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Notijjooli UJregg 

J. S. Cushing Co. — Berwick & Smith Co. 

Norwood, Mass., U.S.A. 



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 



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. 


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, 

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. 



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. 




Introduction 1 


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 



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 







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 



Elms at the Water's Brink Frontispiece 


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 




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 



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 



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 




Leaving Its Nest 


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 







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 .... 




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 


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 











































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 


Two-Parted Flower of Mint 

Lady Slipper 

Flower of Columbine .... 


Easter Lily ...... 

Fruit of the Bean .... 

Fruit of the Corn 
Fruit of the Poppy 
Capsule of Violet 
Chestnuts . 

324. Dry Fruits 

















































Vertical Section of Apple . 


Cross Section of Apple 


Cross Section of Orange 


Forms of Dehiscent Fruits 


Fruits with Hooks 


Burdock in Blossom . 


Fruits Distributed by Wind 


Other Fruits Distributed by Wind 


Fruits and Seeds 


Milkweed Plant .... 


Seed of Cotton .... 


Bean Plant Injured by Bacteria . 


Beans Damaged by Weevils 


A Field of Beans 




Map of Corn Production 


Walnut Tree 


Map of Production of Oats 


Map of Wheat Production 


The Cereals 




X-Ray of Easter Lily . 


Leaves and Bud of Beech 


Wild Columbine . 


Stamens and Pistils of Rose 


Rose Flower Turning into a Fruit 


Thorns of Rose .... 


Map of Production of Orchard Fruits 


Stipules of Rose Leaf . 


Flower of Mallow 


Water Horehound 


Map of Cotton Production . 


Self-Heal . 


Hedge Nettle 


Common White Daisy 


Dandelion . 


Map of Potato Production 


Canada Thistle . 




Spirogyra . 


Spirogyra Conjugating 

366. Microphotograph of Conjugating Spirogyra 















































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 . 
















































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 




Agassi z 
Koch . 

IM IM. v \..r 

. 30 

. 100 

. 170 

. 235 

. 303 

. 348 



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 functions 1 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 > ' ant MMMMH7 f Bwn 

1 * C State Oik* 


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 

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 


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 

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. 


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 

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. 


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. 


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 


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. 


2. Amphibia. Example, frog, salamander. 14,000 different kinds. 

3. Reptilia. Example, snakes, turtles, alligators. 35,000 different 


4. Birds. Example, sparrow, eagle, hawk, crow. 13,000 different 


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 


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 





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 

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. 


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 


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. 






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, 


Figure 6. — Female 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. 


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 : 





Mouth Parts 

Where Found 

a x 

- 5 


— f. 

- C 
~. Z. 

Size oi 

Size oi 





House fly . 

On food in the home 




On grass in the field 




Moth . . 

On flowers in the park 






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. 


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- 




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 









'.;) 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 


maxi ila 


a bium 

Figure 8. — Mouth Parts of the 



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 

Figure 9. 

a, Grasshopper laying Eggs ; b. Egg- 
capsule ; c, Eggs. 



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- 



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. 



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 

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 



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 


1 Sometimes the codling moth passes into the pupa stage in the fall, 
thus living through the winter in the " resting stage." 



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 

The grasshopper belongs to 
the order known as Orthop- 
tera 1 (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 

1 grasshoppers, katydids, crickets 
butterflies and motbs 

bees, wasps, ichneumons, gall flies 
flies and mosquitoes 
dragon flies 
May flies 
stone flies 

(straight wings) 
(scaly wings) 
(shield wings) 
(half wings) 
(membrane wings) 
(two wings) 
(short lived) 
(net wings) 

often called siphon-mouthed 














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. 


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 

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 

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 


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. 


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 ? 




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 




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 



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 

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 

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. 



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. 
Being 1 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- 



Figure 23. 

-Redheaded Wood- 

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- 



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. 



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. 



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 

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 

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. 



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. 



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. 



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. 


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 larva 1 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. 





Spun with 
silk only 

Spun with 
a leaf 

Spun with 


from one end 

from one loop 


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 



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. 



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. 



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 

Figure 36. — Honey Bees Clustering 
at Swarming Time. 



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. 



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 



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. 



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. 



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. 






- * ' 

' ■!, 


if ft 


3 ; - - 

Figure 43. — Eggs and Larwe of 


The commonest mosquito. 

or seashore during the 
summer. (2) Anopheles 
(a-nof 7 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 


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. 


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 


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. 


Explain the difference between beneficial and injurious insects. 
Which are some of our most beneficial insects ? How do they help 

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 ? 


Crary, Field Zoology, Chapter X. 

Folsom, Entomology with Reference to Its Biological and Economic 

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. 



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, 



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, 



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 

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 


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 

There is no well- 
defined cell wall ; there- 

Feelmg pseudopodium. 
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 


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, 

When the food or water be- 
comes unsuited to supply the _ A m 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. 



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.) 


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 







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 



Figure 48. — Diagram of Paramcecium. 



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. 





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- 

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. 


i ! S'.-.«. J i\:-i.v.' 

Figure 52. — One of the 

Figure 53. — Some Flagellate 

each with certain distinct characteristics. For instance, all 
Protozoa that have pseudopodia are called Rhizopoda. In 



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. 


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. 


How Many Kinds — 

How Many Kind> 
Have — 


are free 
swimming ? 

are attached 
by threads? 

have even 
motion ': 

have zigzag 
motion ? 

form ': 

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. 



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. 


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 ? 


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. 



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- 

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 


Figure 54. — Gonium. 






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. 


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 

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 



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. 



& 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. 


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 



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. 


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). 



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. 


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 ? 


Hegner, Introduction to Zoology, Chapter VI. 
Jordan and Kellogg, Animal Life, Chapter II. 
Osborne, Economic Zoology, Chapter III. 



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. 




Figure 61. — Diagram of Body 
of Hydra. 

gloios, glutinous substance) ; 
and the inner layer, endo- 

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. 



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 




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 

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. 



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. 


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 


Figure 65. — Diagram of the 
Hydroid Bougainvillea. 



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 

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 

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 



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.) 



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 

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. 


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. 


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. 


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. 


Darwin, Structure and Distribution of Coral Reefs. 
Hegner, Introduction to Zoology, Chapter VIII. 



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 


Figure 71. — Starfish. 



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 


Tfu 1 

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 


Figure 73. — Anatomy of the Starfish, glands, which vary in 


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. 


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. 



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. 


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. 


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. 


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 ? 


Brooks, The Oyster. 

Osborne, Economic Zoology, Chapter VIII. 

Poulton, All About the Oyster. 




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 

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. 


® : 









narian Worm. 


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 

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. 




■ ■■ 

esMIh M?^ va a ■■■■ 

'•' . 1§ v i\*f '^^f if) , 

Figure 77. — Trichi- 


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 


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. 


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 


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 


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. 


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 8 o.- Diagram. 

as the body cavity or T h e 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 tw r o thirds of the 
length of the worm. 



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- 

Front end of nervous 


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. 


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. 



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. 


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 


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. 


"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. 


Darwin, Earthworms and Vegetable Mould. 

Jordan, Kellogg, and Heath, Animal Studies, Chapter VI. 

Sedgwick and Wilson, General Biology. 



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 

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 


Figure 83. — Crayfish 
bearing Eggs. 



are clearly defined, but 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 

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. 



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). 


Place several crayfish in jars or aquaria and observe their behavior. 
Fill out the following report : 


Move the 


Forward ? 



Backward ? 

Do they Use 
Caudal Fin ? 


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. 



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. 


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 



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 

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- 



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 


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. 


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. 


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 ? 

See Chapter II. 



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, 


Figure 93. — Clam Showing Foot. 

Water enters through i.s., inhalent siphon, 
and leaves the body of the clam 
through e.s., exhalent siphon. 



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 


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. 


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 


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). 

- . " 





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 FlGUR o F 96 ^ 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 


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. 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. 




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- 

A common squid, Figure 100. — An Octopus. 



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 

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. 



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. 



have such natural enemies as the starfish removed, and, in 
the case of oysters, brush and shells are added that they 




w Vi? ■ 







\ 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. 


is one reason for the laws regulating the disposal of sewage, 
and for government inspection of the feeding grounds. 


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. 


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 ? 


Brooks, The Oyster. 
Cambridge Natural History, Vol. III. 
Kellogg, The Shellfish Industries. 
Linville and Kelly, Zoology. 



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 




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. 


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/ ' 

■ *^^ 






"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- 


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 


'2~-T~~* i 'm w 

^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 



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.) 


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 of 



Number of 


Which \i:k I -i D i" 

I><> the 

of Fins 

Advance ? 

Stop ? 

Balance f 

\'.\ bsMovi ! 


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 

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 


rakers or strainers and accordingly their gill rakers are 

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 


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} r s 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, 



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 


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 

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; 


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 

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 u beds." 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. 


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. 


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 ? 


Fish Manuals of the U. S. Commission of Fish and Fisheries. 

Jordan, Fishes. 

Jordan and Evermann, American Food and Game Fishes. 



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- 
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- 


Place one or two frogs or toads in a small jar or box and observe the 
points mentioned in the report below. 



Can tiiky 


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 


Uatoh \ Y\.\ :• 




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. 


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 


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 



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 




• 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 







nerve to nose 
Olfactory Lobe 

- Cerebrum 




Medulla ■-•- 


Optic Lobe 


"--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 

to leg 


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 


cord (Figure 117). In a long salamander there are 20 or 
30 pairs of nerves on the spinal cord. 


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 

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 



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 



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 

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 



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 



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 


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 

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 



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. 


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 

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. 


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. 


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 ? 


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 ? 


Dickerson, The Frog Book. 
Hodge, Nature Study and Life. 
Holmes, Biology of the Frog. 
Marshall, The Frog. 
Morgan, Embryology of the Frog. 



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. 




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, 



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- 

sometimes as much as a 
thousand pounds. The 
flesh of the green turtle 
and of the terrapin 
(ter'ra-pin) is used for 

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. 


young. Since snakes eat insects, frogs, mice, rats, and 
rabbits, they should be considered beneficial. 

Rattlesnakes 1 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). 



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. 



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. 




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. 


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 ? 


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? 


Ditmars, The Reptile Book. 
Jordan, Kellogg and Heath, Animal Studies. 
Linville and Kelly, General Zoology. 
Reese, The Alligator and its Allies. 



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 


Figure 136. — Grebe. 



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. 



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- 

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. 



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 



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. 



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. 



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 



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 



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. 



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 



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 



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 

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. 



— -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. 


is used : Blue jay, crow, white-breasted nuthatch, chickadee, 
quail, grouse. 1 


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. 


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. 


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 ? 


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, 



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 

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 

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- 




Figure 160. — Gray Squirrel. 

Figure 161. — Young Gray Squirrel 
LeavIng its Nest. 

Figure 162. — Young Foxes. 

Figure 163. — Bat Hibernating. 



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 



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 

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. 



Stomach of Sheep 






Figure 168. — Stomach of Sheep. 

Sheep, deer, and cows chew the "cud" 
and all have stomachs of several 

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. 


1 .").") 

Report on Mammals to be filled out first from general knowledge, later 
extended by trips to fields, woods, or parks. 



I'< >OD 

Kind of 

I. Ill IS 


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 

Figure 171. — Elk. 



Figure 172. — Virginia Deer. 

Figure 173. — Fawns of the Virginia Deer. 



Figure 174. — Coon. 

Figure 175. — Young Woodchucks. 



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 



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! 


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 


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 ? 


Davenport, Domestic Animals and Plants. 
Linville and Kelly, Zoology. 
Plumb, Types and Breeds of Farm Animals. 
Stone and Crane, American Animals. 





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. 




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. 


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. 







































































Earthworm .... 

Grasshopper .... 


English Sparrow . . 





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 

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 

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, 



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. 


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. 






One Cell 

Man y 






No Well 





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 







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 





Figure 179. — Alimentary 
Canal of Man. 

I l 

Figure 180. — Tongue. 

Figure 181. — Taste Cells. 

The taste nerve ends among 
these cells. 



nerves. In the brain the food stimulus is interpreted as 
sweet, sour, or bitter (Figure 181). 


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. 



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. 



Figure 184. — Pear- 
shaped Human 

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- p ot t e r. 

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. 



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 



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 




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. 




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 ? 







Minute plants . . 

Minute animals 


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 



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. 

Where the Food is Digested 

In the 

In the 








Paramecium . 

Hydra . . . 

Frog .... 

Man, etc. . . 

Bean .... 

Yeast .... 

Teacher may explain yeast and bean to help out the comparison. 


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. 


Study food and food tests. Artificial gastric juice is easily prepared 
"by taking | gram of pepsin, T a ff 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- 



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 



lph or 




back into sugar, which re- 
sults in keeping a uniform 
amount of sugar in the 

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. 



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. 


Figure 190. — Home-made Apparatus 
to show Osmosis. 

Food as 

Edible portion 

e.g., flesh of meat, yolk and 
white of eggs, wheat, flour, etc 




( Sarbohydrafe 9. 

Mineral mat; 

e.g., bones, entrails, shells, brain, etc. 


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 


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 bone r 

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 


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 

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 

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 



Comparative Cost of Digestible Nutrients and Energy in Dif- 
ferent Fooi> Materials at Average Prices 1 

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. 




Amounts for 10 Cents 

KlM> OF Material 

© s 


i) Ma- 





H P 

— z 

\ \ 

z ~ 
Z < 

of Foe 




C < 
< > 

w — 



r, nts 



Pou nds 





















Beef, shoulder clod . . . 


. i.» 







Beef, stew meat 









Beef, dried, chipped . . . 









Mutton chops, l<»iii .... 

























Pork, Bmoked ham . . . 

















< lodfish, dressed, fresh . . 









Halibut, fresh 

















Mackerel, salt, dressed . . 









Salmon, canned 









( >\ sters, 35 1 per qt. . . . 









Lobster, canned 















— ■ 


Eggs, 86^ per doz 










Milk. T c per <(t 

















Corn meal, granular . . 









Wheat breakfast food . . . 









< >at breakfast food .... 




1 33 




















Wheal bread 

















Beans, white dried . . . 
































Potatoes, 60 p per bu. . . . 


















5 00 







































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. 


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. 


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. 


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. 


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. 


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 


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. 


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 ? 



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- M a' 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 


JV— phalanges 

Figure 191. — Skeleton. 



Figure 193. - - Dia- 
gram of Bone 

Figure 192. 

mlcrophotograph of 


« w ^> 





Compare Figure 193. 

Figure 194. — Car- 

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. 



certain amount of bone has taken the place of this soft 

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 

The erect position of man gives to his skeleton important 
characteristics which the skeletons of other animals do 



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. 

Make a report on the skeletal structures of animals as follows : 



Crayfish . . 
Clam . 
Frog . . 
Man, etc. . . 



\. 1 1 

.i.n s 1 1 n 


I '- ■ \ -. 





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} r ers 

in the walls of the digestive tube, blood 

vessels, the bladder, and the like, and 

they are not under the control of the 


Figure 200. — Muscles 
of Upper Leg. 

Note how they are ar- 
ranged in bundles. 

Figure 201. — Vol- 
untary Muscle 

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. 



Figure 202. 

- Involuntary Muscle 

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 


,-. - - 

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? 







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 


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 



Sweai &land 

ood vessels 

Figure 205. — Diagram of Skin. 


several layers of cells. 'Nails and the hair grow from the 
outer layers. The sense of touch is in the skin. 


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 ? 



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 



















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 




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- 

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 

Note the branches of the 
bronchus and blood vessels on 
the right side. 


apple." The larynx is formed by several large pieces of 
cartilage lined with a mucous membrane. On the inside 

ical cords 

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- 



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. 


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£ 

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Figure 209. — Hot-air Heating. 
By Earl Hallenbeck. 



£>//?£ CT HEJT/HG 

be continued for hours before natural breathing is 

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, 


- OUT 



Room //vD^yr//V£ 

£)/&£ c T H£A T/HG 

Figure 210. — Steam Heating. 
By Earl Hallenbeck. 


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 i ncn i R 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 ve ins. 

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 



Figure 213. — Organs of Circulation. 

Veins, black ; arteries, with transverse lines. Left side of figure shows 
superficial vessels, while right side shows deeper vessels. 


carried by the plasma, although some of it unites with the 

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 

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 










Color in 


C P 

o 5 

o o 





>— < 




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- 




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, 


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 
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 


Showing the 

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. 


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 

:_ ";:To Back 

To Large Intestine 
-To Leg 

Figure 217. — Main Arteries 
of Frog. 


21 >3 

I I 

All to Back 

4^;;^ To stomach 



\ To Kid- 

' p^-^Jo Reproductive 

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 " 

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. 


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 


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- 

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- 

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 


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 



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 

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 

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. 




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. 


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 



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 



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. 




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. 



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 




.. 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 


Figure 225. — Micro-photograph of 

The nerve cells are black. 








* 3 

> °0 6* 

» O Oo 
>© © * 

»° ? . * ~ • • 



motor ce 



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. 


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 

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 


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. 


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- 



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- 
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 w T e 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. 


Figure 228. — How we see the Pencil. 


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 

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. 



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 

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. 





Tests in Target-Shooting in Swedish Army 


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 

Non-Drinking Days: 860 Bhots fired be- 
fore exhaustion 

Drinking Days: 2TS shot- fired before i I 

Alcohol taken 3o minutes before tesl vras 
amount contained in about l l / 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. 


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." 


22 1 


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 

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 °f 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 


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 



Assaults and Drink 

1,115 Assaults in Heidelberg, Ger., 1900-1904 
66.5'; Committed in Saloons 



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 

" 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. 



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 

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. 



Abstainers' Advantace 

In a Championship Walking Match 


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 

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. 


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 


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. 


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 



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. 



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 


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- 


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 w r ill 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. 


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 


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. 


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. 


Cutten, The Psychology of Alcoholism. 

Davenport, Heredity in Relation to Eugenics. 

Guyer, Being Well-born. 

Horsley and Sturge, Alcoholism and the Human Body 





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. 



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, 


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 f ever 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. 


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 ( .*. 



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 



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. 



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 


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 


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< 


* - ___ — 

■ ■ . ■ 

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. 


If such food is eaten, an intestinal disturbance usually 

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. 



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 


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. 


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 










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 


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. 


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 

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 


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 


scientific evidence which justifies the use of patent 
medicines, or of alcohol unless definitely prescribed by a 

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 



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 

J The 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. 



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 





















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 



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 

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. 



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 


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- 

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 



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. 


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. 


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 



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. 






Scarlet Fever 


Whooping Cough 




Typhoid Fever 


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. 


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 



Student Report 

Due to Some Plant 

or Animal 

Treatment by 






In the watei 





















— * 







Cold .... 






Measles . . . 

Whooping cough 



Typhoid fever . 











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 


— 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 


paupers at a cost of over one hundred million dollars per 
year." — Davenport. 


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. 


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 ? 

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. 





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 

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. 




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-kot p l: 

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 3 phe 




JAJ /''Testa 

Figure 254. — Parts 
of Bean Seed. 


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. 


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. 



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. 



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). 


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 . 
Etc. . 





IIili M AT 

llll.t M OS 



COTJ i.l - 

■ '■ B 


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. 



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. 


Figure 258. — Germination of Bean. 




Examine germinating seeds and young seedlings »>f various kind 

plants, and note their peculiarities in Bprouting as indicated below. 

Bean . 
Corn . 
Pea . 

Etc. . 

Ai:< ii 


Ai;i li HOI 

l'l'.i'MIMN I 


( 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's 1 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. 



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 

Make a record of the results as indicated below: 








Wheat .... 

Walnut .... 



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. 



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 



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. 





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 

Figure 262. 




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. 



Figure 264. — Fibrous Roots of 

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. 


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 


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. 


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 



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 


spongy layer 

lower epiaer mis 


air which enters through Figure 265. — Cross Siction of Bean 

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 

Showing net veins. 



cells of 


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 

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. 



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. 


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 


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 



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]) "i 1 ! 

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 

Showing how they strive for food 
and moisture. 



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. 



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 f 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 





'■ ' 

<* r J 

\ ■ 

J> 'U 

\ • 





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 

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 



Figure 275. — Seedlings. 

a, Horse-chestnut seedling ; b, Honey 

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 

Note the palmately compound leaves. 



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. 



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. 



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 

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. 




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. 

Carrot . 
Dahlia . 
Ivy . . 

Roots All 


Roots not 
A i.i. Dndeb- 



Kooi - 

FlBBOl - 

Booi - 

I A I. 


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. 





[ 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 

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- 

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. 



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- 


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. 




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. 



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 



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- 


Figure 295. 

Photograph of Sections 
of Wood. 


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. 


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. 



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. 



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. 

Record your observations in a report. 










































































Geranium . 


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 



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. 






Figure 302. — Pea 

Leaves modified in- 
to tendrils. 

Figure 303. — Leaf of Oak. 
Simple leaf. 

Figure 304. — Leaf 

of Elm. 

Simple deciduous 






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. 


Examine as many leaves as possible and record the facts which yon 
have learned about them in a report like the following : 


Lb A VK8 


] ) K< 1 1 1 1 • ■ 1 - 



Cherry . 


Lilac . . 

Ash . . 

Rose . 




Etc. . 

219. Comparison of a Monocotyledonous with a Dicotyledonous 

Plant. — 






Same structure. 



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. 


Scattered vascular 
bundles, no cam- 

Vascular bundles form rinp, 

phloem out. xylctn in. cam- 


bium between. 

Vascular bundles 

Vascular bundles pass to 

uiven off from 

branches and to leave 3. 

1 nodes, 

to leaves 




' Long, simple, and nar- 
Leaves. < No petiole, but clasp- 
ing base. 
Parallel veins. 


Broad, compound. 
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. 



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- 



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. 



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 

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. 



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 


:-;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. 


Figure 313. — Violet. 
a, cleistogamous flowers. 



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. 


Study flowers in field and laboratory, and record the results, using the 
following table as guide. 

Geranium . 
Castor bean 
Salvia . . 
Pansy . 
Etc. . . 

O 1= 
o K 

— — 

- - 


Stamens only 
in a Flower 

Pistils only 
IN a Flower 



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. 



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 



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 



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. 


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. 






























































Sweet pea . 

Dandelion . 


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- 



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 
w r ork 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 



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 

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. 





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 

A capsule. 


Figure 322. — Capsule of 

Figure 323. — Chestnuts. 
A dry fruit. 



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. 






Figure 324. — 
Dry Fruits. 

a, beechnuts ; 
b, acorn. 

Figure 325. — Vertical Section of 

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 



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. 



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 

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, 



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. 



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. 



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. 


Every season of the year affords material for this phase of plant study. 
Record your result as follows : 












.£ O 






r -r! 






Dandelion . . . 

Maple .... 

Burdock . . 

Cherry .... 


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. 


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. 


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 


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 



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 

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. 















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 


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 


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 

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- 

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. 


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 


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. 


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. 


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. 



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 




























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- u P °^ a six-parted perianth (calyx and 
of-the-Valley. corolla taken together), six stamens, and 



Figure 346. — X-ray of Easter Lily. 

a three-parted pistil. 

The fruit is a capsule. 

Lilies are cultivated 

chiefly for decorative 


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 u r i""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 



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 

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 

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 



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 


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 <*> earl y sta S e ; *>, 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 







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 

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. 




















Figure 357. — Self-heal 
A common weed. 

5 .. A ' 

5* 7» \V ' - . f* 

HA i 

. •* 

MSfn^ • x 

Figure 358, — Hedge Nettle. 



Figure 359. — Common White Daisy. 

for ornament. The foliage of all these plants is rank- 
scented, the leaves are alternate, and the flower five- 

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- 

Not all the flowering 



Figure 360. — Dandelion. 





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. 


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 

Ql'KSTlOXS 33' 


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 ? 



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 


Figure 363. — Pleurococcus. 

a, single cell; b, cell dividing; 
c and d, groups of cells. 


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). 


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. 


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 



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 ■■ ."-■■ ^ 



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 

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. 



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 

Figure 366. - - Microphoto- 
graph of Conjugating 


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. 



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. 


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 ? 


Atkinson, High School Botany. 
Bennett and Murray, Cryptogamic Botany. 
Bergen and Caldwell, Botany. 
Leavitt, Outlines of Botany. 


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 bacterium 1 under discussion. The spirilla 
and the bacilli often have on one or both ends tiny thread- 

1 Bacterium, singular of 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 


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 


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." 


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 petri 2 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. 


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 

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 



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. 



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 18 l J0 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. 



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. 



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 

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. 


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 



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. 


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. 


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 '.' 


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. 



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, 

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- 




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 

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). 


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. 



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 



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. 



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. 



- 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). 


Figure 385. — Spores. 

Section through a leaf 
injured by fungus. 


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 



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. 




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. 


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 

A farm fungus. 


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 


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 ? 


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. 



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 


Figure 389. — Types of Mosses. 



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 

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. 


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 


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 

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 

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. 


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, 



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. 


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. 



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. 


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. 


Leavitt, Outlines of Botany. 



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 

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 


Figure 394. Pteris. 



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 



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. 



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. 


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 




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). 





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. 


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 

Horsetail, or equisetum, -rows in waste or 'lamp pla< 

Figure 402. 

b, Sporangium ; 

c, Spores. 

Figure 403. — a. Club 




internode •- 


collar of... 


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 

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. 


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 <_ r as 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. 


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. 


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. 


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, | 



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 


ri.xL' v// /•;/■: 


Figure 407. — Staminate Strobili of 

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. 



Figure 409. — Ripe Cone of 

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. 



Moots. — The roots of the pine vary according to the 
kind of pine and according to the soil, but they are alwa 


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. 



are separated slightly. 
Then the scales close 
together, the cones turn 
downward, and con- 
tinue to grow for sev- 
eral months (Figures 

Fruit. — During the 
next year, the pollen 
grains which are shut 
up inside the scales 

Figure 414. 

Waste Land in Pennsyl- 

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 



Figure 416. — Fire Train in the Adirondacks. 

Figure 417. — Nursery Where Young Trees are Started. 



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 


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. 


N t: l I > I B8 


A i.i i:i:\ \ i i: • 


Needles is 

. i - 

-. \i ■ i no. 

in m « i bs 

i. \ 

3 m 


White Pine 


Cedar . 

Spruce . 

Etc. . . . 




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. 



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 


»»•»?■.«-— ^ j M ^ mt + ta^*-. . 


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 



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 



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 } T ear and apparatus for fighting fires is always in 

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 is 
taking steps to preserve her forests and also to re-forest 
large tracts which have been out over (Figures II s 120 >• 

■ " "H. 


N n 




e£ '..'. 


Figure 422. — Seed of Pine. 



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. 


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 ? 


Government pamphlets and bulletins. 
Hough, American Woods. 
Keeler, Handbook of Trees. 
National Geographic Magazine. 
Sargent, Trees of North America. 
Schenck, Forest Policy. 



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 


Figure 423. 

Photograph of Pitcher 



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 

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 

Figure 425. — Photograph of Sundew. 



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 



matter, usually wood, 
just below the soil. A 
fungus which grows on 
the roots helps them to 
absorb this prepared 

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 

Growing over the surface of a boulder. 



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 



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. 



Figure 432. — Giant Cactus. 

Figure 433.- Sage Brush. 



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. 



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 



^B^^B w^. ^ffC 

[j| \^ V 

Br ^^^fl| 

p >^ 



y+- jf 

Figure 437. — Long-spurri 



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 


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 


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 

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). 


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 

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 


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. 


. 40*1 


f ;£#" v«*tfd 


5 ■ "^* 



■ : '$$'$>' 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 tin 1 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 ; 


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. 



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- 

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 

Figure 441. — Calla. 

From an X-ray photograph. One of 
the new ways of studying plants. 


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." 


To show the response of stems 1 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. 



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 



i- S 











: Ttaltl 

MX ■ 


Ua \ 






Purple nncti 



I ■■ :■ : . 

ti adab 

! : i. 










dta • . 

.' :• 

Solden Crooned 

tree . 

. / 


.. ,/f 

fuscous fuscous qreenah forked 



r, ' 




? ..- 

; I >, -i >■ : 

■- -», 

//.. r'r 





: ■ "i 



■. me 

b*x h 



■ ."' 



nook '■■ 





. - 
: Eft 

r -xy.t 


scarlet scarlet black scortet sooner 


* Ural b«* lum rtc JVK«i«a g/*a •» mm* ttm r—mr 




Plate S- 

Dcuny Uoodpcckr 



— Report for feeding station — 









Light Above 
m bock doon 


-C; O 

Manner of — 
comina to food— 












/fairy rloodpccher 






Alignt Above 
uaiH doun 
Dead foremost 






Fly directly 
to food 


Brwn Creeper 


Alignt belocj 
ana ualh up 



Song sparrou 





Alight /tear 
ana hop nit 



House or 
English Sparrou) 









AIM Near 





Plate C- 

— Report f 

or Birds in 

Nesting Season — 
























grass and 
mud — 





Chipping Sparrou 


grass, hair 

1 1 







plant fibre, 
grass, string 






grass and 
uool — 






Neadou Lark 


grass - 




rr r» 




flair, mud 





F " 


Cat Bird 


grass — 






Mourning Dove 






House Sparrow 


hay. grass, 
feathers , 






P/ate D- 

— Pepori 

on a 

single ^a-r of Birds feedm. jng- 





Aumber of rimes eocfi 
/test ling is fed — 

Direction from uhich 
Adurts approach nest 


















3 20 

i * 









9 21 








9 28 










9 30 








9 40 








3 45 








9 47 


















Plate E- 

— Peport for Seasonal Activities of Birds — 









Color of young 

Color of /duff 













Chipping 5cmxj 

Gold finch 

Cedar Bird 


Song Sparrou 


Houx Spanvu 






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 

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. 



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 


be permitted to come in contact with or to visit any child 
who has not had such disease or any child in attendance at 

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 

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 


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 

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 : 


(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. 


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. 



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 


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- \\ 


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 

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 


patient that he takes a cancer out " by the roots," he is talking 

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 

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 


the cases are cured, that is, show no further appearance of the 

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 

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 

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. 


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 


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 ^ - > 




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 


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 


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 ■ '>}! 


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 



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 


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- 

source of liquors .... 
Barnacles, economic Impor- 
tance of (fig.) "i. i" 1 

Baseball, advantage of M i nt- 



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 


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 


complete metamorphosis of . . 

cutting comb from hive (fig.) . 


gathering of nectar by . . . 

honey, value of 

imperfect female (worker) . . 

members of Hymenoptera . . 


perfect female (queen) . . . 


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- 

field study of 

Belladonna, compared with 

source of 

Berries, produced by rose family 
Berry, a form of fruit .... 

collection of drupes .... 


illustration of (fig.) .... 

pepo, special kind of ... . 
Bichloride of mercury, use of 
Bilabiate flowers of mint . . 
Bile, a digestive juice .... 
Biological diseases, kinds of . 








f 35 






















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 





Black snake, a constrictor . 


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 (tiu r ) . . . . 
Brain, conl rol (fig.) 

efficiency, discussion of . . . 
conditions Decessarj for . . 

microphotograpb of ( fig > 
" Brain " of earthworm . . 


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 

temporary by-products of . . 
Breathing, in grasshopper . . 

in man 

not respiration 

Breathing center in develop- 
ing embryo 

Brewing, scientific basis of . . 


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 




- ■ 



. U * i 





22 1 

ll Hi 








References are to pages 

Bubonic plague, a bacterial 

disease 2.34 

Bud, in reproduction of yeast 

plant 356 

Budding 1 (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 


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 


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 


Central nervous system of 

frog (fig.) 118 

Central pith of wood 
Central stalk of fern frond 
Cephalopoda, classified . - . 
Cephalopods, group of mol- 



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 . . 










References are to pages 

Chinese silkworm 

Chipping- sparrow, useful 

food of 

Chloride of lime 

Chloroform, example of anes- 

action on lipoid 

Chlorophyll, in leaves of bean 

of pleurococcus 

Chloroplasts, containers of 


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- 

Circulation, effect of alcohol on 

in plants 

of mollusks 

organs of (fig.) 

Civilization, advanced by agri- 

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 . . 


example of pelecypoda . . . 

fresh water 

growing on oyster (fig.) . . . 
Clasping base, of corn leaf . . 

of grass leaves 

Classification, basis of, in Pro- 

of birds ... \ ..... . 

of plants by Linnaeus .... 

































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 

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 


Coating of hairs, use to Arctic 


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- 


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 


Codling moth, a harmful Lepi- 
doptera (fig.) 19 

complete metamorphosis of 
























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 


Consumption, treatment of 
Contact, movemenl caused bj 
Contractile vacuole of 


Coon ( fig.) 

Cooper h Hawk. > eonomii i 

tils of 

Copperhead snake .... 
Copper sulphate, in Fehling's 


Coral islands, formation of . 

Coral reefs 

Corals, example of « kBlent 
example of Ad Inozoa 

Core, in pome fruits .... 
Coriander, member of parsley 


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 .... 


smut . a parasite on corn . . 

a fungus 

spores of i fig.) .... 

Mem (fig. I 












References are to pages 


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- 


production, map of . . . . 

seed of (fig) 

source of clothing 

Cottony cushion scale . . . 

Cotyledon of corn 

Cotyledons, affected in bean 

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 . . . 


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.) 





































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 



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 


1 1 

/,■. t, r, net 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 


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 





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 


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- 

Deserts, habitat of plants 

Development of amphibians 120 

Development of tadpole, 
two stages In I ii-'. > . . 

Devil fish, example ot cephalo- 

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- 

Dicotyledons, group of plants 
represented by bean, squash, 


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 




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 


treatment of 

Diptera (order of insects) . . 


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 .... 



Disk, central, of starfish . . . 

sucking, of starfish .... 

Disk-flowers of composites . 

Dissected leaves of crowfoot 


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 












Dividing cells of pleurococ- 

Dividing egg, becoming tadpole 


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- 

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- 

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 

Drying fruit, purpose of . . . 

Dry season, effect of on annual 

Dry seasons, effect of, on size 
of cells . . 

Ducks, feet of 





















Eagle, a scavenger 
claws of ... 
head of (fig.) . . 
wings of . . . 





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 



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- 

Environment, denned .... 


illustrated by development of 


Enzyme, of gastric juice . . . 

of yeast plant 

secreted by bacteria .... 
Ephemeridae, an order of 


Epidemics, of diseases, costli- 
ness of 

sore throat (fig.) 

Epidermal tissue of pteris 


Epidermis, of agave, section of 


of bean root (fig.) 

of leaf (fig.) 272, 

of root 

of rootlets 

of xerophytes, character of . . 

outer layer of skin 


Epileptics, number of ... . 
Epiphytes, definition of . . . 

habitat of 

Epithelium, ciliated (fig.) . . 

columnar (fig.) 

flat (fig.) 

Eskimo, surroundings of . . . 
Esophagus, of crayfish . . , 















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 



/.'•/• n nee* 

Eyes, continued 

of frog lit 

of grasshopper 11 

of man, care of 217 

of Nereis .si 

of vertebrates 215 


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 


Fibers in blood 

Fibrinogen, in format ion of 

Fibrous roots, of buttercup 

of corn 

of grasses 

Fibrovascular bundles, cells 

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- 

Fires, forests destroyed by . . 

l>iv\ .niion of, by national g 


Fire slash (fig.) 

Fire train in the Adiron- 

dacks (fig.) 

Fireweed in plant bu< ssion 

Firewood, furnished by b 


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 ion of 




a . i 














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.) 


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 


Flowers, field and laboratory 
study of 

of bean, organs 

wind-pollinated . . . 
Flycatcher, great-crested 


Flycatchers, eaters of larvae . 

food of 

Flying squirrel (fig.) .... 
Fly pollinating wild carrot 


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 


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 










, 366 















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 
Freezing 1 , 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 


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 


Functions, definition of . . . 
Fundamental tissue of pteris 


Fung-i, action in changing lava 

1" --oil 

classified 7 

conditions favorable for 


summary of 

Fungus, an enemy of corn . . 

Furniture, lumber for .... 

Furs, as clothing 







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 




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 



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 


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 



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- 

Headwaters of rivers pro- 


Healthy bodies and bacteria 


Heart (fig.) 

and lungs (fig.) 


nuisi le ••■■Us t fig. i 

of craj fish 

valves of 

Heart and blood-vessel- 

Heart-shaped body, prothal- 

lium oi fern 

Heat and pressure. Influence 
of in forming coal .... 
Heating 1 , 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.) 



1 .7 




l l 




22 1 





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 


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 


Home making, work of women 
Home study of moths and 


Honey, amount of carbohydrate 

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- 

Hops, use of, in manufacturing 
of beer 

























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 



/,' 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 


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 . 



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 . . 


Inlnilent pores 

Inhalent siphon of clam . . . 


Inherited diseases .... 

Inner chamber of eye ui. 

Inner coat of pollen grain 

Inner ear (tig.) .... JIT, 


Inorganic foods 

Inorganic matter 







Insect, group, divisons of 


\ Lsitors, Btudj of 


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 









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 




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 


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 


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- 

Lingual ribbon 

Linnseus, work of 


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 


molted eX. .skeleton of I fig.) 




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 




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 


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 


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 



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 


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 

a dicotj ledon 

sc. (iiin--, of US 



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 



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 


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- (tiu r .) 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 


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- 


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) 

II . 















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 


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 

Pasteur solution, formula of . 

Patent medicines, defined . . 
to be avoided in consumption . 

Patrolling of forests .... 

Paupers, cost of supporting . . 

Pea plant, modified leaves of 


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 










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- 


Photosynthesis, finished prod- 

net of 

<-\ \ gen produced bj .... 
performed bj stem .... 
\ ital process In plants 

Phosphates 176, 

Phosphorus, a chemical ele- 


menl found in li\ ing thing* 

a poison 

in lipoid 


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 .... 



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 




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 



/,' /< 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- 

Pulse, caused i>\ beating ol 


Pulse, members of bean family, 
tnenl loned in Bible .... 
Pulse family, characterise 



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 tiu r .) 

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 .... 







Quack defined .... 

. . :\\ 

Quail, a seed eater . . . 


at w hole main -.tat ion 


- — » — • 

Quarantine, defined 




violation of 

2 17 

Queen bee (fig.) .... 



. . 



References are to pages 


Rabbits, destroyed by hawks . 

harmful animals 

young (fig.) 

Radial arrangement of star- 

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 



head of (fig) 

poison, effect of 

rattles of (fig.) 

Rats, destroyed by hawks . . 

harmful animals 

Raw materials of photosyn- 

Raw milk, danger from . . . 
Ray flowers of composites . 

Rays of starfish 

Rectum, part of digestive 


Red bud, member of pulse fam- 


Red clover pollinated by 
bumble bee 

Red corpuscles of blood . 197, 

Redheaded woodpecker (fig.) 

Red poll, at hemp and millet 

Red rust of wheat, a fungus . 

Red-shouldered hawk . . . 

Red-tailed hawk 

young of (fig.) 

Red- winged blackbird, food 



















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 


Reproductive glands of star- 

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 


























2 3 











/ \ 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 l r . S. 

member of grass family . . . 

use of, in China and India . . 

value of, as food 

Right shell of clam (tiu r .) . . 

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 


3-_'i ; 




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\ 301 

of radish (fig.) 


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 



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 


Sap, flow of, in spring .... 

Sap conducted laterally by 

medullary rays .... 

Sap tubes affected in bean 


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 

effect of drink on (fig.) . . . 


Sclerotic coat (fig.) .... 
Scorpions, example of Arach- 


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 . . . 













Sea-cucumber, member of 

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 


Seed, development of ... . 

distribution of 

of pine (fig.) 

of strawberry 

Seed-bearing plants, a group 
of plants 


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 


Seedlings, honey locust (fig.) . 

horsechestnut (fig.) .... 

maple (figs.) ..... 279, 

wheat (fig.) 

Seed-producing organs of 


Seeds, of berries 

changes in size made by cross 

devices for distributing . . . 

food of birds 

















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- 

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 


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 


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 



References are to pages 

Slug- (garden) 

Slugs, examples of mollusks 
Small cells, position of in annual 



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- 

flying (fig.) 

gray (fig.) 

Stagnant pool, breeding place 

for mosquitoes 

Stalk of grain of corn . . . 
Stamen, diagram of . . . . 
Stamens and pistils of | 


Staminate cones of pine . . 

Staminate flower 

of monoecious plants .... 

Ol willow ( tiu r - ) 

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 .... 


described (fig.) • • 



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 










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 


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 


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- 

Symbiosis, a dependent relation 


example of 

Symptoms, medicines in con- 
ned ion with 



i « 



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.) 


Tar. source of 

Tarsus of grasshopper's foot 
Tartar, effect on gums .... 
Tassel, staminate flower ol corn 

Taste cells (fig.) 

Technical names of of 


Teeth, milk (fig.) • • 

ol man 

permanent (fig.) 

Telegraph poles, use of gyTOr 
oosperms for 











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 


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 





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 . . . 





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 


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 

Twining stems 

Two-parted flower of mint 


Tympanic cavity 

Tympanic membrane . . 
Types, of mosses I fig. I . . 

of twigs (fig.) 

Typhoid fever, a bacterial <li: 


spread by carriers 

Typical fern, pteris .... 
Typical flowering plant, bean 


Ulmus americana 7 


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 



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 



References are to pages 

Vaccination, discussed . . . 
Vacuole, food, of amoeba . . 


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 


Vaseline, use of in transpira- 
tion experiment 

Vase-shaped organs (arche- 

gonia) of moss 

Vedalia, beneficial beetle . . 
Vegetable food, highest form 


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 



room at night, direct heating 


indirect heating (fig.) . . . 
room in daytime, direct heat- 
ing (fig.) 

indirect heating (fig.) • . • 
Ventral blood vessel of earth- 

























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 


Walking sticks 20 

Walnut, family discussed , . 327 

I \ hi \ 


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 




'//•■ 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 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 


White grubs eaten by birds 

White of the eye 

White pine, value of ... . 
White-throated sparrow 

hemp and millet station . . n> 
Whole grain station, 

frequent ing 149 

Whooping cough, a bacterial 

e\posUle t0 

Wigglers. larva- of mosquito*-* 19 
Wild plants, Improvement of by 


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 


Wing of pine seed 
Wings, ol birds .... 

Is ^'' 



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 



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 


% C State CWIejfe