1M8
■
;: Jpr
it'.IHI'
W\t -0. p. J!tU phrarg
•»♦•
QH506
fif>7
N.C. STATE UNIVERSITY D.H. HILL LIBRARY
S00366687
Date Due
•-
Feb23'34
L
Wf
19Ar>J1C
~
\
FEB 1
7 1QA?
MAY
vm
19750
«ne as ?&5 l^RLZZ^
200M/06-99-991212
Elms at the Water's Brink.
PRACTICAL BIOLOGY
BY
W. M. SMALLWOOD
SYRACUSE UNIVERSITY
IDA L. REVELEY
WELLS COLLEGE
GUY A. BAILEY
GENESEO STATE NORMAL SCHOOL
-oojojoc-
ALLYN AND BACON
Boston Neto gork Chicago
COPYRIGHT, 1916, BY
W. M. SMALLWOOD, IDA L. REVELEY
AND GUY A. BAILEY
ADR
Notijjooli UJregg
J. S. Cushing Co. — Berwick & Smith Co.
Norwood, Mass., U.S.A.
(
PREFACE
Practical Biology offers a simple, workable, attractive,
flexible, and teachable course in Biology.
Simplicity is a feature of the book. The language is simple,
not technical, and the style is easy, flowing, and colloquial.
The pupil is assisted by many mechanical helps. Small cuts
or larger pictures illustrate each new topic and there are many
charts and maps.
The practical aspects of Biology are emphasized. A study
is made of the economic value of plants and animals, and of
the characteristics which make them beneficial or harmful to
mankind. *
The attractive illustrations, many of which were made es-
pecially for the book, are a feature of the Biology. In addi-
tion to the cuts and pictures which illustrate the text, there
are portraits of the leading biologists of the world, with brief
accounts of their lives and of their contributions to the subject.
The flexibility of the book enables teachers to begin with
the study of animals or with the study of plants.
A number of features help to make Practical Biology teach-
able, (a) The paragraphs are short, and there are summaries
and questions at the end of each chapter, (b) Well-known
types like the grasshopper and the bean plant are studied first,
and the treatment passes from the known to the unknown,
(c) The pronunciation and derivation of technical names are
given in the text the first time the names occur, (cl) There is
an introduction defining the common scientific terms used in
the study of Biology, (e) Optional field work and students'
reports are provided for. (/) Laboratory work is contained
iii
iv PREFACE
in the book, so that a special manual is unnecessary, (g) The
index is unusually complete.
The treatment of human biology emphasizes hygiene and
sanitation and contains graphic diagrams illustrating the sec-
tions on health and disease. This treatment will be found
especially practical. The treatment of alcohol and narcotics
is adequate, but sane.
For teachers in New York State a feature of the book is its
close relation to the Regents' Syllabus, which it covers exactly.
It is equally suited to courses laid down for various other
states, notably Massachusetts and Ohio.
The book has a number of appendices, one of which has
to do with bird study. Another contains the sanitary code of
the State of New York.
The work is so arranged that the course, though simple, is
thoroughly scientific. Science is organized knowledge, and
the simple student reports in the form of tables lead the pupil
to make a correct and logical classification of his facts, thus
laying the foundation for scientific study.
W. M. S.
I. L. R.
G. A. B.
July, 1916.
ACKNOWLEDGMENT OF ILLUSTRATIONS
Guy A. Bailey, Bird and Mammal Photographs (in nature).
Fred Baker, New York State College of Forestry, 406.
Hugh P. Baker, New York State College of Forestry, 411, 414.
M. W. Blackmail, New York State College of Forestry, 2, 127,
128.
S. S. Berry, 100.
G. Sidney Britton, Syracuse, N. Y., 145, 146.
W. E. Britton, Connecticut, Agriculture Station, 27.
W. Coe, Yale University, 73, 74.
Conservation Commission, N. Y. State, 412, 413, 415, 416, 417,
418, 419, 420.
Hugh Findlay, College of Agriculture, Syracuse University,
17, 18, 308, 330, 348, 355, 357, 358, 359, 362, 435, 436, 437.
Hugh Findlay and Dr. I. H. Levy, 346, 441.
Fitzhenry-Guptill Co., Boston, 16.
Geneva Experimental Station, N. Y., 383, 384, 385.
Illinois State Laboratory of Natural History, 430, 431.
J. E. Kirkwood, University Montana, 1.
Dr. J. S. Marshall, Berkeley, Cal., 182, 183.
D. F. MacDougal, Desert Laboratory, Tucson, Arizona, 432.
S. O. Mast, Johns Hopkins University, 49.
N. Y. State Bureau of Health, 238, 242, 243, 244, 245.
Dr. Edward Packard, Saranac Lake, N. Y., 239, 240.
Parrott and Fulmer, Geneva Experimental Station, N. Y., 10.
F. C. Paulmier, Albany, N. Y., 87, 88.
Dr. C. Potter, Syracuse, N. Y , 185, 186, 195, 196, 197, 198, 199.
L. Pennington, New York State College of Forestry, Syracu^ .
N. Y., 380, 381, 382.
v
VI ACKNOWLEDGMENT OF ILLUSTRATIONS
A. M. Reese, University West Virginia, Morgantown, W. Va.,
133, 134.
A. G. Rutheven, University Michigan, Ann Arbor, 131, 132.
G. B. Simpson, Albany, N. Y., 14, 93, 94, 95.
B. G. Smith, Ypsilanti, Michigan, 113.
W. H. Snyder, Los Angeles, 42, 123, 135, 159, 167, 176, 177,
222, 241, 280, 433, 440.
Syracuse Universit}^, Agricultural College, 246, 247.
Crystal Thompson, Ann Arbor, Michigan, 114.
J. M. Thorburn & Co., New York City, 220, 278, 279, 297, 298,
329, 361, 378.
C. H. Townsend, N. Y. Aquarium, 105, 106, 107, 108.
U. S. Census 1910, 248, 340, 343, 344, 352, 356.
U. S. Department of Agriculture, 7, 9, 11, 12, 13, 19, 33, 34,
35, 37, 38, 39, 43, 44, 56, 85, 96, 102, 103, 111, 112, 171,
172, 173, 269, 270, 290, 293, 294, 295, 315, 337, 345, 349.
Jerome Walker, Physiology, 213, 220, 221.
Anti-Saloon League, 230, 231, 232, 234.
TABLE OF CONTENTS
PART I
ANIMAL BIOLOGY
PAGE
Introduction 1
CHAPTER
I. The Grasshopper. A Representative Animal . . .11
II. Other Common Insects 24
III. The Simplest Animals — Protozoa 45
IV. The Simpler Metazoa 55
V. Ccelenterates, Hydra-like Animals 63
VI. The Starfish Family. (Optional) 71
VII. The Worm Group 76
VIII. Crustaceans and Related Forms 86
IX. The Mollusks 94
X. Fishes 103
XI. Amphibians 113
XII. Reptiles 129
XIII. Birds 136
XIV. Mammals 150
PART II
HUMAN BIOLOGY
XV. Life Processes of Man 161
XVI. The Skeleton and Muscles . . . . . . .184
XVII. Respiration, Blood, and Excretion 192
XVIII. The Nervous System of Man . ... 209
XIX. The Biology of Disease .... ... 232
19722
vm
TABLE OF CONTENTS
PART III
PLANT BIOLOGY
CHAPTEE PAGE
XX. Typical Flowering Plants ....... 259
XXI. Other Flowering Plants 323
XXII. The Simplest Plants 338
XXIII. The Smallest Plants (Bacteria) ...... 343
XXIV. Fungi 354
XXV. Mosses and Their Allies 364
XXVI. Ferns and Their Allies 369
XXVII. The Conifers (Gymnosperms) 376
XXVIII. Peculiarities of Plant Life ....... 389
Appendix A 405
Bird Study.
Appendix B 408
Sanitary Code of New York.
Appendix C ...... <> ...» 414
Cancer.
LIST OF ILLUSTRATIONS
Elms at the Water's Brink Frontispiece
FIGURE PAGE
1. Simple Osmometer 3
2. Plant Cell 4
3. Animal Cell 4
4. Tissue ............ 5
5. Diagram : Showing proportion of chemical elements in living
things 8
6. Female Grasshopper 11
7. Diagram : Showing main parts of the grasshopper ... 13
8. Mouth Parts of the Grasshopper . . . . . . .14
9. Grasshopper Laying Eggs . . . . . . . .15
10. Incomplete Metamorphosis of the Tree Cricket .... 17
11. Codling Moth Larva 17
12. The Worm in the Apple 18
13. Codling Moth Pupa . 18
14. Codling Moth 19
15. Monarch Butterfly 20
16. Modern Spraying Outfit 21
17. Plant Lice on Fern 24
18. Mealy Bug 25
19. Cicada, Adult and Nymph 25
20. May Beetle 26
21. Eggs of Ladybug ........ 26
22. Holes Made by Woodpeckers ...... 27
23. Redheaded Woodpecker 28
24. Larva of Mourning Cloak Moth 28
25. Transformation of Pupa of Mourning Cloak Moth into Adult . 29
26. Cecropia Moth 30
27. Young Tobacco Worm . ... 30
28. Larvae of a Leaf Miner • • .31
29. Cedar Bird
30. A Geometrid Moth ..... . .32
31. Protective Coloration 33
32. Yellow Swallowtail . 33
ix
X LIST OF ILLUSTRATIONS
FIGURE PAGE
33. Honey Bee : Worker ; Queen ; Drone 34
34. Queen Cell 35
35. Honey Bee Egg ; Young Larva; Old Larva ; Pupa ... 35
36. Honey Bees Clustering at Swarming Time 36
37. Capturing a Swarm 37
38. Model Apiary 38
39. Cutting Combs from Box Hive 39
40. Ichneumon Flies 40
41. Adult Horn-Tailed Saw-Fly 40
42. Common Housefly 41
43. Eggs and Larvae of Culex 42
44. Adult Culex ; Adult Anopheles 42
45. Microphotograph of an Amoeba ....... 47
46. Diagram of an Amoeba 48
47. Amoeba Reproducing by Fission .49
48. Diagram of Paramoecium 50
49. Paramoecium 51
50. Paramoecium Reproducing by Fission 51
51. Vorticella 52
52. One of the Foraminfera . 52
53. Some Flagellate Protozoa 52
54. Gonium . . . . . . . . ... .55
55. Volvox 56
56. Bath Sponge 58
57. Diagram : Showing parts of sponge ...... 59
58. Spicules of Lime 59
59. Two Stages in the Development of the Sponge 60
60. Microphotographs of Hydra 63
61. Diagram of Body of Hydra . 64
62. Microphotograph of Body Wall of Hydra 64
63. Diagram of Cell Layers ........ 65
64. Microphotograph of the Hydroid Obelia 66
65. Diagram of the Hydroid Bougainvillea 66
66. A Hydroid Colony that Looks Like a Plant 67
67. A Hydroid Medusa 67
68. The Medusa Known as Pelagia '67
69. Pennaria Tiarella . 68
70. Some Common Corals . 69
71. Starfish 71
72. Diagram of Body of Starfish 72
73. Anatomy of the Starfish 72
74. Purple Sea Urchin 74
LIST OF ILLUSTRATIONS XI
FIGURE PAGE
75. Sea Lily . , . 74
76. A Planarian Worm 77
77. Trichinella 78
78. A Common Tapeworm ........ 78
79. Hair Worm in the Body of a Grasshopper .... 79
80. Diagram of the Organs of Earthworm from the Side . . 81
81. Earthworm . 82
82. Dero 84
83. Crayfish Bearing Eggs ........ 86
84. Crayfish . ' . 87
85. Molted Exoskeleton of Lobster 87
86. Organs of Crayfish 89
87. Soft-Shell Crab 91
88. Pill Bug . 91
89. Cyclops . . .... ... 91
90. Daddy-Long-Legs ..... ... 92
91. Spider 92
92. Thousand-legged Worm ; Centipede ..... 92
93. Clam ; Showing Foot 94
94. Right Shell of Clam 95
95. Digestive Tube of Clam 95
96. Embryo of Clam 97
97. Snail 98
98. Tongue of Snail 98
99. Snail Shells 99
100. An Octopus 99
101. Soft-Shell Clam 100
102. Stages in Life History of Oyster 101
103. Barnacles and Clams Growing on Oysters . . . .101
104. Skeleton of Fish . 103
105. Perch 104
106. Sunfish, or Pumpkin Seed .104
107. Catfish, Bullhead, or Horned Pout . . . . . .105
108. Brook Trout 106
109. Scales of Fishes . . . . ■ 107
110. Eggs of Land-Locked Salmon 110
111. Young Fish ; Showing Yolk Sac .111
112. Young Fish Fry Ill
113. Some Common Salamanders 113
114. Common Frog 114
115. Diagram to Show Organs of Frog 116
116. Kidneys of the Frog .... . .117
Xll LIST OF ILLUSTRATIONS
FIGURE PAGE
117. Central Nervous System of Frog . ... 118
118. Frog Eggs : ... 121
119. Diagram Illustrating Fertilization in Frog Egg . . . .121
120. Dividing Egg of Frog 122
121. Dividing Egg Becoming a Tadpole 122
122. Two Stages in the Development of Tadpoles .... 123
123. Fossil Shells of Animals Now Extinct 124
124. Tree Frog 126
125. A Sea Turtle 129
126. Horned Toad, a Lizard 129
127. Bull Snake with Hen's Egg in Mouth 130
128. Bull Snake after Swallowing Egg 130
129. Head of Rattlesnake 131
130. Rattles of Rattlesnake 131
131. Rattlesnake — Poisonous 132
132. Garter Snake — Harmless 133
133. Eight-Foot Florida Alligator ....... 133
134. Alligator Nest 134
135. Poisonous Lizards ; the Gila Monster 135
136. Grebe . . ... . • 136
137. Herring Gulls 137
138. Adult Screech Owl 138
139. Skeleton of Mallard Duck .138
140. Different Kinds of Birds' Feet ....... 139
141. Loggerhead Shrike 139
142. Young of Red-Tailed Hawk — Beneficial ..... 140
143. Head of Young Eagle 140
144. The Robin 141
145. Nest of Yellow Warbler 142
146. Nest of Bittern 142
147. Mourning Dove . .143
148. Chimney Swift and Nest „ 144
149. Junco . 144
150. Female Bobolink 145
151. King Bird . 145
152. Young Crows in Nest 146
153. Kingfisher 146
154. Hairy Woodpecker Eating Suet 147
155. Male and Female Cowbirds 147
156. Plan for Bird House 148
157. Plan for Bird House .148
158. Skeleton of Dog . 150
LIST OF ILLUSTRATIONS
Xlll
KIGl'RE
Leaving Its Nest
Deer
159. Coyote
160. Gray Squirrel
161. Young Gray Squirrel
162. Young Foxes
163. Bat Hibernating
164. Brown Bat
165. Flying Squirrel .
166. Deer Mouse
167. Sea Lions .
168. Stomach of Sheep
169. Skunk
170. Young Rabbits .
171. Elk .
1 72. Virginia Deer
173. Fawns of the Virginia
174. Coon .
175. Young Woodchucks
176. Camel ; the Ship of the Desert
177. Buffalo ....
178. Alimentary Canal of Frog .
179. Alimentary Canal of Man .
180. Tongue ....
181. Taste Cells
182. Milk Teeth
183. Permanent Teeth
184. Pear-Shaped Human Stomach
185. X-Ray Photograph of Human Stomach
186. X-Ray Photograph of Appendix and Part o
187. Gastric Gland .....
188. Microphotograph of Stomach
189. Diagram of Villus ....
190. Home-Made Apparatus to Show Osmosis
191. Skeleton
192. Microphotograph of Bone .
193. Diagram of Bone Structure
194. Cartilage
195. X-Ray of a Normal and a Broken Elbow
196. X-Ray of Hand of Child .
197. X-Ray of Hand of Adult .
198. Broken Femur .....
199. Same Bone Ten Weeks Later .
200. Muscles of Upper Leg
f Large In
testine
PAGE
150
151
151
151
151
152
152
153
153
154
154
154
155
156
156
157
157
158
158
163
165
165
165
166
167
168
168
169
169
170
174
175
184
185
185
185
185
186
186
187
187
188
XIV
LIST OF ILLUSTRATIONS
FIGURE
201. Voluntary Muscle Cells
202. Involuntary Muscle Cells .
203. Heart Muscle Cells ....
204. Various Forms of Cells in Human Body
205. Diagram of Skin ....
206. Lungs and Heart ....
207. Voice Box, or Larynx
208. Diagram of the Diaphragm
209. Hot-Air Heating ....
210. Steam Heating
211. Microphotograph of Blood of Frog
212. Diagram of Work of the Capillaries .
213. Organs of Circulation
214. Heart
215. Diagram of Vein ....
216. Diagram of Capillaries
217. Main Arteries of Frog
218. Main Arteries of Man
219. Superficial- Lymphatics of Arm and Hand
220. Section of Kidney ....
221. Diagram showing Artery, Vein, and Kidney Tube
222. Nervous System of Man
223. Nerve Cells
224. Nerve Cells
225. Microphotograph of Brain .
226. Diagram to show Reflex Action
227. Section of Eye ....
228. How We See the Pencil
229. Plan of Ear
230. Statistics : Skill and Endurance Impaired by Drink
231. Statistics: Drink Impaired Scholarship
232. Statistics : Assaults and Drink .
233. Brain Control
234. Statistics : Abstainers' Advantage
235. Chart on Smoker's Heart (I)
236. Chart on Smoker's Heart (II)
237. Chart on Smoker's Heart (III) .
238. Deaths from Communicable Diseases
239. Tuberculosis Cure, Summer
240. Tuberculosis Cure, Winter
241. Malarial Swamp ....
242. A Model Reservoir ....
LIST OF ILLUSTRATIONS
XV
FIGURE
243. A Poor Reservoir
244. Diagram : Thirty Years of Diphtheria in New York State
245. Diagram : Story of Epidemic of Septic Sore Throat at Rockville
Centre, L. I.
246. Model Dairy Cow
247. Model Dairy Stable .
248. Map Showing Number of Dairy Cows on
April 15, 1910
Agar Plates
Bacteria and Mold
249.
250.
251.
252.
253.
254.
255.
256.
257.
258.
259.
260.
261.
262.
263.
264.
265.
266.
Milk Diluted to j^Vo
Bean Plant ....
Photograph of Bean and Pea
Parts of Bean Seed
Diagram of Corn Seed
Sunflower Seed .
Squash Seed
Germination of Bean .
Bean Plants
Sections of Bean Root
Root Hairs ....
Root Cap ....
Bean Roots
Fibrous Roots of Buttercup
Cross Section of Bean Leaf
Leaf Skeleton
267. Epidermis of Leaf
268. Germination of Corn .
269. Rootlets of Two Corn Plants
270. Corn Plant ....
271. Maple Seedlings .
272. Microphotograph of Corn Stem
273. Stem of Corn
274. Older Maple Seedlings
275. Seedlings ....
276. Older Horse-Chestnut Seedlings
277. Wheat Seedlings
278. Roots of Radish .
279. Roots of Beet
280. Alfalfa Root
281. Aerial Roots of Ivy
282. Potato
Farms and Ranges
i'aci:
241
242
243
247
248
249
250
251
252
259
260
260
262
262
262
264
267
268
269
269
270
271
273
273
274
277
277
278
279
279
280
280
281
281
28?
282
283
283
284
285
XVI
LIST OF ILLUSTRATIONS
308.
309.
310.
311.
312.
313.
314.
315.
316.
317.
318.
319.
320.
321.
322.
323.
FIGURE
283. Dahlia Roots .....
284. Microphotograph of Sunflower Stem .
285. Cleft Grafting .....
286. Whip Grafting
287. Budding ......
288. Twining Stem of Dodder .
289. Creeping Stem of Trailing Arbutus
290. Horse-Chestnut ....
291. Types of Twigs .....
292. Cherry Twigs .
293. Sections of Woody Stem
294. Wood of Spruce
295. Photograph of Sections of Wood
296. Food Storage
297. Celery Plant
298. Cabbage Plant
299. Twining Petiole of Clematis
300. Twining Petiole of Nasturtium .
301. Barberry Leaves ....
302. Pea Plant
303. Leaf of Oak
304. Leaf of Elm
305. Diagram of Bean Flower .
306. Diagram of Stamen and Pistil .
307. Sweet Pea Flower ....
Fly Pollinating Wild Carrot
Swallow-Tail Butterfly Pollinating Persian
Corn Flower with Pistils
Pollen Grains .....
Pistillate and Staminate Flowers of Willow
Violet
Two-Parted Flower of Mint
Lady Slipper
Flower of Columbine ....
Salvia
Easter Lily ......
Fruit of the Bean ....
Fruit of the Corn
Fruit of the Poppy
Capsule of Violet
Chestnuts .
324. Dry Fruits
Lilacs
PAGE
285
286
286
287
287
288
288
288
289
289
289
290
290
291
292
292
292
292
293
294
294
294
296
297
298
298
299
299
300
301
301
303
303
304
306
306
307
307
303
308
308
309
LIST OF ILLUSTRATIONS
XV11
FIGURE
325.
Vertical Section of Apple .
326.
Cross Section of Apple
327.
Cross Section of Orange
328.
Forms of Dehiscent Fruits
329.
Fruits with Hooks
330.
Burdock in Blossom .
331.
Fruits Distributed by Wind
332.
Other Fruits Distributed by Wind
333.
Fruits and Seeds
334.
Milkweed Plant ....
335.
Seed of Cotton ....
336.
Bean Plant Injured by Bacteria .
337.
Beans Damaged by Weevils
338.
A Field of Beans
339.
Peanuts
340.
Map of Corn Production
341.
Walnut Tree
342.
Map of Production of Oats
343.
Map of Wheat Production
344.
The Cereals
345.
Lily-of-the-Valley
346.
X-Ray of Easter Lily .
347.
Leaves and Bud of Beech
348.
Wild Columbine .
349.
Stamens and Pistils of Rose
350.
Rose Flower Turning into a Fruit
351.
Thorns of Rose ....
352.
Map of Production of Orchard Fruits
353.
Stipules of Rose Leaf .
354.
Flower of Mallow
355.
Water Horehound
356.
Map of Cotton Production .
357.
Self-Heal .
358.
Hedge Nettle
359.
Common White Daisy
360.
Dandelion .
361.
Map of Potato Production
362.
Canada Thistle .
363.
Pleurococcus
364.
Spirogyra .
365.
Spirogyra Conjugating
366. Microphotograph of Conjugating Spirogyra
PAGE
309
309
310
310
311
311
312
312
312
313
313
315
315
317
318
319
323
324
325
326
326
327
327
328
328
329
329
330
331
331
331
332
333
333
334
334
335
336
338
340
340
341
XV111
LIST OF ILLUSTRATIONS
FIGURE
367. Forms of Bacteria
368. Soil Bacteria
369. Clean Milk .
370. Dirty Milk .
371. Beef Jelly .
372. Beef Jelly .
373. Bad and Good Bottling
374. Yeast ....
375. Fermentation Tubes .
376. Bread Mold
377. Mold Grown from Water
378. Cap Fungi .
379. Puffballs .
380. Puffballs .
381. Bracket Fungus .
382. Tree Killed by Bracket Fungus
383. Pear Scab .
384. Section through the Scab
385. Spores
386. Lichens .
387. Section of Lichen
388. Spores of Corn Smut .
389. Types of Mosses .
390. Diagram : Life History of Moss
391. Antheridial Plant
392. Archegonial Plant
393. Marchantia .
394. Pteris .
395. Pteris Stem
396. Sori .
397. Sori Enlarged
398. Forked Veins of Fern
399. Sporangia .
400. Position of Sori ; Section of Sorus
401. Life History of Fern .
402. Sporangium ; Spores .
403. Club Moss .
404. Horsetail
405. Selaginella .
406. Conifers
407. Staminate Strobili of Pine
408. Young Cone of Pine .
PAGE
343
344
348
349
350
351
352
355
355
357
357
357
358
358
359
359
359
359
360
361
361
362
364
365
365
365
367
369
370
370
370
371
371
372
372
373
373
374
374
376
377
377
LIST OF ILLUSTRATIONS
XIX
Pennsylvania
FIGURE
409. Ripe Cone of Pine
410. Other Cones
41 1. Forest of Hard Woods and Conifers in Northern
412. Lumbering in New York ....
413. Fire Slash .......
414. Waste Land in Pennsylvania
415. Waste Land
416. Fire Train in Adirondacks ....
417. Nursery where Young Trees are Started
418. Planting Young Trees in the Adirondacks .
419. Young Plantation in the Adirondacks .
420. Young Plantation Sixteen Years after Planting
421. Pollen of Pine .
422. Seed of Pine
423. Photograph of Pitcher Plant
424. Leaves of Pitcher Plant
425. Photograph of Sundew
426. Diagram of Sundew .
427. Venus's Fly-Trap
428. Photograph of Birch Roots.
429. White Waterlily .
430. Waterlilies ; Hydrophytes .
431. Cat-Tails ....
432. Giant Cactus
433. Sage Brush ....
434. Diagram : Showing Epidermis o
435. Bull Thistle
436. Lady Slipper
437. Long-Spurred Violet .
438. Mistletoe ....
439. Diagram of Sectional View of a Branch Infected with Mistletoe
440. Tropical Vegetation
441. CallaLily ....
Agave, a Zerophytic Plant
PAGE
378
378
379
380
380
381
381
382
382
384
385
386
387
387
389
390
390
391
391
392
392
393
394
395
395
396
396
397
397
398
399
401
403
PORTRAITS OF PROMINENT BIOLOGISTS
Darwin
Agassi z
Huxley
Koch .
Linnaeus
Pasteur
IM IM. v \..r
. 30
. 100
. 170
. 235
. 303
. 348
INTRODUCTION
DEFINITIONS OF COMMON BIOLOGICAL TEEMS
Biology is the science which discusses living things — ■
plants, the lower animals, and man. These living things
move, breathe, feel, and get their food in varied ways.
Man, for instance, does not move as a jellyfish moves,
nor does he breathe as a tree breathes. He has not the
same sensations as a frog, nor does he get his food as do
the flowers ; though lie and all other living things have
these functions1 in common. Each living thing has its
parts especially adapted to its peculiar needs. Claws
serve a cat admirably for climbinor and for catching mice;
a frog has web feet to aid in swimming ; while hands are
better suited to the kind of things that a man has to do.
Energy. — Everything that plants and animals do re-
quires energy. Without energy in some form they can-
not move or grow. Energy is produced in various ways.
In a steam engine fuel is consumed or oxidized to make
energy. In man the food taken into the body is con-
verted into energy by a slow kind of burning which we
call oxidation.
Life Processes. — From the study of physiology we are
fairly familiar with foods, or nutrients, as they are some-
times called. Some of these are starch, sugar, fats, oils,
and mineral matter. The life of a plant or of an animal is
directly dependent upon its food. But food is not the
1 Function has a scientific use in biology, where it is used to describe the
common living activities of animals and l>'antMMMMH7 f Bwn
1 * C State Oik*
2 INTRODUCTION
only important thing to consider in studying its life.
The life of each plant or animal may be studied under
eight headings, known as life processes. These are sensa-
tion or irritability, locomotion, food getting, digestion, assimi-
lation, respiration, excretion, and reproduction.
1. Sensation (irritability') is that life process by means
of which an organism comes to know of things outside of
itself. Through sensation (irritability) it becomes aware
of its food. By the help of the senses the higher animals
are able to see and hear one another, are conscious of heat,
cold, light, sound, and many other things, all of which
are called stimuli.
2. Locomotion is the life process by which animals move,
and is closely related to sensation. It is the means by
which animals secure food. In the higher animals stimuli
are sent through the nervous system to the various muscles,
which contract and so cause the animal to move.
3. Food getting needs no definition. Man gets his food
from many sources. He eats animals, minerals, and vege-
tables. Lower animals live by hunting or grazing, and
plants get their food through their leaves and roots.
4. Digestion is the life process which prepares the food
to pass to all parts of the body. It takes place in all
animals and plants, but we are most familar with it in
man. Man chews his food in the mouth, thus softening
it and mixing it with saliva ready for the stomach. Di-
gestion is continued in the stomach and completed in the
intestine.
As soon as the food is digested, some of it passes through
a thin membrane in the wall of the intestine into the
blood vessels and thus is ready to furnish energy in the
body. This passage of the dissolved food through a mem-
brane is called osmosis (os-mo'sis).
5. Assimilation is the building of the digested food
LIFE PROCESSES
into living animal and plant parts. In animals the blood
vessels, into which the digested food passes, carry it to all
parts of the body, and as it circulates,
each part takes the food needed and
builds it into living material.
6. Respiration is the life process that
uses oxygen taken from the air or water
and forms a waste product known as
carbon dioxide. This life process should
not be confused with breathing, which
is limited to animals with lungs or air-
tubes. In such animals the breathing
is simply a mechanical process in which
the air is brought into the lungs or
air-tubes. This allows the oxygen to
pass by diffusion into the blood, where
it is carried to all parts of the body, or
it may pass directly to the living cells.
See section 6, page 14.
7. Excretion is the life process in
which waste products, like perspiration,
are made and cast off by the body. On
page 1 we saw that energy was pro-
duced by oxidation. After this the
waste is thrown off by excretion, as
the ashes are thrown out of a steam
engine.
8. Reproduction is the life process by means of which
each generation of plants and animals is brought forth.
There are two kinds, asexual (a'sex-u-al) and sexual.
Figure 47 on page 49 shows a simple animal, the amoeba
(a-me'ba), dividing into two young amoebae by asexual
methods. The same kind of reproduction in a simple
plant, the yeast, is illustrated in Figure 374, page 355.
Figure 1 . — Simple
Osmometer show-
ing Osmosis.
The water in the
glass passes through
the egg-membrane
and forces the egg-
white up in the glass
tube ; while the egg-
white does not pass
out into the sur-
rounding water.
INTRODUCTION
Figure 2. — Plant Cell.
Sexual reproduction is the name given to a process in
which two special cells, called the egg and the sperm,
unite to form one cell, the
fertilized egg cell. The fer-
tilized egg grows into the
new organism. In some
plants the fertilized egg
forms part of a seed which
later develops into the plant.
These eight life processes
are seen in all forms of liv-
ing things, but it is often
hard to stuclv them. For
instance, the locomotion of a clam is harder to study
than that of a cat, and the respiration of a plant than that
of a man.
The Parts of Bodies. — These life
processes tell us what the parts
of bodies do, but they tell us
nothing about these parts them-
selves. There are four words
which are used in biology to
describe these parts. They are:
cell, tissue, organ, and organ
system.
1. The Cell. —When the bi-
ologist takes apart the plant or
animal as you used to take down
your block houses, he finds that
he can separate the parts until
he comes to a unit so small that
a microscope is necessary to see
it. These microscopic parts are called cells and are
alike in the following respects : each one has a clear
Figure 3. — Animal Cell.
THE PARTS OF BODIES
outer portion called the cell wall which incloses a mass of
substance known as protoplasm (pro'td-plaz'm : Greek,
protos, first; plasma, form). The protoplasm is made up
of a substance called cytoplasm (sl'tu-plaz'm : Greek, kytos,
hollow place ; plasma, form), in which is held a saclike
body, the nucleus (nu/kle-us : Latin, nucleo, to become
hard). The nucleus usually contains one or more separate
bodies called nucleoli (nfi/kle-6-li). A cell is therefore
defined as a mass of protoplasm composed of cytoplasm and
nucleus (Figures 2 and 3).
2. Tissue. — The cells are of many shapes and sizes,
and in the bodies of all but microscopic plants and animals
are united to help the
plant or animal carry
on its life processes.
This union of cells to
do a certain work is
called a tissue, and the
usual definition is : a
tissue is a group of simi-
lar cells that do a similar
work (Figure 4).
3. Organs. — In all of
the higher animals the
tissues are united into
skin, arms, stomach,
and so on, or in plants into leaf, branch, etc. Such struc-
tures are called organs ; an organ is defined as a group of
tissues that do a given work in the animal or plant.
4. The Organ System. — When different organs com-
bine to carry on such a general life process as digestion,
all of the parts that assist in this process are described as
an organ system, as the system of digestive organs (Fig-
ures 178 and 179, pages 163 and 165).
Figure 4. — Tissue.
Compare these cells with Figures 2 and 3.
6 INTRODUCTION
These four expressions, cell, tissue, organ, and organ sys-
tem, describe the materials of plants and animals which
carry on the eight life processes referred to above. We
shall read more and more about them as our study of
biology progresses.
Classification of Living Things. — Our study of biology
cannot progress far before we see the need of classifying
animals and plants. Animals are generally grouped in
two divisions : invertebrates (animals without backbone)
and vertebrates (animals with backbone). Plants are also
divided into two groups : cryptogams (flowerless and seed-
less plants) and phanerogams (flowering or seed-bearing
plants). Below is given a detailed reference table of
these classifications.
I. Invertebrates. Animals without a backbone.
1. Protozoa. 8000 different kinds.
a. Rhizopoda. Example, the amoeba.
b. Ciliata. Example, the paramoecium.
2. Porifera. Sponges, 2500 different kinds. Example, the bath
sponge and grantia.
3. Ccelenterata. Hydra, corals, and jellyfish. 4500 different kinds.
a. Hydrozoa. Example, the hydra, obelia, pennaria.
b. Scyphozoa. The large jellyfishes.
c. Actinozoa. The corals.
4. Echinoderms. Starfishes and sea urchins. 4000 different kinds.
5. Worms and wormlike animals. Examples, flat worms, tape
worms, earthworms. 11,000 different kinds.
6. Mollusca. The clams and snails. 61,000 different kinds.
a. Pelecypoda. Example, clams.
b. Gastropoda. Example, snails.
c. Cephalopoda. Example, squids, devilfish.
7. Arthropoda. Crabs and insects. 400,000 different kinds.
a. Crustacea. Example, crayfish and crabs. 10,000 different
kinds.
b. Insecta. Example, grasshopper, flies, butterflies, bees.
390,000 different kinds.
II. Vertebrates. Animals with a backbone.
1. Fishes. Examples, trout, perch, bass, cod. 13,000 different kinds.
SCIENTIFIC TERMS 7
2. Amphibia. Example, frog, salamander. 14,000 different kinds.
3. Reptilia. Example, snakes, turtles, alligators. 35,000 different
kinds.
4. Birds. Example, sparrow, eagle, hawk, crow. 13,000 different
kinds.
5. Mammals. Example, horse, cow, sheep, monkey, man. 35,000
different kinds.
The plants, like the animals, are arranged in general
groups (phyla) which, beginning with the simplest, are as
follows :
I. Cryptogams. Flowerless or seedless plants.
1. Thallophytes.
a. Bacteria. 1300 different kinds.
b. Algse. Example, pleuroccocus, spirogyra. 1300 different
kinds.
c. Fungi. Example, molds, puff-balls, toadstools. 64,400 dif-
ferent kinds.
2. Bryophytes.
a. Liverworts. 4000 different kinds.
b. Mosses. 12,600 different kinds.
3. Pteridophytes. 4500 different kinds of ferns.
II. Phanerogams. Flowering or seed-bearing plants.
1. Gymnosperms. Example, pine, spruce. 540 different kinds.
2. Angiosperms. Flowering plants proper.
a. Monocotyledons. Example, corn. 23,700 different kinds.
b. Dicotyledons. Example, bean. 108,800 different kinds.
Scientific Terms. — Scientists in America, France, Ger-
many, Russia, and elsewhere are continually studying
different plants and animals. For their convenience the
Latin names are usually adopted in advanced scientific
works. Thus the English or house sparroiv is called .Pasxrr
domesticus, and the American elm, Ulmus americana, so that
scientists of different countries may always use the same
term. But in this book we shall use the common Ameri-
can names of the plants and animals studied.
Scientific terms include also the names of certain suit-
stances frequently referred to in science books like this
8
INTRODUCTION
Nitrogen
Sulphur
Phosphorus
Calcium
etc
Biology. Before going farther it is well to get a clear idea
of what the common chemical terms mean.
1. Oxygen is a gas which makes up a large part of the air.
It is the element in the air which sustains life in animals
and plants. Without it they cannot live. When given
an undue amount of it,
they develop at an ab-
normal rate. It forms
about seventy per cent
of the bodies of plants
and animals.
The most striking
property of oxygen is
the ease with which it
unites with other sub-
stances. Practically all
cases of burning are
caused by oxygen unit-
ing with paper, wood,
coal, or some other material. If a piece of glowing
charcoal is placed in a jar of oxygen, it bursts into flame.
This is the test for oxygen.
2. Carbon is, next to oxygen, one of the most important
elements in biolog}^. It is usually black and solid and is
best seen as the charred remains of any material that has
been overheated but not burned up, as when toast or meat
is " burned." Carbon forms about fourteen per cent of the
body of plants and animals.
3. Hydrogen gas is the lightest of all substances. For
this reason it is used in balloons and Zeppelins. It forms
a little less than ten per cent of the body of plants and
animals.
4. Nitrogen is a gas which — unlike oxygen and hydro-
gen — does not burn. It dilutes the oxygen of the air and
Figure 5. — Diagram.
Showing proportion of chemical ele-
ments in living things.
ORGANIC AND INORGANIC MATTER 9
so makes it less active. Nitrogen forms less than three
per cent of the body of plants and animals.
5. Calcium., sulphur, phosphorus, iron, and potassium are
the other important elements found in living things. None
of these elements forms as much as one per cent of the body
of plants or animals.
Chemical Compounds. — All these chemical elements com-
bine with each other to form definite substances called
chemical compounds, which we can see and handle. Oxy-
gen and nitrogen mixed together make up about ninety-
nine per cent of the atmosphere ; hydrogen and oxygen
unite to form water ; carbon, hydrogen, and oxygen unite
to form starch and sugar.
The union of oxygen with any other substance produces
heat or energy. This uniting is called oxidation. When
oxygen unites with carbon in our bodies, carbonic acid gas
(carbon dioxide) is formed and heat is produced. The
production of heat is one of the most important of the
changes that take place in living things.
Physical and Chemical Change. — If a solid piece of ice is
melted, it becomes liquid water. If the liquid water is
boiled, it becomes steam, vapor, or gas. If the steam is
condensed, it becomes water, which in turn may again be
frozen into ice. Any change in a substance which does
not alter the material of which it is composed is called a
physical change.
On the other hand, when oxygen unites with wood, the
wood burns, giving off heat and smoke, and asli remains.
But this ash cannot be united with heat and smoke to form
the original wood. Such a change as is seen in the burn-
ing of wood is called a chemical change.
Organic and Inorganic Matter. — It is customary to separate
chemical compounds which are made in living things from
those which are made outside the bodies of plants and
10 INTRODUCTION
animals. All matter such as wood, sugar, and meat,
which is made in living things, is called organic matter.
All matter like stones and water, which is made outside
of living things, is called inorganic.
Environment. — Plants and animals have accustomed
themselves to live in different parts of the world. . Their
behavior and habits under these varying conditions form
a most interesting part of the study of biology. The sur-
roundings of plants and animals, that is, the different con-
ditions, the air, water, climate, and soil in which they live,
are called their environment.
PRACTICAL BIOLOGY
PART I
ANIMAL BIOLOGY
CHAPTER I
THE GRASSHOPPER, A REPRESENTATIVE ANIMAL
1. Live Animals. — We all know that animals are alive,
just as men and plants are alive, and we naturally want
to know how they live, what parts of their bodies they
use in eating and breathing, and how they escape their
enemies. After we have learned about the lower animals,
we can compare them with
plants and with man, and it
will be interesting to learn
in what ways all living
things are alike.
When the study of
Biology begins with ani-
mals, all that is necessary
is to select an animal that can be conveniently found
and watched ; and then to try to learn where it lives,
what it does, how it produces its young, and what
relation it has to mankind. Material for study is easily
obtained wherever you happen to live, whether in the
city, the country town, or on the prairies. A nearby
park or vacant lot, the fields, the woods, or the plains,
u
Figure 6. — Female Grasshopper.
12
THE GRASSHOPPER
whichever you can reach most easily, will supply you
with a collection of insects, if you look carefully.
All insects will be found doing something. Some will
be flying from flower to flower, and you can watch to see
what they are doing; others will be busy on the leaves or
the stems, and a few minutes of observation will show you
whether they are friends or foes of the plant upon which
you find them. The most interesting way to study in-
sects is to watch them in their home life, but when this
cannot be done, they can be well studied in the laboratory.
Even in a large city a surprisingly large number of kinds
of insects can be collected by a class and brought alive
to the laboratory.
2. The Grasshopper. — The study of animals begins in
this book with the grasshopper. When during the late
summer we walk into the fields or along paths lined with
grass, we are often surprised at the number of grasshop-
pers which jump away as we approach. They are of va-
rious sizes and kinds. Some are small and without wings,
while others have small but well-formed wings. The
difference in the wings and in the shape of the body tells
us that there are various kinds of grasshoppers.
FIELD STUDY
To study living insects. Collect insects such as grasshoppers, crickets,
beetles, bees, wasps, flies, moths, butterflies, etc. Place some under
tumblers and complete your report as follows :
o
32
05
0
W
Mouth Parts
Where Found
H
a x
- 5
6
— f.
- C
~. Z.
Size oi
Wings
Size oi
Third
p
T3
CD
CD
3
House fly .
On food in the home
2
Small
Grasshopper
On grass in the field
6
4
Medium
Moth . .
On flowers in the park
6
4
Large
LIFE PROCESSES
13
3. Life Processes of the Grasshopper. — The young grass-
hopper must escape being eaten, must find food, must have
oxygen to breathe, must develop into an adult, and must
do its part in providing for another generation of grass-
hoppers. If the grasshopper fails in any one of the first
three of these necessities, it is unable to live, and conse-
quently the last and most important work, that of provid-
ing for the next generation, is not possible.
LABORATORY STUDY
Examine a live grasshopper. What are its means of locomotion ?
Compare its jump with its length. If in the same proportion, how far could
a man six feet tall jump ? How does the grasshopper obtain food ? What
protection from enemies does it gain from its color ? Notice the divi-
sion of the body into three regions ; head, thorax (tho'raks) which has
wings, and abdomen (ab-do'men). When the living grasshopper is held
between the thumb and finger, it " spits molasses." This is the partially
digested food from its crop.
4. Protection — When we look closely at the grass-
hopper, we find that it is provided with many character-
N>7U.'oU!.
J/bdomen
PntT.-rax
Figure 7. — Diagram.
Showing the main parts of the grasshopper.
istics which prevent its being caught and eaten. The
most important of these are its color and markings.
When a grasshopper jumps into the grass and remains
14
THE GRASSHOPPER
ibru
abrum
ndibU
mandible
ndiblf
mandible
'.;) nupo pharynx
quiet, its color so closely resembles the grass and the
sticks that many of its enemies overlook it. This is an
example of what is called protective coloration. The grass-
hopper is further protected by a pair of large eyes and by
simple ears which are located on the side of the body. By
means of these sense organs, it becomes aware of the
presence of enemies. The quickness of grasshoppers in
jumping also helps them to escape being eaten.
5. Food Getting. — The grasshopper has little difficulty
in finding its food. It eats leaves, and particularly the
leaves of grass. It does
not need a keen sense of
smell, as does the bee
which must search for
flowers. However, the
grasshopper has special
smelling organs located
in its antennas (£n-
ten'e), those long feelers
which grow out from
the head like soft horns.
The mouth parts
which cut and chew the
food consist of an upper
lip and two teeth (mandibles, man'di-b'ls). The teeth
are moved by powerful muscles which nearly fill the
head. These mandibles work from side to side, instead
of up and down as our teeth do. They are so effective
that sometimes when grasshoppers become numerous
they strip the grass of all its leaves, and even destroy
growing fields of grain.
6. Breathing. — All animals have some way of getting
oxygen to every portion of their bodies and of getting rid
of carbon dioxide. The grasshopper has no lungs such as
( in
maxilla
maxi ila
biu
a bium
Figure 8. — Mouth Parts of the
Grasshopper.
LIFE HISTORY
15
ours, nor does it breathe through its mouth. On each
side of the body are found a number of regularly arranged,
small openings, spiracles (spir'a-k'ls), which lead into *
branching tubes, traehece (tra/ke-e). These tubes carry
air to all parts of the body in order that the cells may be
able to take the oxygen from the air and give carbon
dioxide to it. The cell process in which oxygen is used
and carbon dioxide formed is called respiration. See
section 6, page 3.
7. Reproduction and Life History. — In the autumn, the
female grasshopper lays her eggs in a hole which she
makes in the ground.
The eggs remain in the
hole until the following
spring, when they hatch
into wingless grasshop-
pers. Their bodies are
covered by a firm skin,
called the exoskeleton,
which does not increase
in size as the grasshop-
pers grow, so this skin
must be shed to allow
room for growth.
Young grasshoppers, like young children, grow rapidly;
therefore the grasshoppers have to shed their skeleton often
and grow a new and larger one. The scientific term for this
shedding of the old skeleton and the growing of a new is
molt (molt). In the early spring and summer, the young
grasshopper molts again and again, each time growing
a little more like the adult grasshopper. This process
of growth takes three or four months. After the last
molt, it has wings and can fly, and so is a full-grown
grasshopper.
Figure 9.
a, Grasshopper laying Eggs ; b. Egg-
capsule ; c, Eggs.
16 THE GRASSHOPPER
LABORATORY STUDY
Work out the divisions of the body of the grasshopper : head, thorax,
and abdomen; the position of eyes. How are the antennae related to
the eyes ? How many distinct mouth parts are there ? The teeth or
jaws are the most useful in getting food. How do the jaws work ?
Sketch the head to show these parts with the mouth open.
Notice the attachment of the head to the thorax. The head fits into
the thorax. The loose anterior (front) portion of the thorax is the pro-
thorax (forward thorax). The first pair of legs is attached to it. Sketch
the prothorax to show it and its legs. The portion of the thorax back of
the prothorax is divided into two regions: the mesothorax (middle
thorax) and the metathorax (back thorax). The line between them is
not clear. Sketch these parts together with the legs and the wings. The
jumping legs are attached to the metathorax ; the outer wings to the
mesothorax ; the inner wings to the metathorax. The inner wings are
used in flying. The leg of the grasshopper consists of : (1) a small
section close to the body (the coxa) ; a long muscular part free from
spines (femur) ; a slender spiny part (tibia) ; and the three segments of
the foot (tarsus) . The last segment of the foot is furnished with hooks
which help the grasshopper in climbing, while the spines on the tibia pre-
vent slipping as the grasshopper jumps. The large muscles in the femur
of the last pair of legs, the spines on the tibia, and the hooks on the tarsus,
are special adaptations which help the grasshopper in various ways.
Notice the tapering abdomen, composed of ten segments (rings) or
parts of segments. Notice the depression and membrane in the first
segment. This is the auditory organ, but it is not a true ear. Sketch
the abdomen to show its features. The spiracles are located on the sides
of the abdomen.
8. Metamorphosis. — All animals which pass through a
marked change in external appearance as they become full
grown are said to undergo a metamorphosis (met-a-m6V-
fo-sis : Greek, meta, change; morphe, form). These
changes are more marked in such insects as the ants and
bees than in the grasshopper. For this reason we speak
of two forms of metamorphosis — complete and incomplete.
9. Incomplete Metamorphosis. — The newly hatched grass-
hopper, while very small, looks enough like a wingless
grasshopper to be identified as belonging to the grass-
COMPLETE METAMORPHOSIS
17
hopper family. Its form
does not change materi-
ally from the time it is
hatched until it is full
sized. Thus the grass-
hoppers become adult
by a growing process
termed incomplete meta-
morphosis, showing no
marked change in form
(Figure 10).
10. Complete Metamor-
phosis. — Certain other
insects, for example the
codling moth, hatch into
caterpillars from the
eggs that the female lays
in the apple. These
caterpillars are known
as larvae (dar've : Latin,
larva, mask). The larvae
of the codling moth are
the " worms in the apple." These larvae are not recog-
nized from their external appearance as young codling
— -
Figure 10. — Incomplete Metamor-
phosis of the Tree Cricket.
The tree cricket belongs to the same
family of insects as the grasshopper.
Figure 11. — Codling Moth Larva.
18
THE GRASSHOPPER
moths, yet that is what they are. As the larva eats a
great deal, it grows rapidly, molting again and again
until it becomes a
full-sfrown cater-
pillar. It then eats
its way out of the
apple where it has
been living its lar-
val life for several
weeks.
In some pro-
tected spot, under
the bark scales,
the full-grown
„, „ caterpillar then
Figure 12. — "The Worm in the Apple.' l
weaves a silken
covering (the cocoon, ko-koon/) about itself. In this
cocoon it molts again. When this last molt occurs, the
Figure 13. — Codling Moth Pupa.
caterpillar loses its legs and mouth parts, and is now
known as a pupa (pu'pa). The pupa does not eat, but
STRUCTURE
19
continues to breathe. Thus we speak of this stage in
the growth of the codling moth as the "resting stage"
This resting stage of the codling moth pupa l is very
short. Then a linal
molt takes place and the
fully formed codling
moth crawls from the
cocoon (Figures 11-14).
This series of changes
through which the cod-
ling moth passes from
egg into caterpillar, FlGURE 14._CoDLING MoTH.
then into pupa, and
finally into full-grown moth, is termed complete meta-
morphosis. Ants, bees, butterflies, beetles, and certain
other insects, all undergo complete metamorphosis.
There are a number of different terms used to describe
the larval stage of insects :
caterpillars are the larvae of butterflies and moths.
grubs are the larvae of beetles.
" wigglers ' ' are the larvae of mosquitoes.
maggots are the larvae of flies.
currant worms are caterpillars.
measuring worms are caterpillars.
11. Structure and Classification of the Grasshopper. — In
order to understand the grasshopper more fully it is
necessary to find its place in the classification of animals.
All animals that are known have been grouped into classes
for convenience in study. The grasshopper belongs
to the large class of animals called Insecta (In-sek'ta :
Latin, in, in; seco, cut).
The insects, as a class, have their bodies divided into
Larvae
1 Sometimes the codling moth passes into the pupa stage in the fall,
thus living through the winter in the " resting stage."
20
THE GRASSHOPPER
three regions — head, thorax, and abdomen. See Figure 7.
All have three pairs of legs, and most of them two pairs
of wings. . They breathe by means of air tubes (tracheae').
In becoming adult, all pass through metamorphosis, either
complete or incomplete. The
insect group is subdivided
into ten smaller groups or
orders.
The grasshopper belongs to
the order known as Orthop-
tera1 (6r-thop'ter-a : Greek,
orthos, straight; pteron, wing).
In the Orthoptera we find six
common families : grasshop-
jDers, crickets, katydids, cock-
roaches, walking sticks, and
praying mantids.
12. Economic Insects. — By
economic insects, we mean
those insects which, by their
activities, are either helpful
or harmful to man. If an insect has no economic impor-
tance, we mean that it does not harm us by eating things
useful to us, nor does it help us in any way.
The struggle to live is a problem for all animals, for
Figure 15. — Monarch Butterfly.
Showing how it carries pollen
from one clover blossom to
another.
1 grasshoppers, katydids, crickets
butterflies and motbs
beetles
bugs
bees, wasps, ichneumons, gall flies
flies and mosquitoes
dragon flies
May flies
stone flies
fleas
(straight wings)
(scaly wings)
(shield wings)
(half wings)
(membrane wings)
(two wings)
(teeth)
(short lived)
(net wings)
(wingless)
often called siphon-mouthed
Orthoptera
Lepidoptera
Coleoptera
Hemiptera
Hymenoptera
Diptera
Odonata
Ephemeridae
Plecoptera
Aptera
Siphonaptera
ECONOMIC INSECTS
21
man as well as for the grasshopper. All insects must eat,
and some eat the same things we wish to eat. Such in-
sects we call harmful. Others aid the growth of plants
by carrying the pollen dust from one flower to another ;
Figure 16. — Modern Spraying Outfit.
Used to destroy harmful insects.
others make honey. Such insects are useful. Certain
other insects, like the fly, carry the germs of disease.
These insects are particularly harmful, for they cause
sickness and death.
22 THE GRASSHOPPER
Certain beetles eat dead flesh or bury dead animals
by tunneling under them. Such insects are helpful.
We should study insects in order to find out which
are our friends and which our enemies. It would not do
to kill all kinds of insects, for in many cases we should
harm ourselves.
13. Economic Phases of the Grasshopper. — The grasshopper
eats the leaves of plants, and if there are many grass-
hoppers, they cause a serious loss of crops. The plague of
locusts mentioned in the Bible refers to grasshoppers. In
some of the Western States years ago the grasshoppers
came in great swarms year after year and destroyed
annually crops estimated to be worth 1200,000,000.
But ordinarily, owing to the activities of their natural
enemies, the number of grasshoppers does not become
alarming.
Among the natural enemies of these insects that do much
toward reducing their number are the birds. Some of
the greatest destroyers of grasshoppers are the quail, blue-
bird, sparrow hawk, butcher bird, crow, red-winged
blackbird, and kingbird. The crows, because of their
large size and great numbers, probably kill the most
grasshoppers.
Other members of the order of Orthoptera, that are
more or less harmful, are the cockroaches, the nuisances
of the pantry, and the crickets that eat the roots of plants.
There are also tree crickets which frequently lay their
eggs in raspberry cane and kill the cane above the place
where the egg is laid.
14. What has an Animal like the Grasshopper Accomplished
by Living? — (1) It has used plants as food to build a
complex body. (2) It has produced more grasshoppers.
(3) It has used some stored-up food which might have
been useful to cattle or sheep. (4) It has set free waste
QUESTIONS 23
carbon dioxide which can be used by green plants to assist
them in making food. (5) When it dies and decomposes,
its chemical substances are returned to the soil and air to
be used again by other living things.
QUESTIONS
What are the most important things that the grasshopper must do to
live ?
How is the grasshopper protected ? How does the grasshopper breathe?
How get its food ?
How does the grasshopper begin life ?
Define metamorphosis. How many kinds of metamorphosis are there?
Which kind does the grasshopper show ?
Is the grasshopper a friend or an enemy to man ? Why ?
*$0&*
CHAPTER II
OTHEE COMMON INSECTS
In the preceding chapter we studied the grasshopper, a
typical member of the Orthoptera. We shall now take up
several other orders of insects, with most of which we are
already familiar.
15. Hemiptera. — Another common order of insects is
the Hemiptera (he-mip'ter-a: Greek, hemi, half; pteron,
Figure 17. — Scale Insects on Fern.
wing). To this order belong such common insects as
the cicadas, plant lice, the woolly aphis, and the bane of
the orchard, the San Jose (san ho-sa') scale. Some of
these are very harmful. When the San Jose scale is
allowed to feed freely, whole orchards may be destroyed.
Plant lice injure apple, cherry, and peach trees, and the
24
CICADA
25
Figure 18. — Mealy Bug.
One of the scale insects.
cabbage plant. The several kinds of scale insects which
harm orchards may be killed by spraying the trees with a
solution of lime and sulphur.
16. Cicada. — One of the most interesting insects of the
Hemiptera is the seventeen year cicada (si-ka/da), com-
monly called the " seventeen
year locust." The name is
given to it because the
nymphs (nim'fs, the imma-
ture stage) remain in the
ground, actively feeding on
roots, for seventeen years.
There is another kind of
cicada that remains in the
ground for thirteen years.
Every thirteen or seven-
teen years, generally in the
month of May, the nymphs crawl out of the ground, climb
trees or fences, and molt into adult cicadas. The adult
females lay their eggs in tender shoots of trees, and this
causes the shoots to die. The young cicadas, after hatch-
ing in the shoot of the
tree, go into the ground
and begin their long
period of larval exist-
ence which lasts thirteen
or seventeen years.
These cicadas are usu-
ally found in limited
areas, but in these areas
Figure 19. -Cicada, Adult and Nymph. are very numerous.
The cicadas which we
hear every summer are another kind, whose nymph lives
in the ground for two years. As there are two broods
26
OTHER COMMON INSECTS
of this species that appear in alternate years, the number
does not seem to vary from year to year. The birds do
much towards destroying them. The kingbird, sparrow
hawk, butcher bird, and
great-crested flycatcher
are their most common
enemies.
17. Coleoptera. — The
Coleoptera (co-le-op'-
ter-a : Greek coleos,
shield ; pteron, wing)
are the beetles. The
first pair of wings is
horny and meets in a
The second pair of wings
The mouth parts are for
Figure 20. — May Beetle.
Note difference in first and second
pairs of wings.
straight line down the back,
consists of thin membranes,
biting. Among the harmful beetles are many wood
borers, the May beetles,
potato beetles, asparagus
beetles, and weevils.
Some of the beneficial
beetles are the ladybug,
which feeds on destruc-
tive and harmful insects,
and the carrion beetle,
that feeds on dead
animals.
The ladybugs are
decidedly beneficial.
Their larvae run over
leaves and feed on other
insects. Even as adults they continue this good work.
Hop growers appreciate the value of the ladybug larvae on
their vines, as the ladybugs destroy the harmful hop lice.
Figure 21. — Eggs of Ladybug.
LEPIDOPTERA
27
Through the investigations of the United States I)e-
partment of Agriculture a certain kind of ladybug
(Vedalia) was found in Australia, which is the natural
enemy of an insect pest (cottony cushion scale) that was
destroying the orange trees grown in California. This
scale is a plant insect which was imported into the I nited
States on young trees.
Being1 freed from their
natural enemies (Ve-
dalia) which were not
imported, they had in-
creased rapidly. The
prompt importation of
Vedalia put an end to
their increase, and tliey
are now of no great
economic importance.
The bird enemies of
the beetle are numerous.
Among the most impor-
tant are the ring-necked
pheasant recently intro-
duced, the rose-breasted
grosbeak, and the quail,
which feed particularly
on the potato beetles.
The English sparrow, cuckoo, and kingbird feed on the
weevils. Robins, blackbirds, and crows eat the white
grubs, the larval stage of the May beetles. The wood-
peckers destroy great numbers of borers by digging holes
in the trees where the borers are tunneling.
18. Lepidoptera. — The Lepidoptera (lep-i-dfy/ter-a :
Greek, lepidas, scaly ; pteron, wing) include the familiar
moths and butterflies. Some of the members of this order,
Figure 22.
Holes made by Wood-
peckers.
28
OTHER COMMON INSECTS
Figure 23.
-Redheaded Wood-
pecker.
such as the adult peach-tree
borer, look more like wasps
than like moths. There are
more harmful insects in the
Lepidoptera than in any other
order. Among the particularly
destructive members are the
insects which are commonly
called codling moths, gypsy
moths, brown tail moths, tent
caterpillars, cut-worms, army
worms, and canker worms.
But not all the Lepidoptera *
the most beautiful moths and
are harmful. Many of
butterflies develop from larvae
that do no particular harm. Their
natural enemies, such as birds and
ichneumons (see section 21, page
39), keep their numbers reduced.
Among the more strikingly colored
butterflies are the black swallow-
tail, the larvse of which feed on
celery, parsley, and carrots ; and
the monarch or milkweed butter-
fly-
LABORATORY STUDY
The adult monarch butterfly has the
body divided into head, thorax, and ab-
domen. The legs are smaller than in the
grasshopper, while the wings are larger.
The butterfly is, therefore, poorly adapted
for jumping, but better adapted for flying
than the grasshopper. Draw the entire animal. Draw wings and legs.
Gently rub the finger on the wing, and as the dust comes off, the wing
Figure 24. — Larva of
Mourning Cloak Moth.
Gradually transforming
into a pupa. The cast-off
skeletons of the larva
appear in the middle row.
1 The Chinese silkworm is a valuable member of this order.
LEPIDOPTERA
29
will look more like the wing of a fly or bee. The lines that run length-
wise of the wing are the veins. Draw the winu.
The mouth parts of the butterfly are united into a single long tube
which is the coiled tongue-like structure, called the proboscis (pro-bos' is).
Unroll it and see how its length compares with the length of the body.
The butterfly uses the proboscis to suck nectar from flowers.
Figure 25. — Transformation of Pupa of Mourning Cloak Butterfly
into Adult.
30
OTHER COMMON INSECTS
As the butterfly goes from flower to flower after nectar, its head brushes
against the parts of the flower that grow the pollen dust. The pollen is
thus carried from one flower to another,
and this helps the flower to grow better
seeds.
Enemies of the Lepidojotera. —
The numerous enemies of the
Lepidoptera prevent them from
becoming a scourge. Chief
among these enemies are the
ichneumons, members of the
order Hymenoptera (Figure
40). Ichneumon- (lk-nu'mon)
adults lay their eggs on the
bodies of many caterpillars.
When these eggs hatch into
Figure 26. — Cecropia Moth.
Larva, pupa, cocoon, and
adult.
Figure 27. — Young Tobacco Worm.
Bearing cocoons of parasite.
small larvae ichneumons, the larvse eat their way into the
body of the large caterpillar, where they live feeding upon
its body juices. These ichneumon larvse are called para-
Charles Robert Darwin (1809-1882). the celebrated English
naturalist, was the founder of the Darwinian theory of evolution.
After taking part in the scientific expedition of the Beagle around
the world, Darwin settled in 1842 in the secluded village of Down
in Kent, where he devoted himself to a life of study and scien-
tific research. In 1859 he published his chief work. "The Origin
of Species," which was translated into many languages and be-
came the subject of more discussion than any volume of the age.
A second great work, "The Descent of Man," appeared in 1871.
and Darwin continued to produce important scientific works
throughout his life.
LEPIDOPTERA
31
sites because they derive their food from the caterpillar.
The caterpillar which contains these ichneumon parasites
is called a host.
The ichneumon parasitic larva3 grow rapidly and before
the caterpillar dies they reach the stage at which they
turn into pupse. When they are ready to pupate, they eat
their way out of the body
3f the caterpillar and
spin a cocoon which in
some cases remains at-
tached to the body of the
3aterpillar (Figure 27).
These parasitic larvae so
veaken the caterpillar
:hat it dies. We shall
earn more of these ich-
leumons later.
Next to ichneumons,
she birds are probably
:lie most active enemies
>f the Lepidoptera.
Many birds live entirely
ipon caterpillars and we
ind birds that seek them as food in all stages of their
levelopment and growth. The eggs laid on the twigs
md trunks of trees are eaten by chickadees, nuthatches,
Drown creepers, and woodpeckers. The larva' are eaten
3y many birds, notably by cuckoos, bluebirds, wrens.
blackbirds, orioles, blue jays, crows, and house sparrows.
The cocoons and pupae are sought by the chickadees,
woodpeckers, nuthatches, and brown creepers. The adult
nsects are preyed upon by house sparrows, chipping
sparrows, and the whole group of flycatchers, including
:he kingbirds and phoebes.
Figure 28. — Larwe of a Leaf Miner.
At work in an elm leaf.
32
OTHER COMMON INSECTS
19. Codling Moth. —
The most destructive
of the lepidopterous
insects is the codling
moth, already men-
tioned as an example of
metamorphosis. The
larvre become adult in
April at about the time
the early apple trees
blossom. The eggs are
laid on the young apples
and the larvse begin to
eat the growing apple,
which, as a result, in
many cases drops to the
ground. In any event
the quality of the apple
is injured.
In most parts of our country, there are two distinct
broods of the codling moth, the life history of which has
only recently been clearly understood. The eggs of the
second brood are laid
generally in August
when the fruit is pretty
well grown. The
same damage is done as
to the early apples, but
as each mature female
lays a hundred or more
eggs and as the most
important apple crop is
the late one, the chief
damage is at this time. Figure 30. — A Geometrid Moth.
Figure 29. — Cedar Bird.
Feeding its young a flying insect. One
of our most beneficial birds.
CODLING MOTH
33
It was estimated that
in 1898 the injury done
by the codling moth to
the apple and pear in-
dustry in New York
State alone amounted to
$3,000,000. By apply-
ing a spray containing
some poison just after
the blossoms have fallen,
the codling moths may
be destroyed. The spray
should not be used while
the blossoms are fresh,
because then the help-
ful bees which visit them
are killed, and no harm
is done to the destructive codling moths that come later.1
Figure 31. — Protective Coloration.
Figure 32. — Yellow Swallowtail.
Gathering honey from lilacs.
FIELD, LABORATORY, OR
HOME STUDY OF MOTH S
AND BUTTERFLIES
These insects are easily
collected and are interesting
to study. From late in the
spring until October you can
find lame and pupa?. Some
of the leaves upon which the
larvae are feeding should be
collected. The larva1 should
be placed in jars provided with
soil and some leaves. Arrange
the cocoons and pupa? which
you find as suggested in tin-
following table.
1 The life history of the peach-tree borer and monarch butterfly may be
assigned in this connection.
34
OTHER COMMON INSECTS
Cocoon
Pupa
Spun with
silk only
Spun with
a leaf
Spun with
hair
Without
cocoon
Suspended
from one end
Suspended
from one loop
Parasit-
ized
Tent caterpillars spin cocoons and form small brown moths. Celery
"worms" hang in a loop and form a black, swallowtail butterfly which
feeds on the nectar of lilacs and the rhododendrons of city parks.
The black spiny caterpillars of the willows and elms hang free from the
knot of silk and form the mourning cloak butterfly.
Tomato "worms" burrow into the ground and form a large-bodied,
small-winged moth, a sphinx moth.
20. Hymenoptera — The Honeybee. — In contrast to the
Lepidoptera, which, as has been said, are probably the most
****»
6
Figure 33. —
a, Honey Bee Worker ; b, Queen ; c, Drone.
Twice natural size.
destructive order, we find the Hymenoptera (hy-men-op'-
ter-a: Greek, hymenos, membrane or thin skin; pteron,
wing) that are of the greatest value to man. This order
includes the bees, wasps, ants, ichneumons, and the like.
HYMENOPTERA — THE HONEYBEE
35
Figure 34. — 1 href.
Queen Cells.
Natural size.
The honeybee and the bumble bee are
the most important of the bees. The
honeybee is valuable for its honey and
wax, and as a distributor of the pollen
which is necessary for the growth of
new plants. The bumble bee is valuable
mainly as a distributor of pollen.
Honeybees afford a splendid example
of community life among insects. In
the wild state they live in trees and
caves. All wild honeybees in this
country have escaped from hives or
apiaries (bee farms).
In a honeybee colony there are three classes of bees, —
the perfect females or queens,
the males or drones, and the
imperfect females, or workers.
There are generally one queen,
a few hundred drones, and twen-
ty to fifty thousand workers.
The queen alone can lay
eggs. She can lay an unfer-
tilized egg which hatches into
a drone, or she can lay an egg
which is fertilized. This fer-
tilized egg hatches into a queen
or a worker, according to the
food and the size of the cell
which are provided by the
workers. Thus the decision
as to whether the young bee
shall be a queen or a worker
rests with the workers themselves. They also have t lie
power to supersede the queen, or to raise a new queen
Figure 35. — a, Honey Bee
Egg; b, Young Larva; c, Old
Larva ; d, Pupa.
Three times natural size.
36
OTHER COMMON INSECTS
in case of the sudden death of the old one. These powers
are rightly intrusted to the workers — the great majority.
The eggs are placed by the queen in cells, and, after
hatching, are fed by the young workers, called nurses.
The larva is fairly bathed in food. In a few days the
larva is full grown, and
then pupates. The
workers now cap over
the cell with wax, and
in about twenty-one days
the young bee cuts away
the cap and crawls out
— an adult provided with
four wings, mouth parts,
antennae, and the six legs
of the honeybee.
Workers are provided
with the sting which is a
weapon of both defense
and offense. The queen
has a small sting, and
the drones have none.
When bees sting large
animals, like men, horses,
and dogs, their sting is
pulled out and with it
parts of the internal or-
gans, thus causing the death of the bee. When bees sting
other insects, or even one another, their sting is not lost.
Sometimes swarms which have few bees and little honey
are attacked by bees from other colonies. It is a pitched
battle until the " robber bees " are beaten back, or the de-
fenders are themselves killed. The sting is used in these
battles.
Figure 36. — Honey Bees Clustering
at Swarming Time.
HYMENOPTERA — THE HONEYBEE
37
Bees are instinctively sanitary. If a large bumble bee
enters the hive, the bees kill the intruder and usually,
finding him too large to be taken out, embalm him by in-
jecting the sting repeatedly into his body. The result of
this operation is to make
the bumble bee harmless
to the colony. Some-
times they cover the
body of a small, dead
animal with a case made
of propolis (prop'6-lis),
a substance the bees
gather from certain
buds. This serves to
protect the colony from
the effects of the decom-
position of the body.
At irregular intervals
during the ea/ly spring
and summer, bees have
the peculiar habit of
swarming. Several rea-
sons for swarming are
given by bee-keepers,
but no one pretends to
be certain that he really
knows the cause. It is a sort of revolt of the bees against
their condition. Two of the commonest reasons given to
explain swarming are the lack of room for the growing
colony, and lack of food.
When bees swarm, they usually light on the limb of a
tree and form a dense cluster. Here they hang from
fifteen minutes to an hour before leaving for the woods.
In a few cases bees have remained in this "cluster" state
Figure 37. — Capturing a Swarm.
38
OTHER COMMON INSECTS
overnight, but usually they are lost unless they are col-
lected inside of half an hour. The swarm consists of a
large number of adult bees, workers and drones, and
usually a single queen.
Various devices against swarming have been invented,
but the most effective is to clip the wings of the queen
in order that she may be kept at home, because the other
Figure 38. — Model Apiary.
bees usually follow her. This is done after the queen has
taken her " wedding-flight." Her wings are clipped close
to the body, but only on one side. The bees that then
swarm soon come back and are easily controlled. While
the bees are still in the air, a clean, empty hive is placed
where the old one was. Beekeepers, during the swarm-
ing period, always have a number of empty hives in position
ready for the swarm to occupy.
The returning bees enter the new hive in search of the
queen. As they are rushing in, the queen with clipped
HYMENOPTERA — THE HONEYBEE
39
wings is released, and she, in turn, joins the procession
and enters with the others. Having found the queen and
plenty of room, the colony is usually content to remain.
Sometimes swarming becomes a mania with certain colonics,
and it is difficult to get them to settle down contentedly in
a hive and make honey.
Runaway swarms have
to be watched with great
patience. Bees that have
been raised for many bee
generations in man-made
hives sometimes leave
suddenly and seek out a
hollow tree in the forests.
The length of the bee's
life varies. The drones
are usually killed at the
end of their first season.
Queens live for five or
six or even ten years.
Workers live three or
four weeks in the working season and several months in
the fall or winter.
The honey and wax produced annually in the United
States are valued at 122,000,000.
21. Ichneumons. — Another interesting division of the
Hymenoptera are the ichneumons. We have already seen
(page 30) how they help to keep the Lepidoptera from be-
coming a scourge. They also furnish other interesting ex-
amples of parasitism. As an illustration Ave may use one
of the larger ones known as Tfialessa. With long, thread-
like drills this parasitic insect bores holes in trees, and lavs
an egg at the bottom of the hole. The egg is usually laid
near the burrow of one of the larger tree borers, the Tremex*
Figure 39. — Cutting Combs from
Box Hive.
40
OTHER COMMON INSECTS
The larva of the
Thalessa makes its way
along the burrow of the
Tremex borer and fas-
tens itself to the body of
the borer, where it feeds
upon the borer and thus
kills it. In time the
adult Thalessa emerges,
ready in turn to do its
part in laying eggs
which will destroy more
of these enemies of the
tree. But if the Thalessa
parasites kill the Tremex
borer before it has eaten
Figure 40. — Ichneumon Flies. ., ,-, ■, . , * n
its way through the hard
Laying eggs in a tree. , . n ,.
wood, then all die to-
gether, because the Thalessa cannot cut an opening for itself.
Figure 41. — Adult Horn-tailed Saw-fly.
Just after laying eggs in a tree. The larvae of this
insect do much damage to lumber.
DIPTERA
41
22. Ants. — The ants are insects which live in large
families. Each family has many workers, and a number
of queens and males. Certain kinds have in addition their
soldiers which have strong mouth parts (mandibles). The
soldiers do the fighting for the family. Some ants are
winged and others are wingless.
Many ants have the curious habit of protecting the plant
lice, because these lice give off a sweet fluid of which the
ants are fond. In some cases the ants carry the plant lice
from the wilted leaf to a fresh one, or confine them in the
ants' nest and bring them fresh leaves. When they wish
to feed on the sweet fluid, the ants quietly stroke the body
of the plant lice with their antennae.
23. Diptera. — The Diptera (dip'ter-a: Greek, dia, two;
pteron, wing) include such harmful insects as the mos-
quito, housefly, botfly, and
cheese skipper ; also the bene-
ficial bee fly, wasp fly, and
tachina fly.
The most important member
of this group is the mosquito.
The common mosquito lays its
eggs in the water in small clus-
ters which look like minute
rafts. These eggs hatch into
larvse, called " wigglers. " Any
stagnant pool or rainwater bar-
rel furnishes a favorable place for mosquitoes to breed.
In the United States there are three distinct kinds of
mosquitoes. (1) The common mosquito is known by the
technical name of Culex (kiVleks). It is not known that
the Culex carries in its body any disease germs harmful
to men, therefore it is regarded as harmless, although a
source of great annoyance to those who frequent the woods
Figure 42. — Fly.
42
OTHER COMMON INSECTS
a
I
-
- * '
' ■!,
It
if ft
\a>.
3;- -
Figure 43. — Eggs and Larwe of
CULEX.
The commonest mosquito.
or seashore during the
summer. (2) Anopheles
(a-nof7 e-lez) is the scien-
tific name of a second
kind of mosquito, which
is also generally distrib-
uted, but is not so
numerous as the Culex.
The Anopheles often
carries in its body the
germs that cause the
disease called malaria.
(3) Stegomyia (steg-o-mi'ya) is a mosquito common in the
southern part of the United States. It is the insect
which carries the germs of yellow fever from one person
to another.
It is fortunate that the mosqui-
toes have so many enemies. The
" wigglers " are preyed upon by the
larvas of the dragon flies, by small
fish, and by water beetles; while
the adults are eaten by nighthawks,
martins, bats, and dragon flies.
Certain diseases caused by plants
attack the adults and kill them in
great numbers. The number of
mosquitoes can be greatly reduced
by destrojdng their natural breeding
places in old rain barrels, watering
troughs, boxes that may hold water,
pails, eaves troughs, and sink holes.
The larger breeding places are
sluggish streams and swamps.
Draining these is the most effective
Figure 44. — a, Adult
Culex ; b, Adult
Anopheles.
SUMMARY 43
method of preventing mosquitoes from laying their eggs
in that locality. When this is not possible, the surface
of the water may be covered with kerosene, which kills
the larvce by preventing them from getting oxygen from
the air. Frequent applications of oil greatly reduce the
number of mosquitoes.
SUMMARY
The insects include a large number of animals, the
smallest of which can be seen only through a microscope,
while the largest, certain butterflies, measure nine inches
across their wings. S.ome insects are parasitic and lead
dependent lives. Insects feeding on plants which we
wish to eat are called harmful. Others, like the honey-
bees and silkworms, which make products that we use,
are beneficial. Insects such as ticks and lice, that injure
our domestic animals, are called harmful. Then there
are the beautifully colored moths and butterflies whose
larvre never become numerous enough to do much damage ;
we say that they are beneficial because we get pleasure
from their beauty.
The whole question of what is beneficial or harmful
depends on the relation of the insect to man. Insects
living on an uninhabited island could not be thus classi-
fied. In the earlier stages of our civilization, many insects
now regarded as harmful were not so classified, because
man had not learned to use the plants upon which they
fed. The important relation which insects bear to disease
has, in recent years, caused us to classify several insects
as harmful which were not so considered earlier.
Insects, like man, are constantly undergoing a struggle
to escape their enemies and to secure food and a place to
live. It is interesting in this biological study to try to
view ourselves in the same unprejudiced way in which
44 OTHER COMMON INSECTS
we study the lower animals ; it helps us better to under-
stand ourselves, and to go forth better equipped to wage
our contest and win our fight.
QUESTIONS
Explain the difference between beneficial and injurious insects.
Which are some of our most beneficial insects ? How do they help
us?
How did they help to save the orange industry of California ?
How do fruit growers spray their trees ? Why ?
What can you do to prevent harmful insects from spreading ?
KEFERENCES
Crary, Field Zoology, Chapter X.
Folsom, Entomology with Reference to Its Biological and Economic
Aspects.
Hegner, Introduction to Zoology, Chapter XII.
Hodge, Nature Study and Life, Chapter X.
Kellogg, Animals and Man, Chapter XV.
Osborne, Economic Zoology, Chapter XII.
Root, A. B. C. and X. Y. Z. of Bee Culture.
Smith, Our Insect Friends and Enemies.
CHAPTER III
THE SIMPLEST ANIMALS — PROTOZOA
24. Definitions. — In our study of the grasshopper and
its insect relatives we considered their behavior and life
processes. If we had studied the minute structure of any
of these insects, the grasshopper, for example, and had
used a microscope to aid us, we should have found that
every organ was made up of numerous small parts joined
together in a definite manner. These small parts are
called cells.
Any book on biology uses the word cell again and again.
The name was first used by Robert Hooke over two hun-
dred years ago, when, with his crude microscope, he
examined a piece of bark and found it to be made up of
little rooms which looked like the cells of the honey com I).
These spaces he named cells. When better microscopes
were made, the living parts of the cell were discovered,
and it was found that Hooke had seen only the walls of
dead cells.
All plants and animals are composed of cells. A cell
may exist alone, carrying on all the life processes itself,
or it may exist in connection with a great many other
cells, as in all large animals and plants. In every case
each cell is produced from another cell.
There are certain animals that are never more than one-
celled even when they are full grown. These animals are
called Protozoa (pro-to-zd'a: Greek, protos, first; zoon,
animal).
45
46 THE SIMPLEST ANIMALS — PROTOZOA
25. The Protozoan Cell. — The protozoan cell is a single
mass of living matter, called protoplasm. In a general way
it carries on the same life processes as the grasshopper; or
any other animal. When this living cell comes in con-
tact with heat, cold, electricity, chemicals, or other stimuli,
it moves, and we say that it is irritable. The term irrita-
bility, used with a scientific meaning, is defined as the power
of being aware of a stimulus. When this living cell is
brought into contact with cold, for example, it makes a
definite movement. It is aware of the cold stimulus.
The . living cell grows by using food. It takes in oxy-
gen from the water or from the air, according to where it
happens to live. It gives off waste substances. It can
grow or reproduce other cells of the same kind.
Many protozoan cells have no limiting wall between
the living substance and the water in which they live.
Yet the protoplasm and the water do not mix, though we
do not understand why. Other Protozoa living in the
ocean are surrounded by extremely thin skeletons of lime,
and when the animals die their skeletons sink to the bot-
tom and become massed in a sort of rock. The famous
chalk cliffs of England were formed in this way.
26. Habitat. — The habitat of any animal is the place
where it lives. The Protozoa are small, usually micro-
scopic, animals common in stagnant pools and in swamp
water. They are also common in salt water. In fact,
Protozoa are likely to be found in nearly all ponds of
water that contain food for them. Often, in the summer
time, our attention is called to the activities of Protozoa
when the water from lakes or reservoirs has a fishy taste.
This peculiar taste may be due either to animals or plants,
or to both. When it is due to animals, it is caused by a
disagreeable oil formed by a certain kind of Protozoa.
By far the greater number of Protozoa are harmless,
STRUCTURE OF AMCEBA
47
and many arte helpful to us in that they serve as food for
fishes. Others, however, may become parasitic in our
bodies, and thus cause such diseases as malaria, yellow
fever, or sleeping sickness.
27. Amoeba. — The name amoeba (a-me'ba) is given to
several different Protozoa, but all of them represent the
simplest form of life known to us. For this reason they
are always studied in biology. In order to describe cor-
rectly the structure of even so simple an animal as the
amoeba a few new words are necessary.
28. Structure of Amoeba. — It is difficult for inexperienced
students to see the living amceba through the microscope,
because the whole cell
has a faint, grayish ap-
pearance, and in a strong
light is transparent.
But if this grayish ap-
pearance of protoplasm
is once seen, it is always
remembered.
The living amoeba is
continually changing
shape and pushing out
from the surface of its
body blunt, finger-like
projections of the proto-
plasm called pseudopodia
(su-do-po'dl-a: Greek, pseudo, false; pod, root of pons.
foot), which give an irregular outline to the body (Figure
45). Sometimes the pseudopodia branch out, and there-
fore the scientific name Rhizopoda (ri-zop'o-da: Greek,
rhizos, root; pod, root of pous, foot) is the technical
name for all amoeba-like Protozoa.
The amoeba sends out a pseudopodium, and gradually
Figure 45. — Micro-photograph of an
Amceba.
48 THE SIMPLEST ANIMALS — PROTOZOA
the rest of the body flows, by a rolling movement, in the
same direction. This creeping-rolling motion of the
protoplasm enables the amoeba to move through the water.
When the pseudopodium comes in contact with a minute
plant upon which the amoeba feeds, the protoplasm of the
pseudopodium surrounds the plant and takes it into the
cell. The microscopic plant thus eaten by the amoeba is in-
closed, with a small amount of water, in a tiny globe called
the food vacuole (vak'u-ol). The food vacuole is to be
thought of as a stomach in which digestion can take place,
for the plant is digested in it. The nutritious parts are
absorbed into the proto-
plasm, the undigested
parts are cast from the
cell, and the food vacuole
disappears.
There is no well-
defined cell wall ; there-
Feelmg pseudopodium.
Ectoplasm
Endopldsm / \
£»
Nucleus ;
Walking pseudopodium
Figure 46. — Diagram of an Amceba. f ore the amoeba IS an
illustration of a living,
naked cell. Near the center of the cell is a spherical
mass of denser protoplasm called the nucleus. In many
amoebaB the nucleus is not easily seen except by means
of specially stained preparations. The rest of the proto-
plasm in the cell is called cytoplasm (si'to-plazm). This
does not appear the same in all parts of the amoeba. On
the outside, there is a thin, almost transparent layer,
called ectoplasm (ek'to-plazm : Greek, ecto, outside;
plasma, form). The larger part of the cytoplasm is filled
with numerous small granules and contains several
vacuoles. This inner mass of cytoplasm is called endo-
plasm (en'do-plazm: Greek, endo, within; plasma, form).
The vacuoles in the endoplasm may contain food, water,
or waste products. The food and water vacuoles are
REPRODUCTION AND ENCYSTMENT 49
temporary structures, but the vacuole which collects
the liquid waste is always present. When this vacuole
reaches full size, it suddenly contracts and throws the
waste into the water. This excretory vacuole is therefore
called the contractile vacuole.1
29. Respiration. — The amoeba respires. From the air
dissolved in the water, it obtains by diffusion the oxygen
necessary to its life, and it gives off carbon dioxide from
the cell.
30. Reproduction and Encystment. — The chief method of
reproduction in the amoeba is simple (Figure 47 J. The
living cell divides into two
equal parts, forming two new
cells. This process is known
as fission (fish'un : Latin, fissus,
cleft).
When the food or water be-
comes unsuited to supply the _ Am A □
rr J Figure 47. — Amceba Repro-
needs of the cell, in order to ducing by Fission.
live the amoeba often secretes
(makes for itself) a thick wall completely surrounding
the protoplasm. This process is termed encystment (en-
sist'ment: Greek, en, in ; kystis, bladder). After the wall
has been formed, the amoeba is able, for a long period, to
resist cold, the drying up of the pond, or the lack of food.
1 No suggestion can be made which will always enable the teacher to secure
amoebae. They are more frequently found in the slime and mud of Stagnant
water than anywhere else. Paramoecia and other infusoria can usually be
secured in abundance by placing a handful of hay or leaves in a jar and cov-
ering them with the ordinary water used in the laboratory. This is called a
protozoan culture, and should be started about four weeks before the material
is wanted for class study. The length of time that the culture should stand
can be lessened by adding a little beef-extract and by keeping the jar near a
radiator. Water sufficient to keep the hay or leaves covered must be added
from time to time. When a good culture of paramoecia is once secured, the
jar should be kept from year to year, simply adding water to the dried hay
left in the jar wheu infusoria are desired.
50
THE SIMPLEST ANIMALS — PROTOZOA
31. Paramecium. — One of the most common forms of
Protozoa is the slipper-shaped paramcecium (para-me'-
shi-um), which is more active than the amoeba. It is
abundant in stagnant water and in the hay infusions pre-
pared in the laboratory. (See Laboratory Suggestions.)
LABORATORY STUDY
There are certain kinds of Protozoa that are usually found in protozoan
cultures. The most abundant form is the paramoecium. Make repeated
examinations of drops of water from the protozoan culture, until you are
able to find the paramoecium. Notice its shape, rate of movement, be-
havior on meeting obstacles, and the like. Report on what you can
make out. Compare the paramcecium with any other protozoan you can
find, as to shape, rate of movement, size, color, etc. If available, ex-
amine slides which show the nucleus of a protozoan. Make sketches
that illustrate the above features.
32. Structure of Paramcecium. — The paramoecium, like
the amoeba, is a single cell, but it has both a large nucleus
and a small one. It has
0$&
Contractile..
Vacuole
-L
•Cilia
•Cuticle
Trichocysts
an endoplasm, an ecto-
plasm, and a cuticle
(ku'ti-kl), or cell wall.
Through the cuticle,
there extend great num-
bers of cilia (sil'i-a), or
threads of living proto-
plasm. The ectoplasm
contains many thread-
like darts known as
trichocysts (trlk'o-sists).
These can be discharged.
On one side is a fold or
depression (the gullet)
in which food is collected by the waving motion of the
cilia. Within the cell are found food and water vacuoles
Food
Vacuole
•Contractile
Vacuole
Figure 48. — Diagram of Paramcecium.
REPRODUCTION, RESPIRATION
51
as in the amoeba ; but there are two contractile vacuoles,
one at either end, and the food and water vacuoles are
more numerous than in amoeba.
33. Locomotion and Defense. — The animal moves by the
action of the cilia, the direction bein^ due to the angle at
which the cilia are held. It can
be observed that the animals
move backward and forward,
and that they also rotate on the
long axis. Paramoecia defend
themselves by discharging the
trichocysts. This discharge
occurs either as a result of cer-
tain strong artificial stimuli,
such as electric currents or
chemicals, or naturally because
of collision with certain other
Protozoa. If attacked by some
animal which feeds upon them,
they discharge the trichocysts in the region of the attack
(Figure 49).
34. Reproduction, Respiration. — Paramoecia reproduce by
fission, i.e., an animal divides, producing two; these
divide and produce two more. The process of fission
goes on indefinitely (Figure 50). Like
the amoeba these forms can encyst win mi
conditions of life become unfavorable.
They can then be blown about in dust.
As in amoeba?, the oxygen which is
necessary to respiration is obtained
from the water. Excretory waste is
cast from the body by the contractile
vacuoles, which force it through the ectoplasm, (iases
escape from the entire surface.
Figure 49. — Paramecium.
Being attacked by another
Protozoan that feeds upon
it. The trichocysts are dis-
charged, and they force
the foe away.
Figure 50. — Para
mcecium reproduc
ing by Fission.
52
THE SIMPLEST ANIMALS — PROTOZOA
■
&S
35. Economic Importance. — Paramoecia consume consid-
erable quantities of bacteria, but whether more harmful
than helpful ones cannot
be told. Therefore their
economic value is un-
certain.
36. Other Protozoa. —
If one examines stag-
nant water, a large num-
ber of other kinds of
Protozoa will be found.
The more common forms
are much like the para-
mcecium and have many
cilia on the body.
Several of these large,
ciliated Protozoa feed on the smaller Protozoa. Some of
the common forms are shown in Figures 51-53.
All of these various Protozoa can be grouped into classes,
Figure 51. — Vorticella.
m
i!S'.-.«.Ji\:-i.v.'
Figure 52. — One of the
foraminfera.
Figure 53. — Some Flagellate
Protozoa.
each with certain distinct characteristics. For instance, all
Protozoa that have pseudopodia are called Rhizopoda. In
PROTOZOA AND ALCOHOL
53
this group, the cells may be naked or may possess a haul
mineral covering ; a second group of Protozoa are pro-
•
vided with one or more long, wavering threads called
flagella (Ha-jel'la : Latin, flagellum, whip), and have the
name Flagellata ; the flagella are longer than cilia and
exhibit more complicated movement. A third class,
known as Infusoria (in-fu-s<Vri-a), includes most of the
common Protozoa found in protozoan cultures. Most of
this class are provided with cilia.
LABORATORY STUDY OF PROTOZOA
Take a drop of water from an infusion rich in Protozoa ; place on
a slide and examine with a 16 mm. or J objective. Answer the questions
suggested by the report.
NlMBER OF
How Many Kinds —
How Many Kind>
Have —
Kinds
Observed
are free
swimming ?
are attached
by threads?
have even
motion ':
have zigzag
motion ?
constant
form ':
varying
forma !
37. Protozoa and Alcohol. — Scientists have studied tin-
relation of alcohol to the life processes of Protozoa. Nor-
mally, such Protozoa as paramcecia divide a regular
number of times each day. When a small amount of
alcohol is placed in water containing paramcecia, the
normal rate of fission is diminished. Professor Wood-
ruff has shown by an extended and critical study that
alcohol tends to prevent paramcecia from dividing as
many times as they would under normal conditions.
This means that alcohol hinders the growth of paramcecia.
54 THE SIMPLEST ANIMALS — PROTOZOA
SUMMARY
Protozoa are the simplest group of animals. They are
found mostly in water, yet some are parasitic in higher
animals. They are small and usually consist of only one
cell. They reproduce mostly by fission. Some produce
in man and beast diseases, such as malaria and the sleeping
sickness of Africa. But the great majority of Protozoa
are not harmful.
QUESTIONS
Compare the body of a protozoan with the body of a grasshopper. In
what are they alike ? In what different ?
How do the amoeba and paramcecinm compare ?
Explain how the Protozoa eat, digest food, produce more Protozoa,
and protect themselves.
How do these vital processes compare with the similar vital processes
in the grasshopper ?
In what ways are Protozoa injurious to man ? Are they parasitic ?
REFERENCES
Galloway, First Course in Zoology, Chapter X.
Hegner, Introduction to Zoology, Chapters IV, V, VI.
Jordan and Kellogg, Animal Life, Chapters II, III.
Kellogg, Animals and Man, Chapter V.
Osborne, Economic Zoology, Chapter II.
CHAPTER IV
THE SIMPLER METAZOA
38. Metazoa. — The Protozoa just studied are single,
free, living cells, while the grasshopper is made up of
thousands of cells. The grasshopper is called a metazoan
(mSt-a-zo'an : Greek, meta, after ; zoon, animal) because
there are many cells in its body. The Protozoa and the
Metazoa are alike in that both take in food, breathe, give
off waste matter, and reproduce their kind.
There are a number of organisms concerning which
scientists disagree as to whether they are plants or animals.
In zoology, these forms
are known as Colonial
Protozoa or simple Meta-
zoa. We shall study two
of these (Gonium and
Vol vox) and then examine
the sponges, which all
scientists agree are Meta-
zoa.
39. Gonium. — Gonium
is an animal made up of
sixteen separate cells held
together by a mucilage-
like secretion of the cells.
Each cell works independently in getting food, breathing,
giving off waste, and in reproduction. The colony
moves by lashing the water with long protoplasmic
55
Figure 54. — Gonium.
56
THE SIMPLER METAZOA
i
/...'©"
IMS?
threads (flagella), two of which project from each cell.
The advantage in rate of movement resulting from the
union of cells is illustrated in rowing. Eight men in
a large rowing shell can go faster than one man in a single,
small shell. In reproduction, the sixteen cells fall apart,
and each one grows into a new colony.
40. Volvox. — Volvox is a colony of hundreds of tiny
green cells embedded in a hollow gelatinous sphere.
Each cell has two flagella. For a time all the cells are
alike and share equally in the
work of the colony. But in
reproduction only a few cells
take part. In the simplest
method, a few cells grow large
and escape into the hollow
sphere. There, they divide
and grow into new colonies.
Finally, the mother colony
breaks, and the daughter
colonies escape.
The more complex method is like the reproduction of
higher animals. Certain cells in the colony grow large
and escape into the hollow sphere. They are the egg
cells. Other cells of the colony enlarge and divide into
large numbers of slender, free-swimming cells called sperm
cells. The sperm cells escape into the hollow sphere and
swim about. One sperm enters an egg cell and unites
with it, forming a single cell, the fertilized egg cell, which
can develop a new colony.
41. Division of Labor. — In gonium, the cells are alike in
form and function, but in volvox, we find that a few cells
have been changed in form in order better to perform the
special work of reproduction. This is the first step in the
division of labor.
&
Figure 55. — Volvox.
SPONGES 57
This is well shown in the higher animals, where certain
cells are grouped together for a given work. The diges-
tive system contains cells which work to make solutions of
the food eaten. These solutions nourish the whole body,
not the cells of the digestive tract alone. Certain other
cells are modified in such a way for secreting and holding
lime that they form bones by which the whole body is
benefited.
Some cells are grouped to form muscles to be used in
securing food and in enabling animals to escape from
their enemies. Other cells are for the purpose of convey-
ing and interpreting impressions, so that the animal may
hear the approach of an enemy, or detect the presence of
food. It is largely the carrying out of this " division of
labor " that tells us the rank of an animal or a plant in
biological classification.
In the business world we know of division of labor.
Years ago the cobbler made all the parts of a shoe. In
our large shoe factories to-day we find no one man
making an entire shoe. One man runs the machine that
cuts the leather and does no other part of the work.
He may have been a cutter twenty years, and he works
rapidly and accurately. Another man runs the machine
which sews uppers to the soles. He, too, is a rapid and
skillful worker. Other men have their special lines of
work to do. In the end they produce more shoes and
better shoes than this same number of men could, if they
were all cobblers and each finished his product. So in
the world of business we find the same plan of division of
labor that we are studying in biology.
42. Sponges. — Sponges are simple metazoa. In them
we find division of labor carried out in a more complex
way than in gonium and volvox. Simple sponges have
a body in the form of a hollow cylinder. Water enters
58
THE SIMPLER METAZOA
through the sides of the body and passes out through a
hole in the top. A simple sponge, called Grantia, grows
in salt water attached to docks or other objects submerged
along the seashore. On examination, it will be observed
that grantia is less simple than volvox.
Figure 56. — Bath Sponge.
A skeleton.
43. Structure. — Grantia is composed of three layers of
cells which show division of labor. The inner layer is
called the endoderm (en'do-derm). It consists of cells
provided with flagella which, by their movement, produce
a current of water through the central cavity. The
water enters through the holes in the sides (inhalent
pores) and is forced out through the opening at the top
(exhalent pore). The water contains food particles
which the cells of the endoderm have the power to take
in and digest. The food solution is passed to the other
cells in the sponge body by the process of osmosis.
STRUCTURE
59
& it
Figure 57. — Diagram.
To show parts of sponge.
This is a physical process in which gases or liquids of
unequal densities, separated by a plant or animal mem-
brane, tend to mix and become alike, the liquids or gases
passing through the membrane.
Thus the food digested is
passed on and nourishes the
cells of the middle and outer
layers. The cells of the middle
region form spicules (spic'uls)
of lime (Figure 58) that pro-
ject through the other layers Figure 58.
and strengthen the whole body.
The outer layer or ectoderm (ek'to-derm) serves as a
protective layer and with the help of the spicules gives
definite shape to the body.
LABORATORY STUDY
The sponge which we ordinarily handle is simply the skeleton, and is
easily kept from year to year. Examine several kinds of sponge skele-
tons and compare their shape, size, and the nature of the skeleton. How
60
THE SIMPLER METAZOA
much water will the pores of the sponge hold ? Microscopic sections of
Grantia are necessary if you are to make out the inhalent pores, the
central cavity, and spicules.
44. Reproduction. — At certain times of the year the
sponge reproduces by means of two kinds of cells (eggs
and sperms) developed in the middle layer. A sponge
may develop both eggs and sperms, but usually develops
only one kind at a time. Cells from the middle layer
move in between cells of the endoderm
and grow large and round. These are
the eggs (female cells). Other cells
move into the endoderm layer and divide
into many small ciliated cells (the sperm
or male cells). The sperms are set free
and escape into the water of the central
cavity and out from the body of the
parent sponge. A sperm enters the
body of another sponge and when it
finds an egg, fuses with it, thus forming
the fertilized egg. The fertilized egg
then begins to grow, and after a definite
period breaks away from the parent,
moves about for a time, and then settles down, attaches
itself, and grows into a mature sponge. The immature
sponge has the power of locomotion, but the mature form
loses this power. Nevertheless the sponge is an animal.
Reproduction that comes about through the fusion of an
egg and a sperm is called sexual reproduction. The other
method of reproduction, called asexual reproduction, also
occurs among sponges. By this method, sponges form
little buds or branches which develop into new sponges.
45. Spongilla. — Spongilla (spunj-il'la) is a fresh-water
sponge. At the approach of cold weather, certain repro-
ductive bodies are formed, known as winter-cells, and
Figure 59. — Two
Stages in the
Development of
the Sponge.
RELATION TO OTHER ANIMALS 01
these escape from the sponge. They settle down to
the bottom of the pond or stream and remain dormant
until the approach of warm weather, when they grow into
new sponges. They have a thick protecting coat which
enables them to resist unfavorable conditions.
46. Economic Importance. — The spicules of the different
sponges form a large part of their so-called skeletons.
These spicules are, in some cases, composed of lime and
form the limy sponges. In others, they are of silica and
form the glass}?" sponges. The more important sponges
have a skeleton made up of a hornlike substance which is
flexible. This is the sponge of commerce.
Great quantities of sponges are gathered from the sea
by divers and by dredges. The living tissues arc
allowed to decay, and the skeletons are then washed and
dried. Some are bleached to form the white sponges.
The sponges of best quality come from the Mediterranean
Sea and the Red Sea.
Sometimes fresh-water sponges grow in the water mains
of cities and towns, causing the pipes to become clogged.
47. Relation to Other Animals. — No animal is known to
eat the sponge. Sponges themselves feed on minute
particles of food, which are carried in by the currents of
water produced by the cilia of the endoderm. Some marine
animals use the porous body of the sponge as a retreat.
Certain sponges live in close relationship to higher
forms of animals. One kind is always found growing on
the legs of crabs. The movement of the crab carries the
sponge to water richer in oxygen and food, and the crab
is hidden from its enemies by its sponge covering. Each
animal gains by this inter-relationship. Where two such
animals as the crab and sponge live in this way the rela-
tionship is known as symbiosis (sym-bi-o'sfe : Greek, syn,
with ; bios, life).
62 THE SIMPLER METAZOA
SUMMARY
The transition from simple Protozoa, through the Colo-
nial Protozoa, to the Metazoa is simple and direct. In
gonium and volvox, the beginning of division of labor is
noticed ; that is, one part of the body becomes dependent
on another part for certain definite things. For example,
one cell is devoted to securing food, while another produces
eggs or sperms. The sponges are simple Metazoa in which
the division of labor has taken the form of producing
three layers, — the ectoderm, or outer layer ; the endo-
derm, or inner layer; and a loosely formed middle layer.
Grantia is a simple sac-shaped sponge which reproduces
both sexually and asexually. The general manner of
development by the sexual process is essentially the same
in all the higher animals, including man. The bath
sponges are the only ones of economic importance.
QUESTIONS
What can the single-celled protozoan do ? Compare with the Colonial
Protozoa, gonium and volvox. Explain the meaning of division of labor
in an animal. In what respects do sponges differ ? Of what use are
they ? Why are not all sponges useful ?
REFERENCES
Hegner, Introduction to Zoology, Chapter VI.
Jordan and Kellogg, Animal Life, Chapter II.
Osborne, Economic Zoology, Chapter III.
CHAPTER V
OCELENTERATES. HYDRA-LIKE ANIMALS
48. Ccelenterates. — -The Coelenterates (se-len'te-rats
Greek, koilos, hollow ; enter on, intestine) are simple
metazoa, a little higher in development than the sponges.
In the group are hydras (hl'dras), hydroids (hi'droids),
jelly-fishes, sea-anemone
(a-nem'o-ne), sea-fans,
and corals.
49. Structure of Hydra.
— The hydra is an in-
teresting fresh water
animal about a quarter
of an inch in length.
Its body is shaped like
a little cylindrical bag
with only one opening,
the mouth, which is
surrounded by a few,
usually six, delicate,
thread-like arms called
tentacles (ten'ta-kls).
The body is composed
of three layers, the
outer layer, ectoderm ;
the middle layer, the
mesoglea (mes-o-gle'a : FlGURE 60. - m.crophotographs of
Greek, mesos, middle ; Hydra.
G3
64
CCELENTERATES
Figure 61. — Diagram of Body
of Hydra.
gloios, glutinous substance) ;
and the inner layer, endo-
derm.
Each layer does some par-
ticular work for which the
others are not fitted. For
example, the outer layer
contains cells which are
especially sensitive to
stimuli and many modified
muscle cells that enable the
animal to move about. The
inner layer contains cells
provided with flagella which
catch the food particles for
the inner cells to digest.
The muscular action of the
outer layer moves the entire
animal. The sensitive cells enable the animal to recog-
nize its prey. The food digested by the inner layer is
used by all the cells of the body. Thus we see an
advance in the division of labor over that shown in the
sponge. We shall observe a still greater increase in
division of labor as we
study higher animals.
Tentacles are hollow,
finger-like branches con-
nected with the body
cavity. They are pro-
vided with stinging cells
which help the hydra to
capture living water fleas,
and the like. These
stinging cells have darts
Figure 62. — Microphotograph of
Body Wall of Hydra.
REPRODUCTION
65
which are automatically discharged when the tentacles
come in contact with little animals. The darts stun the
prey and render escape impossible. The tentacles sur-
round the food and carry it to the mouth, which opens
directly into the food cavity. The action of the tentacles
in doing this work sug-
gests the idea that each
tentacle has some way
of realizing the efforts
Endoderm
Mesoglea
Ectoderm
Figure 63. — Diagram.
To explain cell layers in Figure 62.
of the others.
We should keep in
mind that in the meta-
zoan the united cells are
in connection with each
other through the cell
walls. This is true even if we are not able to trace the
connections with the microscope. In the higher animals
we shall find that connections between cells are made by
means of nerve cells. The development of a nervous
system only carries out division of labor to a greater
degree.
50. Respiration and Excretion. — By osmosis, oxygen is
absorbed from the water by the cells of the ectoderm.
The water that enters the mouth carries oxygen, and by
osmosis it is absorbed by the cells of the endoderm. At
the same time the carbon dioxide from the cells is thrown
off into the water.
51. Reproduction. — The hydra reproduces both sexually
and asexually. In sexual reproduction eggs and sperms
are produced by the ectoderm cells. The sperm cells
escape into the water and, like sperm cells of all other
animals, have the power of locomotion. The fusion of
the egg cell and a sperm cell starts growth which results
in the division of the egg cell into many other cells.
66
CCELENTERATES
Hydras also reproduce asexually by budding. The buds
soon separate from the parent and begin an independent
life. Like the developing sponge, the developing hydra
grows until it finally becomes a fully formed hydra.
LABORATORY STUDY
The living brown or green hydras can usually be found in the spring or
fall in most fresh water ponds. They are easily collected by gathering
the floating leaves and overhanging grass that is immersed in the water.
Place this collection in a glass jar in the laboratory. In a couple of days
the hydras will have moved from the grass to the sides of the jar. They
can be examined by a small magnifying glass in the jar or be transferred
to a watch glass and observed under the low power of the microscope.
Watch the hydra contract, when jarred or touched. Note that the tentacles
become very short. Try feeding with a small bit of raw meat. Make
out the transparent ectoderm and the darker endoderm. Are there any
buds ? What happens to the buds when the parents contract ?
52. Hydroids. — Hydroids are marine, hydra-like animals
which are united in groups forming a tree-like colony
(Figures 64-66). They are often mistaken for plants.
Figure 64. — Microphotograph
OF THE HYDROID ObELIA.
Figure 65. — Diagram of the
Hydroid Bougainvillea.
HYDROIDS
67
When the young hydroid first begins to grow, it looks
like the fresh water hydra (Figure 60).
As the hydroid grows, branches
form and on the end of each branch,
tentacles and a mouth appear.
Figure 66. — A Hy-
droid Colony that
Looks like a
Plant.
Figure 67. — A Hydroid Medusa.
Each branch is able to capture food and, after it takes
what it needs, the surplus is distributed to other parts.
This is easily brought
about, as a common
digestive cavity con-
nects all of the branches.
The hydroid is termed
a colony because all of
the branches are united
and help each other in
getting enough food for
all.
Some of the hydroids
form curious buds which
develop into medusce
(me-du'se). See Figure
^ ° Figure 68. — The Medusa Known as
bi. As soon as the Pelagia
68
CCELENTERATES
medusae are set free from the
hydroids, they swim about and
capture their own food. Each
medusa is provided with either
ovaries (o'va-riz), organs which
grow egg cells, or spermaries
(speYma-riz), organs which
grow sperm cells. When the
eggs and sperms mature, they
are discharged into the water.
A single sperm cell must fuse
with an egg cell before the
egg can begin to grow. This
union of these two cells is
called fertilization. The egg
grows into an embryo (em'-
bri-o), an immature stage dif-
fering in different animals,
and this gradually changes into
a small hydroid. The several
steps in this complicated series
of changes are illustrated in
Figure 69. The hydroids
and medusa3 show a form of
reproduction called alternation
of generations, that is, they
reproduce alternately sexually
and then asexually.
53. Sea-anemone. — Sea-anemo-
nes are animals allied to the
hydra. The interior of the
J <^k
Figure 69. — Pennaria Tiarella.
a. The hydroid colony ; b, one
of the female medusae, much
enlarged ; c, the egg of the
medusas beginning to segment
after it has been fertilized;
d, e, f, further segmentation
stages ; g, the blastula stage ;
h, the free swimming larva
(planula) ; i\ /, and k show the
gradual transformation of the
larva into a hydra-like colony.
Branches grow on the stage
shown in k until a colony like a results. This is the form that alterna-
tion of generations takes in this hydroid. (Arranged from a monograph
on Pennaria by C. W. Hargitt.)
CORAL
69
body cavity is subdivided by many partitions which in-
crease the digesting and absorbing surface. The sea-
anemone reproduces by eggs and sperms.
The resulting embryo is free at first, but later becomes
fixed to some object and develops into the sea-anemone.
There is no medusa stage.
54. Coral. — Geographies tell us of the many coral islands
and reefs built up by the coral animals. These animals
are coelenterates, most
of them closely allied
to the sea-anemone,
but the coral animal
secretes about the body
and along the parti-
tions calcareous (kal-
ka/ re-us, limy) skele-
tons which form the
stone-like masses of the
coral rock. The upper
portion of the coral
rocks is alive with
these coral animals.
The lower portion is made up of skeletons only. Suc-
ceeding generations build upon the work of their ancestors.
Corals reproduce much as trees grow branches, but at
certain periods eggs and sperms are produced as in the
sea-anemone. Then the embryo settles down, secretes its
own skeleton, and this is added to the work of other
corals.
Sea-fans and sea-plumes are coelenterates which have the
forms suggested by their names. A dried specimen of
either looks as if a branch had been dipped in a solution
and coated. The interior is of a horny substance. The
exterior is covered with a limy secretion.
Figure 70. — Some Common Corals.
70 CCELEN TERA TES
55. Economic Importance. — The corals alone of the
coelente rates are of economic importance ; they add to
many islands, protect others from being washed away, and
in some cases form entirely new islands.
SUMMARY
The hydra-like animals represent an advance in the
division of labor. The layers of their bodies are more
definite and do their work better than in the sponges.
Hydroids and the corals illustrate the formation of a
colony. In some of the colonies the division of labor is
more extensive than in others. The economic importance
of the corals has been, and continues to be, very great.
QUESTIONS
Explain fully how the hydra gets its food and how some of this food
finally nourishes the ectoderm cells. Compare the hydra and the hydroid.
In what are they alike ? In what are they different ? How does the
hydra reproduce ? How does the hydra get its oxygen ? Explain how
the coral animal has been able to form islands.
REFERENCES
Darwin, Structure and Distribution of Coral Reefs.
Hegner, Introduction to Zoology, Chapter VIII.
CHAPTER VI
THE STARFISH FAMILY. (Optional)
56. The Starfish Group. — This group of animals includes
the well-known starfish, the sea-urchins, sea-lilies, and
several soft-bodied forms such as the sea-cucumber. The
technical name for these different animals is echinoderm
(e-km'6-derm : Greek, echinus, spine ; derm, skin), mean-
ing spiny-skinned animals. Most of these animals have a
skeleton. Unlike that of
man it is on the outside
and is composed of cal-
careous plates. In some
forms, like the starfish,
the plates are embedded
in the skin, while in the
sea urchin the plates fit
edge to edge, forming a
shell. The plates support
many spines which project
out over the body giving
the spiny appearance char-
acteristic of the group.
Both the skeleton and soft parts are arranged in a radial
manner. The presence of spines and the radial arrange-
ment are two characters by means of which one can
recognize most of the echinoderms.
57. The Starfish. — Starfishes are found in salt water.
They are composed of a central region, called a disk, from
71
Figure 71. — Starfish.
72
THE STARFISH FAMILY
which extend five arms or rays. On the disk is a porous
circular plate. It is known as the madreporic plate
(mad-re-por'ik : Greek, mater, mother ; poros, soft). It
3
Tfu1
Figure 72. — Diagram of Body of Starfish.
c, liver ; v, stomach ; o mouth ; g , reproductive glands ; p, tube
feet ; s, stone canal.
serves to take water into a series of vessels by means of
which the animal moves and holds on to rocks and shells
at the sea bottom
58. Internal Structure. — If the upper portion of the
animal is removed carefully, the internal structure can
be examined. Each ray is nearly filled with masses of
yellowish green sub-
stance. This is a gland
which forms the diges-
tive fluids used in the
stomach. The wrinkled
mass in the region be-
neath the disk is the
stomach. The mouth is
just below the stomach
on the lower or oral side
of the body. At the
angles of the arms and
extending into each ray
are the reproductive
Pi
Figure 73. — Anatomy of the Starfish, glands, which vary in
LOCOMOTION 73
size at different ages and seasons. According to the sex
of the individual these glands produce either eggs or
sperms, which are discharged into the water.
LABORATORY STUDY
Dried specimens of starfish serve well for general study. These may
be compared with specimens which have been preserved in alcohol or
formalin. Work out the several parts such as disk, arms, madreporic
plate, spines, groove of the feet, and position and form of the mouth. If
skeletons of sea urchins are available, they are interesting for comparison.
59. Life History. — The eggs and sperms fuse outside
the body. In their development into adults they pass
through a series of striking changes. The young or
larval forms do not resemble the adults at all. This de-
velopment through a series of marked changes is as
striking as that seen in the insects and is likewise called
a metamorphosis.
60. Food Taking. — The starfish takes its food in an un-
usual manner. Most animals move the food to the mouth,
swallow it or engulf it, and digest it within the body
cavity. In the case of the starfish we find that the
stomach is projected through the mouth and made to
surround its food. In this position it digests and assimi-
lates the food and then withdraws its stomach through
the mouth and moves on slowly to some other place. A
common food of the starfish is the clam. The arms or
rays surround the clam, and the "hinge ligament" which
holds the shell together is tired out, thus causing the
protecting clam-shells to separate. The stomach is then
pushed out, enveloping the clam. The digestive fluid is
secreted and the dissolved clam is absorbed as food.
61. Locomotion, — The animal moves chiefly by means of
the tube-like feet found in the groove on the under surface
of the rays. These so-called feet make little sucking disks.
74
THE STARFISH FAMILY
Figure 74. — Purple Sea Urchin.
62. Respiration. — Oxy.
gen is taken from the
water and carbon dioxide
given off through little
thin-walled, gill-like
processes which cover
the upper surface of the
disk and arms. These
gill-like processes pro-
ject through holes in
the exoskeleton.
63= Other Echinoderms.
— The sea urchins are
thickly covered with spines and have tube feet which, in
many cases, may be greatly extended. When the spines are
removed, an exoskeleton is revealed, which readily shows the
radial arrangement characteristic of the echinoderm group.
64. Economic Importance of the Group. — Of echinoderms
the starfish alone has an eco-
nomic bearing. It is harmful.
Living as it does in the region
of the oyster and clam beds
and feeding almost exclusively
on them, the starfish annually
destroys thousands of dollars'
worth of clams and oysters.
By removing the seaweed where
the immature starfish gather and
by dragging the oyster and clam
beds great numbers of starfish
are destroyedc
In former times the fishermen
used to break starfish to pieces
on the side of the boat and throw Figure 75. — Sea Lily.
ECONOMIC IMPORTANCE 75
them back into the water. It is now known that by bo
doing they were but increasing the number of starfish, for
starfish have the power to re-grow the parts broken orf\
Each complete arm could reproduce an entire starfish.
This power to restore lost parts is known as regeneration
(re-jen-er-a'shun). Many of the lower animals have this
power to a marked degree, and all animals have it to
some degree.
SUMMARY
The starfish group of animals is known by the presence
of spines in the skin and a radial arrangement of the
organs. Their chief economic relation to man consists in
their great destructiveness to the oyster and clam beds.
QUESTIONS
Why are starfish so-called? How can they be distinguished from
other animals ? How do they move ? Where do they live ? On what
do they feed ? How do they breathe ?
REFERENCES
Brooks, The Oyster.
Osborne, Economic Zoology, Chapter VIII.
Poulton, All About the Oyster.
V
CHAPTER VII
THE WORM GROUP
65. The Worm Group. — Here are found several distinct
groups of animals that in advanced text-books of zoology
are treated separately. The word "worm " is an old term
which properly describes such animals as the earthworm,
sea worm, leech, tapeworm, flat worm, and a few others.
The word " worm ' cannot be correctly used for such
larvae of insects as the " apple tree worm " or " currant
worm."
The worm group is divided into two classes — those
whose body is composed of numerous segments (seg'ments)
or rings, such as the earthworm, the sea worm, and the
leech ; and those whose body is not segmented, such as
the tapeworm and flat worm. The first class comprises
the true worms, which are known as Annelida (a-nel'I-da).
The second class, the unsegmented worms, have no single
technical name, and are not believed by scientists to be
true worms. They comprise a number of worm-like ani-
mals which have hardly any features in common. Here
are found the fresh water planarians, the parasitic tape-
worms, liver flukes, and numerous round worms, of which
the hair worm is an example.
The planarian worm is one of the simplest of these un-
segmented worms. It is found under stones submerged
in stagnant water and in streams. It is frequently
brought into the laboratory and lives easily in aquaria.
76
®:
H
Mi
t*
&2»
Figure
76.-
-A
Pla
narian Worm.
TRICHINA 77
The liver fluke is a parasitic flat worm which each year
causes the death of many sheep by injuring their livers.1
Like some other parasitic animals the liver fluke requires
two hosts to complete its development. The hosts of the
fluke are the sheep and certain snails. The adult liver
flukes form eggs and sperms in the liver of the sheep.
The fertilized eggs par-
tially develop in the
sheep ; then as embryos
they pass down the bile
duct into the intestine
and then out of the
body.
The ciliated (sil'i-a-ted) larva then makes its way into
water or along dew-covered grass. If it comes in contact
with a water snail in the water or a land snail on the grass,
it enters the body of its second host, otherwise it dies.
Once inside the body of the snail it completes a compli-
cated development. By a bud-like process many young
flukes are formed which finally emerge from the snail and
make their way to the grass stems on which they encyst
themselves. If this grass is eaten by a sheep, the diges-
tive fluids set free the young fluke which goes up the bile
ducts to the liver, where it grows to maturity.
66. Trichina. — Another unsegmented worm that is of
economic importance is the Trichina (tri-klma), now gen-
erally called Trichinella (tri'ki-neTla). This worm lives
in the intestine of mammals and from the intestine mi-
grates into the muscles of its host. In the muscle it
becomes encysted and remains until the flesh is eaten by
some other mammal. When pork, infected with this
parasite and insufficiently cooked, is eaten by man the
1 The Animal Parasites of Sheep. Dr. Cooper Curtice. Bureau Animal
Industry, United States Department of Agriculture, 1890.
78
THE WORM GROUP
m
■ ■■
esMIh M?^ va a ■■■■
'•' . 1§ v i\*f '^^f if) ,
Figure 77. — Trichi-
NELLA.
cysts are dissolved by the digestive
fluids and the worms are freed.
These worms then develop eggs and
sperms which after uniting mature into
young worms and migrate through the
intestine into the muscles. The activity
of the worms at this stage causes a seri-
ous inflammation of the tissues and a
disease known as trichinosis (trik-in-
o'sis), which is often fatal. Hogs con-
tract trichinosis by eating refuse that
contains the encysted worms.
Government inspectors examine pork
which is to be exported or sold in large
quantities to see that it is free from these parasites. The
smaller sales of pork by local dealers are not inspected
and the only way to be sure of the harmlessness of the
meat is to cook it thoroughly.
Hair Worm. — The only importance that can be attached
to these worms is the myth about their origin. In almost
every school will be found
students who believe that
horse hairs placed in water
will develop into " hair
snakes." It would be a
pity if a student still be-
lieved this after a course in
biology.
Let us see how such a
belief can originate and
often be thought to be
proved. The hair snakes
live for a time in water
and often in the watering Figure 78. — A Common Tapeworm.
HAIR WORM 79
troughs where horse hairs are also found. Boys, and
men too, sometimes put horse hairs in water and then
after a few weeks examine the water and find these hair
snakes. They conclude, since they put in the hairs
and later found the "hair snakes," that the hairs grew
to form the snakes or small round worms. If they had
been as careful to look before any hairs were put iu, they
would have seen these "hair snakes ': swimming about.
A better test is to take a bottle of water, put in the
Figure 79. — Hair Worm in Body of Grasshopper.
hairs, and watch for developments. Such a test would
show that no hairs turn into hair snakes.
Hair snakes have a complete life history as clearly de-
fined as other worms. They lay eggs which fuse witli
sperms and form larvae. These larvse live as parasites in
the bodies of insects and fishes and when mature make
their way out of the bodies of their hosts. It would be
natural, then, to find them in pools where horses drink
and these parasitized fishes live, or in watering troughs
into which grasshoppers may have jumped, as they so
often do.
We know at present no way in which lifeless matter
can be made to live. A hair cannot become a worm and a
crooked stick cannot grow into a snake. New life comes
from the old. We sometimes read in the papers that
80 THE WORM GROUP
some one has produced life from chemicals, but it is not
believed at the present time to be possible.
67. The Earthworm is the simplest and best animal to
illustrate the annelid group of true worms.
When one examines a living earthworm, the head end
can be determined as the one which first moves forward.
Actually there is no head nor are there special sense
organs. The muscles in the front end are stronger and
the body rounder than in the back end. The back, or
dorsal (dor's'l) part, of the worm is exposed to the light
and is darker in color than the rest. This surface is
rounder than the opposite (under) one which is in con-
stant touch with the dirt when the worm is crawling.
The flat surface upon which the worm crawls is the ven-
tral (ven'tral) surface.
The body of the earthworm is made up of a number of
segments (rings) which are marked off by shallow grooves.
Some of the segments in the front end are larger than
those that make up the back end, but all are similar in
shape. The number of segments depends mostly upon
the age of the earthworm, and is from 60 to 150 in full-
grown worms.
68. Locomotion. — The earthworm crawls by means of
short, stiff bristles used as legs, the seta? (se'te : Latin,
seta, bristle), which are found in all of the segments
except the first two or three. These setce are arranged
in four rows, two in each row. To understand how the
setse are used in the locomotion of the earthworm it is
necessary to know that the body wall contains two mus-
cular layers. In the outer layer the muscles running
around the body are called circular muscles. The inner
layer, consisting of a number of bands running in the
direction of the length of the body, are called longitudi-
nal muscles. The contraction of the circular muscles
INTERNAL STRUCTURE 81
lengthens the body and the contraction of the longitudinal
muscles shortens it. The seta3 are connected with the
longitudinal muscles. By pointing the set;e backward
and bracing them against the ground, the worm can
push itself forward. By pointing the setae forward tin-
worm can instantly change the direction of its movement.
LABORATORY STUDY
One of the annelids should be studied with some care, as an illustration
of an invertebrate animal. How do you determine the anterior and
posterior ends ? Dorsal and ventral surfaces ? The number of segments '.'
Compare several worms. The back region of the worm shows the most
variation because new segments are being added. Where are the setae ?
How does the earthworm move ? Place it on a glass. The front region
of the body is most sensitive to touch. Test it.
69. Internal Structure of Earthworms. — This is shown
diagrammatically in Figure 80. The internal structure
consists of an outer tube,
the body wall, and an
inner tube, the digestive
tube. The space be-
tween the body wall and
f"iji yr
tdui wen
digestive tube is known FlGURE 8o.- Diagram.
as the body cavity or The organs of earthworm from the side.
coelome (se'liim : Greek,
koilos, hollow). Thin sheets of membrane pass from each
furrow between the segments to the digestive tube.
Beginning at the front end the digestive tube is given
certain names for each distinct region, as follows : the
mouth cavity; the pharynx (far'inks), with its thick
muscular walls ; the esophagus (e-sof'a-giis), thin- walled
and small ; the crop, a wide pouch ; the gizzard, where
food is ground; and the stomach-intestine, a large, thin-
walled tract extending through the last twro thirds of the
length of the worm.
82
THE WORM GROUP
The earthworm has an easily recognized nervous system
which is found beneath the digestive tube. It consists of a
continuous, minute, white thread with slight swellings in
each segment. From these swellings, which are called
ganglia (gan'gli-a: Greek, ganglion, swelling or tumor),
short branches extend to the digestive tube and other
organs. These branches are known as
nerves. Toward the front end the
nerve-thread parts and becomes double.
Each part passes around the front end
of the pharynx and enlarges to form
two ganglia, the largest found in the
earthworm. More nerves grow from
these two large ganglia than from any
of the others and so the term " brain '
is given to these two ganglia found in
the dorsal surface of the pharynx
(Figure 81).
The organs of the earthworm are supplied with blood
which is carried in a large dorsal blood vessel, a ventral
blood vessel, and numerous branches. The blood is
pumped by the contracting of the dorsal vessel and by the
five pairs of tubes which pass from the dorsal to the
ventral vessel around the esophagus. These five tubes
are named aortic (a-6r'tlk) arches.
Figure 81. — Earth-
worm.
Front end of nervous
system.
LABORATORY STUDY OF INTERNAL STRUCTURE
Work out the internal structure of the earthworm. In dissecting, cut
the skin along the dorsal surface, being careful to cut the many
membranes that hold the digestive tube in place. Work out the size and
position of the mouth cavity, pharynx, esophagus, crop, gizzard, and
stomach-intestine. The white reproductive organs are located beside the
esophagus. Locate the "brain," the ventral chain of ganglia. The
dorsal blood vessels and aortic arches should be located. Make a sketch
locating the organs in their respective segments.
EXCRETION 83
70. Life History. — In the starfish group the sexes are
distinct. The sexes in the annelids are distinct in some
forms and in others the same individuals have both
ovaries and spermaries. However, the sperms that unite
with eggs always come from another worm. During the
season when the ovaries and spermaries are forming eggs
and sperms, certain segments, usually six in number, be-
ginning with the twenty-eighth segment, and known as
the clitellum (kli-tel'liim), pour out a gelatinous secretion
which hardens into a collar-like sac around the worm.
This sac is worked forward and as it passes the openings
of the reproductive organs, eggs and the sperms from
another worm are pushed into it. The sac continues to
move forward and finally leaves the worm as a closed
capsule. This capsule contains eggs, sperms, and fluid
food. After the fusion of the eggs and sperms, the re-
suiting embryonic worms begin to feed upon the fluid
food in the capsule; later they feed upon each other
until but one may remain eventually to bore or eat
its way to the earth outside. From now on the food of
the young worm is the soil.
The earthworm is an example of an animal which has
both ovaries and spermaries.
71. Respiration. — Oxygen passes through the skin di-
rectly into the blood, which then carries the oxygen to the
various cells of the body. The outer surface must be
kept moist to permit the skin to act as a lung.
72. Excretion. — In each segment is found a pair of
organs known as nephridia (ne-fiid'i-a), which look like
little threads. These remove the liquid waste and carry
it to the outside of the body. It is believed that carbon
dioxide passes off through the skin, much as oxygen
passes in. This taking in and giving off of these gases
is accomplished by osmosis.
84
THE WORM GROUP
73. Food-taking. — The food of the earthworm is chiefly
the soil in which it burrows. By means of an upper lip,
which is a specialized anterior segment, and the muscular
walls of the pharynx, it takes the earth into its body and
the muscles of the digestive tube advance the food along
its course. The soluble and therefore digestible parts
are absorbed, and the remainder (the greater portion)
is passed along to the outside. Earth-
worms are not critical in the selection of
their food, although they are not entirely
without a sense of taste.
74. Economic Importance. — The value
of the earthworms to agriculture is too
great to be overestimated. In burrow-
ing their way through the soil they leave
passageways for water and air to enter,
thus assisting plants to grow. They
bring the fertile, swallowed soil to the
surface. When the large numbers of
the earthworms are considered, it is
obvious that they are the great natural
cultivators of the soil.
75 Other Annelids. — The sand worm or Nereis (ne're-is),
a marine or salt water form, is another segmented annelid.
It is more highly specialized than the earthworm, for it has
biting mouth parts, tentacles, and eyes. It is an active
swimmer at times. The development of the sand worm
exhibits metamorphosis, while the earthworm hatches di-
rectly into a worm without metamorphosis.
Figure 82. — Dero.
A common fresh-
water annelid.
SUMMARY
In the worm group are included the unsegmented worms,
such as tapeworms, liver flukes, and hair worms ; and the
segmented or true worms such as the earthworms, sea
SUMMARY s;>
worms, and leeches. All of these worms have more per-
fectly organized parts than the sponges and hydroids.
The body of the earthworm shows the first steps in tin-
formation of definite front, back, and ventral regions. The
digestive tube is also specialized into pharynx, esophagus,
crop, gizzard, and stomach-intestine ; and the name brain
may be given to a slightly enlarged portion of the anterior
end of the nerve cord. Small worms of various kinds are
numerous in stagnant water. Some live as parasites in
man and other animals, causing much suffering and loss
of life. The earthworm as a cultivator of the soil has been
of inestimable value to man.
QUESTIONS
"What kind of animals are called worms ? Is it proper to call " cur-
rant worms" worms ? Why not ? What are they ? How do you recog-
nize the anterior, posterior, dorsal, and ventral regions ? Compare the
grasshopper or some other insect with the worm. Explain how the earth-
worm moves ; makes its burrow. Compare the digestive tube with the
digestive sac of the hydra.
REFERENCES
Darwin, Earthworms and Vegetable Mould.
Jordan, Kellogg, and Heath, Animal Studies, Chapter VI.
Sedgwick and Wilson, General Biology.
CHAPTER VIII
CRUSTACEANS AND RELATED FOEMS
76. Crustaceans. — The Crustaceans (krus-ta/ shuns :
Latin, crusta, crust) are so-called because of their hard
outer covering. They belong in the same group of ani-
mals as the insects and are more highly developed than
the worms. The body consists of a limited number of
segments, each of which usually bears
a pair of jointed appendages. The
appendages are variously modified ;
some aid in swimming, others in
securing food, and others are used
in walking. The jointed appendage
is the characteristic expressed in
the technical name Arthropoda (iir-
throp'o-da : Greek, arthros, joint ;
pod, root of pous, foot) given to the
group to which all these animals
belong.
77. Crayfish. — As a typical crus-
tacean we have the common crayfish,
or " crab " as it is known away from
the seashore. The crayfish has nineteen pairs of append-
ages adapted to different kinds of work. It lives in fresh-
water ponds and streams where there is sufficient lime for
its use in building up its outside covering (exoskeleton).
The animal is divided into two regions, the head-thorax
region and the abdomen. The segments of the abdomen
86
Figure 83. — Crayfish
bearing Eggs.
LIFE HISTORY
87
are clearly defined, but tlio.se of the head-thorax are so
fused that they cannot be made out. The appendages of
Figure 84. — Crayfish.
the head-thorax region are the most important to the
animal. Certain of these are fin-like and by their constant
waving motion serve to carry food to the mouth. Others
are elongated and serve for walking. One pair, the
pinchers, are used for seizing
and holding.
The last abdominal segment
and the appendages next to the
last are broad and fin-like and
together form a tail fin (caudal
fin) for use in thrusting the
animal backward, when it is
alarmed.
78. Life History. — The sexes
are distinct. The males may be
distinguished from the females
by the larger tubular appendages
on the first and second segments
of the abdomen. The egr^s of the female are carried for
some time by the appendages of the abdomen, where they
pass through their early stages of development,. The
Figure 85. — Molted Exo-
skeleton of lobster.
88
CRUSTACEANS
young crayfish is unlike the adult in form, and approaches
maturity only after passing through many changes
(Figure 84).
79. Molting. — One of the interesting features in the
study of the crayfish is the shedding of the external skele-
ton. Being covered by a firm exoskeleton it is necessary
that this be removed occasionally, in order that the animal
may grow. Molting, in the case of the crayfish, is a
serious and dangerous operation, as it is followed by a
period during which the crayfish is without means of
offense or defense. The crayfish usually hides until a new
exoskeleton is partially formed. In the molting process
the covering of the eyes and part of the lining of the diges-
tive tract, as well as the whole exoskeleton, are shed.
The crayfish molts every year of its life and several times
during the first year (Figure 85).
LABORATORY STUDY
Place several crayfish in jars or aquaria and observe their behavior.
Fill out the following report :
DO THEY
Move the
Antenn.e?
DO THEY
Walk
Forward ?
Do THEY
Walk
Backward ?
Do they Use
Caudal Fin ?
Do THEY
Move Eyes ?
What Organs
Make a Cub-
rent in
Water ?
Laboratory study on the appendages. Examine more fully than in
the above and report the work of each pair of appendages. Compare one
of the abdominal appendages with those used in walking and feeling. What
is the work of the large pinchers ? How many fin-like appendages are
found in the mouth region ? Notice that one of the mouth appendages
has a flat part that extends in front of the gills. This part of the append-
age is called the gill scoop or bailer.
DIGESTIVE SYSTEM
SI)
80. Food and Food-getting. — The food of the crayfish is
both plant and animal, living and dead. One of the simple
water plants, Chara (ka/ra), furnishes the crayfish with
lime for its skeletons. Shells of snails and their own
shed skins also help to supply lime. Crayfish seize food
with their pinchers and move it towards the mouth. Small
food particles are also carried towards the mouth by cur-
rents of water produced by the mouth parts and the ab-
dominal appendages. Particles of food are torn loose by
the teeth or mandibles.
81. Digestive System. — The mouth is just back of the
teeth, and connects with the stomach by a short esophagus.
Figure 86. — Organs of Crayfish.
The stomach is divided into front and back parts. The
front part possesses a grinding structure known as the
gastric mill, which serves to shred and crush the food and
make it ready for digestion in the back part. The liver.
or digestive gland, pours a fluid into the stomach, which
prepares the food for absorption by the walls of the stom-
ach and intestines. The intestine begins at the back end
of the stomach and extends to the last segment.
90 CRUSTACEANS
82. Respiration. — Crayfish obtain oxygen from the water
by means of gills which are well covered by the overhanging
skeleton of the head-thorax region, but are really outside
of the body. Most of the gills are plume-like in shape
and are attached to the appendages, but some of them are
attached to the thorax. Water is made to circulate through
the gill chamber by means of the gill scoop or bailer. The
finely branched gill affords a large amount of surface for
the absorption of oxygen.
83. Circulatory System. — The crayfish has a well-devel-
oped heart from which extend several arteries- that carry
blood to the various parts of the body. The blood returns
to the heart through veins and through several irregular
ducts called sinuses (si'-nus-es). As the blood flows
through the body it loses oxygen and receives carbon
dioxide. Fresh oxygen is absorbed by means of the gills
which, at the same time, pass off carbon dioxide from the
blood into the water.
84. The Nervous System. — In the crayfish this is made up
of a brain, ventral nerve chain, and many nerves. The
eyes are borne on a pair of short movable stalks. The
special senses are well developed, and the sense of taste is
keener than that of most lower animals.
85. Excretion. — The organs for excretion of waste are
the green glands that are found at the base of the antennas.
Blood going to these glands loses some of the waste which
it has gained in its course through the body. The method
of purification of the blood in these glands is much the
same as in the kidneys of the higher animals.
86. Other Crustaceans. — Shrimps, lobsters, and crabs are
crustaceans of much economic importance, because of their
food value. The trade in these animals amounts to millions
of dollars each year. In order that these important food
animals may not become exterminated by careless and
ARACHNIDS
91
excessive fishing, the state and national governments have
attempted to control the numbers taken and have also
established hatcheries in which the eggs are hatched and
the young protected dur-
ing the earliest stages
of their development.
Crustaceans of less
economic importance
are the barnacles which
cling to rocks, wharves,
and steamships ; the
hermit crabs that live in
the shells of mollusks
(mol'lusks); and the smaller fresh-water crustaceans such
as the Cyclops (sl'klops), Daphnia (daf'ni-a), and Cypris
(si'pris) which are barely visible to the unaided eye.
Figure 87. — Soft-shell Crab.
Figure 88. — Pill
Bug.
Figure 89. — Cyclops.
87. Arachnids. — The spiders, scorpions (skor'pi-iins),
ticks, and mites are arthropods that are grouped together
under the name Arachnida (a-rak'ni-da : Greek, araehne*
spider). The spiders and scorpions have eight walking
appendages. The forward pinchers of the scorpions arc
mouth-parts, and not walking appendages. The harvest-
92
CRUSTACEANS
man (daddy-long-legs) is a harmless arachnid which does
good by destroying injurious insects. The spiders catch
insects either by pounc-
ing upon them or by
entangling them in their
webs. Scorpions sting
severely, but the wound,
although painful, is rarely
fatal. Some ticks and
mites are parasitic on
man and beast.
88. Myriapods. — An-
Figure 90. - Daddy-long-legs. Other group of arthro-
pods is the Myriapoda
(mir'i-a-po-da : Greek, myrias, many), a group which in-
cludes animals of many legs such as the centipedes
Figure 91. — Spider.
Figure. 92.
a. Thousand-legged
worm ; b, Centipede.
(sen'ti-pedz) and "thousand-legged worms." The
centipedes are provided with poison glands, and their bite
SUMMARY 93
is fatal to some of the smaller animals and painful to man.
The thousand-legged worms are harmless.
Note. Insects have been studied also in Chapters I and
II, but it should be remembered that they are arthropods.
SUMMARY
An animal belongs to the arthropods if it has more than
two pairs of appendages which have several joints in them.
They also have an external skeleton which is shed at
irregular intervals in order to allow the animal to increase
in size. The body of the crayfish shows that part of the
segments have fused to form the head-thorax region. The
members of this group vary much in size and habits.
Lobsters and crabs are valuable for food and for this
reason should not be caught when they are small.
QUESTIONS
What kind of animals belong to the crustaceans ? How can you dis-
tinguish one from a worm ? From a hydroid ? Explain why insects are
arthropods. Which groups of arthropods are beneficial ? Which are
harmful ? What do you mean when you say that an insect is beneficial
or harmful ?
REFERENCES
See Chapter II.
CHAPTER IX
THE MOLLUSKS
89. The Mollusks. — This group includes such animals as
clams, oysters, snails, slugs, squids (skwids), and octopi
(6k't5-pi). These forms differ from the crustaceans in
having a soft, unsegmented body and, in most cases, a
shell as their exoskeleton. The squids have a shell that
is internal, and the shell is absent in some of the snails.
90. Clams. — The fresh water clam is a convenient type
of mollusk to study. It is found in canals and in
many streams and lakes. This clam has two shells or
valves and, when moving naturally, the hinge is upper-
most, while the opened valves allow the foot to be ex-
tended into the mud.
The foot is a thick, mus-
cular mass, not at all
foot-like in appearance,
but it enables the clam
to move, although slowly
and at an uneven rate.
91. Structure. — The
structure of the fresh
water clam shows how
it has adapted itself to
its peculiar method of life. The shell is lined with a
membrane called the mantle. The mantle secretes the
shell-material and adds to its size year by year. At the
back, the edges of the mantle are united at three points,
94
Figure 93. — Clam Showing Foot.
Water enters through i.s., inhalent siphon,
and leaves the body of the clam
through e.s., exhalent siphon.
STRUCTURE
95
Showing mantle and muscles, a.a. an-
terior adductor muscle ; p. a, pos-
terior adductor muscle.
thus forming two openings known as siphons (si 'tons).
Through one of these siphons water enters, carrying food
and oxygen. Through the other the water passes out,
carrying the waste from
the body.
Between the mantle
and the body proper are
gills, which hang free in
the shell cavity. The
gills are filled with holes
through which the water Figure 94. — Right Shell of Clam
passes.
The foot is attached
directly to the body
proper and is the part of the clam hard to chew when it
is eaten. The foot and body form a solid mass that nearly
fills the space between the shells.
The two valves of the clam shell are held together by
means of strong muscles, attached to each shell. One of
these is located in front of the body and is known as the
anterior (front) adductor
(ad-diik'ter) muscle: the
second is just back of the
body and is the posterior
(back) adductor muscle.
When these two muscles
contract, the two valves
are held tightly together.
Before the live clam can
be examined these two
muscles have to be cut, as it closes its valves when
handled. When the clam is dead, these muscles relax and
the hinge forces the valves apart. It is not safe to eat
clams and oysters that have died in their shells.
Figure 95. — Digestive Tube of Clam
m, mouth ; s, stomach ; i.c, intestine.
96 MOLLUSKS
When the two adductor muscles are cut free from the
valves, a round or oval surface is seen which is marked off
from the rest of the interior of the shell. These areas
are called muscle scars (Figure 94).
When the empty clam shell is examined, it is found
that the hinge, sometimes called the hinge ligament, is
elastic. This is shown by compressing the two valves and
seeing how promptly they open when the pressure is taken
off. Where the two valves come in contact just beneath
the hinge ligament, a blunt projection of one shell fits into
a depression in the other. These are called the hinge
teeth.
LABORATORY STUDY
Live clams can be secured in the market during the school year. The
dissection of the clam is too difficult, but the arrangement of the organs
in the mantle cavity can be studied. The position of the adductor
muscles, foot, gills, palps, heart, etc., should be observed. Examine a
small portion of a gill under the microscope for cilia. A variety of
shells of clams should be studied in which hinge, muscle scars, and hinge
teeth are examined. Compare clam and snail shells.
92. Locomotion. — The movements of the fresh water
mollusks are extremely slow. In the clam the foot is
forced out of the shell by the blood, which flows into it
and causes the foot to be greatly enlarged. Muscles
attached to the shell and front of the foot contract and
pull the shell forward over the extended foot.
93. Food. — The food of the clam consists of microscopic
plants and animals that . are caught in a sticky fluid
(mucus) on the gills, as the water passes through them.
The food, together with the mucus, is moved into the
mouth by means of cilia. The mouth is simply an open-
ing into the body and the cilia are on triangular flaps or
lips (palps) on either side of the mouth. From the mouth
food passes into the digestive canal, where the nutritious
parts are absorbed (Figure 95).
- . "
1
■
N
CIRCULATION 97
94. Respiration. — The clam, like other aquatic animals,
gains its oxygen from the water and gives off carbon
dioxide. A close inspection of the mantle shows the pres-
ence of blood vessels which are more numerous than in
the gills. For this reason, the mantle is regarded as the
main organ of respiration, although the gills also assist.
95. Life History. — In clams the sexes are distinct. Kggs
formed in the ovaries of the female fuse with sperm cells
from the males taken in with the water through the
siphon. These sperm cells have reached
the water through the upper siphon.
Thousands of embryos form in the body
of the female and develop into larvse
in the outer gills which, thus become
greatly distended. Later the larvse
pass into the water through the upper FlGURoF96^MBRYO
1 * That attaches itself
The larvae of many fresh water clams to a fish.
have hooks on their shells and by means
of these they are able to cling to the gills or body of a
fish, where they live as parasites for several weeks. They
absorb food from their host and are carried from one place
to another and are thus scattered. After a few weeks they
leave the host and settle down to lead an independent
life.
96. Excretion. — The wastes of the body are absorbed
by the kidneys and passed out into the water through the
upper siphon.
97. Circulation is well developed.1 From the heart the
colorless blood is carried through arteries into smaller
tubes, and returns, through veins, back to the heart.
1 The three chambered heart lies in the dorsal region, near the hinge, in a
little soft-walled chamber, the pericardium (pe"r-i-c&r'di-um : Greek peri,
around; cardia, heart).
98
MOLLUSKS
98. The Nervous System is not so well developed as in
the crayfish. There are three groups of ganglia (nerve
cells). One located far back in the body near the posterior
adductor is called the visceral ganglion because it largely
regulates the activities of the viscera (vis'se-ra), the inter-
nal organs of the body. Another in the foot region is
called the pedal (pe'dal) ganglion, and regulates the
movements of the foot. A third located in the region of
the gullet (esophagus) is the cerebral ganglion, which
regulates the activities of the part near the mouth. All
of these are connected by nerves.
99. Digestive System. — The mouth, which is located
under the anterior adductor muscle, leads through the
short esophagus to the stomach. The intestine winds
through the foot region forming
a loop, finally ascending and
passing through the pericardium
and between the chambers of the
heart itself and opening into the
upper siphon (Figure 96).
100. Snails. — Snails having one valve are called uni-
valves as distinguished from clams, oysters, etc. which
are called bivalves because their shells are formed of two
valves. The greater number of snails
are marine (live in salt water), although
some live in fresh water and some on
land. Snails have a broad foot which
is used as a creeping disk. There is
a head region provided with eyes and
tentacles. The mouth of the snail is
provided with a rasping structure known
as the lingual ribbon (lin'gwal : Latin,
lingua, tongue) by means of which it
is able to cut and bore its way, even
Figure 97. — Snail.
Figure 98. — Tongue
of Snail.
(Magnified.)
SQUIDS, CUTTLE FISH, AND OCTOPl
99
through rocks. Land snails by osmosis get oxygen from
the air through the mantle, while water snails use gills
and take their oxygen from the water.
Figure 99. — Snail Shells.
In the garden slug the shell when present is thin and
affords small protection.
101. Squids, Cuttle Fish, and Octopi belong to the Cephalo-
pods (sefa-lo-pods : Greek, kephale, head ; pod, foot), the
highest division of the
mollusks. The nervous
system is highly devel-
oped. The eye of the
squid in particular is
complex and more like
the eye of vertebrates
than of any animal thus
far considered. The
mouth of cephalopods is
surrounded with ten-
tacles.
A common squid, Figure 100. — An Octopus.
100
MOLLUSKS
Sepia (se'pi-a), has ten arms or tentacles, two long and
eight short. It moves itself forward rapidly by shooting
out water from a siphon in the collar region. When
pursued, the squid ejects an ink-like fluid which clouds
the water, concealing it from its prey and facilitating its
escape.
Cuttle fishes are similar to squids, the marked differences
being in the shape of fins, the form of the eyes, and the
shape of the longer tentacles.
The octopi are the largest members of the group. They
have eight tentacles, which in some cases reach a length of
thirty feet. The stories about the size and
behavior of the octopi are often exaggerated.
102. Economic Importance of the Group. —
Clams, scallops, oysters, and snails are used
as food in all parts of the world. In this
country, oysters are gathered in great
abundance from Chesapeake Bay and other
bays along the Atlantic Coast.
The edible clams are of two kinds. The
round clam, Venus mercenaria (Ve'nus
mer-se-na/ri-a), is more generally used as
food, but the other kind, the soft-shelled
clam, Mya arenaria (Mi'a ar-en-a/ri-a), is
eaten extensively near the seashore. The
soft-shelled clam has a long siphon which
may be extended several inches beyond the
valves (Figure 101).
The scallop (skol'lup) is another mollusk
that is eaten near the shore more extensively
than elsewhere. This mollusk has but one adductor
muscle, which is the edible portion.
Clams and oysters are raised artificially and regularly
planted on natural feeding grounds. Care is taken to
Figure 101.
Soft-shell
Clam.
a, b, siphons; m,
mantle; s, shell;
/, foot.
Jean Louis Rudolphe Agassiz was born in Switzerland, in
1807, and died at Cambridge, Massachusetts, in 1873. He was
especially noted for his work in geology and ichthyology (the
science of fishes).
Agassiz came to the United States in 1846 on a scientific expe-
dition and took up his residence here, becoming Professor of
Zoology and Geology at Harvard, and Curator of the Museum of
Comparative Zoology at Cambridge. He explored the Lower
Amazon in 1865-66. In 1871-72 he accompanied the Hassler
expedition to the South Atlantic and Pacific.
Few have done more than Agassiz to popularize science, and
few teachers have trained so many young and rising naturalists.
ECONOMIC IMPORTANCE
101
have such natural enemies as the starfish removed, and, in
the case of oysters, brush and shells are added that they
-
':
\
w Vi? ■
ffmm
>
-
\
-
■
\ I • V. \
Figure 102. — Stages in Life History of Oyster.
may fasten to these rather than sink to the bottom, where
they become covered with mud. .
The culture of oysters and clams near the mouths of
rivers contaminated with sewage is unsanitary, and dis-
ease may be caused by eating such mollusks raw. This
Figure 103. — Barnacles and Clams Growing on Oysters.
102 MOLLUSKS
is one reason for the laws regulating the disposal of sewage,
and for government inspection of the feeding grounds.
SUMMARY
The parts of mollusks are not arranged in segments
like the earthworms or crustaceans. The usual presence
of a shell and mantle and the fact that the soft body is
not divided into segments helps to distinguish a mollusk
from any other animal. The microscopic food of the
clam is caught in the mucus and carried by cilia to the
mouth. The clams and oysters are valuable for food but
should not be eaten if taken from water contaminated by
disease germs. Mollusk beds should be protected from
such contamination.
QUESTIONS
What are some of the common mollusks ? Where do they live ?
How do they get their food ? What ones are used for food by man ?
REFERENCES
Brooks, The Oyster.
Cambridge Natural History, Vol. III.
Kellogg, The Shellfish Industries.
Linville and Kelly, Zoology.
CHAPTER X
PISHES
103. Vertebrates. — All of the animals thus far studied
are grouped together under the name of Invertebrate*.
because they have no backbone. We are now to study
the Vertebrates, animals with a backbone, such as fishes,
frogs, snakes, and birds.
The presence of a backbone in vertebrates is their most
conspicuous characteristic. The formation of the back-
bone is always preceded by the growth of an embryonic
Figure 104. — Skeleton of Fish.
Note backbone.
group of cells that do the work of a skeleton. This
embryonic group of cells forms a structure which is called
the notocliord (no'to-kord : Greek, notos, back; chorda,
cord). In all of the true vertebrates (such as fishes,
frogs, etc.), the notochord is gradually absorbed and the
backbone takes its place, but between the vertebrae it
remains as cushions. But in the fish-like animal railed
103
104
FISHES
Figure 105. — Perch.
Amphioxus (am-fi-oks'us), the notochord persists and
there is never a true backbone. The notochord is always
found above the food tube and below the spinal cord.
Another characteristic common to all vertebrates is
the presence of gill-slits. These are external openings on
Figure 106. — Sunfish or Pumpkin Seed.
VERTEBRATES 105
each side of the neck that in the fishes allow the water to
pass over the gills. Such structures are of use only to
aquatic animals, and yet all vertebrates have them at some
time in their development.
In most vertebrates the skeleton is composed of bone.
There are usually two pairs of appendages (legs, wings,
or fins) attached to the body at the shoulder and hip.
Here special bones join the limb to the body. The bones
in the shoulder are known as the pectoral (pek't6-ral)
Lr ^
1/ '
■ *^^
*
J#*-^>,
P^^^
HH|
%#
"V^^ **j •' \
s* *
K,m ;. -V
*"&:'-*> *T *5T
Figure 107. — Catfish, Bullhead, or Horned Pout.
girdle ; while those in the hip are termed the pelvic
(pel'vik) girdle. In the snakes, only traces of legs are
found (Figures 104, 139, and 158).
A further distinguishing feature of all vertebrates is
the well-developed nervous system, with its large brain.
The sense organs, eyes, ears, and the like, are also better
developed than in any of the invertebrates.
Oxygen is obtained by external or internal gills in most
aquatic animals and by lungs in all other vertebrates. In
many vertebrates the skin is an active agent in the inter-
106 FISHES
change of oxygen and carbon dioxide and particularly in
those animals which have a thin, moist skin like frogs.
104. Fishes. — The fishes are vertebrates, that is, they
have a notochord which as they develop gives place to a
vertebral column. There are four large divisions of fishes
(1) the lampreys (lam'priz) and relatives, (2) the sharks
and relatives, (3) the bony fishes, and (4) the small
1
'2~-T~~*i'mw
^Vj|S BwSjI&ftj^^
- ; -*2— ! - : A L
Figure 108. — Brock Trout.
group of fishes with lungs. The most important group
in numbers and economic importance is the bony fishes.
This group- includes the salmon (sam'un), trout, bass,
whitefish, pike, shad, menhaden (men-ha/d'n), cod, mack-
erel, herring, sardine, etc. Typical bony fishes are the
goldfish, perch, and sunfish (Figures 105-108).
105. External Parts of a Fish. — The external parts of a
fish show a well-marked head attached directly to the
trunk ; a trunk region, the largest part of the body ; and
a tail region which is sometimes as long as the trunk.
In a bony fish the mouth is at the front end of the
head. The jaw bones, bearing many small, needle-like
teeth, are not firmly attached to the skull. The side of
EXTERNAL PARTS
107
the head next to the trunk is protected by a piece of bone
that covers the gills (gill cover or operculum, 6-peV-
ku-liim), and the openings leading into the nostrils, which
do not connect with the mouth cavity.
The trunk bears a number of fins. Each fin is fur-
nished with several bony fin-rays covered by a thin fold
of skin. On the shoulder and
hip regions of the trunk, the
fins occur in pairs and are called
the pectoral and pelvic fins.
Several fins are found that are
not in pairs. These are the
median fins of the trunk.
The caudal or posterior re-
gion of the fish ends in a large
median fin. The tail region is
chiefly important in locomotion,
but the fins also help in balanc-
ing and steering.
Scales cover the trunk and tail, each one overlapping
like the shingles of a house. The skin is full of mucous
glands that keep the fish covered with slime. Both the
slime and the scales protect the fish (Figure 109).
Figure 109. — Scales of
Fishes. (Magnified.)
LABORATORY STUDY
Study living fish such as goldfish or perch. Place one or two in an
aquarium and observe their behavior. Fill out the report below.
Number
Number of
Paired
Fins
Number of
Unpaikkd
Fins
Which \i:k I -i D i"
I><> the
of Fins
Advance ?
Stop ?
Balance f
\'.\ bsMovi !
108 FISHES
Note the shape and relative position of the head, trunk, and tail region.
The gills are covered by a bony shield, the operculum. What is its size
and how attached ? Where are the eyes located ? Do they move ? Can
the eyes be closed ? How is the body covered ? Of what use is this
covering to the fish ?
106. Respiration. — Water is taken in through the mouth
and passes out through two openings, one on each side
of the neck. In each opening four or five gills are found.
The gills are made up of numerous, small, very short,
fleshy threads or filaments. Into each filament a blood
vessel penetrates and here the blood throws off carbon
dioxide and takes oxygen from the water by osmosis just
as the blood of the crayfish does. The thin-walled gill-
filaments are adapted to respiration in the water. The
water is drawn into the mouth and forced out over the
gills, in much the same way as water is pumped from a
well. When a fish opens its mouth, the water rushes in.
As the mouth is closed, the floor of the mouth and throat
is raised slightly, pushing the water against the side of
the neck and through the gill opening. The mouth is
thus emptied of water so that when it is opened again
more water flows in.
107. Food Taking. — Fishes eat insects, worms, crayfish,
snails, and other fish. The teeth of fish serve to seize, tear,
and hold food. None of the fish have teeth which are
adapted to crushing or chewing the food, as is the case
among the higher vertebrates, like the dog, horse, and
man.
Fishes which eat minute animals and plants have many
sharp pointed projections on the inside of the gill arches
which act as strainers and gather quantities of this small
food as the water passes over the gills. These projections
are called gill-rakers. Their development seems to vary
in proportion as they are needed for service. Fishes that
feed on crayfish and on small fish have no use for gill
REPRODUCTION 109
rakers or strainers and accordingly their gill rakers are
undeveloped.
108. Special Senses. — The eye is well developed. It is
globular and projecting, and is believed to be near-sighted.
The organs of smell are usually located in the nasal cavity.
In the bull-head, they are found in the feelers, on the head,
and even in the skin of the tail. The ear is under the skin,
and there is no external opening. As water conducts
sound vibrations more readily than air, no device for
gathering sound waves is necessary.
109. Circulation. — The blood of fishes is carried in well-
defined blood vessels and a heart of two chambers. The
blood is sent from the heart to the gills, where it is
purified of carbon dioxide and receives oxygen. It is then
carried by means of arteries to other parts of the body,
where the oxygen in turn is given up and carbon dioxide
is received. The blood from the gills and other parts of
the body is returned to the heart through veins. Because
the blood of fishes is at a lower temperature than the blood
of man, they are called cold-blooded animals.
110. Reproduction. — The sexes of fish are distinct. At
certain seasons many fish migrate upstream to lay their
eggs (to "spawn"). Eggs are laid in large numbers by
the females, and in the same locality sperm cells are dis-
charged into the water by the males. The sperms unite
with the eggs. The fertilized eggs hatch after thirty or
forty days, or longer, depending on the kind of fish and
the temperature of the water. The yolk of the eggs is
attached to the young fishes 'for many days after they arc
able to swim, and they need no other food than that sup-
plied by this yolk (Figure 111).
The spawning habits of fish must be understood thor-
oughly if they are to be raised artificially, as is done in the
many fish hatcheries. Most states have scientific game
110 FISHES
laws which protect the fish during their egg-laying period
when they are easily caught and when the destruction of
even a few fish means the loss of thousands of eggs.
Spawning habits vary greatly. Some fish, like the sal-
mon, make long journe}rs from the sea to 4;he head waters
of rivers and streams to deposit their eggs. The Colum-
bia River is famous for the number of salmon which spawn
there. Other fish, like shad, go up a river only a short
distance to lay their eggs. Many shad, for instance, go
Figure 110. — Eggs of Land-locked Salmon.
up the Hudson River in New York state. In the case of
herring, the eggs are laid in the sea and float on the sur-
face. Eels go down from the rivers and streams to the
sea to lay their eggs, the young eels, when small, migrat-
ing up the river. Millions of small eels no larger than
needles are found in the Hudson at certain seasons.
111. Fish Hatcheries. — In the natural state, many eggs
are laid that never hatch because the sperm cells do not
come in contact with them, and of the fishes that are
hatched only a small proportion reach maturity. As it is
a matter of great economic importance that fishes be saved
from extermination and their numbers largely increased,
FISH HATCHERIES
111
the governments of the world have established hatcheries
where fish are raised in great numbers.
In these hatcheries the eggs are taken from the female
and placed in a jar, and the mass of minute sperm cells or
"milt" is taken from the male and poured over the eggs,
Figure 111. — Young Fish Showing Yolk Sac.
so that practically all the latter hatch. Then by^ giving the
developing eggs protection, and the young fish sufficient
and proper food, nearly all of these eggs develop into
active fish and the great loss that comes to the fish develop-
ing in their natural environment is prevented. When
they are able to take care of themselves, these fry, as the
young hatchery fish are called, are taken to natural feed-
ing grounds. In New York state and most other states
pKppg
Figure 112. — Young Fish Fry.
there are state hatcheries where such fish as shad, pike,
lake trout, salmon, brook trout, and others are raised by
millions.
The fish that are most useful as food are taken by hooks,
nets, and seines, under certain restrictions. Those like
brook trout which are caught as much for sport as for food
can be taken only by a hook and line and in certain seasons;
112 FISHES
the season of the year depending upon the time of spawn-
ing. The brook trout spawns in August and September,
while the rainbow trout does not spawn until February or
March.
112. Care of Young. — Some fish, like the sticklebacks,
build nests of sticks and leaves in which the eggs are
placed and guarded. Bass and sunfish make a circular
depression several feet in diameter near the shore and lay
their eggs on these so-called ubeds." These beds are
guarded zealously by the males, who drive off or carry
away crayfish and small fish which feed upon such eggs.
In former times men sought for these " beds " and by
dropping a baited hook caught the bass while defending
their eggs. Fortunately this practice is now illegal.
Generally, adult fish pay no attention to their young and
in many cases they devour young of their own kind as
quickly as fish of other sorts.
SUMMARY
The term vertebrate is given to all animals that have a
backbone. All have gill slits, either while young or as
adults. Fish have scales and breathe by means of gills.
Their eggs are usually laid in the water and receive no
care from the parents. A few fish prepare a crude nest
which they guard.
QUESTIONS
What are some of the structures that all chordates have ?
Why is the word vertebrate used ?
What are the common fishes near your home ?
What ones are sought for food ?
What is being done to keep up the supply of fish in your state ?
What do fish eat ?
REFERENCES
Fish Manuals of the U. S. Commission of Fish and Fisheries.
Jordan, Fishes.
Jordan and Evermann, American Food and Game Fishes.
CHAPTER XI
AMPHIBIANS
113. Amphibians. — Frogs and toads are the best known
animals of this group ; but here belong also the Sala-
manders (sttl'a-man-ders), frequently miscalled lizards (see
page 131). The Am-
phibians (am-fiL/i-ans :
Greek, amphi, double ;
bios, life) are all small,
the largest one found
in America being a
salamander (Crypto-
branchus),
rarely more
feet long.
Amphibian is used to
explain the habit which
frogs, toads, and certain
salamanders have of spending their larval (tadpole stage)
life in the water and their adult life on land, or partly on
land and partly in the water.
which is
than two
This term
Figure 113.
— Some Common Sala-
manders.
LABORATORY STUDY
Place one or two frogs or toads in a small jar or box and observe the
points mentioned in the report below.
DO THEY
Wink?
Can tiiky
Protect
their Eyes ?
How Do they
I . i;t An: ':
Can tiiky
W \ ik F Hop ?
How Do
l 1 1 B Y 8w] M J
HOW Do THOT
Uatoh \ Y\.\ :•
113
114
AMPHIBIANS
Figure 114. — Common Frog.
114. Frogs. — There are several kinds of frogs, one of
which, the leopard frog, is found generally distributed
throughout the United
States. It can be recog-
nized by the presence,
on the dorsal surface, of
many brownish or green-
ish spots, edged with
white, which help the
frog to escape the notice
of his enemies as he
squats among the water
weeds. These colors
form rather definite bands on the hind legs, though there
is much variation. The general form of the body, the
shape of the head, and the long hind legs adapted for
jumping are much the same in all frogs.
LABORATORY STUDY
Compare the general shape of fish and frog. How do the colors
differ ? Show how the legs and feet are adapted to the way the frog
lives. Is the frog sensitive to touch in various parts of the body ?
Examine the eyes. Open the mouth and see that the frog can draw in
its eyes. The ear membrane is on the side of the head back of the eyes.
Pass a probe through the ear membrane of a dead frog and see where it
comes out in the mouth. This is the opening of the Eustachian tube.
How far can the living frog see ? Notice the method of breathing. See
the throat move up and down. Hold the frog under the water and
gently rub its sides. It will usually croak. Thus we can prove that the
frog is able to make the air travel from his lungs to his mouth and back
again while under water.
115. Habitat. — Frogs are seldom found far from some
pond or stream and they are usually seen on the bank.
When disturbed, they jump into the water, swim to the
bottom, stir up the mud, and quietly come to rest a
short distance from the place where they entered. As
INTERNAL STRUCTURE 115
the nights in the fall grow cool, frogs make ready to
spend the winter in a state of inactivity. During the
warmer part of the day, they may be seen sunning them-
selves on a bank, but as soon as ice forms on the water
they remain on the bottom or become buried in the mud.
The lungs are emptied of air, the heart beats decrease, and
all of the usual living processes take place more slowly.
This habit of passing the winter in a state of inactivity
is known as hibernation (hl-ber-na/shiin). All of the
amphibia, reptiles (Chapter XII, page 129), and several of
the mammals hibernate during the winter.
116. Food. — Frogs are greedy creatures and will eat
almost any animal small enough to be swallowed, such as
insects, worms, snails, tadpoles, and small frogs. These
are caught alive and when in motion.
117. Enemies. — As the frog's hind legs are considered
a delicacy, man is the worst enemy of the frog. Next
come the snakes, birds, and fish. The leech kills frogs by
sucking their blood. Fish eat many of the tadpoles, and
strange to say, some water beetles eat tadpoles also.
118. Respiration. — Both the skin and a pair of lungs
serve to purify the blood of the frog. The air is forced
into the lungs by the contraction of muscles in the floor
of the mouth. Experiments have been made which show
that the frog can get enough oxygen even if the lungs
are missing. In this respect frogs resemble worms, which
use the skin as the only organ of respiration.
119. Internal Structure. — A study of the parts of the frog
or toad should be made for two reasons: (1) To understand
the relative positions of the internal organs of a typical
vertebrate; (2) to help explain the several organs of
man which are discussed in the second part of this book.
Digestive Organs. — The mouth is large. Short lips
cover the short teeth in the edge of the upper jaw. The
116
AMPHIBIANS
tongue has two fleshy horns at the back end and is
attached by the front end to the floor of the mouth
(Figure 115). The frog can throw its sticky tongue over
the tip of the lower jaw and use the forked end to catch
insects which are then carried into the back of the mouth.
Two groups of little curved teeth in the roof of the
mouth aid in preventing the escape of the prey. The
food is swallowed whole. The esophagus (the tube
Figure 115. — Diagram to Show Organs of Frog.
connecting the mouth cavity and stomach) of the frog
can be stretched so that a comparative^ large animal can
be swallowed. There is no sharp limit between the esoph-
agus and the stomach, which is a long spindle-shaped sac
(Figure 115), larger than the rest of the digestive tube.
The small intestine begins at the back end of the
stomach as a small tube which makes several turns, and
finally enlarges into a region called the large intestine,
the last part of which is termed the cloaca (cl5-a/ca) or
common sewer. *
Two glands of importance belong to the digestive
INTERNAL STRUCTURE
117
organs
• the liver and the pancreas. The liver is a
large, dark-red, three-lobed organ that covers the ventral
(lower) surface of the stomach. The pancreas is a
whitish, small, irregularly shaped body attached between
the stomach and the intestine. Both of these glands
drain into the intestine just beyond the stomach. The
bile secreted by the liver is at first collected in a sac
called the gall bladder.
All of these parts of the alimentary canal are held in
place by a thin membrane (the mesentery, mOVen-te'r-y),
one edge of which is attached to the dorsal wall along the
line of the backbone and the other to the stomach and
intestine. A small gland (the spleen') is found in this
mesentery. The spleen has no duct connecting it with
any other organ in the frog. Blood vessels run through
the spleen and scientists believe that it is important in
making new blood corpuscles.
Lungs. — The lungs are hollow sacs that lie back of the
stomach, one on each side. In the freshly killed animal,
these can be filled with air by inserting a blow-pipe into
the windpipe and blowing air into them. The empty
lungs are about as large as the
blunt end of a lead pencil.
Kidneys. — The kidneys are
small red bodies lying close to
the back. Each one is connected
with the cloaca by a minute duct
(ureter). The urinary bladder
is attached to the cloaca (Fig-
ure 116).
Reproduction. — The male
frog has a pair of spermaries
(speYma-riz), one attached to
the front (anterior) end of each Figure 116.
// fat bodies
^•testis
kidneu
-unnogenital
duct
cloaca
118
AMPHIBIANS
nerve to nose
Olfactory Lobe
- Cerebrum
nerve
to
eye
Thalamencephalic^
Medulla ■-•-
y
Optic Lobe
Cerebellum
"--Nerve to ear
■ ..4th Ventricle
. nerve to arm
kidney (Figure 116). Each spermary is yellow in color.
The sperms escape through the kidney. In the female
frog ovaries, sometimes filled with eggs, are easily seen.
A long, closely coiled pair of oviducts (6'vi-dukts) opens
in front near the forward end of the stomach and in
the back into the cloaca. The eggs break through the
wall of the ovary and
enter the oviducts. As
the eggs pass down
through the oviducts,
they are coated with a
jelly-like covering that
swells in the water.
This jelly covering pro-
tects the eggs.
Nervous Syste?n. — The
nervous system of the
frog is more highly de-
veloped than that of the
earthworm. It consists
of a central part enclosed
in the backbone and cra-
nium (braincase). This
central nervous system
in all vertebrates is al-
ways found above the
Figure 1 1 7. - Central Nervous System digestive tube, and is di-
op Prop
vided into the brain and
the spinal cord, from which numerous nerves arise and
extend to all parts of the body.
The parts of the brain are the same as in man and
much easier to study. Beginning at the front (anterior)
end of the brain the parts are as follows (1) : small
olfactory (61-fak'to-ry) lobes, which are not sharply marked
nerve
to leg
INTERNAL STRUCTURE 119
off from the rest of the brain, and, as shown in Figure 117,
connect with (2) the cerebral (ser'e-bral) hemispheres,
which are oval in outline. (3) A short mid-brain region,
partly covered by the back part of the cerebral hemi-
spheres, connects the front and back part of the brain.
(4) Two large optic lobes, the widest part of the brain,
are just back of the mid-brain. (5) The cerebellum
(se'r-e-bel'lum) of the amphibians is small and easily over-
looked (Figure 117). The last region of the brain is the
(6) medulla (me-dul'la), which is occupied by a large
triangular cavity called the fourth ventricle.
The work which each of these regions of the brain does
is not sharply defined. The olfactory lobes receive the
smell stimuli. The cerebral hemispheres control muscular
action. When the latter are removed the frog loses all
power to initiate any movement and will sit still in a dry,
warm room for hours unless disturbed. This he never
does when the cerebral region of the brain is uninjured.
The mid-brain region is the passageway for all nerve-path-
ways that travel to and fro in the brain. The mid-brain
and optic lobes explain to the frog the sight stimuli. In
the frog, the cerebellum is less important than in man and
is poorly developed. The medulla gives off more nerves
than any other region of the brain. Here are found the
nerves to the face, tongue, ear, heart, and lungs. While
there is a great difference between the shape of the parts
of the brain of the frog and those of man, yet the work
done by each region is of the same kind.
The brain joins the spinal cord, and there is no external
sign to indicate where one begins and the other leaves
off. A definite number (ten pairs) of nerves leave the
brain proper and are devoted to the special senses of the
head and to moving the muscles of the throat and head.
The frog has ten other pairs of nerves joined to the spinal
120 AMPHIBIANS
cord (Figure 117). In a long salamander there are 20 or
30 pairs of nerves on the spinal cord.
LABORATORY STUDY
In connection with the study of the frog, the following additional lab-
oratory work should be done in order that the several organs of man
which are discussed in Part II may be better understood. Frogs that
have been preserved in formalin can be easily dissected. Examine the
digestive organs : first the mouth, then the esophagus, stomach, small
and large intestine, and cloaca. For convenience, the liver will have to
be removed. The pancreas can be seen as a small whitish structure in
the loop between the stomach and the intestine. The spleen is a round,
red organ usually found near the large intestine.
A pair of narrow kidneys lies close to the back and is connected by
ducts with the cloaca. The spermaries are found attached to each kid-
ney near the front end and the sperm cells escape to the exterior by the
kidney ducts. In the female frog the large ovaries occupy most of the
space of the body cavity. A pair of oviducts opens into the body cavity
just back of the stomach. The eggs escape from the ovary into the body
cavity.
The nervous system is enclosed in bone that is easily removed from the
dorsal surface. The brain should be studied and the following divisions
recognized : cerebral hemispheres ending in front in the olfactory lobes,
which are not clearly marked. Just back of these the two large roundish
optic lobes which are attached to the midbrain (thalamencephalori) , thal-
a-men-ceph'a-lon). The cerebellum is small, and the medulla passes into
the spinal cord without any sharp dividing line.
120. Development. — Late in March and early in April
the frogs gather in ponds to lay their eggs. The eggs are
surrounded by a jelly-like substance which holds them
together. As the eggs are being laid by the female frog,
the male frog spreads a large number of sperm cells over
the whole mass. These sperm cells make' their way
through the soft jelly and one of them must enter each
egg or it cannot grow into a tadpole.
As soon as the sperm cell enters the egg (Figure 119), it
begins to change from a solid, pointed body into a round
nucleus which is so much like the nucleus already in the
DEVELOPMENT
121
egg cell that none but experts in this study can tell which
came from the sperm cell and which from the egg cell.
These two nuclei come in contact and unite, leaving but
Figure 118. — Frog Eggs.
one nucleus in the egg (Figure 119). This last change is
fertilization, which is defined as the union of the contents
of the egg and the sperm nuclei. After this union is
completed the egg begins to divide into cells, as shown
in Figure 120, and finally a tadpole is grown.
Eg'g Nucleus Sperm cell Egg' Nucleus Sperm Nucleus Fused Nucleus
Figure 119. — Diagram Illustrating Fertilization in Frog Egg.
As soon as the young tadpole hatches, it attaches itself
to plants and lives for the first few days upon the food-
yolk within its own body ; the mouth forms, and horny
jaws develop. Then the tadpole begins to feed upon
122
AMPHIBIANS
minute plants and becomes dependent upon its own skill
to get food and escape its enemies.
For a time the tadpole breathes through gills. Two
sets are used. The first ones are on the outside of the
body and last for only
two or three days, when
internal gills form in the
throat and the tadpole
breathes much like a
fish.
121. The Tadpole Be-
comes a Frog. — In the
growth of the tadpole
into a frog the hind legs
appear first. Later the
front ones begin to show and as they develop the tail is
gradually absorbed. While these external changes are
going on, there are many complicated internal changes
taking place ; internal gills are disappearing and lungs,
nerves, blood vessels, and muscles are being formed to give
Figure 120. — Dividing Egg of Frog.
Figure 121. — Dividing Egg Becoming a Tadpole.
the new legs life and action. The internal lungs take
the place of the gills in the throat before the legs are
fully grown and such tadpoles can breathe only air. Ex-
plain in Figure 122 which tadpoles breathe by lungs
EVOLUTION
123
and which by gills. This complicated way of growing into
a frog is called metamorphosis and this term lias the same
general meaning that it did when used to describe tin;
growth of insects (page 16).
The tadpoles of leopard frogs become small frogs
in a single summer, but the tadpoles of bullfrogs and
Figure 122. — Two Stages in the Development of Tadpoles.
green frogs require two seasons to complete their develop-
ment. These latter tadpoles hibernate in the mud with
adult frogs and toads.
122. Evolution. — Evolution, in a larger sense, is the
theory or belief that all of the complex animals and plants
on earth to-day developed from the simpler animals and
plants of many generations ago. This theory tries to
prove itself through the careful study and investigation
of the relationships between animals and plants of the
present and those that formerly existed.
The study of the changes through which the egg of the
frog grows into a tadpole and then into a frog tells us
124
AMPHIBIANS
much about the way frogs have developed from fishes.
The tadpole breathes and eats like a fish ; but as soon as
lungs and legs are formed, it breathes and eats like a frog.
This same study of the tadpole also illustrates how ani-
mals may gradually have come to live on land. In the
early history of the earth there were hundreds of animals
and plants which are no longer known to science. The
skeletons, foot-prints, and whole bodies of many of these
are preserved in the rocks. Such remains are called fossils.
If all the animals, or one of each kind, had been pre-
served in the rocks, it would be easy to investigate these
Figure 123. — Fossil Shells of Animals now Extinct.
earlier animals and their relation to the living animals of
the present. But in our information there are great gaps,
which we are, however, gradually bridging. Apparently
unrelated animals have resemblances, so that in time we
may come to see that all animals are really related forms,
varying only in complexity of structure. One thing that
we must always keep in mind is that the plants and animals
which live now are but a small fraction of those which have
lived. The rocks have preserved the remains of only a
small part of the forms of the past. Many of the records
HEREDITY 125
of extinct animals and plants have been destroyed by decay
and heat so that much that would be valuable in solving
the question can never be found.
The study of the development of the frog also illustrates
two other general subjects, heredity (he-red'I-ty ) and en-
vironment (en-vl'run-ment).
123. Heredity. — The tendency of all young animals to
grow and live like their parents is called heredity and may
be defined as the transmission of physical and mental traits
from parent to offspring. There is no difficulty in recog-
nizing the new frog as a certain kind of frog. The color
markings on the skin are like those of the parents; it
grows to about the same size; eats the same kind of food,
and lives in the same region.
Every species of living thing is able to produce new
forms like itself, and heredity is always at work when
new plants and animals are being produced. Heredity is
best thought of as that quality of living matter which ex-
presses itself in the growing plant and animal by making
sure that it resembles its parents. Thus heredity deter-
mines that leaves of the right shape and size occur in the
proper place and that our fingers and thumbs grow on the
end of the arm in the usual way.
There has been much study of the question of heredity
and there is much yet to be learned. However, we know-
that we inherit from our parents and grandparents, our
complexion, the color of eyes and hair, our size, our re-
sistance to disease, our mental traits, and many other
characteristics.
In 1865 Gregor Mendel, abbot of Briinn, published t la-
results of experiments made with peas, which showed thai
crossing tall and dwarf peas resulted in all the offspring
being tall. But the offspring of these latter (the grand-
children, so to speak, of the original peas) might be cither
126
AMPHIBIANS
tall or dwarf. The proportions were regular and the re-
currence of tall or dwarf peas was so uniform that from
these- and other experiments later scientists evolved defi-
nite laws of heredity, known as the Mendelian Laws.
A detailed statement of these laws is beyond the prov-
ince of an elementary book, but it is now well established
that certain traits of parent plants and animals are repro-
duced in their offspring in regular and definite amounts
and proportions.
124. Environment. — This word is used in two ways.
First, it refers to general surroundings such as tem-
perature, moisture, and
seasons, as they vary
from year to year ; and
secondly, to immediate
surroundings. The frog
responds to the first by
hibernating in the win-
ter ; while the second
phase of environment
may be illustrated as
follows : the tadpole can
live only in water, and
if the pond dries up
before the frog stage is
reached, the environment
has been unsuited to the
tadpole. This often
happens when the eggs
are laid in a temporary
roadside pond which evaporates long before the tadpole
becomes a frog. All such tadpoles die unless they are
able to swim to some other body of water.
The birds that are able to fly avoid hibernating in the
Figure 124. — Tree Frog.
Notice the sticky disks at end of toes.
ECONOMIC VALUE 127
winter. They are able to adapt themselves to the change
in the seasons without burying themselves in the mud as
the frogs do.
Some of the birds do not migrate, but remain all winter
in the North. They have become so well adapted to con-
ditions that they are able to get their food where birds
that migrate would starve.
Man is the only animal which is able to live anywhere on
the face of the earth under the most varied conditions.
To realize this fully we have but to think of the different
surroundings of the Eskimo, Indian, Bushman, and of
ourselves.
Each animal and plant is directly dependent upon its
environment for food and a home.
125. Economic Value of Amphibians. — The toad is the
only member of the amphibian group that is of any great
value to man. It destroys many insects. Frogs eat a few
but hardly enough to entitle them to high rank as bene-
ficial animals. Their chief value is as food and as conven-
ient forms for dissection in biology courses.
SUMMARY
The Amphibians are an interesting group which illus-
trates how water animals may have become land animals.
The frog has well-developed sense organs, legs modified
for jumping, and feet for swimming. The skin is moist and
helps to serve as an organ of respiration. The color mark-
ings and the habits of the frog serve to protect him from
many of his enemies.
QUESTIONS
What animals belong to this class? How can yon tell them from fish ?
Where do the amphibians of your region live? Bow many kinds d<>
you know ?
128 AMPHIBIANS
See how many kinds of amphibian eggs you can find.
How long do tadpoles live before they become frogs ?
What do frogs and toads eat?
What is fertilization? Metamorphosis? Evolution? Heredity?
Environment ?
REFERENCES
Dickerson, The Frog Book.
Hodge, Nature Study and Life.
Holmes, Biology of the Frog.
Marshall, The Frog.
Morgan, Embryology of the Frog.
CHAPTER XII
REPTILES
Figure 125. — A Sea Turtle.
126. Reptiles. — Among the Reptiles (rep'tflz) are in-
cluded lizards, snakes, alligators, turtles, and crocodiles.
The Reptilia (Latin,
repo, to crawl) are char-
acterized by a covering
of bony plates, or scales,
in the skin, by the ab-
sence of gills in the
adult stages, and by the
presence of lungs.
127. Life History. — Unlike the amphibians, the reptiles
hatch directly into their adult form, only much smaller.
The young snake just
out of the egg or the
young alligator just
hatched is recognized
by its resemblance to
its parents.
There is no meta-
morphosis, as in the
frog. The reptiles lay
their eggs in protected
places and exhibit no
parental care for the
Figure 126. — Horned Toad, a Lizard.
Showing egg-capsules in which the
young are hatched.
eggs or for the young. Some snakes hatch their young in
the body of the parent and the offspring are born alive.
i If desired, this chapter may be omitted without affecting the sequence in
the book.
129
130
REPTILES
128. Turtles. — Turtles are easily recognized by their
outer skeleton. This skeleton is unlike the skeleton of
the starfish or crab, or of any other group of animals. The
Figure 127. — Bull Snake with Hen's Egg in Mouth.
skeleton of the turtle, composed mostly of skin plates, is
something like a box with a cover, the upper portion cor-
responding to the box itself, and the lower portion to the
Figure 128. — Bull Snake after Swallowing Egg.
cover. The box does not fit closely all the way around,
for there are places where the head, the tail, and the four
legs stick out. When the turtle is disturbed, the legs,
SNAKES
131
the head, and the tail are drawn inside, and the box is
pulled down tightly by muscles to meet the cover.
The term turtle is often applied to aquatic forms, and
the term tortoise to those living on land. Sea turtles
attain a length of six or
eight feet and weigh
Figure 129. — Head of a Rattlesnake.
Dissected to show the poison gland, a,
and its relation to the tooth. (Duver-
moy.)
sometimes as much as a
thousand pounds. The
flesh of the green turtle
and of the terrapin
(ter'ra-pin) is used for
food.
129. Lizards. — There
is a great variety of
lizards. A common
lizard is the chameleon
(ka-me'le-un), which has the power of changing the
intensity of the color in the skin by moving the color
material nearer the outer surface or drawing it away.
The horned toad of the Western United States is a lizard
with scales of varying length which give it a horny
appearance. Horned toads, instead of laying eggs, have
the eggs hatched while
yet in the oviducts and
the young horned toads
are born alive. A poison-
ous lizard is the Gila
(he'la) monster that oc-
curs in New Mexico and
Arizona. It has the poison glands in its lower jaw.
130. Snakes. — Snakes are legless vertebrates with long,
cylindrical bodies covered with scales. They move by
means of the scales (scutes) on the under side of the
body. Most snakes lay eggs, but a few bring forth living
Figure 130. — Rattles of Rattlesnake.
132 REPTILES
young. Since snakes eat insects, frogs, mice, rats, and
rabbits, they should be considered beneficial.
Rattlesnakes1 and copperheads are the most common
poisonous snakes of our country. Their jaws are provided
with fangs (Figure 129), by means of which a poison
is injected into their prey. Large snakes like the black
snake or blue racer of the United States, the boa con-
Figure 131. — Rattlesnake — -Poisonous.
Compare head with snake in Figure 132.
strictor of South America, and the python (pi'thon) of
Asia are constrictors. They are able to wind their bodies
around their prey and to crush it to death. The most
deadly snake in the world is the cobra (ko'bra) of India,
where thousands of the natives die annually from the bite
of this snake.
Snakes swallow their food whole, and as the teeth are
used merely for holding their prey, they point backwards.
1 The two most common rattlesnakes are the mountain rattler and the
massasauge (mas-sa-sa'ge).
ALLIGATORS AND CROCODILES
133
Figure 132. — Garter Snake — Harmless.
131. Alligators and Crocodiles. — Crocodiles are found in
the Southern United States, South America, Africa, and
India. Alligators are found in stagnant pools in the
Figure 133. — Eight-foot Florida Alligator.
134
REPTILES
Southern States. Crocodiles resemble alligators but have
narrower mouths.
132. Adaptations. — Reptiles are peculiarly adapted to
their environment. Snakes that live in trees are some-
times the color of leaves or bark. Some that are harmless are
colored much like poisonous snakes. An adaptive feature
of the crocodile is a fold of skin which shuts off the mouth
Figure 134. — Alligator Nest.
from the throat and prevents water from entering the
throat while the crocodile is drowning its prey. The old
world chameleons have their feet modified for clasping
branches. In the case of the turtles, those that live in
the sea have paddle-like feet for swimming, while those
that live partly on land and partly in the water have toes
with webs. Lizards are almost always of about the same
color as their surroundings.
SUMMARY
135
SUMMARY
The reptiles always use lungs for breathing. They
usually have scales or bony plates in the skin and have
either two pairs of appendages (turtles, lizards, alligators,
crocodiles) or none (snakes). It is important to learn to
recognize poisonous reptiles, as their bite is dangerous.
Figure 135. — Poisonous Lizards — The Gila Monster.
LABORATORY QUESTIONS
From models or preserved specimens the difference between the harm-
ful and harmless reptiles should be worked out. The living turtle can be
studied easily. Its special skeleton is an illustration of protective adapta-
tion. Notice how the nostrils of the aquatic turtle can be closed. How-
does this help the turtle ?
QUESTIONS
AVhat are the most common snakes in your vicinity? Are fchey
poisonous? How can you tell? Where do they live? What do they
eat? How many kinds of turtles do you know? Where do they live?
REFERENCES
Ditmars, The Reptile Book.
Jordan, Kellogg and Heath, Animal Studies.
Linville and Kelly, General Zoology.
Reese, The Alligator and its Allies.
CHAPTER XIII
BIRDS
133. Birds. — Birds are the only vertebrates covered with
feathers. Their front legs are modified into wings.
Among some birds, like the penguins (pen'gwinz) of the
Antarctic region, the wings are not used for flying but to
assist in swimming. In others, like the eagles and condors,
the expanse of the wings
is sufficient to enable
them to fly away with
young lambs and large
fish. Between the small
wings of the penguin
and the great expanse of
the wings of the eagle
and the condor there
are many variations.
Bird wings are adapted
to the needs of their
owners. Sailing birds, like the gulls, have long, slender
wings, while ground birds, like the partridge and pheasant,
have short wings capable of rapid, short flights. Those
birds that make the most use of wings have them best
developed. An example of underdevelopment, which has
been increased by domestication, is seen in the domestic
fowl, a ground bird, which makes little use of its flying
powers, and is incapable of sustained flight.
The legs of birds also have many variations. In the case
136
Figure 136. — Grebe.
BIRDS
137
of the eagles, hawks, and owls there are powerful claws for
seizing and holding prey, while ducks and geese have
long and webbed toes, adapted to swimming. Seed-eating
birds have weak claws which serve merely for perching.
Chimney swifts, that spend most of their time in flight
searching for food, have well developed wings, and feet
used for clinging. Study Figures 139, 140, 149, 155.
Figure 137. — Herring Gulls.
The beaks of birds show great variation and adaptation
for defense and food getting. Hawks, owls, and eagles
have the upper jaw curved over, hooked, and adapted for
tearing the food; herons and bitterns have the beak modi-
fied into a long, pointed weapon of offense and defense ;
grosbeaks (gros'beks) and finches have a short, stout beak
for crushing seeds and other hard foods; while humming
birds have a long, slender beak which in some kinds is
curved so that they may reach the bottom of certain
flowers. Study Figures 137, 143, 144, 153, 154.
138
BIRDS
The birds show a
number of other special
adaptations which are of
use to them. These are
hollow bones, a keeled
sternum (breast bone),
and a high body tem-
perature.
The skeleton of a bird
shows a prominent ridge
on the breast bone.
This is the keel of the
sternum, which serves
as a place of attachment
for the large wing mus-
cles (Figure 139). The
lungs of the bird are
small, but air tubes
extend into the bones,
so that the body of the bird is relatively lighter than
that of animals with solid bones.
Birds lead an active life, which means that they use a
great deal of energy. This energy comes
from the oxidation going on in the body.
In birds, oxidation is more rapid than in
other vertebrates, owing to the fact that
they almost completely change the air
with each breathing movement and thus
secure a greater supply of oxygen. The
rapid oxidation requires a large supply
of food to be digested and assimilated
rapidly and it also makes the normal
J Figure 139. —
body temperature of birds higher than Skeleton of Mal.
that of other vertebrates. lard Duck.
Figure 138. — Adult Screech Owl.
CLASSIFICATION
139
Figure 140. — Different Kinds of
Birds' Feet.
134. Plumage. — The
feathers of birds show
great variety in form and
color. In some species
there are certain colors
which always predomi-
nate on the males, while
the females have little
color ; in other species
it is hard to distinguish
between the sexes. The
brilliantly colored males
are supposed to attract
the females at the mating season, while the dull colored
females are inconspicuous and less likely to be attacked
by enemies while hatching their eggs, or caring for their
young. We may say,
therefore, that they are
protectively colored.
The color of birds varies
during the first two or
three years of life.
135. Classification. —
Birds are usually di-
vided into groups ac-
cording to their struc-
ture. The shape and
size of the beak and of
the feet and wings are
the characteristics most
used in the general
classification. This is
illustrated by a single
Figure 141. — Loggerhead Shrike. group of birds, the
140
BIRDS
Figure 142. — Young of Red-tailed Hawk — Beneficial.
hawks, owls, and vultures, which are given the technical
name of Raptores (rap-t5'rez Latin, rapere, to ravish),
birds of prey. The bird books describe the Raptores as
Figure 143. — Head of Young Eagle.
CLASSIFICATION
141
follows: toes four, three in front and one behind, except
in the vultures ; all toes armed with strong, sharp, curved
talons (tfil'iinz); bill with a cere (ser : Latin, sera, wax)
or covering of skin at its base through which the nostrils
open, very stout and strong, the upper mandible tipped
with a sharp pointed hook.
In addition to this classification by structure, which is
essential for a careful study of birds, they are also classi-
fied by their habits. For example, birds are divided into
four classes based on
their migratory habits.
Birds like the downy
woodpecker and English
sparrow are permanent
residents throughout
their range, that is, they
can be found within
given limits at any time
of year, while bobolinks
and humming birds are
summer residents, mi-
grating southward at
the end of the season.
Birds like wild geese, fox sparrows, and the like, arc
transients, stopping along their migratory route for rest
or food or to escape unfavorable weather; while such
birds as the snowy owl, great northern shrike, and red-
poll are winter visitants which have migrated to us from
the North when the cold became excessive and the food
supply diminished.
Birds are classified also by their nesting habits. Some
birds, like the meadow lark and bobolink, nest in the open
field, and their nests are made inconspicuous rather than
inaccessible; other birds, like certain hawks and eagles,
Figure 144. — The Robin.
Sometimes a winter resident.
142
BIRDS
Figure 145. — Nest of Goldfinch.
Nest of altricial bird.
build their nests in
tall trees, making them
conspicuous, but inac-
cessible. Still others
build like the oriole
at the end of slender
branches where they
are out of reach of
animals. Birds like
the kingfisher, sand
swallow, and puffins
build their nests at the
bottom of a burrow in
the ground.
136. Nest Building. —
Birds show great variation in nest building. Some
build a large nest with materials loosely put together;
others build small nests of neatly woven material, and
some birds, like cowbirds, build no nest at all, but lay
their eggs in the nests of
other birds and leave the
work of caring for their
young to the foster parents.
The number of eggs that
birds lay in their nests varies
from one to as many as thirty
or forty. The time required
to hatch the eggs varies from
ten days to six weeks. Birds
whose eggs hatch in ten days
or two weeks are called al-
tricial (al-trl'shal : Latin,
altrix, nurse), for such young
are hatched helpless, blind,
Figure 146. — Nest of Least
Bittern.
MIGRATION
143
and with little down. Eggs that hatch in from three to
six weeks develop well-formed young, able to run around
within ten to twelve hours after hatching. These are
known as prcecocial (pre-ko'shal : Latin, prae, before;
coquere, ripen). Such birds have little need for a sub-
stantial nest and few of them build one. The robin is
Figure 147. — Mourning Dove.
altricial, and the domestic fowl prsecocial (Figures 1 |.~>
and 146).
137. Migration. — Because they are provided with wings
and the power to fly long distances, birds are able to move
from one region to another for the purpose of finding food
and rearing young. The precise cause of migration is
still unknown. Birds in general migrate to a warmer
climate in the fall of the year and return to the cooler
region in the springtime. In some cases birds cross the
equator in migrating. For example, the bobolink nests in
144
BIRDS
the Northern United
States and passes the
winter in South Amer-
ica, migrating a distance
of over five thousand
miles. In the case of
the robin the migration
is limited to a short
flight to the south to
some protected swamp
provided with water and
food. A probable cause
of migration is the fail-
ure of food supply as
cold weather comes on
in the fall.
138. Economic Impor-
tance of Birds. — The
chief food of birds is
insects, such as plant lice, larvae of beetles, butterflies,
moths, borers, etc. The chickadee, for example, feeds
on plant lice as well as
other foods ; the downy
woodpecker feeds on
codling moths and
borers ; the nuthatches
and brown creepers feed
on insects and insect
eggs that are hidden in
crevices and under loose
pieces of bark. Other
useful birds are the song
sparrow, chipping spar-
Figure 148. — Chimney Swift and Nest.
Part of the birds have been crowded out.
row, robin, bluebird,
Figure 149. — Junco.
A transient bird nesting in Canada, and
on the high hills and mountains of
the Northern states.
ECONOMIC IMPORTANCE
14.-)
Figure 150. — Female Bobolink.
wren, blackbird, etc., which
feed principally on insects
that are found on or near
the ground. The insects
that fly, like mosquitoes,
gnats, and house flies, are
eaten by swifts, swallows,
night hawks, king birds,
and fly catchers.
Among the hawks and
owls is found a long list
of beneficial birds, for the
screech owl, red-tailed hawk,
and the red-shouldered hawk are almost without excep-
tion valuable as destroyers of shrews, moles, mice, rats,
weasels, and rabbits. The hawks that are partly harmful
are the sharp-shinned hawk, Cooper's hawk, and the marsh
hawk. All of these help themselves to poultry and feed on
small beneficial birds
like the song sparrow
and bluebird.
The exact relation of
birds to agriculture and
the foods that they cat
has been a subject of
study by the Depart-
ment of Agriculture.
Fisher reports the fol-
lowing' results in his
analysis of the stomach
contents of 220 red-
shouldered hawks : ;,» of
them contained poultry,
Figure 151. — King Bird. 12 of them held 102
146
BIRDS
Figure 152. — Young Crows in Nest.
mice, 40 of them other mammals; 20 of them reptiles;
39 of them amphibians ; 92 of them insects ; and 16 of
them spiders. A similar analysis of 133 stomachs of
Cooper's hawks shows the following : 34 of the stomachs
contained poultry or game birds, 52 contained other birds ;
11 of them mammals ;
1 of them a frog ; 3 of
them lizards, 2 of them
insects, while 39 of them
were empty.
Aside from being of
value in the destruction
of insects, birds destroy
waste matter and dead
Figure 153. — Kingfisher. animals lying Oil the
ECONOMIC IMPORTANCE
147
ground. The vultures
and buzzards of the
South and West eat
dead animals. The
gulls of the sea and
lakes destroy refuse
thrown upon the sur-
face of the water. The
eagle is also a scavenger
as it eats dead fish that
float on the surface of
the water, or small dead
animals thrown out in
the open on the land.
Crows also eat dead
fish.
There is also a group of birds that lives largely on seed,
and such birds destroy vast amounts of weed seeds.
Among the seed eaters are the quail, grouse, pheasant,
goldfinch, sparrows, bobolink, and meadow lark. A
Figure 154. — Hairy Woodpecker
Eating Suet.
Figure 155. — Male and Female Cowbirds.
148
BIRDS
— -e-
• /I?" •
-,//>-J\y f-*\ <f-z\
— 7Ar"— —•-<?--
Figure 156. — Plan for Bird House.
definite plan for bird study is suggested in the Ap-
pendix. There are many facts which we should know
about each bird which are more important than knowing
its name.
One of the best times to study birds is in the winter by
means of feeding stations (Figures 154, 155). If you have
trees near your home, especially if you live on the edge of a
city or in a country
town, it is a simple
matter to get birds to
come to you. It will
take a little time for the
birds to learn that you
are friendly. The first
ones to come will be
house sparrows and their
noisy chatter helps to
attract other birds.
Each feeding station
may have one kind of
food, as suet, seeds, bread
crumbs, or whole grain.
Some of the birds will
visit all of the feeding places, but in general birds are
either seed-eating or suet-eating.
At a suet station one may expect to see the following :
Screech owl, woodpecker, blue jay, crow, tree sparrow,
junco, rosebreasted grosbeak, myrtle warbler, brown
creeper, nuthatch, chickadee. At a hemp and millet seed
station: Pine grosbeak, red poll, goldfinch, pine siskin,
vesper sparrow, white-crowned sparrow, white-throated
sparrow, song sparrow, junco, nuthatch, chickadee, purple
finch. At a bread crumb station : Blue jay, crow, tree
sparrow, brown creeper. At a station where whole grain
Figure 157. — Plan for Bird House.
SUMMARY 149
is used : Blue jay, crow, white-breasted nuthatch, chickadee,
quail, grouse.1
SUMMARY
Because of their feathers birds can be easily recognized.
The fore limbs are adapted for flying, and as such vary in
size. The feet are modified for swimming, running, perch-
ing, or tearing ; while the jaws are large and powerful, or
small and weak, depending on the habits of each bird.
The classification of birds according to their habits makes
it easy to learn about them. Birds are of great economic
importance in destroying many kinds of insects that are
detrimental to man. This explains why they must be
protected by law.
FIELD SUGGESTIONS
The plan for field study will be found too extensive for the time avail-
able in this course, but many are anxious to continue studying birds for
several years, and the plan in the Appendix suggests a systematic method
from the habit point of view. Certain parts of this plan should be under-
taken whenever birds are taken up in the course. Students will find this
an interesting way to spend part of the summer vacation.
QUESTIONS
How many birds do you know ? What do they eat ? Do they remain
all winter ? Which ones migrate ? Where do they nest ? What time of
year do the young leave the nest ? Why are the birds beneficial ?
REFERENCES
W. L. McAter, How to Attract Birds in North Eastern United States
Farmers' Bulletin 621.
Chapman, Bird Life.
i W. L. McAter, How to Attract Birds. Fanners' Bulletin 621,
CHAPTER XIV
MAMMALS
139. The Mammals are the most highly developed of the
vertebrates. They are warm blooded (the body tempera-
ture remaining the same in winter and summer), breathe
by means of lungs, and are provided with milk glands to
nourish the young. Most mammals are covered with
hair. A muscular wall (diaphragm) subdivides the body
Figure 158. — Skeleton of
Dog.
Figure 159. — Coyote.
cavity into parts. The upper part contains the heart and
lungs, and the lower part contains the stomach, intestines,
liver, and other organs. At birth the young look like the
parents.
Most mammals have two pairs of limbs. The fore limbs
may be variously modified for different uses, as for walk-
ing in animals like the horse, for climbing and for food-
150
THE MAMMALS
151
Figure 160. — Gray Squirrel.
Figure 161. — Young Gray Squirrel
LeavIng its Nest.
Figure 162. — Young Foxes.
Figure 163. — Bat Hibernating.
152
MAMMALS
Figure 164. — Brown Bat.
Showing formation of wings.
getting in the squirrel, for burrowing and locomotion in
the moles, for flying in the bats, and for swimming in the
seals. In all fore limbs
of mammals, even in
those as different as the
leg of the squirrel, the
flipper of the seal, and
the wing of the bat, the
arrangement of the
bones is the same. The
hind legs of mammals do
not show so much varia-
tion as the fore limbs.
But in some cases, as in
the whale, the hind legs
have practically disap-
peared through disuse,
and there is no external
evidence of them. Some
animals, like the bears,
walk on the soles of their
Figure 165. — Flying Squirrel. feet, and some, like the
THE HORSE
153
cats and the dogs, walk on all of their toes. In some
mammals there is a variation in the number of the tots.
For example, the cow
walks on two toes and
the horse on one toe,
the hoof being a modi-
fied toe nail. In such
cases the other toes are
entirely lacking or rudi-
mentary (not perfectly
developed).
140. The Horse.— The
horse is interesting be-
cause it has been associ-
ated with man since
the pre-historic period
known as the Stone Ace.
Figure 166. — Deer Mouse.
A nocturnal rodent.
It has been suggested that man
"first hunted horses for food, then drove them, and finally
Figure 167. — Sea Lions.
154
MAMMALS
Stomach of Sheep
Oesophagus
-Rumen
Abomasum
'Reticulum
'Intestine
Figure 168. — Stomach of Sheep.
Sheep, deer, and cows chew the "cud"
and all have stomachs of several
compartments.
used them for riding and
as beasts of burden."
The fine animals which
we see to-day have grad-
ually developed through
this long time from a
small animal about the
size of a fox terrier.
The earliest remains of
the feet of the ancient
horse show that it had
four toes and the remains
of a fifth in the front foot, while the hind foot had three
toes and the remains of
a fourth. The horse and
the deer, which also has
many stages preserved
in the rocks, afford ex-
amples of the manner
in which some of our
present animals have
developed. This is an-
other good illustration
of evolution.
141. Economic Importance of Mammals. — When we con-
sider the value to man
of horses, cattle, sheep,
pigs, and goats in this
country, and the value
of the camel and rein-
deer in other countries,
we can see the great
economic importance of
Figure 170. — Young Rabbits. mammals. Mammals
Figure 169. — Skunk.
ECONOMIC IMPORTANCE
1 .").")
Report on Mammals to be filled out first from general knowledge, later
extended by trips to fields, woods, or parks.
Kinds
Wheee
Found
I'< >OD
Kind of
Food
I. Ill IS
W'lNTKK
Life in
Si mm Kit
I'.l M II' 1 \l
II u:\li ii
are useful as food, companions, beasts of burden, and for
clothing. The furs of wild animals and the leather and
the wool of domestic animals are most important in
protecting the body of man from unfavorable weather.
Among the domestic
animals the horse is
useful for driving and
draught work, and the
cow for its flesh, milk,
and butter. The sheep,
through its flesh and
wool, is an economic
factor of great impor-
tance in civilization.
There are harmful
mammals like gophers
(go'ferz), prairie dogs,
rabbits, rats, and mice.
Lions and tigers some-
times kill human be-
ings. Weasels, skunks,
and mink are often
harmful in poultry
yards.
Figure 171. — Elk.
156
MAMMALS
Figure 172. — Virginia Deer.
Figure 173. — Fawns of the Virginia Deer.
ECONOMIC IMPORTANCE
157
Figure 174. — Coon.
Figure 175. — Young Woodchucks.
158
MAMMALS
Figure 176. — Camel. The Ship of the Desert.
In making long trips across the desert, the camel is able to go without
drinking. During these journeys, the hump grows smaller as the fat in
it is used as food. This food is gradually changed until part of it be-
comes water. We might say that the fat in the camel's hump is a
special water reservoir.
Figure 177. — Buffalo.
These sturdy animals once roamed the plains in great numbers.
were not protected in park preserves, they would now be extinct.
If they
SUMMARY 159
SUMMARY
The animals which are called mammals are covered with
hair, and nourish their young with milk. There are nearly
always two pairs of appendages that undergo much modi-
fication according to the habits of the animals. ( )ur
domestic animals which serve us in so many ways have grad-
ually developed into their present form and usefulness.
Man had to learn first how to use the fur and skin of wild
animals, then how to improve the quality of the fur and
skin by careful feeding and breeding of the domesticate!
animals.
FIELD SUGGESTIONS
If you are where you can visit a Zoological park it is an easy matter to
learn how to distinguish the different nianimals, a thing which every one
should be able to do. There is another line of study which consists in
selecting some one or two of the common mammals, such as squirrels, and
making a thorough study of them from week to week, month to month,
year after year, until you feel thoroughly acquainted with them. A third
line of study is that of hibernation. Some mammals do not hibernate,
some do so only during cold snaps, while others go to sleep for the entire
winter.
QUESTIONS
How do you tell a mammal from other vertebrates ? What mammals
live near your home ? What do they eat ? Where do they spend the
winter ?
REFERENCES
Davenport, Domestic Animals and Plants.
Linville and Kelly, Zoology.
Plumb, Types and Breeds of Farm Animals.
Stone and Crane, American Animals.
PART II
HUMAN BIOLOGY
CHAPTER XV
LIPE PROCESSES OF MAN
142. Adaptation. — Adaptation includes all the variations
in structures and habits which have been formed by an
animal or plant to enable it to live in its own particular
environment. Thus certain forms are adapted to living in
the tropics, others in the temperate regions, and still others
in the arctic regions. Living things which can adapt their
lives to our northern winters do not need to migrate south
as cold weather comes on in the fall. The frog cannot
migrate, but hibernates in the mud.
Man is the best adapted of all animals to live in all parts
of the world. When and where man began to live on the
earth is not accurately known, but it was many thousands
of years ago. He has been able to spread over the face of
the earth because he can control his surroundings, that is,
if he happens to live where there are many enemies, he in-
vents destructive weapons and kills his enemies or drives
them away. This is true even of disease, — man's greatest
enemy. Again, most animals are either flesh-eating or
plant-eating, but man is both, and because he lias learned
to eat a greater variety of both kinds of food than any
other animal, it is easier for him to live and to raise his
children in all climates.
161
162
LIFE PROCESSES OF MAN
All of the animals so far studied have been able to live
only in their own limited surroundings. The grasshopper,
the earthworm, the paramoecium, and the crayfish are not
found in the sea or arctic regions. If the paramoecium or
the crayfish is placed in sea water, where the lobster and
many unicellular animals live, it dies. On the other
hand, if the starfish or some of the seafish are placed in
fresh water, they die. All of these animals are adapted
to their own limited surroundings.
Scientists give four reasons in explaining why animals
and plants are not adapted to live in all parts of the
world: (1) lack of suitable food ; (2) failure in adapting
their lives to the peculiarities of climate ; (3) too many
enemies ; (4) inability to raise their young.
STUDENT REPORT
The following table points out some of the common adaptations
in animals. How are they related to the animal's success in life ? Name
some other habits which help to protect animals.
Home
Protection
7.
2,
'SI
W
H
Z
o
z
H
c
(J
Z
(—1
o
Eh
w
J
w
S5
-4
fa
Z
z
H
n
1-1
o
>
M
W
l-t
P
H
fc
H
■-
63
W
OS
o
"4
z
03
w
o
o
H
Eh
H
a
-sj
05
X
©
>■
_!
H
Eh
Q
O
<
£
M
•A
<
©
K
W
<
<
W
<
*
fe
ft
o
W
a
Earthworm ....
Grasshopper ....
■
English Sparrow . .
,
Bog
YOUTH, MATURITY, OLD AGE
163
143. Youth, Maturity, Old Age. — The life of man is
divided into three general periods, which are youth, the
period of maturity, and the period of old age. These same
terms are given when describing the life of animals and
plants.
Youth is the period when living protoplasm always
grows, if furnished with proper food. This is the time
when boys and girls grow taller and
heavier each year ; when the tree grows
new leaves and the limbs become longer;
and when the small puppy is turning
into a full grown dog. During this
period of change the boys and girls, the
tree, and the puppy are all nourished
by food and this makes it possible for
them to grow.
Maturity is the period when man
ceases to grow taller, although he con-
tinues to eat food as he did during the
period of youth. The living proto-
plasm in his body does not increase in
amount. The same can be said of the
tree, for it does not grow taller ; and
the puppy of last year has become a
full grown dog. During this period
Figure 178. — Ali-
mentary Canal of
Frog.
Compare with Fig-
ure 179. In what
are they alike? In
of maturity, each living organism is what different?
able to repair its body as fast as the
body wears out. The period of maturity varies in all
living things ; in some butterflies lasting but twenty-four
hours, in man continuing for about twenty-five years.
Old age in man begins when the bodv wastes faster
than it is repaired, and in the tree when growth Is over
and decay begins. During this period of old age all
living things use food as they did in youth and maturity,
164
LIFE PROCESSES OF MAN
but the body wastes faster than it can be repaired and
death is the final result. Old age occurs at different
ages in different individuals ; and the same is true of
animals and plants.
STUDENT REPORT
Fill out the following table and describe the digestive system of the
animals studied thus far in Part I. This will help you to understand
better the parts of the digestive system of man and the work that each
part does.
Paramo3cium
Hydra
Earthworm
Frog
Man
Etc.
One Cell
Man y
Cells
No
Digestive
Tube
Digestive
'iUBE
No Well
Defined
Digestive
Glands
Which
Ones
Require
Food ?
144. Digestive Organs. — The digestive organs of man
consist of the same parts which have already been described
for the frog. Each region of the digestive organs is more
perfectly developed and the biological principle, the di-
vision of labor, readies its highest -development in man.
The parts of the alimentary canal in man are : the
mouth, containing the teeth, tongue, and glands ; the
throat or pharynx; the esophagus, the stomach, the small
and the large intestine. The last part of the large in-
testine is called the rectum. These several parts form a
continuous tube, and each does a particular work in di-
gestion (Figures 178 and 179).
The mouth is lined with a soft membrane, kept moist by
the saliva secreted by three pairs of glands, and poured
THE DIGESTIVE ORGANS
if..-)
tongue
bladder
oesophagus
stomach
into the mouth in sufficient
quantities to moisten the dry
food and thus assist in swallow-
ing. The tongue is a muscular
organ and bears on its upper
surface many small fleshy pro-
jections called papillae (pa-
pil'le : Latin papilla, bud),
some of which are fairly large
and are arranged on the back
of the tongue in the form of
a V (Figure 180).
Our power to taste sweet,
sour, bitter, and salt, which are
the four fundamental tastes in
man, is due mainly to certain
nerve cells located on the larger
papillae. The food stimuli received by the special sensory
cells of the papilhe are carried to the brain by the taste
lar$e
intestine
pancreas
small
intestine
appendix
Figure 179. — Alimentary
Canal of Man.
I
I l
Figure 180. — Tongue.
Figure 181. — Taste Cells.
The taste nerve ends among
these cells.
166
LIFE PROCESSES OF MAN
nerves. In the brain the food stimulus is interpreted as
sweet, sour, or bitter (Figure 181).
LABORATORY STUDY
Blindfold in turn several members of the class and have each hold his
nose while a small amount of some highly flavored food is placed on the
tongue. Such common foods as maple syrup, vanilla extract, marmalade,
jams, etc., are admirable for this test. Make a record of each test. This
experiment will prove that we do not taste flavors. Remove the hand from
the nose and again taste the same substances. This time there will be no
difficulty in telling the name of the substance because it has been smelled
as well as tasted.
The roof of the mouth is called the palate. The front
part contains supporting plates of bone and is therefore
called the hard palate. The back part (the soft palate) is
a thin sheet of muscle covered by the mucous lining of the
mouth. The palate separates the mouth from the nasal
cavity. Beyond the soft palate is the throat cavity called
the pharynx. This is a funnel shaped cavity, having
two openings at its lower end, the front one being
the opening into the windpipe which leads to the lungs,
and the rear one, the opening into the esophagus. In
the upper part of the
pharnyx on each side, is
the opening of an eusta-
chian (u-sta/ki-an) tube
which passes to the
middle ear.
Teeth. — Just back of
the lips are the teeth.
In adults there are
thirty-two, sixteen in
each jaw, belonging to
four classes according to shape. In front are the eight
incisors (in-si'zers) with sharp cutting edges ; next the
Figure 182. — Milk Teeth.
Age 2>\ to 4 years. Notice the per-
manent teeth deeper in the jaws.
THE DIGESTIVE Olid ASS
16!
four sharp-pointed canines (ka/nins), aiid back of the
canines the eight pre-molars (pre-mo'lers) Bhaped for
tearing and crushing, while the remainder of the teeth,
twelve in number, are the flat-topped molars which do
most of the grinding of the food.
Care of the teeth. — We all know that the teeth are
hard. That, however, does not prevent them from becom-
ing broken by carelessness or accident, or from decaying
because of neglect. When the teeth are not cleaned, a
substance called tartar forms on them, which prevents
the bacteria from being rubbed off and sometimes pushes
the gums away from the
teeth. The bacteria
cause food particles to
ferment and form acids
which dissolve the
hard outside covering
(enamel) and then
rapidly the softer parts
of the teeth. This re-
sults in toothache, a
foul breath, and the im-
perfect chewing of the food. The teeth should be brushed
after each meal to remove particles of food and particu-
larly sugar which ferments easily. At least once a year
there should be a visit to the dentist who will remove
those portions of teeth that are decayed and will lill
cavities, thus preventing further decay of the teeth. The
value of good teeth cannot be overestimated.
The esophagus is a nearly straight tube connecting the
mouth with the stomach. It passes through the diaphragm
(Figure 208), enlarges, and becomes the stomach. As
soon as one swallows, control of the food is lost,
and further action becomes involuntary. Two sets of
Figure 183. — Permanent Teeth.
His
LIFE PROCESSES OF MAN
Figure 184. — Pear-
shaped Human
Stomach.
muscles, one extending lengthwise, the other around
the esophagus, act together in forcing the food or water
into the stomach. This explains why we
can drink from a brook when the head is
much lower than the stomach.
Stomach. — In man the stomach is the
largest section of the digestive tube, and
it has a capacity of about three pints.
It is usually described as pear-shaped
although there is much variation in its
form (Figures 184 and 185). At the point where the
esophagus joins the stomach there is a muscular ring
(cardiac valve, kiir'di-ak) which ordinarily prevents the
food from passing again into the esopha-
gus. In vomiting, this valve becomes
relaxed. The opening at the larger
and lower end of the stomach is guarded
by a similar valve (pyloric, 23i-16Vik)
which serves to retain the food in the
stomach until certain digestive changes
have taken place.
The intestine has two parts, a small,
much coiled tube about an inch in
diameter and about twenty feet long
called the small intestine; and a large
section about five feet long and four
inches in diameter, bent in a rough
p shape and called the large intestine.
At the junction between these two miliar to physicians
regions projects a short sac, the vermi- and is called the J_
■p y s ~- i' « j.* „ , shape. — Dr. C. F.
jorm appendix (vermi-form ap-peiv- potter.
diks). The disease called appendicitis
(ap-pend-i-si'tis) affects this organ. The large intes-
tine ends in a special region called the rectum. The
Figure 185. — X-ray
Photograph of
Human Stomach.
FOOD
im
Figure 186. — X-ray Photo-
graph of Appendix and
Part of Large Intestine.
The constrictions are natural.
opening of the rectum to the
outside is the anus (a/ntts).
Glands. — A gland is a group
of special cells which secrete a
fluid. The glands which pro-
duce the digestive fluids are
(1) the three pairs of salivary
(sal'i-va-ry) glands, located
below the ear, and beneath the
tongue and lower jaw ; (2) the
numerous gastric (gaVtrik)
glands found in the lining of
the stomach, possibly 5,000,000
in number (Figure 187) ; (3)
the pancreas; and (4) the liver,
the largest gland in the body.
145. Food. — One of the best definitions of food is the
following. Food is that which when taken into the body
builds up tissue or yields energy. All organic foods or
foodstuffs are divided into three classes,
the proteins (pro'te-ins), the cdrhoh yd 'rates
(kar-bo-hi'drats), and the /ate. This classi-
fication is made whether we studv the
foods of a plant, an animal, or of man.
Scientists are able to tell to which class
meat, bread, oatmeal, milk, and all other
foods belong by finding out the chemical
composition of each. The chemists have
made a thorough study of food and tell
us that certain chemicals are present in
each of the three classes of foods. Defi-
nite chemical tests tell us to which of
these three classes any given article of food
Figure 187. — \ ° . _ .
Gastric Gland belongs. In general it may be said that the
170
LIFE PROCESSES OF MAN
proteins are necessary for the growth and the repair of the
bodv, and that the carbohydrates and fats furnish heat to
keep the body warm, and energy for muscular work. The
unused fat is stored up as fatty tissue. All classes of
food are found in the various foods obtained from plants.
Some, like honey, are nearly pure carbohydrate, while the
English walnut contains, in addition to fat, a large quantity
£t^3^'"«~^- v3"'^r*0
>
;-=?cj
*
Figure 188. — Microphotograph of Stomach.
The stomach is an organ composed of several tissues arranged in
layers. The gastric glands are in the innermost ragged layer and
look like rows of black dots.
of plant protein. Animal foods can furnish us with only
proteins and fats. In primitive times man used a re-
stricted diet and led an active out-of-door life. To-day
man is living on a mixed and varied diet. This is to be
regarded as an acquired habit and one that is questionable
when carried to an extreme. The question of how much
to eat is a modern problem, and on its solution depend our
health, length of life, and energy for work.
Thomas Henry Huxley (1825-1895) was a celebrated English
biologist. As a young man he made a trip around the world in
H.M.S. Rattlesnake, which was on surveying service in Australasia.
On reluming home Huxley devoted himself to the study of biol-
ogy. He held a number of important academic positions and
was made President of the Royal Society in 1883.
Huxley was one of the most laborious workers in biology. He
rearranged the animals in new classes and discovered remarkable
similarities in their development. He is celebrated for his theory
of protoplasm and for his able advocacy of the views of Darwin.
Huxley showed great skill in putting the conclusions of science
into simple language.
DIGESTION
171
STUDENT REPORT
Animals eat a large variety of things, parts of which serve to furnish
energy or to nourish the body. In the following report, work out the
sources from which the animals derive their food. To what extent ;ue
they alike ?
Para-
mecium
HVDUA
Earth-
worm
Frog
Man
Flies
Minute plants . .
Minute animals
Flies
Add food of man .
146. Digestion. — Digestion begins in the mouth. The
teeth break up the food and mix it with the fluid of the
mouth, the saliva. During this process, sugars and
starches are changed into soluble sugars. The fluids of
the mouth are usually slightly alkaline (al'ka-lm or lin,
a chemical term, the opposite to sour or acid), but as soon
as the food passes into the stomach it enters an acid (sour)
medium, and the digestive action of the saliva is destroyed
in a short time by the stomach fluid. For this reason, the
sugar and starch undergo no further digestive changes
until they reach the intestines.
Into this acid medium of the stomach, the gastric glands
(Figure 179) pour out the gastric juice (a digestive fluid),
and the pepsin in this juice acts on the proteins so that
they can later pass through the walls of the intestines. In
the stomach the heat of the body dissolves some of the fats
into oils, but many of the fats used as food remain solid
at body temperature and are unchanged in 1 lie stomach.
After one or two hours the food passes into the intes-
tine and undergoes further changes in another alkaline
medium. Here the pancreatic juice, which is made in the
172
LIFE PROCESSES OF MAN
pancreas, comes into contact with the digested and partly
digested food, causing three different changes. One is to
complete the change of proteins into simpler products ; a
second is to finish converting starches into sugar ; while
the third is to assist the bile (the digestive juice made in
the liver) to digest the fats. The digestion of the food is
practically completed in these three regions of the diges-
tive tube, although digestion continues to some extent
after the food is passed into the large intestine.
The pepsin in the gastric juice is called an enzyme
(C'li'zim: Greek enzymos, fermented) or ferment. There
are three different enzymes in the pancreatic juice, none
in the bile, and one in the saliva. These enzymes are the
chemical bodies which digest food. All plants and animals
digest their food by means of enzymes.
Inorganic foods, such as water, oxygen, and salts, man
takes into his body, making them part of his living pro-
toplasm, or using them in oxidation. There is a large
amount of water in man, enough to make up nearly two-
thirds the total weight of his body. AH of his food con-
tains water.
/
STUDENT REPORT
Where the Food is Digested
In the
Cell
In the
Leaf
Primitive
Digestive
Tube
Stomach
Mouth
Digested
by
Enzymes
Paramecium .
Hydra . . .
Frog ....
Man, etc. . .
Bean ....
Yeast ....
Teacher may explain yeast and bean to help out the comparison.
ABSORPTION OF FOOD L73
Oxygen is breathed in from the air, and the various Baits,
such as common salt, sodium chloride (so'di-um kld'rid, or
rid), calcium (kal'si-um), magnesium (lnag-nf-'/.hi-um, or
-shi-),jP0ta$8iM??i(po-tas'si-um), and phosphorus (fos'fBr-US )
are taken in with our food. They are useful to the body.
A small amount of iron is also contained in food and water
and becomes a part of the red blood cells.
LABORATORY STUDY
Study food and food tests. Artificial gastric juice is easily prepared
"by taking | gram of pepsin, Taff cc. of strong hydrochloric (hi-drft-klo'-
rik) acid and adding 50 cc. of water. Take white of egg that has been
cooked and subject it, in a test tube, to the above mixture. A variety of
tests should be made, with and without heat (100 F.) with and without
the acid. Pancreatic juice is made by uniting 15 grains sodium (so'dl-fim)
carbonate (kar'bon-at), 5 grams pancreatin (pan'kiv-a-tin), and 100 cc.
water. The action of this fluid may be tested as above on the fata, as
■olive oil ; on starch, as flour ; and on proteins, as raw lean meat or milk.
Also examine several of the common articles of food to determine to what
•class of foodstuffs they belong.
147. Absorption of Food. — The absorption of food in man
.and animals is the process of taking the digested foods
from the alimentary canal into the blood. Practically no
food is absorbed in the mouth or esophagus, and but little
in the stomach.
The absorption of food from the intestinal canal is
done by small folds in the lining of the small intestine.
To the naked eye, these folds appear as a covering of
minute hairs, called villi (villi). Their structure is shown
in Figure 189.
The process of osmosis, which has been so frequently
referred to in Part I, is the chief factor in the passing of
the food into the blood vessels. This process is assisted by
the action of the livinsr cells in a manner not well under-
stood.
174
LIFE PROCESSES OF MAN
The digested proteins and sugars pass directly into blood
vessels which lead to the liver. In the liver, these blood
vessels unite to form the portal (por'tal) vein, which is
divided into minute branches that distribute the blood to
the cells of the liver. As the blood thus passes among the
liver cells, the larger part of the sugar is changed into
glycogen (gli'ko-jen), an animal starch, and stored tempo-
rarily in the liver cells. This stored-up starch is given
out gradually and changed
urn
/esse!
lph or
vessels
Wall
\of
Irtres+ine
back into sugar, which re-
sults in keeping a uniform
amount of sugar in the
blood.
The fats pass into certain
distinct vessels, lacteah (lak'-
te-als), which in turn open
into larger ones. Eventu-
ally these vessels unite to
form a large duct — the
thoracic — which empties into
one of the veins near the
heart. The food is now in
the blood stream and is
carried to the individual
cells of the body. Each
cell takes the kind of food which it needs and bv a series
of changes, as yet only partly known, makes the food
into living protoplasm.
The indigestible part of the food is not absorbed, but
continues to move through the small intestine into the
large intestine, and on through the rectum. During this
progress much moisture is absorbed, especially in the large
intestine, which leaves the " undissolved food " harder
and harder. The regular removal of the unused part of
Figure 189. — Diagram of Villus.
ABSORPTION OF FOOD
L75
the food, faeces (fe'sez), is of much importance in main-
taining health, because the bacteria living in the digestive
tract cause the waste material to decay and fche poisonous
substances thus formed are injurious when absorbed into
the blood.
Foods normally remain in the stomach from one to five
hours, and in the small intestine about four hours; while
they may be from six to
twenty-four hours in
passing through the
large intestine.
We become hungry
each day and feel re-
lieved only after eating.
A person frequently eats
a large meal because of
an extra amount of work
that is to follow. But
is he helped to do the
extra work ? Probably
not, for the strength to
do the work of to-day
comes from the food eaten yesterday, or possibly the day
before yesterday. The food, even after digestion is com-
pleted, must pass through many changes before it is built
up into protoplasm. The actual building of the food into
protoplasm is the process for which the word nourishment
is used, and it should not be confused with absorption.
Water.
Figure 190. — Home-made Apparatus
to show Osmosis.
Food as
purchased
contains
Edible portion
e.g., flesh of meat, yolk and
white of eggs, wheat, flour, etc
Nutrients
Protein.
Fata
( Sarbohydrafe 9.
Mineral mat;
Refuse
e.g., bones, entrails, shells, brain, etc.
176 LIFE PROCESSES OF MAN
Alcohol is made up of carbon, hydrogen, and oxygen.
All proteids contain nitrogen in addition to these three.
Because alcohol contains no nitrogen, it cannot be used as
a food to build up tissue.
All serve as
fuel to yield
energy in the
form of heat
and muscular
power.
USES OF NUTRIENTS IN THE BODY
Protein Forms tissue
e.g., white (albumen) of eggs,
curd, casein (ka'se-m) of milk, lean
meat, gluten of wheat, etc.
Fats Are stored as fat
e.g., fat of meat, butter, olive
oil, oils of corn and wheat, etc.
Carbohydrates Are transformed into fat
e.g., sugar, starch, etc.
Mineral matter (ash) Shares in forming boner
e.g., phosphates of lime, assists in digestion, etc.
potash, soda, etc.
Comparative amount of food required for persons of
various ages and conditions, taking as the unit, the amount
of food required by a man at moderately active muscular
work :
Man at hard muscular work requires 1.2 the amount of food of a man
at moderately active muscular work.
Man with light muscular work or boy 15-16 years old requires 0.9.
Man at sedentary occupation, woman at moderately active work, boy
13-15, or girl 15-16 years old requires 0.8.
Woman at light work, boy 12, or girl 13-14 years old requires 0.7.
Boy 10-11 or girl 10-12 years old requires 0.6.
Child 6-9 years requires 0.5.
Child 2-5 years old requires 0.4.
Child under 2 years old requires 0.3.
Heat is a form of energy and one of the reasons for
taking food is to keep up the supply of this energy.
The more work a person does the more energy he uses,
but even a resting body uses some energy, 'for the heart
beats and the muscles of the chest move. The amount of
PREPARATION OF FOOD 177
this form of energy a person uses is measured by a unit
of heat named the calorie (kal'6-ri). A calorie represents
the amount of heat required to raise the temperature of
a pint of water about four degrees Fahrenheit. A man
in rising from a chair, walking eight feet, and returning
uses about one calorie.
Pecuniary Value of Food. — The table on page 178 from
the government bulletin helps to give students an appre-
ciation of the relative cost and value of the more common
foods.
148. The Preparation of Foods. — Some foods, such as
milk, fruit, and nuts, may be eaten without being cooked.
but most of our food has to undergo this process before it
is suitable for eating. As no two kinds of vegetables or
meat are best cooked in exactly the same way, attention
should be given to the preparation of food for the table.
Successful cooking accomplishes four ends. (1) Changes
are brought about to make the food more digestible, such
as softening or dissolving it. (2) The nutritious parts
are carefully saved. (3) Certain amounts of the three
classes of foodstuffs are selected in order that all the
chemical elements which the body needs may be supplied.
This is known as a "balanced ration." (4) The food
is made attractive in appearance and taste, "good to
eat."
Every woman who wishes to have a happy, healthy
family should make a serious study of cooking. Many of
the facts about the nutritive elements which foods contain,
and the many changes which they undergo in cooking
are found out by chemists who study them in laboratories.
It is not necessary for all of us to know all these facts.
but a good cook follows the rules and recipes which have
been made as a result of scientific laboratory studies.
To illustrate how much is involved in cooking, let us
178
LIFE PROCESSES OF MAN
Comparative Cost of Digestible Nutrients and Energy in Dif-
ferent Fooi> Materials at Average Prices1
It is estimated thai a man at light to moderate muscular work requires about 0.23 pound oi
protein and 3,050 calories of energy per day.
a
y.
p
o
Ph
C4
Amounts for 10 Cents
KlM> OF Material
© s
Weight
i) Ma-
z
■n
S
>
H P
— z
\ \
z ~
Z <
Total
of Foe
TERIAL
H
O
<
C <
< >
w —
o
M
W
r, nts
Dollars
Cents
Pou nds
Pounds
Powids
Pounds
Calories
25
1.60
25
0.40
0.06
0.06
—
410
1(5
.87
18
.63
.11
.08
—
:.oo
Beef, shoulder clod . . .
12
. i.»
17
.83
.13
.OS
—
595
Beef, stew meat
5
.35
7
2
.29
.23
—
1,530
Beef, dried, chipped . . .
25
.98
32
.40
.10
.03
—
315
Mutton chops, l<»iii ....
16
1.22
11
.03
.08
.17
—
890
20
1.37
22
.50
.07
.07
—
445
12
.92
10
.S3
.11
.19
—
1,035
Pork, Bmoked ham . . .
22
1.60
13
.45
.06
.14
—
735
12
6.67
3
.S3
.02
.OS
—
2,950
< lodfish, dressed, fresh . .
10
.93
46
1
.11
—
—
220
Halibut, fresh
18
1.22
38
.56
.08
.02
—
265
i
.45
22
1.43
.22
.01
—
465
Mackerel, salt, dressed . .
10
.74
9
1
.13
.20
—
1,135
Salmon, canned
12
.57
13
.83
.IS
.10
—
760
( >\ sters, 35 1 per qt. . . .
18
3.10
80
.56
.03
.01
.02
125
Lobster, canned
IS
1.02
46
.56
.10
.01
—
225
30
30.00
9
.33
—
.27
— ■
1,125
Eggs, 86^ per doz
24
16
2.09
.64
39
8
.42
.63
.05
.16
.04
.20
.02
260
1,185
Milk. T c per <(t
3A
1.09
11
2.S5
.09
.11
.14
s>5
3
.31
••>
3.33
.32
.03
2.45
5,440
Corn meal, granular . .
•-'A
.32
2
4
.31
.07
2.96
6,540
Wheat breakfast food . . .
T§
.73
4
1.33
.13
.02
.9S
2,235
< >at breakfast food ....
>i
.53
4
1 33
.19
.09
.86
2,395
4
.29
2
2.50
.34
.16
1.66
4,500
8
1.18
5
1.25
.08
.97
2,025
Wheal bread
5
.04
4
2
.16
.02
1.04
2,400
5
.65
4
2
.15
.01
1.04
2,340
Beans, white dried . . .
5
.29
3
2
.35
.03
1.16
3,040
2*
2.0S
22
4
.05
.01
.IS
460
6.65
77
2
.02
—
.05
130
10
4.21
23
1
.02
.01
.18
430
Potatoes, 60 p per bu. . . .
1
.67
3
10
.15
.01
1.40
2,950
1
1.33
8
10
.08
.01
.54
1,200
U
5 00
8
6.67
.02
.02
.65
1,270
T
10.00
27
1.43
01
.01
.IS
370
6
12.00
4ti
1.67
.01
—
.13
250
7
8.75
47
1.43
.01
.01
.09
215
G
—
3
1.07
—
—
1.67
2,920
1 Principles of Nutrition and Nutritive Value of Food, W. C. Atwater, Farmers' Bulletin
No. 1 I-.'.
*The cost of 1 pound of protein means the cost of enough of the given material to furnish
1 pound of protein, without regard to the amounts of the other nutrients present. Like-
wi-e the cost of energy means the cost of enough material to furnish 1,000 calories, without
reference to the kind> and proportions of nutrients in which the energy is supplied. These
estimates of t he cost of protein and energy are thus incorrect in that neither gives credit for
the value of the other.
PREPARATION OF FOOD 179
see what it means to produce a loaf of wholesome bread.
Flour contains much starch, some sugar, some mineral
substances known as phosphates, a large quantity of
gluten (a protein), and some bacteria (tiny plant-, see
Chapter XXIV) which may or may not be of value in
making bread. When water is added to the flour, it
becomes tough and sticky, this being a characteristic
of gluten, and the most important one, so far as tin-
making of bread is concerned. A small bit of yeast (a
small plant, see Chapter XXIV) is added to the water
used in making bread, and the dough is placed where it
will be neither too hot nor too cold (70°-80° F.).
The yeast begins to grow rapidly, feeding on the
proteins of the flour, and as the yeast grows, it acts od
the sugar. A substance called zymase (zim'as), secret ed
by the yeast plant, breaks the sugar up into carbon
dioxide, alcohol, and a small quantity of glycerin. The
gas tries to escape, but is held in by the sticky dough. If
the yeast plant is well distributed, the gas collects in
many small bubbles, and the loaf is fine-grained. The
alcohol keeps other plants from growing there, and also
helps to soften the gluten.
When the loaf is put into the oven, the heat kills the
yeast plant, drives off the carbon dioxide, and causes the
alcohol to evaporate. The heat changes the gluten into
a substance more easily digested and of a more pleasant
taste. In "salt rising' bread bacteria from the air,
instead of yeast cells, form the gas which makes the
bread light. When a batch of bread "sours," it is
usually because harmful bacteria get into the dough ami
grow more rapidly than the yeast plants. Sometimes
other kinds of yeasts than the helpful ones employed in
bread-making accidentally get into the batch of bread and
it spoils as a result.
180 LIFE PROCESSES OF MAN
149. Adulteration of Foods. — Foods are adulterated either
by subtracting some of the nutritious parts and substitut-
ing less valuable parts, or by adding materials which can-
not act as a food.
The food formerly subject to the most adulteration was
milk. This adulteration was done by adding water to
make the milk go farther when being measured out, and
adding formalin (for'ma-lin) to make it keep sweet.
For a time many of the cereals were adulterated with
sawdust, peanut shucks, or bran. Many of the special
foods put up in packages used to be adulterated, and it
would require a long description to enumerate all that
have been found unsatisfactory for food by the Depart-
ment of Agriculture.
Pure Food Laivs. — Congress in 1906 passed what is
known as the Pure Food and Drug Law. This law
requires manufacturers of food and medicine to state on
the label what is in each package or bottle. This enables
one to know just what. he is buying.
150. Indigestion. — Few children that have an oppor-
tunity to romp and play out-of-doors and have plenty of
simple and plain food ever experience any ill feeling in
the digestive canal. However, as children grow older,
exercise less, and eat richer food, they may suffer much
inconvenience from indigestion.
Indigestion is a condition which rarely extends to all
parts of the digestive canal; it is located either in the
stomach or in the small intestine. This may indicate that
certain kinds of food are not properly digested. Indiges-
tion may be caused by eating the wrong kinds of foods
or by overloading the stomach. If the food is chewed
thoroughly, the appetite is usually a safe guide as to the
amount needed by the body. Moreover, food thoroughly
chewed is more easily acted upon by the digestive fluids.
INDIGESTION 181
To some people certain foods are indigestible at all
times, while other foods are indigestible only at special
times. We should learn to understand our bodies in this
particular. Some of the causes of indigestion are: lack of
sufficient regular exercise, too much rich food, and the
failure to drink enough water.
Students and professional men use their brains more
than their muscles, but they require protein to repair
nerve waste just as laborers require proteins to feed
their tired muscles. Unless students and professional men
exercise their muscles, they do not feel vigorous and eager
for their work. On the other hand, unless the laboring
men exercise their brains, they do not do their work as
well as they might. The amount of exercise required
varies with the individual. The best way to prevent in-
digestion is to have regular habits of eating and exercising.
There are in the market many tablets and remedies for
indigestion, which may, for example, contain pepsin and
pancreatin. Now we know that these substances when
found in the pancreatic fluid act in an alkaline medium.
As these tablets must first pass into the stomach, which is
an acid medium, the action of the pancreatin is probably
destroyed long before the remedy reaches the intestine
where it would naturally act. This means that such
tablets are largely useless and is one of the reasons
why many doctors believe that digestive tablets are doing
more to cause indigestion than they do to help it. There
are only a few commercial tablets made which act on the
undigested foods of the intestine. No medicine, in fact,
can give permanent relief to indigestion. Predigested
foods, a recent attempt to relieve indigestion, serve a
useful purpose in cases of sickness, but in our regular
life, should be used sparingly because they do not give the
digestive organs the proper amount of work to do.
182 LIFE PROCESSES OF MAN
151. Effect of Alcohol on Digestion. — Alcohol taken into
the digestive tube is closely related to the question of in-
digestion. The lining (mucous membrane) of the stomach
and intestine is delicate and tender, and contains thousands
of cells which secrete the gastric juice, and many more
thousands that help to digest the food. When alcohol
comes in contact with these delicate cells, it prevents them
from doing their normal work. The result is that food is
not properly digested.
Indigestion disguised by alcohol *but not cured. — It is a
serious error to regard alcohol as a genuine remedy for
indigestion or abdominal pain. It is true the sense of
pain is sometimes abolished by alcohol, and as a result of
this many a man believes that alcohol aids his digestion,
whereas it merely exerts a numbing effect on the stomach
nerves, and his indigestion is disguised rather than removed.
In fact, instead of being cured the mischief is increased
since digestion is retarded. Some digestive medicines
contain enough alcohol to be injurious. Alcoholic drinks
taken with meals make the food hard to digest because the
alcohol makes the food tough.
SUMMARY
Man is able to live in all climates and localities on the
earth. No plant or other animal can do this. Man con-
trols his surroundings. Plants and animals are controlled
by their surroundings. Like other animals, man passes
tli rough the periods of growth known as youth, maturity,
and old age.
Man has a definite set of digestive organs that are more
highly developed than those of any other animal. These
digestive organs prepare proteins, carbohydrates, and fats
so that they pass into the blood. The blood is forced
QUESTIONS 183
by the heart through definite blood vessels. The study of
food is important because we require food in order t<> Live.
The cost of food and the amount needed are problems that
science is helping to solve.
QUESTIONS
How does man differ from other animals in regard to the places where
he lives ? Why ? What do man and other animals require in order to
grow? Name the kinds of foods. What is the value of protein? <>t
carbohydrates ? What does cooking do to foods ? Why is this important '.'
What is digestion ? What is indigestion? Absorption? How are the
cells of the body fed ?
CHAPTER XVI
SKELETON AND MUSCLES
152. Skeleton and Muscles. — Muscles which serve to
move the body cover and protect the skeleton of man. The
more delicate organs of the body are protected further
— the heart and lungs by the ribs, and the brain by the
cranium. The skeleton
nasal bones
clavicle (collarbone!
shoulder blode
nu rntrus
vCrani u m
• V-j-Ma'ar (cheek) bone
-superior maxillary bones
■ mferior
and muscles of man are
similar to the correspond-
ing parts in the frog and
the dog. Certain tech-
nical differences are
noted by anatomists, but
in general plan or struc-
ture and in their func-
tions, the skeleton and
muscles are alike in all
the higher animals.
153. The Skeleton. —
Unlike the rest of the
body the skeleton proper
is hard. It consists of
bone and a compara-
tively soft substance
known as cartilage, or gristle. There are cells in the
bones just as there are cells in the liver, the muscles, and
in the nervous system. So, like the other parts of the
184
JV— phalanges
Figure 191. — Skeleton.
THE SKELETON
IS")
Figure 193. - - Dia-
gram of Bone
Structure.
Figure 192.
mlcrophotograph of
Bone.
<©
«w ^>
<5D
<JS
s
®
Compare Figure 193.
Figure 194. — Car-
tilage.
body, the bones grow because the individual cells are
supplied with food from the blood.
Cartilage occurs near the ends of the bones, in the ear,
and in the nose. It is especially prominent in the wrists
and ankles of children. Therefore children should not
be lifted by their hands nor allowed to stand until a
Figure 195. — X-ray of a Normal and a Broken Elbow.
186
SKELETON AND MUSCLES
certain amount of bone has taken the place of this soft
cartilage.
When the bone of a limb is broken the physician sets it,
Le. places the broken ends together, and puts splints on
the limb to keep the parts from slipping until the new bone
has formed and hardened.
The joints of the bones of the arms and legs allow move-
ments in many directions. The tearing or stretching of
Figure 196. — X-ray of
Hand of Child.
Figure 197. — X-ray of Hand of Adult.
the structures which hold the bones together at the joints
is called a sprain. The joints in the spinal column allow
only a limited movement, while the joints in the cranium
are immovable and some of its bones gradually grow
together.
The erect position of man gives to his skeleton important
characteristics which the skeletons of other animals do
THE XKELKTOS
is?
Figure 198.
Broken Femur.
Figure 199.
Same Bone Ten Weeks Later.
Notice the large "callus" of newly forming bone. An illustration of
a poorly set bone. The broken ends of the bone should match. (Potter.)
not possess. Among these may be mentioned the curves
in the spinal column, the large hip bones, and the heel and
arch of the foot.
STUDENT REPORT
Make a report on the skeletal structures of animals as follows :
External
Parauioeeium
Crayfish . .
Clam .
Frog . .
Man, etc. . .
Absent
JOIN! ED
\. 1 1
.i.n s 1 1 n
HOENl
I '- ■ \ -.
Internal
188
SKELETON AND MUSCLES
LABORATORY STUDY
Study the skeleton, and examine long, flat, and irregular bones. How is
the bone modified to do its work ?
154. Muscles. — The muscles are the lean parts of the
flesh of animals and are usually dark in color. Birds are
an exception, for their breast meat
is generally white. Muscles are of
two kinds : voluntary (governed by
the will), such as those which we
use in walking, or in moving the
arms ; involuntary, such as those
which move the food along the
digestive tract or assist in breathing.
The voluntary muscles consist of
many long muscle cells (fibers)
bound together into a distinct
bundle. Usually the muscle bundle
is attached at each end to the bones.
A single muscle moves the arm in
one direction only, and in order to
lift the arm from the desk to the
head, for instance,
several muscles
must act together.
The cells of the
involuntary mus-
cles are unlike the
cells of the volun-
tary muscles. In-
voluntary muscle cells occur in la}rers
in the walls of the digestive tube, blood
vessels, the bladder, and the like, and
they are not under the control of the
will.
Figure 200. — Muscles
of Upper Leg.
Note how they are ar-
ranged in bundles.
Figure 201. — Vol-
untary Muscle
Cells.
Showing how the
cells are bound to-
gether with connec-
tive tissue. At the
end of the muscle,
the cells of the con-
nective tissue form
the tendon.
THE SKIN
IS!)
Figure 202.
- Involuntary Muscle
Cells.
The muscular tissue of the heart has characteristics of
both the voluntary and involuntary muscles, so that it
may almost be said to
belong in a special class.
155. Skin. — The skin
covers and protects the
voluntary muscles, regu-
lates the body tempera-
ture, gives off waste matter, and acts as a general sense
organ. The outer layer of
skin is called the epidermis,
and is chiefly composed of
dead cells. These outer cells
are constantly breaking off, a
process which is most apparent
in the case of sunburn. What-
ever pigment, or coloring mat-
ter, there is in our skin is located in the inner cells of
Figure 203. — Heart Muscle
Cells.
$BS!
,-. - -
Milk .
Figure 204. — Various Forms of Cells in Human Body.
a. side and top view of flat epithelium : b, c, columnar epithelium
d, e, ciliated epithelium. How do these cells differ from the muscle
cells in Figures 201-203?
190
SKELETON AND MUSCLES
Epidermis
lerve
apilla
pap
the epidermis. The amount and kinds of pigment deter-
mine whether a person is of light or dark complexion,
white, black, or yellow. These inner cells are constantly
crowing new cells to replace the cells which scale off.
The nails and the hair arise in the outer layer of the
skin. Other structures which arise in the same way are
the scales of fishes and
snakes, the hoofs and
horns of cattle, and the
feathers of birds.
The inner layer of the
skin is the dermis, and
contains blood vessels,
nerves, connective tissue,
the sweat glands, and
sense organs of touch. It
is estimated that there
are over two million sweat
glands in the skin of a
man. Their work is to
eliminate waste sub-
stances from the blood and to keep the body temperature
normal (98.4° F.) by regulating the amount of perspira-
tion excreted. The amount of perspiration is influenced
both by the temperature of the body and of the air. The
evaporation of perspiration keeps the body at the normal
temperature.
SUMMARY
Man has a skeleton covered by muscles and skin. The
bones grow and are fed just like the muscles. This is
proved when the broken bone heals. The muscles are
the flesh covered by the skin. The muscles are both
voluntary and involuntary. The skin is made up of
Dermis
Nulnlive
paoilla
Sweai &land
Nerve
ood vessels
Figure 205. — Diagram of Skin.
QUESTIONS 191
several layers of cells. 'Nails and the hair grow from the
outer layers. The sense of touch is in the skin.
QUESTIONS
How does the skeleton of man compare with the skeleton of the cray-
fish? How do bones grow? Why do they grow? When is there the
most cartilage in our skeletons ? How many kinds of muscle are there?
What is the work of each ? What is the work of the skin ? Of what is
the skin composed ?
CHAPTER XVII
RESPIRATION, BLOOD, AND EXCRETION
156. Respiration is the life process in which oxygen is
used in, and carbon dioxide eliminated from, the cells of
the bodies of plants and animals. All animals carry on
respiration, and in all the process is alike, although the
various animals use different structures to secure the inter-
change of oxygen and carbon dioxide. The hydra and
earthworm use the entire surface of the body in this
process ; the fish has special organs, the gills, while the
frog and man have lungs.
Student Report on Respiration
Get Oxygen
Get Kid of
Carbon Dioxide
Breathe Through
Water
Air
Water
Air
Skin
Gill
Lung
Air
tubes
Leaves
Amoeba
Crayfish
Fly
Clam
Toad
Bird
Man
Bean
Yeast
In order to help comparison the teacher may explain about the plant.
Organs of Respiration in Man. — Air enters the nose
and passes into the windpipe or trachea (tra/ke-a). The
192
ORGANS OF RESPIRATION
VXi
opening into the windpipe is covered by the epiglottis
(Greek, epi, upon; glotta, tongue), which is raised dur-
ing breathing and closed when food is swallowed. The
windpipe divides into two branches, one entering each
lung. Each branch is called a bronchus. The windpipe
and bronchi are the air passages which cany air to the
lungs. These passages are kept open by numerous stiff
cartilage rings, which, in the trachea, are not entirely
complete on the side of the
esophagus, and in the smaller
tubes even less so.
On entering the lung each
bronchus divides into branches
which in turn branch out again
and again, until the entire lung
is penetrated in all its parts by
these passages. Finally each
branch ends in a small pouch-
like sac called an air cell. The
walls of the air cells are thin,
and the cells themselves are
surrounded by minute branches
of the blood vessels. It is esti-
mated that the highly folded condition of the walls of the
bronchi make a surface larger than the entire surface of
the body. All these thin walls of the lungs and blood
vessels are adapted to the passage of oxygen into tin-
blood.
The lungs of man, then, consist of two large bronchial
air tubes, many brandies of the bronchi, air cells, blood
vessels, and a few nerves, all bound up into two definite
bodies (Figure 206).
The voice box or larynx (la r' inks') is found just below
the opening into the windpipe and is called " Adam's
Figure 206. — Lungs and
Heart.
Note the branches of the
bronchus and blood vessels on
the right side.
194 RESPIRATION, BLOOD, AND EXCRETION
apple." The larynx is formed by several large pieces of
cartilage lined with a mucous membrane. On the inside
ical cords
trachea
During Respiration During Phonafion
Figure 207. — Voice Box or Larynx.
of the larynx project two folds of elastic tissue which are
called the vocal cords.
157. Breathing. — The lungs are elastic and can be
squeezed like a sponge. Inspiration is the term applied
to the taking of air into the lungs, and expiration to the
forcing out of air. When air is drawn into the lungs,
the chest expands, and the diaphragm (Figure 208), the
horizontal muscle which divides the lung cavity from the
abdomen, is drawn down. Thus the chest cavity is en-
larged and air is sucked into the lungs. In expiration
the air passes out gently.
When we breathe naturally, only a small part of the
air in the lungs is exchanged at each inspiration and ex-
piration, but by breathing deeply a few times we can
remove the larger part of the air from the lungs and re-
place it with fresh air.
The natural rate of breathing is about eighteen times a
minute, but the rate is higher in persons with a small lung
capacity. Exercise increases the rate of breathing. Ex-
BREATHING
L95
plain why exercise out-of-doors is better for us than that
taken indoors.
All the air passages are lined with cells bearing numer-
ous cilia (Figure 204), and these cilia are constantly in
motion. Their work is to carry toward the mouth the
particles of dust and other
foreign materials brought in
by the air. This foreign matter
is removed when we cough or
clear our throats. Explain why
clean air is better for us than
dirty air.
The air that enters the lungs
is rich in oxygen and there is
some oxygen in the air which is
expired. But the proportion of
carbon dioxide is greater in
the expired air of plants and
all animals.
Ventilation. — Associated with
the question of breathing is the
problem of supplying our homes
with fresh, clean air. Every
one feels better after a walk in the open air. How to
have plenty of fresh air in our rooms is a diilieiilt problem.
One of the difficulties is to get the air down to the breath-
ing line and not stir up the dust on the floor. Figures
209 and 210 show the best plans for ventilating a room.
They are adapted to the two common methods of heating,
hot air and steam or hot water. They show the coins.' I aken
by the currents of fresh air entering the room at night with
the window open, and in the daytime with it shut.
Exercise. — Even if the home is furnished with fresh
air, we should observe good habits of breathing. When
a. -Oesophagus
b. -Diaphragm
Figure 208. — Diagram of
the Diaphragm.
Note the position at the bot-
tom of the thorax.
196 RESPIRATION, BLOOD, AND EXCRETION
POOM AT A//6//7"
/vowecr HSJrwG.
we walk out-of-doors, we should take plenty of fresh air
into our lungs in a series of deep breaths. All young
people should take exercise in the open air, because such
exercise develops all the organs and makes them strong.
Thus the whole body becomes more robust and better able
to withstand disease and
to do its work.
Suffocation. — When
the body is deprived of
a sufficient supply of
oxygen, suffocation re-
sults. This is what
happens in drowning or
when the windpipe be-
comes closed.
In many cases a per-
son who is suffocating
may be saved through
artificial respiration.
This is the name given
to a series of movements
which are used to restore
natural breathing. The
simplest method is to
place the patient on his
back, with the head
lower than the hips.
Then raise the arms upward and outward until they come
together above the head. This movement enlarges the
chest cavity and helps to draw air into the lungs. The
air is forced out of the lungs by bringing the arms back to
the side of the body and pressing gently against the
sides of the chest. This series of movements should be
repeated gently every few seconds, and may have to
f '-^^•^^^=^gr3Kgggsj5^^"^a^.^ va 'x--:'- ■;'- -^
Room /HD4vr//v£
/A/PW£Cr H£jr/A/G.
Figure 209. — Hot-air Heating.
By Earl Hallenbeck.
BLOOD
197
#OOM AT A//GWT
£>//?£ CT HEJT/HG
be continued for hours before natural breathing is
restored.
Diseases of the Respiratory Tract. — The most common
of these diseases is a cold located in the nose and throat.
The nasal passages be-
come clogged with
mucus which contains
many germs. These
germs are widely distrib-
uted in sneezing.
Diphtheria is a germ
disease which is located
in the throat and nose.
For many years diph-
theria was one of the
most deadly of our dis-
eases, but through the
use of the diphtheria
antitoxin the danger has
been greatly reduced.
Tuberculosis of the
throat and lungs is a
widely distributed dis-
ease which causes many
deaths each year. See
page 235.
158. Blood. — The blood is the fluid which circulates
through the heart, arteries, and veins, supplying nutritive
material to all parts of the body. Blood is made up of a
fluid (plasma) which contains cells or corpuscles ( Latin,
corpuseulum, little body). The blood cells or corpuscles
are of two kinds, red and white.
The red corpuscles are colored with a substance called
haemoglobin (he-mo-glo'bin: (iivek, haima, blood: globus,
BR£ATHIN6 LIN£
■
- OUT
i-
-
Room //vD^yr//V£
£)/&£ c T H£A T/HG
Figure 210. — Steam Heating.
By Earl Hallenbeck.
198 RESPIRATION, BLOOD, AND EXCRETION
Figure 211. — Micro-
photograph of Blood
of Frog.
ball). When a few of these corpuscles are examined
through a microscope, they appear yellowish instead of
red ; but when a large number of
them are seen in a mass, the red
color is apparent. When the red
cells are first formed, they have a
nucleus which gradually disappears.
As a result, the mature red corpus-
cles, unlike all the other cells we
have studied thus far, have no
nucleus. Red corpuscles are about
3<>Vo °^ an incn iR diameter and
T2T0 o °^ an ^ncn thick.
The red corpuscles carry oxygen from the lungs to
the cells of the body. This oxygen unites with the
haemoglobin. By osmosis the oxygen passes from the
blood to the body cells which are deficient in oxygen.
These cells take the oxygen and use it in the process of
oxidation, which goes on
continuously in every
living cell. A good
supply of red blood
corpuscles is, therefore,
necessary, if the cells of
the body are to have a Figure 212.
sufficient supply of OXy- As the blood flows through the capil-
2"en. The feeding" of ^aries which are found in all voluntary
. ,, . , . muscles, for example, oxygen and other
the cells with oxygen is food products are given off to the muscle
One part of respiration. cells, and carbon dioxide and other
At the same time that waste substances Pass off from these
same muscle cells into the capillaries
oxygen is received from on the way int0 the veins.
the blood by the body
cells, carbon dioxide is given off. Again osmosis explains
the method of this transfer. Most of the carbon dioxide is
BLOOD
199
Figure 213. — Organs of Circulation.
Veins, black ; arteries, with transverse lines. Left side of figure shows
superficial vessels, while right side shows deeper vessels.
200 RESPIRATION, BLOOD, AND EXCRETION
carried by the plasma, although some of it unites with the
haemoglobin.
White blood corpuscles are much like the amoeba in
that they are colorless and can change their form. They
move about in the body and often leave the blood vessels
and collect at one place to aid the body in destroying
disease germs.
The blood plasma is straw-colored and varies in compo-
sition from day to day, and hour to hour. It contains the
foods on their way to the cells and waste products on their
way to the kidneys, lungs, or skin.
The volume of blood in the average person is about six
quarts.
When exposed to the air, blood forms a clot, because of
the presence of a substance (fibrinogen) which produces
fibers that hold the red and white corpuscles.
Student Report on Blood
Name of Animals
©
N
X
o
p-1
o
O
H
O
a
w
«
o
Hi
o
Color in
Plasma
CO
C P
o 5
o o
o
*3
►4
W
m
H
>— <
w
o
03
159. Heart and Blood Vessels. — The blood is carried
from the heart to all the cells of the bodv and back to the
heart again and again. The heart serves as a pump to
force the blood along. The heart is about the size of
the fist and has strong muscular walls. In a healthy
person, it contracts regularly about seventy times a min-
HEART AND BLOOD VESSELS
201
J*>
ute. It is obvious, therefore,
that the work which the heart
does is very great.1
The heart is located in the
thoracic, or chest cavity, a little
to the left side and between the
lungs. It is a cone-shaped organ,
inclosed in a membranous bag"
called pericardium (per-i-car'di-
um : Greek, peri
U around ; cardia,
heart).
The heart is
divided by a wall
into right and left
chambers. A nearly complete cross parti-
tion divides each side into upper chambers,
the auricles, and the lower ones, the ventri-
cles. The opening between an auricle and
a ventricle is guarded by a valve, which is
partly membranous and partly muscular.
The auricles receive blood from the veins,
while the ventricles force blood into the
arteries.
Artery is the name given to the blood vessels which
carry blood from the heart, and vein is the term applied
Figure 214. — Heart.
Figure 215
Diagram
Vein.
of
Showing the
valves.
1 " The work the heart does during the day is about equal to the energy
expended by man in climbing to the top of a mountain 3600 feet high.
Assuming that the man weighs about 150 pounds, this would be equal to
an amount of energy sufficient to lift 00 tons to a height of three feet
The work of the left side is greater than that of the right, since the
former has to drive the blood all over the body, while the latter baa only
to force it to the lungs which are near by. For this reason the muscle
walls of the right ventricle are much thinner than those of the left
ventricle." — Conn and Buddington.
202 RESPIRATION, BLOOD, AND EXCRETION
Figure 216. — Diagram of Capillaries.
The artery breaks up into minute
branches, the capillaries, which in turn
unite to form veins.
to the vessels which return blood to the heart. There is
little structural difference between the veins and arteries
except that the walls of
the arteries are thicker,
and there are no small
valves as in the veins.
As the branches of the
arteries become minute,
the walls become much
thinner, thus allowing
the food and oxygen to pass more easily to the individual
cells. These minute branches are called capillaries
(Latin, capillus, hair). From a cluster of capillaries a
small vein begins which soon connects with a slightly
larger vein, which leads back
to the heart through larger
and larger veins.
The blood follows a regular
course through the body, pass-
ing from the left ventricle into
the aorta, which is the largest
artery in the body. As soon
as the aorta leaves the heart,
smaller arteries branch from it,
and the aorta itself also branches
until the entire body is sup-
plied with blood. The right
ventricle gives off a short
arterv which divides, and a
branch enters each lung. At
the point where an artery
leaves a ventricle, there are three half -moon-shaped valves
which prevent the blood from flowing back into the heart
(Figure 215).
To Brain
To Skin
--To Arm
"-To Lung
To Kidneys^
To Stomach
•To Small
Intestine
:_ ";:To Back
To Large Intestine
-To Leg
Figure 217. — Main Arteries
of Frog.
HEART AND BLOOD VESSELS
21 >3
I 0 I
All to Back
4^;;^ To stomach
-
—
\ To Kid-
' p^-^Jo Reproductive
organs
To L.i
■
The blood which is carried
into the lungs contains a large
amount of carbon dioxide
which gives it a dark color.
In the lungs the carbon dioxide
is given off and oxygen taken
up, so that when this blood is
returned to the left auricle, it
is of a bright red or " arterial "
color.
Every time the heart beats
the blood is forced into the
arteries in waves which can be
felt in the wrist or neck by
placing the finger over an
artery. The wave is called
the pulse. By counting the
number of waves each minute,
the rate at which the heart beats
is determined. When a person
runs or takes violent exercise,
the pulse rate increases. It
is advisable to know what our usual pulse rate is, for
an increased pulse rate is sometimes an indication of
approaching illness.
Lymph. — As the blood flows through the capillaries,
part of the plasma passes through the thin walls into the
spaces between the cells and bathes the cells. This fluid
which escapes from the capillaries is called lymph (llmf).
It is composed of digested food, water, and other sub-
stances. The cells take up the food which they nerd
and cast back into the lymph the wastes which they have
formed in the process of growth and repair. These spaces
between the cells are small and irregular in shape. The
To Legs
Figure 218. — Main Arteries
of Man.
Compare with Figure 217.
204 RESPIRATION, BLOOD, AND EXCRETION
spaces, however, form a sort of mesh, or net, the parts of
which join, forming larger vessels, and finally all the
lymph is collected into two large vessels which open
into veins. Thus there is the lymphatic circulation which
differs from that of the blood in several ways. (1) There
is no special organ for forcing the lymph along, the circula-
tion depending mainly upon the movement of the muscles.
Figure 219. — Superficial Lymphatics of Arm and Hand.
(2) The lymphatic vessels are imperfect in the beginning,
being only irregular spaces. (3) The lymph contains
no red corpuscles and only a few white corpuscles.
Cuts. — Since every part of the body inside the skin is
traversed by blood vessels, we cannot injure any part
without breaking at least some of the blood vessels. A
small cut causes the blood to flow only from capillaries,
and it flows slowly and in small quantities. If a vein is
cut, the blood will be dark in color, and will flow in larger
quantities, but steadily. A severed artery sends out
bright red blood in waves corresponding to the beat of
the heart. To stop the flow of blood from a vein, com-
press the vein beyond the cut ; from an artery compress
the artery between the cut and the heart. In either case
remain quiet to aid the blood to form a clot.
Exercise. — The object of a circulatory system and of a
circulatory fluid is to supply every cell in the body with
HEART AND BLOOD VESSELS 205
food and to carry away the waste. The more active tin-
process of circulation, the more perfectly is this object
accomplished. It is the common experience that the
heart beats more rapidly, the lungs work harder, and the
body becomes warm after a few minutes of vigorous
exercise. These changes have a decidedly beneficial
effect upon building up the body and removing tin-
wastes.
In most kinds of work only one set of muscles is used.
This set gets a full supply of blood, but others get less
than a full supply and so they get too little food and ac-
cumulate too much waste. Every one should, at some time
in the day, take exercise in the open air which will bring
all his muscles into play. If it is enjoyable exercise, tin-
effects upon the mind react favorably uj)on the body.
This is the advantage of such exercises as skating or
baseball. In the winter it often requires real effort to
force oneself to leave a warm room and to go out for ex-
ercise, but if one is properly clothed, cold air has a bracing
effect not obtained at any other time of year.
Fainting. — Fainting is due to an insufficient supply of
blood in the brain. This lack of blood may arise from
several causes, but the most common is some disturbance
of the digestive processes, which causes the heart to beat
too slowly. A fainting person should be placed flat on
his back, if possible, with his head slightly lower than the
rest of his body, and should be given plenty of fresh air.
A dash of cold water in the face, or a bottle of ammonia
held to the nostrils, is often helpful in restoring conscious-
ness.
TJie Effect of Drugs and Alcohol. — "The flow <>f tin-
blood is modified by various drugs, some causing the blood
to flow more rapidly, others more slowly. Coffee cans. -
the heart to beat harder and at the same time causes some
206 RESPIRATION, BLOOD, AND EXCRETION
of the arteries to become smaller. For this reason it is
called a stimulant." —Conn and Buddington.
It has been stated frequently that alcohol increases the
activity of the heart. Careful experiment, however,
shows that not only is the effect not that of a stimulant,
hut that when used in large amounts, it markedly weakens
the action of the heart. If taken only in small amounts,
the heart sometimes shows a slight increase in its rate of
beating, but this occurs only when the brain becomes ex-
cited, and if the person is kept quiet no change in the
heart beat is noticeable. Thus the primary action is on
the brain.
" A second effect of alcohol is more evident. The small
blood vessels in the skin are enlarged. This produces a
flushed skin, a feeling of warmth, and a false feeling of
increased circulation. Its result is to send more blood
through the skin with consequent extra loss of heat. This
action is evidently not due to stimulation, but to the re-
laxation of the muscles, and is thus a decrease of activity
rather than an increase, even though the blood does flow
a little more rapidly through the skin. These facts make
it clear that alcohol cannot be properly called a stimulant
of the circulatory system." — Conn and Buddington.
160. Excretion. — Every animal uses energy in carrying
on its work. During this process a certain amount of
waste substance is produced, which has to be removed
from the body. The skin, kidneys, and lungs are the
chief organs which assist the body in getting rid of this
waste. When any part of the living cells is broken down
in the simple act of living, a waste product results. By
osmosis these waste products enter the blood and are
removed by the lungs, which give off carbon dioxide; by
the sweat glands in the skin; and by the kidneys, which
remove the wastes that contain nitrogen. The sweat
EXCRETION
207
glands and kidneys are usually regarded as the excretory
organs of man. These organs remove from the blood the
wastes which have been excreted by the cells of the body.
The excretion from the living cells is one of tin* funda-
mental life processes of all plants and animals. This form
of excretion should not
be confused with the in-
digestible part of the
food which is not taken
up by the blood and
which passes out through
the large intestine as
fseces.
The kidneys are two
bean-shaped organs lo-
cated in the abdominal
cavity, one on each side
of the "small" of the
back. Each is about
four inches long, two
and a half inches wide,
and half an inch thick.
The color is a dark red.
The kidney is made up of two' layers, the outside or
cortical, and the inside or medullar jf. Each layer is com-
posed of many small tubes (tubules') which open into an
area called the pelvis} the space within the kidney. The
pelvis continues into a duct (ureter), and from each
kidney the ureter passes into the bladder. A small duct
(urethra) connects the bladder with the exterior of the
body.
Each tubule in the kidney is in dose relation with the
Figure 220. — Section of Kidney.
i The word pelvis is also used in referring t«> the hip bones, and it Is better
to call the latter structure the bony pelvis.
208 RESPIRATION, BLOOD, AND EXCRETION
Arterrj
uriniferous
tubule
Figure 221. — Diagram.
Showing relation of artery and
vein to portion of minute kidney
tube (uriniferous tubule).
blood capillaries. At the
place where this close re-
lation takes place, glomeru-
lus (glo-meVu-lus), the
walls of the capillary and
the walls of the kidney are
very thin. Through these
thin walls a large amount
of water filters out of the
blood into the tubes. At
the same time waste ma-
terial which contains nitro-
gen, salts, and other organic
wastes is removed. If these wastes are not removed,
they create toxins which poison the body.
SUMMARY
All living things breathe oxygen which, in the higher
animals, is carried by the blood to the cells of the body.
The parts which man uses in breathing are more highly de-
veloped than in any other animal. Man has a voice box, the
larynx, by means of which he is able to make a wide variety
of sounds. The blood of man is similar to the blood of all
the other vertebrates, although not identical. It consists of
red and white corpuscles which move freely in the plasma.
The blood is confined in the blood vessels through which it
is forced by the heart. Excretion includes the waste
products derived from living protoplasm. The kidneys
and sweat glands remove the liquid wastes from the
blood.
QUESTIONS
Compare the respiration of man, the hydra, and the earthworm. Com-
pare the lungs of man with the gills of a fish. What is blood ? What
is its use ? What is the difference between veins and arteries ? Explain
the work of the kidneys and of the lungs
CHAPTER XVIII
THE NERVOUS SYSTEM OF MAN
161. Parts of the Nervous System. — The nervous system
of man consists of the same general parts as the nervous
system of the frog (See page 118). There is a brain and
spinal cord, from which nerves extend to the special
senses, the muscles, the heart, and the stomach. When
the brain of man is compared with that of the frog, it is
obvious that the cerebrum of man is proportionately larger.
Although some of the other parts of the brain appeal
unlike the corresponding regions in the frog, scientists
tell us that they are really the same.
162. The Nerve Cell. — The nervous system of man con-
sists of many thousands of nerve cells which differ from all
other cells in having more parts and branches (Figures
223, 224, 225). The nerve cells are unlike other evils
in appearance, although they have the usual parts. Ex-
amination shows that the nerve cells have a prominent
nucleus surrounded by cytoplasm, which grows out into a
number of branches called fibers. The shorter branches
divide and form, together with the branches from the
neighboring nerve cells, a mass of tangled fibers. There
is usually one unbranched fiber, perhaps several feet Long,
which ends either in the skin, in some muscle, or in tin-
nervous system. When this long liber readies the muscle
or skin, it divides into several fine branches. All of these
branches which arise from a nerve cell belong to it, and in
this connection the word cell includes all the branches,
the nucleus, and the cytoplasm.
209
210
THE NERVOUS SYSTEM OF MAN
163. The Location of the Nerves. — The nerve fibers
which have the same work to do occupy certain definite
places in the brain
or spinal cord. So
a student of the nerves
can tell the route
which the stimulus
arising from feeling
a pencil must travel
before reaching that
part of the brain where
it is interpreted as a
pencil ; or the route
over which the stimu-
lus arising from tast-
ing candy must pass
before it is known to
be candy. When we
see the pencil or the
candy, the route over
which the sight stimuli
of these two objects
travel is not the same
as that of the feeling
of the pencil or tasting
the candy. The nerve
cells which interpret
the stimulus arising
from feeling the pencil
or from tasting the
candy or seeing the
pencil and the candy
are probably not the same. We may say, therefore,
that the spinal cord and brain are made up of many
Figure 222. — Nervous System of Man.
GROWTH OF THE NERVOUS SYSTEM
211
Figure 223. — Nerve Cells.
special nerve pathways which end in nerve cells thai
interpret stimuli.
The nerves which connect the central nervous system,
that is, brain and spinal
cord, witli all parts of
the body, consist of
many long nerve libers.
Each nerve looks like a
small white thread and
is covered with a thick,
fatty sheath (medullary
sheath). In the living animal, this fatty sheath is white
and the nerve fibers so covered are found to occupy a
certain part of the spinal cord and
brain. Thus, we get the name white
substance. Other of the nerve fibers
and cell bodies are not covered with a
sheath and so have a gray appearance.
Thus we have the term gray substance in
connection witli the nervous system.
164. Growth of the Nervous System. —
The nervous system of man, like all
other parts of the body, lias a definite
beginning and grows in an ordered
manner. Not only is this true in man,
but also in the frog and fish. The
tissue of the embryo, which is to grow
into brain and spinal cord, gradually
changes until the adult parts are formed.
During this early period of growth, the
nerve cells send out processes which
become nerve fibers, so that at birth the
Figure 224. -Nerve nervous system is ready to go to work.
Cells. Indeed, nearly all the nerve cells which
212
THE NERVOUS SYSTEM OF MAN
4
.. ft* <j*
- - •*
the human being is ever
to use are made before
birth. These cells grad-
ually become more active
and the different parts of
the brain work more per-
fectly as we go through
the periods of childhood,
youth, and maturity.
The brain becomes a
more perfect working
organ by making the
brain cells do their
specific work over and
over and over, until each
group of cells can be
relied upon to do a
definite thing.
165. Reflex Action. —
Reflex action is the
simplest form of nervous activity in man. For example,
when the finger is placed on a hot stove and suddenly
i
Figure 225. — Micro-photograph of
Brain.
The nerve cells are black.
,sl<in
ganglion
'sensory
fiber
motor
fiber
%
JVJJ
rTMw*
* 3
> °0 6*
» O Oo
>© © *
»° ? . * ~ • •
%%°
•V.-*.*:"
motor ce
II
muscle
Figure 226. — Diagram to show Reflex Action.
The stimulus comes in contact with the skin and is carried to the
spinal cord. It then passes to the motor cells which carry the order
to the muscle. The same skin stimulus goes to several other parts of
the spinal cord.
REFLEX ACTION 213
withdrawn the following actions take place. The heal
stimulus affects the nerve endings in the finger and that
stimulus is carried to the spinal cord. If this were all that
occurred, the finger would burn, because this stimulus and
the nerve fibers over which it travels have no control over
the muscles. The removal of the linger calls into play an-
other set of nerve cells, — the cells which have their fibers
ending in the hand and arm. All of these changes take
place involuntarily, and the reaction to the stimulus is
known as reflex action. Specific names are used in de-
scribing these several changes ; the nerve fibers which
connect the skin with the spinal cord and brain are
called afferent (affer-ent: Latin, ad, to ; fero, to carry )
fibers because the stimulus always travels toward the
brain.
Their function is sensory, for they carry the stimulus to
the brain. The fibers which connect the muscle with the
brain or spinal cord are the efferent (ef'fer-ent : Latin,
ex, from ; fero, to carry) fibers, because they carry their
message away from the central nervous system. Their
function is motory. In the special instance we are study-
ing, the heat stimulus causes the spinal cord to send a
special message to the muscles of the finger, so that the
latter is removed from the stove.
This is a typical illustration of the simplest way in
which the nervous system works, but in most reflex
actions there are other results. After the finger has been
removed from the hot stove by reflex action, we soon
realize that the skin is burned, the realization oniim;
through the smarting sensation. This second stimulus
has been carried to the brain, and we are now conscious of
the stove, heat, burn, etc. If there were no afferent nerve
fibers, the individual could not experience any pain when
hurt.
214 THE NERVOUS SYSTEM OF MAN
The afferent and efferent nerves, whether in reflex or
in general nervous action, never vary in the work which
they do. The sensory afferent nerves form the only paths
over which our knowledge of the outside world travels to
the brain. The stimuli which cause the different sensa-
tions, such as taste, sight, etc., have their individual paths
and receiving organs. This is indicated by the fact that
no other nerves than those of the ear are ever affected
when we hear.
Reflex Action in the Frog. — The frog, like man, is able
to act in a definite way. If any one approaches a frog
while it is sitting on the edge of a pond, it jumps into
the water, stirs up the mud, and then returns to the shal-
low water near the place where it entered. The frog, in
this case, acts as if it, or its ancestors, had learned that
this is the best way to escape enemies. While this series
of acts is called a habit, it is really a series of reflex acts
which are similar to the reflex action described for man,
and require the same nerve structures.
Reflex Action in the Earthworm. — If a light is flashed
on an earthworm at night, the worm will quickly with-
draw to its burrow, before it can be seized. The earth-
worm has no eyes, but it is able to respond to light and
can tell the difference between night and day. It is
believed that special nerve cells in the skin, which are
connected with the nerve ganglia, help the earthworm to
become aware of the light stimulus.
Reflex Action in Hydra. — Hydra is a minute water
animal which has no definite nervous system, but only
a few nerve cells scattered through the body. As the
hydra waves its arms about in the water, there seems to
be no purpose in its motions. But if a water flea swims
against one of the tentacles, a part or all of the tentacles
at once begin to carry the flea to the mouth of the hydra.
SENSE ORGANS 215
The hydra, then, without a definite nervous system, ran
carry out a definite reflex action.
Reflex action is similar in all animals. In all of these
illustrations, it is necessary for the stimulus to be received
by an afferent nerve, or some structure which can do the
same work, and for the stimulus to be transformed into a
series of purpose-like movements.
166. Sense Organs. — All of the higher animals have
eyes, ears, a nose, and a tongue. Each of these organs
contains nerves specialized to respond to a certain definite
kind of stimulus. The result of this specialization is that
not only are these special sense organs complex: in struc-
ture, but also the region of the brain which receives their
messages. The ear nerve responds to a stimulus of
air-waves of a certain length, and we say we hear a
sound. The eye nerve is stimulated only by light.
Each nerve and the brain cells to which it sends its
messages have become so specialized that practically
only one kind of reaction takes place. For example,
all stimuli acting upon the eye nerves are interpreted
as light.
The skin is a simpler sense organ than the eye or ear.
and tells us of pain and touch and the difference between
heat and cold.
The Eyes. — The eyes of all vertebrates have the parts
arranged in a similar manner. The eyeball is roundish
and is located in the eye sockets of the skull, which are
termed orbits. There is an upper and a lower eyelid, and
the remains of a third eyelid in the corner next to the
nose. The front of the eve is covered by a transparent
membrane, the cornea (kor'ne-a); and the rest of the
eye is surrounded by a tough membrane, the Bclerotic
coat, or the white of the eye. Within the combined
covering of the cornea and sclera are a number of struc-
216
THE NERVOUS SYSTEM OF MAN
tures which take part in receiving and transmitting the
rays of light to the brain.
A cross section of the eye shows two more membranes
in close relation to the sclerotic coat (Figure 227). The
membrane in direct con-
tact on the inside with
the sclerotic layer is the
choroid (ko'roid). The
choroid coat is filled
with blood vessels and
pigment. Through this
layer the food in the
blood is distributed to
the eye. The third
layer or coat is the
retina, which is com-
posed of nerve cells and
which is nearly trans-
parent.
The cornea and these three layers inclose two chambers
which are separated by the lens (Figure 227). In front of
the lens a curtain-like membrane, the iris, partly covers
the lens, except for a round opening in the center which is
called the pupil. The color of the eye, gray, black, blue, or
brown, is due to the presence of pigment in the iris. The
small front chamber is filled with a transparent fluid which
is composed principally of water and is known as the
aqueous (a/kwe-us) humor. The large back chamber is
filled with a thin, transparent, jellylike fluid, the vitreous
(vit're-us) humor.
In order that wTe may see any object, a pencil in our
hand, for example, two general conditions must be present.
The picture (image) of the pencil must be placed on the
retina, and this picture must be carried to the brain by
Figure 227. — Section of Eye.
C, cornea ; C', choroid layer ; /, iris ;
I. C, inner chamber ; 0. C, outer cham-
ber ; L, lens ; 0. N, optic nerve ;
R, retina ; S, sclerotic coat.
e
Figure 228. — How we see the Pencil.
SENSE ORGANS 217
the eye (optic) nerve. When these two conditions bake
place, we see.
As we have learned, the stimulus for the eye is always
light. In physics we learn that the rays of light brave] in
straight lines. This fact explains why we cannot
round a corner. When the rays of light are made to pass
through a glass lens, the rays which pass through the thin
edges of the lens are bent and do not travel to the same place
they would have reached had they not passed through the
lens. In the same way light rays from an object pass
through the lens in our
eyes and are bent. This
results in the image of
the object, the pencil in
this instance, being in-
verted on the retina.
The light rays of the pencil stimulate the nerve cells in
the retina, and this stimulus, after being carried to the
brain, is interpreted to us as a pencil, though we do not
know how stimuli travel on nerves. The inverted image
of the picture on the retina is made to look natural to us
because we are used to seeing everything in inverted imag
Care of the Eyes. — The eyes are our most precious
sense organs, and as such they should receive the best of
care. Certain imperfections in the lens or other parts of
the eye can be helped by the use of glasses. If your «\ ea
annoy you, or if you cannot see objects as clearly as your
schoolmates, have a competent oculist examine and treat
them.
The Ear. — The ear is a sense organ for the reception
of the stimuli which we interpret as sounds. The ear of
man consists of the outer, middle, and inner ear. The
first two carry the stimuli to the third, where the}' are
received by nerve cells and carried to the brain.
218
THE NERVOUS SYSTEM OF MAN
The diagram of the ear (Figure 229) shows the several
parts and their relations. The outer ear leads to the tym-
panic (tim-pan'ik) cavity ; the middle ear is in commu-
nication with the mouth, and the complex inner ear is
partly shown. There is a group of small bones in the
middle ear which conduct the sound vibrations to the
delicate inner ear. The internal ear receives the various
sound waves, and transmits
them to the brain, where they
are explained as sounds.1
Hearing. — Sound waves strike
the ear drum (tympanic mem-
brane), which in turn causes the
small bones in the middle ear to
vibrate. The bones cause the
water in the internal ear to
move, thus stimulating the
nerves of hearing.
The pressure of air on each side of the ear drum is nor-
mally the same. This is due to the entrance into the mid-
dle ear of air from the mouth, through the eustachian
tube (see page 166). This tube is a trifle more than
an inch long. When it becomes closed, partial deafness
results.
Defects in hearing may be caused by blows upon the
ears, by the accumulation of wax in the ears, and by sore
throat. When there is a continued ringing or hissing
sound in the ears, consult a doctor at once.
167. Brain Efficiency. — While the efficiency of the brain
depends upon mental training, in order properly to exer-
cise the many functions of this organ at least three things
Figure 229. — Plan of Ear.
0. E, outer ear ; M. E, middle
ear ; /. E, inner ear ; Eu, eu-
stachian tube.
1 When certain parts of the ear (semicircular canals) are injured, one has
difficulty in standing or in walking erect. This is because the inner ear
serves both as a hearing and a balancing organ.
BRAIN EFFICIENCY
219
SKILL AND ENDURANCE IMPAIRED
BY DRINK
Tests in Target-Shooting in Swedish Army
I. SKILLED TESTS
Thirty shots fired in quick succession
Non-Drinking Days: Average 24 hits oat
of80 Bhots
Drinking Days: Average 8 bits onl of
:5n Shots
■
Alcohol taken equal to amount in P.j to 2
pints of 5 per cent beer, •_'(» to 80 minutes
before shooting, and an equal amount the
night before
II. ENDURANCE TESTS
Non-Drinking Days: 860 Bhots fired be-
fore exhaustion
Drinking Days: 2TS shot- fired before i I
haustion
Alcohol taken 3o minutes before tesl vras
amount contained in about ll/4 pints of
4 per cent beer
are necessary: good food, sufficient sleep, and abstinence
from alcohol and tobacco. We have already discussed the
question of food (page 169).
The amount of sleep which grown people need depends
in part upon the kind and amount of work they do. But
all young people require a large amount of sleep. Chil-
dren from seven to ten years of age need at least twelve
hours of sleep every night,
while youths of high school
age need at least nine hours,
and ten would be better.
At a baseball game, you
have noticed a boy catch a
" fly " when it looked like a
" home run," or how enthu-
siastic the crowd became
when the pitcher struck out
the last man with the bases
full. The nervous system
of both players was efficient
in a critical test.
We all ride on the street
cars or railroads, but do you
know that most of the men
who run the street cars and
trains have to pass an ex-
amination to determine whether they can be trusted to do
their work properly and well ; i.e., whether their nervous
systems will stand the test? Among the questions which
their prospective employers are sure to ask is. M Do you
use alcoholic drinks ? "
In order to judge the success of a piece of work we must
consider the quality and speed with which it is done.
Kraepelin made the following experiment, the results of
Figure 230.
220 THE NERVOUS SYSTEM OF MAN
which show that both these elements in mental work are
influenced by the use of alcohol.
Several men who were allowed to drink no alcohol util-
ized half an hour daily for six days in adding figures.
Their ability to add increased each day. On the seventh
day the work was begun under the influence of alcohol.
In spite of the skill gained in the previous practice, their
accuracy did not increase, but on the contrary began to de-
crease rapidly. On the nineteenth day the use of alcohol
was stopped, and immediately an improvement in the work
manifested itself ; but on the twenty-sixth day, when the
use of alcohol was resumed, a decided decrease in the
power of adding manifested itself.1
It is difficult to estimate how efficient each of us may
become in our life work, but one thing is certain, that if
we use alcohol, we shall lose that perfect control over our
nervous systems, which enabled the two players to be so
efficient in the ball game. It is also equally certain that
if we use alcohol, we shall find fewer men willing to em-
ploy ns in places of responsibility, not only because of our
1 Schiller was wont to say, " Wine never invents anything," and Helmholtz,
one of the greatest observers and thinkers of the nineteenth century, noted in
himself the effect of alcohol in interfering with the highest powers of thought
and conception. At the celebration of his seventieth birthday in Berlin, when
the courts of Europe and the whole scientific world joined to confer numerous
honors upon Helmholtz, he described in the course of a speech the coudition
under which his highest scientific thoughts had matured and come to fruition.
He said :
" Frequently they slyly enter the mind without one's immediately attach-
ing any importance to them ; later some very simple accident or circumstance
may be sufficient to reveal to us, when and under what circumstances they
arose, or they may be present without our even knowing from whence they
came. At other times they come to us suddenly, without any exertion what-
ever, just as an inspiration. As far as my experience is concerned, they
never came to a wearied brain, or at the writing desk. They were especially
inclined to appear to me while indulging in a quiet walk in the sunshine or
over the forest-clad mountains, but the smallest quantity of alcohol seemed to
scare them away."
ALCOHOL, A NARCOTIC
22 1
DRINK impaired SCHOLARSHIP
A Comparison of Abstaining and
Drinking School Children in Vienna
Investigation concerned ">sv» pnpili in ll classes
Drinks used included Wine. Beer and Knm in tea
mental inefficiency, bnt also because of our unreliable
judgment.
Alcohol Shortens Life. — At least nineteen of the great
American life insurance companies do not consider thai ;i
man who uses alcohol is a good risk, because be does not
live so long as the man who abstains. The statistics of
one insurance company, which cover the period 1*H4-
1909, show that during that
period 79.7 % of their risks
who were moderate drinkers
died ; while but 52.2 °f0 of
the abstainers died. In the
case of a second company,
during the period 1886-1909,
93% of the drinkers and only
70 % of the abstainers died.
168. Alcohol, a Narcotic. —
Before studying this subject
further, we must understand
the meaning" of the terms
poison, anesthetic (an-es-
thet'ik), and narcotic. A
poison is a substance which
when taken into the body
tends to cause death. Aco-
nite, opium, carbolic acid,
and mercury are all poisons, and when taken in sufficient
quantities cause death.
An anesthetic is a substance like ether or chloroform,
which when breathed into the lungs causes a temporary
loss of sensation. However, unless anesthetics are admin-
istered properly, they may cause death.
A narcotic is a substance which causes dullness or
stupor, and even a temporal}' relief from pain.
= Highest W. Fair nans Poorest
134 Abstaining Children
42% 49
y//Mw/W/Z$Z>/.. J
164 Who Drank Occasionally
34% 57' ;
■
219 Who Drank Once a Day
29'
71 Who Drank Twice a l):i\
25% 58 18',
Highest Scholarship Decreased, Peered In-
creased, as the I se of Lleohol »;is Increased
[nveatigation bj E. Bajrr, School Din
Figure 231
222
THE NERVOUS SYSTEM OF MAN
Assaults and Drink
1,115 Assaults in Heidelberg, Ger., 1900-1904
66.5'; Committed in Saloons
8.8%
7.8%
7.7%
9.2%
Committed in Street
Committed in Workshop
Committed at Home
To understand how alcohol comes to be classed as a
narcotic, it is necessary to learn about a substance called
lipoid (Greek, lipos, fat ; eikos, like).
" Within recent years a new sort of body substance has
been discovered, and has been elevated to first-rate im-
portance. This new class is termed 'lipoid.' Its impor-
tance is immense. It is quite as important in the body as the
nitrogenous or albuminous
material which is present in
every living tissue. It is
very like fat in many re-
spects, but in other respects
it is different. It contains
nitrogen, which fats do not;
it contains phosphorus,
which fats do not; again it
mixes with water, which, as
is well known, fats do not.
It has certain remarkable
properties, in that it can
make certain bodies soluble
which are otherwise not
soluble.
" The walls of practically
every living cell in the
whole body are made
chiefly of lipoid, and it is found that there are strands
of this material running through and through the sub-
stance of every cell. In fact, there is no region of any
cell in any part of the body that is without this material.
" Perhaps the largest accumulation of lipoid is that in
the nervous system. There is far more lipoid in the
brain than in any other tissue. If you examine a nerve,
or what physiologists call a nerve trunk, you will find
Place Unknown
Man; assaults committed outside
the saloon were also due to drink
The Sober Man Thinks Before He Acts
Alcohol Makes a Man Act Before He Thinks
It causes irritability ; weakens the
judgment and self-control needed
to hold irritability in check
" Our statistics (from the United States)
point to the conclusion that intemperance
is the one moxt prolific source of the
criminal co)u/itio}i.'n — Co.m.m. of Fifty.
Figure 232.
ALCOHOL, A NARCOTIC
223
that this nerve is composed of many thousands of nerve
fibers, and each nerve fiber that conveys messages into or
out of the brain is invested with an insulation jacket (sim-
ilar to the insulation covering an electric wire) of Lipoid
and thus the stimuli are prevented from scattering.
"It may be asked, 'What has all this to do with
alcohol?' The connection is an important one, for only a
few years ago two physiological investigators, — one with
the English name of Overton, and the other with the dis-
tinctly German name of Hans Meyer, — without knowledge
of each other's work, discovered the principle that any
substance that dissolved lipoid, or, what is the same thin.;,
is dissolved in lipoid, is an anesthetic. Chloroform, ether,
and all of these agents which are used in modern surgery
to produce unconsciousness are dissolvers of lipoid.
"Besides acting as anesthetics such substances act as
poisons to every living thing in the body as well. The
brain, owing to its high
tt'iciency Onter
Wora Centers
Balancing Centers
BreathingCeM.r
Hrtii Ccnler
percentage of lipoid, is
more sensitive to the
action of chloroform than
other organs of the body.
" When chemists and
physiologists found that
alcohol is soluble in
lipoid, it enabled them
to rank it as a narcotic
poison, and it is now so
classed. This statement
is altogether irrespective of the effects it will produce
on an animal." — Osborne.
The question of brain efficiency is further illustrated by
Figure 233. Long before birth the heart in the embryo
begins to beat and is under the control of the nervous
Nerve to Heart
Figure 233. — Brain Control.
224
THE NERVOUS SYSTEM OF MAN
Abstainers' Advantace
In a Championship Walking Match
MATCH HELD AT KIEL, GERMANY, 1908
59 Non-Abstainers, 24 Abstainers Entered
Contestants Entering Match
Kon- Abstainers 71% Abstainers 29%
Percentage of Prizes Won
By \nn- Abstainers 40% By Abstainers 60%
Of First 25 to Reach Coal
system. The part of the brain which superintends the
heart is located in the medulla, where a special cluster of
cells sends out nerve fibers which enter the heart nerve.
These nerve cells are called the heart center.
The next nerve center to begin work is the breathing
center, located close to the heart center, which controls the
breathing. This does not become active until after birth.
About a year after birth, several more nerve centers be-
come active in the child's brain. These are the ones which
help him to walk. The cere-
bellum contains nerve cen-
ters which play an important
part in walking and in learn-
ing to balance. The muscles
which move the arms and
legs are regulated by nerve
centers in the cerebrum.
Soon after the child learns
to walk, he begins to talk
and learn words. The sev-
eral nerve centers which now
become active are all located
in the cerebrum. These are
the nerve cells which are
necessary in speaking, hear-
ing, reading, and writing
words.
After fifteen years of age
the brain goes through important structural changes and
the young person begins to do difficult tasks well. It is
difficult to locate the exact spots in the cerebrum where the
nerve centers are that now become active, for they are
widely distributed. These nerve centers may be called
the efficiency centers and they are the last to develop. But
Failed to Reach Coal
94% were Non- Abstainers 6% were Abstainers
Abstainers won 1st, 2d, 3d, 4th, 8th Places.
Xon-Abstainers, 5th, 0th, Tth Places.
Figure 234.
STRUCTURAL CHANGES DUE TO ALCOHOL 22.")
as they become active, every one becomes skillful along
some particular line, although many years of training are
necessary before the maximum of efficiency is reached.
The efficiency centers which are the last to become ac-
tive and which require so much energy to train properly
are the first to be affected by alcohol.
169- Structural Changes Due to Alcohol. — Definite changes
are found in the protoplasm of nerve cells after the use of
alcohol. These consist in a shrinking of the nucleus, the
loss of the spindle-shaped (Nissl) bodies (Figure 224),
the swelling of the cell, and the presence of vacuoles
in the cytoplasm. It is also probable that some of the
nerve cells are actually destroyed. These physical
changes explain why the results are so great and why
complete recovery of mental efficiency in the drunkard is
so doubtful. The modern point of view and the one
which is becoming firmly established in the treatment of
drunkards by physicians is that alcoholism is a disease.
Many of the authorities on alcoholism are urging that
drunkards should be cared for just as we care for people
sick with diphtheria or tuberculosis.
Anything which can destroy all of the higher and finer
emotions, take away ambition, destroy shame, modesty,
pride in personal appearance, render one especially liable
to common diseases, or lead unerringly to insanity is
to be avoided by those who are strong enough to resist,
and should be made inaccessible to those who are weak
and ignorant. And alcohol has all these effects on man.1
1 Alcohol tills our state hospitals for the insane. Insanity is a disorder <>f
the mind due to various causes. The one cause which produces thegreatesl
number of cases is the intemperate use of narcotics, «>f which ah-,, In, I in it-
various forms is the most common. No less than twenty-sis per cenl .>!' the
inmates of our state institutions for the insane have become deranged :i- the
result of intemperance.
There can he no doubt that some persons air more Busceptible t" the in-
fluence of alcohol than others. They become easily intoxicated and readily
226 THE NERVOUS SYSTEM OF MAN
170. Tobacco. — " Training starts to-morrow, no more
smoking," is part of the athletic coach's orders at the
succumb to disease. Others appear to resist the daily use of moderate quan-
tities for a long time and, to the ordinary observer, seem to be in good health.
Slow changes, not easily detected, however, are taking place in the blood
vessels, brain, stomach, and other organs, which will in time become apparent
in serious ill health. Tbese changes are organic, that is, the structure of the
organs is changed, and even if the alcoholic drinks be then wholly aban-
doned, the organs will not return to a healthy condition — though further
damage may be averted by this course.
" Influence of Alcohol on the Development of the Brain. The brain and
spinal cord do not reach complete development until the age of twenty-four or
twenty-five yeai'S. During that time it is of particular importance that they
be well nourished, supplied with an abundance of pure oxygen by the blood,
and that all substances likely to injure their delicate structure be excluded.
One would not expect to produce a fine flower from a plant which had been
neglected or abused. It is well known to the florists who raise wonderfully
beautiful chrysanthemums that perfect blooms cannot be produced on
plants which have suffered even a slight injury from drought or other cause.
No amount of care subsequently bestowed will result in anything more than
a mediocre blossom. The human brain is in structure and function the most
wonderful product of nature. It needs even more than a plant to be protected
from harmful influences, in order that its millions of tiny cells and fibers may
be properly built up day by day as the brain and body grow. Alcohol will
produce in a mature man such a disturbance of the functions of the brain and
spinal cord that he will be for a time unable to walk steadily or to speak
distinctly. It would be idle to expect the immature nervous system of a boy
or girl to develop properly if exposed, even occasionally, to the influence of
such a powerful poison. The bad effect is twofold. Healthy growth is inter-
fered with, and the habit of craving a stimulant is more easily acquired than
in an adult. The same is true of the tobacco habit ; it is seldom contracted
except in early life. It has been found among those who became insane from
the use of alcohol, that a very large majority began its use when less than
twenty years of age.
" Persons most easily harmed by alcohol are those who are most suscepti-
ble to it. One who becomes intoxicated by a relatively small quantity of
alcohol, who when under its influence shows a change of disposition by speech
or behavior different from what is normal to him, or who after its effects have
passed away cannot remember what he did or said while under its influence,
has this susceptibility. Its continued use by such a person will inevitably
lead to the most serious results. The same is true of all women. Women
and girls are more susceptible to alcohol than the opposite sex, and show, at
an early period, that peculiar blunting of the intellectual and moral faculties
which make their appearance at a later period in men." — R. H. Hutchings,
M.D., Superintendent, St. Lawrence New York State Hospital for the Insane.
HOW THE SMOKER'S HEART IS AFFECTED 227
beginning of eacli season. lie knows that the boy who
smokes cannot reach his highest efficiency <>r be relied
upon at critical times in the contest. He would rather
have boys who do not smoke, because they an- stronger,
larger, and steadier than those who smoke. The cigarette
habit has spread until it threatens the health of thousands
of boys of America to-day. How is it known that their
health is not so good ? The charts on "smoker's heart'
prove this point.
171. How the Smoker's Heart is Affected. — The follow-
ing illustrations on the rate of the heart beat and the
strength of the pulse, by W. A. McKeever, show what
really happens when we smoke. There is much in these
illustrations to warrant the conclusion that the heart of
the habitual cigarette smoker is weak and feeble, except
for the few minutes during which he is indulging the
habit, and that the pulsations at this time are unduly
excited. Figure 235 shows three records of a young man
nineteen years old who began smoking cigarettes at the
age of fifteen and who inhaled the fumes. The three
records were taken without removing or readjusting the
instrument, as follows : No. I, immediately before smok-
ing ; No. II, during the indulgence of the habit, and No.
Ill, fifteen minutes later, after the effect of the narcotic
had become apparent. Now, by reference to Figure -3»>,
No. Ill, we may observe how this young man's heart
should record itself, for the latter is the tracing of the
heart pulsations of a normal young man of the same age
and temperament. Nos. IV to VI ( Figure -'■).'>) are repre-
sentative of another inhaler twenty years old, who began
the practice at thirteen. He now uses a strong pipe.
In Figure 236, Nos. I and II, taken respectively before
and after smoking, are tracings of a sensitive youth of eigh-
teen who has been smoking only two years. Observe the
228
THE NERVOUS SYSTEM OF MAN
Figure 235.
skip of his heart beat at x and the corresponding partial skip
under the stimulus of smoking in No. II. No. Ill (Figure
236), as mentioned above,
is a tracing of a strong
healthy heart of a young
man of somewhat excit-
able temperament. No.
IV represents the phleg-
matic temperament, that
is, a person who is cool
and calculating. No. V
is the heart tracing of a
strong and healthy
young woman.
In Figure 237, Nos. I
and II are the pulse records of a man of splendid physique,
thirty-six years old and weighing 230 pounds. No. I
was taken before and No. II after smoking a cigar. He
does not inhale. His pulse responded readily to the
stimulus, but as the first tracing indicates he does not
seem to suffer from any
heart prostrations be-
tween indulgences.
No. Ill is the record of
a person whose vitality
is temporarily low from
nervous fatigue. No.
IV is the record of a
young woman who was
on the verge of nervous
prostration. No. V is
representative of a heart
weakened by long indulgence in the smoking habit. The
young man in question began early and continued the
Figure 236.
SMOKING AND SCHOLARSHIP
•2-l\)
practice till his physician convinced him of the extreme
danger threatening his life. The pulse wave is nearly
normal in length, but is entirely too weak. Under such
conditions of heart a man is capable of Little courage or
aggressiveness.
Figure 237.
"From the foregoing evidence we are led to the con-
clusion that in the case of boys and youths cigarette
smoking is very dele-
terious to the physical
and mental well-being.
Moreover my investiga-
tions indicate that it
makes very little dif-
ference in the effects
whether the victim uses
pipe or cigarettes, pro-
vided he inhales the
fumes ; and with few
exceptions the young
smokers are inhalers. The ordinary case exhibits about
the following type of conduct : (1) While the craving is
at its height the victim manifests much uneasiness and
often much excitation. (2) During the indulgence the
cheek is alternately flushed and blanched, the respiration
considerably increased and the hands tremble. (3) About
twenty minutes after smoking the muscles become relaxed.
the respiration slow and shallow, the skin on the face dry
and sallow and there is an apparent feeling of unconcern
about everything." — W. A. McKeeveb.
172. Smoking and Scholarship. — Several thousand boys
have been studied and classified according to acre and
whether they were smokers or non-smokers. In all cases
the non-smokers had a higher average grade of scholar-
ship. The experience of city superintendents and prin-
230 THE NERVOUS SYSTEM OF MAN
cipals is that they can usually tell a cigarette boy by his
general attitude, poor scholarship, and disregard of per-
sonal appearance.
When cigarettes are burned, three distinct poisons are
produced, which cause serious effects on the boys who use
tobacco in this form. These poisons are absorbed in small
quantities by the mucous membrane which lines the nasal
passages and in larger quantities when the smoke is in-
haled in the lungs.
A simple way to prove that cigarette smoke contains a
poison is by blowing the smoke through a glass tube into
an aquarium containing goldfish. Only a small amount
of smoke wrill kill the fish.
While we can all gradually adapt ourselves to small
amounts of poison, poisons are never beneficial unless pre-
scribed by a physician to try to remedy some bodily defect.
The poisons which arise from the burning of a cigarette
are never prescribed even as medicines, and have never
been found in any way beneficial to the human body.
SUMMARY
The nervous system of all vertebrates consists of a brain
and spinal cord with nerves passing to all organs of the
body. The brain of man is the most highly developed.
All our movements are controlled by means of the nerv-
ous system. Through our sense organs we gain our
information of the world.
The nervous system is made up of cells which are
highly specialized. Their main work is to transmit and
interpret stimuli. The nerves of man are so highly spe-
cialized that all stimuli which affect the eye are thought
1 > v us to be light stimuli ; or all stimuli which enter in
the ear, seem to be sounds. The information which passes
over any of our special sense organs travels over several
QUESTIONS 231
different nerve cells before it reaches the place in the
brain where it is interpreted. The highly specialized
nervous system and sense organs grow and arc fed just
as muscles or skin grow and are fed. There is n<> Bpecial
food which we can eat that is used exclusively by the
nervous system.
QUESTIONS
What is the nervous system? Of what parts is it composed?
What animals have you studied that have a nervous system ? Which
ones lacked a special nervous system? How docs the nervous system
grow? Describe the nerve cell. How docs it differ from other cells
in man? What are special senses ? What kind of information do you
receive through your eyes? What kind through your tars ? Which d<>
you remember? (The well-trained mind remembers equally well the
information that comes in through each of his sense organs. )
To most of us it is given to play an unimportant n">l<'
in the period in which we live. Inheriting from our
parents healthy, normal bodies we can at least pass on
this priceless heritage to our children. It will be their
chief pride, as it is ours. Life is not easy, and we need
the best bodies, the best nervous systems, ami tin* besl
trained minds that it is possible for us to have in order
to make our lives count for the most. This means that
it is the duty of every boy and girl to know about sani-
tation, public and private hygiene, and disease.
REFERENCES
Cutten, The Psychology of Alcoholism.
Davenport, Heredity in Relation to Eugenics.
Guyer, Being Well-born.
Horsley and Sturge, Alcoholism and the Human Body
CHAPTER XIX
*
THE BIOLOGY OP DISEASE1
STUDENT KEPORT
How many in the class have been sick during the past year ? Of how
many different diseases ? What was done to aid each one in getting
well ? What was done to prevent others from taking the same diseases ?
What was done by your Board of Health officer ? (Consult the reports
of the State Board of Health and of the local health official.)
173. Disease. — Usually people go through their daily
occupations without feeling pain or bodily discomfort.
Such a condition is known as health. Sometimes, how-
ever, they go about their usual duties when they do not
feel well and the indisposition gradually passes away.
But in other cases the ill feeling becomes severe, the usual
activities are given up, and we say that they are sick.
Sickness may last for only a short time or for many years.
The usual conditions of the body are changed, and we say
that the body is diseased. The apple, the tree, the dog,
the horse, each has its own diseases.
174. Cause of Disease. — While there are many causes of
disease, all of them may be grouped under four headings:
(1) Inherited diseases, i.e. those transmitted from parent
to child, as certain forms of insanity and imbecility where
the exact cause is not known. (2) Diseases caused
by such poisons as lead, arsenic, mercury, phosphorus,
opium, cocaine, alcohol, and the like. The disturbances
which these chemical agents set up in animal tissues are
1 Chapter XXII, Bacteria, may be read in connection with this chapter.
232
COMMUNICABLE DISEASES 233
easily recognized by a good physician. (3 ) I diseases which
cause certain tissues to take on an abnormal growth, as in
tumors and cancers. (4) Diseases caused directly or
indirectly by some definite living plant or animal. Such
diseases are called " biological diseases," because the source
or cause is in all instances some definite living plant or
animal. In our ordinary daily speech we often speak of
such ills as " germ " diseases.
175. Biological Diseases. — The rattlesnake secretes a
poison which is forced through fangs or hollow teeth into
the blood of its prey. This poison affects the heart and
may result in death. One of the common and beautiful
mushrooms produces a similar poison which is nut de-
stroyed by cooking. If this particular mushroom is eaten,
death is almost certain to follow in from twenty-four to
forty-eight hours. In both of these cases the animal or
plant is large enough to be seen and easily recognized.
But there are a considerable number of microscopic
plants and a few microscopic animals that have formed the
habit of living for at least a part of their life in other
plants and animals. During this time, as we have seen in
the study of animal parasites, they usually secure all, or the
greater part, of their food from the plant or animal in
which they are living. Two general causes of disease re-
sult from this parasitic habit. The parasite may destroy
certain cells of the body, or the material thrown off from
the body of the parasite may act as a specific poison.
176. Communicable Diseases. — The term communicable
disease 1 is used in this book to mean the diseases caused by
1 New York State designates t be following as communicable diseases:
anthrax; chickenpox; cholera, Asiatic: diphtheria (membranous croup);
dysentery, amoebic and bacillary ; epidemic cerebrospinal meningitis; epidemic
or streptococcus (septic) sore throat: German measles: glanders; measles;
mumps; ophthalmia neonatorum; para-typhoid lever: plague; poliomyelitis,
234 THE BIOLOGY OF DISEASE
a plant or animal living as a parasite in plants, animals, or
man. These diseases are communicated in various ways
from one individual to another, from one animal to an-
other, or from one plant to another.
The following are among the most common communi-
cable diseases. Diseases caused by bacteria (minute plants)
are tuberculosis, pneumonia, diphtheria, typhoid fever,
bubonic plague, and whooping cough. Measles and scarlet
fever are so similar to
I these in many ways
that it is believed that
they are caused by
^_ ^^ bacteria, although the
^_ ^^ definite bacteria which
cause them have not
been discovered. Dis-
eases caused b}^ proto-
■ ? rp -a o wi zoa (minute animals)
Diphtheria Measles Tvphoid Scarlet Whooping ^ '
fever cough are malaria, yellow
Figure 238. — Deaths from Communicable fever sleeoina" sick-
Diseases. ' ,* °
, , ness, possibly small-
This is for the year 1913 in New York r J
State. pox, and others less
well known.
The biological diseases are all preventable, especially
the communicable diseases which result from the parasitic
habit of some plant or animal. In order to prevent these
diseases, it is necessary to know how the different plants
and animals gain access to the human body and proceed
to live there. This can be illustrated by describing pul-
monary tuberculosis, a plant or bacterial disease ; and
malaria, an animal or protozoan disease.
acute anterior (infantile paralysis); puerperal septicaemia; rabies; scarlet
fever ; smallpox ; trachoma ; tuberculosis ; typhoid fever ; typhus fever ;
whooping cough.
Robert Koch (1843-1910) was a celebrated German physician,
noted as the discoverer of the bacilli of tuberculosis and of cholera.
In 1882 he announced in Berlin the discovery of the tubercle
bacillus, and the same year he published a method of preventive
inoculation against anthrax. Later he discovered tuberculin, a
substance intended to check the growth of the tubercle bacillus.
In 1883, Koch led the German expedition to India to investi-
gate cholera, and discovered the cholera germ. In 1885 he be-
came Professor of Medicine at Berlin and in 1891 Director of the
new Institute for Infectious Diseases.
PULMONARY TUBERCULOSIS 235
177. Pulmonary Tuberculosis. — Pulmonary tuberculosis
is a disease located in the lungs. The cause is ;i definite
plant with parts and habits which are easily recognized by
bacteriologists (students of bacteria). This plant is called
Bacillus tuberculosis, and was proved to be the cause of
consumption, or tuberculosis, by Robert Kocli, a German
scientist, in 1882. These tuberculosis bacteria, or germs,
in countless numbers are found leading a parasitic life in
the lungs of a tubercular patient. The bacteria are ex-
tremely minute, and can be seen only by the use of a
microscope of high power.
The large number of germs in the lungs grow rapidly
and they are set free in the air by coughing. One tuber-
culosis patient may give off millions of these germs in a
day. For this reason great care should be taken in destroy-
ing the sputum of patients, for if the germs become dry.
they are carried about as dust particles.
Tuberculosis and other disease germs are so numerous
that it is impossible to escape taking some of them into our
bodies, but they usually do us no harm unless we are in a
weakened condition.
Modern methods of cleaning the streets by flushing witli
water, keeping garbage covered, and wiping up tin- dust
in our homes instead of using the old-fashioned feather
duster are doing much to keep down the number of germs
in the air which we breathe.
The bacteria that are breathed in from the air may find
some weak place in the lungs in which to take up their
parasitic lives. Those which enter on the food pass from
the digestive tract into the blood and are eventually carried
to the lungs. The introduction of tuberculosis germs in
this way is especially frequent in children. In many
cases milk from tuberculous cows is the source of the
disease germs. See § 248, page 34(.*.
236
THE BIOLOGY OF DISEASE
The cause of pulmonary tuberculosis is, then, the tuber-
cle bacillus, which is taken into the lungs in the air we
breathe, or through the food eaten, or by personal contact
with a consumptive patient. These germs cause certain
parts of the lungs to become diseased.
178. Getting Well. — Consumption is not necessarily
fatal, especially if treated in its earliest stages. But many
Figure 239. —Tuberculosis Cure, Summer.
people who have the disease do not consult a regular
physician until it has made considerable progress, and
then it is too late to bring about a cure.
Figures 239 and 240 show the present method used in
treating tuberculosis. The patients are given tissue-build-
ing food (protein) and are required to sit and sleep out-
of-doors as much as possible. Rest, good food, and fresh
air work wonders in arresting the progress of this disease.
When the body gains the requisite amount of strength
MALARIA. A PROTOZOA X DISEASE
'IM
the disease and its germs are usually thrown off. Patent
medicines and alcohol should be avoided, as they reduce
the power of the body to resist disease and give no aid
in building up the diseased tissues. In addition, alcohol
causes serious disturbances in the general circulation.
Figure 240. — Tuberculosis Cure, Winter.
In addition to pulmonary tuberculosis physicians recog-
nize tuberculosis of the throat, intestines, kidneys, brain,
and joints.
179. Malaria. A Protozoan Disease. — Malaria is a disease
caused by a protozoan or minute animal which is dis-
tributed over the greater part of the world. The malaria
protozoan is a minute simple cell of living matter. It
resembles the amreba in its form and ability to chancre.
This parasite penetrates into the red blood corpuscles and
remains in them for twenty-four or forty-eight hours, or
until the substance of the corpuscle is nearly used up.
238
THE BIOLOGY OF DISEASE
Then the parasite escapes into the plasma of the blood and
later enters a fresh corpuscle.
180. Source of the Malarial Parasite. — The word malaria
means bad air, for it was formerly believed that foul air
caused the disease. When it was learned that a definite
animal was the cause both in man and in other animals,
the problem was to find how the parasite entered the bod}^
Figure 241. — Malarial Swamp.
An ideal place for mosquitoes to breed. ]
It has been proved to the satisfaction of scientists that the
malarial protozoan is injected into the blood by a particular
kind of mosquito (Anopheles) which carries malaria germs
in its body.
The mosquito sucks the blood from a man or an animal
suffering from malaria. This blood contains some of the
malarial parasites, which pass into the stomach of the mos-
quito. They then migrate into the salivary glands of the
mosquito, so that as soon as the mosquito bites another
man or animal, it pours out some saliva which intro-
duces the parasites into the victim's blood. While in the
PREVENTION OF COMMUNICABLE DISEASES 239
body of the mosquito, these parasites pass through definite
stages in their life history; and when they reach tin-
blood of man, the remaining stages are completed. Thus
a man, or an animal, and a particular mosquito are neces-
sary for the complete life history of the malarial parasite.
This means in addition that for the prevention of
malaria all that is necessary is to destroy the Anopheles
mosquito, or in case this cannot be done, to screen ade-
quately the houses, tents, and bedrooms in the regions
where the mosquitoes live. It is interesting to note that
this discovery of the cause of malaria and the methods for
its prevention was more than anything else responsible for
the successful completion of the Panama Canal. The con-
struction of this important work was more a health than
an engineering problem.
181. Other Protozoan Diseases. — Other protozoan dis-
eases are produced in the same manner as malaria. The
carrier may be different, but the principle of spreading
the diseases is the same. Yellow fever, for instance, is
spread by another kind of mosquito, and sleeping sickness
by the tsetse fly.
182. Hookworm Disease. — This disease is caused by a
parasite which is classified as one of the worms. Hook-
worm disease belts the earth in a zone which extends thirty -
three degrees each side of the equator. Great progress
is being made in the United States in curing those su lin-
ing from this disease. The wearing of shoes and the use
of a sanitary closet are usually sufficient preventives bo
protect the people who live in a hookworm district.
183. Prevention of Communicable Diseases. — The pre-
vention of these diseases depends upon an understanding
of the causes which produce them, close adherence to the
laws of hygiene, and especially the exercising of proper
care in the production and cooking of our food. Germ
240 THE BIOLOGY OF DISEASE
diseases are unnecessary, and it should be considered a
disgrace to a community if some of them appear. Proper
hygienic measures will do much towards eliminating
most of the communicable diseases, but until the intelli-
gence of communities can be aroused enough so that such
measures shall be insisted upon, we must depend upon
proper food, rest, fresh air, and exercise to keep ourselves
fit, and thus avoid the conditions which help disease to
■ TLa ■ .hu'.ihlT^*j<
_^0
* - ___ —
■ ■ . ■
K ^H
'■ 1
Figure 242. — A Model Reservoir.
gain a foothold. Tuberculosis, for example, is more likely
to occur in persons who are underfed and overworked,
and a cold often follows an attack of indigestion.
Care of Food. — The care of food is extremely neces-
sary in preserving our bodily well-being, for the same
germs live and grow in food which cause disease when
taken into our bodies. One method of keeping the bac-
teria on food from growing is by proper refrigeration.
The temperature of a well-cooled refrigerator does not
destroy the germs, but makes them incapable of growth
until heat is supplied them. So if food is taken from the
refrigerator and allowed to stand for a time, the bacteria
will at once begin to grow and cause the food to spoil.
PREVENTION OF COMMUNICABLE DISEASES 241
If such food is eaten, an intestinal disturbance usually
results.
In the attempts to prevent disease, more study has been
given to milk and water than to other foods. For discus-
sion of milk, see pages 347-350.
While milk is used as a food by all mankind, water is
even more important, for it is absolutely necessary if we
Figure 243. — A Poor Reservoir.
Note the open stream that empties into the main body of water.
The impure water of the Erie Canal drains into this open stream.
are to continue to live. In this respect man is like all
plants and all other animals, water being necessary for
the preservation of all life.
Two conditions must be met before a water supply can be
deemed satisfactory. There must be an abundant supply;
but more important still, the water must be pure, that is,
free from disease-producing germs. Farmers and residents
of small towns ma}r without great trouble secure sufficient
pure water, but the large cities have to spend millions of
dollars in providing an adequate water supply.
242
THE BIOLOGY OF DISEASE
Sanitary measures are adopted to keep the sources of
the water from becoming impure, as well as to keep clean
the reservoir where it is stored. Certain harmless plants
and animals living in reservoirs may give an unpleasant
taste or odor to the water. Harmful disease germs live
in water for months. Such germs may be frozen in ice,
stored in ice houses, and when later put with the ice into
drinking water, may cause typhoid fever. It is, therefore,
important that we have
plenty of pure water, and
we should do all we can
to help in giving the
town or city in which we
live a pure water supply.
Introduction of
Antitoxin Treatment
STUDENT REPORT
Prepare a report on the water
supply in your locality and find
where it comes from. What
measures are taken to keep the
sources and reservoir clean ?
184. Keeping Well. —
Our best doctors are
spending much effort in
showing how to avoid
disease, for no one is
benefited by illness. The
old notion that children should be exposed to measles,
scarlet fever, and whooping cough is wrong, for none of
these childhood diseases is necessary. The time will come
when our homes and surroundings will be so sanitary
that the common diseases caused by germs will be elimi-
nated, or at least decreased in number.
Government inspection of meats is lessening the amount
1881 87 89 91 93 '95 '97 1900 02 04 06 08 10 12 14
Figure 244. — Diagram.
Thirty years of diphtheria in New
York State.
KEEPING WELL 243
of disease contracted from eating diseased pork, incut, and
fish. The United States Department of Agriculture is
making every effort to inspect such products, and tin-
department is fairly successful in inspecting the larger
establishments. However, many cattle and hogs are killed
and sold locally and they escape inspection, so that buyers
IF
THESE CASES THESE CASES
HAD BEEN REPORTED WOULD r^VER MAVE OCCURRED
JO
25
3l5
S
Ct
|:0
*■
On Fabm On Faom
J I 1J
M 17 21 30 I 2 4 6 6 10 12 14 16 « 20
Mm S 7 9 II 13 15 17 19
June
21 . , 27 9 II M 17 21 30 I 2 4 6 6 10 12 14 16 « 20 23 JO
Afri Mm 5 7 9 ll 13 15 17 19 T
The Story of the Epidemic op Septic Soke Throat at Rockvoxe Centre. L. I.
Figure 245.
of this meat have no protection against a general condition
of disease.
Another danger to health is from the people known as
"carriers" of disease, as such people give no evidences of
illness. Typhoid and diphtheria are the two diseases
most likely to be carried in this way. Many of these
carriers serve as cooks, and as they give no evidence of
being in other than perfect health, they often spread the
germs through the food they prepare. If habits of abso-
lute cleanliness are insisted upon, much of the danger of
the dissemination of srerms in this way will be removed.
244 THE BIOLOGY OF DISEASE
Many hotels, public institutions, and well-run house-
holds insist that a prospective servant shall be examined
by a competent physician before being engaged for work.
In this way carriers may be detected, and persons with
germ diseases, like tuberculosis, for instance, are pre-
vented from spreading disease either in the food or in
the air.
( hildren in the schools frequently have diphtheria germs
living in their nasal passages or throats, but are not ill.
After a time a number of children come down with the dis-
ease. A doctor then takes a sample of the contents of the
throat and nose of each child. The bacteria in the mucus
from the nasal passages is allowed to grow for twenty-four
hours in a special preparation called a culture (page 346).
At the end of that period the cultures are stained and ex-
amined with a high power of the microscope, and if diph-
theria germs are present, they are easily seen. If one of
the well children has these germs, he is treated until they
disappear.
185. Quacks and Patent Medicines. — The term quack is
applied to a person who advertises that he can cure vari-
ous diseases by some new invention or newly discovered
remedy. A patent medicine is one which has been regis-
tered at the patent office, and this registration gives the
patentee exclusive right to the use and name of the so-
called remedy. Many millions of dollars are spent an-
nually in advertising special " cures " and new mechanical
contrivances guaranteed to cure diseases for which they
can do nothing, or even to cure such diseases as cancer,
for which there is no known remedy.
Many people who do not understand the causes of dis-
ease are reluctant to consult a well-trained physician, but
read and believe the carefully worded advertisement of
some quack doctor or of some patent medicine. The
ALCOHOL AND DISEASE 245
untrained sufferer cannot interpret the meaning of his
distress and is incompetent to select the proper medicine.
As real medicine is given for specific symptom- associated
with a specific disease, it is apparent that ;i patent medi-
cine advertised to cure from six to forty diseases is worth-
less. Furthermore, real medicine is given to relieve a
certain set of symptoms at a given stage of the disea
and is frequently changed. This is, of course, impossible
when using a patent medicine. If every one would eon-
suit regular physicians, and cease patronizing the quacks
and patent medicines, one of the sources of much sickness
and suffering would be destroyed.
186. Alcohol and Patent Medicine. — Repeated chemical
analysis of many of the patent medicines shows that they
contain a considerable amount of alcohol. There are over
120 patent medicines which the United States Government
will not permit to be sold except by the possessor of a
liquor license. This fact alone shows the harmful nature
of patent medicine.
187. Alcohol and Disease. — It is unnecessary to make an
elaborate series of quotations from eminent men to prove
that alcohol is not useful and necessary as a medicine in
the cure of disease. One of the chief reasons has already
been given in connection with the discussion of tubercu-
losis. There is no evidence that alcohol has any effect "ii
the destructive course of a disease, or any beneficial
effect upon the person suffering from disease. This last
phase of the problem has been under critical study Long
enough to show that the earlier claims of the helpful-
ness of alcohol in disease are not supported by the facts.
The reverse is true. Alcohol is known t«> decrease the
power of the body to withstand disease and dm>s not
assist in destroying the poisons which arise in the
case of bacterial diseases. At present there is no
246 THE BIOLOGY OF DISEASE
scientific evidence which justifies the use of patent
medicines, or of alcohol unless definitely prescribed by a
physician.
188. Headache and Anti-pain Patent Medicines. — Many
preparations advertised under these general names are
taken by persons ignorant of the fact that these medicines
generally contain harmful drugs. It should be sufficient
to know that no reputable doctor will ever give any of
these preparations except in a mild form, and in case of
extreme pain. No person except a trained physician has
a right to prescribe drugs ; and he only after a knowledge
of the patient's symptoms. Many of these preparations
affect the heart and blood, and none of them has any
beneficial effect on the real cause of the pain.
189. Boards of Health. — Communities and physicians
have endeavored to prevent the spread of communicable
diseases by the formation of boards of health, by quaran-
tine, vaccination against smallpox, immunization against
typhoid fever, the use of antitoxin in diphtheria, disin-
fectants and fumigants.
The term Board of Health is applied to a number of
individuals, appointed or elected by a nation, b}^ a state, or
by a community, to enforce the national, state, city, or town
health laws and regulations. The local officer of this board
is a physician, and in some states, New York for example,
is appointed according to the regulations governing the
city or town in which he is to serve. The New York state
law defines his work as follows :
" Every such local officer should guard against the intro-
duction of such communicable diseases as are designated
by the State Department of Health by the exercise of
proper and vigilant medical inspection and control of all
persons and things infected with or exposed to such
diseases, and provide suitable places for the treatment and
QUARANTINE
247
care of sick persons who cannot otherwise be provided
for."1.
Violation of quarantine and of the various health regu-
lations, such as the pollution of water and improper care
of refuse and sewage, should be reported to the local health
officer. In case no satisfactory results are obtained from
the local health officer, the question may be referred to the
Figure 246. — Model Dairy Cow.
State Board of Health, which gives prompt and efficient
attention to all questions concerning the health of the
people of the state.
190. Quarantine. — When a person or a group of persons
is suffering from a communicable disease, or when anyone
has been exposed to the germs of the infection of any
such disease, the Board of Health may place him under
quarantine. The nature of the quarantine depends OD the
JThe Sanitary Code of the Public Health Council of the State of NYw
York defines the health officer's duties in detail and may be had by
writing to the State Department of Health at Albauy. Selections from
the Sanitary Code will be found in Appendix B.
248
THE BIOLOGY OF DISEASE
specific disease and the laws of the town or state in which
the persons reside.
The New York law on this subject is typical of the best
state laws on quarantine. It says :
"The Board of Health shall prohibit and prevent all
intercourse and communication with or use of infected
premises, places, and things ; and require and if necessary
Figure 247. — Model Dairy Stable.
provide the means for the thorough purification and chang-
ing of the same before general intercourse with the same
or use thereof shall be allowed." See Appendix B.
This means if an individual is suffering from scarlet
fever or diphtheria, or some other communicable disease,
he shall not associate with the general public until he has
ceased to be a source of infection. His liberty is tempo-
rarily restricted by quarantine because he may be the
cause of sickness and even death to others by spreading
the germs of communicable disease.
It is interesting to know that the more highly civilized
QUARANTINE
249
00
D
O
a;
SZ
JZ
o
n-
4)
<u
jz
o
c
o
sz
JZ
tn
c
4>
To
,c
o
a nation, state, or city becomes, the more specific and
exacting are the quarantine regulations. There is every
reason to believe that in the near future the present laws
250
THE BIOLOGY OF DISEASE
of quarantine will be extended. In addition to individuals
being quarantined in a dwelling, all the inhabitants of a
city or state may be quarantined in case of severe epi-
demics ; or the transportation of stock from one state to
another may be prohibited in the case of a serious com-
municable disease existing in cattle or sheep. The quar-
antine laws, for example, order from time to time that all
dogs in the town or
county shall be muzzled
as a protective measure
against rabies.
Immigrants suffering
from certain diseases are
prohibited from landing
in the United States.
This means that there
are national as well as
state and city quaran-
tine laws. The present quarantine laws are the most
effective protective measures against the spread of disease
known to man and are the product of a high degree of
civilization.
191. Vaccination. — The success which has attended the
efforts of man to overcome disease is well illustrated hy
smallpox. For centuries this disease was responsible for
many deaths throughout the world. It is said to have
existed in China centuries before Christ. Later it swept
over Europe again and again. King Frederick William
III of Prussia stated, in 1803, that 40,000 people suc-
cumbed annually in his kingdom. A famous French
physician wrote in 1754 that every tenth death was due
to smallpox, and that one fourth of mankind was either
killed by it or disfigured for life. Smallpox was brought
into the Western Hemisphere soon after the discovery
Figure 249. — Agar Plates.
Where a house fly was allowed to walk
White patches are bacterial growths.
VACCINATION
2.->l
of America and killed thousands of the Indians. It also
visited the colonies. In 1721, Boston was ravaged foi
the sixth time by this disease. Out of the 10,567 Inhabit-
ants, 5989 had the disease and 894 died.
In 179G, Jenner, an Englishman, demonstrated the fact
that by inoculation of a person with cowpox, a disease
peculiar to cows and in some way allied to smallpox, the
patient would become immune to the dreaded disease.
This was one of the greatest and
most beneficial discoveries of medi-
cine which has ever been made.
By the result of vaccination small-
pox has become a rare disease in the
civilized nations of the world, and is
least prevalent where the vaccination
laws are the most stringent.
Vaccination for smallpox consists
in the inoculation of the human
patient with vaccine, a substance
secured from a cow sufferings from
O
cowpox. This usually causes a
slight illness, but during the illness the patient acquires
a power which enables him to resist the germs of small-
pox. This acquired power of resistance is called im-
munity.
Many people do not understand the theory of vaccina-
tion and its advantages, and have opposed its use through
fear of acquiring lockjaw from the vaccine. It has been
established that proper vaccine matter never contains
the germs of lockjaw, and if this disease occurs, ii is
due to failure in keeping the arm clean during the period
when the vaccination scar is forming.
Immunity to disease is now being produced through
inoculation. The patient is inoculated, that is, there is
Figure 250. — Bacteria
and Mold.
One tenth of the num-
ber carried by one house
fly.
252
THE BIOLOGY OF DISEASE
introduced into his circulatory system a virus, or serum.
Each disease has its own virus, as the vaccine in small-
pox, and this virus produces a mild form of the disease.
This causes the cells to become resistant to the germs or
microbes of the specific disease. Inoculation is being
widely used for the prevention of typhoid fever. All
soldiers are required to take this treatment. It would
be desirable for all people to become immunized against
this disease, but those
who travel extensively
and thus have to drink
all kinds of water and
milk should certainly
undergo this treatment.
Vaccination and im-
munization reduce the
liability of death in case
the disease is acquired,
but they do not ab-
solutely prevent the disease. If a vaccinated or immu-
nized person gets an overwhelming number of germs, he
may have an infection of a slight kind. But the liability
of contagion is reduced to a minimum.
192. Antitoxin. — We cannot say definitely why vaccina-
tion and immunization act as they do. It is known that
if a poison (toxin) produced during a case of diphtheria
is gradually introduced into the blood of a horse, a sub-
stance is produced which destroys the injurious effects of
the diphtheria poison. The serum from the blood of the
horse is called antitoxin, and may be preserved for use at
any time to destroy the influence of the diphtheria poi-
son. A given amount of this antitoxin is introduced into
the blood of the patient suffering from diphtheria, and
this usually counteracts the disease. This treatment has
Figure 251. — Milk Diluted to j-^-
Left-hand culture from clean milk ;
right-hand culture from dirty milk.
DISINFECTION AND DISINFECTANTS 253
saved countless lives. It is estimated that in the ten
years after the discovery of the diphtheria antitoxin the
lives of a million children were saved in Franc- alone.
State boards of health usually furnish antitoxin for diph-
theria and lockjaw.
LABORATORY STUDY
It takes five pounds of sulphur to disinfect a room which contains
1000 cubic feet of air. Three ounces of forty per cent formalin, u> which
is added two and one tenth ounces of potassium permanganate will also
disinfect the same sized room. Compare the cost and ease with which
each is used.
193. Disinfection and Disinfectants. — The time when dis-
infectants shall be used and the manner of disinfection
have been considered important factors in preventing the
spread of communicable diseases. The purpose of <1 ^in-
fection is to. destroy the germs lodging on clothes, floors,
carpets, and curtains. People who care for the sick
should know where the germs are likely to be and how
to disinfect places where they have found lodgment.
The term disinfectants is sometimes incorrectly applied
to deodorizers, substances which are used to destroy
odors, but the word should be applied only to substances
which destroy germs or bacteria.
Disinfectants are not expensive, and few of the patented
preparations are as satisfactory as the common ones used
by boards of health. Weak solutions of carbolic acid and
bichloride of mercury are chiefly used for killing the
germs on the hands and clothing, or f»»r cleaning tin-
woodwork in the sick room. Chloride of lime is used to
kill the germs in the discharges of the body, and Bulphur
dioxide and formaldehyde gas for the final killing of the
germs in the room or the whole hoitse before it is occupied
again.
254
THE BIOLOGY OF DISEASE
Never use any methods of disinfection unless they have
been personally recommended to you by a physician or an
expert in the details of room disinfection. Do not rely
upon patented solutions and methods. The latter are ex-
pensive and often practically worthless.1
194. Results of Disease. — In New York State for the year
1909 there were reported to the State Board of Health
138,315 cases of communicable diseases. There were
many. cases that were not reported, so that this is not to
be taken as the highest estimate of the number of people
who were sick with preventable diseases. During the
years 1913, 1914, 1915 in the same state the following
number of people died from these communicable diseases.
NUMBER OF DEATHS
1913-1915
1913
1914
1915
Diphtheria
1853
2015
1754
Scarlet Fever
837
687
409
Whooping Cough
818
730
749
Measles
1071
839
834
Typhoid Fever
1018
878
750
It is difficult properly to measure the value of health to
the community. When the wage earner is sick and is
placed in quarantine, the loss of money is the amount he
might have earned. In the case of a typhoid fever epi-
demic the total loss is many thousands of dollars. Further,
there is no adequate measure of the sufferings of those
who die, and the heartaches of those who survive. But
both the suffering and the financial loss can be greatly
lessened by improving our sanitary laws and aiming at a
better state of health for all the people. An increase in
1 When practicable, it is well to have the local health officer discuss
such subjects as disinfection and quarantine.
IMMUNITY 2f)5
taxes to provide cleaner streets, public playgrounds, proper
sewage disposal, and adequate inspection of milk, meat,
and water, is really an economy. For although such
improvements cost money, they are not so expensive as
epidemics of disease and the maintenance of hospitals and
of orphan asylums.
195- Heredity of Disease. — The term heredity of disease
is one which has been misunderstood by many people.
By the term heredity we mean that which is handed on
from parents to their offspring. In the case of biological
diseases which are caused by some definite' plant or animal,
it is evident that they cannot be inherited. But when t la-
parents are afflicted with a biological disease, their bodii is
become weakened and their offspring may have a poor
constitution so that they are more easily affected by disease.
196. Immunity. — Immunity is a technical term which
means that the body resists or is not susceptible to the
germs of biological diseases. Many people do not become
sick when there is an epidemic of typhoid fever, measles,
malaria, or the like. Such people are said to possess a
high degree of natural immunity to disease germs. People
usually well frequently take germ diseases when the body
happens to be exhausted by care or work. In such cases
the immunity of the body has been weakened. Many of
the germ diseases confer immunity against a second attack
of the same disease, but tins does not hold true for all
persons or for all germ diseases. Vaccination a gain si
smallpox, in the case of most persons, confers immunity
for about seven years. Inoculation with the typhoid
serum confers immunity for from two to three years. Im-
munity, then, is a relative term, and depends in a large
measure on the state of health of the individual and on
his power of resisting the poisonous effects of disease
germs.
256
THE BIOLOGY OF DISEASE
Student Report
Due to Some Plant
or Animal
Treatment by
Prevented
BY
4J
a>
s
In the watei
o
C3
3
o
s
5
u
to
CD
3
"3
<33
C
O
^—
eS
O
■ji
<o
P*
a)
5*
bo
"c
pq
_o
C5
— *
5
to
CO
o
SB
B
5
Cold ....
X
X
X
X
X
Measles . . .
Whooping cough
*
•
Typhoid fever .
X
X
X
X
X
X
X
X
X
X
Tuberculosis . .
Add others . .
197. What are you going to do and how are you going to
do it ? — We have now learned some of the facts about
how to keep well and how to do our life work effectively
and efficiently. We all begin life as children with an un-
known work to do. How well are we going to do it ?
Judge Lindsay says, " Children are the life blood of the
states. They are better producers of energy than steam
or electricity." Davenport in a new study emphasizes
this point in the following words: "The human babies
born each year constitute the world's most valuable crop.
Taking the population of the globe to be one and one- half
billion, probably about fifty million children are born each
year. In the continental United States with over ninety
million souls probably two and one-half million children
are annually born. When we think of the influence of a
Harriman, of an Edison, of a William James, the potential-
ity is far from being realized. Nearly half a million of
these infants die before they attain the age of one year,
and half of all are dead before they reach their 23d year
WHAT ARE YOU GOING TO DO 257
— before they have had much chance to affect the world
one way or another. However, were only one and a
quarter million of the children born each year in the
United States destined to play an important part for the
nation and humanity we could look with equanimity on
the result. But alas! only a small part of this army will
be fully effective in rendering productive our three million
square miles of territory, in otherwise utilizing the un-
paralleled natural resources of the country, and in foi ming
a united, altruistic, God-fearing, law-abiding, effective and
productive nation. On the contrary, of the 1,200,000 who
reach full maturity each year, forty thousand will be
ineffectual through temporary sickness, four to live thou-
sand will be segregated (placed apart) in the care of
institutions, unknown thousands will be kept in poverty
through mental inefficiency, other thousands will be the
cause of social disorder, and still other thousands will be
required to attend and control the weak and unruly. We
may estimate at not far from 100,000, or eight per cent,
the number of the non-productive or only slightly pro-
ductive, and probably this proportion would hold for the
600,000 males considered by themselves. The great mass
of the yearly increase, say 550,000 males, constitute a
body of solid, intelligent workers of one class and another.
engaged in occupations that require, in the different cast s,
various degrees of intelligence but are none the less valu-
able to the progress of humanity. Of course, in these
gainful occupations the men are assisted by a Large num-
ber of their sisters, but four-fifths of the women are still
engaged in the no less useful work of home-making.
"It is a reproach to our intelligence that we as a people,
proud in other respects of our control of nature, should
have to support about half a million insane, feeble-minded,
epileptic, blind, and deaf, 80,000 prisoners, and 100,000
258 THE BIOLOGY OF DISEASE
paupers at a cost of over one hundred million dollars per
year." — Davenport.
SUMMARY
Disease prevents us from working as we do when we
are well. Most diseases are unnecessary and preventable,
especially all which are caused by some plant or animal liv-
ing as a parasite in our bodies. In most of the biological
diseases some definite poison produced by the parasite is
taken into the body, and this is the chief cause of the disease.
As a physician knows the nature of a disease and its effect
upon the body, he can aid materially in overcoming the
illness. Each biological disease is distinct and must
have special treatment. Many of these diseases are taken
from some one who has the disease. Vaccination, quaran-
tine, and disinfection are measures which help to prevent
the spread of germ diseases. It is our duty to keep well,
and we can do much toward this by understanding how
to avoid the biological diseases.
QUESTIONS
What are the biological diseases ? How many biological diseases do
you know ? Name them. Describe a germ disease. Describe malaria.
What is vaccination ? What is quarantine ? For what diseases are
people quarantined ? What is the work of the Board of Health ? What
is the purpose of disinfection ? What are the chief disinfectants ?
REFERENCES
Celli-Eyre, Malaria.
Chalmers, The Beloved Physician Edward L. Trudeau.
Chapin, Sources and Modes of Infection.
Conn, Bacteria in Milk.
Cornell, Health and Medical Inspection of School Children.
Edelman, Mehler & Eichorn, Meat Inspection.
Knoff, Tuberculosis, A Preventable and Curable Disease.
Rosenau, Disinfection and Disinfectants.
Stiles, Prevalence and Geographical Distribution of Hookworm Disease
Hygienic Laboratory, Bulletin Number 10, Washington.
Trudeau, Edward L., An Autobiography.
PART III
PLANT BIOLOGY
CHAPTER XX
TYPICAL FLOWEKING PLANTS
198. Introduction. — The study of plant biology may
begin with any plant. The trees in the park, the grass in
the lawn, and the hothouse
geranium, all respire, use
food, and grow. These
are plant life processes,
and they are similar to
the same life processes in
animals.
199. The Bean Plant. —
We begin the study of
plants with the bean, be-
cause it can be grown in
the laboratory with little
care and because its parts
are easy to examine. The
whole bean plant, Figure
252, is made up of many
parts, the roots which
hold the plant in the
ground and absorb water,
Figure 252. — Bean Plant.
For root details see Figure 261.
•j.v.i
260
TYPICAL FLOWERING PLANTS
Figure 253. — Photograph of Bean
and Pea.
and the stem which supports the leaves, flowers, and
pods. Each of these parts is called an organ, and each
does a given work. While we are learning how the bean
uses these organs, we
shall compare them with
similar organs in other
flowering plants, and in
this way come to under-
stand how all plants of
this kind live.
200. The Bean Seed. —
The bean seed discussed
in this study is the
familiar dry bean, white
or red in color. This
seed contains the embryo or young plant which consists
of three important parts, all inclosed in the seed coat
(testa). These parts are : (1) the
small stem, the hypocotyl (hy-po-kotpl:
Greek, hypo, beneath ; kotyle, cavity) ;
(2) the seed bud, the plumule (plum'ul :
Latin, plumula, feather); (3) the seed
leaves, the cotyledons (kot-y-le'don:
Greek, kotyledon, socket). See Figures
253 and 254.
Every bean is attached at a definite
point to the pod in which it grows, and
a scar, called the hilum (hl'lum: Latin,
hilum, a little body), shows where the Compare with Figure
point of attachment was. Through this
hilum enters all the food material which makes the bean
seed. The testa or coat of the bean is the hard outer
layer, and beneath this may sometimes be seen a delicate
inner layer, called integument These two layers of the
P 3phe
Micropyle
Plumule
Hilum
JAJ /''Testa
Cotyledon
Figure 254. — Parts
of Bean Seed.
THE BEAN SEED 261
seed coat protect the young bean embryo. Other mark-
ings on the outside of the bean are the micropyle
(mi'kro-pil: Greek, micro, small; pyle, gate), a small dol
at one end of the hilum, and the raphe (ra'fe: Greek,
raphe, a seam), a band or ridge which extends Lengthwi
around the bean from the top of the hilum tu the bottom.
The small stem or hypocotol is the part of the bean
embryo that first escapes from the seed coat when tin-
young bean begins to grow. One end of this small stem
soon develops into a root which grows into the groin id.
and the other end develops into a stem which grows
above the ground and lifts the seed leaves into the light.
The seed leaves or cotyledons are by far the largest
part of the bean, and their size is due to the great amount
of food stored in them. They are the parts of tin- bean
seed which are important to man and animals as food.
The seed bud or plumule consists of two small Leaves.
The plumule is connected closely with the food stored in
the seed leaves, which is taken up by the young plant
and used in growing.
LABORATORY STUDY
Place a few beans in dry sand in a warm room. Why do not the
beans grow and sprout? Place others in water in a warm room. What
happens ? Place other beans in moist earth (a) in a warm room ; M in
a cool place. Examine in a few days. These several experiments show
the influence of temperatures, soil, and moisture on the sprout in g of beana
Heat a few beans in an oven for ten minutes and then place them in a
warm, moist soil. Why do they not grow? Soak beans for several
hours. Remove the testa and place them beside dry beans for a to-
days. What happens ? This experiment illustrates one use <<t the testa.
Examine a dry bean. Split it along the bark and observe I) the two
parts into which it divides. These are the cotyledons of the new plant.
Note (2) the pair of small white leaves which are the plumule <>t the new
plant; (3) the hypocotyl, below the cotyledons, from which the stem
and roots will grow; (4) the hard covering or testa. Look for the
micropyle and raphe on a bean not split.
262
TYPICAL FLOWERING PLANTS
Figure 255. — Diagram
of Corn Seed.
201. Corn -'Seed.'' — A grain or kernel of corn, com-
monly called a seed, is like a bean (1) in containing a
young plant, the corn embryo ; (2) in containing food
for the use of the embryo when it first begins to grow ;
and (3) in having marks upon it.
On the top of the kernel is a slight
prominence, the scar which marks the
place where one thread of the so-
called silk was attached. On one
side of the kernel is a depression
beneath which the embryo lies, and
at the base is a stalk by which the
kernel is attached to the cob during
its development (Figure 255).
A corn grain differs from a bean in
being a fruit, — that is, the seed case
adheres to the seed coat as a second
covering. A kernel of corn, therefore, corresponds to a bean
pod containing but one seed. Corn differs from the bean
also in the position of the embryo, which is at one side of the
food supply. The
latter is called the
endosperm (en' do-
sperm : Greek, endo,
within ; sperma, a
seed). Another dif-
ference between the
two is that the corn
has a single modified cotyledon called the scutellum (sku-
tel'lum : Latin, diminutive of scutum, a shield), the
use of which is to absorb and digest the food and carry
it to the embryo (Figure 255). The cotyledon of the
corn never appears above ground. The corn embryo has
its leaves rolled into a tight, pointed bud, which enables
Figure 256. — Sun-
flower " Seed."
A fruit.
Figure 257. — ■
Squash Seed.
CLASSIFICATIOX OF SEEDS
263
it easily to pierce the earth above. The root is at the
lower part of a short hypocotyl.
As the corn has but one cotyledon, it belongs to the
class of plants known as monocotyledons (moii-o-kot-v-lr'-
don : Greek, mono, one ; kotyledon, socket). The bean,
having two cotyledons, belongs to the class dicotyledon*
(di-kot-y-leMon : Greek di, two ; kotyledon, socket).
LABORATORY STUDY WITH CORN
Remove most of the endosperm from a few kernels, and plant them.
How does the growth compare with that of a kernel retaining ;ill its
endosperm? Examine whole corn kernels, noting (1) silk sear on top ;
(2) depression on the side ; (3) hard outer covering; (4) stalk by which
it was attached. Cut crosswise a kernel which has been soaked in wal
and identify the embryo, scutellum, endosperm, and hard outer covering.
Split a kernel lengthwise and find the same parts. Remove the embryo
from another soaked kernel and study its attachment to the endosperm.
Look for the plumule and root.
Examine such seeds as you can obtain and make a report, using the
following table as guide.
Bean .
Pea .
Corn .
Squash
Etc. .
Size
Embryo
EASILY
Seen
IIili M AT
BlDH
llll.t M OS
End
Two
COTJ i.l -
DONS
■ '■ B
COTYl K-
|..,N
202. Classification of Seeds. — The comparative stud\ oi
the bean and corn seeds shows the important parts of seeds
and explains the chief differences between them. The
common seeds are classified as follows : monocotyledons:
grass, wheat, barley, oats, and rye ; dicotyledons : Bquash,
morning glory, tomato, radish, and beet.
264
TYPICAL FLOWERING PLANTS
203. Growth of the Bean Embryo. — As soon as the ground
is warm in the spring, farmers plant beans in rows. After
the bean seed has lain in the damp earth for about ten days,
the moisture has softened the seed coat and food, and the
shoots from the beans begin to show above the ground.
The first part of the bean embryo to show is grown in the
little stem (hypocotyl). This curves sharply into an arch
and begins to push upward through the particles of soil. At
the same time delicate
roots push downward
into the soil (Figure
258). As soon as the
arch of the hypocotyl
has pushed through the
soil into the light, it
straightens up and pulls
the seed leaves (coty-
ledons) out of the
ground. The seed coats
are usually left behind
in the soil. As soon as the cotyledons are exposed to the
light, they crack apart, slowly spread wide open, and in a
few days become green. During these changes in the coty-
ledons, the leaves of the plumule have taken from them
the food stored for the use of the growing bean embryo.
As soon as this store of food is absorbed by the young
bean plant, the cotyledons drop to the ground. The bean
seedling is no longer dependent on the food in the seed,
but is able to gain its food from the soil and air.
During the summer the bean plant grows bean seeds,
and the farmers harvest the beans and store the seeds in
barrels, sacks, or wooden bins. The dry beans may be
kept for years and still grow bean plants at any time
when conditions are favorable.
a
Figure 258. — Germination of Bean.
FOODSTUFFS IN THE BEAN
2IW3
LABORATORY STUDY
Examine germinating seeds and young seedlings »>f various kind
plants, and note their peculiarities in Bprouting as indicated below.
Bean .
Corn .
Pea .
Tomato
Squash
Maple
Etc. .
Ai:< ii
Pkominent
Ai;i li HOI
l'l'.i'MIMN I
Cotyledons
\ BOVK
( litoi N l>
COTYLl l>>'S^
ttO I A l«i\ I
< . BOUND
I i - i \
Brocohi I P
204. Foodstuffs in the Bean. — The bean stores two kinds
of stuffs: carbohydrates and proteins. Carbohydrate is
the name of the foodstuff which includes such foods as
sugar and starch. The term protein is applied to the
foodstuff found in such foods as the lean of meat, the white
of egg, and the curd of milk which we use as cheese.
The presence of these foodstuffs may be shown by
applying the following chemical tests. I >oil beans until
they are soft and then place a small portion of them in a
test tube. Add a drop of iodine. If starch is present,
the mixture will turn purple in color. Add strong nitric
acid to a second portion in a clean test tube, boil and
cool. If protein is present, the mixture will be a clear
yellow color which will become orange if ammonia is
added. To a third portion add Fehling's1 solution as a
i 1. Copper sulphate 9 grams
Water 500cc.
2. Rochelle salts 49 ,i;r;iiii>
Caustic potash 30 grams
Water 250cc.
Take two volumes of l. and one of 2, and add to the mixture 2 rolum<
water. Do not mix 1 and 2 until ready to use.
266
TYPICAL FLOWERING PLANTS
test for sugar. If the latter is present, the mixture will
become dull orange when heated. Test uncooked seed for
oil (1) by heating it over a lamp on a sheet of linen paper ;
(2) by soaking it over night in ether. (This must not be
near a flame at any time.) If oil is present, it will show
on the paper as a clear spot, and in the second test the
oil will appear on the surface of the ether in the test
tube.
Make a record of the results as indicated below:
•
Much
Peotein
Much
Staech
Oil
SUGAB
Bean
Corn
Wheat ....
Walnut ....
Pea
•
205. Digestion of the Food in the Seed. — It may appear
strange that the growing bean plant lives upon the food
stored in the cotyledons, and yet such is the case. But this
food must undergo a real digestion before the bean embryo
can use it. We do not know just how this digestion takes
place in the bean, but in the corn, as we have learned,
there is a special structure, the scutellum, which helps to
digest the food in the endosperm. This corn scutellum
may be removed from the corn seed and made to digest
other kinds of starch, for instance, that obtained from a
finely grated potato. This should be kept warm and
moist for several hours, after which it may be tested for
sugar with Fehling's solution (See page 265). When
scientists learn more about the digestive processes of
plants they will probably find that they are similar to
the digestive processes of animals.
ROOT SYSTEM
2(37
206. The Bean Seedling — Each bean seedling is provided
with a supply of food which gives it a start in life. But
after this supply is exhausted, the young beao must be
able to prepare its own food. The Beveral parts of the
bean seedling are the roots, stem, and leaves, all of which
work in preparing the seedling's food.
207. Root System. — The first root to form on the bean
is called the tap or primary root and grows straight
downward. Many
branches, known as
secondary roots, grow
from the taproot.
These large secondary
roots serve chiefly to
hold the plant firmly
in place. From the
secondary roots smaller
branches or rootlets
grow, and on these, a
short distance back
from the tip, are nu-
merous root hairs.
In order to under-
stand the other great
use of roots, we must
be familiar with their
structure. A cross sec-
Figure 259. — Bean Plants.
All the food these plants have used came
from the cotyledons, as the jar contained
only sawdust.
tion of a taproot shows three regions. In the central part
is a woody portion called the central cylinder. Next i«> and
outside of this is a layer known as the endoderm (Greek,
endo, within ; derm, skin) which separates tin- central
cylinder from the next region, the cortex (hat in, cortex,
bark). Outside of all is a thin protective layer, the
epidermis.
268
TYPICAL FLOWERING PLANTS
If we examine under the microscope a portion of the
epidermis taken from near the center of an onion bulb, we
find that it is made up of many
small parts, called cells. Every
cell consists of living matter
(protoplasm) surrounded by a
wall. Near the center of each
cell is a small spherical body
called the nucleus. See page 4.
All regions of the plant body
are made of such cells, and the
cells of each region are adapted
to the special work of that re-
f-v^^^Sii^^i^^^S sdon. Therefore the cells of a
3miVfB plant body vary in size and
shape, but all the cells of any
one region are nearly alike.
Such a group of similar cells
is called a tissue. See page 5.
A cross section of a taproot
shows the tissues of all the
layers in the plant. The cen-
tral cylinder contains groups
of cells called fibrovascular
bundles. Some of these cells
overlap in such a way that they
make continuous tubes from
the root, up through the stem,
and into the leaves. In the
leaves the vascular bundles are
called veins. The cells which
carry the liquids present in the plant are to the plant
what veins and arteries are to animals. The inner part
of a vascular bundle is made up of woody cells and is
Figure 260. — Sections of
Bean Root.
1, epidermis; 2, cortex;
3, central cylinder.
ROOT SYSTEM
269
nucleus-
epidermal
celiacs
Figure 261. — Root Hairs.
called the xylem. These cells carry water from the root
upwards. The outer part of the bundle (the phlo&m)
is of a softer tissue and contains the sieve vessels which
carry liquid food downward.
The epidermis of the rootlets is covered with rout
hairs, which are really much elongated cells (Figure 261).
While root hairs help to
hold a plant firmly in
place, their main use is
to take up water from
the soil. The cell walls
are thin and are lined
with a thin layer of pro-
toplasm. Water is taken
in through the walls of the cells by osmosis (page 3). The
root hairs which grow in soil apply themselves closely to
particles of it, and take from them the thin film of water
with which each is covered. On this account the hairs or
rootlets grown in soil are much more
irregular in shape than those grown in
water or in moist air. Unless a plant is
removed carefully, all the root hairs are
broken off and remain in the ground.
Another statement is frequently
made in discussing the uses of rout
hairs, namely, that by means of an
acid which they secrete, they dissolve
minerals in the soil so that they can
be taken up by water and carried into
the plant. This is based on the fact that a seedling
grown on a polished marble plate will corrode the sur-
face, and on other experiments. Researches recently
made prove conclusively that root hairs do nut secrete
acid.
Figure 262.
Cap.
Root
270
TYPICAL FLOWERING PLANTS
Rootlets are protected on the end by a structure called
a root cap (Figure 262). This cap is made up of loose cells
which are constantly formed from the inside. As fast as
the outer cells are destroyed by the pushing of the root
through the soil, new cells are ready to take their place.
Small bunches, called
tubercles (Figure 263) are
found on the rootlets
of plants of the bean
family. The tubercles
are filled with bacteria
which gather nitrogen
from the air, use what
they need, and leave the
surplus in the roots.
Some of this nitrogen
is used by the growing
plants themselves, and
any that they do not use
is left in the soil for the
use of other plants.
Most plants take from
the soil more nitrogen
than they add to it, but
the opposite is the case
with beans and their
relatives. Thus clover and other relatives of the bean
are used by farmers as a cover crop or for "green
manure," so called, for the sake of replacing in the
soil the nitrogen which other crops have used up. The
practice of rotating crops depends on the fact that dif-
ferent kinds of plants use different material in the soil. In
successive years crops of different kinds will grow better
than crops of the same kind, unless the soil has been sup-
Figure 263. — Bean Roots.
Showing tubercles.
THE lU.AX STEM
271
Figure 264. — Fibrous Roots of
Buttercup.
How do they differ from the bean roots ?
plied with the used-up ele-
ments through the aid of
fertilizers and chemicals.
When water containing
minerals in solution is
taken in through the root
hairs, it is passed along
by osmosis to the woody
layer of the rootlets and
thence to the primary root
from which" it is distrib-
uted to the parts of the
plant above ground. Here
it is made into food and
carried by the phloem of
the vascular bundle to
all parts of the plant.
The root system of a plant, then, serves two main purposes :
to hold it fast in the ground, and to absorb water from tin-
earth. In passing through the soil this water has taken up
mineral substances which will enter into the plant's food.
LABORATORY STUDY OF ROOTS
Cut a carrot crosswise and lengthwise, and note the centra] cylinder
and cortex. Cut across one of the larger bean roots, noting (1) the cen-
tral woody cylinder ; (2) the softer ring surrounding it; (3) the outer
epidermis. Cut a root lengthwise and find the same tissues. Examine
sprouted barley for root hairs and root caps; also a radish seedling for
root hairs. Stand a cut-off root in red ink for a few hours. Make a
and lengthwise sections, noting what part has been stained by the ink.
This shows the routes through which absorbed water travels.
208. The Bean Stem. — The bean stem is made up of three
parts : (1) a central pith where food is stored ; (2) woody
fiber which conducts water; and (3) a bark and an epidermis
which cover and protect it. The stem aa a whole holds up
272 TYPICAL FLOWERING PLANTS
the leaves to the air and light, carries water and food
materials gathered by the roots to the leaves, and distributes
liquid foods to all parts of the plant.
LABORATORY STUDY OF A BEAN STEM
Make a cross section of a bean stem and find (a) the central pith;
(b) the woody ring surrounding it; and (c) the outer green bark and the
epidermis. Split a stem lengthwise and identify these parts. Stand the
cut-off end of a stem in red ink for a few hours ; then cut across and
lengthwise, noting that the woody tissue is stained red. Compare the
stem with the root.
209. The Bean Leaves. — A bean leaf consists of two
parts : the stalk or petiole (Latin, petiolus, fruit stalk) by
which it is attached to the stem, and the broad, green part,
the blade. Petioles are longer in some parts of the plant
than in others. Where are the longest ones ? What
reason can you give for this?
The blade of a leaf is in three parts, each of which has
a prominent rib entering it from the petiole. From the
rib many small branches extend to all parts of that division
of the blade. The vascular bundles, or veins, are of use
to the leaf, not only in carrying water to it from the root
and food back to the root from the leaves, but also in giving
firm support to the soft parts between them.
A leaf like the bean, which has many small veins running
together, is called a net-veined leaf. All dicotyledonous
plants have leaves with net veins.
A section through the blade of a leaf shows several dis-
tinct parts (Figure 265). The outermost layer is the epi-
dermis, a layer of cells without much color, which serves
as a protective skin. Below the epidermis is a layer of
brick-shaped cells placed on end. These are called the
palisade cells. They contain green coloring matter (chloro-
phyll) which is held in small bodies called chloroplasts, a
THE BEAN LEAVES
273
word meaning color-bearers. The position of the palisade
cells makes the upper surface: of the Leaf firmer than it
would otherwise be. The arrangement of the cells in a
compact layer regulates the amount of light that penetrates
to the interior of the
leaf and helps to pre-
vent undue loss of water.
Below the palisade cells
are the loosely arranged
cells of a spongy layer.
They contain chlorophyll d!
and are exposed to the
oooooooo
spongy layer
chlorophyll
lower epiaer mis
•stoma
air which enters through Figure 265. — Cross Siction of Bean
i
the holes in the lower F*
epidermis. Most of the How many tissues present ?
work of the leaf is done in this green tissue. Because
this tissue lies in the middle of the leaf, it is known as
mesophyll (mez'o-fll: Greek, mesos, middle ; phyllos, leaf).
The holes {stomata) in the lower epi-
dermis are more than mere holes, for they
can become larger or smaller according
to the needs of the plant. Seen from tin-
surface, each stoma is surrounded by two
bean-shaped cells, containing some chloro-
phyll. These cells (Figure -''>") called
guard cells, have the power of absorbing
water to a greater degree than the other
cells of the epidermis. When the guard
cells are full of water, or turgid, the
Opening between them is larger than
when they are almost empty or flaccid. The size of the
openings regulates the amount of air which passes in and
out, and of the watery vapor which passes out.
The stomata are more numerous on the under side of
Figure 266. — Leaf
Skeleton.
Showing net veins.
274
TYPICAL FLOWERING PLANTS
cells of
epidermis
'---stoma
gu-^rd cell
Figure 267. — Epidermis
of Leaf.
leaves which grow with the blades in a horizontal position,
because there the stomata are protected from water which
would interfere with their action. Leaves which are
nearly upright have the stomata on both sides, and leaves
like a water lily that rest on the surface of the water have
the stomata on the upper surface. Stomata are both small
and numerous. A dozen or more
are found in some leaves in a circle
no larger than a period on this
page.
During a season a large amount
of water passes off through the
stomata of any plant. The pro-
cess of giving off this water is
called transpiration. This pro-
cess is unavoidable. The root hairs gather water almost con-
tinuously, and this is carried to the leaf by the fibrovascular
bundles and distributed to the cells. The mesophyll in
the leaf uses the minerals which the water contains, but
it does not use all of the water. This excess is cast off
into the spaces between the cells (intercellular spaces),
which communicate with the outside through the stomata.
Usually the transpiration takes place readily, but if the
outside air is not in condition to take up moisture, the
cells become too full and the excess is passed off through
organs (the hydathodes) at the ends of the vascular
bundles. The drops of water which escape from the ends
of the hydathodes are called guttation drops. Grass blades
and strawberry and nasturtium leaves show such drops
almost every morning in the spring. House plants like
fuchsia or impatiens will produce guttation drops if
covered for a few hours with a bell jar. Cool a portion
of the jar later, noting what happens. Give an expla-
nation of what you see.
WORK OF THE BEAN LEAF 275
LABORATORY KXTKIIIMKN IS
Hold the underside of a geranium Leaf against a cool window pane and
note the moisture which is condensed. Try other leaves in tin- .sun.- way.
With clips fasten a watch crystal to a growing leaf ami seal with vaseline.
Note the moisture condensed. Try the upper side of the saim- lean
Plunge a leaf into water and set the water in the sun. Do small
bubbles appear on the surface of the leaf ? Where ?
Take leaves of the same plant and coat with paraffin one leaf on both
sides, another on the upper side, and a third on the underside. Lay them
aside for a few days. Then remove the paraffin and examine all the
leaves. Which is in the best condition ? Why ?
Examine with a microscope the epidermis of a number of leaves bom
different plants. Note the irregular epidermal cells and the stomata cells.
Are the stomata arranged regularly?
Hold a leaf up to the light and notice the arrangement of the veins
and soft parts. Study a cross section of a fresh leaf and find : (1) the epi-
dermal layer on top ; (2) the palisade layer below it ; (3) the wide, spongy
layer ; and (4) the lower epidermal layer with stomata.
Stand the petiole of a leaf in red ink and observe how the color spreads
through the veins of the leaf.
•■o'
210. The Work of the Bean Leaf. — • As soon as the bean
plant gets its plumule into the air, the pale leaves unfold,
turn green, and increase in size. The stem elongates,
branches, and other leaves appear. Bach of these new
leaves is held out from the stem or branch in a position
which gives the leaf the greatest possible amount of air
and light. The leaves of the plumule begin to be useful
to the plant as soon as they become green. Their work
is most important in the life processes of the plant.
Does the bean plant respire? When an animal respires,
it takes oxygen into the cells of its body ami gives off
carbon dioxide. The presence of this gas is shown by
forcing: the air that comes from the Lungs through a tube
into limewater. The limewater becomes cloudy. This i>
»
a simple chemical test for carbon dioxide.
If a growing bean plant is kept tightly covered under a
glass disk for twenty-four hours and then the inclosed air
276 TYPICAL FLOWERING PLANTS
is forced through limewater, the clear limewater turns
cloudy. Thus it is shown that the bean leaves have given
off carbon dioxide. The only life process which is known
to produce carbon dioxide is respiration. Therefore we
can say that the plant respires and that this life process
in the plant is similar to the same life process in animals.
See pages 3 and 15.
The Manufacture of Food. — The words "manufacture of
food' are often used in connection with plants. This
process may be better understood by comparing it with
the manufacture of some article in a factory. To manu-
facture an article, there must be a building with rooms;
machines, and power to run them ; and various substances,
called raw materials, which are to enter into the finished
product. In addition there must be a supply of water,
pipes in which to carry it, and forces to move it. Be-
sides the finished product, a factory always yields some
waste material. When the product has been finished, it
is usually packed for distribution and stored in a room to
which it is carried on tracks.
In the leaf factory, the cells of the palisade and spongy
layer are the rooms. The machines are chlorophyll bodies,
and the power is furnished by the sun. The raw materials
are water, containing a small amount of mineral matter
obtained from the soil, and carbon dioxide obtained from
the air. The pipes in which the water comes are the
fibrovascular bundles, and the stomata are the places
where the air enters.
The forces which move the raw material are largely
osmosis, capillarity, and the suction caused by transpira-
tion. The materials made are carbohydrates, in the form
of starch and sugar, and protein. Waste material is
oxygen. The material ready for carrying is usually in
the form of sugar. The storehouse may be the stem, the
WORK OF THE BEAN LEAF
277
roots, or the seeds of the plant, and the tracks for carry-
ing the food to the storehouse are the sieve tubes of the
Figure 268. — Germination of a Monocotyledon.
flbrovascular bundles. Part of the carbon dioxide is fur-
nished by the plant's own respiration. The plant takes
from the carbon dioxide all of the carbon, but only a part
of the oxygen, leaving
some of it to be thrown r~\ ft]) "i1!
off as waste.
The waste oxygen
thus set free by the leaf
in the manufacture of
food can now be used by
animals in respiration.
Animals are constantly
setting free carbon di-
oxide which plants must
have if they are to make
food. Animals will never
be able to use up all of
the oxygen in the air so
Figure 269.
Rootlets of Two Corn
Plants.
Showing how they strive for food
and moisture.
278
TYPICAL FLOWERING PLANTS
long as there are plenty of green plants, nor, for the
same reason, will there ever be enough carbon dioxide
to poison animals.
Another vital process
which the leaf shows is
digestion. It is difficult to
explain how the food is di-
gested in plants, but scientists
have proved satisfactorily
that digestion does take place.
After the food is digested,
it is distributed by circula-
tion. In the experiments it
was shown that the plant has
a vascular system, and that
red ink was carried to all
parts of the leaf. Evidently,
then, a plant has circulation.
Food to be used by the
plant cells must not only be
prepared by digestion and
distributed through circula-
tion, but each cell must take
from the sap what it lacks,
and build this food into
living plant protoplasm.
This process is called as-
similation and as a result of
it cells grow, divide, and
grow to full size again,
thereby increasing the size
of the plant.
Summary of the work of the bean leaf : (1) It performs
respiration; (2) it performs transpiration ; (3) it manu-
Figure 270. — Corn Plant.
Showing prop roots.
THE CORN SEED LlSd
J7!»
Figure 271. — Maple Seedlings.
Compare with Figure 274.
factures sugars and starches (a process technically known as
photosynthesis), and proteins; (4; it digests some of tin-
food that it has made ; (5) it assimilates some of the di-
gested food ; (6) by cir-
culation it carries some
of the starch and protein
to other parts 0f the
plant and brings fresh
raw materials into the
leaf; (7) it gives off
waste material in the
form of oxygen.
211. The Corn Seedling-.
— When the corn seed-
ling begins to grow,
its tightly rolled leaves
which form the sharp plumule push up through the soil.
Next the root grows. The primary root, instead of re-
maining the largest, as in the case of the bean, sends off a
number of branches
about the same size a->
itself. Like those of
the bean, these branches
have rootlets and root
hairs. There is little
difference between the
roots of corn and beans
so far as their structure
goes, but corn roots have
neither tubercles imr
nitrogen-gathering bac-
teria. The first Leaves
Figure 272.- M.crophotograph of of (',,rn :m' likr tl"' lilt,'r
Corn Stem. ones, except in size, be-
hard rind "
: ifi b
ro-vascular
bundles
£
>»
'■ '
<*rJ
\ ■
J> 'U
\ •
\
'4
280
TYPICAL FLOWERING PLANTS
cause only the plumule comes above the ground. The
kernel of the corn remaining in the ground shrinks as the
plant grows and as the food is used. The modified coty-
ledon (scutellum) dies when it has served its purpose of
Figure 273. — Stem of Corn.
Showing node and fibrovascular bundles.
transferring to the young seedling the food stored in the
endosperm.
212. The Root System of Corn. — There are many fibrous
roots of small size, which extend to a distance of several
feet in every direction. Besides these underground roots,
the corn plant has aerial
roots growing from the
lower joints of the stem,
and these are known as
prop roots. These roots
are stout, straight, some-
times green, branching
in the soil. They serve
to hold the plant firmly
in the soil.
213. The Corn Stem. —
While the roots of the
bean and corn are similar
in structure, there are
several differences in the stems of these plants. The corn
stem has no central region filled with pith, but the pith
makes up the greater part of the interior. Scattered
through it are stringlike parts, fibrovascular bundles,
Figure 274.
-Elm and Older Maple
Seedlings.
THE CORN LEAF
I'M
Figure 275. — Seedlings.
a, Horse-chestnut seedling ; b, Honey
locust.
each consisting" of xvlem
and phloem, but not
arranged in any regular
order (Figure 273). Sur-
rounding the pith is a
hard rind which gives
the plant stiffness. The
place where a leaf joins
the stem is called a node.
Some of the vascular
bundles of the stem pass
out through the nodes
and as veins continue on
into the leaves. The
corn stem represents the
structure of all monocotyledonous plants, as the bean stem
represents all of the
dicotyledons which live
only one season.
214. The Corn Leaf.—
The leaf of the corn
has no petiole, but is
attached to the stem
by a clasping lias.-.
This base protects the
•tenderest part of the
stalk, which is just
above the node. At
the point where the
clasping pari and the
blade of the leaf meet,
there is a collar which
prevents water from
running down inside
Figure 276. — Older Horse-chestnut
Seedlings.
Note the palmately compound leaves.
282
TYPICAL FLOWERING PLANTS
the clasping base. The corn leaf is long and narrow ; it
curves, and has wavy edges. Veins run from the base
to the tip without branch-
ing, giving the parallel
venation characteristic
of the monocotyledons.
A cross section of a
corn leaf shows that it
has the same structure
as the bean leaf. The
stomata are aided in pre-
venting undue transpira-
tion during dry, hot
weather by the tight
rolling of the leaf.
215. Other Seedlings.
— All dicotyledonous
plants are like the bean
in having two cotyledons, but differ in other respects.
Peas, for instance, do not bring their cotyledons above
ground. Morning glories have their cotyledons folded in
the middle ; maple seed-
lings have theirs folded
on each other. Many
seedlings have leaves
which differ in shape
from those of the mature
plant (Figure 271).
All monocotyledonous
plants are alike in hav-
ing only one cotyledon
which usually remains in
the soil during germina- Figure 278. — Roots of Radish.
tion. The first seed- Containing stored-up food.
Figure 277. — Wheat Seedlings.
a, grown in sunlight ; b, grown in
the dark.
OTHER BOOTS
283
ling leaves look more
like the later ones than
in the dicotyledons.
216. Other Roots. — All
roots serve to hold the
plant in place and to
collect water. Some
roots have other uses in
addition. The roots of
beets, turnips, carrots,
parsnips, and radishes
store up food the first
Figure 279.
A valuable food.
- Roots of Beet.
See also Figure 296.
year of their growth. If, however, they are planted a
second year, they use the stored-up food to produce fruit
and seeds (Figures 278 and 279).
Ivy has two kinds of roots, one in the ground, the other
Figure 280. — Alfalfa Root.
Compare with Figures 269, 281. and 283.
284
TYPICAL FLOWERING PLANTS
along the sides of the stem to help the plant cling to its
support. Roots which grow in the air are called aerial
(Latin, aer, air) roots (Figure 281).
Sometimes roots arise from the bottom of a stem which
has been cut or broken from the main plant, as in the case
of a geranium slip. Such roots are called adventitious.
The willow is a tree which is
easily grown from a twig, be-
cause it readily forms adventi-
tious roots.
Most roots grow downward
in soil which is well cultivated.
The stimulus which causes them
to take this direction is gravity,
or as scientists say, they are show-
ing geotropism (ge-6t'r5-pizm :
Greek, ge, earth ; tropos, a turn) .
Other influences governing
the direction in which roots
grow are the presence of water
and obstacles. When a root
turns in the direction which will give it the best supply
of water, it is exhibiting hydrotropism (hi-drot'ro-pizm :
Greek, hydro, water; tropos, a turn). When a root
turns aside to avoid an obstacle it acts in response to
the stimulus of touch or contact, showing thigmotropism
(thig-mot'ro-pizm: Greek, thigmos, touch ; tropos, a turn).
The roots of poplar, willow, and soft maple trees, in seek-
ing water, often clog sewer pipes by filling them with
rootlets after they have gained an entrance through a
joint, a habit which renders them objectionable as shade
trees.
In agriculture, the soil is made fine and porous to help
the roots of plants get food and moisture.
Figure 281. — Aerial Roots
of Ivy.
OTHER STEMS
ln:>
LABORATORY WORK ON ROOT8
Test the roots of beet, carrot, parsnip, radish, and turnip with iodine
for starch ; with Fehling's solution for sugar; with nitric acid for protein.
Examine a large number of roots and report.
Dandelion
Plantain
Carrot .
Dahlia .
Corn
Ivy . .
Roots All
Ondbr-
GBOTJND
Roots not
A i.i. Dndeb-
GBOCND
l'l'.IMARV
Kooi -
FlBBOl -
Booi -
I A I.
BOOTB
217. Other Stems. — The stems of all plants are like the
stem of the bean in the work which they do, but some
stems have additional uses. The stems of such plants as
Solomon's seal, dogtooth violet, and Jack-in-the-Pulpit
store up surplus food. These stems are thick and fleshy,
and remain underground from
year to year. For this reason
they are often mistaken for
roots, but they can always be
Figure 282. — Potato.
The eyes are buds.
Figure 283. — Dahlia "Roots."
An underground stem which stores food.
286
TYPICAL FLOWERING PLANTS
^^^^.
^x^^H
[ V ip
« 1
1 \ ^
■«► «# fl
Figure 284. — Microphotograph of
Sunflower Stem.
recognized as stems by the buds of new leaves, or the scars
of former leaves. Underground stems, called rhizomes
(ri'zom) or rootstocks,
send up aerial stems
which live through one
season.
Stems like the water
lily, which grow in
water, have large air
spaces to carry air to
the roots that lie in the
mud at the bottom of
the water.
The trunks of trees
are stems. In evergreen
trees (pine, spruce, etc.)
the trunk puts out
branches, but does not divide, and tapers from base to tip.
Such trunks are called exeurrent (Latin, ex, out ; curro, to
run). In the case of the
elm tree and many others,
the trunk itself divides
again and again. Such
a trunk is called deliques-
cent (Latin, de, from ;
liquescere, to become liq-
uid).
An interesting com-
parison is that between
the climbing and twining
stems of plants, especially
vines, and the sturdy
trunks of trees. The
morning glory is a plant Figure 285. — Cleft Grafting.
OTHER STEMS
2S7
Figure 286. — Whip Grafting.
which twines around some support and thus is able to gel
sunlight for its many leaves. Twining plants of the same
kind always curve in the same direction. In twining
around any object they
touch, climbing plants
are responding to thig-
motropism.
The wild grapevine is
a plant which climbs to
the top of trees by
means of a long, leaf-
less stem. Such plants,
common in the forests
of tropical countries, are
called lianas.
Woody stems have a
structure which differs
from that of the soft bean stem. On the outside is the
brown bark in which are lenticeh, holes which allow air t<>
enter. Under this is a layer of green bark, the out» *r
edge of the phloem of the vascular bundles. Between the
phloem and the xvlein of
each vascular bundle is a
region of rapidly dividing
cells, which is called the
CCDnhilUH, When the \ as-
cular bundles are crowded
close together the cam-
bium of adjoining bundles
touches, thus forming a
ring around the tree (Figure 284). The outer edge of this
cambium layer is always turning to phloem, and the
inner to xyleni.
A woody twig like the horse-chestnut (Figure 290) has
Figure 287.- — Budding.
288
TYPICAL FLOWERING PLANTS
:^=~
Figure 288. — -Twining
Stem of Dodder.
Figure 289. — Creeping Stem of
Trailing Arbutus.
a bud at the end called a terminal bud, and along the branch
are other buds, named lateral buds. These buds are
covered with scales and contain the leaves of the next
season arranged in a definite manner. Sometimes buds
Figure 290. — Horse-chestnut.
OTHER STEMS
289
Figure 291. — Types of Twigs.
a, maple; b, elm; c, walnut; d, catalpa
e, ash ; /, linden.
contain both leaves and
flowers. As a bud
opens, the scales drop
off leaving on the twig
scars crowded together
in indistinct rings. The
growth of a twig in the
preceding year can be
seen by noting the dis-
tance between the tip of
the twig and the first
group of indistinct rings,
which marks the posi-
tion of the terminal bud of last year. A study of the
buds on a branch shows where the new branches will form.
The place where the leaves of last year were attached
shows on the bark as scars, called leaf scars. In each leaf
scar are a number of small dots. These dots are the ends
of the vascular bundles
which grew from the
stem into the leaf.
A cross section of a
woody stem shows a
central pith surrounded
by one or more rings
Figure 292. — Cherry Twigs.
Leaf buds and fruit buds.
Figure 293. — Sections of
Woody Stem.
of wood. The pith and the bark are connected by narrow
lines of pith called medullary rays (Figure i?(.*3). A
290
TYPICAL FLOWERING PLANTS
4 V 4ij=p >J.;»Jf
woody layer examined under a microscope
shows large cells on the inner side of each
layer, and smaller, thick-walled cells on the
outer side. The large cells are formed
when conditions are favorable to rapid
growth, and the smaller cells when condi-
tions are less favorable (Figure 294). A
dry season may check growth during the
middle of the summer so that an indistinct
rinsr will occur between two distinct ones.
This makes it impossible to tell accurately
the age of a tree by counting the rings.
Every part of the woody stem has a
distinct use. The bark protects the tender
growing parts within. The xylem carries
water containing food materials from the
roots to the leaves, and the phloem carries
to other parts of the plant for use or for
storage the food which has been made from
the raw materials. As the stem increases
in thickness, only the outermost layers of
xylem continue to carry water, for the inner
layers fill up with a sub-
stance which hardens
into wood. Although
they are dead, these
layers are still of use in
giving stiffness to the
tree. The work of the
tree goes on without
them, as is shown when
a tree decays in the cen-
ter. The pith in the
center of a tree and in
Figure 294. —
Wood of Spruce.
Greatly magni-
fied.
WiL
Figure 295.
Photograph of Sections
of Wood.
OTHER STEMS
L>(.)1
the medullary rays serves as a storehouse for food and
as lateral conductors of sap.
Liquids are always passing along the paths indicated,
but this process is observed most readily in the spring
when the sap runs from
the broken end of a
branch. When the
leaves are grown, much
of the water carried to
them is lost by transpira-
tion, and little is left to
be carried back. In the
spring, water is carried
down, as well as up.
Most of our common
lumber is made by saw-
ing the trunks of trees
lengthwise. Sawing in
this way shows the
annual rings as long lines (Figure 295), but does not show
the medullary rays except in a few boards. Lumber t<> be
used in furniture is often cut so as to show as many med-
ullary rays as possible. The rays are lighter in color and
more glistening than the woody layers.
A tree grows by adding a layer of new wood each year.
The branches of the current season have only a single ring
of wood, while those of the season bet ore have two rings,
and so on.
LABORATORY STUDY OF TWIGS
Examine a twig from a horse-chestnul tree, and identify 1 1 the termi-
nal buds; (2) lateral buds; (8) leaf scars ; (4) dots in leaf
(5) rings; ((>) scales covering buds; (7) breathing pores or lentta
Dissect a bud to see what it contains. Make a cross Bection of a stem
and find (1) the pith ; (2) woody rings; (3) bark in two layers.
Figure 296. — Food Storage.
Creeping stem of Canada ginger.
292
TYPICAL FLOWERING PLANTS
Figure 297. — Celery Plant.
Compare with Figures 279 and 282.
Figure 299. — Twining Petiole
of Clematis.
Figure 298. — Cabbage Plant.
Figure 300. — Twining Petiole
of Nasturtium.
OTHER LEAVES
293
Examine, with a microscope, a section of wood, looking for the pith,
medullary rays, and annual rings. Examine the boards in the room and
furniture to find the annual rings and medullary rays.
REPORT OX TWIGS
Record your observations in a report.
00
a
-
*-*
O0
-
00
Q
D
pq
<
K
M
i.
-
-
-
—
H
_
SB
-
O
-
i
oo
-
-<
—
■
-
-
-
-
_
•<
O
W
CO
o
£
-
-
.
O
■A
©
O
H
z
w
7.
W
-
Y.
<
<
c
ao
r"
H
H
Z
O
O
— 0
H
0
r.
<
H
■i.
P
i.
M
w
7.
-
00
-
H
h3
:
z
-
-
-
-J
i
-
M
>
/
_
-
6
H
Z
-
►3
—
-
:-
7
/
-
-
-
Geranium .
Horse-
chestnut .
Lilac . .
Maple . .
218. Other Leaves. — All leaves have the same work to
do as the leaves of the bean, but some leaves have other
Figure 301. — Barberry Leaves.
Showing how a leaf may become a thorn.
work in addition. The storage of food is one additional
task. Celery and rhubarb (pieplant) store food in the
294
TYPICAL FLOWERING PLANTS
thick, fleshy stalks of their leaves. In
cabbages, the blade of the leaf is the
place of storage, while in onions it is
the thick enlarged base of the leaves.
Clematis and nasturtiums climb by
twining the petioles of their leaves
around a support.
Pitcher plants have leaves which hold
water and entrap insects. Venus's fly-
trap and sundew both use their leaves to
catch insects.
Plants which have leaves lasting more
than one year are called evergreen; and
those that shed their leaves every autumn
are called deciduous (Latin, deciduus,
falling off). The blade of some leaves
is in one piece, as is the case with the
geranium. Such leaves are called simple
leaves to distinguish them from the com-
pound leaves, like the rose or horse-chestnut, in which one
petiole supports several leaflets.
j****'^
M
I
($"
■
Figure 302. — Pea
Plant.
Leaves modified in-
to tendrils.
Figure 303. — Leaf of Oak.
Simple leaf.
Figure 304. — Leaf
of Elm.
Simple deciduous
leaf.
LABORATORY STUDY
295
LABORATORY EXPERIMENT TO PROVE THAT LEAVES
GIVE OFF WATER
Wrap in waxed paper a jar containing a small plain, and cover the
earth with half an inch of melted paraffine to prevent evaporation.
Weigh the plant each day and note the amount of water l<»st by transpir-
ation through the stomata.
LABORATORY STUDY OF LEAVES
Examine as many leaves as possible and record the facts which yon
have learned about them in a report like the following :
Leaves
Simple
Lb A VK8
Compound
] ) K< 1 1 1 1 • ■ 1 -
Stoeaoi
< LIMBING
Cherry .
Maple
Lilac . .
Ash . .
Rose .
Horse-
chestnut
.
Etc. .
219. Comparison of a Monocotyledonous with a Dicotyledonous
Plant. —
Monocotyledon
Dl< OTV LEDOM
Corn
r.KAN
Epidermis.
Same structure.
Cortex.
Root.
Endoderm.
Central cylinder.
Root caps.
.Root hairs.
Hard outside.
Thin epidermis in young plants.
bark in <>M.
Much pith.
Pith confined to center and med-
ullary rays.
Stem.
Scattered vascular
bundles, no cam-
Vascular bundles form rinp,
phloem out. xylctn in. cam-
bium.
bium between.
Vascular bundles
Vascular bundles pass to
uiven off from
branches and to leave 3.
1 nodes,
to leaves
•
296
TYPICAL FLOWERING PLANTS
Monocotyledon
Corn
' Long, simple, and nar-
row.
Leaves. < No petiole, but clasp-
ing base.
Parallel veins.
Dicotyledon
Bean
Broad, compound.
Petiole.
Netted veins.
220. The Bean Flower. — Just before the bean plant reaches
full size, greenish buds appear in clusters on the ends of
the branches. These green buds grow into the bean
flower. This flower is made up of a number of parts, all
of which have an important work to do in producing the
bean seed.
The parts of the bean flower have technical names which
it is necessary to learn in order thoroughly to understand
flowers. The green,
outermost part, called
the calyx (Greek, kalyx,
cover), is made up of
separate sepals (Latin,
separ, separate) which
form a cup in which the
rest of the flower is
fastened. The calyx
protects the delicate
parts of a flower while
they are small. Within
the calyx is the white
and much larger part
called the corolla- (Latin, corolla, crown). The corolla
(Figures 305 and 307) is made up of irregular shaped struc-
tures called petals (Greek, petalon, leaf) ; within the corolla
there is a group of stamens (Latin, sto, stand) which are
recognized easily by their slender stalks, filaments, and
enlarged tips or anthers. At the exact center of the bean
Figure 305. — Diagram of Bean Flower.
THE BEAN FLOWER
297
flower and within the group of stamens is the pistil. Tin-
stamens and pistil are the important parts <»l' the bean flower
because they produce the bean seed (Figures 306 and 307).
The stamen bears in the enlarged tip many minute bodies
which are known as pollen or pollen grains
(Latin, pollen, fine flour). The pistil is
divided into three parts: (1) a slightly ex-
panded and sticky tip, the stigma (Greek,
stigma, point); (2) a slender portion con-
necting the stigma with the much larger base,
the style (Greek, stylos, pillar) ; (3) and the swol-
len base, the ovary (Latin, ovum, egg~). See
Figure 306. The ovary contains small, rounded
bodies called ovules which ripen into seeds.
The bean flower is a complete flower, be-
cause it has all of these parts: calyx, corolla,
stamens, and pistil. It is also said to be
perfect because it contains in the same flower
the two organs needed to produce seeds, the
pistil and stamens.
The word pollination is used to describe the
carrying of the pollen from the anther of the
stamen to the stigma of the pistil. This may
be done by the wind, by insects, or by the
contact of a stamen with a stigma. The bean
flower secretes a sweet fluid, nectar, at its base,
which is the fluid the bees gather to make in t « »
honey. When a bee alights on a bean flower, it pushes
its head among the inner parts to get the nectar. In
withdrawing its head, pollen is brushed off and the hairy
body of the bee, especially the head, is covered with it.
When the bee puts its head into the nexi bean flower,
some of this pollen is caught by the sticky stigma past
which the bee has to push to get the nectar. Thus the
Figure 306.
— Diagram
of Stamen
(above) and
Pistil (be-
low).
298
TYPICAL FLOWERING PLANTS
stigma is covered 01
pollinated with pollen
from the stamens of
another flower, and the
first step is taken which
results in the formation
of a bean.
221. The Corn Flower.
— The flower of the
corn is imperfect, for it
lacks one of the two
parts necessary to make
a seed. Both parts, however, are found on the same plant,
the stamens in the " tassel " (Figure 270) at the top of the
stalk, and the pistils on the " ear " (Figure 310) at the side
Figure 307. — Sweet Pea Flower.
Figure 308. — Fly Pollinating Wild Carrot.
FERTILIZATION
2\)W
Figure 309. — Swallow-tail Butterfly
Pollinating Persian Lilacs.
of the stalk. The style of each pistil protrudes from the
ear of corn as a long green thread, called the silk. The
pollen is light and abun-
dant, and falls from the
stamen with every stir
caused by the wind.
The stigma at the end
of the style is sticky,
as in the bean. In a
field of corn where
many plants are shed-
ding pollen at the same
time, it is almost certain
that every pistil will
receive at least one
grain of pollen. It is to secure thorough pollination that
corn is planted in fields, with the plants close together.
Plants which have both sta-
mens and pistils on them, but
on different flowers, are called
monoecious (mo'ne'shfis : Greek,
monos, one ; oikus, house). Plants
which have only staminate or
only pistillate flowers are calif 1
dioecious (di-e'shus: *//. twoj
oikus).
222. Fertilization. — The second
step in the production of a ^'kh\
is fertilization. By this we mean
the union of the sperm DUCleUfi
of the pollen cell ( male parent )
with that of the egg cell in the ovule (female parent ).
The pollen grain has two coats, an outer ami an inner.
The outer is thicker than the inner, but it has thin spots
Figure 310. — Corn Flower
with Pistils.
300
TYPICAL FLOWERING PLANTS
in it. When a pollen grain falls on a sticky stigma, the
inner coat pushes out through one of the thin places,
forming a tube into which all the contents of the pollen
grain flow. The contents, at this time, consist of two
nuclei and a small amount of protoplasm. The pollen
tube grows and pushes its way through the loose tissue
of the stigma till it reaches the ovary containing the
ovules (Figure 311, a, 6).
The ovules are attached to the
sides of the ovary. Each has a
Figure 311. — a, pollen grains growing
through pistil ; b, same magnified ;
c, nuclei of pollen and egg.
thick coat called the integument which does not quite meet
at one spot, known as the micropyle. Inside the ovule is
the embryo sac containing the egg cell and a few other cells.
When the pollen tube reaches the micropyle of an
ovule it enters, touches the egg cell, and bursts. The
male nucleus unites with the nucleus of the egg, and fer-
tilization is accomplished (Figure 311, c). The other nu-
cleus of the pollen tube usually unites with a nucleus
near the center of the embryo sac and helps to form tissue
which may be of use to the growing embryo or may form
a part of the mature seed.
The fertilized egg cell soon begins to divide and grow, and
OTHER FLOWERS
:-;i ) l
finally it develops into
the embryo, consisting
of plumule, hvpocotyl,
root, and cotyledons.
The integument changes
to testa, food is stored up
for the embryo, and the
seed is ripe, ready to start
a new ijlant, although it
may have to wait for
vears before conditions
allow it to sprout.
223. Other Flowers.—
Flowers like the bean
which have all the parts usually found in a flower — sepals,
Figure 312. — Pistillate and Stami-
nate Flowers of Willow.
0&
Figure 313. — Violet.
a, cleistogamous flowers.
302
TYPICAL FLOWERING PLANTS
petals, stamens, and pistil — are complete. As we have seen,
they are also perfect because they have in the same flower
stamens and pistil, the parts necessary for the production
of seed. An imperfect flower may be staminate, having
only stamens, like the tassel of the corn, or pistillate, hav-
ing only pistils, like the ear of the corn (Figure 312).
So an incomplete flower may lack either sepals or, as is
more common, petals. Hepatica is an example of a flower
which lias no petals, but its sepals are colored.
Regular flowers are those in which all the parts of the
same kind are the same size and shape, as in the blossom
of the apple. In irregular flowers all the petals or sepals
are not of the same shape. The bean is an irregular
flower, and so is the violet.
Cleistogamous flowers (klis-tog'a-mus : Greek, klistos,
closed ; gamos, marriage) are found in the violet (Figure
313) and pansy in addition to the flowers of the ordinary
type. These are formed underground near the surface,
have no colored parts, usually only one stamen, and they
never open. They produce many seeds, however.
FIELD AND LABORATORY STUDY
Study flowers in field and laboratory, and record the results, using the
following table as guide.
Geranium .
Castor bean
Salvia . .
Nasturtium
Pansy .
Etc. . .
O 1=
o K
— —
- -
Corolla
Lacking
Stamens only
in a Flower
Pistils only
IN a Flower
X
X
X
c ~
■J w
Carolus Linnaeus (ihe Latinized form of the name Karl von
Linne) was born in 1707 and died in 1778. He was a celebrated
Swedish botanist and naturalist.
Linnaeus went to the University of Upsala in 1728, attracted
by the fame of Rudbeck, the Professor of Botany, whose assistant
he became.
In 1732 he explored Lapland. Later, while studying in Holland,
he wrote works on botany which attracted wide attention. In
1741 he became Professor of Botany at Upsala, whither his fame
attracted students from many foreign countries. Linnaeus' sys-
tem of plant classification greatly promoted the study of botany
in his day.
OTHER FLOWERS
303
Figure 314. — Two-parted Flower
of Mint.
Note the convenient place for the bee
to alight ; b, stamens in usual position ;
c, stamens bent down by bees. Pollen
will be shaken on to the bee and carried to
another flower.
The classification of
plants by stamens and
pistils was originated by
Linnaeus, the usual name
given to Carl von Linne
(1707-1778), the Swed-
ish botanist. During
the period of his studies
many new plants were
beinsr brought to the
attention of botanists
by the traders who were
constantly penetrating
to parts of the world
hitherto but little
known. In 1737 Lin-
nams published his
famous book, G-enera Plantarunu in which he gave special
names in the nomenclature of plants, and also first
enunciated the principles of defining general species and
the use of specific names.
For his achievements
in the field of botany
Linnaeus was elevated
to the nobility.
Flowers are also classi-
fied according to their
method of pollination,
that is, whether by in-
sects or by the wind.
Insects have an objecl in
visiting flowers, for in
Figure 315. — Lady Slipper. them they find the
Pollinated by insects. nectar which tliey make
304
TYPICAL FLOWERING PLANTS
into honey, or they find pollen, which they eat and feed
to their young. Insects are attracted to flowers by their
strong odor or bright colors, or by both.
One of the most interesting studies in biology is the
relation which exists between certain flowers and the
insects which pollinate them. In the case of salvia or
flowering sage, for example, the ir-
regular corolla offers the bee a con-
venient place to alight. To suck up
the nectar the bee must push its head
into the cup of the flower where it is
forced to brush against the stigma
which becomes covered with the pollen
from the last salvia flower which the
bee visited. When the bee withdraws
its head it becomes dusted with pollen
from the anthers which bend down
and touch the back of the insect.
The stamens and pistil of salvia do
not mature at the same time (Figure
317), so that the bee can carry pollen
only from flowers in which the stamens
are ripe ; and the pistil will receive
pollen only in the flowers that have a
ripe pistil.
Certain orchids have deep tubes
from which the nectar can be drawn
only by insects like large moths which have long sucking
organs. Many orchids have their pollen in masses.
These masses stick to the head of the insect visitor,
and hang down while it is passing to another flower.
In this position the mass is almost certain to be rubbed
off on the stigma of the second flower. Red clover
is dependent on bumble bees for pollination, for they
Figure 316. — Flower
of Columbine.
Showing spurred
petals. Only a long-
tongued insect can
reach the nectar. Note
the bunch of stamens
upon which the insect
alights.
POLLINATION
:m
have a tongue of the length to get the nectar. The pollen
is carried as in the case of the bean.
Flowers which are pollinated by wind have no need of
color or of odor, but they have pollen which is Light,
abundant (for much of it is lost), and easily shed from
the anthers. The stigma is feathery, thus offering more
surface for the grains of pollen. Grass and corn, as we
have seen, are examples of flowers pollinated by the wind.
It is an advantage in securing proper pollination for such
plants to grow close together.
LABORATORY STUDY
Pollination of Flowers. — As soon as flowers come, observe them
closely and note which have many insect visitors, and which few or Done.
Fill out a report as suggested below and add any points which int<
you further.
1
E-
fc>
V.
XI
o
H
<
L-
t>
C5
*
n
O
fa
an
Z,
O
O
es
o
ao
O
o
o
a
S5
O
PS
H
«
55
O
M
H
n
O
3
n
Z
si
<
V.
-
H
O
>
<
00
:
-
00
00
-
-
H
oo
R
-
-
o
►4
OS
Q
O
o
<
—
o
o
0
z
C
£
H
Sweet pea .
Dandelion .
Hepatica
Buttercup .
224. Cross- and Self-Pollination. — All plants which re-
ceive pollen from another plant of the same kind arc said
to be cross-pollinated. Darwin found that {»lants which
grow from seeds resulting from cross-pollination produce
a greater number of seeds and that these seeds have more
vigorous embryos than those resulting from self-pollina-
306
TYPICAL FLOWERING PLANTS
tion. Since this has been known, nursery men and gar-
deners have taken advantage of cross-pollination to
improve their stock
and to produce new
varieties of fruits and
vegetables. Much of
Luther Burbank's
wrork has been based
on cross-pollination.
Plants have a num-
ber of devices for pre-
venting self-pollina-
tion. The anthers,
for instance, may be
turned away from the
stigma ; or the pistil
may be so tall that
no pollen can get on
it from the stamens of the same flower; or the stigma
may be ripe and the ovules started to develop before
the stamens of the flower are ready to shed their pollen
(Figure 317).
While it is the rule that plants avoid self-pollination and
self-fertilization, a few have no other way of producing
Figure 31 7. — Salvia.
A flower in which the stamens mature at
one time and the pistils at another.
Figure 318. — Easter Lily.
seeds. This is true of cleistoofamous flowers. The one
or two stamens which they develop contain sufficient
POLLINATION
307
pollen to fertilize all
their ovules, for none
is lost, and the pistil
and stamen are placed
in such a position that
pollination is sure to
occur.
Other plants, as some
of the lilies, are ar-
ranged for cross-ferti-
lization, but if that fails,
they can pollinate them-
selves. An Easter lily
at first keeps its three-
parted stigma carefully
closed until it is well
out of the way of the
anthers (Figure 318, a).
Then the stigma opens
out, exposing its sticky surfaces to the air and to insects
which may visit the flower (Figure 318, h ). If no pi 'lieu is
brought to the stigma, however, the plant brings the pistil
up until the stigmas almost touch some of its own anthers
Figure 319. — Fruit of the Bean.
A pod.
Figure 320. — Fruit of the Corn.
Kernels or grains.
308
TYPICAL FLOWERING PLANTS
dry
capsule
from which pollen is received
for the fertilization of the lily's
own egg cells in the ovules
(Figure 318, c).
225. The Fruit of the Bean and
Corn. — In science the term fruit
includes much more than the
meaning we usually give it when
we refer to apples, oranges, or
berries. By fruit the botanist
means the ripened ovary of a
plant and its contents. The
first step in the production of
fruit is the pollination of the
stigma of a flower. Next comes
the fertilization of the egg cell
in the ovule. Finally the ovule develops into a seed, and
at the same time, the ovary grows to protect and to pro-
vide nourishment for the
seed until it is mature.
In the bean plant the
pod begins to develop
from the pistil as soon as
fertilization has taken
Figure 321. — Fruit of the
Poppy.
A capsule.
sepals
Figure 322. — Capsule of
Violet.
Figure 323. — Chestnuts.
A dry fruit.
OTHER FRUITS
309
place. Each ovule remains attached to the pod until the
former changes into a seed and becomes mat inc. In bean
pods and string beans, ovules are often present which have
not developed owing to a lack of ferti-
lization of the egg cell. When a bean pod
is ripe, it splits and sometimes curls up,
thus helping to scatter the seeds. From
seed to seed again makes up the life his-
tory of the plant.
In the corn, as in the bean, each ovule
develops into a grain of corn, if the egg
cell has been fertilized. The ovary ad-
heres so closely to the egg cell that it
cannot be seen as a separate organ like
the pod of the bean. All the maturing
grains of corn receive nourishment through
the cob to which they remain attached, and they are pro-
tected by the modified leaves or husks. Undeveloped
ovules are sometimes found in ears of corn.
^vA
/A
l>'\
-
•
Figure 324. —
Dry Fruits.
a, beechnuts ;
b, acorn.
Figure 325. — Vertical Section of
Apple.
A pome.
Figure 326.- Cross Section
of Apple.
A pome.
226. Other Fruits. — The ripened ovary and its contents
take many forms, so that we have the fleshy fruits, such
310
TYPICAL FLOWERING PLANTS
Figure 327.
■ Cross Section of Orange.
A berry.
as the apple, or dry
fruits, like the bean.
Pods and other fruits
which open in a definite
way are called dehiscent
(Latin, dehisco, to split
open) fruits. Poppies,
pansies, and violets have
dehiscent fruits called
capsules. Nuts, corn, and
wheat are examples of
indehiscent fruits (Fig-
ures 323 and 324).
Fleshy fruits fall into
three groups : (1) pome
fruits, apples and pears which have the seeds in a core in the
middle surrounded by a thick, fleshy part (Figure 325);
(2) drupes, or stone fruits represented by the plum, which
has the seed inclosed in a hard stone surrounded by soft
pulp; and (3) berries, fruits in which the seeds are scat-
tered through the pulp, as in
the grape, currant, or orange
(Figure 327). Most of the
fruits commonly called berries
are really collections of small
drupes. In the strawberry each
" seed " is a fruit, and the fleshy
substance is the receptacle of
the flower, which has been
greatly enlarged. In the case
of the blackberry, as well, the
receptacle is eaten, for the drupes
cling- to it as it is removed from
& Figure 328. — Forms of Dehis-
the bush. Melons, cucumbers, cent Fruits.
SEED DISTRllirTlOX
:m
Figure 329. — Fruits with Hooks.
Distributed by animals.
pumpkins, and squashes
are a special kind of
berry called pepo. Such
fruits have a hard rind.
The use of fruits to
plants is simply to pro-
tect the seeds while they
are maturing, and to
secure their distribution
later. But the fruits of
the cereal grains and of
beans furnish the highest form of vegetable food for man
and domestic animals. The fleshy fruits, on the other
hand, furnish many of man's luxuries in the way of food.
One of the most interesting studies about plants is how
their fruits may be improved by supplying the best possi-
ble conditions for their growth; how their flavor may be
improved, the skins made thicker or thinner, t lie seeds
grown larger or smaller,
or such other chang
made as to cause the
fruits to be more de-
sirable to man. Many
of these changes may be
brought about through
cross-fertilization.
227. Seed Distribution.
— Seeds must be scat-
tered or distributed to
" spread " the plant, and
the fruit helps to do
this. It' all the seeds
merely fell to the ground
Figure 330.— Burdock in Blossom. and germinated there,
312
TYPICAL FLOWERING PLANTS
Figure 331. — Fruits Distributed
by Wind.
but little range would
be added to the plant's
territory, and a small
increase in the number
of plants would take
place. Such plants as
the dandelion and bur-
dock have developed the
most successful means
for gaining the distri-
bution of seed, and
are, therefore, the most
common and most widely distributed.
Seeds may be distributed by an explosion of the fruit
case or through the agency of the wind, water, or animals.
Some plants, like the witch-
hazel or jewel- weed, have a fruit
the tissue of which is so strained
at the time of ripening that the
seed case bursts with an explo-
sion which throws the seeds some
distance from the parent plant.
Figure 332. — Other Fruits
Distributed by Wind.
a, catalpa ; b, dandelion ;
c, milkweed.
Figure 333. — Fruits and Seeds.
SEED DISTRIBUTIOX
313
Frequently plants de-
velop special structures
which help to secure the
distribution of seeds
through the agency of
an animal. Fruits like
the burdock, for ex-
ample, are provided with
hooks which catch firmly
to a passing animal, and
the fruit is carried lomr
distances before the
seeds are dropped.
Other fruits, like the
cherry, have an edible
pulp which causes the
fruit to be picked up
and carried away. A
bird may fly with the
fruit to a fence post,
and there eat the pulp
and drop the seed. In
many cases, as in the
raspberry, the whole
fruit is eaten, but the
seeds are indigestible
and are carried far from
the parent plant before
they are thrown out by
the animal.
Other fruits are fitted
for distribution by
water. In such cases
the fruit is surrounded
Figure 334. — Milkweed Plant.
Distributing seeds.
Figure 335. — Seed of Cotton.
314
TYPICAL FLOWERING PLANTS
by a light, buoyant substance, as in the bur reed and the
cocoanut, and so may be carried hundreds of miles without
injury. In the case of still other fruits, like grains, the
whole fruit is eaten, but enough are produced by the plant
so that many may be destroyed and yet some be left to
serve as seed, and thus prevent the plant from becoming
extinct. Squirrels, in storing up food for the winter often
bury nuts which are not used, and some of these are sure
to grow.
LABORATORY STUDY OF SEED DISPERSAL
Every season of the year affords material for this phase of plant study.
Record your result as follows :
Agencies
Devices
r.
a>
-d
3
"ci
"35
CO
M
3
.£ O
6
£
c3
<
o
y,
r-r!
P
n
c
-3
^
Dandelion . . .
Maple ....
Burdock . .
Cherry ....
Etc
228. The Struggle for Existence. — In the process of dis-
tribution, six or eight seeds from a plant may fall in al-
most exactly the same place. It is probable that all will
begin to grow, but only one or two will live, because there
will not be sufficient light, food, or moisture for all. In
this case the plants which get the best start or have the
most vigor crowd out the others. In biology this effort
to secure the conditions necessary for life is known as the
struggle for existence. The result of this struggle is spoken
of as the survival of the fittest.
ENEMIES OF THE BEAN
3 1 5
Figure 336. — Bean Plant
Injured by Bacteria.
229. Enemies of the Bean. — Besides this struggle to gel
its share of light, food, and moisture, the bean plant has
to contend with enemies. One
enemy is a plant or bacterium
(Chapter XXI II) which lives
upon the tissues of the bean.
This bacterium causes the dis-
ease known as bean blight, one of
the most destructive diseases of
beans, and one which scientists
have been unable to prevent or
cure. The plants having bean
blight appear wilted, and have
clear watery spots in the leaves
which, after a time, turn brown,
dry up, and drop out, leaving a hole in the leaf where
each spot was. The bacteria which cause the disease
enter through the stomata, appear first in the cotyledons,
then work into the
stem, and finally kill
the plant by stopping
up the sap tubes. The
bacteria arc carried by
insects from one plant
to another.
Any insect which
carries these bacteria
is indirectly an enemy
of the bean plant, hut
bean weevils injure it
directly ( Figure 337 >.
The female weevil
gnaws holes through the young pod and pushes her eggs
into the pod or into the young beans. The eggs develop
Figure 337. — Beans Damaged by Weevils.
316 TYPICAL FLOWERING PLANTS
into grubs or larvae, which get their food from the sub-
stances of the bean seed. If the grubs mature, the weevils
may craAvl out, thus leaving large holes in the bean. The
loss to the farmer comes not only in the food actually eaten
by the weevils, but also in spoiling the beans as food
for man.
If the pods show that the beans have been pierced by
weevils, the development of the eggs can be prevented by
storing the beans in a cold place. A test for the presence
of weevils is to place the beans in water, where those that
contain Aveevils will float.
230. Enemies of Corn. — One great enemy of corn is a
fungus (see page 360) called corn smut. This fungus
destroys the corn kernels by living on the food in them
and filling the whole kernel with black, sticky spores.
Grasshoppers injure the corn plant by eating the leaves,
and plant lice by sucking its juices.
In speaking of an animal as a friend or an enemy of a
plant or of man, we should remember that every plant and
animal is only endeavoring to maintain its own life. We
regard them as enemies when they destroy or injure some-
thing which we are trying to raise to maintain our own
lives, and as friends when they destroy our enemies.
231. The Raising of Beans. — Beans are raised in large
quantities for food. In New York, Michigan, and California
more than nine million bushels were raised in the year 1915.
Michigan raised four and a quarter million bushels, and
New York one and a quarter million bushels.
A crop of beans can be planted, cultivated, harvested,
and threshed by tools and machinery. But before beans
can be used as food they must be examined by some one
so that all those discolored or specked by weevils may be
discarded. Beans unfit for human food can be eaten by
such animals as hogs and sheep. So we find that where
HISTORY OF BEAN PLANT 'Ml
the raising of beans is an important industry, the raising
of hogs and sheep is also practiced extensively. Sheep eal
not only the rejected dry beans, but also the pods.
Certain varieties of beans are eaten when young and
« I
green, the pod itself being used as an article of food.
Figure 338. — A Field of Beans.
These "string beans" are raised extensively in some
localities and are canned for the market. In this industry
much of the work has to be done by hand.
232. The Value of Beans as Food. — Beans furnish more
protein and yield more energy than any other kind of plant
food except wheat. Compared with the cost of meal or of
eggs, vegetable forms of protein are much cheaper, and
beans are the cheapest of all. String beans do not contain so
much nourishment as dry beans. Beans properly cooked
are both digestible and palatable and should form an even
more important part of our diet than at present.
233. History of the Bean Plant. — The bean and the mem-
bers of the bean family (beans, peas, clover) are known to
have been cultivated from the earliest times .>!' human
history. They are spoken of in the Bible under the name
of pulse (Daniel i. 12), and mention is made of them in the
records of the Kgyptians, (i reeks, and Roman8. When
America was discovered, the Indians were cultivating pole
318
TYPICAL FLOWERING PLANTS
beans. Beans are now widely distributed, one or more
varieties being grown in all temperate regions.
The value to the soil of the plants of the Pulse family
has long been known, bat the reasons for it have not been
understood until recently. As we have seen, bacteria in
the roots of beans gather nitrogen which goes to replace
that drawn from the soil by other plants. Soils which
lack nitrogen may be
improved by growing
on them a crop of
the pulse family and
then plowing it under.
This method of enrich-
ing the soil is known
as " green manuring."
See page 270.
The bean family in-
cludes such well-known
plants as peas, peanuts,
clover, and alfalfa. The
peanut has the peculiar
habit of thrusting its
blossoms into the ground after they have been polli-
nated. The pods mature there and are harvested by
digging.
234. The Raising of Corn. — Most of the work of planting,
cultivating, and harvesting corn is done by machinery.
Hand work is necessary only in removing the ears from
the stalk and the husk from the ears. Because corn is so
valuable a food for men and animals and because so much
of the work necessary in raising it can be done by machin-
ery, corn raising has become one of the most important
industries on the easily cultivated level prairies of the
Middle West.
Figure 339. — Peanuts.
THE RAISING OF CORN
319
z
c
p
o
D
Q
O
a.
Qu
2
O
O
u.
o
a.
<
5
CO
D
O
320 TYPICAL FLOWERING PLANTS
235. History of the Corn Plant. — The corn plant was
found growing in America when the New World was
discovered, and it was one of the principal foods of the
Indians. Now corn is grown wherever the climate is not
too cold for it to come to maturity.
236. Economic Importance of Plants. — From a biological
point of view much of the study of plants is concerned with
the life of the plant itself, considered as an organism;
what its problems are, and what peculiarities it has devel-
oped which have aided it in the struggle for existence.
There is, however, another point of view, — the importance
of plants to man as the source of his food supply. Within
recent years, this has come to be more fully recognized
than ever before, and as a result, agriculture as an industry
has been almost revolutionized by the application of scien-
tific methods.
Man has learned to take a wild plant and, by cultivation,
selection, and cross-pollination, to improve any part of the
plant he wishes. Man is the only animal intelligent enough
to do this, and his success depends upon his following such
natural laws as he has been able to discover. Students are
constantly endeavoring to learn the conditions under
which each plant thrives best, — the kind of food, soil-
temperature, amount and kind of cultivation; what dis-
eases it is likely to have, and how to prevent and cure
them.
SUMMARY OF THE BEAN
The bean is a typical flowering plant and is represent-
ative of the dicotyledons. The bean seed contains an
embryo which is nourished by the food in the cotyledons.
A bean plant has roots to hold it firmly in place and to
gather the water which contains part of the plant's food.
It has a stem to hold the leaves to the light and air, and
SUMMARY OF CORN 321
to carry water and food. The Leaves are the pari of the
plant where most of the vital processes are carried on.
The vital processes which occur in the leaf are respiration,
photo-synthesis, or the making of food, excretion, and
assimilation.
The bean flower contains the organs necessary for re-
production. A seed is formed when the nucleus of a
pollen grain unites with the nucleus of the egg eel] in tin-
ovule. The fruit of the bean is the pod which contains
the seeds. The bean depends upon insects for cross-
pollination.
The raising of beans is an important industry. Beans
probably once grew wild, but now they are widely culti-
vated. Their chief value as food is due to the large amount
of protein in the seed.
A bean plant which has successfully completed its life
work has added to the sum total of the solid matter on
earth, and has left stored-up material which may be used
either as food for animals or for the new plant which
the seed contains. The plant has added to the supply of
oxygen in the air, and by decomposition through the aid
of bacteria leaves the soil richer in nitrogen.
SUMMARY OF THE CORN
The corn is a typical monocotyledonons plant. Food for
the embryo is stored at one side of the grain. This embryo
is supplied with food prepared in a modified cotyledon.
A corn plant has many roots, all of about the same size.
which srather for it water and inorganic matter and hold
the plant in the soil. In addition to the regular loots,
there are prop-roots. The leaves of coin have parallel
veins and clasping bases. The leaves perform most of the
vital processes of the plant. The stem has a hard rind and
322 TYPICAL FLOWERING PLANTS
scattered fibro-vascular bundles. The fruit consists of
grains in which the ovary adheres closely to the seed.
Corn depends upon the wind for pollination. The stamens
are in the tassels and the style of the pistil is the silk. It
is a monoecious plant.
QUESTIONS
How does the bean plant begin life ? Explain the work of each part of
the plant. What is the importance of photo-synthesis ? What is the dif-
ference between pollination and fertilization ? Why are beans valuable ?
What is a food ? How can you show that any given substance is a food ?
How do roots help the leaves ? How do the stems help the leaves ?
Compare the corn plant with the bean in structure, importance, etc.
REFERENCES
Campbell, University Textbook of Botany, p. 9.
Coulter, Barnes and Cowles, Vol. I, pp. 363-380.
Kellogg, The Animals and Man, Chapter 15.
Leavitt, Outlines of Botany. Roots, pp. 26-44.
MacDougal, Enzymes, pp. 173, 265, 274.
Needham, General Biology, pp. 7-33.
Sedgwick and Wilson, Biology, Chapter I.
U. S. Department of Agriculture Bulletins.
Coulter, Plant Life and Plant Uses, Chapters 1, 2, 4, 5, 6, 7, 8.
CHAPTER XX r
OTHER FLOWERING PLANTS
237. The Flowering Plants. — True flowering plants are
the most highly developed of all. They arc numerous,
it being estimated that
there are 120,000 kinds.
Some varieties are so
small as hardly to be
noticed, while others,
like the hardwood trees,
are very large. Some
live submerged in the
water, while others are
found only in deserts.
The flowering plants
are of special interest
on account of their in-
timate relation to our
daily life, and on account
of this close relationship
we should study some
of the most common
Figure 341. — Walnut Tree.
families, such as the grass, rose, mustard, and the like, all
of which are easily recognized.
The Grans Family. — The grass family has long narrow
leaves with clasping bases and parallel veins, fibrous
roots, and inconspicuous flowers which are pollinated by
the wind. The grasses arc the most important of all
323
324
OTHER FLOWERING PLANTS
(A
H
<
o
u.
o
O
H
O
Q
O
cu
It
o
<
ON
CO
U
a:
o
OTHER FLOW K RISC PLANTS
325
2
O
H
O
D
Q
O
a,
2
r
u.
o
a.
<
a
326
OTHER FLOWERING PLANTS
Figure 344. — The Cereals.
a, wheat; b, oats; c, barley; d, rye.
plants as food for man and the animals which he uses.
This family includes corn, wheat, oats, barley, rye, rice,
and similar grains. Wheat and barley are mentioned in
the earliest literature and were among
the first plants cultivated for food. As
men learned to till the soil and harvest
these grains, agriculture became estab-
lished and a marked step towards civili-
zation was made. In China and India
millions to-day depend very largely upon
rice. In 1915 the United States pro-
duced 3,054,535,000 bushels of corn,
1,011,505,000 bushels of wheat, and
28,974,000 bushels of rice.
Lily Family. — Lilies have parallel-
veined leaves. The flowers are made
Figure 345 -Lily- uP °^ a six-parted perianth (calyx and
of-the-Valley. corolla taken together), six stamens, and
THE CROWFOOT FAMILY
327
Figure 346. — X-ray of Easter Lily.
a three-parted pistil.
The fruit is a capsule.
Lilies are cultivated
chiefly for decorative
purposes.
W<dnut Family. — The
trees of this family
furnish us with nuts and
valuable lumber. The
monoecious flowers are
grouped in catkins. The
leaves are alternate and
pinnately compound.
All the walnuts and
hickories belong to this very useful family ( Figure 341 ).
Beech Family. — Like the walnut family, this uri""p
consists of trees, of which the beech, oak, and chestnut
are the most common. All are valuable for lumber and
firewood. The leaves are simple, alternate, and straight-
veined. The flowers are monoecious.
Crowfoot Family. —
This large family is valu-
able to US for tin' medi-
cines (mostly poisonous")
which it furnishes. The
medicinal members <>t
this family arc hydrast is,
aconite, hellebore, and
Larkspur ; while other
members, as clematis,
peony, and columbine,
arc cultivated for orna-
ment. The common
Figure 347. — Leaves and Bud of Beech, buttercup shows most
328
OTHER FLOWERING PLANTS
Figure 348. — Wild Columbine.
Figure 349. — Stamens and
Pistils of Rose.
of the characteristics of
the crowfoot family.
The leaves are commonly
dissected ; the petals,
sepals, and pistil are all
disconnected. The juice
of the buttercup is color-
less and is biting to the
taste.
Mustard Family. —
Garden vegetables such
as the turnip, radish,
cabbage, horse-radish,
and mustard belong to
this family. All have
regular flowers consist-
ing of four sepals, four
petals, and six stamens.
The corolla is in the
form of a Greek cross.
These plants have a
pungent, watery juice
which is non-poisonous. The
fruit is a kind of pod called a
silique.
Rose Family. — The flowers
are regular with the calyx usually
of five sepals and the corolla of
five petals. The leaves are
alternate and usually serrate on
the edge. The rose family is as
important in furnishing the
luxuries of our food as the grass
family is for the necessaries. To
THE PARSLEY FAMILY
329
this group belong all of the common orchard fruits, such as
apples, peaches, and plums, and many of the common
berries, such as the raspberry and
strawberry. Many of the members
of this family are also cultivated for
ornament.
Pulse Family. — Beans, peas,
vetch, alfalfa, peanuts, clover, and
the like are members of this family.
These plants may be recognized by
their irregular, papiliona-
ceous flowers, alternate
leaves with stipules, and
by their having the fruit
in the form of a pod.
This family furnishes us
with most of our vesre-
table protein food. The
plants improve the soil
by the aid of bacteria. Figure 350. — Rose Flower
Wisteria, red bud, and Turning into a Fruit.
the locusts are cultivated <*> early staSe ; *>, later
for ornamental purposes.
Flax Family. — While this is not a large
family, yet it furnishes all of our Linen. Flax
rarely grows wild, but requires cultivation.
Mallow Family. — This family is also impor-
tant in furnishing material for cur clothing, as
the cotton plant belongs here. Hollyhock and
Figure 351. althsea are forms cultivated for ornament.
of Rose/ Parsley Family. — This family includes such
garden vegetables as parsnip, parsley, and
carrots, and plants like fennel, dill, coriander, and caraway
used for medicine and for flavoring food. These plants
**i
^
330
OTHER FLOWERING PLANTS
THE NIGHTSHADE JAMIL)
331
have hollow, ribbed stems; alternate, compound leav< .
and flowers in an umbel. See Figure 308.
Figure 353. — Stipules
of Rose Leaf.
Figure 354. — Flower of
Mallow.
Mint Family. — The members of this family are easily
recognized by their square stems, opposite leaves with
crenate margins, and bila-
biate flowers (an irregu-
lar flower divided into
two parts). Peppermint,
spearmint, catnip, hore-
hound, pennyroyal, sage,
savory, and thyme are
some of the mints used
for medicine and in food.
Nightshade family. —
Here are found many
poisonous plants, as to-
bacco and Jimson weed
from which stramonium
(similar to belladonna
but more powerful) is
obtained. The tomato,
potato, and egg-plant
are used for food.
Petunias are cultivated Figuke 355.- Water Huklh.und.
332
OTHER FLOWERING PLANTS
2
O
o
D
O
Ou
2
O
H
O
O
u.
o
<
CO
UJ
o
6
£
H
THE NIGHTSHADE FAMILY
333
Figure 357. — Self-heal
A common weed.
5 .. A '
5* 7» \V ' - . f*
HA i
. •*
MSfn^ • x
Figure 358, — Hedge Nettle.
334
OTHER FLOWERING PLANTS
Figure 359. — Common White Daisy.
for ornament. The foliage of all these plants is rank-
scented, the leaves are alternate, and the flower five-
parted.
The Composite Family. — This family is typified by the
common daisy and dandelion. They have their flowers in
heads and are of two kinds, ray-flowers and disk-flowers.
This is one of the largest
families of plants, and
from the standpoint of
the botanist, the most
complex. It contains
our common weeds, such
as the daisy, dandelion,
golden rod, aster, bur-
dock, thistle, and hawk-
weed.
Not all the flowering
\y
1
Figure 360. — Dandelion.
THE COMPOSITE FAMILY
335
336
OTHER FLOWERING PLANTS
plants are beneficial to man, and every farmer and gardener
has to struggle with the weeds.1 Some of the members
of the composite family,
like the goldenrod and
daisy, lend a charm to
the fields, and many
people dislike to think
of them as obnoxious
plants. But they pre-
vent the grass from
growing, and cattle will
not eat them either in
the winter or in the
summer, so that they are
a nuisance to the farmer.
A weed, then, may be
defined as a plant which
interferes with the
growth of some useful
plant. Weeds are suc-
Figure 362. — Canada Thistle. cessful in growing and
in living, because they
have strong roots, produce many seeds, and have numer-
ous devices for distributing their seeds.
SUMMARY
The flowering plants are the most highly developed of
all the plants and bear an intimate relation to mankind.
The many grasses and cereals furnish, animals and man
with much of their food. The cultivation of these plants
has aided the development of civilization.
1 Thompson, "Distribution of Weeds by Means of Farm Seeds." School
Science and Mathematics, December, 1915, page 770. Georgia, A Book of
Weeds-
Ql'KSTlOXS 33'
QUESTIONS
What plants furnished part of your f<>« >< J t < »-<l;iy ? In what part of tin-
plant was this food made? In what part stored? What fruits do you
eat? Which plants jjrow these fruits? Where <l" these plants lii
Name plants, parts <>f which are used in medicine. What plants are u- 'I
in making paper? What parts of a plant are used in making hous*
What kinds of cloth are made from cotton? from linen? from .-ilk?
from wool ? What are the common weeds ?
CHAPTER XXII
THE SIMPLEST PLANTS
238. Introduction. — Many plants when full grown never
have mere than one cell and are so small that they can
be studied only through a microscope. All of these
minute plants have long scientific names, often hard to
remember, but they are the same names which the English,
German, or Japanese children have to learn when they
study these plants.
The two plants discussed in this chapter belong to the
group known as the Green Alyce (Latin, algce, seaweed).
The names of these two plants
are Pleurococcus (plu-ro-kok'iis)
and Spirogyra (spi-ro-ji'ra).
We are now to compare these
microscopic plants with the bean
plant with its many parts com-
posed of hundreds of cells, which
is able to respire, make its own
food, and grow bean seeds.
239. Pleurococcus. — Pleurococ-
cus is a widely distributed,
single- celled plant which grows in great abundance
upon the shady side of trees, old buildings, and rocks.
After a rain it is conspicuous in these places as green
patches. A bit of this green substance examined with
a microscope shows many green cells. Each plant, or
we may say, each cell is a somewhat roundish structure
338
Figure 363. — Pleurococcus.
a, single cell; b, cell dividing;
c and d, groups of cells.
SPIROGYRA 339
with a clearly defined cell wall. The contents <>f the cell
are green, due to the chlorophyll which conceals all parts «»t'
the cell except the nucleus. Tin; nucleus usually li«-^ uear
the center of the cell. As lun«r as the cell is full of chlo-
rophyll, the cytoplasm cannot be Been ( Figure 363).
Pleurococcus makes its own food as tic bean does, ami
apparently it is able to digest the starch and protein which
it makes in a manner similar to that of the bean. When-
ever a number of pleurococcus cells are examined, some
are found to be dividing. In this division the nucleus
forms two nuclei which move apart. A partition wall
forms and two cells take the place of the old or parent
cell. This method is called fission (Latin, Jixsn*\ cleft ),
and is the simplest form of reproduction. In pleurococcus
the cells do not always separate at once, but form groups
of two, three, or four cells (Figure 363).
SUMMARY
This simple unicellular (one-celled) green plant, pleu-
rococcus, lives and makes its own food and grows new
cells. While there are no flowers and seeds as in tie-
bean, yet this plant is able to reproduce itself. All of
the important life processes found in the bean take place
in the simple, single cell.
LABORATORY STUDY OF PLEUROCOCCUS
Study this as an example of a plant which consists of a Bingle cell,
but still performs all the processes common t.> higher plants. Soak :i bit
of bark and scrape it ucntly to ^et the pleurococci cells, some ot which
may be in groups. Draw a single cell ami a group of .ells.
240. Spirogyra. — This plant is best known as the "pond
scum " which l;to\vs in most fresh water ponds and in
slow running streams. It may be kepi for some time in
glass dishes in a laboratory. Instead of being made up of
340
THE SIMPLEST PLANTS
single cells or clusters of cells, the cells of spirogyra are
cylindrical in shape and are attached end to end. This
results in long, fine threads which float in the water in
large masses.
The individual cells of spirogyra are provided with one
or more narrow green bands arranged spirally within the
t" — r""1-?^ |fT;-;T)^^»J•<v^:v■■."-■■^
v^~
<hJ
Figure 364, — Spirogyra.
protoplasm. These spiral bands of chlorophyll are the
special structures which manufacture food (Figure 364).
The cells of the filament increase rapidly in size and di-
vide, and thus the filaments increase in length. As each
cell divides, the cell wall grows in at right angles to the
length of the plant. Spirogyra grows so rapidly in the
spring that in a short
time the water may be-
come polluted. The
bubbles found among a
mass of spirogyra are
the oxygen which the
cells give off during
photosynthesis.
During the summer
there are times when spirogyra reproduces in another
manner (Figures 365 and 366). Two cells of adjacent
plants join by putting forth tubes which fuse on meeting.
The contents of one cell pass through the tube, and flow
into and unite with the contents of the other cell. Thus
there is formed a single roundish mass of protoplasm
surrounded by a thick wall. This mass of protoplasm
Figure 365. — Spirogyra Conjugating.
SPIROGYRA
341
is called a sexual spore, because two cells unite to form it.
The two cells which thus unite are called gametes and are
identical in all their parts. This spore, therefore, is known
as a zygospore (Greek, zy<ios,
yoke; spora, seed). In the
formation of a zygospore, the
cells are joined permanently and
a form of sexual reproduction
is present.
As a zjrgospore, spirogyra can
live in a resting condition dur-
ing periods unfavorable to its
growth, as in winter or during a
drought. When conditions again
become favorable the zygospore
germinates and grows into a
filament. The spirogyra is able to do the same things
which a pleurococcus does and has the same life
processes.
Figure 366. - - Microphoto-
graph of Conjugating
Spirogyra.
LABORATORY STUDY OF SPIROGYRA
Notice : (1) the clear outer part called the cell wall ; (2) the mail
mass of the cell, a substance called cytoplasm. (This ran be seen easilj
by putting a strong sugar solution under the cover glass. The cytoplasD
draws away from the cell wall into a compact mass in the center of tin
cell.) (3) The darker portion of the nucleus, in <>r near the center 01
the cell. (This can be seen clearly by patting a drop of weak iodine
under the cover glass, using fresh material for this test.) (4) A spiral
band of green coloring matter, chlorophyll, containing bright spots.
Examine spirogyra in a mass, floated out in water in a ulass oron ;■
plate. Feel of it and observe that it is slimy. Note its color and delicai
After it has been in the sun for a lime, note the bubbles of gas entangled
in the spirogyra. which help to make it float With a microscope •
amine filaments which are joined in places by outgrowths from othei
filaments. Such filaments are said to be in conjugation. Draw the out
growing tubes, the emptj cell, ami the zygospore or zygote.
342 THE SIMPLEST PLANTS
SUMMARY
Both pleurococcus and spirogyra are called algae, and
each is typical of many other plants of the same kind.
Our chief interests in them are that they are adapted to
life in the water from which they obtain most of their food
and that each cell is capable of carrying on all the life
processes for itself. Plants like pleurococcus are called
unicellular ; those like spirogyra, which consist of many
cells joined end to end thus forming a strand, are called
filamentous algce. Pleurococcus is found on old buildings,
fences, posts, rocks, and on the bark of trees. It shows
more plainly in wet weather than in dry, for then it is
growing. Spirogyra grows in running water, attached to
objects on the bottom, or floats in masses on the surface
of ponds, ditches, and sluggish streams. Neither of these
plants has any economic value.
Algae are simple plants which grow in water or in moist
places. Fresh water algae are usually small. Algae illus-
trate how a plant cell carries on the life processes. The
cell is the unit of plant structure, and plant cells are
similar to animal cells in all essential respects.
QUESTIONS
What is a cell? Compare plant with animal cells. Explain the
process of conjugation. In what respects is the formation of a zygospore
similar to the process of fertilization in the bean ?
REFERENCES
Atkinson, High School Botany.
Bennett and Murray, Cryptogamic Botany.
Bergen and Caldwell, Botany.
Leavitt, Outlines of Botany.
CHAPTER XXIII
THE SMALLEST PLANTS (BAOTEEIA)
241. Bacteria. — Bacteria are the smallest of all plants
and can be seen singly only through the aid of a powerful
microscope. We do not know all about their life pro-
cesses, but we have learned much about their effect.
We constantly hear about these plants, cither under their
correct name, bacteria, or under the names of germs <>r
microbes. Two incorrect ideas concern-
ing bacteria are prevalent, — one, that
bacteria are animals, and the other, that
all of them are harmful. It is definitely
known that bacteria are plants ; that
small as they are, they are among the
most important plants in the world ; that
most of them are helpful, and only a FlG
few harmful. They are, however, so
much like the one-celled animals (protozoa) that the
word germ is not unnaturally used to cover both.
242. Shape and Size of Bacteria. — Bacteria, according to
their shape, are grouped into three classes: (1) round
(the cocci); (2) rod-shaped, like an unsharpened pencil
(the bacilli); (3) those that are shaped like a corkscrew
(the spirilla). Most of the names for the different bacteria
contain one or another of these words, thus indicating the
shape of the bacterium1 under discussion. The spirilla
and the bacilli often have on one or both ends tiny thread-
1 Bacterium, singular of bacteria.
34:;
344
THE SMALLEST PLANTS (BACTERIA)
like hairs by which they move, so that the first observers
not unnaturally thought they were animals.
An indication of the minuteness of these plants is that
fifteen hundred of the rod-shaped bacteria will hardly
reach across the head of a pin. When bacteria are grown
in the proper kind of substance, there are so many in a
cluster that they appear as tiny spots or points, often
tino-ed with a faint color. When seen alone under the
microscope, they are clear, almost transparent, and color-
less, and often have a bright, shining spot on the inside.
243. Where Bacteria are Found.
— Bacteria are everywhere, —
in the air, as invisible dust ; in
the upper layers of the soil ;
and in water. We breathe in
the microbes of the air with
every breath, but generally
with no injurious result. Every
bacterium has its own work to
_ do, and a healthy body gives
Figure 368. — Soil Bacteria, little opportunity for most
kinds of bacteria to do harm.
244. Conditions Necessary for the Growth of Bacteria. —
Like all other plants, bacteria must have all the proper
conditions before they can grow and multiply. Their
food is chiefly plant or animal matter, but they cannot
make use of food except in the presence of warmth and
moisture, and most of them require oxygen in addition.
They get the oxygen from the surrounding air.
245. Life Processes. — In the preparation of their food
bacteria break up substances or decompose them, causing
the condition known as decay. They use some of the
material resulting from decay ; some they set free in the
air ; and the remainder is left on the earth to be used by
LIFE PROCESSES 345
higher plants. In changing dea<l matter — plants. Leaves,
and animals — to a form which again becomes a part of
the earth, bacteria perform a service valuable to man.
Reproduction occurs in bacteria through simple fission.
Sometimes bacteria, break entirely apart, while in other
cases they remain connected, forming a chain. Under
favorable conditions each cell can grow t « > full size in half
an hour and be ready to divide again. It is this abilil
to multiply rapidly which makes them of so great impor-
tance, for a few hundred bacteria, even of the harmful
ones, could produce little effect.
In the process of growth, bacteria produce two sub-
stances, enzyme (see page 172) and toxin (toxin: Greek,
toxicum, poison). Enzymes produce fermentation, a break-
ing-up process of which man makes use to secure certain
flavors and odors, as well as to soften hard materials.
Toxins are usually poisonous to living organisms, includ-
ing the bacteria which produce them.
Enzymes cause the pleasant flavor of such articles of
food as cheese and butter. The quality of tobacco depends
largely upon the kinds of bacteria which have been at
work upon it. Such bacteria are classed as helpful, as are
those which gather nitrogen for the plants of the bean
family. Other helpful bacteria are those which make it
possible for man to use sponges by ridding them of t lu-
soft, slimy substance with which they are filled when
alive, as well as the bacteria which soften the useless parts
of the flax plant so that the rest of it may be separated
and made into linen.
When food, air, warmth, or moisture is not sufficient,
bacteria cease to grow and go into a resting state. That
is, they change their form, and surround themselves with
a substance which protects the soft protoplasm from being
harmed by freezing, heating, or drying. The simple
346 THE SMALLEST PLANTS (BACTERIA)
plants all do this, but the simpler the plant, the more
easily does it resist. It is this ability to withstand un-
favorable conditions and to resume growth when condi-
tions change for the better that makes bacteria such " good
friends and such bad foes."
LABORATORY STUDY OF BACTERIA
Prepare culture plates of agar-agar from the following formula :
Agar-agar Formula for 1000 c.c.
Agar-agar 1 15 grams
Beef extract 3 grams
Peptone 10 grams
Salt 5 grams
Water 1000 grams
Boil material for the agar-agar formula ; add sodium hydrate till the
color of litmus paper is not changed ; cool to about 56 C, and beat
into this one whole egg, including the shell. Warm slowly to the boiling
point and continue till the egg is firmly coagulated; then strain the clear
medium through a cheese-cloth on to moist cotton in a filter funnel.
Work rapidly. Cool, and then boil once more. Filter through cotton
into test tubes. Each tube should not be more than a quarter full. Plug
the tubes with cotton. Then sterilize this mixture in the test tubes by
placing them upright in water and boiling twenty minutes on each of
three successive days. Let part of the test tubes cool, having the
plugged end elevated half an inch. These are called slant agar tubes.
When petri2 cultures are needed, melt up a sterile agar tube and pour
into a sterile petri dish.
1. To show that bacteria are present on one's hands. Draw the fingers
of the u.nwashed hand across the surface of the agar-agar in petri dish.
Cover and set away for four days at room temperature or two days at
body temperature.
2. To show that fewer bacteria are present on freshly washed hands.
Draw the fingers of the washed hand across the surface of the agar-agar.
Cover and set away.
3. To show that bacteria lodge under the nails. Place on culture plates
scrapings from under finger nails, (1) before washing the hands, (2) after
washing the hands.
1 Secured at most drug stores. 2 Flat, round dish with cover.
BACTERIA IN RELATION TO MILK 347
4. To show that heating milk reduces the number of active bacteria.
Sprinkle drops of milk and water on agar-agar pctri dish, 1 oatu
milk, (2) pasteurized, (8) boiled. (I'sr mv tenth milk and nine tenths
sterilized water.)
5. To show that bacteria change the medium in which they grow.
Besides the number, form, size, and color of the colonies, note whether
any change takes place in the agar-agar.
6. To show that bacteria grow best in the presence of warmth and
moisture, compare those grown under such conditions with th »wn
in a dry or a cold place. Note the influence | a | of warmth. (6) of cold,
on the rapidity of growth.
7. To show that bacteria are in the air, expose the surface of the cul-
ture plate for a few seconds.
8. To show that flies distribute bacteria. Let a My walk across the
surface of the agar-agar in the petri dish.
If bacteria have an opportunity, they work od every-
thing which is capable of decay, and so we need to know
how to prevent their working upon food and other things
which we do not wish to ''spoil." Several ways in com-
mon use are : (1) cold storage, where there is not warmth
sufficient for the growth of bacteria: (2) the use of salt
and other chemicals to prevent their getting a start, as in
the curing and smoking of meat; (o) drying fruit and
meat, thus removing water, a necessary condition for
growth; and (4) heating fruit, vegetables, milk, etc., and
sealing them in cans or jars while hot, thus killing any bac-
teria the substances may contain and keeping all othi
out. Anything prepared in this way is preserved by
being made sterile or aseptic (Greek, sepein^ to make
putrid).
246. Bacteria in Relation to Milk. — (Sec also Part II.)
Milk as it comes from the healthy cow is practically I:
from bacteria of any kind. The number of bacteria present.
however, is not of so much importance as the kind. But
if a large number of bacteria are allowed to get into the
milk, some of them are sure to be harmful and may find
348
THE SMALLEST PLANTS (BACTERIA)
conditions so favorable for their growth as to make trouble
for the person using the milk.
A high grade of milk will not contain more than 500 to
1000 bacteria per cubic centimeter. Such milk has been
well cared for and comes from healthy cows. Some cities
permit milk to be sold that contains as many as 100,000
and some even more bacteria per cubic centimeter. Such
milk comes from unhealthy cows or dirty barns, or has
been kept too long, or has "changed hands " too many times.
To deliver pure milk to the
consumer costs the producer
time, care, and money, and
consumers should be willing to
pay more for milk which has
had proper care.
Ice prevents harmful bacteria
from multiplying sufficiently
to make milk dangerous, unless
the milk is kept for too long
a time. Preservatives, soda,
borax, boric acid, formaldehyde,
and the like are sometimes used to prevent the growth of
bacteria. In some cases no immediate harm seems to
come to the persons using milk thus preserved, but some
of these substances are poisonous, and pure milk, properly
cared for, does not need them. So the use of any milk
in which preservatives are found should be avoided.
A harmless bacterium gets into milk kept too long and
forms lactic acid, thus giving the milk a sour taste and
causing it to curdle. Sour milk is perfectly wholesome for
food, but the taste is disagreeable. In 1857 Pasteur dis-
covered this bacterium. He also found that milk could be
kept for several days without becoming sour, after it had
been heated sufficiently to kill this bacterium.
Figure 369. — Clean Milk.
Showing oil globules.
Louis Pasteur (1822-1895) was a celebrated French chemist
and biologist.
After filling various academic positions. Pasteur was appointed
Professor of Chemistry at the Sorbonne. in Paris, in 1867
Pasteur is especially famous for his researches in bacteria. In
1884 he discovered a method of curing or preventing hydrophobia
by inoculating with the poisonous virus in an attenuated form.
In 1874 the French government gave Pasteur a pension of
twenty thousand francs, which they increased the following year,
in consideration of his services in science and industry.
SOURCES OF DANCER IX MILK
WW)
This process, called after its discoverer pasteurization,
consists in heating milk for twenty minutes al a tempera-
ture of 60° C, or to a higher degree for a Bhortei time, and
then cooling it rapidly. This procedure kills nearly
all the bacteria in the milk and does not change the taste
or make it hard to digest. Milk is not rendered abso-
lutely sterile, but it is a much safer food, especially for
infants. At best pasteurization is only a corrective or
precautionary measure, and we should demand that milk
be kept clean and thus free
from bacteria.
Most raw milk products have
their own forms of bacteria,
but most of these forms are
helpful. The flavor of June
butter is imparted by a bac-
terium different from the one
in January butter. So with
cheese, each brand or flavor
receives its taste through the
action of a special bacterium.
At every step in the use and manufacture of milk, it is
necessary to know the conditions under which the helpful
bacteria work best, and how to keep out the harmful on
247. Sources of Danger in Milk. — The cow herself may
be unhealthy and her disease transmitted through the
milk. Of the several diseases which this animal may
give, tuberculosis is the most common. Children are
more liable than adults to take the disease in this way.
There is no necessity to be in doubt about a cow's being
infected with tuberculosis, for in 18lJ0 Koch discovered
the tuberculin test, which enables the dairyman to detect
the disease. This test is now commonly applied and in
some cities owners of herds which have been tested and
Figure 370. — Dirty Milk.
350
THE SMALLEST PLANTS (BACTERIA!
found free from disease are allowed to sell their milk as
"certified," though the meaning of this term varies. Not
only is the raw milk from tubercular cows dangerous, but
also the butter and cheese made from it.
Bacteria multiply rapidly and remain active while milk
is warm, and so it should be cooled as soon as possible
after it has been taken from the cow. Milk should not
be used when it is too old, for in that case the harmless
bacteria may all have died and
harmful ones taken their places.
Milk should not be left in a
metal container, nor open to
the air, nor placed in an ice
chamber where it can absorb
the odors of other foods.
Ice cream should be eaten
only when fresh, for poisons
(ptomaines) are formed by the
action of bacteria, especially in
ice cream which has been melted
and then refrozen. Ice cream
should be made under clean and healthful conditions, and
should never be exposed to the air of the street.
Men ivho made the Study of Bacteria Possible. — The
inventor of the microscope should be placed at the head
of the list of men who made the study of bacteria possi-
ble, for without this instrument we should not know that
such plants exist. We do not know who the actual in-
ventor was, but the microscope was little more than a
toy until it was improved by a Dutch naturalist, Leeu-
wenhoek (Lu'wen-hook) in the latter part of the seven-
teenth century. Next in the study of bacteria comes
Pasteur, who discovered and studied them in their rela-
tion to the souring of milk and in other fermentations.
Figure 371. — Beef Jelly.
Exposed in sanitary dairy.
HEALTHY BODIES AND BACTERIA
351
Finally comes Koch, who discovered a way of separating
bacteria so that each kind may be studied by Itself, a
method called getting a "pur.' culture," and who aJ
invented the tuberculin test. Most of our facts about
bacteria have been learned during the past thirty-fi
years.
248. Healthy Bodies and Bacteria. — So much has been
said about harmful bacteria that a word of caution is
needed. Two facts should
make us take a sane view of
the situation : (1) for every
harmful bacterium there are
thousands of helpful ones ; and
(2) harmful ones cannot do
their work, or even live, in a
perfectly healthy body, for such
a body is constantly preparing
a substance (antitoxin) which
neutralizes the bacterial poison
(toxin). Our chief aim, then,
should be to keep well, and a few
simple rules of hygiene will accomplish this. (1) Spend
as much time as possible exercising in the open air.
(2) Sleep as many as eight hours out of twenty-four in
a well-ventilated room or out of doors. (3) Bat only
food which agrees with you, and not too much <d that.
(4) Wear seasonable clothing. (5) Keep the skin clean
through frequent bathing. (6) Have a definite occupa-
tion, work faithfully at it, do your best, and don't worry.
Figure 372. — Beef Jelly.
Exposed in unsanitary dairy.
SUMMARY
The smallest and simplest of all the plants are the
bacteria. Most of them are helpful, ridding the earth of
waste material, giving flavor to food, gathering nitrogen
352
THE SMALLEST PLANTS (BACTERIA)
from the air for plants, and aiding in the making of linen
and sponges. Some bacteria are harmful and cause dis-
eases in plants and animals. Bacteria are spherical,
spiral, or rod-shaped. They are found everywhere, un-
less special pains have been taken to remove them. If
they have plenty of food, air, moisture, and warmth, they
multiply rapidly, and
they go into the resting
state, in which they can
remain for a long time
if any or all of the
necessary conditions of
growth are lacking.
The harmful bacteria
by their growth secrete
a poisonous substance.
When there are enough
bacteria present to make
a large quantity of toxin,
the animal or plant host
is made ill. Some bac-
teria, especially in the
resting state, can bear
freezing or boiling with-
out being killed. In order to make anything " keep," it
is necessary either to kill all the bacteria by making the
substance sterile or aseptic, or we must put into it a
preservative in which the bacteria cannot grow. We
should exercise great care to avoid the bacteria known to
produce disease.
Milk, one of the most important articles of food, is a
possible source of danger from harmful bacteria which may
get into it in various ways. Milk should be kept cold,
and should be used before it is too old. The harmless
Figure 373. — Bad and Good Bottling.
The metal cap keeps out dirt which
can get by the paper stopper.
SUMMARY 353
bacteria in milk form lactic acid and cans.- the milk to BOlir.
Tlie growth of these bacteria can be checked bv pasteuriz-
ing the milk. Ice cream, if too old, is dangerous, for the
slow-growing bacteria have had a chance t<» develop.
The men who did the most to make the study of bacteria
possible were Leeuwenhoek, who improved the microscoj
Pasteur, who discovered bacteria in milk, and Koch, who
found the way to make a pure culture and to tesl cows for
tuberculosis. Many students are devoting their lives to
finding out about the various bacteria.
K very one should know the main facts about bacteria 30
that he may not have a foolish fear of them, but may be
able to take reasonable precautions against the harmful
kinds. Since a healthy body is the best safeguard against
harmful bacteria, we should, observe the laws of hygiene in
order to keep well, and at the same time, avoid, when
possible, the bacteria which produce disease.
QUESTIONS
What are the main points of likeness between a bacterium and a bean
plant? What has the pleurococeus which the bacterium lacks? Bow
can food be protected from harmful bacteria? In what respects are
bacteria harmful to milk? In what respects helpful? Why are a :
harmful bacteria not injurious in a healthy body ? If one bacterium
divides every half hour, and all live, how many will there be at the end of
twenty-four hours ? (Solve by arithmetic or by algebra.l Why <1» B an
apple with a broken skin decay more rapidly than one in which the akin
is not broken ? Why should one not put ice into water to cool it '.'
REFERENCES
Conn, The Story of Germ Life.
Frankland, Our Secret Friends and Foes.
Prudden, The Story of the Bacteria.
Radot, The Life of Pasteur.
Woodhead, Bacteria and Their Products,
U. S. Bulletin No. 56, Hygienic Laboratory Bulletin. Milk and Its
Relation to Public Health.
CHAPTER XXIV
PUNGI
249. Fungi. — The Fungi are of importance to us be-
cause: (1) some can be used as food (the so-called mush-
rooms); (2) one of them, the yeast plant, is used in
making bread, beer, and wine ; (3) others spoil our food
when they grow on bread and cake; (4) they cause many
diseases in plants.
Fungi differ from the higher plants in two respects.
They are colorless, or nearly so, chiefly because they have
no chlorophyll. They are dependent for food on plant or
animal substances, either dead or alive, because they lack
chlorophyll and hence cannot make their own foods as the
green plants do.
Fungi which live on the substances or juices of live
plants or of animals are called parasites (Greek, para, be-
side ; sitos, food) ; and those that live on dead objects
are called saprophytes (Greek, sapros, rotten; phyton,
plant).
250. The Yeast Plant. — This plant is a unicellular fungus,
too small to be seen by the naked eye. It is oval or almost
round in shape, and is nearly colorless. It has all the
parts of a typical cell, although the nucleus cannot be seen
without a special stain. Because it lives upon dead vege-
table matter, it is a saprophyte.
The Work of the Yeast Plant. — In the making of
bread, we know that: (1) yeast secretes an enzyme which
breaks up sugar into simpler substances; (2) in this pro-
354
THE YEAST PLANT
:;:>:>
Figure 374. — Yeast.
cess alcohol is formed and carbon dioxide is sel five;
(3) the yeast lives on the proteid substances in the flour;
(4) both the gas which makes bread Light and the alcohol
are driven off by the
heat of the oven when
the bread is baked.
Use is made of the
enzymes and yeast in
the making of beer, ah ,
and porter. The pro-
cess of the manufacture
of these products is as follows: The grain, usually barley,
is soaked in water to soften it. The grain is kept warm
and moist until it sprouts, and in this condition is called
malt. It is then heated and crushed. Fermentation tal.
place when warmth and moisture are supplied, the enzyme
diastase breaking up
the starch into sugars.
The liquid or wort from
this process is boiled
with hops. The wort
is again fermented, this
time by tin- aid of yeast,
the action of which is
to break up the sugars
into carbon dioxide and
alcohol. Yeast of only
one kind is used (a pure
culture) and care is
taken to keep the tem-
perature favorable to its most rapid growth. As the yeasl
grows and breaks up t lie sugar, it forms quantities of gas
and alcohol. In bread these are temporary by-products
which are lost in the baking, but in the manufacture of
Figure 375. — Fermentation Tubes.
356 FUNGI
beer they are the product sought, and every means is
taken to retain them.
Before the action of bacteria and yeast were understood,
much trouble was experienced in getting uniform products,
owing to the presence of undesirable bacteria and yeasts.
The possibility of making pure cultures, the use of the
microscope, as well as the tests which are made in the
laboratories at every step of the manufacture, have placed
the industries of bread-making and brewing on a scientific
basis.
251. Reproduction of the Yeast Plant. — The method of
reproduction of the yeast plant is similar to that of the
bacterium, but differs from it in that instead of dividing:
exactly in two, a bud usually pushes out from the side of
the mature plant. Sometimes the second plant will form
a bud before it breaks awa}^ from the first, and so a chain
is made. Oftentimes a single plant puts forth more than
one bud (Figure 374).
LABORATORY STUDY
Prepare a Pasteur solution, a good food for yeast, as follows :
Potassium phosphate 10 parts
Calcium phosphate 1 part
Magnesium sulphate 50 parts
Ammonium tartrate 50 parts
Cane sugar 750 parts
Sufficient water to make a total of 5000 parts. (This may be used for
the culture of other molds than yeast and also for bacteria.)
Yeast. — Examine yeast cells under low power. Note their glistening
appearance and their number. Under the high power try to find all parts
of a typical cell. Label and draw. Look for budding cells and chains
of cells. Draw. Make a thick paste of water, yeast, and flour. Put an
equal amount into each of three tumblers. Place one tumbler in a cool
place. Into one of the remaining stir a teaspoonful of sugar and set both
tumblers in a warm place. Examine several times a day and write down
all the differences you observe in the three mixtures. Try to give a reason
for everything you observe.
BREAD MOLD
357
252. Bread Mold. — When examined with the naked eye,
bread mold appears like a thick mass of felt, made up
Figure 376. — Bread Mold.
of colorless, closely interwoven threads. These threads
are called hyphce (hi'fe: Greek, hyphe, web) and are of
two kinds, one lying on the surface of the bread or just
below it, and the other standing
upright above the surface. The
first are the nutritive hyphaB, and
Figure 377. - Mold
Grown from Water.
Figure 378. — Cap Fungi.
the second the reproductive. On the ends of tin- latter
are round black bodies which are full of Bpores, each of
358
FUNGI
which is capable of producing a new mold plant, if it falls
into a place where conditions are favorable for growth, —
that is, where it has
plenty of food, the right
degree of warmth, and
sufficient moisture.
Other kinds of fungi
may usually be found
on a loaf of bread after
a day or two, as spores
of many kinds of molds
are floating in the air at
all times (Figure 376).
253. Other Fungi. — A common fungus is the one that
kills flies in the fall. At that time a dead fly is often ob-
served on a window or mirror, the body surrounded by
a whitish ring. Such a fly has been killed by fungus
hyphre which have filled the body. The ring is composed
Figure 379. — Puffballs.
Figure 380. — Puffballs.
of spores thrown off from the ends of the hyphse which
have burst through thin places between the segments of
the fly's body.
OTHER FUNdl
359
Figure 381. — Bracket Fungus.
The fruiting body of the fungus.
Figure 383. — Pear Scab.
Figure 382. — Tree Killed by Bracket Figure 384. Si tion through
Fungus. the Scab.
360
FUNGI
- I •.*•; \Wd -
•
Other common fungi are potato blight, red rust of wheat,
corn smut, which produces the black mass found in an
ear of corn, and the bracket fungi, which grow in large
numbers on the trunks of trees
and whose hyphae cause the
death of the tree (Figures 381
and 382).
The fungi used for food
are nourishing, but there is a
prejudice against their use be-
cause other fungi which re-
semble them closely are poison-
ous. As a matter of fact, it is
an easy task to learn to dis-
tinguish the edible from the
poisonous fungi. While the harmless fungi are now used
as food much more than formerly, only a few varieties are
raised for trade purposes (Figures 378-380).
aX£3
Figure 385. — Spores.
Section through a leaf
injured by fungus.
LABORATORY STUDY
Wet a piece of bread, put a tumbler over it, and set it in a warm place
for three or four days. Examine without the microscope to get the
general appearance. With the microscope note (1) the clear, colorless
threads (hyphae) making up the mass ; (2) the groups of spore-bearing
bodies, black and round, on the ends of the upright stalks; (3) the spores
coming out of them.
254. Lichens. — Lichens (H'kens) are grayish green
plants which look like scales. They grow on old fences,
rocks, trees, and the like and are especially noticeable
after a rain. A lichen is made up of the hyphse of a
fungus, which inclose the cells of an alga. The algal
cells in a flat lichen are usually near the top and bottom,
and the fungus is in the middle of the plant. The alga
uses the moisture which the fungus collects and brings to
the plant, and, by the use of its chlorophyll, makes food, a
LICHENS
361
part of which is used by
the fungus. The Latter,
after it has become ac-
customed to the alga,
cannot live apart from
it, and the alga, while
it can live by itself,
appears plump and pros-
perous when it is found
surrounded by fungal
threads. The partner-
ship, therefore, seems to
be helpful to both plants.
Such a relation between
organisms is known as
symbiosis (sim-bi-6'sis:
life together ; Greek,
syn, with ; bios, life).
(Figures 386 and 387.)
Lichens are interesting chiefly as representing this
peculiar interdependence of plants. They have lit tit- or
no economic importance, although in the
Arctic Regions they furnish a supply
of food for the reindeer.
We close the study of the simplest
plants with the fungi. As in the ca
of the bacteria, men have Bpenl their
lives studying the fungi, especially
those which cause disease. Much lias
been accomplished, but a great deal
remains to be done in finding out the
cure for certain fungus diseases, espe-
cially those that attack vegetables which
tion of Lichen. W6 use for food.
Figure 386. — Lichens.
362
FUNGI
FIELD TRIP FOR THE STUDY OF LICHENS
After a rainy period, examine trees, rocks, old fences, posts, and sim-
ilar places for lichens. Note the form, color, and kinds of trees having
the greatest number of lichens ; the trees having the smallest number, and
the side of the tree having the greatest number. Make the same exam-
ination during a dry period.
SUMMARY
Fungi are plants similar in structure to the algae, but
they lack chlorophyll. On this account fungi cannot
make their own food, but always have to use that pre-
pared by another organism. As
they lack chlorophyll, fungi
cannot use carbon dioxide, and
as a result that which they
produce by respiration is cast
off into the air, as is the case
with animals and with green
plants placed in the dark.
The fungi which are most
important economically are the
yeasts used in making bread,
or beer and other fermented
liquors ; the edible mushrooms ;
those that spoil food, as bread mold, and those which
cause plant diseases, such as corn smut and wheat rust.
Fungi reproduce by means of spores. The mutually help-
ful relation in which fungi and algse live in the lichen is
called symbiosis. Animals which show the same relation
are of little economic importance in this country.
Fiqure 388. — Spores of Corn
Smut.
A farm fungus.
QUESTIONS
What is the color of fungi ? Are they ever green ? Why not ? How
does their food differ from that of green plants ? How does the yeast
plant produce changes in flour ? In malt ? How does the work of bread
REFERENCES 363
mold and yeast compare with that of tin- bean '.' What are lichens '.' Do
lichens grow equally well on all Bides of a tree '.' On all fcn i How
do they appear when wet? When dry '.' What colon do you find among
them ?
REFERENCES
Atkinson, Mushrooms.
Bennett and Murray, Cryptogamic Botany.
Cook and Berkley, Fungi.
Gibson, Our Edible Toadstools and Mushrooms.
Marshall (The Nature Library). Mushrooms.
Trouessart, Microbes, Ferments, and Mold-.
Atkinson, High School Botany.
CHAPTER XXV
MOSSES AND THEIE ALLIES
255. General Features. — The plants in this group have
more parts, stems, leaves, etc., than the fungi and algse
have ; the chlorophyll is evenly distributed, and they tend
to grow erect. The life history of the mosses is more
complex than that of the simple algae (Figure 390).
If a cushion of moss is examined, it is found to be made
up of small plants packed closely together. At certain
times of the year some
of these plants have a
stiff, wiry, brownish
stalk, surmounted by a
boxlike capsule, on top
of which may be a shaggy
cap or cover (Figures
389 and 390).
256. Habitat. — Mosses
grow in moist places, for
their rootlike rhizoids are not sufficiently developed to
gather water from the soil. They thrive best in shady
woods, on decaying logs, and on stones wet by spray.
Another reason for their need of moisture will appear in
the study of their reproduction.
257. Life History. — If a dry moss capsule is shaken,
powdery spores, much like the " smoke " from a puffball,
float off in the air. When these spores fall on moist
ground, each sends out a mass of very small, alga-like
364
Figure 389. — Types of Mosses.
LIFE HISTORY
365
threads which are called the pr<>t>>/i, ma (pro-td-ne'mA:
Greek, protos, first ; nema, thread). These threads pro-
duce buds from which
leafy moss plants grow.
The latter produce
gametes (reproductive
cells which reproduce
sexually) and so the
moss plants are called
gametophytes (gamete
plants).
These gametes are of
two kinds, eggs (large
non-motile cells) and
sperms (motile cells). The egg cells are produced in spe-
cial vase-shaped organs called archegonia (ar-ke-go'ni-a),
and the sperm cells in other organs called antheridia.
Figure 390. — Diagram.
Life history of moss.
rhiroids
Figure 391.
Antheridial Plant.
Figure 392.
Archegonial Plant.
When moss plants arc reproducing, both of the reproduc-
tive organs are found surrounded by Bterile hairs at the
366 MOSSES
top of the stems. Some mosses have both antheridia and
archegonia on the same plant, while other mosses have
only one kind on each plant. The moss plant which
bears the antheridia is usually short and has on the top
a rosette of leaves, in the center of which is the sex
organ.
Many sperms come from each of the antheridia, which
move by the use of cilia when water is present, a film of
dew being sufficient. The female moss plant has on its
upper end one or more archegonia, each of which contains
an egg cell. When the egg is ripe or ready to be ferti-
lized, sperms may swim to it if water is present. A
sperm enters the archegonium and fuses with the egg cell,
thus forming a sexual cell, known as the fertilized egg
cell.
From this fertilized egg cell a sporophyte (spore plant)
grows out of the archegonium. The sporophyte consists
of a foot, a pad by which it gets its food from the gameto-
phyte, the seta, a slender stalk, and the capsule or spore-
case. While every mature gametophyte leads an inde-
pendent existence, the sporophyte is a parasite.
Thus in its life history the moss plant has two distinct
generations, the gametophyte or sexual and the sporophyte
which reproduces asexually (Figure 390).
258. Economic Value. — Mosses have little economic
value, except in cold regions where some kinds are dug
from under the snow for food for the reindeer. They are
interesting as showing a stage of development of the
higher plants.
LABORATORY STUDY
Moss (Polytrichum). Study moss plants and note the difference in
size between the male and female plants. Make a drawing to show the
difference in size and in the arrangement of the leaves. Select a female
gametophyte which has a sporophyte. Draw and label the seta or stalk,
MARCHANTIA
367
and the capsule, the box at the top. Look for moss plant- oil trees, &l
the edges of sidewalks, and on damp soil. With tin- microscope examine
archegonia and antheridia. When antheridia from fresh material
used, the sperms can usually lit- seen escaping from tin- antheridiom.
259. Marchantia. — Marchantia is u plant belonging t<>
I Do
the moss group, which grows in vciv moist places. It has
a thin, broad body or
>
* "-.- «3gn
•
> «,
thallus (thal'ltis: Greek,
thallos, a young shoot),
which is green on the
upper surface and brown
or gray on the under
side. In the middle of
the thallus is a midrib.
On the upper surface are
diamond-shaped mark-
ings, each of which lias
an opening which leads
to an air chamber below.
On the under side are
rhizoids, which hold the
plant loosely to the soil.
The marchantias are
adapting themselves to a life on land, but they are Btill
dependent upon water. Their reproductive habits art-
like those of the mosses (Figures 391 and o\^2 ).
Figure 393. — Marchantia.
LABORATORY STUDY OF MARCHANTIA
Examine pieces of the plant and identify tin- thallus. midrib, rhizoids,
and markings. Examine the umbrella-shaped, aprighl branches which
bear the antheridia or male reproductive organs, the branches with slen-
der projections which bear the archegonis or female reprodnctivi ma
With a microscope examine a cross BOCtiOD <»f the thallus, and ol the
openings and air chambers.
368 MOSSES
SUMMARY
Mosses are much more complex than algae and fungi.
Specialization is shown in the cells which gather and con-
duct water, the beginning of the absorptive and conductive
systems of plants. There is also the beginning of a sys-
tem of getting oxygen. The life history of a moss repre-
sents the alternation of generations, a generation which
reproduces by spore (asexually), and one which repro-
duces by egg and sperm (sexually). The generation
which bears spores is the sporophyte, and that which bears
eggs and sperms, the gametophyte.
QUESTIONS
In what respects are mosses more highly developed than algse, fungi,
and lichens ? Why do mosses require so much moisture ? Give the life
history of a moss.
REFERENCES
Leavitt, Outlines of Botany.
CHAPTER XXVI
FERNS AND THEIR ALLIES
260. The Group. — The ferns are the best known mem-
bers of this group, but club-mosses and rushes (horsetail |
also belong to the fern
family. The study of
coal mines has shown us
that ferns are very old
plants and that they
were formerly much
more numerous than at
the present time. The
plants of this group
have real stems, roots,
and leaves, and most of
them are larger than the
mosses. While the ferns
are not so dependent
upon water as the mosses,
they grow best in cool,
moist woods and in rich
soil.
261. A Typical Fern. —
The fern named pteris
(Figure 394) is the best
known and most widely
distributed. The stem proper is underground and lives
on from year to year, while the part above earth renews
869
Figure 394. Pteris.
370
FERNS
itself annually. Some of these stems reach a length of
ten or fifteen feet. They branch out and give off many
fine roots. Leaves, termed
fronds, form from the upper
surface of the stem and grow
up through the soil into the air.
The stem of the pteris fern is
composed of well-defined clusters
of cells which are grouped into
tissues. These tissues are :
(1) the epidermal on the outside, which protect the
stem ; (2) the fundamental, which make up the body
of the stem and carry on most of the vital processes;
(3) the mechanical tissues, variously grouped, which by
means of their thick- walled cells give the stem firmness ;
Figure 395. — Pteris Stem.
Figure 396. — Fern Frond
Showing Sori.
Figure 397. — Sori Enlarged.
and (4) the conducting tissue, which is made up of several
different kinds of cells, all of which carry liquids (Figure
395). The conducting ti«sue extends into the leaves and
LIFE II I STORY OF THE FERN
371
Figure 398. — Forked Veins of Fern.
is the vein of the leaf. During certain seasons of the
year, lines form along the margin of the under surfa
of the leaves. These lines are made up of many minute
reproductive bodies, the
sporangia ( sj >6r-an'jl-a :
Greek, spore, seed; <m-
geion, vessel). Each
sporangium contains
numerous spores. In
some ferns the sporangia
occur in dots, the sort
(singular, sorus; Greek,
^oros, heap). See Figures
396 and 397.
' 262. Life History of
the Fern. — The fern
plant just described
forms spores in the sporangia. These spores tall to the
ground and soon begin to grow. The sprout from t la-
spore is in the form of a single thread and is a protonema.
From the fern protonema there develops a small, flat,
heart-shaped body called the proihallium (Greek, pro,
before; thallos, twig) which is indispensable to the life
of the fern. On the under surface of the ji thallium
grow small bodies, the antheridia
and archegonia. The ant heridia
produce numerous motile sperm
cells, and each archegoniura a
single ess cell. A sperm cell,
.hi finding an archegoniura,
enters, fuses with the egg cell,
and forms the fertilized egg cell. The prothallium La the
fern gametophyte. See section 257.
When an egg cell is fertilized, it begins to gr«>\\ and a
Figure 399. — Sporangia.
372
FERNS
new fern plant is soon formed. The young plant remains
attached to the prothallium and gains nourishment from
Figure 400. — a, Position of Sori ; b, Section of Sorus.
4
it. As soon as the young fern is able to get nourishment
by its own roots, it begins life as an independent plant
and the prothallium dies. There is the same alternation
of generations in the fern that occurs in the mosses, the
5pores
Prothallium
■Protonema
New Fern
Figure 401. — Life History of Fern.
prothallium being the gametophyte and the "fern'1 the
sporophyte, but the latter is the longer lived and much
the larger plant (Figure 401).
RELATED FORMS
373
FIELD TRIP T( I GREENH< >i BE OF w« K)D8 TO 8T1 DY
FERNS
Note the color of the plants, the characteristic fern leaf with it .-, >t ii><»
or central stalk, its pinnsB or leaflets, and also the method of unrolling
from the base to the tip. Note the fruiting dots (sori | on the l «:i«k of tin-
leaves. In what kind of soil are ferns found? l>" they gro^ best In the
sun or in the shade? l><> the leaves remain green during the winu
Note the underground stem and its rums. Look for bads and young
leaves. Note the forked veins.
LABORATORY STUDY
Examine the cross section of a stem and note the different kind
tissue. Draw and label: (1) epidermal tissue on the outside; 2 me-
chanical, dark brown tissue in masses near the center; '■'>) conductive
tissue, large Openings ; (4) fundamental
tissue filling the rest of the space. With a
microscope examine the epidermis on the
under side of the leaf, noting the shape of
the cells and the stomata. Pull off a bit of
the epidermis and try to distinguish the
green guard cells. Examine a sorus with
low power of the
microscope and see
how it is made up of
sporangia on stalks.
263. Related
Forms. — Clul>
mosses, horse-
tails, and selag-
inella (se-laj-in-
el/la) are plants
which belong to
the fern group. Clul> mosses bear their spores in a spike
on scales which are modified leaves. In appearance these
plants are more like mosses than ferns < Figures 102 and
403).
Horsetail, or equisetum, -rows in waste or 'lamp pla<
Figure 402.
b, Sporangium ;
c, Spores.
Figure 403. — a. Club
Moss.
374
FERNS
sporangial,..
cone"
internode •-
furrows
collar of...
teeth
node-
It is a hollow stem, with
joints, a mineral coating on
the outside of the stem, and
the branches in a circle
around each joint. The con-
ductive tissue in this plant
is arranged near the surface
of the stem (Figure 404).
Selaginella is seldom seen
in northern latitudes, ex-
cept in greenhouses (Figure
405).
264. Economic Importance.
— The fern group, like the
mosses, have little economic
importance. The spores of
the club mosses are used in
making certain kinds of fire-
works (especially those used
indoors) ; also in drug stores
to keep pills from sticking
together. The plant itself is used in Christmas decora-
tion. Horsetail, so named from its appearance, was
formerly cut, tied in bundles, and used for scouring,
and this accounts for its other name, the "scouring rush."
265. The Formation of Coal.
— Ages ago ferns were more
numerous than they are now
and many of them grew to
be as large as our present
trees. Geologists tell us
that the climate was warmer
and more moist than it is
now, and conditions especially Figure 405. — Selaginella.
Figure 404. — Horsetail.
SUMMARY 375
favored the growth of fern plants. Where these large
ferns died and fell to the ground, great masses accumulated.
As the earth's surface changed, these masses became
covered with soil or water, and under tin- influence "i'
heat and pressure they changed into coal. At tin- Bame
time natural <_ras and petroleum, or rock oil, were formed.
No coal is being formed at the present time, and when our
present supply is exhausted, we shall have t<> find other
sources of heat and power.
SUMMARY
Ferns and their allies are less dependent on water than
are the alg;e, fungi, and mosses. They are more highly
organized, as they have epidermis, stomata, mechanical
tissue, conductive tissue, stem, roots, and Leaves. Their
life history shows the alternation of generations, consisting
of spore, protonema, prothallium, and sporophyte. Club
mosses, horsetail, and selaginella are closely related forms.
Coal was formed when ferns grew to the size of trees in
regions which were then hot and moist.
QUESTIONS
What parts of the flowering plant are found in the fern '.' In an animal
what corresponds to epidermal tissue? to conductive tissue ? to funda-
mental tissue? to mechanical tissue? Compare the life history of a
moss and a fern. Why can ferns do with less water than mose Illus-
trate by diagrams or sketches the life history <>t" a fern. What plants
related to ferns ? Tell how coal beds were formed.
REFERENCES
Bergen, Foundations of Botany. Bryophytes, page 277, Pteridophj
page 286.
Campbell, A University Textbook of Botany, Bryophytes, pa
Pteridophytes, page -11.
Curtis, A Textbook of General Botany, Chapters VII and VIII.
Leavitt, Outlines of Botany. Bryophytes, page 108, Pteridophytes, |
204.
CHAPTER XXVII
THE CONIFERS (aYMNOSPERMS)
266. General Characteristics. — In passing from the ferns
to the conifers, usually known as evergreens, we go from a
Figure 406. — Conifers.
At center and left. Note their undivided trunks.
lower to a higher order of plants. With the exception of
the corn and bean, none of the plants studied up to this
376
ri.xL' v// /•;/■:
:;::
Figure 407. — Staminate Strobili of
Pine.
time bears seeds, but all reproduce by spores or by ferti-
lized eggs. Most of the evergreens are seed-bearing tn
which vary in size, but which are alike in having trunks
that taper from the base
to tip without dividing.
Such trunks are called
excurrent. The ever-
green group contains
the largest plants in the
world and those which
live to the greatest age.
Their foliage is usually
composed of dark green,
needle-like leaves which
remain attached to the
tree for two or three years. Thus the trees always have
some foliage and so are termed "evergreen."
267. Pine Tree. — The pine illustrates the plants of this
family. The pine has all the parts of a dowering plant
— stem (trunk), branches, roots, leaves, seed-producing
organs, and fruit (cones).
Stem. — The trunk does not
divide, — a marked character-
istic of evergreens. In a forest
where trees arc crowded together
and there is in consequence a
struggle t<> get Light, 'he trunks
grow tall ami m08t of the
branches are near the top.
A cross section of a stem shows a scries of rings, known
as annual rings, by which the approximate age of the t:
can be told. In the spring when all the conditions arc at
their best and growth is rapid, the cells «»!' the tree art-
large and thin-walled, strength being sacrificed to size.
Figure 408. — Young Cone
of Pine.
378
CONIFERS
Figure 409. — Ripe Cone of
Pine.
But in the fall or during a dry
time in summer, the cells formed
are much smaller and the walls
thicker. These small cells which
show most plainly make up the
annual ring. During a season
in which long, dry periods occur,
more than one ring may be made.
From the center to the bark ex-
tend lines which are made of
pith and are known as medul-
lary rays. The part of the
stem where increase in thick-
ness takes place is just under
the bark.
Branches. — The branches leave the stem almost hori-
zontally and nearly in a circle around the trunk of the
tree. In the pine they
curve upward, but each
kind of evergreen has
its own habit of curva-
ture in its branches.
Leaves. — The leaves,
called needles, are long,
slender, and flattened on
one side. They grow
in bundles of two, three,
four, or five needles,
according to the kind
of pine. The leaves,
which are borne but
once in a place, remain
on the tree from two to five years and then fall off,
leaving the branches bare except near the ends.
Figure 410. — Other Cones.
a, arbor vitae ; b, hemlock.
PISE TREE
379
Moots. — The roots of the pine vary according to the
kind of pine and according to the soil, but they are alwa
extensive.
Seed-producing Organs. — Early in the spring, two
kinds of cones are found on the oew shoots which grow
from the terminal buds.
One kind looks like
short catkins, and these
cones are borne in clus-
ters near the base of the
shoot. They consist of
scales arranged spirally
around the central axis.
Each scale bears two
pollen sacs. These are
the staminate cones
(Latin sta, stand) or
strobili. They wither
soon after shedding their
pollen, although they
may remain on the tree
for a year. The other
kind of cone is short and
thick, and is found at
the tip of the shoot or
on the Side of the shoot The splendid trunk in the
., .. r™ • • .1 is that of a cucumber tree. (Hugh
near the tip. 1 his is the p Baker \
carpellate cone (female
strobilus), which is made up of scales arranged spirally
around a central axis. Bach scale near its base bears two
ovules. When the pollen is ripe, each grain, being pro-
vided with winjrlike air sacs, is easily blown about by the
wind. Some of the pollen sifts into the carpellate cone
through the spaces between the scales, which at this time
Figure 411.-- A Virgin Forest of Mixed
Hard Woods and Conifers in North-
ern Pennsylvania.
Figure 412. — Lumbering in New York.
Figure 413. — Fire Slash.
The scene of a great destructive fire in 1908.
HABITAT
381
are separated slightly.
Then the scales close
together, the cones turn
downward, and con-
tinue to grow for sev-
eral months (Figures
407-410).
Fruit. — During the
next year, the pollen
grains which are shut
up inside the scales
Figure 414.
Waste Land in Pennsyl-
vania.
The year previous to the taking of this
grow into pollen tubes photograph this land was covered with a
t c ,.-,. ,, virgin forest as shown in Figure 411.
and fertilize the egg Logging has been followed by fire, which
destroyed the humus and much of the
surface soil, making the tract a barren
waste upon which it will be impossible
to grow another such forest for many
years. Pennsylvania alone has several
millions of acres of such waste land
covered formerly by splendid virgin forest.
cells which develop in
the ovules. From the
fertilized e^ors the em-
bryo pines develop.
When the cones are
about two years old the
scales open, and allow the seeds to drop out. Bach seed
is provided with a wing by which it is blown about, for
the pine depends <>n the
wind to Bcatter its seeds
as well as its pollen.
Because 1 1 ds li<" on
the scale without being
Inclosed in an <»\ av\ . all
these plants are called
gymno9p< rm% < ( rreek,
gymnoS) naked : >/" mt<u
-■••■(I >.
268. Habitat — The
Figure 415. — Waste Land.
After the fire had passed over the region evergreens ?row m
shown in Figure 413. - 1 1 1 < 1 \ soil in temperate
382
CONIFERS
Figure 416. — Fire Train in the Adirondacks.
Figure 417. — Nursery Where Young Trees are Started.
RELATED FORMS OF CONIFERS
383
or in cold climates, but ;i lew <>f them occur where it
is very warm. The finest evergreen forests in the world
are found in the western part of North America, on the
slopes facing the Pacific Ocean.
269. Related Forms of Conifers. — • Hemlocks, spra . firs,
and balsams have smaller, flatter needles than the pines
and they are not arranged in bundles. Cedars have scale-
like leaves. Larch and cypress trees shed their Leaves in
the fall, but in other respects are much like the pin
FIELD STUDY OF GYMNOSPERMS
Most of the work in connection with gymnosperma Bhould \«- d
out of doors. The student Bhould learn to know by Bight all tin- local
native evergreens and those commonly planted for ornament. He Bhould
note the method of branching and the character of the trunk compared
with other trees. He should observe the position <»f the cones on tin-
branches and be able to give the reasons therefor. In the spring he
should look for the male and female cones or strobili, and for leaf buds in
the winter. He should examine the leaf sears and the external ru
which mark a year's growth, and decide how many years each tree k< •
its leaves. He should note the arrangement of the haves on the brand]
the annual rings in the wood and their relation to the grain of the wood,
the resin on wounds, the curvature of the branches, and the other :
tures readily observed.
STUDENT REPORT
N t: l I > I B8
MM.I B
A i.i i:i:\ \ i i: •
Nbedlbs
Needles is
. i -
-. \i ■ i no.
in m « i bs
i. \
3 m
Hemlock
White Pine
Larch
Cedar .
Spruce .
Etc. . . .
384
CONIFERS
LABORATORY
In the laboratory examine a cross section of the stem to see the dif-
ference in the cells grown in the early and in the late part of a season.
Note the pith and medullary rays. If specimens are available, examine
sections of wood from different trees. Make a collection of the woods
found in the vicinity. Examine scales from staminate and carpellate
cones. With the microscope examine pollen of pine. Draw and describe
all the rays.
270. Economic Importance. — The value of the gym-
nosperms can scarcely be overestimated. Most of the
Figure 418. — Planting Young Trees in the Adirondacks.
trees are sawed into lumber for building purposes, but
some of them are used in their natural form for telegraph
poles, masts of ships, and timbers of mines. Wood pulp,
from which most of our paper is made, is produced from
small spruce trees. The by-products of this group of
trees are of great value. From the pine come tar, pitch,
turpentine, and resin, while the bark of the hemlock was
formerly extensively used in tanning leather.
IMl'oUTANCE OF FORESTS
385
The forests of the United States cover about 550,000,000
acres, or more than one fifth of the total area.
"Generally speaking, countries having over twenty per
cent of wood lands have fores! resources sufficient to
supply their lumber industries and their firewood con-
sumption, provided that such area is properly stocked
and conserved." — Schenck, "Fores! Policy," page 71.
Yellow pine, which supplies one third of the Lumber
consumed in the United States, ranks first in value ; white
Jk.jL.
»»•»?■.«-— ^ j M^ mt + ta^*-. .
4
Figure 419. — Young Plantation in the Adirondacks.
pine, which formerly supplied the greatest amount, ranks
second; and Douglas fir, third.
271. Related Topics. — Hardwood forests are compos
of trees which have broad leaves and flowers with typical
stamens and pistils. Such trees grow either alone or in
tracts containing many evergreens, Maple trees supply
sugar and syrup, the industry being important in Ohio
and Vermont. Other hardwood trees yield fuel, Lumber,
and nuts.
272. Importance of Forests. — Forests are of the test
importance in preventing floods caused by the rapid melt-
ing of ice and snow. The snow melts more Blowly in the
386
CONIFERS
woods, not only during a midwinter thaw, but also in the
spring, and the soft, porous character of soil causes it to
absorb much water. This results in springs and rivers
being fed uniformly during the summer. Floods and
freshets can often be traced largely to denuded hills along
the streams, because hills without forests have soil poorly
Figure 420. — Young Plantation 16 Years after Planting.
fitted to prevent the water from running down faster
than it can be carried away. Floods and freshets each
year do millions of dollars' worth of damage in the de-
struction of bridges, buildings, and other property.
Another loss occurs in the washing away of the most
valuable form of soil from the hills, when the water flows
off rapidly. Not only is the soil that is left useless for
IMPORTANCE OF FORESTS
387
Figure 421 . — Pollen
of Pine.
agriculture for many years, l>ut that carried into the
streams clogs harbors and channels, making it accessary
to spend large sums in dredging.
Forests arc destroyed not only by lumbering operations,
but also by fires, many of which are caused by carelessm
Forest fires, in addition t<> destroying
the trees, render large territories useless
for agriculture by burning up the
humus, or organic part of the soil. So
great is the destruction and waste
caused by forest tires, that the national
and state governments have taken measures to prevent
them. Forests are now patrolled daily during parts of
the }Tear and apparatus for fighting fires is always in
readiness.
In addition, the government is setting out thousands of
young trees and protecting them in an effort to re-fon
bare territory, especially around the headwaters of rivers.
Where forests still exist, the government is buying them
in order that they may not be destroyed. Such tracts
are called forest reserves.
In European countries the study of forestry lias been
carried on for a long time. Their forests are made ,i
source of revenue, but all the 1 1
are never cut in a single season,
and planting keeps pace with cut-
ting. Scientific forestry is now
practiced on aboul i"1',' of the
public forests of the I Ihited States
and on about 2% of the woodlands privately owned.
Only about one fifth of the wooded area of the United
States is under government control. New York Si.it.- is
taking steps to preserve her forests and also to re-forest
large tracts which have been out over (Figures IIs 120 >•
■ " "H.
..-'.
N n
y
\
V^
e£ '..'.
\
Figure 422. — Seed of Pine.
388 CONIFERS
SUMMARY
The conifers belong to a class of the higher plants.
They have periods of active and less active growth, both
together resulting in the appearance of annual rings.
Because their seeds are not entirely inclosed in an ovary,
but lie uncovered on a scale, they are called gymno-
sperms. Conifers are of great economic importance, for
they supply much of our lumber, tar, pitch, and all our
turpentine and resin. Hardwood trees grow with the
evergreens. They belong to many families of flowering
plants and furnish lumber, fuel, and nuts. Forests help
to regulate the flow of streams and they prevent the
washing away of the soil.
QUESTIONS
How are gymnosperms like other plants ? How do they differ from
other plants ? What kind of a trunk is characteristic of gymnosperms ?
How does a tree which grows in a forest differ from one which grows
in an open field ? Why ? What are annual rings ? How are they
formed ? Describe the branches ; the leaves ; the roots ; the cones or
strobili ; the fruit. What is a sporophyte ? Name the gymnosperms.
Make a list of the uses to which lumber is put. What other products
come from the evergreen forests ? In what ways are forests beneficial ?
What are the governments doing to protect them ? What regions in
your own state are covered with forests ?
REFERENCES
Government pamphlets and bulletins.
Hough, American Woods.
Keeler, Handbook of Trees.
National Geographic Magazine.
Sargent, Trees of North America.
Schenck, Forest Policy.
CIIAI'TKR XXVIII
PECULIARITIES OF PLANT LIFE
273. Unusual Plants. — hi order to live, all plants must.
have conditions favorable to their vital processes, and
many of them develop special modifications which aid the
plant in the struggle for existence. Sonic of the modi-
fications already studied in this book arc the arrangement
of leaves or the length
of petioles to secure air
and light ; the presence
of color, odor, and nec-
tar, devices to attract
insects and thus secure
the pollination of
flowers ; and the use
of wings, pappus, and
hooks to secure the
distribution of seeds.
Many of the carnivorous
and parasitic plants are
remarkable for the modifications which make it possible
for them to obtain nitrogen, an clement lacking in the
food supply of their particular environment.
Tfie Pitcher Plant. — The leaves of this plant form a
sort of vase which retains water in the bottom. When
insects crawl into the leaf, their escape Is prevented by
hairs which grow around the opening on the inside and
point downward, and the unfortunate victim, exhausted
389
Figure 423.
Photograph of Pitcher
Plant.
390
PLANT PECULIARITIES
by his struggles to get
out, falls into the water
and is drowned. When
the bodies decay, the
plants secure the nitro-
gen which they are un-
able to get through their
roots.
The Sundew. — This
plant has round leaves
covered with long glandu-
lar hairs which secrete a sticky substance. When an
insect alights on a leaf, the hairs bend over and hold the
victim until it dies, the secretions of the plant meanwhile
digesting the soft parts of the insect. When the leaf has
Figure 424. — Leaves of Pitcher
Plant.
Figure 425. — Photograph of Sundew.
UNUSUAL PLANTS
391
absorbed this digested food, the hairs release the remain-
ing parts, which then fall off, and the hairs resume their
usual position.
Venus* Fly-trap. — - This plant has another waj to
catch insects. The leaves end in a traplike device in
two parts which lie flat like the Leaves of a 1 k. When
an insect alights on one
side, the other clo
quickly and confines the
Figure 426. — Diagram of Sundew. Figure 427. -Venus's Fly-trap.
fly by bail's on the edge which interlock. Digestion and
absorption soon take place, after which the Leaves lie flat
again, ready for another insect visitor.
Indian Pipe. — Although it produces flowers and seeds,
this plant has no chlorophyll and BO is a waxy white in
appearance. It gets its nourishment from decayed organic
392
PLANT PECULIARITIES
matter, usually wood,
just below the soil. A
fungus which grows on
the roots helps them to
absorb this prepared
food.
Mistletoe. — We are
most familiar with this
plant as a part of our
Christmas decorations.
Mistletoe has chlorophyll
and so is able to manu-
facture its own food, but
it has no roots for ab-
sorbing water, making it
dependent on a larger
plant for this necessary
part of its vital condi-
tions. The plant possesses absorbing organs which pierce
the bark of the trees upon which it grows. As a result it
does much injury to the trees by using the water which
they need for their own life processes. In the South,
for instance, the mistle-
toe is regarded as a
great pest.
274. Movements of
Plants. — Most plants
move slowly and only
in response to one of
several stimuli. Touch,
or contact, is the stimu-
lus in the case of sun-
dew and Venus's fly-
trap, both of which are Figure 429. — White Waterlily.
Figure 428. — Photograph of Birch
Roots.
Growing over the surface of a boulder.
PLAXT SOCIETIES
393
peculiar in moving quickly. Tendrils curve undei the
influence of the same stimulus, but they move slowly.
Light and darkness arc universal stimuli. Flowering
plants move toward the Light, it" it docs nol surround them
evenly on all sides. Window-growing plants Bhow this.
Plants like potatoes, which sprout in a cellar, grow many
Figure 430. — Waterlilies — Hydrophytes.
feet to get into the light. Darkness causes plants like
clover and oxalis to close their Leaves.
Moisture is a stimulus which affects the roots of a plant,
as is shown in Figure 428.
275. Plant Societies. — The term plant society is applied
to any collection of plants which grow under similar con-
ditions. The trees of the forests, and thegrass and weeds
of our lawns, are typical example-. In mosl cases water,
or the lack of it, is the basis \'^r classifying or grouping
plants in societ ies. Plants, Like some alga*. Live submerged
in the water, while others. Like the waterlilies. Live
394
PLANT PECULIARITIES
partly in the water, lifting their leaves and flowers into
the air.
Plants which live in the water are called hydrophytes
(hy'dro-fltes : Greek, hydor, water; phyton, plant). If
such plants have roots, they are little more than holdfasts,
for the hydrophytes do not need organs of absorption.
Most of the members of this plant society are without
Figure 431. — Cat-tails and Arrow-leaf.
mechanical tissue, for the water holds them firmly on all
sides. The alg?e lack a conducting system as well, for
their source of food is all about them. Waterlilies get
their oxygen and much of their carbon dioxide from the
air through their leaves, which float on the surface of the
water with the stomata on top. Air passages in the long,
slender steins convey air to the roots which lie in the mud.
Hydrophytes which lie under water have their leaves
finely divided to offer as much surface as possible to the
water and thus secure a full supply of oxygen.
PLANT SOCIETIES
395
Figure 432. — Giant Cactus.
Figure 433.- Sage Brush.
396
PLANT PECULIARITIES
Figure 434. — Diagram.
Section of the epidermis of agave, "a
xerophytic plant. Compare this sec-
tion with the section of the bean leaf
in Figure 265.
Plants which live in
desert regions, of neces-
sity, have to live on little
water. They are called
xerophytes (zeVo-fites :.
Greek, xeros, dry ; phyton,.
plant). Xerophytes usu~
ally have long roots so-
that when moisture is-
present they may gather
it rapidly. Many forms
have little surface ex-
posed to the air ; the branches are few, and there are no
leaves. The stem, which is green in color, perforins the^
work of photosynthesis. To conserve their water supply
further, the xerophytes have a thick epidermis and few
stomata. These plants
are an admirable illustra-
tion of making the most
of what one has.
Desert plants live in
regions where it is usu-
ally both hot and dry,
but plants of the Arctic
Regions have many of
the same modifications,
only in a lesser degree.
Much of the time severe
cold prevents the roots
from absorbing water,
and the plant must keep
what it already possesses.
Some of the Arctic plants, Figure 435. — Bull Thistle.
therefore, have leaves A mesophyte weed.
PLANT SOCIETIES
397
which roll to reduce the
surface and have, in ad-
dition, a coating of hairs,
both devices for retard-
ing transpiration.
Most of the plants
which we see and which
live where there are no
great extremes of heat
or cold and where it is
neither wet nor dry are
called mesophytes (mez'o-
fites : Greek, mesos,
middle ; phi/ton, plant).
They have few charac-
teristics in common, but
all have roots suited to
the soil in which they grow, and leaves which in shape
and arrangement serve the purposes of cadi plant better
Figure 436. — Lady Slipper.
I'fc) Mi
> si
Ml B S
r«?
•**?!
^B^^B w^. ^ffC
[j| \^ V
Br ^^^fl|
p>^
^mZ^i
LM.i^mk
y+- jf
Figure 437. — Long-spurri
398
PLANT PECULIARITIES
than any others would do. Examples of this are the nar
row, upright leaves of the grass, which grows thickly
~& 1/
- -.
. -
Figure 438. — Mistletoe.
A semi-parasite. This tree has no leaves.
crowded together, the broad leaves of the trees, and the
leaves of the ivy, which grows on walls, arranged like a
mosaic. Many divisions of the mesophytes might be
PLANT SOCIETIES
made, for some prefer sunn \ local imis, <>t hers shadv plaot
and so on.
Plants which live in tin
called epiphytes (ep'l-fites :
plant) because they usu-
ally attach themselves
to the stem of a larger
plant. Their modifica-
tions consist of one kind
of roots for fixing them
to their support and
another capable of ab-
air make up another group,
( ircck. epii upon : phyton^ a
sorbing and
storing
water. The latter or-
gans are called velamens
and are composed of
spongy tissue. They
are situated on the out-
side of the plant, soak
up rain and dew and
conduct it to an inner
region where it is used
as the plant needs it.
Velamens can also ab-
sorb moisture from the
Figure 439. — Diagra-
Sectional view of a branch infected
with mistletoe, showing the relation be-
tween the parasite and host ; a. branch
of host tree ; b. mistletoe ; c. primary
sinker; d, sinker from cortical root;
e, /, cortex of soft bark ; g, cambium
or growth ring; /;. wood of branch.
The starving and dwarfing of the branch
beyond the mistletoe is shown at ;'.
air. The epiphytes are
characteristic of the tropics, where the air IS full of
moisture and where rains fall frequently. In OUT
own part of the world, lichens lia\ imewhal tin-
same habit, and orchids in greenhouses are another
example.
The study of plants which deals with their distribution
and the factors which govern it is called plant <
(e-kol'o-jy : (J reck, oikos, home; hgo$, talk).
400 PLANT PECULIARITIES
276. Plant Succession. — When a swamp is drained, a
forest cleared, or a desert irrigated, plant conditions are
changed. Thus it becomes impossible for some plants to
thrive in their former habitat, and possible for others to
grow where before they could not. The replacing of one
plant society by another is termed plant succession. When
a forest is cleared and the tract burned over, the plant
called fireweed appears in large numbers, even if a culti-
vated crop is planted. After a year or two the fireweed
gives way to a growth of blackberry and raspberry bushes,
which are later replaced by grasses and weeds of various
kinds.
Another example of plant succession is seen in regions
covered by fresh lava from a volcano. At first nothing
grows. Probably bacteria and fungi appear before other
plants are noticed, but lichens are usually the first to be
observed. These die and decompose, and their remains,
together with bits of lava loosened by frost, wind, or
water, accumulate in depressions and form a soil in which
mosses can grow. The remains of the mosses add to the
organic matter in the slowly increasing soil, and, in the
course of time, ferns and larger plants can grow. The
last finally replace the mosses as they replaced the lichens.
277. Summary of Our Interest in Plants. — Our first
interest in plants is economic, that is, we think of them
first in terms of their usefulness or harmfulness to us.
As every animal in the world is dependent directly or
indirectly upon plants for food, it becomes obvious to what
a degree we are benefited by the ability of plants to make
food out of the air and the soil.
Man could live comfortably on what three plant families
furnish, — the grasses, which include all the cereal foods
and sugar; the pulse family, which furnishes most of our
vegetable nitrogen ; and the rose family, which includes the
SUMMARY OF OUR INTEREST IN PLANTS 401
plants which furnish us our luxuries in the wav of fruits.
In eating animal products, man is still dependent apon tin-
grass family to furnish food for the cattle from which be
obtains meat, milk, cheese, and butter. For clothes, man
depends indirectly upon plants for the Leather and woo]
of the domestic animals, and directly for cotton and linen.
F\'^l
. 40*1
W*
f ;£#" v«*tfd
%x*,
5 ■ "^*
1
i
■: '$$'$>' JIB
»tfV Mi
«
•
;
■
*" ^^2St^t *
Iflttr' -
Figure 440. — Tropical Vegetation.
Note how different the plants are from ours.
Plants are the source of many of the materials out of
which houses are made and furnished.
Some plants (bacteria) cause disease, while still others
provide remedies with which to cure diseases. Plants
please our eyes as we travel about. They keep up tin'
supply of oxygen in the air ; they rid the air of tin1 carbon
dioxide which we have cast off; they provide employment
for millions of men who raise food plants, manufacture
them into food, and distribute them throughout the world ;
402 PLANT PECULIARITIES
and they employ other millions in the production of cotton
plants and cotton cloth for our clothing.
The farmer who raises plants has an interest in knowing
what kind of soil and climate, how much water, air, and
light each kind of plant needs to yield him the best results.
To this end he has to know something about the habits of
plants in general, and about their enemies and their dis-
eases. He has learned by experience that some plants
grow better when planted in hills ; others in drills, and
still others sown broadcast. He is still trying to find the
best kind of plant food for each plant, and the method of
cultivation which best enables plants to get their full
supply of food and moisture, and he is still fighting weeds
which deprive the useful plants of their share of food,
water, and light. Yet he is conscious, if he stops to con-
sider, that he cannot make a plant grow. His part is to
create good vital conditions.
We are interested in the work of men who are trying
by cross-pollination, grafting, and selection to reduce the
undesirable parts of plants and to increase their capacity
for food, storage or whatever we find desirable. Luther
Burbank has made many experiments along these lines,
especially in increasing the number of fruits on trees and
in reducing the size of the seeds in berries.
278. Scientific Interest. — In addition to practical in-
terests, that is, besides the supreme importance of plants
to man and his dependence upon them, there is another
interest, — that of the scientist in plants as organisms.
The scientist studies how plants are like animals ; how
they differ from them ; how each is dependent upon the
other for waste products ; how plants depend upon animals
for the pollination of their flowers and the scattering of
their seeds, and how the plants make use of the wind and
water for the same purposes.
SCIENTIFIC IX TERES T
403
He studies, too, the increasing complexity of plants
from the simple, one-celled plants dependent upon water
for existence up through the plants which are becom-
ing accustomed to living ou land, and finally to the
which have complex: systems and complex Sowers. He
finds that all are related, and the more be Learns about
them, the more interesting does he find their relationshi]
He is interested in seeing how the changfe from water to
land calls forth changes
in structure to fit the
new environment ; how
in land plants, each one
has adapted itself in
form, size, arrangement
of leaves, and so on, to
make the best possible
use of the air and water
which it is able to pro-
cure.
In trying to find the
causes of such varia-
tions of plants the
scientist performs many
experiments, often upon
the smallest plant, for size and complexity arc no Indication
of the interest which may center in a plant structure. Bac-
teria, for instance, which are the simplest and smallest of all
plants, are being st udied more to-day than any of the others.
Every year adds to our knowledge of the nature of
plants, their relations to each other and to man. Besides
these relations due to their surroundings, plants bear I
wards each other the relation of dependence and inde-
pendence, which we have discussed under parasitism and
symbiosis.
Figure 441. — Calla.
From an X-ray photograph. One of
the new ways of studying plants.
404 PLANT PECULIARITIES
Plant life itself remains a mystery. The poet Tenny-
son has given expression to the thoughts of those who
have tried in vain to solve the many problems which have
arisen in connection with the study of plant life.
" Flower in the crannied wall,
I pluck you out of your crannies.
I hold you here in iny hand,
Little flower, root and all.
But if I could understand
What you are, little flower,
Root and all, and all in all,
I should know what God and man is."
LABORATORY
To show the response of stems1 to" gravity, place seedlings or young
plants in unnatural positions and note their effort to right themselves.
To show the response to light, examine a potato from a dark cellar, which
has sprouted in the spring ; a plant that has been allowed to grow towards
the light in a window ; the bending of seedlings, and the like. For the
storage of food, examine all the common garden vegetables and test them
for the food which they contain. If possible, find some vegetables which
have been kept for two seasons and have produced seed, and note their
appearance after all the food has been used.
Sprout slips of balsam, geranium, and ivy to get adventitious roots.
Show such roots on the stem of a tomato plant where it has been allowed
to lie on the ground.
Examine leaves in the laboratory and in the fields to find illustrations
of all the terms used. Examine onions and cabbages for example of
leaves modified for storage, and the onion also as an example of a re-
duced stem. Find examples of all the terms used in the discussion of
flowers and buds.
AIM'KXDIX A
BIRD STUDY
Oxe of the most fascinat in-- phases of Biology is the Btudy
of birds. This is easiest and mosl interesting during the
migrations, when the trees arc leafless. The early morning
is the best time of day for observing birds.
The following tables have been compiled to help pupils
acquire a more intimate knowledge of birds, — their appear-
ance, habitat, food, manner of flight, and bo on. N«»t only is
this information valuable in itself, but there are i'rw tlm
that may be learned in such a pleasant way.
■Plait A-
Brpour roo locrmriCATiON or Ribki
s
I
i- S
8
is
5>
3
Is-
3
I
1
Or/ate
tree
larvae
: Ttaltl
MX ■
orange
Ua \
I VtOB
t)IJOK
\'J"f
r'
strong
Purple nncti
tree
fkfca
I ■■ :■ : .
ti adab
! : i. 0
tmm
forked
Suift
flying
insects
dusKy
dusky
dusky
dusky
dta • .
.' :•
Solden Crooned
kinglet
tree .
. /
block
.. ,/f
fuscous fuscous qreenah forked
Bluebird
tree
r, '
;.v
blue
blue
? ..-
; I >, -i >■ :
■- -»,
//.. r'r
ground
lorper
■:■.■
scarlet
tmuml
: ■ "i
/•'/>///
ground
■. me
b*x h
rufous
■ykitr.
■ ."'
?'
trees
shrubs
nook '■■
smaller
•
90
b*xM
. -
: Eft
r -xy.t
trees
scarlet scarlet black scortet sooner
'•;>■>;
* Ural b«* lum rtc JVK«i«a g/*a •» mm* ttm r—mr
105
406
APPENDIX A
Plate S-
Dcuny Uoodpcckr
t3
5uct
— Report for feeding station —
1
%>
§
£
■*3
O
CO
/to
Light Above
m bock doon
t=
-C; O
Manner of —
comina to food—
i
13
-c:
§>
in
Yes
1
Tu)0
"5"
I
5
Yes
/fairy rloodpccher
Suet
+
/to
Crumbs
Suet
/to
Alignt Above
uaiH doun
Dead foremost
Nuthatch
Yes
Yes
Chickadee
/to
Fly directly
to food
Three
Brwn Creeper
Suet
Alignt belocj
ana ualh up
/to
One
Song sparrou
Seeds
Crumbs
Seeds
Crumbs
Suet
Alight /tear
ana hop nit
Four
No
House or
English Sparrou)
Yes
One
Yes
~Robm
Crumbs
/to
tnree
Yes
AIM Near
UQIKtoif
Grachle
Yes
Tuo
/to
Plate C-
— Report f
or Birds in
Nesting Season —
3?
"5
1
V)
4
Fj$o
Adults
Young
n
%
I
c
1
V)
\
1
N
1
1
1
?
-•J
1
Robin
bedpe
grass and
mud —
interlaced
X
X
X
Chipping Sparrou
bush
rootlets
grass, hair
1 1
X
X
X
Oriole
dm
fret
plant fibre,
grass, string
uoven
X
X
Grackle
Voruoj
Spruce
grass and
uool —
inter/acea
5
grzen
oroun
gray
li'lonp
X
Neadou Lark
jrouna
grass -
19
5
Oroun
unite
rr r»
X
Phoebe
under
eaves
flair, mud
feathers
plastered,
interlaced
4
uhite
F "
X
Cat Bird
oush
rootlets,
grass —
interlaced
5
blue
V"
X
Mourning Dove
Horuaj
Spruce
grass
X
X
X
House Sparrow
behind
eave
hay. grass,
feathers ,
heaped
X
X
BIRD STl'DY
40:
P/ate D-
— Pepori
on a
single ^a-r of Birds feedm. jng-
to
1
I
\
Aumber of rimes eocfi
/test ling is fed —
Direction from uhich
Adurts approach nest
1
1
1
I
V
1
1
5
315
AM
X
uorm
X
X
X
laun
X
3 20
i *
X
tt
-
X
X
X
X
a
9 21
ii
x
it
X
X
X
a
9 28
ii
X
it
X
X
X
—
X
X
9 30
ii
x
cherry
X
X
X
X
9 40
-
X
oorm
X
X
X
X
3 45
••
X
•■
X
X
X
lovn
9 47
ii
X
-
X
X
X
n
X
953
"
X
••
X
X
X
X
a
Plate E-
— Peport for Seasonal Activities of Birds —
1
1
CS..
.So
s
c
o
I
u
Color of young
Color of /duff
J
C3
8
O
c
5
&
Aj
-*
^
Robin
Bluebird
Chipping 5cmxj
Gold finch
Cedar Bird
Bobolink
Song Sparrou
Sandpiper
Houx Spanvu
APPENDIX B
REGULATIONS OF THE SANITARY CODE
ESTABLISHED BY
THE PUBLIC HEALTH COUNCIL OF THE STATE OF
NEW YORK
Condensed from the Bulletin of the New York State Department of Health
Isolation of Persons Affected with Communicable Diseases. —
It shall be the duty of every physician, immediately upon dis-
covering a case of communicable disease, to secure such isola-
tion of the patient as is required by the special rules issued
by the local health authorities or by the state department of
health.
Adults not to be Quarantined in Certain Cases. — When a
person affected with a communicable disease is properly iso-
lated on the premises, except in cases of smallpox, adult mem-
bers of the family or household, unless forbidden by the health
officer, may continue their usual vocations, provided such vo-
cations do not bring them in close contact with children.
Removal of Cases of Communicable Disease. — After isolation
by the local health officer no person, without permission from
him, shall remove, or permit to be removed from any room,
building, or vessel, any person affected with diphtheria, scarlet
fever, smallpox, or typhus fever.
Without permission from the local health officer no person
shall remove, or permit to be removed from any dwelling, any
person affected with chickenpox, diphtheria, epidemic cerebro-
spinal meningitis, epidemic or septic sore throat, measles,
mumps, poliomyelitis (infantile paralysis), scarlet fever, small-
pox, typhus fever, or whooping cough.
408
SANITARY REGULATIONS U
Removal of Articles Contaminated with Infective Material.
— Without permission from the Local health officer do person
shall remove, or permit to be removed from any room, build-
ing, or vessel, any article which has been Bubjecl to contami-
nation with infective material through Asiatic cholera, diph-
theria, scarlet fever, smallpox, typhoid fever, or typhus I
until such article has been disinfected according to the special
rules and regulations of the 3tate department "I health.
Exposure of Persons Affected with Communicable Disease.
No persons shall permil any child, minor, or other person
under his charge, affected with diphtheria, measles, scai
lever, smallpox, or typhus fever, i" associate with others than
his attendants.
No person affected with any of -aid diseases -hall e\p
himself in such manner as to render Liable their Bpread.
Exclusion from School of Cases of Disease presumably Com
municable. — It shall be the duty of the principal or other
person in charge of any public, private, or Sunday school to
exclude therefrom any child or other person affected with a
disease presumably communicable until such child or other
person shall have presented a certificate issued or counter-
signed by the health officer, stating that such child or other
person is not liable to convex infective material.
Exclusion from Schools and Gatherings of Children of House
holds where Certain Communicable Diseases Exist. — Evi
child who is an inmate of a household in which there is, oi
has been within fifteen days, a case of chickenpox, diphtheria
epidemic cerebrospinal meningitis, German measles, measl
mumps, poliomyelitis (infantile paralysis), Bcarlel fever, small-
pox, or whooping cmi-h. shall be excluded from every public,
private, or Sunday school and from every public or private
gathering of children tor such time and under >uch conditio
as may be prescribed by the local health authorities.
Precautions to he observed in Chickenpox. German Measles.
Mumps, and Whooping Cough. No person affected with
chickenpox, German measles, mumps, or whooping cough shall
410 APPENDIX B
be permitted to come in contact with or to visit any child
who has not had such disease or any child in attendance at
school.
Isolation or Removal in Smallpox. — It shall be the duty of
every health officer, whenever a case of smallpox occurs in his
jurisdiction, if a suitable hospital is available, to remove or
cause to be removed such case promptly thereto. Every in-
mate of the household where such case occurs, and every per-
son Avho has had contact with such case, shall be either
vaccinated within three days of his first exposure to the dis-
ease or placed under quarantine, and, when vaccinated, the
name and address of such inmate or other person shall be
taken and such inmate or other person shall be kept under
daily observation. Such observation shall continue until suc-
cessful vaccination results, or for at least twenty clays. If
such inmate or other person refuses to be vaccinated, he shall
be quarantined until discharged by the local health officer.
If there is no hospital available, the patient shall be isolated
and every inmate of the household shall be vaccinated or
strictly quarantined until discharged by the local health
officer.
Whenever a case of smallpox occurs in his jurisdiction, it
shall be the duty of the local health officer to use all diligence
in securing the names and addresses of all persons who have
had contact with such case, and in causing such persons to be
either vaccinated or placed under quarantine.
Maximum Period of Incubation. — Tor the purpose of this
code, the maximum period of incubation (that is, between the
date of the exposure to disease and the date of its develop-
ment), of the following communicable diseases is hereby de-
clared to be as follows :
Chickenpox 21 days
Measles 14 days
Mumps 21 days
Scarlet fever 7 days
Smallpox 20 days
Whooping cough 14 days
SANITARY REGULATIONS -11 1
Minimum Period of Isolation. — The minimum period
isolation, within fche meaning of this code, Bhall fc>
follows :
Chickenpox, until twelve days after the appearand the
eruption and until fche crusts bave Eallen and the scan are
completely healed.
Diphtheria i membranous CTOUp), Until two BUCCe881ve D(
tive cultures have been obtained from fche nose and throat at
intervals of twenty-four hours.
Measles, until ten days after the appearance of fche rash and
until all discharges from the nose, ears and throat hav<
appeared and until the cough has erased.
Mumps, until two weeks after the appearance of the d
and one week after fche disappearance of the Bwellin
Scarlet fever, until thirty days after fche development of fche
disease and until all discharges from the nose, ears and threat.
or suppurating glands have ceased.
Smallpox, until fourteen days after the development of the
disease and until scabs have all separated and fche Bears com-
pletely healed.
Whooping cough, until eight weeks after the development of
the disease or until one week after fche last characteristic
cough.
Sale of Food Forbidden in Certain Cases. — When a case of
diphtheria, epidemic or septic sore Jjhroat, amoebic or bacillary
dysentery, epidemic cerebrospinal meningitis, scarlet t«\
smallpox, or typhoid fever exists on any farm 01 dair\ ]
ducing milk, cream, butter, cheese, or other foods likely t<> be
consumed raw, no such foods shall he sold or delivered from
such farm or dairy, except under the following conditions ■
(a) That such foods are not brought into fche house wh
such case exists ;
(b) That all persons coming in contact with Buch foods eat,
sleep and work wholly outside such hous<
(c) That such persons do not come in contact in an\ way
with such house or its inmates ox contents :
412 APPENDIX B
(d) That said inmates are properly isolated and separated
from all other parts of said farm or dairy, and efficiently cared
for ; and
(e) That a permit be issued by the health officer.
Destruction of Foods in Certain Cases. — When a case of diph-
theria, epidemic or septic sore throat, amoebic or bacillary
dysentery, epidemic cerebrospinal meningitis, scarlet fever,
smallpox, or typhoid fever exists on any farm or dairy produc-
ing milk, cream, butter, cheese, or other foods likely to be
consumed raw, the state commissioner of health or the local
health officer may destroy or order the destruction of any such
foods which in his opinion may have been so contaminated as
to be a source of danger, and the local authorities may com-
pensate the owner for foods so destroyed.
Handling of Food Forbidden in Certain Cases. — No person
affected with any communicable disease shall handle food or
food products intended for sale, which are likely to be con-
sumed raw, or liable to convey infective material.
No person who resides, boards, or lodges in a household
where he comes in contact with any person affected with
bacillary dysentery, diphtheria, epidemic or septic sore throat,
measles, scarlet fever, or typhoid fever, shall handle food or
food products intended for sale.
No waiter, waitress, cook or other employee of a boarding
house, hotel, restaurant, or other place where food is served,
who is affected with any communicable disease, or who visits
in a household where he comes in contact with any person so
affected, shall prepare, serve, or handle food for others in any
manner whatsoever.
Cleansing, Renovation and Disinfection Required. — Ade-
quate cleansing of rooms, furniture and belongings, when
deemed necessary by the local health officer, shall immediately
follow the recovery, death, or removal of a person affected
with a communicable disease. Such cleansing shall be per-
formed by or at the expense of the occupant of said premises,
under the direction of the local health officer.
SANITARY REGULATIONS 413
Adequate renovation of premises, when <lf.-in.Mi n..-.
by the local health officer, sh.-ill immediately follow the i
ery, death, or removal of a person affected with a communi
disease. Such renovation shall be performed by and at the
expense of the owner of said premises or his agents under the
direction of the local health officer.
Adequate disinfection of premises, furniture and belongin
when deemed necessary by the h><-al health officer, shall im-
mediately follow the recovery, death, or removal of a \ ■•
affected with a communicable disease Such disinfection Bha 1
be performed by or under the direction of the local health
officer in accordance with the regulations of the Banitary o
and at the public expense unless otherwise pursuant to law.
APPENDIX C
"WHAT PEOPLE SHOULD KNOW ABOUT CANCER
Francis Carter Wood, M.D.
Condensed from the Bulletin of the New York State Department of Health.
Cancer not a Germ Disease. — The cause of cancer is still
unknown, but this does not prevent our being able to cure it.
The disease is quite unlike those due to germs, of which so
much has been learned in the last thirty years, and no germ
which is capable of causing cancer in human beings or in ani-
mals has been found. Cancer is, therefore, not contagious, and
there is no danger in treating or in dressing a cancer case.
Ordinary cleanliness, however, requires that the soiled dress-
ings shall be burned — not because there is any danger of
contagion of cancer, but because the discharges and dressings
contain germs such as those which cause boils, erysipelas, and
other skin inflammations.
Cancer not Contagious. — As cancer is not contagious there
is no reason to believe the stories, so often told, of " cancer
houses," or " cancer villages " or " cancer belts." The occur-
rence of a large number of cases of cancer in a house can
usually be shown to be due to the fact that the house has been
occupied by old people. Since cancer is a disease of old age
there will naturally be more cases of the disease in such a
house than in one which has been occupied by a number of
young people.
Cancer not Hereditary. — Cancer is not hereditary, although
much has been said and written about certain experiments with
strains of white mice to show that, by inbreeding, the occur-
rence of cancer in these animals is much increased. While
414
CAXCER 11.")
there is no question that tins is a fact, yel the increase can be
obtained only in certain strains of white mice, not in all varie-
ties, and lias never been observed in white rat tinea
rabbits, dogs, or other animals in which cancer occurs. There-
fore, there is no reason to worry because one member of your
family has suffered from cancer. It does no1 at all follow that
any other member of the family will have it. In a family the
members of which tend to be very long-lived, more cases of
cancer will occur than in one in which the members die young,
but this is not because can err is hereditary.
Cancer Attacks the Healthy. — CTnfortunately, cancer attacks
not only those who are in feeble health, but also, and with
equal frequency, those who are strong ami healthy ami h.
never suffered from any other disease. For tin- reason, it is
especially important that such healthy people Bhould consult
a physician if any sudden change in their well-being tak
place, and particularly if there is any digestive disturbance or
disorder of the bowels, for the stomach and intestines are fre-
quent sites of cancer.
AVe see, therefore, the unfortunate circumstances that while
the improvement in conditions of living has prolonged the lite
of the community on an average of ten years in the last cen-
tury, the same condition has apparently increased the number
of cases of cancer, since there are more people who reach the
cancer age than formerly. This gives more cases of cancer in
the population as a whole, though the relative proportion per
age group may not be increased.
How Cancer Begins. — While, as has been Baid, we do not
know the cause of cancer, we do know a g 1 deal about how
it occurs and what is apt to precede it. For instance, cancer
frequently begins in moles or warts which are irritated by the
clothes or are made to bleed and are kept Bore by repeated
injury of any sort. Such warts and moles are perfectly harm-
less at first, and become dangerous only after thej have been
irritated in this way tor a long time, especially if the person
is of the cancer age, that is, above forty-five yeai It 1- \\
416 APPENDIX C
therefore, to have such moles removed if they are in a situation
where they are liable to be rubbed or injured. It has been
found, also, that cancer frequently develops in the scar of an
old burn, or in places where there is a chronic ulcer, as on the
lip or tongue or leg, and care should be taken to see that such
ulcers are healed as quickly as possible.
Ulcers on the tongue and cheek frequently follow scratching
from a poor filling or from the sharp point of a decayed tooth,
and a dentist should be consulted if such an ulcer does not
heal within a few days, so that the filling may be properly
replaced or the point of the tooth hied off. Smokers should
be particularly careful about any sore on the lip or tongue ;
these are commonly found in those who use a pipe or cigars
and smoke so that the tissue is burned by the hot stem of the
pipe or at the point where the hot cigar smoke strikes, thus
keeping up a chronic irritation. For this reason, cancer of
the lip and tongue, while very common in men, is almost never
seen in women.
The beginning of an internal cancer is much more difficult to
determine, because small tumors just as they start cannot be
discovered except by accident ; but it has been found that they
almost always begin in some injury ; for instance, ulcer of the
stomach is a common cause of cancer, since the ulcers turn into
cancers if they are not cured by proper medical or surgical
treatment. So, too, cancers of the lower bowel are frequently
preceded by chronic inflammation, and persons suffering from
chronic dysentery, ulceration of the bowel, or bleeding piles,
should consult a physician to see that these troubles are cured
promptly and do not develop into cancer.
Cancer of the breast in women frequently follows chronic
inflammation, and is not caused by a blow, as is frequently
thought. Any woman who notices a lump in the breast should
at once consult a physician. It is very much better to be told
that the thing is harmless and need not be removed, than to
wait too long, only to find that it has already developed into a
cancer.
CANCEL' 417
Nature of Cancer. — Cancel is a \.t\ curious di • which
is due to the running awaj of certain parts of the bodj tissue,
that is, a few cells in the breast or in the liver or in anj other
organ grow beyond the natural limit and invade the Burroundi
tissues; then we have a cancer. This cancer often d • cot
give any notice of its presence until a 1 < • 1 1 .^r time r the
trouble has started, because the cells composing it are the Bame
(or nearly the same) as the cells from which they Btarted, and,
therefore, the body dot-s nol recognize the Eacl thai a cancer is
growing until it becomes of considerable Bize. It Btarts very
quietly, is very small at first, but gradually grows and destn
the very tissues that 1'rrd it, until ultimately it kills its fa
by injuring some important part of the body. I'-nt it is, in
such a case, the cells of the body itself which are the parasifr
in other words, there is no parasite introduced from the outside
to cause the cancer.
• Kinds of Cancers. — There are many kinds of cancer, and
each kind acts differently and spreads in it > own way through
the body. Certain forms which arise in glands, such as the
breast, are called carcinoma, and this sort spreads slowly t«»
places where there are small nodules of tis>ue>. called lymph
nodes, in which the cancer collects, forming there Beoondary
lumps or metastases, as the physician calls them. The true
carcinoma does not often get into the blood vessels, and there-
fore it remains localized for a very considerable time, bo that
the surgeon has an opportunity to remove it, it' the diagnoc
is made.
Another kind of cancer, called by physicians •<-',
spreads to the blood vessels and consequently is much ni'
difficult to cure, because this spreading takes place v. i\ early
in the course of the disease and the cells arc BWepf all 0\ er the
body, starting new little tumors where fchej are deposited.
While cancer grows through the very t: which surround
it, it does not have roots, as the quacks Bay. W hat are called
roots are more frequently blond vessels leading from the oan-
cer, or bits of fibrous tissue; so that when a quaes
418 APPENDIX C
patient that he takes a cancer out " by the roots," he is talking
nonsense.
Some cancers grow very slowly ; for instance, some of those
on the skin may remain for ten or twenty years without
spreading any very great distance and without forming little
lumps elsewhere in the body. Other cancers grow very rap-
idly and are fatal within a few months. Most cancers, however,
remain local for a considerable period, probably six months to
two years, before they really start to spread out in the tissues
and if only they can be discovered and cut out during an early
stage, the patient can be surely cured.
Symptoms of Cancer. ■ — Unfortunately, the very smallest
cancers give no symptoms unless they are on the skin or lip or
tongue or elsewhere on the surface of the body ; and in these
situations the earliest diagnosis can be made. Cancers the size
of a pea or but little larger are often diagnosed and removed
by a surgeon with an assured result, if the operation has been
properly done.
In the stomach and internal organs, however, the cancer
does not give rise to symptoms until it is quite large, and it is
important, therefore, for anyone who has any disturbance of
the stomach or intestines, loss of weight, or anemia, to go at
once to a surgeon, because by modern chemical methods and
by the use of the X-ray a diagnosis can often be made on one
of these cancers long before it can be felt or seen.
One of the last symptoms of cancer is pain ; this is due to
the pressure on the nerves by the growth spreading out through
the tissues. When a cancer gives a great deal of pain it is
usually beyond operation. Bleeding is a common result of
cancer of the intestines, and is one of the most important
symptoms. Every one should know, however, that when a
lump appears anywhere on the body, a physician should be seen
immediately ; the lump may prove to be an abscess or some-
thing quite harmless, for there are a good many tumors which
are quite harmless, or it may prove to be a cancer, and then if
it has been seen early enough, it can be cured by operation.
CAM EH \\\\
Occurrence of Cancer. - It has been Bhown l»v the Btudv of a
large number of cases of cancer in various countries, thai the
disease afflicts chiefly those of middle age, thai is, from fori
five to sixty-five years. Younger people and tho r eighty
years are rarely afflicted with cancer, excepl thai in very old
people various mild cancel's of the skin are no1 infrequent;
these, however, are easily cured by the X-ray or radium, and
do not need operation in all cases.
Women about the age of forty-five to fifty-five Bhould b<
careful, if any lump appears in the breast, to have a careful
examination made. Men of aboul this age, also, should be
watchful of ulcers on the lip, tongue, or inside of the che<
especially if the teeth are not good, and should have any Buch
ulcers immediately examined by a physician. The physician
may have to cut out a small piece and send it to a laboratory
in order to determine whether or not the growth is cancerous,
if it is too small to diagnose otherwise. It is very much betl
to have a diagnosis made early than to wait until the doctoi
sure that the thing is a cancer, for it is then often beyond
operation.
Treatment of Cancer. — The proper treatmenl of cancer i^
the removal of the growth as early as possible, it being re-
membered always that cancer is a local disease when it begins
and as a rule spreads through the tissues only after a consid-
erable time. The removal of small cancers or of beginning
cancers is often an easy matter and can be done under cocaine.
Internal cancers, of course, can be removed only by an exten-
sive operation; but the methods now are so successful thai a
very large proportion of the eases can be saved it operation
done early.
There is a popular impression thai cancer is incurable.
This is not so. Early operation cures Borne kinds of can.
for instance those of the lip, in about 96 per cut of the casi -
operated upon. If cancer of breast also could he operated upon
at an early stage, nearly tour fifths of the cases would remain
well. When operated upon at a late Btage, onlj one fifth
420 APPENDIX C
the cases are cured, that is, show no further appearance of the
tumor.
Eadium and X-rays are very good treatment for the small
cancers which appear on the faces of old people, and in some
cases may be very useful in helping to complete the surgical
cure by healing any small lump which appears after operation.
They are also the best treatment for a cancer which has gone
so far that it cannot be operated upon, and in such a condition
may frequently be of such benefit that the patient may live a
couple of years in comfort, but as a rule they do not cure can-
cer, and they should, therefore, never be used on a cancer of
any size ; instead, such a tumor should always be operated
upon.
Great care should be taken in selecting a physician to give
the treatment with X-rays or radium, because only a few per-
sons have enough radium for proper treatment, and only a few
doctors know how Jo administer without burning the patient
seriously, the large quantities of X-rays which are necessary to
produce good effects. It is better that a patient should go to
a hospital and get suitable treatment there, rather than to let
his local physician experiment.
The use of salve and other forms of treatment which are
widely advertised in the newspapers are worse than useless.
They often stimulate the cancers and make them grow more
rapidly ; or if they do eat off the top of the growth, they leave
the bottom spreading in deeply, and what is worse, result in
a waste of time, for the tumor should be operated upon
promptly.
Xo form of internal medicine will cure a cancer ; that we
know absolutely. Xor will any fluid injected under the skin
cure a cancer. Cases of cures by such means which are re-
ported in the papers or are talked about are merely instances of
mistaken diagnosis, for the quack relies upon the ignorance of
people as to what a cancer is and what it is not. Any small
lump is called a cancer by the quack ; then if it disappears he
will say he has cured it. As a matter of fact, a great many
CANCER l_'l
tests have been made of Hit- <;i m««t cures which are Bold in this
country, and none of them have been found to be of the slight-
est value in the treatment of real cancer, and real cancer is the
thing in which people arc deeply interested, because through
it their lives are in danger.
[NDEX
U> /< r< net s art to /"■•■
Abdomen, of crayfish . . . . 86
of grasshopper 13
Abnormal growth of tissue
cause of disease .... 233
Abomasum. division of Btom-
ach of sheep (ti^.) .... 154
Absorption, of food, defined 17.'!
of food not nourishment . l T ~»
Absorption in leaves of Ve-
nus's fly-trap 39]
Abstainers' record in -walk-
ing- match (fig.) .... 224
Acid secreted by roothairs . . 269
Acid medium in stomach . . 171
Aconite, a poison 221
source of 327
Acorn, a dry fruit (fig.) . . . 309
Actinozoa, example of ... <>
Active bacteria reduced in
number by heating milk Ml
Adam's apple 193
Adaptation, defined .... 161
student report on 162
Adaptations, of birds . . . . 138
of reptiles 1 •">!
Adductor muscles of clam
(figO • • • 95
Adulteration of foods . . . 180
Adventitious roots . . . . 284
experiments to show . . . . 404
Aerial roots, of corn .... 280
of ivy (fig.) 284
Aerial stems 286
Afferent fibers 213
Agar-agar, formula .... 346
plates (fig.) • • 348,349,360,351
Agave, section of epidermis
(fig-) 8«
Age of trees, how *.ld
Agencies of seed distribu-
tion 312
Agriculture, amount and kind
of cultivation in
as an industry
influence of mi civilization .
Air. home of bacteria . ... 344
Air cells of lung
Airspaces in stems, function
of
Albumen, examples of . . . 176
Alcohol, ambitioD destroyed b
a narcotic 221
;i poison 221
and disease 243
and patent medicines ....
canst- (if disease
chemical composit ion "f . . I7»'i
effect of. on circulation ....
<>n digestion 182
formed by yeast plant . . .
in bread driven off by beat , .
Protozoa and
vliorteii~. life 221
use of in consumption
Alcoholism a disease ...
Ale. manufacture of
Alfalfa, member "f pulse famil
rooi (fig.)
Algae, aquatic plants
example of 7
lark ..I conduct!] tern in .
number of 7
Alimentary canal, of fp
(fig.) 117.
of man (ti- | 161
Alkaline medium in mouth . 171
Alligator < l i ^ - >
nest
1
INDEX
References are to pages
Alligators, classified .... 7
described 133
example of reptiles .... 129
Alternate leaves, of beech
family 327
of nightshade family .... 331
of parsley family 329
of pulse family 329
of rose family 328
of walnut family 327
Alternation of generations,
in coelenterates 68
in ferns 372
in mosses 366
Althaea, member of mallow
family 329
Altricial birds, defined . . . 142
nest of yellow warbler (fig.) . 142
American elm, scientific name
of ^ . . 7
Ammonia in test for protein 265
Ammonium tartrate in Pas-
teur solution 356
Amoeba, classified 6
described 47
diagram of (fig.) 48
microphotograph of (fig.) . . 47
reproducing by fission (fig.) . 49
reproduction of 3
respiration of 49
Amphibians, described ... 113
economic importance of . . . 127
example of 7
laboratory study of .... 113
number of 7
summary of 127
Amphioxus, notochord of . . 104
Anatomy of starfish (fig.) . . 72
Anesthetic, defined .... 221
dissolves lipoid 223
Angiosperms, classes of . . . 7
defined 7
Animal biology 11
Animal cell (fig.) 4
Animal parasites, habits of . 233
Animal starch, in liver . . . 174
Animals, agents in distribution
of seeds 313
decomposed by bacteria . . . 345
without a backbone .... 6
Annelida, a class of worms . . 76
Annual rings, age of tree told
by 377
in longitudinal sections of
trunks 291
in stem of pine 377
Anopheles, mosquito (fig.) . . 42
cause of malaria . . . .42, 238
Antennae of grasshopper . . 14
Anterior adductor muscle of
clam 95
Antheridia of fern 371
of moss 365
Antheridial plant of mar-
chantia (fig.) 365
Anthers, described 296
Anti-pain medicines .... 246
Antitoxin, defined 351
described 252
in preventing spread of disease 246
use of in diphtheria .... 253
Ants, example of complete met-
amorphosis 19
social life of 41
Anus, in digestive system of man 169
Aorta, largest artery in man . 202
Aortic arches of earth-worm 82
Aphis, woolly (fig.) 25
Apiary, escape of bees from . . 35
model (fig.) 38
Appendicitis 168
Appendix, vermiform .... 168
X-ray photograph of (fig.) . . 169
Appetite, guide to amount of
food 180
Apples, a form of fruit . . . 310
example of pome (fig.) . 309, 310
produced by rose family . . . 329
value of as food 178
Aqueous humor 216
Arachnids, list of 91
Arbor vitae, cones of (fig.) . . 378
Arch, of foot 187
of hypocotyl of bean .... 264
Archegonia, of fern .... 371
of moss 365
Archegonial plant of mar-
chantia (fig.) 365
Arctic regions, adaptations for 161
plants of 396
INDEX
Reft r> run i
Arctic regions, continued
plants of , modifications of . . 397
use of lichens in 361
Arm, superficial lymphatics <>f
(fig.) 304
Arms, example of organ ... B
of starfish "_'
Army worm, harmful insect 28
Arsenic, a poison 232
Arteries, function of . . . L97, 201
in circulation of clam .... (.»7
of crayfish 90
of fishes 109
<ff man 201
Arthropoda, classified ... <»
example of 6
number of <>
word explained 86
Arthropods. Bummary of . . 93
Artificial respiration . . . . VX>
Aseptic, defined 347
Asexual reproduction, of
amoeba 3
of coelenterates <><>
Ash, result of chemical change . 9
Ash twig (fig.) 289
Asparagus beetles .... 26
Assaults and drink (fig.) . . 222
Assimilation, defined .... 2
in plants 279
Aster, a common weed .... 3.'i4
Atmosphere, composition of , '-1
Auditory organ of grasshop-
per 16
Auricles of heart 201
B
Bacillus, a form of bacteria . . 343
Bacillus tuberculosis, cause
of consumption 235
Bacteria, action on lava . . . 4<x>
and mold from bouse tly (fig.) ■ 251
carried by insects 315
cause of sour bread . . . • 179
classified 1
conditions necessary forgrowth 344
decomposition of materials by ■ '>}!
discussed
distributed by (lies ;;*7
art to /""/■
Bacteria, continut <t
etTect ni on medium on which
they gro*
fonns ol (fig.)
harm to teeth from p. 7
harmful
helpful
important plants ....
in formation of Soil . J"1
injury caused to bean plant bj
in relation to milk
in runts of beans .... 270,
in warm milk
laboratory b1 ody of ....
life processes of
multiplication of
proper conditions for growth of
shape and size
corkscrew (spirilla) ....
rod-shaped (bacilli) ....
round (cocci)
Soil (fig.)
Bource of disease 4"1
summary of . . ....
unfavorable conditions with-
stood by 346
where found 341
Bacterial growths on agar
plates (fig.)
Bacterial poison, toxin , . .
Bailer in gill chambers of
crayfish
Balanced ration 177
Balancing, use of tins for . . P>7
Balancing organ. .;ir a ■ . 218
Balaam, adventitious roots on i"i
Balsams, conifers
Bananas, value of M fond 17s
Barberry leaves i tiir i ...
Bark, function of
Barley, n cereal (figO ■ • • •
;t monocotj ledon ....
member of the grass family
0D6 Of the tirst plants culti-
vated
source of liquors ....
Barnacles, economic Impor-
tance of (fig.) "i. i"1
Baseball, advantage of M i nt-
eise
INDEX
References are to pages
Bass, a bony fish 106
example of fish 6
Bat, enemy of mosquito ... 42
hibernating (fig-) 151
Beaks of birds, variations in . 137
Bean, an irregular flower . . . 302
distribution of 318
early cultivation in America . 317
embryo, growth of 264
example of dicotyledons ... 7
field (fig.) 317
flower (fig.) 296
foodstuffs in 265
fruit of (fig.) 307
germination of (fig) .... 264
leaf, cross section of (fig) • . 273
pistil (fig.) 297
plant (fig.) 259, 267
injured by bacteria (fig.) . . 315
reasons for studying . . . 259
raising of 316
root, central cylinder of (fig.) . 268
cortex of (fig.) 268
epidermis of (fig.) .... 268
sections of (fig.) 268
showing tubercles (fig) • • 270
seed, laboratory study of . . 261
parts of (fig.) 260
relation to flower .... 297
seedling, parts of 267
stamen (fig.) 297
stem, laboratory study of . . 272
summary of 320
Bean and pea, photographs of
(fig.) 260
Bean blight 315
Bean family, members of . . 318
Bean -weevil, larvae of . . . 316
work of 315
Beans as food 178
cheapness of, compared with
meat 317
digestible • . . 317
for hogs or sheep 316
value of 317
Beans damaged by -weevils
(fig.) 315
Bee farms, escape of bees
from 35
Bee fly, a beneficial insect . . 41
Beech, value of
Beech family, description of .
Beech leaves, and buds of
(fig-)
Beechnut, a dry fruit (fig.) . .
Beef, value of, as food ....
Beef extract, in agar-agar . .
Beef jelly exposed, in sanitary
dairy (fig.)
in unsanitary dairy (fig.) . .
Beer, manufacture of ... .
use of yeast in making . . .
Bees, capturing a swarm of (fig.)
classes of
classified insecta
clustering at swarming time
(fig-)
complete metamorphosis of . .
cutting comb from hive (fig.) .
drone
gathering of nectar by . . .
honey, value of
imperfect female (worker) . .
members of Hymenoptera . .
nurses
perfect female (queen) . . .
swarming
wax, value of
Beet, a dicotyledon
roots of (fig.)
storage of food in
Beetle, May, a harmful insect .
potato, a harmful insect . . .
Beetles, classified
example of complete metamor-
phosis
field study of
Belladonna, compared with
stramonium
source of
Berries, produced by rose family
Berry, a form of fruit ....
collection of drupes ....
defined
illustration of (fig.) ....
pepo, special kind of ... .
Bichloride of mercury, use of
Bilabiate flowers of mint . .
Bile, a digestive juice ....
Biological diseases, kinds of .
327
327
327
309
178
346
350
351
355
354
37
f 35
6
36
19
39
35
297
39
35
20
36
35
37
39
263
283
283
26
26
20
19
12
331
331
329
308
310
310
310
311
253
331
172
233
i \ Di:\
Referenc* a ><>■■ to pa
Biology, defined 1
of disease 232
Birch roots, photograph ol
(fig.) 392
Bird house, plan for (fig.) . . lis
Birds, characteristics of . . . L36
classified 7
economic importance of . . . Ill
number of 7
summary of 149
Birds' feet, different kinds of
(rig.) 139
Bitter, a fundamental taste . . 165
Bittern, beak of 137
nest of 14'J
Bivalves, reason for name . . 98
Blackberry, in plant succession 4(H)
receptacle of fruit eaten . .
Blackbirds, food of
31,
310
14.")
132
207
294
257
197
Black snake, a constrictor .
Bladder
Blade of bean leaf . . .
of leaf, food storage in . .
Blind persons, number of .
Blood, corpuscles ....
of man 197
plasma 197
student report on '200
vessels, function of .... :'.
Bluebird, a beneficial bird . . 144
destroyed by hawks .... 145
destroyer of Lepidopt era . . 31
food of '-"J
Blue jay, at bread crumb sta-
tion 14S
at suet station 148
at whole grain station . . . 14'.i
feeds on larva; of Lepidqptera 31
Blue racer, a constrictor . . . 132
Boa-constrictor 132
Boards of health 246
Bobolink, female (tig.) ... 1 16
food of 11"
migratory habits of . . . 143
nesting habits of in
Body, parts of I
Body cavity of earthworm . 81
Body temperature, of birds . 138
of mammals 150
of man 190
Bone, microphotograpb of (flg.)
Bt rucl ure of ( t\g i
Bony fishes, list of
Borax, a preservative ....
Borers, harmful beetles . . .
eaten by downy \\ oodpecker
Boric acid, a preservative
Botfly, harmful Insect ....
Bottling-, good and bad (fig I
Bougainvillea hydroid [fig
Bracket fung-i, ctT.-ct on trees
Bracket fung-us (tiur) . . . .
Brain, conl rol (fig.)
efficiency, discussion of . . .
conditions Decessarj for . .
microphotograpb of ( fig >
" Brain " of earthworm . .
Braincase
Bran, used as an adulterant . .
Branch, example of organ
Branch infected with mis-
tletoe (fig.)
Bread, crumbs for feeding station
mold ( fig. )
laboratory study of . . .
rye, \ alue of as food ....
use of yeast in making
wheat , value id as food .
Bread-making, scientific Ka^is
of
temporary by-products of . .
Breathing, in grasshopper . .
in man
not respiration
Breathing center in develop-
ing embryo
Brewing, scientific basis of . .
Bronchus
Brook trout ( i'il: >
raised in hatcheries ....
Brown bat (fig.)
Brown creeper, at bread
crumb Btat ion
at suet stat ion
1 1 of
Brown hydra
Browntuil moths
Bryophytes clussitlod . ,
Bubbles of oxygen in masses
of spirogyra
106
111
11
218
212
- ■
lis
IIS
. U * i
17s
•
17s
11
l'.'l
22 1
ll Hi
111
152
lis
lis
111
I
•JO
6
INDEX
References are to pages
Bubonic plague, a bacterial
disease 2.34
Bud, in reproduction of yeast
plant 356
Budding1 (fig.) 287
Budding- cells of yeast . . . 356
Buds, a characteristic of stems . 286
Buffalo (fig.) 158
Bugs, members of Hemiptera . 20
Bullfrog 123
Bullhead (fig.) 105
organs of smell in 109
Bull snake, with hen's egg in
mouth (fig.) 130
after swallowing egg (fig) . • 130
Bull thistle (fig.) 396
Bumble bee, carrier of pollen
for red clover 304
economic value of 35
Burbank's work . . . .306,402
Burdock, common weed . . . 334
distribution of seed .... 312
by animals 313
in blossom (fig.) 311
Bur reed, a fruit distributed by
water 314
Bushman, environment of . . 127
Butcher bird, food of . . . 22, 26
Butter, example of fat .... 176
flavor of, due to bacteria . . 349
indirect product of plants . . 401
value of as food 178
Buttercup, characteristic mem-
ber of crowfoot family . . 327
study of pollination of . . . 305
Butterflies, classified . . . . 6, 20
complete metamorphosis of . 19
Butterfly, swallowtail, from
celery worm 34
larvae of 28
pollinating Persian lilacs (fig.) 299
Buzzards, food of 147
C
Cabbage, member of mustard
family 328
plant (fig.) 292
Cabbages, laboratory study of 404
storage of food in 294
value of as food 178
Cactus, giant (fig.) 395
Calcareous skeleton of coral 69
Calcium, a chemical element . 9
Calcium phosphate, in Pasteur
solution 356
Calla lily (fig.) 403
Calorie, defined 177
Calyx, described 296
Cambium, change to xylem . . 287
change to phloem 287
Cambium layer in woody stems 287
Camel, economic importance of
(fig.) 154, 158
Canada ginger, storage of food
in (fig.) . ... \ ... 291
Canada thistle (fig.) .... 336
Canal, alimentary, of frog
(fig.) 163
of man (fig.) 165
Cancer, quacks and 244
Cane sugar in Pasteur solu-
tion 356
Canine teeth 167
Canker worms 28
Canning of beans 317
Cap fungi (fig.) 357
Capillaries, described (fig.) . . 202
Capillarity 276
Capillary circulation (fig.) . 198
Capsule, a form of fruit (fig.) . 308
dehiscent fruit 310
fruit of lily 327
of moss 364
Capsule containing eggs of
earthworm 83
Caraway, member of parsley
family 329
Carbohydrates, a class of food 169
stored by bean 265
Carbolic acid, a disinfectant . 253
a poison 221
Carbon dioxide, a waste prod-
uct of respiration . . . . 3, 9
formed by yeast plant . . . 355
how obtained by water plants 394
product of respiration only . . 276
taken from the air by plants . 401
Carbonic acid gas, formed by
oxidation 9
Cardiac valve of stomach . 168
INDEX
Carnivorous plants, modifica-
tions of 389
Carpellate cone of pine . . .".7'.'
Carrier of disease 243
Carrion beetle, beneficial insert 26
Carrot, membei of parsley
family 329
storage of food in L's:;
wild, pollinated by fly (fig.) . '_)(.»s
Cartilage (fig.) 186
in skeleton 184
rings in air passages .... 193
where found 183
Casein, a form of protein . . . 1 T« i
Catalpa, wind-distributed plant
(rig.) 312
Catalpa twig- (fig.) 289
Caterpillars, destructive in-
sects 28
larvae of butterflies .... 19
stage in metamorphosis . . 17-19
Catfish (fig.) 105
Catkin-like flowers of wal-
nut 327
Catnip, a medicine 331
Cat-tails (tig.) 394
Cattle, escape inspection . . . 243
value of to man 154
Caudal fin of crayfish ... 87
Caudal region of lisli . . . 1«>7
Caustic potash in Fehling's
solution 265
Cecropia moth (fig.) .... :*>
Cedar, a conifer 383
Cedar bird feeding- young
dig-) ;;-
Celery, plant (fig.) 292
storage of food in 293
value of as food 178
Cell, animal (fig.) 4
name given by Hboke . . • 15
of plenroeoccus 339
plant (rig) I
unit of structure 4
wall . .
Cells, various forms of, in human
body (fig.) 189
Centipedes (fig.) 92
Central axis of pine cone . . 379
Central cavity of sponge . . 68
,tr- tO /""/■
Central cylinder of root
(fig.)
Central nervous system of
frog (fig.) 118
Central pith of wood
Central stalk of fern frond
Cephalopoda, classified . - .
Cephalopods, group of mol-
lu^k^
Cere
Cereal foods. Bouroe of . . .
Cereals < fig.)
list of
Cerebellum, of amphibians . .
of child
Cerebral ganglion of mollusk
Cerebral hemisphere of frog
Cerebrum of man
Certified milk, defined . . .
Chameleon, a li/;ird ....
Chara. food of craj fish . . .
Cheese, example of protein .
flavor of
indirect product of plants . .
value of as food
Cheese skipper
Chemical change, defined . .
Chemical compounds . . .
Chemical elements, propor-
tion of iu li\ iug tliin_'- | fig. i
Chemicals, used to enrich soil .
Chemical terms, explanation
of -
Chemical test for carbon
dioxide 275
Chest cavity of man . . 194, 201
Chestnut. :i dr> fruit (fig.) . .
trees, value of
Cherry, distribution of Beads of
twigs (fig.)
Chickadee. ;it hemp and millet
station n^
at BUel stati.'ti 148
at w hole grain station
destroyer ol md lai
oi Lepidoptera I
food of i>>
Chimney swifts, u- -t . . . Ill
u [ngs and feet of"
China, dependence on rice . .
ni
too
119
224
119
131
101
178
11
271
8
INDEX
References are to pages
Chinese silkworm
Chipping- sparrow, useful
bird
food of
Chloride of lime
Chloroform, example of anes-
thetic
action on lipoid
Chlorophyll, in leaves of bean
of pleurococcus
Chloroplasts, containers of
chlorophyll
Choroid, coat of eye (fig.) . .
Chrysanthemums, perfect
blooms of ....... .
Cicada, adult and nymph (fig.)
description of
member of Hemiptera . . .
Cigarette smoking", effect of .
Cilia, in air passage
of paramoecium
of sperms of moss, use of . .
Ciliata, classified
Ciliated larva, of liver fluke .
Circular muscles, of earth-
worm
Circulation, effect of alcohol on
in plants
of mollusks
organs of (fig.)
Civilization, advanced by agri-
culture
Clam, digestive tube of (fig.)
embryo of (fig.)
example of mollusk . . . .
laboratory study of ....
right shell of (fig.)
showing foot (fig.)
soft-shell (fig.)
Clams, artificial raising of . .
edible
example of pelecypoda . . .
fresh water
growing on oyster (fig.) . . .
Clasping base, of corn leaf . .
of grass leaves
Classification, basis of, in Pro-
tozoa
of birds ... \ ..... .
of plants by Linnaeus ....
28
144
31
253
221
223
272
339
272
216
226
25
25
24
227
195
50
366
6
77
80
205
278
97
199
326
95
97
6,94
96
95
94
100
100
100
6
94
101
281
323
52
139
303
of
Classification, continued
of seeds
of living things ....
Clean milk (fig.) . . .
Cleft grafting"(fig.) . .
Cleistogamous flowers
violet (fig.)
Clematis, twining petiole (fig.)
use of petioles in
Climbing plants, thigmotro-
pism in
Climbing stems compared
with trees
Clitellum of earthworm . .
Cloaca of frog
Clothing, obtained from mallow
family
source of
Clover, affected by darkness
member of pulse (bean)
family 317,
Club moss, related to ferns . .
sporangium of (fig.) ....
spores of (fig.)
uses of
Coal, formation of
study of, in connection with
ferns
Coating of hairs, use to Arctic
plants
Coats of pollen grain . . .
Cob, relation to corn grains . .
Cobra, most deadly snake . .
Cocaine, a poison
cause of disease
Coccus, a form of bacteria . .
Cockroaches, family of Or-
thoptera
harmful insects
Cocoanut, a fruit distributed
by water
Cocoon, of cecropia (fig.) . •
of codling moth . . . . . .
Cod, classified
example of bony fish ....
value of, as food
Codfish
Codling moth, a harmful Lepi-
doptera (fig.) 19
complete metamorphosis of
263
6
348
286
301
292
294
287
286
83
116
329
401
393
318
369
373
373
374
374
369
397
299
309
132
232
232
343
20
22
314
30
18
6
106
178
178
,28
17
INDEX
9
Codling moth, contintu d
description of •"•'_'
destroyed by downy w 1-
peckei ill
larva (rig.) 17
pupa (fig.) L8
Cce^enterates, examples of . . 63
described <'..'.
Coelome of earthworm . . . M
Coffee, effect on ln-art .... -^i,
Cold, a common disease . . 197
Cold-blooded animals . . . 109
Cold storage, purpose of . . :;);
Coleoptera, examples of . . . 20
Collar of corn leaf 281
Colonial Protozoa . , . . . 58
Colony, hydroids .... 66, <>7
Color of fungi, reason for . . 354
Colors, use of, in (lowers . 304, 389
Columbine, flower of (fig.) 304, 328
Use of .' 327
Communicable diseases . . 233
deaths from (fig.) 234
prevention of 239
Comparative cost of digesti-
ble nutrients 17s
Comparison of monocotyledo-
qous plants with dicotj ledo-
ikius 29B
of pleurococcus and spyTOgyra 341
of unicellular plants with mul-
ticellular 338
Complete flower, definition
of 297
also perfect : -it-
Complete metamorphosis of
insects 17. 19
Complex flowers of higher
plants W3
Complexion, light, 'lark . . . 190
Complex systems of higher
plants 103
Composite Family .... 334
Compound leaves, detineil . . 294
Condor 136
Conducting tissue of pteris
stem 370
Cones of pine (fig.) . 377, :;7->, .".7'.»
Conifers ( fig.) ;:To
general characteristics . • • 376
are t<< pages
Conifers, continued
related forms of
summary "f
Conjugation of spirok'y
(fig.)
Consumption, treatment of
Contact, movemenl caused bj
Contractile vacuole of
amoeba
Coon ( fig.)
Cooper h Hawk. > eonomii i
tils of
Copperhead snake ....
Copper sulphate, in Fehling's
solution
Coral islands, formation of .
Coral reefs
Corals, example of « kBlent
example of Ad Inozoa
Core, in pome fruits ....
Coriander, member of parsley
family
Corn, anionni produced In '
canned, \ alue of as f ood .
distribution of
emln-yo leaves of
example ol moi tj ledon ,
flower, described
flower w 1th pist ils I fig.) . . .
fruit of ( ti u: )
germination of (fig.) ....
indehiscenl fruits ...
kernels filled by corn smut ■ ,
laboratory Btud] of ....
leaf, description of
meal, value of as f 1
member of grass family . . .
one of first plants cultivated .
plant . prop roots of (1
plants, rootlet-, of i i'il: > . . .
product Ion, map of ....
raisin- as an IndUStTJ • .
Importance of
•• seed," comparison w ith bean
-red. diagram (1 ....
seedling
smut . a parasite on corn . .
a fungus
spores of i fig.) ....
Mem (fig. I
341
II".
•;
310
I
178
0
7
310
281
178
318
10
INDEX
References are to pages
215,
Corn, continued
summary of ... .
wind-pollinated flower
Cornea of eye (fig.)
Corolla, described
Corpuscles, red and white . .
Cortex of root (fig.) . . 267,
Cortical layer of kidney . . .
of root
Cotton, member of mallow fam-
iiy
production, map of . . . .
seed of (fig)
source of clothing
Cottony cushion scale . . .
Cotyledon of corn
Cotyledons, affected in bean
blight
of bean
importance of as food . . .
size of
storage of food in ... .
parts of seed
Cover crop, use of clover for .
Cow, example of mammal . .
stomach of
Cowbirds (fig.)
nesting habits of
Cowpox, Jenner and ....
Coxa, part of grasshopper's leg
Coyote (fig.)
Crab, soft-shelled (fig.) . . .
Crabs, classified
common name for crayfish . .
economic importance of . . .
example of Crustacea . . .
Cranium
Crayfish (fig.)
appendages of 86
bearing eggs (fig.)
circulatory system of ... .
digestive system of ....
example of Crustacea ....
food and food-getting ....
green glands of
laboratory study of ....
life history of
limited environment of . . • .
nervous system of
organs of (fig.)
321
305
216
296
197
268
207
267
329
332
313
401
27
263
315
260
261
261
261
301
270
7
154
147
142
251
16
150
91
6
86
90
6
118
87
,87
86
90
89
6
89
90
88
87
162
90
89
Crayfish, continued
respiration of 90
typical crustacean 86
Creeping- disk of snails ... 98
Creeping- stem, of trailing ar-
butus (fig.) 288
of Canada ginger (fig.) . . . 291
Crenate margins of mint
leaves 331
Cricket, member of Orthoptera 20
hai'mful insect 22
Crocodiles, distribution of . . 133
example of reptiles 129
Crop of earthworm .... 81
Cross-fertilization, changes
produced by 311
Cross-pollination, advantage
of
305
320
7
147
148
effect upon wild plants . .
Crow, example of birds . .
Crows, as scavengers .
at bread crumb station . .
at suet station 148
at whole grain station . . . 149
food of 22, 27, 31
in nest (fig.) 146
Crowfoot family, biting juice
of 328
characteristics of 327
members cultivated for orna-
ment 327
products of 327
Crustacea, classified .... 86
economic importance of . . . 90
Crustacea and related forms 86
Cryptogams, classified ... 7
defined 6
Cuckoos, food of .... 27, 31
Cucumber, example of pepo . 310
Cucumber tree (fig.) .... 379
Cud, stomach of animals that
chew the 154
Culex (mosquito) 42
•eggs and larvae of (fig.) ... 42
Culture, for protozoa .... 49
from clean milk (fig.) . . . 252
from dirty milk (fig.) . . . 252
of bacteria 244
Culture plates of agar-agar . 346
Curdling of milk, cause of . . 348
INDEX
1 1
/,■. t, r, net 0 an to pa .
Curd of milk 265 Deer, :i end cbewer l.M
Cure of plant disease . . . 320
Cures of quacks . . . . •_' II
Curing- of meat, purpose . . 347
Currant, example of berry . . 310
Currant worms, caterpillars . 19
Cuticle of paramcecium . . 60
Cuts, treatmenl of 204
Cuttlefish, a cephalopod . . . 99
compared with squid . . . 100
Cutworms, harmful inseel . . 28
Cyclops, a small crustacean
(fig.) 91
Cypress trees, conifers . . . 383
Cypris !U
Cytoplasm, of pleurococcus 339
of amoeba 48
of nerve cells 209, 225
of protoplasm
D
Daddy-long-legs (fig.) . . . 92
Dahlia roots (fig.) 285
Dairy cow, model (rig ) . . . '-'17
Dairy cows, number and dis-
tribution of (fig.) .... 249
Dairy stable, model (tig ) . . 248
Daisy, a common weed . . . '■•'■'A
a composite 334
white (fig.) 334
Dandelion, a common weed
(fig.) 334
a composite 334
distribution of seed (fig.) . • 312
Daphnia 91
Darkness, a universal stimulus :'>'.'.'<
effect of, on clover and ozalis 393
Darwin on cross-pollination
Davenport, quoted
Dead matter simplified by
bacteria 345
Deaf. Dumber of 257
Death caused by insects . ■ . 21
Deaths from communicable
diseases (fig.) 234
Decay, caused by bacteria ■ . ;;'i
Deciduous leaves, defined . 294
Decomposition caused by
bacteria -U4
305
256
l.v.
1
310
310
Must ration «>i .volution . . . 154
Virginia, faw as of (fig ■ . 156
Deer-mouse .i nocturnal ro-
dent i fig.) . . ....
Definitions of common bio-
logical terms
Dehiscent fruits defined , .
forms of (tig-)
Deliquescent stems ....
Denuded hills, cause ol
freshets
Deodorizers not disinfectants
Department of Agriculture
of United States, Inspect-
ing meal ....
in\ est i-'.i' iona concerning
cot tony cushion scale . .
Dependence, of fm
of mistletoe
of plants
Dermis, defined
Dero (fig.) M
Desert plants, living condi-
tions
Deserts, habitat of plants
Development of amphibians 120
Development of tadpole,
two stages In I ii-'. > . .
Devil fish, example ot cephalo-
poda
Dew. use by Bpermsof mosses .
Diamond-shaped markings
of marchantia
Diaphragm, of man (fij 194, 195
characteristic of mammals . l"-41
passage Of OeSOphagUS llir.>iiL;li 167
Diastase, enzyi >f fermenta-
tion
Dicotyledons, group of plants
represented by bean, squash,
etc
seeds of
Diet IT"
Digestion. ;i life proceed . •
completed In intestine • . •
described »71
effect of alcohol on IK2
in leaves of Venue's flj -trap
laboratory stud] of .... 173
123
12
INDEX
References are to pages
Digestion, continued
of food by pleuroeoccus . . .
of food in seed
Digestive fluids, of man . . .
of starfish
Digestive organs, of crayfish
of man, summary of . . 161,
Digestive system of animals,
student report on ....
Digestive tube of clam (fig.)
Dill, member of parsley family .
Dioecious flower, defined . .
Diphtheria (germ disease) . 197,
antitoxin 197,
thirty years of in N. Y. state
(fig-)
treatment of
Diptera (order of insects) . .
described
Direct heating (fig.) ....
Dirty barns, milk from . . .
Dirty milk, bacteria in (fig.) .
Disease, cause of
of beans (bean blight) . . .
of plants, necessity for know-
ing 320,
of respiratory tract ....
results of
student report on
summary of
Diseases caused by abnormal
growth of tissues ....
caused by bacteria ....
by plants or animals . . .
by poisons, list of ....
Disinfectants
Disinfection
Disk, central, of starfish . . .
sucking, of starfish ....
Disk-flowers of composites .
Dissected leaves of crowfoot
family
Distribution of plants ....
of plant products, an industry
of seeds, agencies for ....
of seeds by animals ....
by pappus and hooks . . .
by water
from milkweed (fig.) . . .
necessity for
339
266
171
72
89
182
164
95
329
299
234
252
242
252
20
41
197
348
319
232
315
402
197
254
256
258
233
401
233
232
253
253
71
73
334
328
399
401
312
313
389
313
313
311
Dividing cells of pleurococ-
cus
Dividing egg, becoming tadpole
(fig.)
of frog (fig.)
Division of labor
in man
in sponge
in volvox
Dodder, twining stem of (fig.) .
Dog, skeleton of (fig.) ....
Dogtooth violet, stems of . .
Dorsal blood vessel of earth-
worm
Dorsal surface of earthworm
Dough in bread making . .
Douglas fir. economic value of
Downy woodpecker, a perma-
nent resident
food of
Dragon flies, enemies of mos-
quito
member of Odonata ....
Dredging, necessity of . . .
Drills, a method of planting . .
Drink, impairment of scholar-
ship by (fig.)
skill and endurance impaired
oy (fig.)
Drink and assaults (fig.) . .
Drones (bees)
Drowning, a form of suffocation
Drupes, defined
Dry beans, ability of to grow .
Dry fruits, bean an example of
Drying, protection of bacteria
from
Drying fruit, purpose of . . .
Dry season, effect of on annual
ring
Dry seasons, effect of, on size
of cells . .
Ducks, feet of
E
339
122
122
56
164
57
56
288
150
285
82
80
179
385
141
144
42
20
387
402
221
219
222
35
196
310
264
310
345
347
290
Eagle, a scavenger
claws of ...
head of (fig.) . .
wings of . . .
378
137
147
137
140
136
ixi)i:x
13
Rqfen run b
Ear, affected only by Bound . . 21 1
balancing organ 218
membrane of froj; Ill
of grasshopper 11
pistillate flower of corn . . . 298
plan of (fig.) 218
sense organ 216
wax in L'ls
Earthworm, economic impor-
tance of 84
example of worms 6
excretions of 83
front end of nervous system of
(fig.) 82
illustration of true worms . . 80
laboratory study of .... 82
life history of 8.'5
locomotion of 80
limited environment of . . . 1<»'-
organs of (fig.) 81
respiration of 8ii
ventral surface 80
Easter lily (tig.) 300
pollination of 307
X-ray of (fig.) 327
Echinoderms classified . . 6
Economic importance of am-
phibians 127
of birds 114
of coelenterates "<>
of crustaceans 90
of earthworms 84
of fern group 374
of gymnosperms 384
of lichens 361
of mammals 164
of mollusks I'*"
of paramoecium 61
of plants 320
of starfish group 74
Economic insects 20
Economic interest in plants . 4<mi
Economic phases of grass-
hopper 22
Economic point of view in
study of plants .... 320
Economic value of mosses . 366
Ectoderm, of sponge .... 59
of hydra ,i:i
Ectoplasm of sponge ... 1^
.//•.' /<> page*
■ Edible clams, nam. •«, ..f . . . L0Q
Edible mollusks. Hal ..f . . . L00
Edible pulp of cherry, factor
in .list rihiit ion
Eels, migrations of 1 1'»
Efferent fibers 213
Efficiency centers of
brain 224,220
Egg, a reproducl i\ <• cell ... i
white of, example of protein
Egg-capsule of grasshopper
(fig.) IS
Egg cell (female parent) . . .
fertilization ..f. in plants . . 300
Vblvoi (fig.) 06
Egg-plant, a I i plant ..f night-
Bhade family
Eggs, of frog (fig.), develop-
ing 121, 122
of grasshopper (fig.) .... L0
of ladybug (fig.) 26
of Land-locked salmon (fig. ) .110
of moss plant 363
Egyptians, use of beans by , . -;1T
Elbow, normal and broken,
X-ray photograph (fig.) • ■ 180
Elk (fig.) 150
Elm. leaf (fig.)
twig (fig.) 289
Embryo, corn, position of • •
growth of, in o\ ulr .... ■"■"!
heart of
Of clam (fig. ) . 91
of coral
of Liver flake ""
parts of :;"i
Bac, content a of
vigorous, result of cross-polli-
nation 300
Employment afforded by
plant industries . . . . »oi
Enamel, effeel of bacteria on 167
Encystment of amoeba . . .
Endoderm, of root
of sponge
Endoplasm 18
Endosperm, food supply of corn
of corn uraiu
of coin, used for growth oi
dling
14
INDEX
References are to pages
Endurance and skill im-
paired by drink (fig.) . .
Enemies, of the bean ....
of corn
of lepidoptera
of man
Energy, source of, in man . .
yielded by bean
English sparrow, attracts
other birds
destroys weevils
eats larvae of Lepidoptera . .
permanent resident ....
scientific name of
English walnut, protein in . .
Enlarged base of onions, stor-
age of food in
Enriching the soil by nitro-
gen
Environment, denned ....
discussed
illustrated by development of
frog
Enzyme, of gastric juice . . .
of yeast plant
secreted by bacteria ....
Ephemeridae, an order of
insects
Epidemics, of diseases, costli-
ness of
sore throat (fig.)
Epidermal tissue of pteris
stem
Epidermis, of agave, section of
(fig.)
of bean root (fig.)
of leaf (fig.) 272,
of root
of rootlets
of xerophytes, character of . .
outer layer of skin
Epiglottis
Epileptics, number of ... .
Epiphytes, definition of . . .
habitat of
Epithelium, ciliated (fig.) . .
columnar (fig.)
flat (fig.)
Eskimo, surroundings of . . .
Esophagus, of crayfish . . ,
219
315
316
30
316
1
317
148
27
31
141
7
170
294
318
10
126
125
172
354
345
20
255
243
370
396
268
274
267
269
396
189
193
257
399
399
189
189
189
127
89
Esophagus, continued
of earthworm 81
of frog 116
of man 167
Ether, an anesthetic .... 221
test for oil 266
Eustachian tube (fig. ) . . . 218
of frog 114
of man 166
Evaporation, prevention of, in
experiment 295
Evaporation of perspiration,
effect of 190
Evergreen, leaves defined . . 294
trees, examples of 286
Evergreens, characteristics of 376
Evolution, theory of .... 123
Examples of plant societies 393
Excitable temperament,
heart tracing 228
Excretion, a life process ... 2
definition of ...... . 3
in crayfish 90
of hydra 65
of man 206
of mollusks 97
Excurrent stem of ever-
greens 286, 377
Exercise, benefits of .... 195
necessary to keep one fit . . 240
value of 204
Exercising, out of doors . .' . 194
to keep well 351
Exhalent pores 58
Exhalent siphon of clam . . 94
Exoskeleton, of crayfish . . 88
of grasshopper 15
of lobster, molted (fig.) ... 87
Experiment, to show produc-
tion of carbonic acid in plants 275
performed on plants .... 403
Expiration, defined 194
Explosion of fruit case to
scatter seeds 312
Extinct animals, remains of . 125
Extinct plants, remains of . . 125
Eye, section of 216
Eyeball 215
Eyelid 215
Eyes, of fish 109
INDEX
15
/.'•/• n nee*
Eyes, continued
of frog lit
of grasshopper 11
of man, care of 217
of Nereis .si
of vertebrates 215
F
Faeces, removal of 17."
Fainting-, cause of 208
Fangs of rattlesnake . . . 233
Fats, absorption of 174
furnished by animals .... 17"
nutrients 1
Fawns of Virginia deer (fig.) 166
Feathers, a characteristic of
birds 136
of birds, modifications of skin 190
Feeble-minded, number of . , 257
Feelers, of bullhead .... 109
of grasshopper 14
Feet of birds, different kinds
of (tig.) 139
Fehling's solution, formula . 265
test for sugar 266
Female bobolink (fig.) .... 14">
grasshopper (rig.) 11
strobilus of pine .">7(.»
Femur, broken (fig.) . ... 187
of grasshopper L6
Fennel, member of parsley
family :v_,(.i
Fermentation, cause of . . . 350
effect of 345
produced by enzymes .... 345
tubes (tig.) 355
Fern, forked veins of (fig) . • 371
garnet ophyte -;7l
life history (fig.) . . . .371,372
Fern group, plants belonging to 373
Ferns, example of pterido-
phytes 7
field study of 373
habitat of •"'<'•,.,
laboratory study of .... 373
Ferns and their Allies . . . .".o'.i
in relation to water .... 375
summary of 375
Fertilization, defined . . . 68, '-"•>'.,
are to pagt *
Fertilization, continued
"i egg ••ell in the o\ iii.- . . ,
of frog
Fertilized egg cell, beginning
of new organism
of volvox
Fertilizers, use of, to supply
elements
Fibers in blood
Fibrinogen, in format ion of
clot
Fibrous roots, of buttercup
(fig.)
of corn
of grasses
Fibrovascular bundles, cells
of
in leaves
in root
structure of
use of, in photosynl bests
Field study, of f.-rn^ . . . .
of gymnosperms
of insects
Field suggestions, mammals .
Filaments, described ....
Finches, beak of
Fin rays
Fins, of ftah
use of, in balancing and steer-
ing
Fires, forests destroyed by . .
l>iv\ .niion of, by national g
eminent
Fire slash (fig.)
Fire train in the Adiron-
dacks (fig.)
Fireweed in plant bu< ssion
Firewood, furnished by b
family
Fireworks, ose of spores ol club
iiio>s in
Firs, conifers
Fish, care of young
skeleton of I fig. I
mi in ma rv of
Fish hatcheries
Fishes, bony
circul.it ion of
classified
121
271
a . i
i^n
12
137
107
1"7
107
100
112
112
lb)
106
109
8
16
INDEX
References are to pages
Fishes, continued
food-taking 108
reproduction of 109
respiration of 108
scales of (fig.) 107
special senses /)f 109
with lungs 106
Fish fry, young (fig.) .... Ill
showing volk sac (fig.)
Ill
Fission, a form of cell division 49, 339
Flaccid cells 273
Flagellata, group of Protozoa . 53
Flagellate protozoa (fig.) . . 52
Flat worms, classified . . 6, 70
Flavor, improvement of . . . 311
of butter 345,349
Flavors caused by fermentation 345
by bacteria 345
Flax, family 329
requires cultivation .... 329
useless parts of plant removed
by bacteria 345
Fleas, member of Siphonaptera 20
Flesh-eating animals . . . 161
Fleshy fruits 309
Fleshy stalks for storage . . 294
Fleshy stems for food storage . 285
Flies, carriers of bacteria . . 347
classified 6
members of Diptera .... 20
Flipper of seal 152
Floods, cause of 385
damage caused by 386
prevention of 385
Florida alligator (fig.) ... 133
Flour, food elements in . . . 179
Flower, of Columbine (fig.) . . 304
of corn with pistils (fig.) . . 299
of mallow (fig.) 331
of mint (fig.) 303
of sweet pea (fig.) 298
violet, cleistogamous (fig.) . . 301
Flower bud 289
Flowering plants 323
common families 323
summary of 336
Flowering sage, adaptations
for insect pollination . . . 304
Flowerless plants, classifica-
tion of 7
food
Flowers, field and laboratory
study of
of bean, organs
wind-pollinated . . .
Flycatcher, great-crested
of
Flycatchers, eaters of larvae .
food of
Flying squirrel (fig.) ....
Fly pollinating wild carrot
(fig-)
Foliage, rank-scented leaves of
nightshade family ....
Food, a vital condition . . .
care of
definition of
first plants to be cultivated for,
list of
for reindeer in Arctics . . 361
fungi a source of
necessary to keep one fit . .
of animals, student report on .
of bacteria
of clam
of plants, study of
of snakes
of starfish — how taken . . .
pecuniary value of
storage — Canada ginger (fig.)
stored in cotyledons of bean .
Food-getting by animals . .
by grasshopper
Foods
Foodstuffs in bean ....
Food-taking of earthworm . .
of starfish
Food vacuole
Foot of moss sporophyte . .
Foraminifera, one of the (fig.)
Forest fires, harming of soil by
Forest reserves . .
Forestry in Europe
Forests, extent of in U
importance of . .
patrolling ....
proportion necessary
tall trunks of pine in
Forked veins of fern (fig.)
Formaldehyde, a preservative
gas
302
260
305
26
31
145
152
298
334
314
240
169
326
, 366
354
240
171
344
96
320
132
73
177
291
261
2
14
1
265
84
73
48
366
52
387
387
387
385
385
387
385
377
371
348
253
i.\i)i:.\
Refert net b
Formalin, in milk 180
used as disinfectant .... 'J.V.
Fossils, described 124
shells of animals qow extinct
(fig.) 124
Foul breath caused by bac-
teria KIT
Foxes (fig.) 151
Fox sparrows, transients . . 141
Fox terrier, comparison of
primitive horse with . . . 154
Freezing1, protection of bacteria
from 345
Fresh air, a condition for health 240
aid in curing consumption . . •_'■">•;
Freshets, cause of 386
Fresh-water planarians . . 7(i
Frog", bull, development of . . L23
central nervous system of (fig.) 118
common (fig.) 114
description of 113,114
eggs (tigs.) 120, 121
example of amphibians ... 7
enemies of 115
food of 115
green, development of . . . 123
habitat of 114
internal structure of .... 115
laboratory study of . . .114, 120
leopard, description of ... Ill
organs of (fig.) 11<>, 117
reproduction of 117
respiration of 115
tree (fig.) 126
Fronds of pteris 370
Fruit, buds of cherry (fig.) . . 289
defined 308
of apple (fig.) 309
of beau (fig.) -;i|7
of bean and corn 308
of corn (fig.) 307
of pine
of poppy (fig.) ■"■"*
production in connection with
storage roots 283
steps in de\ elopmenl of . . • 308
Fruits, distributed by animals
• tig.) 311
by wind (fig.) 312
distributers of seeds . . . . 311
by
are to pagt
Fruits, tontinvu
furnish luxuries of food •
new varieties produced
cross-pollination .
of rose family
w itli hooks (fig.)
Fruits and seeds in- i . . .
Fry. distribution of
Fuel, hardwood 1 1 lurce of
Fumigants
Functions, definition of . . .
Fundamental tissue of pteris
stem
Fung-i, action in changing lava
1" --oil
classified 7
conditions favorable for
growth
summary of
Fungus, an enemy of corn . .
Furniture, lumber for ....
Furs, as clothing
::il
401
.11
Ml
111
1
362
291
G
Gall bladder of i !.>_' .... 117
Gall flies, example of ll\ menop-
tera 20
Gametes, defined 341
of moss
Gametophyte or sexual gen-
eration of moss ....
Gametophytes of moss . .
Ganglia, of clam
<>f earthworm
Garden slug, shell of ....
Garden vegetables, belonging
to mustard family .
to parslej family ....
Garter snake, harmless
Gas, a form of matter ....
use in bread making ....
Gastric gland (li-. i , . 169,171
Gastric juice 171
Gastric mill, of crayfish . .
Gastropoda rlussinVd . . .
Gtoese, feel "t 137
wild, t ransientfl l '1
Gelatinous secretion of
earthworm
18
INDEX
References are to pages
Genera Plantarum, published
by Linnaeus 303
Geometrid moth (rig.) ... 32
Geotropism, defined .... 284
Geranium, life processes of . . 259
simple leaf of 294
slip, roots of 284
study of flowers of 302
Germ, a name for unicellular
organisms 343
diseases 233
Germination, laboratory study
of 265
of corn (fig.) 277
Germs 233
a name for bacteria .... 343
in dust in houses 235
of disease carried by insects . 21
Giant cactus (fig.) 395
Gila monster, poisonous lizard
(fig.) 131, 135
Gill, cover 107
Gill rakers 108
Gill scoop, of crayfish .... 90
Gill slits 104
Gills 107
of clam 96
of crayfish 90
Girdle, pectoral 105
pelvic 105
Gizzard of earthworm ... 81
Gland of starfish 72
Glandular hairs of sundew . 390
Glassy sponge, skeleton of . . 61
Glomerulus of kidney . . . 208
Gluten changed by heat . . 179
Glycerin formed by zymase 179
Glycogen, stored in liver . . 174
Gnats, eaten by birds .... 145
Goats, economic importance of 154
Golden rod, a common weed . 334
Goldfinch at hemp and millet
station 148
Goldfish, a typical bony fish . 106
killed by tobacco smoke . . . 230
Gonium (fig.) 55
Gophers, harmful mammals . 155
Government inspection, of
meat 78, 242
of oyster beds 102
Grafting, effect of 402
kinds of (figs.) .... 286, 287
Grain, differs from bean . . . 262
food for birds 149
of corn, a form of fruit . . . 310
Grains, large numbers of . . . 314
Grantia classified 6
described 58
Grape, example of berry . . . 310
Grapevine, wild, like liana . . 287
Grass family 323
compared with rose family . . 328
Grass, life processes of . . . 259
monocotyledon 263
wind-pollinated flower . . . 305
Grasses, flowers of 323
importance of, as food . . . 400
in plant succession 400
Grasshopper, classified ... 6
classification of 19
described 12
foot of 16
hairworm in body of (fig.) . . 79
injurious to corn plants . . . 316
laboratory study of ... . 13
laying eggs (fig.) 15
life history of 15
member of Orthoptera ... 20
mouth parts of (fig.) .... 14
parts of (fig.) ....... 13
representative animal ... 1.1
structure of 19
Gravity, influence of, on roots . 284
Gray squirrel (fig.) .... 151
Gray substance of nerves . 211
Great-crested flycatcher,
food of 26
Great northern shrike, winter
visitant 141
Grebe (fig.) 136
Greeks, use of beans by . 317
Green Algge 338
Green frogs, development of . 123
Green hydra, habitat of . . . 66
Green manure 270
Green manuring 318
Green turtles 131
Gristle, defined 184
Groove, on underside of starfish 73
Grosbeaks, beak of 137
INDEX
19
Ground birds, wind's «>f . . . 136
Grouse, a seed eater . . . . 117
at whole grain station . . . 1 19
Growth of bean embryo . . 264
Grubs, larvae of beetles . . . 19
of bean weevil - • l * >
Guard cells, of fern Btomata 373
of stomal a 273
Gullet, of paramoecium . . . 50
Gulls, sailing birds 136
herring ( fig.) 137
Gums, effect of tartar on . . . fi.7
Guttation drops, defined . . -74
Gymnosperms, by-products of 384
classified 7
discussed 376
field study of 383
reason for name 381
student report on 383
use of 384
Gypsy moths, injurious insects 28
H
Habitat, of evergreens .... 381
of mosses 364
of Protozoa 46
Habits of plants, of interest to
fanner 402
Haemoglobin in corpuscles . . 197
Hair, origin of 190
Hair snakes 78, 79
Hair worm 7 s
in body of grasshopper (fig.) . 79
Hairs on leaves of Venus's
fly-trap "''.'1
Hairy woodpecker i fig.) . . H7
Halibut, value of as food . . . ITS
Hand, superficial lymphatics ol
(fig.) . • • •' 204
Hard palate 166
Hardwood, forests, described . 388
trees, large flowering plants . 323
Harmful bacteria 343
Harvest-man, harmless arach-
nid 91
Hawk, Cooper's 148
example of bird 7
marsh 146
red-shouldered 148
are to /"'.'/■
Hawk, contin
red-tailed
sharp-shinned
Hawks, beneficial birds ami
claw s of
Hawkweed, a common weed
Hay infusion for protozoa
Head, of fish
ol grasshopper
ol rat t lesnake book lug p<
glands (fig.) . .
of young eagle (fig.)
Headache medicines
Head end of earthworm . .
Heads, inflon bc< nee of compos-
ite family
Head-thorax region of cray-
fish
Headwaters of rivers pro-
tected
Health
Healthy bodies and bacteria
Hearing-
Heart (fig.)
and lungs (fig.)
center
nuisi le ••■■Us t fig. i
of craj fish
valves of
Heart and blood-vessel-
man
Heart-shaped body, prothal-
lium oi fern
Heat and pressure. Influence
of in forming coal ....
Heating1, common methods
hot air (fig.)
milk, eft. ct of on bacteria . .
strain (fig.)
protection of bacteria from .
Hedge nettle iti-. >
Heel of man .......
Hellebore, sourer of • •
Helmholtz on alcohol . . .
Helpful bacteria
Hemiptera. discussed ....
order of insects
Hemlock, bark, use oi
Colics Of (fig.)
conifer
143
148
1 .7
•
19
13
l l
l»<>
Sii
•:
218
201
22 1
190
197
187
10
20
INDEX
References are to pages
Hepatica, example of incom-
plete flowers
Heredity, discussed
of disease
Hermit crabs, economic impor-
tance of
Herons, beak of
Herring, economic importance of
Herring- gulls (fig.) ....
Hibernation, defined ....
study of
Hickories, members of walnut
family
Hills, a method of planting . .
Hilum of bean
Hinge of clam
Hinge ligament of clam . . .
effect of starfish on ....
Hinge teeth of clam . . . .
Hip bones of man
History, of bean plant ....
of corn plant
Hogs, fed on beans
inspection of
Hollow bones of birds . . .
Hollow stem, of horsetail . .
of parsley family
Hollyhock, member of mallow
family
Home making, work of women
Home study of moths and
butterflies
Honey, amount of carbohydrate
in
locust, seedlings of (fig.) . .
made from nectar by bees . .
value of in U. S
Honeybee, discussed ....
stages in development (fig.)
worker, queen, drone (fig.) . .
Honeybees clustering at
swarming time (fig.) . .
Hoofs of cattle, origin of . .
Hooks, on fruit of burdock . .
on seeds, use of
Hookworm disease ....
Hop lice destroyed by lady-
bugs
Hops, use of, in manufacturing
of beer
302
125
255
91
137
106
137
115
159
327
402
260
96
96
73
96
187
317
320
316
243
138
374
331
329
257
33
170
281
297
39
34
35
34
36
190
313
389
239
26
355
Horehound, a medicine . . . 331
Horned pout (fig.) 105
Horned toad, a lizard (fig.) 129, 131
Horns of cattle, origin of . . 190
Horse, classified 7
discussed 153
evolution of 154
use of 155
Horse-chestnut, compound
leaves of 294
seedlings (fig.) 281
twig of (fig.) 288
woody stem 287
Horse-radish, member of mus-
tard family 328
Horsetail (fig.) 374
joints of stem 374
Horsetails, members of fern
group 373
related to ferns 369
Host, defined ....... 31
of liver fluke 77
Hot air heating (fig.) . . . 195, 196
House flies, eaten by birds . . 145
Housefly (fig.) 41
bacterial growths from (fig.) . 250
bacteria and mold from (fig.) . 251
House sparrow, scientific
name for 7
Houses, source of materials for 401
Human biology 161
Human stomach, X-ray photo-
• graph of (fig.) 168
Humming birds, beak of . . 137
summer residents 141
Humor, aqueous 216
vitreous 216
Humus destroyed by fires . 387
Hydathodes, defined .... 274
Hydra, cell layers in (fig.) . . 65
diagram of (fig.) 64
example of coelenterate ... 6
laboratory study of ... . 66
microphotographs of (fig.) . . 63
microphotographs of body wall
of ... 64
Hydra-like animals described 63
summary of 70
Hydras, examples of coelente-
rates 63
ixi)i:x
21
/,' f{ rerun a
Hydrastis, source of ... . 327
Hydrochloric acid in arti-
ficial gastric juice . . . 173
Hydrogen, proportion of in
plants and animals .... 8
Hydroid. bougainvillea (fig.) »>o'
colony thai Looks like a plant
(fig.) 67
medusa (fig.) . . » .7
obelia microphotograph of
(fig.) 66
Hydroids, described .... <;<;
examples of coelenterates . • 63
Hydrophytes, definition <>f . . 394
finely divided Leaves of sub-
merged forms 394
waterlilies (rig.) 393
Hydrotropism, detined . . . 284
in roots 284
Hydrozoa, classified .... 6
Hymenoptera, discussed . . :'«l
order of insects 20
Hyphae of bread mold . . . .V>7
Hypocotyl. pari of embryo . . •"•||i
part to grow first 261
use of, to embryo 261
I
Ice, a form of water .... 9
use of , in caring for milk . . .".is
Ice cream, dangers from . . . 350
manufacture of 350
Ichneumon flies laying eggs
in trees (fig.) W
Ichneumons, discussed . . . 39
enemy of Lepidoptera . . . . 28
members of order Hymenop-
tera .... 20
Imbecility 232
Immunity 26S
denned 251
Immunization 'S<-
Imperfect flower, kinds . . 302
of corn 298
Improvement of plants,
methods of W2
Incisor teeth 166
Incomplete flower, part lack-
ing in $•-
/" pages
Incomplete metamorphosis
ol tree cricket (fig.)
Indehiscent lr .
Independence of plan
Independent existence
moss gametophyte .
India, dependence "n i .
Indian pipe
Indians, use <>f beans bj .
environment of .
of
Indigestion
causes of
tablets for
Indirect heating (fig.) ■ . .
Indistinct ring.left by bud scales
produced by droughl ....
Inefficiency, caused !>y tempo-
re iv sickness
Influence of alcohol on de-
velopment of brain . .
Infusoria
Inlnilent pores
Inhalent siphon of clam . . .
Inhalers
Inherited diseases ....
Inner chamber of eye ui.
Inner coat of pollen grain
Inner ear (tig.) .... JIT,
Inoculation
Inorganic foods
Inorganic matter
Insanity
16
17
••1
1.7
180
181
196
Insect, group, divisons of
pollination
\ Lsitors, Btudj of
Insecta
Insect enemies of bean plant
Insects, acti\ [ties of . . . .
carriers of bacteria . . . .
de\ ices for attracting . . . .
examples of Arthmpoda
field study of
life bistorj "i
nhjeet iii \ isit tng tl"\\ en
Inspection of meat
Inspiration, defined
Insulation of nerve ftbei
Integument, development
of bean
of o\ ales
M
172
10
\\i
12
194
301
•
22
INDEX
References are to pages
Intercellular spaces .... 274
Interdependence of plants . 361
Internal gills 122
lungs 122
structure of earthworms, labo-
ratory study of 82
Interrelationship of animals 61
Intestine 168
Invertebrates 6, 103
Inverted image 217
Involuntary muscle cells
(fig.) 189
Iodine test for starch . . . 265
Iris of eye (fig.) 216
Iron 9
Irregular corolla of saliva . 304
Irregular flower of violet . 302
Irregular flowers, denned . . 302
Irritability 2
Ivy, adventitious roots of . . . 404
aerial roots of (fig.) .... 284
Jack-in-the-Pulpit, storage of
food in stem of 285
Jaw bones of fish 106
Jaw of man 166
Jellyfish, example of coelenter-
ate 6
belonging to hydra group . . 63
Jenner, vaccination 251
Jewelweed, explosive fruit of . 312
Jimson weed, member of night-
shade family 331
Juice of mustard family,
characteristics of . . . . 328
Juice of the buttercup, char-
acteristics of 328
Junco (fig.) 144
at hemp and millet station . 148
at suet station 148
Katydids, a family of Orthop-
tera 20
Keel of bird's breastbone . . 138
Keeled sternum of bird . . 138
Kernel, comparison with bean
pod 262
Kidney, section of (fig.) . . . 207
Kidneys of frog 117
King bird (fig.) 145
food of 145
Kingfisher, nesting habits of . 142
(fig.) 146
Koch, discoverer of Bacillus tu-
berculosis 235
of tuberculosis test .... 349
study of bacteria by ... . 351
Laboratory experiments
with leaves .... 275, 295
Laboratory study, of bacteria 346
of bean seed 261
of bread mold 360
of ferns 373
of foodstuffs in seeds .... 266
of grasshopper 13, 16
of gymnosperms ... . 384
of leaves for storage .... 404
of live fish 107
of moss 366
of moth and butterflies ... 33
of pleurococcus 339
of pollination of flowers . . . 305
of protozoa 50, 53
of reptiles 135
of roots 271, 285, 404
of seed dispersal 314
of seeds 263
of skeleton 188
of spirogyra 341
of sponge 59
of starfish 73
of stems 404
of tasting 166
of twigs 291
of wood 384
of worms 81
of yeast plant 356
Lacteals 174
Lactic acid, effect of ... . 348
Ladybug 26
eggs of (fig.) 26
Lady slipper (figs.) . . 303, 397
/ VDEX
23
Lampreys
Land-locked salmon, eggs <>i
(fig.) 110
Land snail let
Larch, a conifer
Large cells, position of In an-
nual ring 286
Large intestine 168
Lark, meadow ill
Larkspur, medicinal plant . . 327
Larva, o I codling moth (fig.) . 17
of mourning cloak butterfly
(fig.) • .' 28
Larvee. of bean weevil .... 316
of leaf miner in elm leaf (fig.) • ;,,1
Larynx 193
voice box (fig.) 194
Lateral bud 288
Lava, change to soil .... 100
Lead, cause of disease .... 232
Leaf, buds of cherry (fig.) . . 289
epidermis of (fig.) 274
of elm (fig.) •-".'!
of oak (fig.) 294
scars, defined 289
skeleton (fig.) 273
Leaflets, of compound leaf . . '-"-'J
of fern frond 373
Lean meat, example of protein 268
Leather 1 •"».">
indirect product of plants . . 401
Leaves, of bean 260
of ferns '• 369
of grass, shape of 398
of ivy, arrangement of . . . 398
of mosses 364
of pine, described 378
of pitcher plant (fig.) .... 390
of seed .• 260
of trees, arrangement of . • . 398
Leaves and bud of beech ( fig.) 327
Leech 76
Leeuwenhoek, improver of mi-
//./. /■• no i ore to pagt i
. . 106
in changing
Hi »sci ipe
:y>o
Legs and wings of birds . • 136
Lens of eye (tig.) 216
Lenticels. described .... 287
Leopard frog ill
Lepidoptera 20
Lianas, defined 2W
Lichens, action
lava to soil
epiphj tic habit of
field study of
(fig.) •. . . .
flection -•: ■ B1
Life history, ol tern it:
ol grasshopper 15
of oyster, Btagea in • : _ . . 101
of the mosses i fig. i . .
of the plant, defined . . .*
Life processes it
of bacteria
Light, a universal stimulus . .
a" vital condition
Lilac, yellow swallowtail butter-
th gathering oectai from
(fig.)
Lily family
Lily-of-the-valley (fig.) . . .
Linden twig (fig.)
Linen, furnished by tfax fami
Bource of clothing i"l
use of bacteria ba manufactur-
ing
Lingual ribbon
Linnseus, work of
Lions
Lipoid :
Lips of frog 11"'
Liver 117
Liver flukes 77
Liverworts 7
Lizards 131
horned toad, example of • I g 129
Lobes, olfactory .... .lis
optic . . . ' 119
Lobster
molted eX. .skeleton of I fig.)
Lockjaw
Locomotion
Locust
Loggerhead shrike (fig |
Longitudinal muscles
Long-spurred vude:
- of sei D
Lumber, from gymnosperms
t r<'iu hardwood trees
furnished bj walnut tan j
ho* cut
SO
24
INDEX
References are to pages
Lumbering, in New York (fig.) 380
operations, forests destroyed
by 387
Lungs 3, 117, 192, 193
and heart (fig.) 193
Luxuries, fleshy fruits ... 311
of food from rose family . 328, 401
Lymph 203
Lymphatic circulation . . . 204
Lymphatics, superficial, of arm
and hand (fig.) 204
M
Mackerel, a bony fish .... 106
value of, as food . . . ." . 178
Maggots, larvae of flies ... 19
Magnesium, a salt 173
Magnesium sulphate in Pas-
teur solution 356
Main arteries, of frog (fig.) . 202
of man (fig.) \ 203
Malaria 42, 237
caused by mosquito .... 238
protozoan disease 234
Malarial parasite, source of . 238
Malarial swamp (fig.) . . . 238
Mallard duck, skeleton of (fig.) 138
Mallow, family, importance of 329
flower of (fig.) 331
Malt, formation of 355
Mammals, classified .... 7
discussed 150
number of 7
report on 155
summary of 159
Man, example of mammal . . 7
Mandibles (fig.) .... 13, 14, 41
Mantle 94
Map, of corn production . . . 319
of cotton production .... 332
of potato production .... 335
of production of oats .... 324
of production of orchard fruits 330
of wheat production .... 325
Maple, seedlings, cotyledons of . 282
development of (fig.) . 279, 280
syrup 385
trees, products of 385
twig (fig.) , . 289
Maple sugar industry, in Ohio 385
in Vermont 385
Marchantia (fig.) 367
Marsh hawk, partly harmful .
Martins, mosquitoes eaten by .
Massasauge, a rattlesnake . .
Masts, use of gymnosperms for
Material for clothing . . .
Matter, organic and inorganic
145
42
132
384
329
9,10
163
Maturity, a period of life
May beetle, injurious insect
(%•) • • • 26
May flies, member of order
Ephemeridae 20
Meadow lark, food of . . . 147
nest of 141
Mealy bug (fig.) 25
Measles, probable cause of . .234
Measuring worms, cater-
pillars 19
Meat 10
indirect product of plants . . 401
lean, use of, as food .... 176
Mechanical tissues of pteris
stem 370
Median fins of fish 107
Medicinal members of crow-
foot family, list of . . . 327
Medicines furnished by
crowfoot family .... 327
Medulla, of frog 119
of man 224
Medullary layer of kidney . 207
Medullary rays, in woody
stem 289
of pine 378
Medullary sheath of nerve . 211
Medusa, described 67
hydroid (fig.) ....... 67
pelagia (fig.) 67
Melons, example of pepo . . . 310
Mendel, Gregor, study of peas 125
Mendelian laws, defined . . 126
Menhaden, example of bony
fish 106
Mental inefficiency, cause
of poverty 257
Mercury poison . . . . 221,232
Mesentery of frog 117
Mesoglea of coelenterate . . 63
INDEX
25
Mesophyll of leaf 273
Mesophytes. ilfiiniiiuii .,1' . . 397
Mesothorax of grasshopper 16
Metal container dangerous
for milk 300
Metamorphosis 16
complete 17
incomplete 16
Metathorax of grasshopper 16
Metazoa, defined 66
Method of pollination, basis
of classification •"-<>•">
Meyer. Hans, discovery of . . 223
Mice, destroyed by hawks 145, 14<»
harmful mammals 166
Microbes, a name for bacteria . 343
Microphotograph. of bone
(fig.) L86
of brain (fig.) 212
of conjugating spirogyra (fig.) 341
of corn stem (fig.) 279
of hydra (fig.) o"'>
of stomach (fig.) 170
of sun flower stem (fig.) . . . 286
Micropyle, of bean 261
use of 300
Microscope, inventor of . . . 350
Microscopic animals and
plants 233
Middle ear (tig.) . . . . 217,218
Middle West, production of
corn by 318
Midrib of marchantia . . . 367
Migration of birds .... 143
Milk, care of 350
card of , example of protein . 266
from healthy cow . Dumber of
bacteria in 347, 348
good and bad hottlinu i t'iL,r.) . 362
indirect product of plants . . 101
value of, as food 178
Milk glands, characteristic of
vertebrates 150
Milk teeth (fig.) 166
Milkweed, fruit (fig.) .... 312
plant distributing seeds (fig i 313
Milkweed butterfly ....
Milt of fish Ill
Mineral matter in food ... 1
Mineral substances .... 179
on to j"i'/' §
Mink, harmful mammal . . .
Mint, flower ol ....
Mint family, charactei
Mints used for medic ;d
in food
Mistletoe, absorbing orgaus ol
a Bemi-parasite I
branch infected \\ ith (rig.) .
Mites, arachnids 91
parasitic
Mixed diet of man .... 170
Model, dairj cow i fig, i . . .
dairy stable (fig . , . 248
resen oir (fig.) . . . . . 'Jin
Modified cotyledon (scutel-
liu f corn
Modified leaves, of club m.>->
of husks of corn
of |><-;i plant (fig.)
Moisture, a condition for
growth of bacteria .... 34 \
a Bl imulus
a vital condition 315
for lichen gathered by fungus ,
Molars of man 167
Mold, grown from water (fig I
Molds, classified 7
Moles destroyed by hawkfl . \\'<
Mollusca. classified
number of
MoUusks, characteristics of . . M
life history of
Bhells of, home of hermit crab 91
summary of 1"'-'
Molt, defined 16
Molting, discussed
Monarch butterfly (fig | 20
laboratory b( udy of ....
Monkey, example of mammal . 7
Monocotyledons, group of
flowering plants 7
represented bj com
Beeds of .
Monoecious flower, defined
Of beech family ....
of w alnnt famih
Morning glory, a climbli
plan!
a dicotj ledon
sc. (iiin--, of US
26
INDEX
References are to pages
Mosquitoes, breeding places . 41
members of Diptera .... 20
Moss, composition of cushion of 364
two generations of 366
Mosses, and their allies . . . 3(54
classified 7
general features 364
habitat 364
life history of (fig.) .... 3(55
number of 7
types of (fig.) 364
Moths, carriers of pollen . . . 304
example of Lepidoptera ... 20
Moths and butterflies, field
study of 33
Motile cells (sperms) of moss
plants 365
Motor function 213
Mourning" cloak butterfly
(fig.) 29
Mourning- dove (fig.) .... 143
Mouth, cavity of earthworm . 81
of man 164
parts of grasshopper (fig.) . . 14
Movements of plants . . . 392
Mucus, use of, by clam ... 96
Mucous membrane .... 182
Muscle, bundle 188
Muscle cells, heart (fig.) . . 189
involuntary (fig.) 189
voluntary (fig.) 188
Muscles, color of 188
involuntary 188
of man . . , 184
of upper leg (fig.) 188
scars of clam 96
voluntary 188
Mushrooms, edible fungi . . 354
poisonous 233
Mustard, a common plant fam-
ily ....... . .323
Mutton, value of, as food . . .
Muzzling of dogs
Mya arenaria, edible clam . .
Myriapods, discussed ....
Myrtle warbler, at suet station
328
178
250
100
92
148
N
Nails, origin of 190
Narcotic, defined 221
Nasal cavity of fish .... 109
Nasturtium, twining petiole of
(fig-) 292
use of petioles in 294
Natural gas, formation of . . 375
Natural laws, basis of success
in agriculture 320
Nectar, relation to pollination
by butterfly 30
sought by insects 297
use of, to flowers 389
Needle-like leaves of pine 377, 378
Nephridia of earthworm . . 83
Nereis, an annelid worm ... 84
Nerve cells (fig.) .... 209, 211
of mollusks 98
Nerve fibers, defined .... 209
description of 211
gray substance of 211
white substance of 211
work of 210
Nerve pathways in midbrain 119
Nerve trunk 222
Nerves, cranial, of frog ... 119
location of 119, 210
of earthworm 82
of frog 118
of mollusks 98
Nervous system, function of,
in locomotion 2
growth of 211
of crayfish 90
of earthworm, front end of
(fig-) 82
of frog (fig.) 118
of man (fig.) 209, 210
parts of 209
summary of 230
Nest, of bittern (fig.) .... 142
of chimney swift (,fig.) . . . 144
of yellow warbler (fig.) . . . 142
Nest-building of birds . . . 142
Net-veined leaf 272
Nighthawks, destroyers of
mosquitoes 42
food of 145
Nightshade family, character-
istics of 334
Nissl bodies 225
Nitric acid, test for protein . . 265
/ \ DEX
27
i: /< !■■ run t
Nitrogen, a chemical element
gathered by bacteria . . . 270, 318
in lipoid 222
proportion of In living thin. '.•
Node of corn stem .... 281
Nomenclature of plants by
Linnseus 303
Non-motile cells (eggs) of
moss plants 366
Non-productive persons,
Dumber i>r 257
Non-smokers, scholarship of . 229
Normal body temperature
of man 190
Nose. Bense organ 215
Notochord, embryonic struc-
ture of fishes .... 103, 106
Nourishment, defined . . . 1T."»
in beans 317
Nuclei of pollen and egg- (tiur.) 300
Nucleoli of cells .".
Nucleus, of cell 268
of nerve cell 209
of pleurococcus 339
Nurses, care of bee larva.* by . :"><>
Nuthatches, at snet station . 148
at hemp ami millet station . . I 1 ^
destroyers of Lepidopt era . . '.1
useful birds Ill
Nutrients, defined 1
Nuts, from hardwood trees . .
furnished by walnut family 327
indebiseent fruits 310
Nymphs of cicada (fig.) . . 25
O
Oak, leaf (fig.) 294
trees 327
Oatmeal, value of as food . . 178
Oats, a cereal (fig.) 326
a monocotyledon
map of production of . . . . 324
member of grass lamik . . . 326
value of as food 178
Obelia, classified 6
microphotograpb of (fig.) • • 86
Obnoxious plants, nanus of •
Octopus, example of mollusk M
member of cephalopoda ( liu'-i • '•''•,
Odonata. order of . .
Odor, use "( in flowers
Odors, of other f Is absorbed
by milk
produced bj fermentation
Oil, tests for
Oils, a class of foods . .
Old agre. a period in lift- li
Olfactory lobes, function ..f
of frog (fig.)
One-celled plants . . .
Onions, storage •■! food in
Operculum of fish . . .
Opium, a poison ....
Optic lobes oi f p.- nij lis.
Optic nerve di-. i . . . . 21<>,
Oral side of starfish ....
Oranges, a form of fruit . . .
example of berry
section "i | tii: )
value oi as i 1
Orbits, defined
Orchard fruits, from I u-
iiy
mail of production of .
Orchids, greenhouse epiphj
pollinated by moths ....
Org-an. defined
pa it 1. 1' body
Organic matter, example of
Organism, beginning of Den
Btudj "I
Bensat ion in
Org-ans, of bean ■ •
of circulation (fig . .
of cia\ lish
of earthworm (fig. > . . . .
of frog (figs.) 1 16,
Of plants
Org-an system, defined .
part "f bod]
Orioles, food of , •
nest of ... .
Orthoptera. order of Insect!
Osmometer flg.)
Osmosis, defined .
bomemade apparatus for show -
log ....
in absorpt ion »1 i 1
in photos) uthcsit)
l
II .
IP'
in;
11''
JIT
310
213
\
1"
»
M
117
t
1
142
28
INDEX
References are to pages
Osmosis, continued
in root hairs 269
in sponges 58
Outer coat of pollen grain . 299
Outer ear (fig.) 217, 218
Outer skeleton, of crayfish . . 88
of turtle 130
Ovary, of coelenterates ... 68
of frog 118
part of pistil 297
Overwork, predisposes to tu-
berculosis 240
Oviducts, of frog 118
of horned toad 131
Ovules, change to seed . . . 300
described 297
of pine 379
Owl, feet and beak of ... . 137
screech (fig.) 138
snowy, a winter visitant . . . 141
Oxidation, defined 1, 9
in birds 138
Oxygen, a chemical element . 8
a condition for the growth of
bacteria 344
proportion of, in living things 8
use in respiration 3
use of, by birds 138
Oysters, artificial raising of . 100
barnacles and clams growing
on (fig.) 101
destroyed by starfish .... 74
examples of mollusks .... 94
stages in life history of (fig.) . 101
value of, as food 178
Pain 213, 215, 232
Palate of man 166
Palisade cells of leaf .... 272
Panama Canal, a health prob-
lem 239
Pancreas 169, 172
Pancreatic juice, enzymes in . 172
Pansy, capsule of 310
cleistogamous flower .... 302
Paper, made from spruce trees . 384
Papillae of tongue 165
Pappus, use of 389
Paraffin, in transpiration ex-
periment 295
Parallel venation, of corn leaf 282
of leaves of lily family . . . 326
of grass leaves 323
Paramoecium 6
diagram of (fig.) 50
example of ciliata 6
mode of defense 51
reproducing by fission (fig.) . 51
resisting attack (fig.) .... 51
study of 50
Parasites, action of 233
group of fungi 354
ichneumons 30
liver fluke 77
plants, modifications of . . . 389
tapeworms 76
Thalessa 39
Parasitism, a dependent rela-
tion 403
Parsley family, characteristics
of 331
list of plants in ..... . 329
Parsnips, member of parsley
family
storage of food in
Partridge, wings of ....
Passer domesticus, scientific
name of English sparrow . .
Pasteur, discoverer of lactic
acid bacteria
study of bacteria by ... .
Pasteurization, denned . . .
Pasteurized milk tested for
bacteria
Pasteur solution, formula of .
Patent medicines, defined . .
to be avoided in consumption .
Patrolling of forests ....
Paupers, cost of supporting . .
Pea plant, modified leaves of
(fig.)
member of bean family . . .
seedlings of
Peaches produced by rose
family 329
Peach-tree borer 28
Peanut, peculiar habit of (fig.) . 318
Peanut shucks as adulterant 180
329
283
136
348
350
349
347
356
244
237
387
258
294
317
282
INDEX
29
Referenct a
Pears, example of pome . . . 310
Pear scab (figs.) 359
Peas, Mendel's experiments <>n . 125
Pectoral girdle of vertebrates 105
Pedal ganglion of clam . . 96
Pelagia, a medusa (fig.) • • • 67
Pelvic girdle of vertebrates 106
Pelvis, of kidney 207
of trunk of in;iii 207
Penguins, use of wings . . . 136
Pennaria, classified ('»
tiarella (fig.) 68
Pennyroyal, a medicine . . . 331
Peony, use of :<l'7
Pepo, special form of berry . . 311
Peppermint :;.".l
Pepsin in gastric juice ... 171
Peptone in agar-agar formula 346
Perch, a bony fish (fig.) . 104, 106
classified •;
Perfect flower, definition <>f . 297
Perianth of lily family . . . 326
Pericardium, of clam .... 97
of man 201
Permanent teeth (fig.) . . . KIT
Persian lilacs pollinated by
swallowtail butterfly (ti v.) 299
Perspiration, amount of, how
regulated L90
a waste product
use of 190
Petals of bean flower . . _".»*;
Petiole, length of 389
of bean leaf 272
of clematis (fig.) '_".»_'
of nasturtium (fig. ) . . . . '_".i2
Petroleum, format i f. . . 375
Petunias, members of night-
shade family 331
Phanerogams, a group of plants c, 7
Pharynx, of earthworm ... Bl
of man 164, l»'»o
Pheasant, a seed eater ... 1 17
wings of 1 •'••'»
Phenolphthalein test for acid 21 M '
Phlegmatic temperament,
heart tracing of (fig.) . . ,
Phloem, carrier of food . . • 271
conducting food materials • . '-"•',|
constituent of green bark . 287
are to pagi
Phloem, contintu d
pi '-it ion in w I\ -t .-m .
position of in \ ascnlar bundle
Phaebes, destroyers "f Lepidop-
tera
Photosynthesis, finished prod-
net of
<-\ \ gen produced bj ....
performed bj stem ....
\ ital process In plants
Phosphates 176,
Phosphorus, a chemical ele-
l
menl found in li\ ing thing*
a poison
in lipoid
179
useful in body
Phylum (Phyla i groups of
plants and animals ... 7
Physical change described .
Pieplant, storage <>i food in . .
Pigment in skin
Pigs, important mammals 151
Pike, a bony ti>h !<*;
raised in hatcheries . . . . ill
Pill bug (fig.) 9]
Pine, example of gymnosperm . 7
pollen of (fig I 57
ripe cone of i fig. )
seed Of ( fig.)
ataminate Bl robill of (fig.)
t ree, described 77
parts of
Pine grosbeak at hemp and
millet station n*
Pine siskin at hemp and millet
station 148
Pinnae of fern frond ....
Pinnately compound leaves
of walnut family ....
Pistil, described
diagram of
Pistillate flower, described
of monoecious plant
of willow (fig)
Pitch, souree of . . .
Pitcher plant
leaves ol (fig
use of leaves In
Pith in corn stem ....
Plague of locusts ....
30
INDEX
References are to pages
Planarian worm (fig.) . . 76, 77
Plant, biology ....... 259
cell (fig.) 4
conditions, change of ... . 400
ecology, definition of ... . 399
food, of interest to farmer . . 402
lice 41
injurious to corn plant . . 316
members of Hemiptera . . 24
on fern (fig.) 24
protected by ants .... 41
life, mystery of 404
peculiarities of 389
or animal matter food of bac-
teria 344
poison 233
Plant-eating animals . . . 161
Plant societies 393
Plant succession 400
Plantation in the Adiron-
dack^ (fig.) .... 385, 386
Planting- young- trees in the
Adirondacks (fig.) .... 384
Plants as organisms, interest
in 402
Plants decomposed by bac-
teria 345
Plasma 203
Plecoptera, order of insects . 20
Pleurococcus, appearance of
(fig-) 338
described 338
example of alga 7
group of cells 339
where found 338
Plum, example of drupe . . . 310
produced by rose family . . 329
Plumage, discussed .... 139
Plumule, connection with seed
leaves 261
defined 260
part of embryo 301
Pneumonia 234
Pod of bean 260, 308
Poison, defined 221
in tobacco smoke 230
Poisonous character, of crow-
foot family 327
of lizards — Gila monster (fig.) 135
of snakes 132
character,
con-
Poisonous
tinned
of toxins 345
of plants of nightshade family 331
Pollen, cell (male parent) . . 299
distributed by wind .... 305
of pine (fig.) 387
produced by stamens .... 297
sacs of pine 379
tube, formation of 300
of pine 381
Pollen grains growing
through pistil (fig.) ... 300
Pollination, by wind .... 305
definition of 297
step in the production of fruit . 308
Pollution of -water .... 247
Polytrichum, laboratory study
of 366
Pome, a fleshy fruit (fig.) . . 309
Pond scum, habitat of . . . 339
Pome fruits, defined .... 310
Poppy, capsule of 310
fruit of (fig.) ....... 308
Pores of sponge 58
Porifera, classified 6
Pork, inspection of 78
trichinella in 77
value of as food 178
Posterior adductor muscle
of clam 95
Potassium, a chemical element
found in living things ... 9
contained in food 173
Potassium permanganate, a
disinfectant 253
Potassium phosphate, in Pas-
teur solution 356
Potato, a food plant of the
nightshade family .... 331
(fig.) 285
beetles, injurious insects . . 26
blight, a fungus 360
production, map of .... 335
response of, to light .... 393
value of, as food 178
Poultry, destroyed by certain
hawks 145
Preecocial birds, defined . . 143
nest of bittern (fig.) .... 142
/ VDEX
31
/,' /< r< nces
Prairie dog's, harmful mam-
mals 160
Prairies, suited to raising <>f
corn 318
Praying- mantids, a family of
Orthoptera Jit
Predigested foods, use of . . 181
Pre-molar teeth, discussed . . 167
Preparation of foods, dis-
cussed 177
Preservatives, list of . . . . 348
Preserved substances . . . 347
Preventable diseases . . . 234
Prevention, of communicable
diseases '_'•">'. »
of plant diseases 320
Primary root of bean . . . 267
Prisoners, number of ... . 257
Proboscis of butterfly . . . 29
Propolis, use of, by bees . . . 37
Prop roots of corn (fig.) 278, 280
Protective coloration. of
birds 139
of grasshopper 14
of moth (fig.) 33
Proteid substances in flour.
source of food for yeast plant 358
Protein, a class of foods . . . 169
in bean 317
product of photosynthesis . . 276
stored by beau *_'»i".
Prothallium of fern, a gameto-
pbyte 371
Prothorax of grasshopper . Hi
Protonema of moss .... : 165
Protoplasm, of cell . . . . 5,208
of pollen grain :'><><)
Protozoa, cause of disease . . 237
classified <">
flagellate (fig.) 52
number of kinds of .... •'.
resemblance to bacteria . . . 343
simplest animals 15
Protozoa and alcohol . . .
Protozoan cell, described . . 16
Protozoan culture .... 19
Psalterium, division of stomach
of sheep (fig.) 154
Pseudopodium of amoeba 17
Pteridophytes, classified . • 7
an to pugi
Pteris, described (t ...
stein (fig.)
Ptomaines, in Ice cream . .
Public institution
tion of servants for . . . 244
Puff ball, example of Coi
(fig.) :
Bpores of, " Bmoke "
Puffins. nest of 142
Pulmonary tuberculosis, dis-
cussed
Pulse, caused i>\ beating ol
heart
Pulse, members of bean family,
tnenl loned in Bible ....
Pulse family, characterise
of
discussed
foods furnished i>>
li^t of plants of
\ alue to soil of plants of .
Pumpkin, example of pepo ■ .
Pumpkin seed, a f i — 1 * (fig.) . .
Pupa, a Btage in metamor-
phosis of insects
description of
of cecropia i tiur.)
of codling moth (fig.) . • • •
Pure culture, defined ....
Of J east
Pure food laws
Pure milk, cosl of producing
Purple finch, at hemp and mil-
let station 1 18
Purple sea urchin .71
Pyloric valve of stomach . .
Python, a constrictor ....
MX)
311
104
18
18
18
180
Q
Quack defined ....
. . :\\
Quail, a seed eater . . .
117
at w hole main -.tat ion
149
- — » — •
Quarantine, defined
•.'17
laws
.
violation of
2 17
Queen bee (fig.) ....
d. 0
1
. .
32
INDEX
References are to pages
R
Rabbits, destroyed by hawks .
harmful animals
young (fig.)
Radial arrangement of star-
fish
Radish, a dicotyledon ....
member of mustard family . .
roots (fig.)
storage of food in
Range of plant's territory,
how increased
Rank-scented foliage of
nightshade family . . .
Raphe of beans
Raptores, discussed ....
Raspberry, in plant succession .
canes killed by tree crickets .
distribution of
produced by rose family . . .
Rattlesnake, a poisonous snake
(fig.)
discussed
head of (fig)
poison, effect of
rattles of (fig.)
Rats, destroyed by hawks . .
harmful animals
Raw materials of photosyn-
thesis
Raw milk, danger from . . .
Ray flowers of composites .
Rays of starfish
Rectum, part of digestive
system
Red bud, member of pulse fam-
iiy
Red clover pollinated by
bumble bee
Red corpuscles of blood . 197,
Redheaded woodpecker (fig.)
Red poll, at hemp and millet
station
Red rust of wheat, a fungus .
Red-shouldered hawk . . .
Red-tailed hawk
young of (fig.)
Red- winged blackbird, food
of
145
155
154
71
263
328
282
283
312
334
261
140
400
22
313
329
132
132
131
233
131
145
155
276
350
334
72
168
329
304
198
28
148
360
145
145
140
22
361
Reflex action, discussed .
diagram (fig.) ....
in the earthworm . . .
in the frog
in the hydra
Reforestation ....
Refrigeration of foods .
Regeneration, defined
Regular flowers, defined
of mustard family . . .
Reindeer, food of . . .
useful animal
Relationships of plants an
interesting study . . .
Remedies, plants a source of .
Report on twigs
Reproduction, a life process .
asexual, defined
of amoeba
of bacteria
of grasshopper
of hydra
of paramcecium
of yeast plant
simplest form of
Reproductive bodies of
pteris
Reproductive glands of star-
fish
Reproductive hyphse of
bread mold
Reptiles, discussed
life history of
summary of
Reptilia, classified
number of
Reservoir, model (fig.) . . .
poor (fig.)
Resin, source of
Respiration, described . . .
artificial, described . . . .
in man
organs of
of amoeba
of bean plant
of grasshopper
of hydra
of mollusk
of paramoecium
of starfish
212
212
214
214
214
387
240
75
302
328
,366
154
403
401
293
2
3
49
345
15
65
51
356
339
371
72
357
129
129
135
7
7
240
241
384
2 3
196
192
192
49
275
15
65
97
51
74
/ \ DEX
li< /■ n n& | an to pa
Respiration, contimu <>
produces carbonic acid gas . 276
studenl report <>n 192
Respiration, blood, and ex-
cretion 192
Rest, effect of, in consumption , 236
necessity for, in keeping well . 240
Resting- stage (pupa) of cod-
ling moth 19
Restricted diet of primitive
life 170
Reticulum, division of stomach
of sheep (fi^-) 164
Retina (fig.) 216
Rhizoids, of marchantia . . . 367
of mosses 364
Rhizomes 286
Rhizopoda, classified .... 6
Rhododendrons, insect visitors 34
Rhubarb (pieplant) storage of
food in 293
Ribbed stems of parsley-
family 331
Rib of leaf 272
Bice, amount produced in lr. S.
member of grass family . . .
use of, in China and India . .
value of, as food
Right shell of clam (tiur.) . .
Rind of corn stem 281
Ring of cambium in woody
stems 287
Ripe cone of pine (tiir-) . . . 378
Ripened ovary, the fruit of a
plant 308
Robber bees 36
Robin, a useful bird Ill
food of 27
often a winter resident (tig.) . 141
Rochelle salts in Fehling's
solution 265
Rock oil, formation of . . • • 375
Rocks, habitat of Lichens . . . 360
habitat of pleurococcufl • • •
Rod-shaped bacteria . . . 343
Romans, use of beans b\ . 317
Roots of ferns 369
of pine
Rose, a common plant family . 328
compound Leaves of .... 294
326
3-_'i ;
326
178
95
Rose, continui d
family, discussed ....
foods furnished by ... KM
Mow it t urning into a fruit I
leaf, stipule-, ,d (fig.) . .
stamens and pistil of <uj. I .
thorns of i fig.) , , .
Rosebreasted grosbeak, it
Buet station 1 1 ^
desl roj er of potato be<
Rosette of moss plant
Rotating crops, reason for
Rootcap (fig.)
Roothairs, of bean (fig.) .
uses of
Rootlets of bean
m1 two corn plant*, (fig.) .
Roots, of alfalfa (fig . •
of bean
of beet (fig.)
Of dahlia (fig.)
of eiiibr\ 0 301
of radish (fig.)
Rootstocks
Root system, of bean . .
of corn 280
Round clams 100
Round leaves of sundew .
Rudimentary toes of cow
Rules of hygiene 351
Rumen, division of stomach of
sheep (fig.) 154
Rushes related to ferns . .
Rye. a cereal (fig.)
a monocotj ledon
member ol grass familj
Rye bread, value of as f 1 178
Sage, a member ol mint family
Sage brush | ti-.i
Sailing birds, examples of .
wings of
Salamander, p|
discussed I ... n •
Saliva, us.- of, in man .
of mosquito
Salivary glands, of man.
t ion of
of mosquito
34
INDEX
References are to pages
Salmon, example of bony fish .
in hatcheries
landlocked, eggs of (fig.) . .
value of as food
Salt, a fundamental taste . .
common, scientific name of
use of in preserving meat . .
Salt rising bread
Salts in food
Salvia flower (fig.) ....
Sand swallow, nest of . . .
Sand worm
San Jose scale, an injurious
insect
Sap, flow of, in spring ....
Sap conducted laterally by
medullary rays ....
Sap tubes affected in bean
blight
Saprophytes, group of fungi .
Sardines, example of bony fish
Savory, member of. mint family
Sawdust, adulterant ....
Saw-fly, horn-tailed (fig.) . .
Scale insects, spray for . . .
Scale-like leaves of cedar
Scales, of fish (fig.)
modifications of skin . . .
Scales of staminate cone . .
Scallops, edible mollusks . .
Scarlet fever, probable cause of
Scars, characteristic of stem
Schiller on use of wine . .
Scholarship, effect of smoking
on
effect of drink on (fig.) . . .
Sclera
Sclerotic coat (fig.) ....
Scorpions, example of Arach-
nida
Scouring rush
Screech owl, a useful bird . .
adult (fig.)
at suet station
Scutellum, digestive organ of
corn grain .... 262, 266,
Scutes of snake
Scyphozoa, classified ....
Sea-anemone, described . . .
member of coelenterates . . .
106
111
110
178
165
173
347
179
173
306
142
84
24
291
291
315
354
106
331
180
40
25
383
107
190
379
100
234
286
220
229
221
215
216
91
374
145
138
148
280
131
6
68
63
Sea-cucumber, member of
coelenterates
Sea-fans, described
member of coelenterates . . .
Sea-lily, member of coelenter-
ates (fig.) 71
Sealing, object of
Sea-lions (fig.)
Sea-plumes, described . . .
Sea-turtle (fig.)
Sea-urchins, classified . . .
members of echinoderms (fig.) 71
Sea-weed, removal of from
oyster beds
Sea-worm a true worm . .
Secondary roots of bean . .
Secretions of sundew, use of
Sectional view of branch in-
fected with mistletoe (fig.) •
Section through scab of pear
(tig-)
Seed, development of ... .
distribution of
of pine (fig.)
of strawberry
Seed-bearing plants, a group
of plants
trees
Seed bud (plumule) ....
connection with seed leaves
Seed coat (testa)
Seed distribution
Seed-eating birds . . . 147,
bill of
claws of
Seed leaves, connection with
seed bud
Seedless plants, a group of
plants
Seedlings, honey locust (fig.) .
horsechestnut (fig.) ....
maple (figs.) ..... 279,
wheat (fig.)
Seed-producing organs of
pine
Seeds, of berries
changes in size made by cross
fertilization
devices for distributing . . .
food of birds
71
69
63
,74
347
153
69
129
6
,74
74
84
267
390
399
359
301
311
387
310
7
377
260
261
260
311
148
137
137
261
7
281
281
280
282
379
310
311
336
148
INDEX
R( u /■< noes
Seeds, continued
of cotton ( fig. | 313
of weeds
Selaginella (tig.) ;,7}
member of tern group .... 373
Selection, effect on wild plants 320
Self-heal (fig.) ;;;;;;
Self-pollination, discussed . . 306
prevention of 306
Semi-circular canals of ear . 218
Sensation, a life process ... 2
Sense organs, list of ... . _'ir.
of touch, locution of ... . 190
Senses, use of 2
Sensory function of afferent
nerves 213
Sepals, described 296
Sepia, described 100
Septic sore throat, epidemic <»f
(fig.) 243
Serrate edge of leaf of Rose
family 328
Seta of moss sporophyte . . 366
Setae of earthworm .... B0
Seventeen year locust (ci-
cada)
Severe cold, effect of on plants 396
Sewage, improper can- of . . 'JIT
Sexual reproduction ....
of hydra 66
of spirogyra 341
Sexual spore :;ii
Shad, example of bony tisli . . Hx;
raised in hatcheries . . . . Ill
Shaggy cap or cover of moss
capsule :^;i
Shape and size of bacteria 343
Sharks, a division of fishes , . 106
Sharp-shinned hawk, partly
harmful 146
Sheep, economic value of 154,166
example of mammal .... 7
fed on beans 316
stomach of (fig.) 164
Shell of slug 99
Shells of snail (liii) .... 99
Shrews destroyed by hawks l \:>
Shrike (great northern), a win-
ter visitant Ill
loggerhead (tig.) 139
ill'i tO /nil/' s
Shrimp.s, economic Importai
of
Sickness, student report on .
Sieve vessels of phlotfm
use <d
Silica in skeleton of sponge 61
Silique of mustard ly
(fruit i
Silk of corn, attachment of
t he Btyle
Silkworm, a beneficial insect .
Simple leaf (fig.)
of beech family
defined
Sinus, defined
Siphonaptera, an order ol ln«
sects 20
Siphons of clams Mi_. i . .
Siphons of soft-shell- rn
(fig.) 100
Skating, good exercise . . .
Skeletal structures, student
report on 187
Skeleton, external, of corals
of crayfish
of dog (fig.) ;
of fish (fig.) I
of leal (fig.)
Of mallard duck (fig | . . . .
Of man (fig.) 184
summary ol .... r«>
of protozos
of sponges (fig.) . . • "■'•. 'd
Skill and endurance ii: >d
by drink (fig.)
Skin, as sense organ ...
described . 216
diagram of (fig.)
example i in
of fruit
Skunk, example of harmful
mammal ( ti^.i . .
Sleep, amount needed . .
Sleeping sickness how »pn id
probable cause of . . .
Slimy feeling of spirot •
Slimy substunc. | ipoo
r< nio\ ed h\ b
Blips producing
roots '"1
36
INDEX
References are to pages
Slug- (garden)
Slugs, examples of mollusks
Small cells, position of in annual
99
94
290
116
168
251
250
234
14
Small intestine, of frog . . .
of man
Smallpox, Jenner and ....
lessened by vaccination . . .
probable cause of
Smell, organ of, in grasshopper
Smoke, result of chemical
change 9
of puffball 364
Smoker's heart, how affected . 227
Smoking, charts showing effect
of 228, 229
Smoking and scholarship . . 229
Smoking of meat, purpose of . 347
Snails, discussed 98
example of Gastropoda (fig.) 6, 98
examples of mollusks . . . . 6, 94
respiration in 99
shells (fig.) 99
tongue of (fig.) 98
Snakes, (black,) harmful . . . 132
discussed 131
examples of Reptilia ... 7, 129
food of 132
Sneezing, distribution of germs
by 197
Snowy owl a winter visi-
tant 141
Soda, a nutrient 176
preservative 348
Sodium carbonate in artifi-
cial pancreatic juice . . 173
Sodium chloride, scientific
name for common salt . . . 173
Soft palate of man .... 166
Soft-shelled clam, an edible
mollusk (fig.) 100
discussed 100
Soft-shelled crab (fig.) ... 91
Soil, an element of success in
agriculture 320
upper layers, habitat of bacteria 344
Soil bacteria (fig.) ...... 344
Soldiers, a class of ants ... 41
Soles of feet, animals that walk
on 152
Solomon's seal, stems of . . 285
Song sparrow, at hemp and
millet station 148
killed by hawks 145
useful bird 144
Sori, of ferns (figs.) . . . .370,371
Sorus, position of (fig.) . . . 372
section of (fig.) 372
Sounds from sound waves . 218
Sour, a fundamental taste . . 165
Source of man's food sup-
ply 320
Sources of danger in milk . 349
Souring of milk, cause of . 348, 350
Sparrow, chipping, useful bird 144
English, chatter attracts other
birds 148
example of bird 7
fox, example of transient bird 141
hawk, destroyer of grass-
hoppers 22
destroyer of cicadas ... 26
Sparrows, seed-eaters .... 148
Spawn, migrations of fishes to 109
Spearmint, member of mint
family 331
Special modifications of
plants 389
Special senses, organs of . . 215
Species defined by Linnaeus 303
Specific names used by Lin-
naeus 303
Sperm, a sexual cell 4
cells of fern 371
of moss plant 365
volvox 56
nucleus of pollen grains . . . 299
Spermaries of hydroids . . 68
Sphinx moth from tomato
worm ........ 34
Spicules, described (fig.) ... 59
Spider, member of Arachnida
(fig.) 91,92
Spinal column of man, curves
of 187
Spinal cord, part of nervous
system 119
Spines of echinoderms ... 71
Spiracles, location of ... . 16
of grasshopper ...... 15
/ \ DEX
Spiral arrangement of scales
on cones 379
Spiral bands of chlorophyll
in spirogyra 310
Spirillum, a form of bacterium 343
Spirogyra, example of algae 7.
conjugating (fig.) 340
described 339
microphotograph of (fig.) . . 341
Spirog-yra and pleurococcus,
summary of 342
Sponges, bath (fig.) .... 58
classified 6
clog water mains (>1
described .".7
economic importance of . . . r,i
example of Porifera .... »i
how gathered 61
how prepared 61
number of 6
parts of (fig.) 59
relation to other animals . . til
reproduction <K>
structure of 58
summary of 62
two stages in development of
(fig.) 60
use of bacteria in preparation of .'^.".
where obtained <>1
Spongilla, reproduction of . . 60
Spongy layer of leaf .... 27:;
tissue of velamens 399
Spleen, of frog 117
Splints, used in Betting bones 186
Spoiling of food by bacteria . 347
Sporangia, of pteris (fig.) . . .".71
Sporangium, of club moss (fig.) 373
Spores (tig.) 360
of bread mold 357
of (dub moss ( fig. ) 373
of corn smut (fig.) 362
of moss 364
Sporophyte, dependence of . . 366
generation of moss 366
Sprain, defined 186
Spraying solution, ingredients
of 25
outfit (fig.) 21
Sprouting of grain to furnish
malt 355
an to i ""/>'*
Spruce, compared with pine
• cample ol l:> mnosperm
t iii'- source "i vrood pulp
wood of (fig.)
Sputum, destructi 1 m
<\\
Bpread of t uberculo«
Squarr -I'msof mint family
Squash, a dicotyledon . . .
example ol j »* - j *• •
d (fig.)
Squid, described
example of ( lepbalopoda
of niullnsk
Squirrel, agents in plant dis-
persal
flying (fig.)
gray (fig.)
Stagnant pool, breeding place
for mosquitoes
Stalk of grain of corn . . .
Stamen, diagram of . . . .
Stamens and pistils of |
(fig.)
Staminate cones of pine . .
Staminate flower
of monoecious plants ....
Ol willow ( tiur- )
Staminate strobili. ol pirn 77
Starch, a nutrient
chemical composition of ■
form of carbohydrate ....
in fermentation . . .
in floor
product "f photosj ni bests
Starfish, anatomj ol (fig. I
body "t". diagram ....
classified
described (fig.) • •
familj
group
internal struct are of
life bistorj of ...
looomol ion of . . . .
•-n miliary of ...
State governments, pi
tion ni fires bj
Statistics of life Insurance
companies . .
Steam, a form of water
i
311
152
151
11
1
17''
71
71
71
38
INDEX
References are to pages
Steam heating (fig.) . . 195, 197
Steering", use of fins for . . . 107
Stegomyia, a mosquito ... 42
Stem, of bean 260
of corn (fig.) 280
of ferns 369
of mosses 364
of pteris (fig.) .... 369, 370
of xerophytes, green color of . 396
woody (fig.) 289
Sterile, defined 347
Sterile hairs, of moss plants . 365
Sterilized -water in tests for
bacteria 347
Sternum, keeled, of birds . . 138
Sticklebacks, nests of ... . 112
Stigma, part of pistil .... 297
featbery 305
Stimulant, craving for ... 226
Stimuli, causing movement . . 392
list of 2
Stinging- cells of coelenterates 64
Sting of bee .' . 36
Stipe, of fern 373
Stipules, of pulse family . . . 329
of rose leaf (fig.) 331
Stomach, a digestive organ . . 2
example of organ 5
microphotograpb of ... . 170
of sbeep (fig.) 154
of starfish, use of in food-
taking 73
pear-sbaped (fig.) 168
valves of 168
Stomach-intestine of earth-
worm 81
Stomata, entrance of bacteria
tbrougb 315
number of 274
in xeropbytes 396
of fern 373
of leaf 273
position of in waterlilies . 274, 394
size of 274
Stonefhes, members of Plecop-
tera 20
Stone fruits, defined .... 310
Stone of drupe 310
Stones, inorganic matter ... 10
wet by spray habitat of mosses 364
Storage of food in leaves . . 293
Straight-veined leaves of
beech family 327
Stramonium, a medicine, source
of 331
Strawberry, description of . . 310
produced by rose family . . . 329
value of as food 178
Street cleaning by flushing,
advantage of 235
String beans, canning of . . . 317
ovules in 309
value of as food 317
Strobili, of pine 379
staminate (fig.) 377
Structural changes due to
alcohol 225
Structure of amoeba .... 47
of paramoeciurn 50
of roots 267
of woody stems 287
Struggle for existence, dis-
cussed 314
modifications aiding in . . . 389
Student report, on sickness . 232
on skeletal structures . . . 187
on water supply 242
Studies about plants, kinds
of 311
Study of lichens, field trip for 362
Study of plants as organisms . 320
Style, part of pistil 297
Success in cultivating plants 320
Sucking disks of starfish . . 73
Suction in photosynthesis . 276
Suet, for winter feeding of birds 148
station 148
Suet-eating birds 148
Suffocation discussed . . . 196
Sugar, a nutrient 1
broken up by yeast enzyme . 354
elements in 9
form of carbohydrate .... 265
in flour 179
obtained from maple trees . . 385
organic matter 10
product of photosynthesis . . 276
solution in study of spirogyra 341
source of 400
value of as food 178
INDEX
Re/i n in-' $
Sugars formed in fermenta-
tion 365
Sulphur, a disinfectant . . . 253
an elemenl in living things . . 9
in spraying solul Ion .... 25
Summary, of amphibians . . 127
arthropods 93
bacteria ."..".1
bean 320
birds 149
circulation jus
con iters 388
corn 321
digestion of man l*'j
disease 258
ferns and their allies .... 375
fish 112
flowering plants 336
fungi :;•;_'
hydra-like animals 7<»
insects 4.1
mammals 159
mollusks KL'
mosses and their allies . . . 368
nervous system '_':!<>
of our interest in plants . . . 40i
protozoa 54
reptiles 135
simplest plants 339
skeleton of man l'.»<>
spirogyra and pleurococcus . 342
sponges 62
starfish group 75
worm group 84
Summer residents, examples
of ill
Sundew, described 390
diagram of (rig.) ."-'.'1
photograph of (tig.) .... 390
rapid movements of . • . . 392
sticky substance on leaves . 390
use of leaves in 294
Sunflsh, care of eggs by . . . 112
example of bony tish (fig.) 104, 106
Sunflower, " seed " (I'm. ) . . 262
stem, microphotograpb of i fig.) 286
Superficial lymphatics of
arm and hand (tie,.) . ■ . 204
Supply of oxygen kept up
by plants I'd
t<> pagy
' Surplus food stored in ro>
' Survival of the fitter
Swallows, destroj
insects
Swallow-tail b>. pol-
linating Persian til
from celerj \\ orms
la rvaa of
Swamp, breeding place for i
quitoes (fig.)
Swarming of bees ....
Sweat glands, location of . ,
number of
work of
Sweet, a fundamental taste . .
Sweet pea. flower of (1
Swifts, destroyers of flying bi-
sects
Symbiosis, a dependent relation
defined
example of
Symptoms, medicines in con-
ned ion with
314
190
165
i «
361
61
245
Tachina fly. beneficial Insect
Tadpole, development of from
two stages in (fig.) ....
respiration of by gills ....
Btage of frog
Tail region of flsh
Talons, characteristic <»f birds
of prey
Tanning, use of hemlock hark in
Tap root of bean
Tapeworm, a common (fig.)
classified
Tar. source of
Tarsus of grasshopper's foot
Tartar, effect on gums ....
Tassel, staminate flower ol corn
Taste cells (fig.)
Technical names of of
flower
Teeth, milk (fig.) • •
ol man
permanent (fig.)
Telegraph poles, use of gyTOr
oosperms for
n
122
122
106
in
78
<■
16
167
166
II I
167
•N|
40
INDEX
References are to pages
Temperament, excitable, heart
tracings of (fig.) 228
phlegmatic, heart tracings of
(fig.) 228
Temperate regions as a
habitat 161
of evergreens 381
Temperature
of birds 138
offish 109
of soil, an element of success
in agriculture 320
Tendrils of pea plant (fig.) . . 291
response of to contact . . . 393
Tent caterpillar 28
Tentacles of hydra .... 64
Terminal bud 288
cones in relation to .... 379
Terrapin, use of as food . . . 131
Testa developed from in-
tegument 301
Test for oxygen 8
Test for weevils 316
Tests for foodstuffs 265
in baking and brewing . . . 356
Thalamencephalon of frog . 120
Thalessa, larva of 40
Thallophytes, classified ... 7
Thallus of marchantia . . . 367
Thick stems for food stor-
age 285
Thick- -walled cells of annual
ring, how formed .... 290
Thigmotropism, defined . . 284
in climbing plants 287
in roots 284
Thin- walled cells, when
formed 377
Thirty years of diphtheria in
N. Y. State (fig.) .... 242
Thistle, a common weed . . . 334
Thoracic cavity 201
Thoracic duct 174
Thorax, of grasshopper ... 13
Thorn, modified leaf (fig.) . . 293
Thorns of rose (fig.) .... 329
Thousand-legged worms
(fig.) 92, 93
Thread-like hairs, of spirilla
and bacilli 343
Threads, of bread mold ... 357
of spirogyra . . . * . . . . 340
Throat, cavity of man . . 164, 166
of tadpole 122
Thyme, a member of mint
family 331
16
43
91
155
30
153
263
331
34
Tibia, of grasshopper . . .
Ticks, harmful insects . . .
members of Araehnida . .
Tigers, harmful animals . .
Timbers of mines, use of gym-
nosperms for 384
Tissue 4, 5
definition of 268
Toad, horned (fig.) 129
Toads, hibernation of .... 123
Toadstools, example of fungi . 7
Tobacco, aroma of, produced
by bacteria 345
effects of use of 226
inhaling fumes 229
member of nightshade family . 331
Tobacco worm, bearing co-
coons of parasite (fig) . . .
Toes of cow, rudimentary . .
Tomato, a dicotyledon . . .
food plant of nightshade family
worms, larvae of sphinx moth ,
Tongue, a sense organ (fig.) 165, 215
of man 164
of snail (fig.) 98
Toothache, result of poor teeth 167
Tortoise, use of as food ... 131
Touch, movement caused by . 392
skin, an organ of 215
Toxin, bacterial poison . . . 351
of diphtheria 252
secreted by bacteria .... 345
Trachea, of man 192
of grasshopper 15
Trailing arbutus, creeping
stem of (fig.)
Transformation of pupa of
mourning cloak butterfly
into adult (fig.) ....
Transient birds, examples of
Transpiration, defined . .
devices for retarding . . .
experiment to show . . .
in full grown leaves . . .
288
29
141
274
397
295
291
INDEX
11
Trap-like device of Venus's
fly-trap 39]
Tree cricket, incomplete meta-
morphosis <>| (fig.) ... 17
harm !ul insect 22
Tree frog (fig.) 126
Tree killed by bracket fun-
gus (fig.) 369
Tree sparrow at bread crumb
station Ms
at suet station Ms
Trees, habitat of lichens . . . 360
life processes of 259
Tremex borer, harmful insect • 40
Triangular flaps, mouth of
clam «x;
Trichina, discussed 77
Trichinella, discussed (fig.) . 77. 7^
Trichinosis, cause of ... . 7H
Trichocysts of paramoecium 60
Tropical vegetation (fig.) . . 4< >1
Tropics, as a habitat .... 161
home of epiphytes 399
Trout, example of fish .... »i
bony fish 106
True flowering plants . . . 323
Trunk region of flsh . . . . l<x;
Trunks of evergreens . . . :;77
Tsetse fly, sleeping sickness
spread by 239
Tubercles, on roots of bean
family 270
Tuberculin test, for cows . . 349
invented by Koch 361
Tuberculosis, a bacterial dis-
ease 197
cure, summer (fig.) .... 236
winter (fig.) 237
discussed 236
in cows 349
of throat and other organs . . 237
persons affected 240
Tubular appendages of male
crayfish ^7
Tubules, of kidney 207
Turgid cells J7.">
Turnip, member of mustard
family
storage of food in 283
Value of as food 178
an to /""/' s
Turpentine, source of ... .
Turtle, example ol Reptllia 7. 129
green, use of as 1 1 . 13]
skeleton of 190
Turtles, discussed 130
Twining petiole, of clemal
(fig.) . . ...
Ol nast urt mm (fig.) .
Twining plants, direction of
curve of
Twining stem of dodder
(fig.)
Twining stems
Two-parted flower of mint
(fig.)
Tympanic cavity
Tympanic membrane . .
Types, of mosses I fig. I . .
of twigs (fig.)
Typhoid fever, a bacterial <li:
ease
spread by carriers
Typical fern, pteris ....
Typical flowering plant, bean
a
U
Ulmus americana 7
Umbel
Umbrella-shaped branches
of marchantia
Underground stems, de-crih.. I
examples ol
of pteris
Undissolved food 17}
Unhealthy cows, milk tr.'in
Unicellular fundus. yeasl an
example
Univalves
Universal stimuli of plants
Unusual plants
Unwashed hands, number <>f
bacteria on
Ureter, of frog 1 17
ol man 2tfi
Urethra, of man
Urine, defined • 308
Urinary bladder of frog 117
Useful birds. .\. in.. Ml
42
INDEX
References are to pages
Vaccination, discussed . . .
Vacuole, food, of amoeba . .
contractile
Vacuoles, in nerve cells . . .
Valves of arteries and veins . .
of stomach
Vapor, a form of water . . .
Variations in legs of birds .
Varied diet of man ....
Various forms of cells in
human body (fig.) . . .
Vascular bundles, formation
of tubes by
of root
of woody stems
Vascular system in plants . .
Vase-like leaves of pitcher
plant
Vaseline, use of in transpira-
tion experiment
Vase-shaped organs (arche-
gonia) of moss
Vedalia, beneficial beetle . .
Vegetable food, highest form
of
Vegetable forms of protein
cheaper than meat . . .
Vegetable nitrogen, source of
Vegetables, new varieties pro-
duced by cross-pollination .
food of man
Veins, compared with fibro-
vascular bundles ....
diagram of (fig.)
of leaf 268,
of man
of the leaf of pteris (fig.) . .
of wing of insect
Velamens
Ventilation
room at night, direct heating
(fig.)
indirect heating (fig.) . . .
room in daytime, direct heat-
ing (fig.)
indirect heating (fig.) • . •
Ventral blood vessel of earth-
worm
250
48
49
225
202
168
9
136
170
189
268
268
287
278
389
275
365
27
311
317
400
306
2
268
201
272
197
371
29
399
195
197
196
197
196
82
Ventral nerve chain of cray-
fish 90
Ventral surface of earthworm 80
Ventricle (fourth) of brain . . 119
Ventricles of heart . . . . 201
Venus mercenaria, edible mol-
lusk 100
Venus's flytrap (fig.) .... 391
rapid movement of .... 392
use of leaves in 294
Vermiform appendix . . . 168
Vertebrates, a group of ani-
mals 6
discussed 103
Vesper sparrow, at hemp and
millet station 148
Vetch, member of pulse family 329
Villi, described .173
Villus, diagram of (fig.) . . . 174
Vines, comparison with tree
trunks .... ... 286
Violet, capsule of (fig.) . 308, 310
cleistogamous flower of . . . 302
example of irregular flower . 302
fruit of (fig.) ....... 308
long-spurred (fig.) ..... 397
plant (fig.) 301
Virginia deer (fig.) .... 156
fawns of (fig.) 156
Virgin forest (fig.) 379
Virus in inoculation .... 252
Viscera of clam 98
Visceral ganglion of clam . 98
Vitreous humor 216
Vocal cords, location of . . . 194
Voice box (fig.) .... 193, 194
Voluntary muscle cells (fig.) 188
Voluntary muscles .... 188
Volvox 55
colonial protozoa, example of . 55
described (fig.) 56
Vomiting 168
Vorticella (fig.) 52
Vultures, beneficial birds . . 147
example of Raptores .... 141
toe of 140
W
Walking sticks 20
Walnut, family discussed , . 327
I \ hi \
i.;
Walnut, continut d
plant protein in English • . . IT"
tree (fig.)
twig (fig.)
Warbler, yellow, nest <»f (fig.). 142
Warm-blooded animals . . IfiO
Warm milk, moltiplicatioo <»f
bacteria in 360
Warmth. ;i condition of the
growth of bacteria 34 1
Washing away of soil by
floods 386
Wasp fly, beneficial insert . . n
Wasps, members of Bymenop-
tera 20
Waste land, after a fire I figs. I . 381
Waste materials of photosyn-
thesis; 276
Waste products of IkmIv . . 206
removed by excretion . . . 2<n;
Water, a necessary condition for
growth of bacteria .... 347
basis of classifying plants in
societies 393
contains bacteria •"•h
composition of 9
habitat of plants 323
sanitary measures forprotecting 242
supply, stti'lent report on . . 242
Water beetles, destroyers of
mosquitoes 42
Water horehound (fig.) . . 331
Waterlilies, air supply of . . •".'.»»
hydrophytes (fig.)
structure of stem of . . . . 286
white (fig.) 392
Water snail, host of liver fluke 77
Wax, in ear 218
produced in U. 8., value of . 39
Waxed paper, in transpira-
tion experiment 296
Weasels, destroyed by hawks . i \'<
harmful animals 1 56
Webbed toes, of Bwimming
birds i '~
Weeds, common, lisi of . . .
definition of
in plant succession 400
reasons for success of .
seeds destroyed by birds . . . M7
at
140
148
108
216
'//•■ to i ■
Weevils, damage to beam
(fig.) • ■
harmful beetles
Wheat, ■ monocotyledoi
amount produced i>\ i S. . .
bread, \ aloe of ai foiMi . . . ] 7 ^
breakfasl food, value 0 i 178
cereal (fig.)
flour, value of as fo< ■•! ...
Indehiscenl fruit
map «>f production >>t < I
member of grass family .
one of first cultivated plant s
• dlings 1 iiu )
Whip grafting- Mi _- 1 . .
White blood corpu.-rles
White-breasted nuth.
u hole -rain stat iou ,
White-crowned sparrow
bemp ami millet stat ion
Whiteflsh, example of a bony
fish
White grubs eaten by birds
White of the eye
White pine, value of ... .
White-throated sparrow
hemp and millet station . . n>
Whole grain station, bir.ls
frequent ing 149
Whooping cough, a bacterial
rtifleanfi
e\posUle t0
Wigglers. larva- of mosquito*-* 19
Wild plants, Improvement of by
man
Willow, flow . -"l
Wind-distributed frn."
Window-growing plant
sponse to light in ...
Windpipe ....
Wind-pollinated I rfl of
grass Family . .
characterist ica of
id pollination
Wine, use of yeast in making
Wing-Wee air sues of pine
pollen
Wing of pine seed
Wings, ol birds ....
Is ^''
44
INDEX
References are to pages
Winter visitants, examples of 141
Wistaria, member of the pulse
family 329
Witch-hazel, explosive fruit of 312
Wood, example of organic mat-
ter 10
formation of 290
of spruce (fig.) 290
sections of (fig.) 290
Woodchucks, young (fig) • • 157
Wooded area, under govern-
ment control 387
Woodpeckers, at suet station 148
(downy) permanent residents . 141
food of 27, 31
holes made by (fig.) .... 27
Wood-pulp, source of ... . 384
Woody stem, sections of (fig.) 289
structure of 287
use of elements in 290
Woody twig, buds of ... . 287
Wool, source of 155
indirect product of plants . . 401
Woolly aphis, member of He-
miptera (fig.) 24, 25
Work, of the yeast plant . . . 354
of bean leaf 275
Workers (bees) 35
Worm, in the apple (fig.) ... 18
planarian (fig.) 77
Worm-like animals, classified 6
Worm group, discussed ... 76
summary of 84
Worms, classified 6
Wort, formation of 355
Wren, a useful bird 145
food of 31
X-ray photograph, of appen-
dix and part of large intes-
tine (fig.) . 169
of Easter lily (fig.) .... 327
of elbow (fig.) 185
of hand of adult (fig.) .... 186
of child (fig.) 186
of human stomach (fig.) . . . 168
Xylem, conductor of water . . 290
in fibrovascular bundle of corn 280
position in vascular bundle . . 269
relation to cambium .... 287
Xerophytes
396
Year's growth of twig, how
told 289
Yeast, in bread making . . ' . 179
plant, described (fig.) . . . 354, 355
enzyme of 354
use of 355
reproduction of 3
Yellow fever, carried by mos-
quito 42, 239
caused by protozoa . . .47, 234
Yellow pine, value of ... . 385
Yellow swallowtail (fig.) . . 33
Yellow warbler, nest of (fig.) . 142
Yolk, of fish eggs 109
sac on young fish (fig.) • • . HI
Youth, a period of life .... 163
Zeppelins, use of hydrogen gas
for 8
Zygospore, advantages of . . 341
Zygote of spirogyra .... 341
Zymase, work of 179
IMPORT U8HARY
% C State CWIejfe
Live Music Archive
Librivox Free Audio
Metropolitan Museum
Cleveland Museum of Art
Internet Arcade
Console Living Room
Books to Borrow
Open Library
TV News
Understanding 9/11