number of layers of the
-hypodermis; the nature of the stoma, whether raised above,
-even with, or below the level of the epidermis; the number of
-layers, and the distribution, when present, of the palisade
-parenchyma; the form and amount of the spongy parenchyma;
-the absence or presence of secretion cells; the nature and form
-of the fibro-vascular bundles, and the nature and amount of
-the organic and inorganic cell contents.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_270">[270]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_VII">CHAPTER VII<br />
-<span class="fs80">FLOWERS</span></h3>
-</div>
-
-<p>The histological structure of flowers is readily seen in the
-powder; therefore, in studying flowers, it is not necessary to
-section the various parts. Each part of the flower should be
-isolated and powdered separately and each separated part
-studied. In each case the powders will contain surface, cross-,
-and radial sections of the parts powdered. While studying
-flowers, special attention should be given to the pollen grains,
-to the papillæ of the petals, to the papillæ of the stigma, and,
-in certain flowers, to the style tissue. In the composite flowers
-special attention should also be given to the involucre scales,
-to the scales of receptacle, and, when present, to the pappus.
-In addition, attention must be given to secretion cavities, as
-in cloves.</p>
-
-<h5 id="POLLEN_GRAINS">POLLEN GRAINS</h5>
-
-<p>Pollen grains are one of the most characteristic elements
-found in powdered flowers, because they are so small that they
-are not broken up when the drug is milled.</p>
-
-<p>The two principal groups of pollen grains are, first, those with
-non-spiny walls (Plate 113); and, secondly, those with spiny
-walls (Plate 114), as shown in the two charts.</p>
-
-<p>In lavender flowers the pollen grains have six constrictions
-of the outer wall. This wall is slightly striated and the cell
-contents are granular.</p>
-
-<p>In clover flowers the pollen grains are mostly rounded in
-outline, the wall is uniformly thickened, and cell contents are
-coarsely granular.</p>
-
-<p>In belladonna flowers the pollen grains terminate in three
-blunt points.</p>
-
-<p>In Spanish saffron the pollen grains are spherical and the
-cell contents are granular.</p>
-
-<p><span class="pagenum" id="Page_271">[271]</span></p>
-
-<div class="figcenter illowp54" id="plate113" style="max-width: 45.5625em;">
-  <img class="w100 p1" src="images/plate113.jpg" alt="" />
-  <div class="caption">PLATE 113<br />
-<span class="smcap">Smooth-walled Pollen Grains</span>
-
-<div class="blockquotc">
-<p>1. Cloves (<i lang="la" xml:lang="la">Eugenia caryophyllata</i>, Thunb.). 2. Santonica (<i lang="la" xml:lang="la">Artemisia
-pauciflora</i>, Weber). 3. Elder (<i lang="la" xml:lang="la">Sambucus canadensis</i>, L.). 4. Century minor
-(<i lang="la" xml:lang="la">Erythræa centaurium</i> [L.], Pers.). 5. Pichi (<i lang="la" xml:lang="la">Fabiana imbricata</i>, R. and P.).
-6. Cyani. 7. Lavender (<i lang="la" xml:lang="la">Lavandula officinalis</i>, Chaix.). 8. Clover (<i lang="la" xml:lang="la">Trifolium
-pratense</i>, L.). 9. Belladonna (<i lang="la" xml:lang="la">Atropa belladonna</i>, L.). 10. Spanish saffron
-(<i lang="la" xml:lang="la">Crocus sativus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_272">[272]</span></p>
-
-<div class="figcenter illowp54" id="plate114" style="max-width: 45.4375em;">
-  <img class="w100 p1" src="images/plate114.jpg" alt="" />
-  <div class="caption">PLATE 114<br />
-<span class="smcap">Spiny Walled Pollen Grains</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Anthemis (<i lang="la" xml:lang="la">Anthemis nobilis</i>, L.).<br />
-2. Arnica (<i lang="la" xml:lang="la">Arnica montana</i>, L.).<br />
-3. Calendula (<i lang="la" xml:lang="la">Calendula officinalis</i>, L.).<br />
-4. Cassia flowers.<br />
-5. American saffron (<i lang="la" xml:lang="la">Carthamus tinctorius</i>, L.).<br />
-6. Blue malva flowers (<i lang="la" xml:lang="la">Malva sylvestris</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_273">[273]</span></p>
-
-<p>The non-spiny-walled pollen grains differ not only in microscopic
-appearance, but also in size. Clove pollen grains are
-the smallest, while Spanish saffron pollen grains are the largest.</p>
-
-<h5 id="NON-SPINY-WALLED_POLLEN_GRAINS">NON-SPINY-WALLED POLLEN GRAINS</h5>
-
-<p>In cloves the pollen grains show a six-sided, angled cavity
-and an outer wall which terminates in three slightly pointed,
-narrowly notched portions, separated by nearly straight walls.</p>
-
-<p>In santonica the pollen grains have smooth, unequally
-thickened walls, which are strongly constricted at three points,
-the outline resembling three half-circles placed together.</p>
-
-<p>In elder flowers the pollen grains appear circular or three-parted.
-The wall is of nearly uniform thickness, even at the
-constricted part of the grain.</p>
-
-<p>In century minor the pollen grains show three pronounced
-restrictions. The wall at these points is very thin. In pichi
-flowers the pollen grains are either circular or three-sided and
-three-pointed. Inside of each point there is a nearly white pore.
-In some of the grains the pollen tube has grown out of one of
-the pores.</p>
-
-<p>In cyani flowers the pollen grains are longer than broad and
-the cell contents appear to be divided into two end portions
-and an elevated middle portion.</p>
-
-<h5 id="SPINY-WALLED_POLLEN_GRAINS">SPINY-WALLED POLLEN GRAINS</h5>
-
-<p>In anthemis the pollen grains have unequally thickened
-walls constricted in three places. The spines are short, broad
-at the base, and sharp-pointed.</p>
-
-<p>In arnica flowers the pollen grains show three light-colored
-pores and numerous short spines.</p>
-
-<p>In calendula flowers the pollen grains show one or more
-pores, typically three pores. These pores appear as white spots,
-and the wall immediately over the pore is smooth and thinner
-than the remaining part of the wall; the spines are very numerous.</p>
-
-<p>In cassia flower pollen grains the outer wall is extended into
-a number of rounded projections which are frequently arranged
-in sets of fours.</p>
-
-<p>In American saffron flowers the pollen grains show one, two,
-or three light-colored pores; the spines are short and broad.</p>
-
-<p><span class="pagenum" id="Page_274">[274]</span></p>
-
-<p>In blue malva flowers the pollen grains are spherical and the
-outer wall extends into numerous spinelike projections.</p>
-
-<p>It will be observed that the spiny-walled pollen grains differ
-greatly in size, the smallest being the pollen grain of anthemis
-and the largest being the pollen grain of blue malva
-flowers.</p>
-
-<p>In matricaria are numerous, greenish-brown, spiny-walled
-pollen grains. In anthemis are multicellular, uniseriate non-glandular
-hairs with three or four short, broad, yellow-walled
-basal cells and a greatly elongated, thin, gray-walled
-apical cell.</p>
-
-<p>In arnica are multiseriated branched hairs of the pappus,
-and numerous large, yellowish, spiny-walled pollen grains.</p>
-
-<h5 id="STIGMA_PAPILL">STIGMA PAPILLÆ</h5>
-
-<p>The <span class="bold">papillæ of the stigma</span> of most flowers form a characteristic
-element even when the flower is powdered. In the case
-of composite flowers the papillæ of the disk and ray flowers
-differ. In American saffron the papillæ of the style differ in a
-recognizable way from the papillæ of the stigma.</p>
-
-<p>The papillæ of the stigma of the ray and disk flowers of
-arnica, anthemis, matricaria, and insect flowers differ greatly.
-Even the papillæ of the stigma of the ray and disk flowers differ.
-In all cases observed the papillæ of the ray flowers are smaller
-than the papillæ of the disk flowers.</p>
-
-<p>The papillæ of the stigma of saffron (Plate 115, Fig. 3) are
-long and tubular. These papillæ are nearly uniform in diameter,
-and the apex is blunt and rounded. The wall is slightly
-granular in appearance. The papillæ of the stigma of American
-saffron (Plate 116, Fig. 2) are short and tubular. Each papilla
-is broadest at the base and tapers to a slender point. The
-papillæ of that part of the style which emerges from the corolla
-(Plate 116, Fig. 1) are large and curved, and the walls are very
-thick. The apex of the papilla is frequently solid.</p>
-
-<p>The papillæ of the stigma of the ray flowers of anthemis
-(Plate 117, Fig. 1) have thin, slightly striated walls; while the
-papillæ of the stigma of the disk flowers (Plate 117, Fig. 2) are
-longer, the walls are thicker, and the cell content is denser.</p>
-
-<p><span class="pagenum" id="Page_275">[275]</span></p>
-
-<div class="figcenter illowp53" id="plate115" style="max-width: 44.625em;">
-  <img class="w100 p1" src="images/plate115.jpg" alt="" />
-  <div class="caption">PLATE 115<br />
-<span class="smcap">Papillæ</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Arnica ray flowers (<i lang="la" xml:lang="la">Arnica montana</i>, L.).<br />
-2. Insect flower disk (<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i> [Trev.], Vis.).<br />
-3. True saffron (<i lang="la" xml:lang="la">Crocus sativus</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_276">[276]</span></p>
-
-<div class="figcenter illowp53" id="plate116" style="max-width: 44.5em;">
-  <img class="w100 p1" src="images/plate116.jpg" alt="" />
-  <div class="caption">PLATE 116<br />
-<span class="smcap">Papillæ of Stigmas</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Stigma papillæ of American saffron (<i lang="la" xml:lang="la">Carthamus tinctorius</i>, L.) from that part of the style that emerges from the corolla.<br />
-2. Papillæ from the upper part of the stigma of American saffron.<br />
-3. Papillæ of the stigma of the disk flowers of arnica (<i lang="la" xml:lang="la">Arnica montana</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_277">[277]</span></p>
-
-<div class="figcenter illowp54" id="plate117" style="max-width: 45.5em;">
-  <img class="w100 p1" src="images/plate117.jpg" alt="" />
-  <div class="caption">PLATE 117<br />
-<span class="smcap">Papillæ of Stigmas</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Stigma papillæ of the ligulate flowers of anthemis (<i lang="la" xml:lang="la">Anthemis nobilis</i>, L.).<br />
-2. Stigma papillæ of the tubular flowers of anthemis.<br />
-3. Stigma papillæ of the ligulate flowers of matricaria (<i lang="la" xml:lang="la">Matricaria chamomilla</i>, L.).<br />
-4. Stigma papillæ of the disk flowers of matricaria.<br />
-5. Stigma papillæ of the ligulate flowers of insect flower (<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i> [Trev.], Vis.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_278">[278]</span></p>
-
-<p>The papillæ of the stigma of the ray (Plate 117, Fig. 3) and
-disk flowers (Plate 117, Fig. 5) of matricaria are similar in
-structure, but the papillæ of the disk flowers are larger.</p>
-
-<p>The papillæ of the stigma of the ligulate flowers of insect
-flowers (Plate 117, Fig. 5) are tubular; the walls are striated,
-and in each papilla there is a small yellow globule, while the
-papillæ of the disk flowers (Plate 115, Fig. 2) are long and
-tubular, and the walls are thick.</p>
-
-<p>The papillæ of the stigma of the ray flowers of arnica (Plate
-115, Fig. 1) are very short and tubular. The walls are thin
-and the cell contents appear as small, bright-yellow globules,
-while the papillæ of the stigma of the disk flowers (Plate 116,
-Fig. 3) are broadest at the base, the apex is pointed, and the
-yellow globules are larger.</p>
-
-<p>The <span class="bold">solitary</span> hairs are divided into the branched and non-branched
-hairs.</p>
-
-<h5 id="POWDERED_INSECT_FLOWERS">POWDERED INSECT FLOWERS</h5>
-
-<p>The microscopic examination of insect powder is difficult for
-the reason that there are so many elements to be constantly
-kept in mind. The parts of the flower which contribute characteristic
-cells are the stem, involucre, ray flowers, disk flowers,
-and the receptacle. In each of these parts there are many
-different types of cells.</p>
-
-<p>There are practically two types of flowers found in insect
-powder of commerce: first, closed or immature flowers, and
-secondly, open or mature flowers. As explained above, the
-half-open flowers consist largely of the two above-named varieties.
-Let us first consider the structure of the closed insect
-flowers as illustrated in Plate 118.</p>
-
-<p><span class="pagenum" id="Page_279">[279]</span></p>
-
-<div class="figcenter illowp54" id="plate118" style="max-width: 45.5em;">
-  <img class="w100 p1" src="images/plate118.jpg" alt="" />
-  <div class="caption">PLATE 118<br />
-<span class="smcap">Powdered Closed Insect Flower</span><br />
-(<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i>, [Trev.] Vis.)
-
-<div class="blockquotc">
-<p>1. Edge of scale. 2. Fibre of scale. 3. Hairs. 4. Upper epidermis of
-ray flower. 5. Under epidermis of ray flower. 6. Cross-section of ray petal.
-7. Parenchyma of ray flowers with crystals. 8. Lobe of disk petal. 9. Filament
-tissue. 10. Calyx tissue, 11. Lobe of stamen. 12. Pollen. 13. Papillæ of
-stigma. 14. Secretion cavity with surrounding cells. 15. Parenchyma of
-the receptacle.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_280">[280]</span></p>
-
-<p>The involucre has many characteristic cells. The more
-prominent ones seen in the powder are the edge of the scale with
-the attached hair (Fig. 1). These hairs (Fig. 3) are T-shaped.
-The terminal cell is expanded laterally, and it terminates in
-two points. Connecting the terminal cell with the epidermis
-are two or three cells which are slightly longer than broad.
-In the powder the terminal cell is usually attached to fragments
-only of the supporting cells. Fibres of the bracts have thick,
-wavy, porous walls, and they have a tendency to occur in masses.
-The upper epidermis (Fig. 4) of the ray-flower petal is prominently
-papillate. The under epidermis consists of wavy cells
-without papillæ. Another view of the papillæ is shown in
-Fig. 6. The parenchyma of the ray flowers (Fig. 7) contain
-cubical crystals. The lobe of the disk-flower petal (Fig. 8)
-is papillate at the end, the terminal cells have thick outer and
-thin inner walls. The filament tissue (Fig. 9) is composed of
-nearly square cells. The calyx tissue (Fig. 10) is made up of
-thin-walled cells with slightly papillate margins. The lobe of the
-stamen (Fig. 11) consists of nearly uniform epidermal cells
-which are in contact throughout their long diameter, while the
-hypodermal cells are thin-walled and angled. The pollen grains
-(Fig. 12) are dark yellowish green, thin, and the wall does not
-appear perforated by pores. The papillæ of the stigma (Fig. 13)
-are clustered, club-shaped, and nearly white in color. They
-are usually found detached in the powder. All parts of the
-pistil contain secreting cells, but the most conspicuous secreting
-cavities (Fig. 14) are those of the ovary. These cavities appear
-brownish in color and are surrounded by small cells which appear
-indistinct on account of the great number of superimposed cells.
-The parenchyma of the receptacle occurs in fragments which
-have strongly marked porous walls.</p>
-
-<h5 id="OPEN_INSECT_FLOWERS">OPEN INSECT FLOWERS</h5>
-
-<p>Many of the structures of open insect flowers (Plate 119)
-are similar to those found in the closed flower. There is practically
-no difference in the edge of the scale (Fig. 1); or the
-fibre of the scale (Fig. 2); or the T-shaped hairs (Fig. 3); or the
-upper epidermis of the ray flower (Fig. 4); or the under epidermis
-of the ray flower (Fig. 5); or the cross-section of the ray petal
-(Fig. 6); or the lobe of the disk petal (Fig. 7); or the filament
-tissue (Fig. 8); or the lobe of the stamen (Fig. 9); or the papillæ
-of the stigma (Fig. 12); or the parenchyma of the receptacle
-(Fig. 15). The difference in structure is found, first, in the
-involucre scales, which are more fibrous than the scales of the
-closed flowers; secondly, in the pollen (Fig. 11), which is less
-abundant than in the closed flower; it is also lighter in color
-and usually shows the wall perforated by three pores; thirdly,
-the outer layers of the achene consist of thick, porous-walled
-stone cells (Fig. 13), which occur singly or in groups; fourthly,
-the secretion cavity is broader and darker in color (Fig. 14).
-These differences enable one at once to distinguish between
-the closed and open insect flowers. Now, since the half-closed
-flowers consist almost wholly of a mixture of equal parts of
-closed and open flowers, it follows that the elements of these
-two flowers will be mixed in about equal proportions. Thus
-we are able to distinguish microscopically the three commercial
-varieties of insect powder&mdash;namely, closed insect flowers, open
-insect flowers, and half-open insect flowers.</p>
-
-<p><span class="pagenum" id="Page_281">[281]</span></p>
-
-<div class="figcenter illowp55" id="plate119" style="max-width: 46.125em;">
-  <img class="w100 p1" src="images/plate119.jpg" alt="" />
-  <div class="caption">PLATE 119<br />
-<span class="smcap">Powdered Open Insect Flower</span><br />
-(<i lang="la" xml:lang="la">Chrysanthemum cinerariifolium</i>, [Trev.] Vis.)
-
-<div class="blockquotc">
-<p>1. Edge of involucre scale. 2. Fibres of involucre scale. 3. Hairs.
-4. Upper epidermis of ray flower. 5. Under epidermis of ray flower.
-6. Cross-section of ray petal. 7. Lobe of disk flower. 8. Filament tissue.
-9. Lobe of stamen. 10. Calyx tissue, 11. Pollen. 12. Papillæ of the stigma.
-13. Stone cells from the achene and cross-section of achene. 14. Secretion
-cavity with surrounding cells. 15. Parenchyma of the receptacle.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_282">[282]</span></p>
-
-<p>Insect flowers are the most valuable vegetable insecticide
-known; yet much of its effectiveness is destroyed by the adulterants
-which are so readily identified by the compound microscope.</p>
-
-<h5 id="POWDERED_WHITE_DAISIES">POWDERED WHITE DAISIES</h5>
-
-<p>A common adulterant found in open insect flowers is the
-flower-heads of European daisy (<i lang="la" xml:lang="la">C. leucanthemum</i>). Examination
-of powdered flowers exported from Europe shows that the entire
-flower-head is ground and mixed with the insect flowers. In
-the cheaper varieties of open flowers, only the tubular flowers
-are added after they have been separated from the heads by
-crushing and sifting. These tubular flowers so closely resemble
-the tubular flowers of the true insect flowers that it is practically
-impossible to distinguish between them macroscopically. The
-quickest and surest way to identify them is to reduce a portion
-of the flowers to a fine powder and examine it microscopically.</p>
-
-<p>Certain structures of the white daisies (Plate 120) are somewhat
-similar to those found in insect flowers. These structures
-are the papillæ of the ray petal (Figs. 3, 5, and 13), the lobe of
-the disk petal (Fig. 14), and the lobe of the stamen and the
-pollen (Fig. 8).</p>
-
-<p>The differences are as follows: The under epidermis of the
-ray flowers is composed of wavy cells which are more elongated
-than the ray flowers of the under epidermis of the ray petal of
-insect flower. The filament tissue is made up of slightly beaded
-cells instead of smooth-walled cells. The papillæ of the stigma
-are smaller than the papillæ of insect flowers. The most striking
-difference is found in the structure of the achene. The epidermal
-tissue of the achene is composed of palisade cells (Fig. 10), which
-in the mature form have thick white walls and scarcely any
-cavity. These cells swell perceptibly when placed in water.
-The other striking feature of the achene is the bright red resin
-masses which occur free in the field. Even a small trace of
-daisies in insect powder can be identified.</p>
-
-<p><span class="pagenum" id="Page_283">[283]</span></p>
-
-<div class="figcenter illowp53" id="plate120" style="max-width: 44.75em;">
-  <img class="w100 p1" src="images/plate120.jpg" alt="" />
-  <div class="caption">PLATE 120<br />
-<span class="smcap">Powdered White Daisies</span> (<i lang="la" xml:lang="la">Chrysanthemum leucanthemum</i>, L.)
-
-<div class="blockquotc">
-<p>1 and 2. Scale tissue. 3, 5 and 13. Papillæ of petals. 4. Scale tissue.
-6. Lobe of ray petal. 7. Filament tissue. 8. Pollen. 9. Papillæ of stigma.
-10. Palisade cells of achene. 11. Resin masses. 12. Parenchyma of receptacle.
-14. Lobe of dish petal.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_284">[284]</span></p>
-
-<p>When studying flowers there should be considered the number
-and structure of pollen grains; the nature of the papillæ of the
-stigma and the petals; the nature of the hairs of the corolla and
-calyx, when present. In the composite flowers we should also
-consider the structure of the involucre scales, and, when present,
-the structure of the receptacle scales, as in the case of anthemus,
-and of the pappus hairs, as in the flowers of arnica, boneset,
-grindelia, and aromatic goldenrod.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_285">[285]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_VIII">CHAPTER VIII<br />
-<span class="fs80">FRUITS</span></h3>
-</div>
-
-<p>There is great variation in the structure of fruits, such a
-variation, in fact, that no one fruit has a structure typical of
-all the other fruits. Each fruit, however, has a pericarp and
-one or more seeds. The amount and structure of the cells
-forming the pericarp and the seeds of fruits differ in different
-fruits, but for each fruit there is a normal amount of, and a
-characteristic, cellular structure. Nearly all the important
-medicinal fruits are cremocarps or umbelliferous fruits.</p>
-
-<p>The plan of structure of cremocarps is similar, but they all
-have a different cellular structure. The epidermis may be
-simple or modified as papillæ or hairs. The secretion cavities
-may be absent (conium), or, when present, variable in number&mdash;cultivated
-celery seed has six, wild celery seed up to twelve,
-and anise up to twenty. The vascular bundles may be large or
-small. The endocarp cells may be two or more layers in thickness.
-The spermoderm may be thin or thick.</p>
-
-<p>The endosperm cells may vary in size and the cell contents
-may vary.</p>
-
-<h5 id="CELERY_FRUIT">CELERY FRUIT</h5>
-
-<p>The fruit of celery (Plate 121), like other umbelliferous
-fruits, is composed of the pericarp and the seed.</p>
-
-<p>The pericarp is composed of epicarp cells, mesocarp cells,
-endocarp cells, and in each rib a vascular bundle. The seed is
-composed of the spermoderm, endosperm, and embryo. Each
-of these parts has a characteristic structure.</p>
-
-<p><span class="bold">Epicarp</span>. The cells of the epicarp (Fig. 1) are papillæ and the
-outer wall is striated. The papillæ do not show, however, unless
-the cell is cut across the centre, which is the point at which the
-papillæ are located.</p>
-
-<p><span class="pagenum" id="Page_286">[286]</span></p>
-
-<div class="figcenter illowp50" id="plate121" style="max-width: 42.4375em;">
-  <img class="w100 p1" src="images/plate121.jpg" alt="" />
-  <div class="caption">PLATE 121<br />
-<span class="smcap">Cross-Section of Celery Fruit</span> (<i lang="la" xml:lang="la">Apium graveolens</i>, L.)
-
-<div class="blockquotc">
-<p>1. Epicarp. 2. Mesocarp. 3. Vascular bundle. 4. Endocarp.
-5. Spermoderm. 6. Endosperm. 7. Secretion cavity.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_287">[287]</span></p>
-
-<div class="figcenter illowp41" id="plate122" style="max-width: 34.9375em;">
-  <img class="w100 p1" src="images/plate122.jpg" alt="" />
-  <div class="caption">PLATE 122<br />
-<span class="smcap">Diagrammatic Drawing of the</span>
-
-<div class="blockquotc">
-<p class="noindent">1. Cross-section of wild celery seed (<i lang="la" xml:lang="la">Apium graveolens</i>, L.).<br />
-2. Cross-section of cultivated celery seed (<i lang="la" xml:lang="la">Apium graveolens</i>, L.).</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_288">[288]</span></p>
-
-<p><span class="bold">Mesocarp</span>. In the rib part of the mesocarp (Fig. 2) is a
-vascular bundle, and between the ribs one or more secretion
-cavities. The vascular bundles are small and are surrounded by
-irregular-shaped mesocarp cells.</p>
-
-<p>The <span class="bold">secretion cavities</span> (Fig. 7) are oval in form and the tissue
-bordering the cavity is reddish brown in color. The mesocarp
-cells around the secretion cavities are more elongated than the
-other mesocarp cells.</p>
-
-<p><span class="bold">Endocarp</span>. The endocarp cells are three layers in thickness.
-These cells are elongated transversely (Fig. 4).</p>
-
-<p><span class="bold">Spermoderm</span>. The cells of the spermoderm are indistinct,
-compressed, and dark brown in color (Fig. 5).</p>
-
-<p><span class="bold">Endosperm</span>. The endosperm cells (Fig. 6) make up the greater
-part of the fruit. The walls which are common to two cells
-are thick, non-beaded, and non-pitted, and the cavities of the
-cells are filled with aleurone grains.</p>
-
-<p><span class="bold">Embryo</span>. The embryo cells, which show only in certain
-sections, are similar to endosperm cells.</p>
-
-<p>In anise, hops, sumac, and cumin fruits are characteristic
-hairs.</p>
-
-<p>In star anise, sabal, allspice, cubeb, pepper, juniper, buckthorn,
-and phytolacca fruits are stone cells.</p>
-
-<p>In cubeb, pepper, and cardamon are characteristic masses of
-aggregate starch.</p>
-
-<p>In sabal, allspice, and juniper are characteristic secretion cells.</p>
-
-<p>In all the umbelliferous fruits, with the exception of conium,
-are yellow to brown secretion cavities.</p>
-
-<p>In cubeb and pepper is aggregate starch. Colocynth contains
-many single and double spiral vessels.</p>
-
-<p>Bitter orange contains solitary crystals and spongy parenchyma.</p>
-
-<p>When studying fruits we must consider the nature of the
-epicarp cells&mdash;whether simple or modified as papillæ or hairs;
-the form and structure of the mesocarp cells; the number, size,
-and structure of the vascular bundle; the size and number of
-the secretion cells or cavities; the number of layers and the
-structure of the endocarp cells; the number of layers of stone
-cells&mdash;when present; the color and width of the spermoderm
-layer; the structure and cell contents of the endosperm cells;
-the nature of the embryo cells, and the nature of the cell contents.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_289">[289]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_IX">CHAPTER IX<br />
-<span class="fs80">SEEDS</span></h3>
-</div>
-
-<p>Seeds are very variable in structure, so much so, in fact,
-that scarcely any two seeds have a similar structure. It is
-necessary, therefore, when examining seeds, to compare the structure
-of the seed under examination with authentic plates or
-with the section of a genuine seed. The layers of the seed
-are the spermoderm, perisperm, endosperm, and embryo. In
-some seeds the spermoderm forms the greater part of the seed;
-in others the perisperm is greatest in amount; in still others
-the cotyledons make up most of the seed, as in the mustards.
-The cells forming these different layers differ in form, structure,
-and number; therefore it is not difficult to distinguish and to
-differentiate between the different seeds when viewed as a section
-or as a powder. Almond is studied because it has most of
-the layers and cells found in seeds.</p>
-
-<h4 id="SPERMODERM">SPERMODERM</h4>
-
-<p>The <span class="bold">spermoderm</span> is the thin, brown, granular-appearing
-skin of the almond. The layers of the spermoderm are the
-epidermis, the hypoderm, the middle layers, and the inner
-epidermis.</p>
-
-<p>The <span class="bold">epidermis</span> consists of radially elongated, thick-walled
-stone cells which occur alone or in groups of two or more, but
-seldom as a continuous layer. The upper or outer part of the
-stone cells is non-porous, but the inner walls are strongly porous
-(Plate 123, Fig. 1).</p>
-
-<p>The <span class="bold">hypoderm</span>. The cells forming the hypoderm are compressed,
-the wall structure is practically indistinguishable, and
-the whole mass is reddish brown (Plate 123, Fig. 2).</p>
-
-<p>Occurring in this brown layer are several vascular bundles
-(Plate 123, Fig. 3).</p>
-
-<p><span class="pagenum" id="Page_290">[290]</span></p>
-
-<div class="figcenter illowp54" id="plate123" style="max-width: 45.0625em;">
-  <img class="w100 p1" src="images/plate123.jpg" alt="" />
-  <div class="caption">PLATE 123<br />
-<span class="smcap">Cross-Section Sweet Almond Seed</span>
-
-<div class="blockquotc">
-<p>1. Epidermis. 2. Hypoderm. 3. Vascular bundle. 4. Middle layer.
-5. Inner epidermis. 6. Endosperm. 7. Outer layer of the embryo. 8. Inner
-layers of the embryo.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_291">[291]</span></p>
-
-<p>The <span class="bold">middle layers</span>. The cells forming the middle layers
-(Fig. 4) have thin, wavy, light-colored walls which are frequently
-compressed, and it is with much difficulty that their outlines
-are made out.</p>
-
-<p>The <span class="bold">inner epidermis</span>. The cells forming the inner epidermis
-are rectangular in form, and they contain reddish-brown cell
-contents (Plate 123, Fig. 5).</p>
-
-<h4>ENDOSPERM</h4>
-
-<p>The <span class="bold">endosperm</span>. The cells forming the endosperm are large,
-rectangular in outline, usually one layer thick, and they contain
-aleurone grains.</p>
-
-<h4>EMBRYO</h4>
-
-<p>The <span class="bold">embryo</span>. The cells forming the outer layer of the embryo
-are smaller than the inner layers, and they are immediately
-inward from the layer of endosperm cells (Plate 123, Fig. 7).</p>
-
-<p>The cells forming the greater part of the embryo are large,
-rounded, and they contain aleurone grains and fixed oil (Plate
-123, Fig. 8).</p>
-
-<p>In white and black mustard are characteristic mucilage and
-palisade cells.</p>
-
-<p>In mix vomica, stropanthus, and St. Ignatius’s bean are
-characteristic hairs.</p>
-
-<p>In physostigma and kola are characteristic starch grains.</p>
-
-<p>In henbane, capsicum, stramonium, lobelia, and belladonna
-seeds are characteristic epidermal cells.</p>
-
-<p>In areca nut, colchicum, saw palmetto, and nux vomica are
-characteristic thick-walled, reserve cellulose cells.</p>
-
-<p>In cardamon seed are aggregate starch masses with irregular
-outlines.</p>
-
-<p>In bitter and sweet almond, linseed, pepo, and stropanthus
-are aleurone grains.</p>
-
-<p>In bitter and sweet almonds are stone cells.</p>
-
-<p>In linseed, quince seed, and in white and black mustard are
-epidermal cells with mucilaginous walls and contents, etc.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_292">[292]</span></p>
-
-<h3 class="nobreak" id="PIII_CHAPTER_X">CHAPTER X<br />
-<span class="fs80">ARRANGEMENT OF VASCULAR BUNDLES</span></h3>
-</div>
-
-<p>Having familiarized ourselves with the different types of
-mechanical and conducting cells, we shall now consider the
-different ways in which these cells are associated to form the
-<span class="bold">vascular</span> and <span class="bold">fibro-vascular bundles</span>.</p>
-
-<p>The simplest form of the vascular bundle occurs in petals,
-floral bracts, and leaves. In these parts the vascular bundle
-is made up of conducting cells only.</p>
-
-<p>In the great majority of cases, however, the conducting cells
-are associated with mechanical cells to form the fibro-vascular
-bundle.</p>
-
-<p>The fibro-vascular bundle is made up of, first, the <span class="bold">phloem</span>,
-which consists of sieve tubes, companion cells, bast fibres, and
-parenchyma; secondly, of the <span class="bold">xylem</span>, composed of vessels and
-tracheids, wood fibres and wood parenchyma; thirdly, of medullary
-rays (restricted to certain types); and fourthly, of the
-bundle sheath (restricted to certain types).</p>
-
-<h4 id="TYPES_OF_FIBRO-VASCULAR_BUNDLES">TYPES OF FIBRO-VASCULAR BUNDLES</h4>
-
-<p>There are three well-defined types of the fibro-vascular
-bundle, namely, the <span class="bold">radial</span>, the <span class="bold">concentric</span>, and the <span class="bold">collateral</span>
-types.</p>
-
-<h5 id="RADIAL_VASCULAR_BUNDLES">RADIAL VASCULAR BUNDLES</h5>
-
-<p>The radial type of bundle is met with most frequently in
-monocotyledonous roots.</p>
-
-<p>In this form (Plate 114) the xylem forms radial bands of
-tissue which alternate with isolated groups of phloem. The
-space between the phloem and xylem is filled in with either
-parenchyma or fibres, or both. In some cases the vessels of
-the xylem meet in the centre of the root, while in other cases
-the centre of the stem is occupied by pith parenchyma. Each
-bundle is surrounded by parenchyma cells, and in iris, calamus,
-and veratrum, rhizomes, and endodermis, surrounds the bundles
-located in the centre of the stem, consisting of thin-walled
-(mechanical) cells.</p>
-
-<p><span class="pagenum" id="Page_293">[293]</span></p>
-
-<div class="figcenter illowp62" id="plate124" style="max-width: 52.3125em;">
-  <img class="w100 p1" src="images/plate124.jpg" alt="" />
-  <div class="caption">PLATE 124<br />
-<span class="smcap">Cross-Section of a Radial Vascular Bundle of Skunk Cabbage Root</span><br />
-(<i lang="la" xml:lang="la">Symplocarpus fœtidus</i> [L.], Nutt.)
-
-<div class="blockquotc">
-<p class="noindent">1. Vessels.<br />
-2. Bundle sheath.<br />
-3. Parenchyma.<br />
-4. Sieve cells.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_294">[294]</span></p>
-
-<div class="figcenter illowp74" id="plate125" style="max-width: 62.125em;">
-  <img class="w100 p1" src="images/plate125.jpg" alt="" />
-  <div class="caption">PLATE 125<br />
-<span class="smcap">Cross-Section of a Phloem-Centric Bundle of Calamus
-Rhizome</span> (<i lang="la" xml:lang="la">Acorus calamus</i>, L.)
-
-<div class="blockquotc">
-<p class="noindent">1. Vessels.<br />
-2. Sieve cells.<br />
-3. Phloem parenchyma.<br />
-4. Parenchyma surrounding the bundles.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_295">[295]</span></p>
-
-<p>In sarsaparilla root, the pith is composed of thick-walled,
-porous pith parenchyma cells with starch. Outside the pith
-are arranged radial bands of oval vessels which decrease in size
-toward the periphery. Between the ends of these bands occur
-isolated groups of sieve cells.</p>
-
-<p>Surrounding the sieve cells and vessels are thick-walled,
-angled fibres.</p>
-
-<p>External to these cells is an endodermis composed of lignified
-brownish-colored cells one layer in thickness.</p>
-
-<h5 id="CONCENTRIC_VASCULAR_BUNDLES">CONCENTRIC VASCULAR BUNDLES</h5>
-
-<p>There are two principal types of the concentric bundle,
-namely, xylem-centric, in which the xylem is centric and the
-phloem is peripheral, as in veratrum root; and phloem-centric
-(Plate 125), in which the phloem is centric and the xylem peripheral,
-as in calamus rhizome.</p>
-
-<h5 id="COLLATERAL_VASCULAR_BUNDLES">COLLATERAL VASCULAR BUNDLES</h5>
-
-<p>There are three types of collateral vascular bundles&mdash;namely,
-closed collateral, bi-collateral, and open collateral.</p>
-
-<p>In the closed collateral bundle the phloem and xylem are
-not separated by a cambium layer, and in many cases the
-bundle is surrounded by thick, angled walled fibres, as in palm
-stem. The term closed bundle refers to the fact that there is
-no cambium between the xylem and phloem, therefore the
-bundle is “closed” to further growth, and not to the fact that
-it is frequently surrounded by fibres which prevent further
-growth. In podophyllum stem (Plate 126) the xylem portion
-of the bundle faces the centre of the stem and the phloem portion
-of the bundle faces the epidermis. The xylem and phloem are
-separated by a cambium layer, and both are surrounded by
-thick-walled angled fibres which are the chief mechanical cells
-of the stem. This bundle is, in fact, mechanically closed, but
-not physiologically because a cambium is present.</p>
-
-<p><span class="pagenum" id="Page_296">[296]</span></p>
-
-<div class="figcenter illowp80" id="plate126" style="max-width: 62.5em;">
-  <img class="w100 p1" src="images/plate126.jpg" alt="" />
-  <div class="caption">PLATE 126<br />
-<span class="smcap">Cross-Section of a Closed Collateral Bundle of Mandrake Stem</span><br />
-(<i lang="la" xml:lang="la">Podophyllum peltatum</i>, L.)
-
-<div class="blockquotc">
-<p class="noindent">1. Vessels.<br />
-2. Sieve cells.<br />
-3. Cambium.<br />
-4. Fibres.<br />
-5. Parenchyma.<br />
-6. Intercellular space.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_297">[297]</span></p>
-
-<div class="figcenter illowp61" id="plate127" style="max-width: 51.4375em;">
-  <img class="w100 p1" src="images/plate127.jpg" alt="" />
-  <div class="caption">PLATE 127<br />
-<span class="smcap">Bi-collateral bundle of Pumpkin Stem</span> (<i lang="la" xml:lang="la">Curcurbita pepo</i>, L.)
-
-<div class="blockquotc">
-<p class="noindent">1. Vessels.<br />
-2. Sieve tubes.</p>
-    </div>
-  </div>
-</div>
-
-<p><span class="pagenum" id="Page_298">[298]</span></p>
-
-<h5 id="BI-COLLATERAL_VASCULAR_BUNDLES">BI-COLLATERAL VASCULAR BUNDLES</h5>
-
-<p>In the bi-collateral vascular bundle (Plate 127) the xylem is
-in between two groups of phloem&mdash;namely, an inner group and
-an outer group.</p>
-
-<p>In pumpkin stem a bundle occurs in each angle of the stem.
-The entire bundle is surrounded by parenchyma cells.</p>
-
-<p>In an individual bundle the xylem consists of large circular
-vessels and a phloem containing large sieve cells, many of
-which show the yellow porous sieve plates.</p>
-
-<h5 id="OPEN_COLLATERAL_VASCULAR_BUNDLES">OPEN COLLATERAL VASCULAR BUNDLES</h5>
-
-<p>In the open collateral bundle (Plate 100) the xylem and
-phloem are separated by the cambium layer, which, through
-its divisions, causes the stem to increase in thickness each year.
-This type of bundle is characteristic of the stems and roots of
-dicotyledonous plants.</p>
-
-<p>The bi-collateral bundle occurs in many leaves. The xylem
-in such cases is central, the phloem strands occupying upper
-and lower peripheral positions.</p>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter">
-<p><span class="pagenum" id="Page_299">[299]</span></p>
-
-<h2 class="nobreak" id="INDEX">INDEX</h2>
-</div>
-
-
-<ul class="index">
-<li class="ifrst">Abbé condenser, illustration, <a href="#Page_11">11</a></li>
-
-<li class="indx">Absorption tissue, introduction, <a href="#Page_121">121</a></li>
-<li class="isub1">tissue of leaves, <a href="#Page_125">125</a></li>
-
-<li class="indx">Aerating tissue, introduction, <a href="#Page_151">151</a></li>
-
-<li class="indx">Annular vessels, illustration of, <a href="#Page_129">129</a></li>
-
-
-<li class="ifrst">Bark, of white pine powdered, description of, <a href="#Page_250">250</a></li>
-<li class="isub1">of white pine powdered, illustration of, <a href="#Page_251">251</a></li>
-<li class="isub1">unrossed white pine, cross-section, illustration of, <a href="#Page_249">249</a></li>
-
-<li class="indx">Barks, description of, <a href="#Page_248">248</a></li>
-<li class="isub1">diagnostic structures of, <a href="#Page_253">253</a></li>
-<li class="isub1">structural variations of, <a href="#Page_252">252</a></li>
-
-<li class="indx">Base sledge microtome, <a href="#Page_35">35</a></li>
-<li class="isub1">sledge microtome, illustration, <a href="#Page_35">35</a></li>
-
-<li class="indx">Bast fibres, <a href="#Page_89">89</a></li>
-<li class="isub1">branched, <a href="#Page_92">92</a></li>
-<li class="isub1">branched, illustrations, <a href="#Page_95">95</a></li>
-<li class="isub1">crystal bearing, <a href="#Page_90">90</a>, <a href="#Page_92">92</a></li>
-<li class="isub1">description of, <a href="#Page_100">100</a></li>
-<li class="isub1">groups of, illustrations, <a href="#Page_102">102</a></li>
-<li class="isub1">non-porous and non-striated, <a href="#Page_96">96</a></li>
-<li class="isub1">non-porous and non-striated, illustrations, <a href="#Page_101">101</a></li>
-<li class="isub1">non-porous and striated, <a href="#Page_96">96</a></li>
-<li class="isub1">occurrence in powdered drugs, <a href="#Page_103">103</a></li>
-<li class="isub1">of barks, illustrations, <a href="#Page_91">91</a>, <a href="#Page_93">93</a>, <a href="#Page_94">94</a></li>
-<li class="isub1">of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">porous and non-striated, illustrations, <a href="#Page_98">98</a></li>
-<li class="isub1">porous and striated, <a href="#Page_92">92</a></li>
-<li class="isub1">porous and striated, illustrations, <a href="#Page_97">97</a></li>
-<li class="isub1">storage function of, <a href="#Page_179">179</a></li>
-<li class="isub1">striated and non-porous, illustrations of, <a href="#Page_99">99</a></li>
-
-<li class="indx">Bi-collateral vascular bundles, description of, <a href="#Page_298">298</a></li>
-
-<li class="indx">Buchu stems, cross-section, illustration of, <a href="#Page_243">243</a></li>
-<li class="isub1">cross-section, illustration of, <a href="#Page_244">244</a></li>
-<li class="isub1">powdered, description of, <a href="#Page_245">245</a></li>
-<li class="isub1">powdered, illustration of, <a href="#Page_246">246</a></li>
-
-
-<li class="ifrst">Cambium of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_237">237</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Camera lucida, <a href="#Page_22">22</a></li>
-<li class="isub1">illustrations, <a href="#Page_22">22</a></li>
-
-<li class="indx">Care of microscope, <a href="#Page_28">28</a></li>
-
-<li class="indx">Celery fruit, diagrammatic drawing of, <a href="#Page_287">287</a></li>
-
-<li class="indx">Cell contents, <a href="#Page_182">182</a></li>
-<li class="isub1">aleurone grains, <a href="#Page_197">197</a></li>
-<li class="isub1">aleurone grains, description of, <a href="#Page_198">198</a></li>
-<li class="isub1">aleurone grains, form of, <a href="#Page_197">197</a></li>
-<li class="isub1">aleurone grains, structure of, <a href="#Page_197">197</a></li>
-<li class="isub1">aleurone grains, tests for, <a href="#Page_198">198</a></li>
-<li class="isub1">chlorophyll, <a href="#Page_182">182</a></li>
-<li class="isub1">crystals, <a href="#Page_200">200</a></li>
-<li class="isub1">crystals, composition of, <a href="#Page_200">200</a></li>
-<li class="isub1">crystals, micro-, <a href="#Page_200">200</a></li>
-<li class="isub1">crystals, raphides, <a href="#Page_200">200</a></li>
-<li class="isub1">crystals, rosette, <a href="#Page_200">200</a></li>
-<li class="isub1">crystals, solitary, variation of, <a href="#Page_205">205</a></li>
-<li class="isub1">cystoliths, <a href="#Page_210">210</a></li>
-<li class="isub1">cystoliths, forms of, <a href="#Page_210">210</a></li>
-<li class="isub1">cystoliths, occurrence of, <a href="#Page_215">215</a></li>
-<li class="isub1">cystoliths, tests for, <a href="#Page_215">215</a></li>
-<li class="isub1">hesperidin, <a href="#Page_196">196</a></li>
-<li class="isub1">hesperidin, test for, <a href="#Page_196">196</a></li>
-<li class="isub1">inulin, <a href="#Page_194">194</a></li>
-<li class="isub1">inulin, tests for, <a href="#Page_194">194</a></li>
-<li class="isub1">leucoplastids, <a href="#Page_183">183</a></li>
-<li class="isub1">mucilage, <a href="#Page_194">194</a></li>
-<li class="isub1"><span class="pagenum" id="Page_300">[300]</span>mucilage associated with raphides, tests for, <a href="#Page_194">194</a></li>
-<li class="isub1">mucilage, tests for, <a href="#Page_194">194</a></li>
-<li class="isub1">organic, <a href="#Page_182">182</a></li>
-<li class="isub1">starch grains, formation of, <a href="#Page_183">183</a></li>
-<li class="isub1">starch grains, hilum nature of, <a href="#Page_188">188</a></li>
-<li class="isub1">starch grains, hilum of, <a href="#Page_185">185</a></li>
-<li class="isub1">starch grains, mounting of, <a href="#Page_188">188</a></li>
-<li class="isub1">starch grains, occurrence of, <a href="#Page_184">184</a></li>
-<li class="isub1">starch grains, outline of, <a href="#Page_185">185</a></li>
-<li class="isub1">starch grains, size of, <a href="#Page_185">185</a></li>
-<li class="isub1">starch grains, tests for, <a href="#Page_188">188</a></li>
-<li class="isub1">tannin, <a href="#Page_196">196</a></li>
-<li class="isub1">tannin, occurrence of, <a href="#Page_196">196</a></li>
-<li class="isub1">tannin, test for, <a href="#Page_197">197</a></li>
-<li class="isub1">volatile oil, test for, <a href="#Page_196">196</a></li>
-<li class="isub1">volatile oils, <a href="#Page_196">196</a></li>
-
-<li class="indx">Cell division common to onion root, <a href="#Page_56">56</a></li>
-
-<li class="indx">Cell plate, <a href="#Page_55">55</a></li>
-
-<li class="indx">Cell sap, <a href="#Page_53">53</a></li>
-
-<li class="indx">Cell, typical, <a href="#Page_53">53</a></li>
-
-<li class="indx">Cell wall, <a href="#Page_53">53</a></li>
-
-<li class="indx">Chromatin, <a href="#Page_54">54</a></li>
-
-<li class="indx">Chromatin granules, <a href="#Page_55">55</a></li>
-
-<li class="indx">Chromatophores, <a href="#Page_53">53</a></li>
-
-<li class="indx">Chromosomes, <a href="#Page_55">55</a></li>
-
-<li class="indx">Closed collateral bundles of mandrake stem, cross-section illustration of, <a href="#Page_296">296</a></li>
-
-<li class="indx">Collateral vascular bundles, <a href="#Page_295">295</a></li>
-
-<li class="indx">Collenchyma cells, composition of walls, <a href="#Page_109">109</a></li>
-<li class="isub1">illustrations, <a href="#Page_108">108</a></li>
-<li class="isub1">occurring in catnip and motherwort, illustrations, <a href="#Page_107">107</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">structure of, <a href="#Page_106">106</a></li>
-
-<li class="indx">Compound microscope, illustration, <a href="#Page_10">10</a></li>
-<li class="isub1">microscope, mechanical parts of, <a href="#Page_7">7</a>, <a href="#Page_8">8</a></li>
-<li class="isub1">microscope of Robert Hooke, illustration, <a href="#Page_8">8</a></li>
-<li class="isub1">microscope, optical parts of, <a href="#Page_9">9</a>, <a href="#Page_11">11</a>, <a href="#Page_12">12</a></li>
-<li class="isub1">microscopes, introduction, <a href="#Page_7">7</a></li>
-
-<li class="indx">Concentric vascular bundles, <a href="#Page_295">295</a></li>
-
-<li class="indx">Conducting tissue, introduction, <a href="#Page_126">126</a></li>
-
-<li class="indx">Cork cells, origin of, <a href="#Page_88">88</a></li>
-
-<li class="indx">Cortical parenchyma, conduction by, <a href="#Page_147">147</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Cortex, of pink root, <a href="#Page_219">219</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_233">233</a></li>
-
-<li class="indx">Cover glasses, <a href="#Page_43">43</a></li>
-<li class="isub1">illustrations, <a href="#Page_44">44</a></li>
-
-<li class="indx">Crystal cavities, <a href="#Page_176">176</a></li>
-<li class="isub1">cells, storage function of, <a href="#Page_179">179</a></li>
-
-<li class="indx">Cutting sections, <a href="#Page_31">31</a></li>
-
-<li class="indx">Cystoliths, illustrations of, <a href="#Page_214">214</a></li>
-
-<li class="indx">Cytoplasm, <a href="#Page_53">53</a></li>
-
-
-<li class="ifrst">Daisies, white, powdered, description of, <a href="#Page_282">282</a></li>
-<li class="isub1">illustration of, <a href="#Page_283">283</a></li>
-
-<li class="indx">Dissecting microscope, illustration, <a href="#Page_5">5</a></li>
-<li class="isub1">needles, <a href="#Page_46">46</a></li>
-<li class="isub1">needles, illustration, <a href="#Page_46">46</a></li>
-
-<li class="indx">Drawing apparatus, illustration, <a href="#Page_23">23</a></li>
-
-
-<li class="ifrst">Ectoplast, <a href="#Page_53">53</a></li>
-
-<li class="indx">Embryo, diagnostic structures of, <a href="#Page_291">291</a></li>
-
-<li class="indx">Endocarp of celery fruit, <a href="#Page_288">288</a></li>
-
-<li class="indx">Endodermal cells, illustrations of longitudinal sections, <a href="#Page_119">119</a></li>
-<li class="isub1">illustrations of cross-sections, <a href="#Page_117">117</a></li>
-<li class="isub1">introduction, <a href="#Page_116">116</a></li>
-<li class="isub1">structure of, <a href="#Page_116">116</a>, <a href="#Page_118">118</a></li>
-
-<li class="indx">Endodermis, of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">of pink root, <a href="#Page_219">219</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-
-<li class="indx">Endosperm of celery fruit, <a href="#Page_288">288</a></li>
-<li class="isub1">of seeds, <a href="#Page_291">291</a></li>
-
-<li class="indx">Epicarp of celery fruit, <a href="#Page_285">285</a></li>
-
-<li class="indx">Epidermal cells of leaves, storage function of, <a href="#Page_179">179</a></li>
-
-<li class="indx">Epidermis, surface deposits of, <a href="#Page_62">62</a></li>
-<li class="isub1">of herbaceous stems, illustrations of, <a href="#Page_152">152</a></li>
-<li class="isub1">of klip buchu leaf, <a href="#Page_260">260</a></li>
-<li class="isub1">of leaves, illustrations of, <a href="#Page_155">155</a></li>
-<li class="isub1">of mountain laurel, <a href="#Page_264">264</a></li>
-<li class="isub1">of pink root, <a href="#Page_219">219</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of seeds, <a href="#Page_289">289</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_233">233</a></li>
-<li class="isub1">of testa, <a href="#Page_63">63</a></li>
-
-<li class="indx"><span class="pagenum" id="Page_301">[301]</span>Epidermis of trailing arbutus, <a href="#Page_264">264</a></li>
-
-<li class="indx">Equatorial plane, <a href="#Page_55">55</a></li>
-<li class="isub1">plate, <a href="#Page_55">55</a></li>
-
-
-<li class="ifrst">Fibro-vascular bundles, composition of, <a href="#Page_292">292</a></li>
-<li class="isub1">of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">types of, <a href="#Page_292">292</a></li>
-
-<li class="indx">Flowers, diagnostic structures of, <a href="#Page_284">284</a></li>
-<li class="isub1">parts of, <a href="#Page_270">270</a></li>
-
-<li class="indx">Folding magnifier, <a href="#Page_4">4</a></li>
-<li class="isub1">illustration, <a href="#Page_4">4</a></li>
-
-<li class="indx">Fruits, cellular structure of, <a href="#Page_285">285</a></li>
-<li class="isub1">diagnostic  characteristics of, <a href="#Page_288">288</a></li>
-<li class="isub1">diagnostic structures of, <a href="#Page_288">288</a></li>
-
-
-<li class="ifrst">Glandular hairs of peppermint, <a href="#Page_178">178</a></li>
-<li class="isub1">illustrations of, <a href="#Page_165">165</a></li>
-<li class="isub1">multicellular, <a href="#Page_164">164</a></li>
-<li class="isub1">multicellular, multiseriate stalked, <a href="#Page_166">166</a></li>
-<li class="isub1">multicellular, multiseriate stalked, description of, <a href="#Page_166">166</a></li>
-<li class="isub1">multicellular, multiseriate stalked, occurrence, <a href="#Page_166">166</a></li>
-<li class="isub1">multicellular sessile, <a href="#Page_164">164</a></li>
-<li class="isub1">multicellular stalked, <a href="#Page_164">164</a></li>
-<li class="isub1">multicellular, uniseriate stalked, <a href="#Page_164">164</a></li>
-<li class="isub1">stalked, illustrations of, <a href="#Page_167">167</a></li>
-<li class="isub1">storage function of, <a href="#Page_178">178</a></li>
-<li class="isub1">unicellular, <a href="#Page_164">164</a></li>
-<li class="isub1">unicellular, multiseriate stalked, <a href="#Page_164">164</a></li>
-<li class="isub1">unicellular sessile, <a href="#Page_164">164</a></li>
-<li class="isub1">unicellular stalked, <a href="#Page_164">164</a></li>
-<li class="isub1">unicellular, uniseriate stalked, <a href="#Page_164">164</a></li>
-
-<li class="indx">Glandular tissue, introduction, <a href="#Page_164">164</a></li>
-
-<li class="indx">Glass slides, <a href="#Page_44">44</a></li>
-<li class="isub1">illustrations, <a href="#Page_44">44</a></li>
-
-<li class="indx">Greenough binocular microscope, <a href="#Page_15">15</a></li>
-<li class="isub1">illustration, <a href="#Page_15">15</a></li>
-
-<li class="indx">Guard cells, <a href="#Page_151">151</a></li>
-
-
-<li class="ifrst">Hairs, multicellular, multicellular non-branched, illustration, <a href="#Page_75">75</a></li>
-<li class="isub1">multicellular, multiseriate branched, of Shepherdia, <a href="#Page_78">78</a></li>
-<li class="isub1">multicellular, multiseriate branched, <a href="#Page_77">77</a>, <a href="#Page_82">82</a></li>
-<li class="isub1">multicellular, multiseriate branched, illustrations, <a href="#Page_79">79</a>, <a href="#Page_81">81</a></li>
-<li class="isub1">multicellular, multiseriate non-branched, <a href="#Page_74">74</a></li>
-<li class="isub1">multicellular, uniseriate branched, illustration, <a href="#Page_76">76</a></li>
-<li class="isub1">multicellular, uniseriate non-branched, <a href="#Page_72">72</a></li>
-<li class="isub1">multicellular, uniseriate non-branched, illustrations of, <a href="#Page_73">73</a></li>
-
-<li class="indx">Hand cylinder microtome, illustration, <a href="#Page_34">34</a></li>
-<li class="isub1">microtome, <a href="#Page_31">31</a></li>
-<li class="isub1">microtome, illustration, <a href="#Page_31">31</a></li>
-<li class="isub1">table microtome, <a href="#Page_34">34</a></li>
-<li class="isub1">table microtome, illustration, <a href="#Page_34">34</a></li>
-
-<li class="indx">Horehound, powdered, description of, <a href="#Page_237">237</a></li>
-<li class="isub1">powdered, illustration of, <a href="#Page_238">238</a></li>
-<li class="isub1">spurious, powdered, description of, <a href="#Page_237">237</a></li>
-<li class="isub1">spurious, powdered, illustration of, <a href="#Page_239">239</a></li>
-
-<li class="indx">Hypoderm of seeds, <a href="#Page_289">289</a></li>
-
-<li class="indx">Hypodermal cells, of leaves, storage function of, <a href="#Page_179">179</a></li>
-<li class="isub1">illustrations, <a href="#Page_120">120</a></li>
-<li class="isub1">structure of, <a href="#Page_118">118</a></li>
-
-<li class="indx">Hypoderms, of klip buchu leaf, <a href="#Page_260">260</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_221">221</a></li>
-
-
-<li class="ifrst">Illumination for microscope, <a href="#Page_26">26</a></li>
-
-<li class="indx">Indirect cell division, <a href="#Page_54">54</a>, <a href="#Page_55">55</a></li>
-
-<li class="indx">Inner bark of white pine, <a href="#Page_248">248</a></li>
-<li class="isub1">epidermis of seeds, <a href="#Page_291">291</a></li>
-
-<li class="indx">Insect flower leaves, powdered, illustrations of, <a href="#Page_268">268</a></li>
-<li class="isub1">stems, description of, <a href="#Page_241">241</a></li>
-<li class="isub1">stems, powdered, illustration of, <a href="#Page_240">240</a></li>
-
-<li class="indx">Insect flowers, closed, powdered, illustration of, <a href="#Page_279">279</a></li>
-<li class="isub1">open, description of, <a href="#Page_280">280</a></li>
-<li class="isub1">open, powdered, illustration of, <a href="#Page_281">281</a></li>
-<li class="isub1">powdered, description of, <a href="#Page_278">278</a></li>
-
-<li class="indx">Intercellular spaces, <a href="#Page_158">158</a></li>
-<li class="isub1">illustrations of, <a href="#Page_160">160</a>, <a href="#Page_161">161</a></li>
-
-<li class="indx">Internal phloem, of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Inulin, illustrations of, <a href="#Page_195">195</a></li>
-
-
-<li class="ifrst">Karyokinesis, <a href="#Page_54">54</a>, <a href="#Page_55">55</a></li>
-
-<li class="indx">Klip buchu, cross-section, illustration of, <a href="#Page_261">261</a></li>
-<li class="isub1">powdered, description of, <a href="#Page_262">262</a></li>
-<li class="isub1">powdered, illustration of, <a href="#Page_263">263</a></li>
-
-
-<li class="ifrst"><span class="pagenum" id="Page_302">[302]</span>Labeling, <a href="#Page_47">47</a></li>
-
-<li class="indx">Latex cavities, <a href="#Page_176">176</a></li>
-<li class="isub1">tube cavities, <a href="#Page_176">176</a></li>
-<li class="isub1">tubes, <a href="#Page_142">142</a>, <a href="#Page_144">144</a></li>
-<li class="isub1">tubes, illustration of, <a href="#Page_145">145</a></li>
-<li class="isub1">vessels, illustrations of, <a href="#Page_146">146</a></li>
-
-<li class="indx">Leaf epidermis, <a href="#Page_59">59</a></li>
-<li class="isub1">illustrations, <a href="#Page_60">60</a>, <a href="#Page_61">61</a></li>
-
-<li class="indx">Leaf parenchyma, conduction by, <a href="#Page_150">150</a></li>
-
-<li class="indx">Leaves, diagnostic structures of, <a href="#Page_267">267</a></li>
-<li class="isub1">stomata, <a href="#Page_260">260</a></li>
-
-<li class="indx">Lenticel, illustration of cross-section, <a href="#Page_159">159</a></li>
-
-<li class="indx">Lenticels, ærating function of, <a href="#Page_157">157</a></li>
-<li class="isub1">structure of, <a href="#Page_158">158</a></li>
-
-<li class="indx">Linin, <a href="#Page_54">54</a></li>
-
-<li class="indx">Long paraffin process, <a href="#Page_29">29</a></li>
-
-
-<li class="ifrst">Machine microtomes, <a href="#Page_32">32</a></li>
-
-<li class="indx">Measuring cylinder, <a href="#Page_40">40</a></li>
-<li class="isub1">illustration, <a href="#Page_40">40</a></li>
-
-<li class="indx">Mechanical stage, <a href="#Page_21">21</a></li>
-<li class="isub1">stage, illustration, <a href="#Page_22">22</a></li>
-<li class="isub1">tissue, <a href="#Page_89">89</a></li>
-
-<li class="indx">Medullary ray, <a href="#Page_139">139</a></li>
-<li class="isub1">bundle, <a href="#Page_139">139</a></li>
-<li class="isub1">bundle in tangential-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">cell, <a href="#Page_141">141</a></li>
-<li class="isub1">cell, arrangement of, in the ray, <a href="#Page_142">142</a></li>
-<li class="isub1">cell, structure of, <a href="#Page_142">142</a></li>
-<li class="isub1">cells, in cross-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">cells, in radial-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">cells, in tangential-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">cells, of ruellia stem, <a href="#Page_237">237</a></li>
-
-<li class="indx">Medullary rays, illustration of cross-sections of, <a href="#Page_143">143</a></li>
-<li class="isub1">illustration of longitudinal section, <a href="#Page_140">140</a></li>
-<li class="isub1">in cross-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">in radial-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_227">227</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of white pine bark, <a href="#Page_250">250</a></li>
-
-<li class="indx">Mesocarp of celery fruit, <a href="#Page_285">285</a></li>
-
-<li class="indx">Method of mounting specimens, <a href="#Page_41">41</a></li>
-
-<li class="indx">Micro-crystals, illustrations of, <a href="#Page_201">201</a></li>
-<li class="isub1">lamp, <a href="#Page_27">27</a></li>
-
-<li class="indx">Micrometer eye-pieces, <a href="#Page_21">21</a></li>
-<li class="isub1">illustrations, <a href="#Page_20">20</a>, <a href="#Page_21">21</a></li>
-
-<li class="indx">Microphotographic apparatus, <a href="#Page_24">24</a></li>
-<li class="isub1">illustration, <a href="#Page_24">24</a></li>
-
-<li class="indx">Microscope, how to use, <a href="#Page_25">25</a></li>
-
-<li class="indx">Microscopic measurements, <a href="#Page_19">19</a></li>
-
-<li class="indx">Microtome, care of, <a href="#Page_36">36</a></li>
-
-<li class="indx">Middle bark of white pine, <a href="#Page_248">248</a></li>
-<li class="isub1">lamella, <a href="#Page_55">55</a></li>
-<li class="isub1">layers of seeds, <a href="#Page_291">291</a></li>
-
-<li class="indx">Minor rotary microtome, <a href="#Page_36">36</a></li>
-<li class="isub1">illustration, <a href="#Page_36">36</a></li>
-
-<li class="indx">Mountain laurel, cross-section, illustration of, <a href="#Page_265">265</a></li>
-
-<li class="indx">Mucilage cavities, <a href="#Page_172">172</a>, <a href="#Page_176">176</a></li>
-
-<li class="indx">Multicellular hair, <a href="#Page_72">72</a></li>
-
-
-<li class="ifrst">Nuclear membrane, <a href="#Page_55">55</a></li>
-<li class="isub1">spindle, <a href="#Page_55">55</a></li>
-
-<li class="indx">Nucleoli, <a href="#Page_55">55</a></li>
-
-<li class="indx">Nucleus, <a href="#Page_53">53</a></li>
-
-
-<li class="ifrst">Objectives, illustrations, <a href="#Page_11">11</a></li>
-
-<li class="indx">Ocular micrometer, <a href="#Page_19">19</a></li>
-<li class="isub1">illustration, <a href="#Page_19">19</a></li>
-
-<li class="indx">Oil cavities, occurrence, <a href="#Page_178">178</a></li>
-<li class="isub1">of leaves, <a href="#Page_178">178</a></li>
-<li class="isub1">of seeds, <a href="#Page_178">178</a></li>
-<li class="isub1">unicellular, <a href="#Page_172">172</a></li>
-
-<li class="indx">Open collateral vascular bundles, description of, <a href="#Page_298">298</a></li>
-
-<li class="indx">Origin of multicellular plants, <a href="#Page_57">57</a></li>
-
-<li class="indx">Outer bark of white pine, <a href="#Page_248">248</a></li>
-
-
-<li class="ifrst">Palisade parenchyma, conduction by, <a href="#Page_150">150</a></li>
-
-<li class="indx">Papillæ, <a href="#Page_67">67</a></li>
-<li class="isub1">illustrations of, <a href="#Page_275">275</a></li>
-<li class="isub1">of stigmas, illustrations of, <a href="#Page_276">276</a>, <a href="#Page_277">277</a></li>
-<li class="isub1">stigma, description of, <a href="#Page_274">274</a></li>
-
-<li class="indx">Paraffin, blocks, <a href="#Page_31">31</a></li>
-<li class="isub1">embedding oven, illustration, <a href="#Page_30">30</a></li>
-
-<li class="indx">Parenchyma, aquatic plant, <a href="#Page_150">150</a></li>
-<li class="isub1">cells of white pine, <a href="#Page_248">248</a></li>
-<li class="isub1">conduction by, <a href="#Page_144">144</a></li>
-<li class="isub1">cortical, illustrations of, <a href="#Page_148">148</a></li>
-<li class="isub1">of mountain laurel, <a href="#Page_264">264</a></li>
-<li class="isub1">of trailing arbutus, <a href="#Page_264">264</a></li>
-<li class="isub1">pith, illustrations of, <a href="#Page_149">149</a></li>
-
-<li class="indx">Pericycle of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-
-<li class="indx"><span class="pagenum" id="Page_303">[303]</span>Periderm, <a href="#Page_80">80</a></li>
-<li class="isub1">cork, <a href="#Page_80">80</a></li>
-<li class="isub1">illustrations of, <a href="#Page_86">86</a></li>
-<li class="isub1">of cascara sagrada, illustrations, <a href="#Page_84">84</a></li>
-<li class="isub1">of white oak bark, illustration of, <a href="#Page_87">87</a></li>
-<li class="isub1">parenchyma and stone cells, <a href="#Page_85">85</a></li>
-<li class="isub1">stone cells, <a href="#Page_85">85</a></li>
-
-<li class="indx">Permanent mounts, <a href="#Page_41">41</a></li>
-
-<li class="indx">Pharmacognostic microscope, illustration, <a href="#Page_12">12</a></li>
-
-<li class="indx">Phloem, centric bundle of calamus, cross-section, illustration of, <a href="#Page_294">294</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_233">233</a></li>
-
-<li class="indx">Phloem parenchyma, conduction by, <a href="#Page_150">150</a></li>
-<li class="isub1">of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_223">223</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Photosynthetic tissue, <a href="#Page_163">163</a></li>
-
-<li class="indx">Pink root, description of, <a href="#Page_227">227</a></li>
-
-<li class="indx">Pith parenchyma, conduction by, <a href="#Page_147">147</a></li>
-<li class="isub1">of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_227">227</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_237">237</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Pitted vessels, with bordered pores, illustration of, <a href="#Page_135">135</a></li>
-<li class="isub1">illustrations of, <a href="#Page_134">134</a></li>
-
-<li class="indx">Plant hairs, forms of, <a href="#Page_67">67</a></li>
-<li class="isub1">introduction, <a href="#Page_66">66</a></li>
-
-<li class="indx">Polar caps, <a href="#Page_55">55</a></li>
-
-<li class="indx">Polarization microscope, <a href="#Page_16">16</a></li>
-<li class="isub1">illustration, <a href="#Page_16">16</a></li>
-
-<li class="indx">Pollen grains, <a href="#Page_270">270</a></li>
-<li class="isub1">non-spiny-walled, description of, <a href="#Page_273">273</a></li>
-<li class="isub1">smooth-walled, illustrations of, <a href="#Page_271">271</a></li>
-<li class="isub1">spiny-walled, description of, <a href="#Page_273">273</a></li>
-<li class="isub1">spiny-walled, illustrations of, <a href="#Page_272">272</a></li>
-
-<li class="indx">Preparation of specimens for cutting, <a href="#Page_28">28</a></li>
-
-<li class="indx">Protoplast, <a href="#Page_53">53</a></li>
-
-
-<li class="ifrst">Quassia wood, cross-section, illustration of, <a href="#Page_255">255</a></li>
-<li class="isub1">radial-section, illustration of, <a href="#Page_257">257</a></li>
-
-
-<li class="ifrst">Radial vascular bundles, <a href="#Page_292">292</a></li>
-<li class="isub1">skunk cabbage root, cross-section, illustration of, <a href="#Page_293">293</a></li>
-
-<li class="indx">Raphides, illustrations of, <a href="#Page_203">203</a></li>
-
-<li class="indx">Reading glass, <a href="#Page_4">4</a></li>
-<li class="isub1">illustration, <a href="#Page_4">4</a></li>
-
-<li class="indx">Reagent set, illustration, <a href="#Page_39">39</a></li>
-
-<li class="indx">Reagents, list of, <a href="#Page_38">38</a></li>
-
-<li class="indx">Research microscope, <a href="#Page_13">13</a></li>
-<li class="isub1">illustration, <a href="#Page_14">14</a></li>
-
-<li class="indx">Reserve cellulose, illustrations of, <a href="#Page_180">180-181</a></li>
-
-<li class="indx">Reticulate vessels, illustrations of, <a href="#Page_133">133</a></li>
-
-<li class="indx">Root hairs, <a href="#Page_121">121</a>, <a href="#Page_122">122</a>, <a href="#Page_125">125</a></li>
-<li class="isub1">illustration of, <a href="#Page_123">123</a></li>
-<li class="isub1">illustration of fragments, <a href="#Page_124">124</a></li>
-
-<li class="indx">Roots and rhizomes, <a href="#Page_219">219</a></li>
-<li class="isub1">diagnostic structures of, <a href="#Page_227">227</a></li>
-
-<li class="indx">Rosette and solitary crystals, illustrations of, <a href="#Page_213">213</a></li>
-<li class="isub1">crystals, illustrations of, <a href="#Page_204">204</a></li>
-<li class="isub1">crystals, inclosed, illustrations of, <a href="#Page_206">206</a></li>
-
-<li class="indx">Ruellia ciliosa, Pursh., powdered, illustration of, <a href="#Page_229">229</a></li>
-<li class="isub1">ciliosa, Pursh., rhizome, cross-section, illustration of, <a href="#Page_225">225</a></li>
-<li class="isub1">ciliosa, Pursh., stem, cross-section, illustration of, <a href="#Page_236">236</a></li>
-<li class="isub1">root, description of, <a href="#Page_227">227</a></li>
-<li class="isub1">root, illustration of, <a href="#Page_222">222</a></li>
-
-
-<li class="ifrst">Scalpels, <a href="#Page_46">46</a></li>
-<li class="isub1">illustration, <a href="#Page_47">47</a></li>
-
-<li class="indx">Scissors, <a href="#Page_46">46</a></li>
-<li class="isub1">illustration, <a href="#Page_46">46</a></li>
-
-<li class="indx">Sclariform vessels, illustrations of, <a href="#Page_132">132</a></li>
-
-<li class="indx">Seeds, parts of, <a href="#Page_289">289</a></li>
-
-<li class="indx">Secretion cavities, of celery fruit, <a href="#Page_288">288</a></li>
-<li class="isub1">description of, <a href="#Page_176">176</a></li>
-<li class="isub1">illustrations of, <a href="#Page_169">169-171</a></li>
-<li class="isub1">introduction, <a href="#Page_166">166</a></li>
-<li class="isub1">lysigenous, <a href="#Page_168">168</a></li>
-<li class="isub1">schizogenous, <a href="#Page_168">168</a></li>
-<li class="isub1">schizo-lysigenous, <a href="#Page_168">168</a></li>
-<li class="isub1">unicellular, <a href="#Page_168">168</a></li>
-
-<li class="indx"><span class="pagenum" id="Page_304">[304]</span>Secretion cells, of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">of white pine, <a href="#Page_248">248</a></li>
-
-<li class="indx">Short paraffin process, <a href="#Page_29">29</a></li>
-
-<li class="indx">Sieve cells, of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_235">235</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Sieve plate, <a href="#Page_138">138</a></li>
-<li class="isub1">illustration of, <a href="#Page_137">137</a></li>
-
-<li class="indx">Sieve tube, illustration of, <a href="#Page_137">137</a></li>
-<li class="isub1">tubes, introduction, <a href="#Page_136">136</a></li>
-<li class="isub1">tubes, structure, <a href="#Page_136">136</a></li>
-
-<li class="indx">Simple microscope, introduction, <a href="#Page_3">3</a></li>
-
-<li class="indx">Slide box, <a href="#Page_48">48</a></li>
-<li class="isub1">box, illustration, <a href="#Page_48">48</a></li>
-<li class="isub1">cabinet, <a href="#Page_49">49</a></li>
-<li class="isub1">cabinet, illustration of, <a href="#Page_49">49</a></li>
-<li class="isub1">forceps, <a href="#Page_45">45</a></li>
-<li class="isub1">forceps, illustrations, <a href="#Page_45">45</a></li>
-<li class="isub1">tray, <a href="#Page_48">48</a></li>
-<li class="isub1">tray, illustration, <a href="#Page_48">48</a></li>
-
-<li class="indx">Solitary crystals, illustrations of, <a href="#Page_207">207-209</a>, <a href="#Page_211">211</a>, <a href="#Page_212">212</a></li>
-<li class="isub1">unicellular hairs, <a href="#Page_69">69</a></li>
-
-<li class="indx">Special research microscope, <a href="#Page_14">14</a></li>
-<li class="isub1">illustration, <a href="#Page_14">14</a></li>
-
-<li class="indx">Specimens, preservation of, <a href="#Page_48">48</a></li>
-
-<li class="indx">Spermoderm, of celery fruit, <a href="#Page_288">288</a></li>
-<li class="isub1">of seeds, <a href="#Page_289">289</a></li>
-
-<li class="indx">Spigelia marylandica, powdered, illustration of, <a href="#Page_228">228</a></li>
-<li class="isub1">rhizome, cross-section, illustration of, <a href="#Page_224">224</a></li>
-<li class="isub1">root, cross-section, illustration of, <a href="#Page_220">220</a></li>
-<li class="isub1">stem, cross-section, illustration of, <a href="#Page_234">234</a></li>
-
-<li class="indx">Spindle fibres, <a href="#Page_55">55</a></li>
-
-<li class="indx">Spiral vessels, illustrations of, <a href="#Page_129">129</a>, <a href="#Page_130">130</a></li>
-
-<li class="indx">Spongy parenchyma of klip buchu, <a href="#Page_260">260</a></li>
-
-<li class="indx">Stage micrometer, <a href="#Page_19">19</a></li>
-<li class="isub1">illustration, <a href="#Page_19">19</a></li>
-
-<li class="indx">Staining dish, <a href="#Page_40">40</a></li>
-<li class="isub1">illustration, <a href="#Page_40">40</a></li>
-
-<li class="indx">Standardization of ocular micrometer, <a href="#Page_19">19</a></li>
-
-<li class="indx">Starch grains, illustrations of, <a href="#Page_186">186</a>, <a href="#Page_187">187</a>, <a href="#Page_189">189-193</a></li>
-
-<li class="indx">Steinheil lens, <a href="#Page_5">5</a></li>
-<li class="isub1">illustration, <a href="#Page_5">5</a></li>
-
-<li class="indx">Stems, diagnostic structures of, <a href="#Page_233">233</a></li>
-<li class="isub1">dicotyledonous, <a href="#Page_233">233</a></li>
-<li class="isub1">herbaceous, <a href="#Page_233">233</a></li>
-<li class="isub1">monocotyledonous, <a href="#Page_233">233</a></li>
-
-<li class="indx">Stomata, ærating function of, <a href="#Page_151">151</a></li>
-<li class="isub1">illustrations of cross-section, <a href="#Page_156">156</a></li>
-<li class="isub1">relation to surrounding cells, <a href="#Page_154">154</a></li>
-<li class="isub1">types of, <a href="#Page_153">153</a></li>
-
-<li class="indx">Stone cells, of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">branched, <a href="#Page_109">109</a></li>
-<li class="isub1">branched, illustrations of, <a href="#Page_110">110</a></li>
-<li class="isub1">description, in, <a href="#Page_112">112</a></li>
-<li class="isub1">introduction, <a href="#Page_109">109</a></li>
-<li class="isub1">occurrence, illustrations, <a href="#Page_115">115</a></li>
-<li class="isub1">porous and non-striated, <a href="#Page_111">111</a></li>
-<li class="isub1">porous and non-striated, illustrations of, <a href="#Page_114">114</a></li>
-<li class="isub1">porous and striated, <a href="#Page_109">109</a></li>
-<li class="isub1">porous and striated, illustrations of, <a href="#Page_113">113</a></li>
-<li class="isub1">storage function of, <a href="#Page_178">178</a></li>
-
-<li class="indx">Storage cavities, <a href="#Page_176">176</a></li>
-<li class="isub1">cavities, illustrations of, <a href="#Page_177">177</a></li>
-<li class="isub1">cells, <a href="#Page_173">173</a></li>
-<li class="isub1">cells, cortical parenchyma, <a href="#Page_173">173</a></li>
-<li class="isub1">cells, illustrations of, <a href="#Page_174">174</a></li>
-<li class="isub1">cells, pith parenchyma, <a href="#Page_173">173</a></li>
-<li class="isub1">cells, wood parenchyma, <a href="#Page_173">173</a></li>
-<li class="isub1">tissue, <a href="#Page_173">173</a></li>
-<li class="isub1">walls, description of, <a href="#Page_179">179</a></li>
-
-<li class="indx">Stored mucilage and resin, illustrations of, <a href="#Page_175">175</a></li>
-
-<li class="indx">Surrounding cells, arrangement of, <a href="#Page_154">154</a></li>
-
-<li class="indx">Synthetic tissue, introduction, <a href="#Page_163">163</a></li>
-
-
-<li class="ifrst">Temporary mounts, <a href="#Page_41">41</a></li>
-
-<li class="indx">Testa cells, <a href="#Page_65">65</a></li>
-<li class="isub1">epidermal cells, illustrations, <a href="#Page_64">64</a></li>
-
-<li class="indx">Tracheids of pink root, <a href="#Page_221">221</a></li>
-
-<li class="indx">Trailing arbutus leaf, cross-section, illustration of, <a href="#Page_266">266</a></li>
-
-<li class="indx">Tripod magnifier, <a href="#Page_4">4</a></li>
-<li class="isub1">illustration, <a href="#Page_4">4</a></li>
-
-<li class="indx">Turntable, <a href="#Page_46">46</a></li>
-<li class="isub1">illustration, <a href="#Page_47">47</a></li>
-
-
-<li class="ifrst">Under epidermis of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">epidermis of mountain laurel, <a href="#Page_264">264</a></li>
-<li class="isub1"><span class="pagenum" id="Page_305">[305]</span>of trailing arbutus, <a href="#Page_264">264</a></li>
-<li class="isub1">hypodermis of klip buchu leaf, <a href="#Page_262">262</a></li>
-<li class="isub1">palisade parenchyma of klip buchu leaf, <a href="#Page_262">262</a></li>
-
-<li class="indx">Unicellular clustered hairs, <a href="#Page_72">72</a></li>
-<li class="isub1">clustered hairs, illustrations, <a href="#Page_71">71</a></li>
-<li class="isub1">non-glandular hairs, <a href="#Page_69">69</a></li>
-<li class="isub1">solitary branched hairs, <a href="#Page_72">72</a></li>
-<li class="isub1">solitary hairs, illustrations, <a href="#Page_70">70</a></li>
-
-<li class="indx">Upper palisade parenchyma of klip buchu leaf, <a href="#Page_260">260</a></li>
-<li class="isub1">palisade parenchyma of mountain laurel, <a href="#Page_264">264</a></li>
-
-
-<li class="ifrst">Vacuoles, <a href="#Page_53">53</a></li>
-
-<li class="indx">Vascular bundles, arrangement of, <a href="#Page_292">292</a></li>
-<li class="isub1">occurrence of, <a href="#Page_292">292</a></li>
-
-<li class="indx">Vessels, annular, <a href="#Page_127">127</a></li>
-<li class="isub1">and tracheids, introduction, <a href="#Page_126">126</a></li>
-<li class="isub1">in cross-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">in radial-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">in tangential-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_237">237</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">pitted, <a href="#Page_131">131</a></li>
-<li class="isub1">pitted with bordered pores, <a href="#Page_131">131</a></li>
-<li class="isub1">reticulate, <a href="#Page_131">131</a></li>
-<li class="isub1">sclariform, <a href="#Page_128">128</a></li>
-<li class="isub1">spiral, <a href="#Page_127">127</a></li>
-
-
-<li class="ifrst">Water pores, aerating function of, <a href="#Page_151">151</a></li>
-
-<li class="indx">Watchmaker’s loupe, <a href="#Page_4">4</a></li>
-<li class="isub1">illustration, <a href="#Page_4">4</a></li>
-
-<li class="indx">Wood fibres, color of, <a href="#Page_104">104</a></li>
-<li class="isub1">illustrations, <a href="#Page_105">105</a></li>
-<li class="isub1">in cross-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">in radial-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">in tangential-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">introduction, <a href="#Page_104">104</a></li>
-<li class="isub1">structure of, <a href="#Page_104">104</a></li>
-
-<li class="indx">Wood parenchyma, conduction by, <a href="#Page_150">150</a></li>
-<li class="isub1">in cross-section of quassia wood, <a href="#Page_254">254</a></li>
-<li class="isub1">in radial-section of quassia wood, <a href="#Page_258">258</a></li>
-<li class="isub1">of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_227">227</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_237">237</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-
-<li class="indx">Woods, description of, <a href="#Page_254">254</a></li>
-<li class="isub1">diagnostic structures of, <a href="#Page_258">258</a></li>
-
-<li class="indx">Woody stems, buchu stem, description  of, <a href="#Page_242">242</a></li>
-<li class="isub1">mature buchu stem, <a href="#Page_242">242</a></li>
-
-
-<li class="ifrst">Xylem, of pink root, <a href="#Page_221">221</a></li>
-<li class="isub1">of ruellia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of ruellia root, <a href="#Page_223">223</a></li>
-<li class="isub1">of ruellia stem, <a href="#Page_237">237</a></li>
-<li class="isub1">of spigelia rhizome, <a href="#Page_226">226</a></li>
-<li class="isub1">of spigelia stem, <a href="#Page_235">235</a></li>
-</ul>
-
-<hr class="chap x-ebookmaker-drop" />
-
-<div class="chapter"></div>
-
-<div class="transnote">
-<p class="center bold">Transcriber’s Notes</p>
-
-<div class="blockquota">
-<p>The Table of Illustrations at the beginning of the book was created by the transcriber.</p>
-
-<p>Inconsistencies in hyphenation such as “extra-ordinary”/“extraordinary”
-have been maintained.</p>
-
-<p>Minor punctuation and spelling errors have been silently corrected
-and, except for those changes noted below, all misspellings in the
-text, especially in dialogue, and inconsistent or archaic usage,
-have been retained.</p>
-</div>
-
-<ol>
-<li><a href="#tn53">Page 53</a>: “The outer portion of the nucelus” changed to “The outer portion of the nucleus”.</li>
-
-<li><a href="#tn54">Page 54</a>: “the centre of the nucelus” changed to “the centre of the nucleus”.</li>
-
-<li><a href="#tn62">Page 62</a>: “typical forms of arrangement of epidermal calls” changed to “typical forms of arrangement of epidermal cells”.</li>
-
-<li><a href="#tn104">Page 104</a>: “of logwood and santalum rubum” changed to “of logwood and santalum rubrum”.</li>
-
-<li><a href="#tn107">Page 107</a>: “the cross-section of catnip stem (<i lang="la" xml:lang="la">Nepeta cateria</i>” changed to “the cross-section of catnip stem (<i lang="la" xml:lang="la">Nepeta cataria</i>”.</li>
-
-<li><a href="#tn120">Page 120</a>: “Cross-section sarsaparilla root (<i lang="la" xml:lang="la">Smilex officinalis</i>” changed to “Cross-section sarsaparilla root (<i lang="la" xml:lang="la">Smilax officinalis</i>”.</li>
-
-<li><a href="#tn150">Page 150</a>: “cells are the narrowest parenchyma cells occuring” changed to “cells are the narrowest parenchyma cells occurring”.</li>
-
-<li><a href="#tn155">Page 155</a>: “Upper epidermis of deer tongue (<i lang="la" xml:lang="la">Trilisia odoratissima</i>” changed to “Upper epidermis of deer tongue (<i lang="la" xml:lang="la">Trilisa odoratissima</i>”.</li>
-
-<li><a href="#tn171">Page 171</a>: “Parenchyma cells with protuding” changed to “Parenchyma cells with protruding”.</li>
-
-<li><a href="#tn193">Page 193</a>: “grains of paradise (<i lang="la" xml:lang="la">Amomum meleguetta</i>” changed to “grains of paradise (<i lang="la" xml:lang="la">Amomum melegueta</i>”.</li>
-
-<li><a href="#tn237">Page 237</a>: “Marrubium perigrinum, which is a related species of horehound” changed to “Marrubium peregrinum, which is a related species of horehound”.</li>
-</ol>
-</div>
-
-<div style='display:block; margin-top:4em'>*** END OF THE PROJECT GUTENBERG EBOOK HISTOLOGY OF MEDICINAL PLANTS ***</div>
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