1M8 ■ ;: Jpr it'.IHI' W\t -0. p. J!tU phrarg •»♦• QH506 fif>7 N.C. STATE UNIVERSITY D.H. HILL LIBRARY S00366687 Date Due •- Feb23'34 L Wf 19Ar>J1C ~ \ FEB 1 7 1QA? MAY vm 19750 «ne as ?&5 l^RLZZ^ 200M/06-99-991212 Elms at the Water's Brink. PRACTICAL BIOLOGY BY W. M. SMALLWOOD SYRACUSE UNIVERSITY IDA L. REVELEY WELLS COLLEGE GUY A. BAILEY GENESEO STATE NORMAL SCHOOL -oojojoc- ALLYN AND BACON Boston Neto gork Chicago COPYRIGHT, 1916, BY W. M. SMALLWOOD, IDA L. REVELEY AND GUY A. BAILEY ADR Notijjooli UJregg J. S. Cushing Co. — Berwick & Smith Co. Norwood, Mass., U.S.A. ( PREFACE Practical Biology offers a simple, workable, attractive, flexible, and teachable course in Biology. Simplicity is a feature of the book. The language is simple, not technical, and the style is easy, flowing, and colloquial. The pupil is assisted by many mechanical helps. Small cuts or larger pictures illustrate each new topic and there are many charts and maps. The practical aspects of Biology are emphasized. A study is made of the economic value of plants and animals, and of the characteristics which make them beneficial or harmful to mankind. * The attractive illustrations, many of which were made es- pecially for the book, are a feature of the Biology. In addi- tion to the cuts and pictures which illustrate the text, there are portraits of the leading biologists of the world, with brief accounts of their lives and of their contributions to the subject. The flexibility of the book enables teachers to begin with the study of animals or with the study of plants. A number of features help to make Practical Biology teach- able, (a) The paragraphs are short, and there are summaries and questions at the end of each chapter, (b) Well-known types like the grasshopper and the bean plant are studied first, and the treatment passes from the known to the unknown, (c) The pronunciation and derivation of technical names are given in the text the first time the names occur, (cl) There is an introduction defining the common scientific terms used in the study of Biology, (e) Optional field work and students' reports are provided for. (/) Laboratory work is contained iii iv PREFACE in the book, so that a special manual is unnecessary, (g) The index is unusually complete. The treatment of human biology emphasizes hygiene and sanitation and contains graphic diagrams illustrating the sec- tions on health and disease. This treatment will be found especially practical. The treatment of alcohol and narcotics is adequate, but sane. For teachers in New York State a feature of the book is its close relation to the Regents' Syllabus, which it covers exactly. It is equally suited to courses laid down for various other states, notably Massachusetts and Ohio. The book has a number of appendices, one of which has to do with bird study. Another contains the sanitary code of the State of New York. The work is so arranged that the course, though simple, is thoroughly scientific. Science is organized knowledge, and the simple student reports in the form of tables lead the pupil to make a correct and logical classification of his facts, thus laying the foundation for scientific study. W. M. S. I. L. R. G. A. B. July, 1916. ACKNOWLEDGMENT OF ILLUSTRATIONS Guy A. Bailey, Bird and Mammal Photographs (in nature). Fred Baker, New York State College of Forestry, 406. Hugh P. Baker, New York State College of Forestry, 411, 414. M. W. Blackmail, New York State College of Forestry, 2, 127, 128. S. S. Berry, 100. G. Sidney Britton, Syracuse, N. Y., 145, 146. W. E. Britton, Connecticut, Agriculture Station, 27. W. Coe, Yale University, 73, 74. Conservation Commission, N. Y. State, 412, 413, 415, 416, 417, 418, 419, 420. Hugh Findlay, College of Agriculture, Syracuse University, 17, 18, 308, 330, 348, 355, 357, 358, 359, 362, 435, 436, 437. Hugh Findlay and Dr. I. H. Levy, 346, 441. Fitzhenry-Guptill Co., Boston, 16. Geneva Experimental Station, N. Y., 383, 384, 385. Illinois State Laboratory of Natural History, 430, 431. J. E. Kirkwood, University Montana, 1. Dr. J. S. Marshall, Berkeley, Cal., 182, 183. D. F. MacDougal, Desert Laboratory, Tucson, Arizona, 432. S. O. Mast, Johns Hopkins University, 49. N. Y. State Bureau of Health, 238, 242, 243, 244, 245. Dr. Edward Packard, Saranac Lake, N. Y., 239, 240. Parrott and Fulmer, Geneva Experimental Station, N. Y., 10. F. C. Paulmier, Albany, N. Y., 87, 88. Dr. C. Potter, Syracuse, N. Y , 185, 186, 195, 196, 197, 198, 199. L. Pennington, New York State College of Forestry, Syracu^ . N. Y., 380, 381, 382. v VI ACKNOWLEDGMENT OF ILLUSTRATIONS A. M. Reese, University West Virginia, Morgantown, W. Va., 133, 134. A. G. Rutheven, University Michigan, Ann Arbor, 131, 132. G. B. Simpson, Albany, N. Y., 14, 93, 94, 95. B. G. Smith, Ypsilanti, Michigan, 113. W. H. Snyder, Los Angeles, 42, 123, 135, 159, 167, 176, 177, 222, 241, 280, 433, 440. Syracuse Universit}^, Agricultural College, 246, 247. Crystal Thompson, Ann Arbor, Michigan, 114. J. M. Thorburn & Co., New York City, 220, 278, 279, 297, 298, 329, 361, 378. C. H. Townsend, N. Y. Aquarium, 105, 106, 107, 108. U. S. Census 1910, 248, 340, 343, 344, 352, 356. U. S. Department of Agriculture, 7, 9, 11, 12, 13, 19, 33, 34, 35, 37, 38, 39, 43, 44, 56, 85, 96, 102, 103, 111, 112, 171, 172, 173, 269, 270, 290, 293, 294, 295, 315, 337, 345, 349. Jerome Walker, Physiology, 213, 220, 221. Anti-Saloon League, 230, 231, 232, 234. TABLE OF CONTENTS PART I ANIMAL BIOLOGY PAGE Introduction 1 CHAPTER I. The Grasshopper. A Representative Animal . . .11 II. Other Common Insects 24 III. The Simplest Animals — Protozoa 45 IV. The Simpler Metazoa 55 V. Ccelenterates, Hydra-like Animals 63 VI. The Starfish Family. (Optional) 71 VII. The Worm Group 76 VIII. Crustaceans and Related Forms 86 IX. The Mollusks 94 X. Fishes 103 XI. Amphibians 113 XII. Reptiles 129 XIII. Birds 136 XIV. Mammals 150 PART II HUMAN BIOLOGY XV. Life Processes of Man 161 XVI. The Skeleton and Muscles . . . . . . .184 XVII. Respiration, Blood, and Excretion 192 XVIII. The Nervous System of Man . ... 209 XIX. The Biology of Disease .... ... 232 19722 vm TABLE OF CONTENTS PART III PLANT BIOLOGY CHAPTEE PAGE XX. Typical Flowering Plants ....... 259 XXI. Other Flowering Plants 323 XXII. The Simplest Plants 338 XXIII. The Smallest Plants (Bacteria) ...... 343 XXIV. Fungi 354 XXV. Mosses and Their Allies 364 XXVI. Ferns and Their Allies 369 XXVII. The Conifers (Gymnosperms) 376 XXVIII. Peculiarities of Plant Life ....... 389 Appendix A 405 Bird Study. Appendix B 408 Sanitary Code of New York. Appendix C ...... <> ...» 414 Cancer. LIST OF ILLUSTRATIONS Elms at the Water's Brink Frontispiece FIGURE PAGE 1. Simple Osmometer 3 2. Plant Cell 4 3. Animal Cell 4 4. Tissue ............ 5 5. Diagram : Showing proportion of chemical elements in living things 8 6. Female Grasshopper 11 7. Diagram : Showing main parts of the grasshopper ... 13 8. Mouth Parts of the Grasshopper . . . . . . .14 9. Grasshopper Laying Eggs . . . . . . . .15 10. Incomplete Metamorphosis of the Tree Cricket .... 17 11. Codling Moth Larva 17 12. The Worm in the Apple 18 13. Codling Moth Pupa . 18 14. Codling Moth 19 15. Monarch Butterfly 20 16. Modern Spraying Outfit 21 17. Plant Lice on Fern 24 18. Mealy Bug 25 19. Cicada, Adult and Nymph 25 20. May Beetle 26 21. Eggs of Ladybug ........ 26 22. Holes Made by Woodpeckers ...... 27 23. Redheaded Woodpecker 28 24. Larva of Mourning Cloak Moth 28 25. Transformation of Pupa of Mourning Cloak Moth into Adult . 29 26. Cecropia Moth 30 27. Young Tobacco Worm . ... 30 28. Larvae of a Leaf Miner • • .31 29. Cedar Bird 30. A Geometrid Moth ..... . .32 31. Protective Coloration 33 32. Yellow Swallowtail . 33 ix X LIST OF ILLUSTRATIONS FIGURE PAGE 33. Honey Bee : Worker ; Queen ; Drone 34 34. Queen Cell 35 35. Honey Bee Egg ; Young Larva; Old Larva ; Pupa ... 35 36. Honey Bees Clustering at Swarming Time 36 37. Capturing a Swarm 37 38. Model Apiary 38 39. Cutting Combs from Box Hive 39 40. Ichneumon Flies 40 41. Adult Horn-Tailed Saw-Fly 40 42. Common Housefly 41 43. Eggs and Larvae of Culex 42 44. Adult Culex ; Adult Anopheles 42 45. Microphotograph of an Amoeba ....... 47 46. Diagram of an Amoeba 48 47. Amoeba Reproducing by Fission .49 48. Diagram of Paramoecium 50 49. Paramoecium 51 50. Paramoecium Reproducing by Fission 51 51. Vorticella 52 52. One of the Foraminfera . 52 53. Some Flagellate Protozoa 52 54. Gonium . . . . . . . . ... .55 55. Volvox 56 56. Bath Sponge 58 57. Diagram : Showing parts of sponge ...... 59 58. Spicules of Lime 59 59. Two Stages in the Development of the Sponge 60 60. Microphotographs of Hydra 63 61. Diagram of Body of Hydra . 64 62. Microphotograph of Body Wall of Hydra 64 63. Diagram of Cell Layers ........ 65 64. Microphotograph of the Hydroid Obelia 66 65. Diagram of the Hydroid Bougainvillea 66 66. A Hydroid Colony that Looks Like a Plant 67 67. A Hydroid Medusa 67 68. The Medusa Known as Pelagia '67 69. Pennaria Tiarella . 68 70. Some Common Corals . 69 71. Starfish 71 72. Diagram of Body of Starfish 72 73. Anatomy of the Starfish 72 74. Purple Sea Urchin 74 LIST OF ILLUSTRATIONS XI FIGURE PAGE 75. Sea Lily . , . 74 76. A Planarian Worm 77 77. Trichinella 78 78. A Common Tapeworm ........ 78 79. Hair Worm in the Body of a Grasshopper .... 79 80. Diagram of the Organs of Earthworm from the Side . . 81 81. Earthworm . 82 82. Dero 84 83. Crayfish Bearing Eggs ........ 86 84. Crayfish . ' . 87 85. Molted Exoskeleton of Lobster 87 86. Organs of Crayfish 89 87. Soft-Shell Crab 91 88. Pill Bug . 91 89. Cyclops . . .... ... 91 90. Daddy-Long-Legs ..... ... 92 91. Spider 92 92. Thousand-legged Worm ; Centipede ..... 92 93. Clam ; Showing Foot 94 94. Right Shell of Clam 95 95. Digestive Tube of Clam 95 96. Embryo of Clam 97 97. Snail 98 98. Tongue of Snail 98 99. Snail Shells 99 100. An Octopus 99 101. Soft-Shell Clam 100 102. Stages in Life History of Oyster 101 103. Barnacles and Clams Growing on Oysters . . . .101 104. Skeleton of Fish . 103 105. Perch 104 106. Sunfish, or Pumpkin Seed .104 107. Catfish, Bullhead, or Horned Pout . . . . . .105 108. Brook Trout 106 109. Scales of Fishes . . . . ■ 107 110. Eggs of Land-Locked Salmon 110 111. Young Fish ; Showing Yolk Sac .111 112. Young Fish Fry Ill 113. Some Common Salamanders 113 114. Common Frog 114 115. Diagram to Show Organs of Frog 116 116. Kidneys of the Frog .... . .117 Xll LIST OF ILLUSTRATIONS FIGURE PAGE 117. Central Nervous System of Frog . ... 118 118. Frog Eggs : ... 121 119. Diagram Illustrating Fertilization in Frog Egg . . . .121 120. Dividing Egg of Frog 122 121. Dividing Egg Becoming a Tadpole 122 122. Two Stages in the Development of Tadpoles .... 123 123. Fossil Shells of Animals Now Extinct 124 124. Tree Frog 126 125. A Sea Turtle 129 126. Horned Toad, a Lizard 129 127. Bull Snake with Hen's Egg in Mouth 130 128. Bull Snake after Swallowing Egg 130 129. Head of Rattlesnake 131 130. Rattles of Rattlesnake 131 131. Rattlesnake — Poisonous 132 132. Garter Snake — Harmless 133 133. Eight-Foot Florida Alligator ....... 133 134. Alligator Nest 134 135. Poisonous Lizards ; the Gila Monster 135 136. Grebe . . ... . • 136 137. Herring Gulls 137 138. Adult Screech Owl 138 139. Skeleton of Mallard Duck .138 140. Different Kinds of Birds' Feet ....... 139 141. Loggerhead Shrike 139 142. Young of Red-Tailed Hawk — Beneficial ..... 140 143. Head of Young Eagle 140 144. The Robin 141 145. Nest of Yellow Warbler 142 146. Nest of Bittern 142 147. Mourning Dove . .143 148. Chimney Swift and Nest „ 144 149. Junco . 144 150. Female Bobolink 145 151. King Bird . 145 152. Young Crows in Nest 146 153. Kingfisher 146 154. Hairy Woodpecker Eating Suet 147 155. Male and Female Cowbirds 147 156. Plan for Bird House 148 157. Plan for Bird House .148 158. Skeleton of Dog . 150 LIST OF ILLUSTRATIONS Xlll KIGl'RE Leaving Its Nest Deer 159. Coyote 160. Gray Squirrel 161. Young Gray Squirrel 162. Young Foxes 163. Bat Hibernating 164. Brown Bat 165. Flying Squirrel . 166. Deer Mouse 167. Sea Lions . 168. Stomach of Sheep 169. Skunk 170. Young Rabbits . 171. Elk . 1 72. Virginia Deer 173. Fawns of the Virginia 174. Coon . 175. Young Woodchucks 176. Camel ; the Ship of the Desert 177. Buffalo .... 178. Alimentary Canal of Frog . 179. Alimentary Canal of Man . 180. Tongue .... 181. Taste Cells 182. Milk Teeth 183. Permanent Teeth 184. Pear-Shaped Human Stomach 185. X-Ray Photograph of Human Stomach 186. X-Ray Photograph of Appendix and Part o 187. Gastric Gland ..... 188. Microphotograph of Stomach 189. Diagram of Villus .... 190. Home-Made Apparatus to Show Osmosis 191. Skeleton 192. Microphotograph of Bone . 193. Diagram of Bone Structure 194. Cartilage 195. X-Ray of a Normal and a Broken Elbow 196. X-Ray of Hand of Child . 197. X-Ray of Hand of Adult . 198. Broken Femur ..... 199. Same Bone Ten Weeks Later . 200. Muscles of Upper Leg f Large In testine PAGE 150 151 151 151 151 152 152 153 153 154 154 154 155 156 156 157 157 158 158 163 165 165 165 166 167 168 168 169 169 170 174 175 184 185 185 185 185 186 186 187 187 188 XIV LIST OF ILLUSTRATIONS FIGURE 201. Voluntary Muscle Cells 202. Involuntary Muscle Cells . 203. Heart Muscle Cells .... 204. Various Forms of Cells in Human Body 205. Diagram of Skin .... 206. Lungs and Heart .... 207. Voice Box, or Larynx 208. Diagram of the Diaphragm 209. Hot-Air Heating .... 210. Steam Heating 211. Microphotograph of Blood of Frog 212. Diagram of Work of the Capillaries . 213. Organs of Circulation 214. Heart 215. Diagram of Vein .... 216. Diagram of Capillaries 217. Main Arteries of Frog 218. Main Arteries of Man 219. Superficial- Lymphatics of Arm and Hand 220. Section of Kidney .... 221. Diagram showing Artery, Vein, and Kidney Tube 222. Nervous System of Man 223. Nerve Cells 224. Nerve Cells 225. Microphotograph of Brain . 226. Diagram to show Reflex Action 227. Section of Eye .... 228. How We See the Pencil 229. Plan of Ear 230. Statistics : Skill and Endurance Impaired by Drink 231. Statistics: Drink Impaired Scholarship 232. Statistics : Assaults and Drink . 233. Brain Control 234. Statistics : Abstainers' Advantage 235. Chart on Smoker's Heart (I) 236. Chart on Smoker's Heart (II) 237. Chart on Smoker's Heart (III) . 238. Deaths from Communicable Diseases 239. Tuberculosis Cure, Summer 240. Tuberculosis Cure, Winter 241. Malarial Swamp .... 242. A Model Reservoir .... LIST OF ILLUSTRATIONS XV FIGURE 243. A Poor Reservoir 244. Diagram : Thirty Years of Diphtheria in New York State 245. Diagram : Story of Epidemic of Septic Sore Throat at Rockville Centre, L. I. 246. Model Dairy Cow 247. Model Dairy Stable . 248. Map Showing Number of Dairy Cows on April 15, 1910 Agar Plates Bacteria and Mold 249. 250. 251. 252. 253. 254. 255. 256. 257. 258. 259. 260. 261. 262. 263. 264. 265. 266. Milk Diluted to j^Vo Bean Plant .... Photograph of Bean and Pea Parts of Bean Seed Diagram of Corn Seed Sunflower Seed . Squash Seed Germination of Bean . Bean Plants Sections of Bean Root Root Hairs .... Root Cap .... Bean Roots Fibrous Roots of Buttercup Cross Section of Bean Leaf Leaf Skeleton 267. Epidermis of Leaf 268. Germination of Corn . 269. Rootlets of Two Corn Plants 270. Corn Plant .... 271. Maple Seedlings . 272. Microphotograph of Corn Stem 273. Stem of Corn 274. Older Maple Seedlings 275. Seedlings .... 276. Older Horse-Chestnut Seedlings 277. Wheat Seedlings 278. Roots of Radish . 279. Roots of Beet 280. Alfalfa Root 281. Aerial Roots of Ivy 282. Potato Farms and Ranges i'aci: 241 242 243 247 248 249 250 251 252 259 260 260 262 262 262 264 267 268 269 269 270 271 273 273 274 277 277 278 279 279 280 280 281 281 28? 282 283 283 284 285 XVI LIST OF ILLUSTRATIONS 308. 309. 310. 311. 312. 313. 314. 315. 316. 317. 318. 319. 320. 321. 322. 323. FIGURE 283. Dahlia Roots ..... 284. Microphotograph of Sunflower Stem . 285. Cleft Grafting ..... 286. Whip Grafting 287. Budding ...... 288. Twining Stem of Dodder . 289. Creeping Stem of Trailing Arbutus 290. Horse-Chestnut .... 291. Types of Twigs ..... 292. Cherry Twigs . 293. Sections of Woody Stem 294. Wood of Spruce 295. Photograph of Sections of Wood 296. Food Storage 297. Celery Plant 298. Cabbage Plant 299. Twining Petiole of Clematis 300. Twining Petiole of Nasturtium . 301. Barberry Leaves .... 302. Pea Plant 303. Leaf of Oak 304. Leaf of Elm 305. Diagram of Bean Flower . 306. Diagram of Stamen and Pistil . 307. Sweet Pea Flower .... Fly Pollinating Wild Carrot Swallow-Tail Butterfly Pollinating Persian Corn Flower with Pistils Pollen Grains ..... Pistillate and Staminate Flowers of Willow Violet Two-Parted Flower of Mint Lady Slipper Flower of Columbine .... Salvia Easter Lily ...... Fruit of the Bean .... Fruit of the Corn Fruit of the Poppy Capsule of Violet Chestnuts . 324. Dry Fruits Lilacs PAGE 285 286 286 287 287 288 288 288 289 289 289 290 290 291 292 292 292 292 293 294 294 294 296 297 298 298 299 299 300 301 301 303 303 304 306 306 307 307 303 308 308 309 LIST OF ILLUSTRATIONS XV11 FIGURE 325. Vertical Section of Apple . 326. Cross Section of Apple 327. Cross Section of Orange 328. Forms of Dehiscent Fruits 329. Fruits with Hooks 330. Burdock in Blossom . 331. Fruits Distributed by Wind 332. Other Fruits Distributed by Wind 333. Fruits and Seeds 334. Milkweed Plant .... 335. Seed of Cotton .... 336. Bean Plant Injured by Bacteria . 337. Beans Damaged by Weevils 338. A Field of Beans 339. Peanuts 340. Map of Corn Production 341. Walnut Tree 342. Map of Production of Oats 343. Map of Wheat Production 344. The Cereals 345. Lily-of-the-Valley 346. X-Ray of Easter Lily . 347. Leaves and Bud of Beech 348. Wild Columbine . 349. Stamens and Pistils of Rose 350. Rose Flower Turning into a Fruit 351. Thorns of Rose .... 352. Map of Production of Orchard Fruits 353. Stipules of Rose Leaf . 354. Flower of Mallow 355. Water Horehound 356. Map of Cotton Production . 357. Self-Heal . 358. Hedge Nettle 359. Common White Daisy 360. Dandelion . 361. Map of Potato Production 362. Canada Thistle . 363. Pleurococcus 364. Spirogyra . 365. Spirogyra Conjugating 366. Microphotograph of Conjugating Spirogyra PAGE 309 309 310 310 311 311 312 312 312 313 313 315 315 317 318 319 323 324 325 326 326 327 327 328 328 329 329 330 331 331 331 332 333 333 334 334 335 336 338 340 340 341 XV111 LIST OF ILLUSTRATIONS FIGURE 367. Forms of Bacteria 368. Soil Bacteria 369. Clean Milk . 370. Dirty Milk . 371. Beef Jelly . 372. Beef Jelly . 373. Bad and Good Bottling 374. Yeast .... 375. Fermentation Tubes . 376. Bread Mold 377. Mold Grown from Water 378. Cap Fungi . 379. Puffballs . 380. Puffballs . 381. Bracket Fungus . 382. Tree Killed by Bracket Fungus 383. Pear Scab . 384. Section through the Scab 385. Spores 386. Lichens . 387. Section of Lichen 388. Spores of Corn Smut . 389. Types of Mosses . 390. Diagram : Life History of Moss 391. Antheridial Plant 392. Archegonial Plant 393. Marchantia . 394. Pteris . 395. Pteris Stem 396. Sori . 397. Sori Enlarged 398. Forked Veins of Fern 399. Sporangia . 400. Position of Sori ; Section of Sorus 401. Life History of Fern . 402. Sporangium ; Spores . 403. Club Moss . 404. Horsetail 405. Selaginella . 406. Conifers 407. Staminate Strobili of Pine 408. Young Cone of Pine . PAGE 343 344 348 349 350 351 352 355 355 357 357 357 358 358 359 359 359 359 360 361 361 362 364 365 365 365 367 369 370 370 370 371 371 372 372 373 373 374 374 376 377 377 LIST OF ILLUSTRATIONS XIX Pennsylvania FIGURE 409. Ripe Cone of Pine 410. Other Cones 41 1. Forest of Hard Woods and Conifers in Northern 412. Lumbering in New York .... 413. Fire Slash ....... 414. Waste Land in Pennsylvania 415. Waste Land 416. Fire Train in Adirondacks .... 417. Nursery where Young Trees are Started 418. Planting Young Trees in the Adirondacks . 419. Young Plantation in the Adirondacks . 420. Young Plantation Sixteen Years after Planting 421. Pollen of Pine . 422. Seed of Pine 423. Photograph of Pitcher Plant 424. Leaves of Pitcher Plant 425. Photograph of Sundew 426. Diagram of Sundew . 427. Venus's Fly-Trap 428. Photograph of Birch Roots. 429. White Waterlily . 430. Waterlilies ; Hydrophytes . 431. Cat-Tails .... 432. Giant Cactus 433. Sage Brush .... 434. Diagram : Showing Epidermis o 435. Bull Thistle 436. Lady Slipper 437. Long-Spurred Violet . 438. Mistletoe .... 439. Diagram of Sectional View of a Branch Infected with Mistletoe 440. Tropical Vegetation 441. CallaLily .... Agave, a Zerophytic Plant PAGE 378 378 379 380 380 381 381 382 382 384 385 386 387 387 389 390 390 391 391 392 392 393 394 395 395 396 396 397 397 398 399 401 403 PORTRAITS OF PROMINENT BIOLOGISTS Darwin Agassi z Huxley Koch . Linnaeus Pasteur IM IM. v \..r . 30 . 100 . 170 . 235 . 303 . 348 INTRODUCTION DEFINITIONS OF COMMON BIOLOGICAL TEEMS Biology is the science which discusses living things — ■ plants, the lower animals, and man. These living things move, breathe, feel, and get their food in varied ways. Man, for instance, does not move as a jellyfish moves, nor does he breathe as a tree breathes. He has not the same sensations as a frog, nor does he get his food as do the flowers ; though lie and all other living things have these functions1 in common. Each living thing has its parts especially adapted to its peculiar needs. Claws serve a cat admirably for climbinor and for catching mice; a frog has web feet to aid in swimming ; while hands are better suited to the kind of things that a man has to do. Energy. — Everything that plants and animals do re- quires energy. Without energy in some form they can- not move or grow. Energy is produced in various ways. In a steam engine fuel is consumed or oxidized to make energy. In man the food taken into the body is con- verted into energy by a slow kind of burning which we call oxidation. Life Processes. — From the study of physiology we are fairly familiar with foods, or nutrients, as they are some- times called. Some of these are starch, sugar, fats, oils, and mineral matter. The life of a plant or of an animal is directly dependent upon its food. But food is not the 1 Function has a scientific use in biology, where it is used to describe the common living activities of animals and l>'antMMMMH7 f Bwn 1 * C State Oik* 2 INTRODUCTION only important thing to consider in studying its life. The life of each plant or animal may be studied under eight headings, known as life processes. These are sensa- tion or irritability, locomotion, food getting, digestion, assimi- lation, respiration, excretion, and reproduction. 1. Sensation (irritability') is that life process by means of which an organism comes to know of things outside of itself. Through sensation (irritability) it becomes aware of its food. By the help of the senses the higher animals are able to see and hear one another, are conscious of heat, cold, light, sound, and many other things, all of which are called stimuli. 2. Locomotion is the life process by which animals move, and is closely related to sensation. It is the means by which animals secure food. In the higher animals stimuli are sent through the nervous system to the various muscles, which contract and so cause the animal to move. 3. Food getting needs no definition. Man gets his food from many sources. He eats animals, minerals, and vege- tables. Lower animals live by hunting or grazing, and plants get their food through their leaves and roots. 4. Digestion is the life process which prepares the food to pass to all parts of the body. It takes place in all animals and plants, but we are most familar with it in man. Man chews his food in the mouth, thus softening it and mixing it with saliva ready for the stomach. Di- gestion is continued in the stomach and completed in the intestine. As soon as the food is digested, some of it passes through a thin membrane in the wall of the intestine into the blood vessels and thus is ready to furnish energy in the body. This passage of the dissolved food through a mem- brane is called osmosis (os-mo'sis). 5. Assimilation is the building of the digested food LIFE PROCESSES into living animal and plant parts. In animals the blood vessels, into which the digested food passes, carry it to all parts of the body, and as it circulates, each part takes the food needed and builds it into living material. 6. Respiration is the life process that uses oxygen taken from the air or water and forms a waste product known as carbon dioxide. This life process should not be confused with breathing, which is limited to animals with lungs or air- tubes. In such animals the breathing is simply a mechanical process in which the air is brought into the lungs or air-tubes. This allows the oxygen to pass by diffusion into the blood, where it is carried to all parts of the body, or it may pass directly to the living cells. See section 6, page 14. 7. Excretion is the life process in which waste products, like perspiration, are made and cast off by the body. On page 1 we saw that energy was pro- duced by oxidation. After this the waste is thrown off by excretion, as the ashes are thrown out of a steam engine. 8. Reproduction is the life process by means of which each generation of plants and animals is brought forth. There are two kinds, asexual (a'sex-u-al) and sexual. Figure 47 on page 49 shows a simple animal, the amoeba (a-me'ba), dividing into two young amoebae by asexual methods. The same kind of reproduction in a simple plant, the yeast, is illustrated in Figure 374, page 355. Figure 1 . — Simple Osmometer show- ing Osmosis. The water in the glass passes through the egg-membrane and forces the egg- white up in the glass tube ; while the egg- white does not pass out into the sur- rounding water. INTRODUCTION Figure 2. — Plant Cell. Sexual reproduction is the name given to a process in which two special cells, called the egg and the sperm, unite to form one cell, the fertilized egg cell. The fer- tilized egg grows into the new organism. In some plants the fertilized egg forms part of a seed which later develops into the plant. These eight life processes are seen in all forms of liv- ing things, but it is often hard to stuclv them. For instance, the locomotion of a clam is harder to study than that of a cat, and the respiration of a plant than that of a man. The Parts of Bodies. — These life processes tell us what the parts of bodies do, but they tell us nothing about these parts them- selves. There are four words which are used in biology to describe these parts. They are: cell, tissue, organ, and organ system. 1. The Cell. —When the bi- ologist takes apart the plant or animal as you used to take down your block houses, he finds that he can separate the parts until he comes to a unit so small that a microscope is necessary to see it. These microscopic parts are called cells and are alike in the following respects : each one has a clear Figure 3. — Animal Cell. THE PARTS OF BODIES outer portion called the cell wall which incloses a mass of substance known as protoplasm (pro'td-plaz'm : Greek, protos, first; plasma, form). The protoplasm is made up of a substance called cytoplasm (sl'tu-plaz'm : Greek, kytos, hollow place ; plasma, form), in which is held a saclike body, the nucleus (nu/kle-us : Latin, nucleo, to become hard). The nucleus usually contains one or more separate bodies called nucleoli (nfi/kle-6-li). A cell is therefore defined as a mass of protoplasm composed of cytoplasm and nucleus (Figures 2 and 3). 2. Tissue. — The cells are of many shapes and sizes, and in the bodies of all but microscopic plants and animals are united to help the plant or animal carry on its life processes. This union of cells to do a certain work is called a tissue, and the usual definition is : a tissue is a group of simi- lar cells that do a similar work (Figure 4). 3. Organs. — In all of the higher animals the tissues are united into skin, arms, stomach, and so on, or in plants into leaf, branch, etc. Such struc- tures are called organs ; an organ is defined as a group of tissues that do a given work in the animal or plant. 4. The Organ System. — When different organs com- bine to carry on such a general life process as digestion, all of the parts that assist in this process are described as an organ system, as the system of digestive organs (Fig- ures 178 and 179, pages 163 and 165). Figure 4. — Tissue. Compare these cells with Figures 2 and 3. 6 INTRODUCTION These four expressions, cell, tissue, organ, and organ sys- tem, describe the materials of plants and animals which carry on the eight life processes referred to above. We shall read more and more about them as our study of biology progresses. Classification of Living Things. — Our study of biology cannot progress far before we see the need of classifying animals and plants. Animals are generally grouped in two divisions : invertebrates (animals without backbone) and vertebrates (animals with backbone). Plants are also divided into two groups : cryptogams (flowerless and seed- less plants) and phanerogams (flowering or seed-bearing plants). Below is given a detailed reference table of these classifications. I. Invertebrates. Animals without a backbone. 1. Protozoa. 8000 different kinds. a. Rhizopoda. Example, the amoeba. b. Ciliata. Example, the paramoecium. 2. Porifera. Sponges, 2500 different kinds. Example, the bath sponge and grantia. 3. Ccelenterata. Hydra, corals, and jellyfish. 4500 different kinds. a. Hydrozoa. Example, the hydra, obelia, pennaria. b. Scyphozoa. The large jellyfishes. c. Actinozoa. The corals. 4. Echinoderms. Starfishes and sea urchins. 4000 different kinds. 5. Worms and wormlike animals. Examples, flat worms, tape worms, earthworms. 11,000 different kinds. 6. Mollusca. The clams and snails. 61,000 different kinds. a. Pelecypoda. Example, clams. b. Gastropoda. Example, snails. c. Cephalopoda. Example, squids, devilfish. 7. Arthropoda. Crabs and insects. 400,000 different kinds. a. Crustacea. Example, crayfish and crabs. 10,000 different kinds. b. Insecta. Example, grasshopper, flies, butterflies, bees. 390,000 different kinds. II. Vertebrates. Animals with a backbone. 1. Fishes. Examples, trout, perch, bass, cod. 13,000 different kinds. SCIENTIFIC TERMS 7 2. Amphibia. Example, frog, salamander. 14,000 different kinds. 3. Reptilia. Example, snakes, turtles, alligators. 35,000 different kinds. 4. Birds. Example, sparrow, eagle, hawk, crow. 13,000 different kinds. 5. Mammals. Example, horse, cow, sheep, monkey, man. 35,000 different kinds. The plants, like the animals, are arranged in general groups (phyla) which, beginning with the simplest, are as follows : I. Cryptogams. Flowerless or seedless plants. 1. Thallophytes. a. Bacteria. 1300 different kinds. b. Algse. Example, pleuroccocus, spirogyra. 1300 different kinds. c. Fungi. Example, molds, puff-balls, toadstools. 64,400 dif- ferent kinds. 2. Bryophytes. a. Liverworts. 4000 different kinds. b. Mosses. 12,600 different kinds. 3. Pteridophytes. 4500 different kinds of ferns. II. Phanerogams. Flowering or seed-bearing plants. 1. Gymnosperms. Example, pine, spruce. 540 different kinds. 2. Angiosperms. Flowering plants proper. a. Monocotyledons. Example, corn. 23,700 different kinds. b. Dicotyledons. Example, bean. 108,800 different kinds. Scientific Terms. — Scientists in America, France, Ger- many, Russia, and elsewhere are continually studying different plants and animals. For their convenience the Latin names are usually adopted in advanced scientific works. Thus the English or house sparroiv is called .Pasxrr domesticus, and the American elm, Ulmus americana, so that scientists of different countries may always use the same term. But in this book we shall use the common Ameri- can names of the plants and animals studied. Scientific terms include also the names of certain suit- stances frequently referred to in science books like this 8 INTRODUCTION Nitrogen Sulphur Phosphorus Calcium etc Biology. Before going farther it is well to get a clear idea of what the common chemical terms mean. 1. Oxygen is a gas which makes up a large part of the air. It is the element in the air which sustains life in animals and plants. Without it they cannot live. When given an undue amount of it, they develop at an ab- normal rate. It forms about seventy per cent of the bodies of plants and animals. The most striking property of oxygen is the ease with which it unites with other sub- stances. Practically all cases of burning are caused by oxygen unit- ing with paper, wood, coal, or some other material. If a piece of glowing charcoal is placed in a jar of oxygen, it bursts into flame. This is the test for oxygen. 2. Carbon is, next to oxygen, one of the most important elements in biolog}^. It is usually black and solid and is best seen as the charred remains of any material that has been overheated but not burned up, as when toast or meat is " burned." Carbon forms about fourteen per cent of the body of plants and animals. 3. Hydrogen gas is the lightest of all substances. For this reason it is used in balloons and Zeppelins. It forms a little less than ten per cent of the body of plants and animals. 4. Nitrogen is a gas which — unlike oxygen and hydro- gen — does not burn. It dilutes the oxygen of the air and Figure 5. — Diagram. Showing proportion of chemical ele- ments in living things. ORGANIC AND INORGANIC MATTER 9 so makes it less active. Nitrogen forms less than three per cent of the body of plants and animals. 5. Calcium., sulphur, phosphorus, iron, and potassium are the other important elements found in living things. None of these elements forms as much as one per cent of the body of plants or animals. Chemical Compounds. — All these chemical elements com- bine with each other to form definite substances called chemical compounds, which we can see and handle. Oxy- gen and nitrogen mixed together make up about ninety- nine per cent of the atmosphere ; hydrogen and oxygen unite to form water ; carbon, hydrogen, and oxygen unite to form starch and sugar. The union of oxygen with any other substance produces heat or energy. This uniting is called oxidation. When oxygen unites with carbon in our bodies, carbonic acid gas (carbon dioxide) is formed and heat is produced. The production of heat is one of the most important of the changes that take place in living things. Physical and Chemical Change. — If a solid piece of ice is melted, it becomes liquid water. If the liquid water is boiled, it becomes steam, vapor, or gas. If the steam is condensed, it becomes water, which in turn may again be frozen into ice. Any change in a substance which does not alter the material of which it is composed is called a physical change. On the other hand, when oxygen unites with wood, the wood burns, giving off heat and smoke, and asli remains. But this ash cannot be united with heat and smoke to form the original wood. Such a change as is seen in the burn- ing of wood is called a chemical change. Organic and Inorganic Matter. — It is customary to separate chemical compounds which are made in living things from those which are made outside the bodies of plants and 10 INTRODUCTION animals. All matter such as wood, sugar, and meat, which is made in living things, is called organic matter. All matter like stones and water, which is made outside of living things, is called inorganic. Environment. — Plants and animals have accustomed themselves to live in different parts of the world. . Their behavior and habits under these varying conditions form a most interesting part of the study of biology. The sur- roundings of plants and animals, that is, the different con- ditions, the air, water, climate, and soil in which they live, are called their environment. PRACTICAL BIOLOGY PART I ANIMAL BIOLOGY CHAPTER I THE GRASSHOPPER, A REPRESENTATIVE ANIMAL 1. Live Animals. — We all know that animals are alive, just as men and plants are alive, and we naturally want to know how they live, what parts of their bodies they use in eating and breathing, and how they escape their enemies. After we have learned about the lower animals, we can compare them with plants and with man, and it will be interesting to learn in what ways all living things are alike. When the study of Biology begins with ani- mals, all that is necessary is to select an animal that can be conveniently found and watched ; and then to try to learn where it lives, what it does, how it produces its young, and what relation it has to mankind. Material for study is easily obtained wherever you happen to live, whether in the city, the country town, or on the prairies. A nearby park or vacant lot, the fields, the woods, or the plains, u Figure 6. — Female Grasshopper. 12 THE GRASSHOPPER whichever you can reach most easily, will supply you with a collection of insects, if you look carefully. All insects will be found doing something. Some will be flying from flower to flower, and you can watch to see what they are doing; others will be busy on the leaves or the stems, and a few minutes of observation will show you whether they are friends or foes of the plant upon which you find them. The most interesting way to study in- sects is to watch them in their home life, but when this cannot be done, they can be well studied in the laboratory. Even in a large city a surprisingly large number of kinds of insects can be collected by a class and brought alive to the laboratory. 2. The Grasshopper. — The study of animals begins in this book with the grasshopper. When during the late summer we walk into the fields or along paths lined with grass, we are often surprised at the number of grasshop- pers which jump away as we approach. They are of va- rious sizes and kinds. Some are small and without wings, while others have small but well-formed wings. The difference in the wings and in the shape of the body tells us that there are various kinds of grasshoppers. FIELD STUDY To study living insects. Collect insects such as grasshoppers, crickets, beetles, bees, wasps, flies, moths, butterflies, etc. Place some under tumblers and complete your report as follows : o 32 05 0 W Mouth Parts Where Found H a x - 5 6 — f. - C ~. Z. Size oi Wings Size oi Third p T3 CD CD 3 House fly . On food in the home 2 Small Grasshopper On grass in the field 6 4 Medium Moth . . On flowers in the park 6 4 Large LIFE PROCESSES 13 3. Life Processes of the Grasshopper. — The young grass- hopper must escape being eaten, must find food, must have oxygen to breathe, must develop into an adult, and must do its part in providing for another generation of grass- hoppers. If the grasshopper fails in any one of the first three of these necessities, it is unable to live, and conse- quently the last and most important work, that of provid- ing for the next generation, is not possible. LABORATORY STUDY Examine a live grasshopper. What are its means of locomotion ? Compare its jump with its length. If in the same proportion, how far could a man six feet tall jump ? How does the grasshopper obtain food ? What protection from enemies does it gain from its color ? Notice the divi- sion of the body into three regions ; head, thorax (tho'raks) which has wings, and abdomen (ab-do'men). When the living grasshopper is held between the thumb and finger, it " spits molasses." This is the partially digested food from its crop. 4. Protection — When we look closely at the grass- hopper, we find that it is provided with many character- N>7U.'oU!. J/bdomen PntT.-rax Figure 7. — Diagram. Showing the main parts of the grasshopper. istics which prevent its being caught and eaten. The most important of these are its color and markings. When a grasshopper jumps into the grass and remains 14 THE GRASSHOPPER ibru abrum ndibU mandible ndiblf mandible '.;) nupo pharynx quiet, its color so closely resembles the grass and the sticks that many of its enemies overlook it. This is an example of what is called protective coloration. The grass- hopper is further protected by a pair of large eyes and by simple ears which are located on the side of the body. By means of these sense organs, it becomes aware of the presence of enemies. The quickness of grasshoppers in jumping also helps them to escape being eaten. 5. Food Getting. — The grasshopper has little difficulty in finding its food. It eats leaves, and particularly the leaves of grass. It does not need a keen sense of smell, as does the bee which must search for flowers. However, the grasshopper has special smelling organs located in its antennas (£n- ten'e), those long feelers which grow out from the head like soft horns. The mouth parts which cut and chew the food consist of an upper lip and two teeth (mandibles, man'di-b'ls). The teeth are moved by powerful muscles which nearly fill the head. These mandibles work from side to side, instead of up and down as our teeth do. They are so effective that sometimes when grasshoppers become numerous they strip the grass of all its leaves, and even destroy growing fields of grain. 6. Breathing. — All animals have some way of getting oxygen to every portion of their bodies and of getting rid of carbon dioxide. The grasshopper has no lungs such as ( in maxilla maxi ila biu a bium Figure 8. — Mouth Parts of the Grasshopper. LIFE HISTORY 15 ours, nor does it breathe through its mouth. On each side of the body are found a number of regularly arranged, small openings, spiracles (spir'a-k'ls), which lead into * branching tubes, traehece (tra/ke-e). These tubes carry air to all parts of the body in order that the cells may be able to take the oxygen from the air and give carbon dioxide to it. The cell process in which oxygen is used and carbon dioxide formed is called respiration. See section 6, page 3. 7. Reproduction and Life History. — In the autumn, the female grasshopper lays her eggs in a hole which she makes in the ground. The eggs remain in the hole until the following spring, when they hatch into wingless grasshop- pers. Their bodies are covered by a firm skin, called the exoskeleton, which does not increase in size as the grasshop- pers grow, so this skin must be shed to allow room for growth. Young grasshoppers, like young children, grow rapidly; therefore the grasshoppers have to shed their skeleton often and grow a new and larger one. The scientific term for this shedding of the old skeleton and the growing of a new is molt (molt). In the early spring and summer, the young grasshopper molts again and again, each time growing a little more like the adult grasshopper. This process of growth takes three or four months. After the last molt, it has wings and can fly, and so is a full-grown grasshopper. Figure 9. a, Grasshopper laying Eggs ; b. Egg- capsule ; c, Eggs. 16 THE GRASSHOPPER LABORATORY STUDY Work out the divisions of the body of the grasshopper : head, thorax, and abdomen; the position of eyes. How are the antennae related to the eyes ? How many distinct mouth parts are there ? The teeth or jaws are the most useful in getting food. How do the jaws work ? Sketch the head to show these parts with the mouth open. Notice the attachment of the head to the thorax. The head fits into the thorax. The loose anterior (front) portion of the thorax is the pro- thorax (forward thorax). The first pair of legs is attached to it. Sketch the prothorax to show it and its legs. The portion of the thorax back of the prothorax is divided into two regions: the mesothorax (middle thorax) and the metathorax (back thorax). The line between them is not clear. Sketch these parts together with the legs and the wings. The jumping legs are attached to the metathorax ; the outer wings to the mesothorax ; the inner wings to the metathorax. The inner wings are used in flying. The leg of the grasshopper consists of : (1) a small section close to the body (the coxa) ; a long muscular part free from spines (femur) ; a slender spiny part (tibia) ; and the three segments of the foot (tarsus) . The last segment of the foot is furnished with hooks which help the grasshopper in climbing, while the spines on the tibia pre- vent slipping as the grasshopper jumps. The large muscles in the femur of the last pair of legs, the spines on the tibia, and the hooks on the tarsus, are special adaptations which help the grasshopper in various ways. Notice the tapering abdomen, composed of ten segments (rings) or parts of segments. Notice the depression and membrane in the first segment. This is the auditory organ, but it is not a true ear. Sketch the abdomen to show its features. The spiracles are located on the sides of the abdomen. 8. Metamorphosis. — All animals which pass through a marked change in external appearance as they become full grown are said to undergo a metamorphosis (met-a-m6V- fo-sis : Greek, meta, change; morphe, form). These changes are more marked in such insects as the ants and bees than in the grasshopper. For this reason we speak of two forms of metamorphosis — complete and incomplete. 9. Incomplete Metamorphosis. — The newly hatched grass- hopper, while very small, looks enough like a wingless grasshopper to be identified as belonging to the grass- COMPLETE METAMORPHOSIS 17 hopper family. Its form does not change materi- ally from the time it is hatched until it is full sized. Thus the grass- hoppers become adult by a growing process termed incomplete meta- morphosis, showing no marked change in form (Figure 10). 10. Complete Metamor- phosis. — Certain other insects, for example the codling moth, hatch into caterpillars from the eggs that the female lays in the apple. These caterpillars are known as larvae (dar've : Latin, larva, mask). The larvae of the codling moth are the " worms in the apple." These larvae are not recog- nized from their external appearance as young codling — - Figure 10. — Incomplete Metamor- phosis of the Tree Cricket. The tree cricket belongs to the same family of insects as the grasshopper. Figure 11. — Codling Moth Larva. 18 THE GRASSHOPPER moths, yet that is what they are. As the larva eats a great deal, it grows rapidly, molting again and again until it becomes a full-sfrown cater- pillar. It then eats its way out of the apple where it has been living its lar- val life for several weeks. In some pro- tected spot, under the bark scales, the full-grown „, „ caterpillar then Figure 12. — "The Worm in the Apple.' l weaves a silken covering (the cocoon, ko-koon/) about itself. In this cocoon it molts again. When this last molt occurs, the Figure 13. — Codling Moth Pupa. caterpillar loses its legs and mouth parts, and is now known as a pupa (pu'pa). The pupa does not eat, but STRUCTURE 19 continues to breathe. Thus we speak of this stage in the growth of the codling moth as the "resting stage" This resting stage of the codling moth pupa l is very short. Then a linal molt takes place and the fully formed codling moth crawls from the cocoon (Figures 11-14). This series of changes through which the cod- ling moth passes from egg into caterpillar, FlGURE 14._CoDLING MoTH. then into pupa, and finally into full-grown moth, is termed complete meta- morphosis. Ants, bees, butterflies, beetles, and certain other insects, all undergo complete metamorphosis. There are a number of different terms used to describe the larval stage of insects : caterpillars are the larvae of butterflies and moths. grubs are the larvae of beetles. " wigglers ' ' are the larvae of mosquitoes. maggots are the larvae of flies. currant worms are caterpillars. measuring worms are caterpillars. 11. Structure and Classification of the Grasshopper. — In order to understand the grasshopper more fully it is necessary to find its place in the classification of animals. All animals that are known have been grouped into classes for convenience in study. The grasshopper belongs to the large class of animals called Insecta (In-sek'ta : Latin, in, in; seco, cut). The insects, as a class, have their bodies divided into Larvae 1 Sometimes the codling moth passes into the pupa stage in the fall, thus living through the winter in the " resting stage." 20 THE GRASSHOPPER three regions — head, thorax, and abdomen. See Figure 7. All have three pairs of legs, and most of them two pairs of wings. . They breathe by means of air tubes (tracheae'). In becoming adult, all pass through metamorphosis, either complete or incomplete. The insect group is subdivided into ten smaller groups or orders. The grasshopper belongs to the order known as Orthop- tera1 (6r-thop'ter-a : Greek, orthos, straight; pteron, wing). In the Orthoptera we find six common families : grasshop- jDers, crickets, katydids, cock- roaches, walking sticks, and praying mantids. 12. Economic Insects. — By economic insects, we mean those insects which, by their activities, are either helpful or harmful to man. If an insect has no economic impor- tance, we mean that it does not harm us by eating things useful to us, nor does it help us in any way. The struggle to live is a problem for all animals, for Figure 15. — Monarch Butterfly. Showing how it carries pollen from one clover blossom to another. 1 grasshoppers, katydids, crickets butterflies and motbs beetles bugs bees, wasps, ichneumons, gall flies flies and mosquitoes dragon flies May flies stone flies fleas (straight wings) (scaly wings) (shield wings) (half wings) (membrane wings) (two wings) (teeth) (short lived) (net wings) (wingless) often called siphon-mouthed Orthoptera Lepidoptera Coleoptera Hemiptera Hymenoptera Diptera Odonata Ephemeridae Plecoptera Aptera Siphonaptera ECONOMIC INSECTS 21 man as well as for the grasshopper. All insects must eat, and some eat the same things we wish to eat. Such in- sects we call harmful. Others aid the growth of plants by carrying the pollen dust from one flower to another ; Figure 16. — Modern Spraying Outfit. Used to destroy harmful insects. others make honey. Such insects are useful. Certain other insects, like the fly, carry the germs of disease. These insects are particularly harmful, for they cause sickness and death. 22 THE GRASSHOPPER Certain beetles eat dead flesh or bury dead animals by tunneling under them. Such insects are helpful. We should study insects in order to find out which are our friends and which our enemies. It would not do to kill all kinds of insects, for in many cases we should harm ourselves. 13. Economic Phases of the Grasshopper. — The grasshopper eats the leaves of plants, and if there are many grass- hoppers, they cause a serious loss of crops. The plague of locusts mentioned in the Bible refers to grasshoppers. In some of the Western States years ago the grasshoppers came in great swarms year after year and destroyed annually crops estimated to be worth 1200,000,000. But ordinarily, owing to the activities of their natural enemies, the number of grasshoppers does not become alarming. Among the natural enemies of these insects that do much toward reducing their number are the birds. Some of the greatest destroyers of grasshoppers are the quail, blue- bird, sparrow hawk, butcher bird, crow, red-winged blackbird, and kingbird. The crows, because of their large size and great numbers, probably kill the most grasshoppers. Other members of the order of Orthoptera, that are more or less harmful, are the cockroaches, the nuisances of the pantry, and the crickets that eat the roots of plants. There are also tree crickets which frequently lay their eggs in raspberry cane and kill the cane above the place where the egg is laid. 14. What has an Animal like the Grasshopper Accomplished by Living? — (1) It has used plants as food to build a complex body. (2) It has produced more grasshoppers. (3) It has used some stored-up food which might have been useful to cattle or sheep. (4) It has set free waste QUESTIONS 23 carbon dioxide which can be used by green plants to assist them in making food. (5) When it dies and decomposes, its chemical substances are returned to the soil and air to be used again by other living things. QUESTIONS What are the most important things that the grasshopper must do to live ? How is the grasshopper protected ? How does the grasshopper breathe? How get its food ? How does the grasshopper begin life ? Define metamorphosis. How many kinds of metamorphosis are there? Which kind does the grasshopper show ? Is the grasshopper a friend or an enemy to man ? Why ? *$0&* CHAPTER II OTHEE COMMON INSECTS In the preceding chapter we studied the grasshopper, a typical member of the Orthoptera. We shall now take up several other orders of insects, with most of which we are already familiar. 15. Hemiptera. — Another common order of insects is the Hemiptera (he-mip'ter-a: Greek, hemi, half; pteron, Figure 17. — Scale Insects on Fern. wing). To this order belong such common insects as the cicadas, plant lice, the woolly aphis, and the bane of the orchard, the San Jose (san ho-sa') scale. Some of these are very harmful. When the San Jose scale is allowed to feed freely, whole orchards may be destroyed. Plant lice injure apple, cherry, and peach trees, and the 24 CICADA 25 Figure 18. — Mealy Bug. One of the scale insects. cabbage plant. The several kinds of scale insects which harm orchards may be killed by spraying the trees with a solution of lime and sulphur. 16. Cicada. — One of the most interesting insects of the Hemiptera is the seventeen year cicada (si-ka/da), com- monly called the " seventeen year locust." The name is given to it because the nymphs (nim'fs, the imma- ture stage) remain in the ground, actively feeding on roots, for seventeen years. There is another kind of cicada that remains in the ground for thirteen years. Every thirteen or seven- teen years, generally in the month of May, the nymphs crawl out of the ground, climb trees or fences, and molt into adult cicadas. The adult females lay their eggs in tender shoots of trees, and this causes the shoots to die. The young cicadas, after hatch- ing in the shoot of the tree, go into the ground and begin their long period of larval exist- ence which lasts thirteen or seventeen years. These cicadas are usu- ally found in limited areas, but in these areas Figure 19. -Cicada, Adult and Nymph. are very numerous. The cicadas which we hear every summer are another kind, whose nymph lives in the ground for two years. As there are two broods 26 OTHER COMMON INSECTS of this species that appear in alternate years, the number does not seem to vary from year to year. The birds do much towards destroying them. The kingbird, sparrow hawk, butcher bird, and great-crested flycatcher are their most common enemies. 17. Coleoptera. — The Coleoptera (co-le-op'- ter-a : Greek coleos, shield ; pteron, wing) are the beetles. The first pair of wings is horny and meets in a The second pair of wings The mouth parts are for Figure 20. — May Beetle. Note difference in first and second pairs of wings. straight line down the back, consists of thin membranes, biting. Among the harmful beetles are many wood borers, the May beetles, potato beetles, asparagus beetles, and weevils. Some of the beneficial beetles are the ladybug, which feeds on destruc- tive and harmful insects, and the carrion beetle, that feeds on dead animals. The ladybugs are decidedly beneficial. Their larvae run over leaves and feed on other insects. Even as adults they continue this good work. Hop growers appreciate the value of the ladybug larvae on their vines, as the ladybugs destroy the harmful hop lice. Figure 21. — Eggs of Ladybug. LEPIDOPTERA 27 Through the investigations of the United States I)e- partment of Agriculture a certain kind of ladybug (Vedalia) was found in Australia, which is the natural enemy of an insect pest (cottony cushion scale) that was destroying the orange trees grown in California. This scale is a plant insect which was imported into the I nited States on young trees. Being1 freed from their natural enemies (Ve- dalia) which were not imported, they had in- creased rapidly. The prompt importation of Vedalia put an end to their increase, and tliey are now of no great economic importance. The bird enemies of the beetle are numerous. Among the most impor- tant are the ring-necked pheasant recently intro- duced, the rose-breasted grosbeak, and the quail, which feed particularly on the potato beetles. The English sparrow, cuckoo, and kingbird feed on the weevils. Robins, blackbirds, and crows eat the white grubs, the larval stage of the May beetles. The wood- peckers destroy great numbers of borers by digging holes in the trees where the borers are tunneling. 18. Lepidoptera. — The Lepidoptera (lep-i-dfy/ter-a : Greek, lepidas, scaly ; pteron, wing) include the familiar moths and butterflies. Some of the members of this order, Figure 22. Holes made by Wood- peckers. 28 OTHER COMMON INSECTS Figure 23. -Redheaded Wood- pecker. such as the adult peach-tree borer, look more like wasps than like moths. There are more harmful insects in the Lepidoptera than in any other order. Among the particularly destructive members are the insects which are commonly called codling moths, gypsy moths, brown tail moths, tent caterpillars, cut-worms, army worms, and canker worms. But not all the Lepidoptera * the most beautiful moths and are harmful. Many of butterflies develop from larvae that do no particular harm. Their natural enemies, such as birds and ichneumons (see section 21, page 39), keep their numbers reduced. Among the more strikingly colored butterflies are the black swallow- tail, the larvse of which feed on celery, parsley, and carrots ; and the monarch or milkweed butter- fly- LABORATORY STUDY The adult monarch butterfly has the body divided into head, thorax, and ab- domen. The legs are smaller than in the grasshopper, while the wings are larger. The butterfly is, therefore, poorly adapted for jumping, but better adapted for flying than the grasshopper. Draw the entire animal. Draw wings and legs. Gently rub the finger on the wing, and as the dust comes off, the wing Figure 24. — Larva of Mourning Cloak Moth. Gradually transforming into a pupa. The cast-off skeletons of the larva appear in the middle row. 1 The Chinese silkworm is a valuable member of this order. LEPIDOPTERA 29 will look more like the wing of a fly or bee. The lines that run length- wise of the wing are the veins. Draw the winu. The mouth parts of the butterfly are united into a single long tube which is the coiled tongue-like structure, called the proboscis (pro-bos' is). Unroll it and see how its length compares with the length of the body. The butterfly uses the proboscis to suck nectar from flowers. Figure 25. — Transformation of Pupa of Mourning Cloak Butterfly into Adult. 30 OTHER COMMON INSECTS As the butterfly goes from flower to flower after nectar, its head brushes against the parts of the flower that grow the pollen dust. The pollen is thus carried from one flower to another, and this helps the flower to grow better seeds. Enemies of the Lepidojotera. — The numerous enemies of the Lepidoptera prevent them from becoming a scourge. Chief among these enemies are the ichneumons, members of the order Hymenoptera (Figure 40). Ichneumon- (lk-nu'mon) adults lay their eggs on the bodies of many caterpillars. When these eggs hatch into Figure 26. — Cecropia Moth. Larva, pupa, cocoon, and adult. Figure 27. — Young Tobacco Worm. Bearing cocoons of parasite. small larvae ichneumons, the larvse eat their way into the body of the large caterpillar, where they live feeding upon its body juices. These ichneumon larvse are called para- Charles Robert Darwin (1809-1882). the celebrated English naturalist, was the founder of the Darwinian theory of evolution. After taking part in the scientific expedition of the Beagle around the world, Darwin settled in 1842 in the secluded village of Down in Kent, where he devoted himself to a life of study and scien- tific research. In 1859 he published his chief work. "The Origin of Species," which was translated into many languages and be- came the subject of more discussion than any volume of the age. A second great work, "The Descent of Man," appeared in 1871. and Darwin continued to produce important scientific works throughout his life. LEPIDOPTERA 31 sites because they derive their food from the caterpillar. The caterpillar which contains these ichneumon parasites is called a host. The ichneumon parasitic larva3 grow rapidly and before the caterpillar dies they reach the stage at which they turn into pupse. When they are ready to pupate, they eat their way out of the body 3f the caterpillar and spin a cocoon which in some cases remains at- tached to the body of the 3aterpillar (Figure 27). These parasitic larvae so veaken the caterpillar :hat it dies. We shall earn more of these ich- leumons later. Next to ichneumons, she birds are probably :lie most active enemies >f the Lepidoptera. Many birds live entirely ipon caterpillars and we ind birds that seek them as food in all stages of their levelopment and growth. The eggs laid on the twigs md trunks of trees are eaten by chickadees, nuthatches, Drown creepers, and woodpeckers. The larva' are eaten 3y many birds, notably by cuckoos, bluebirds, wrens. blackbirds, orioles, blue jays, crows, and house sparrows. The cocoons and pupae are sought by the chickadees, woodpeckers, nuthatches, and brown creepers. The adult nsects are preyed upon by house sparrows, chipping sparrows, and the whole group of flycatchers, including :he kingbirds and phoebes. Figure 28. — Larwe of a Leaf Miner. At work in an elm leaf. 32 OTHER COMMON INSECTS 19. Codling Moth. — The most destructive of the lepidopterous insects is the codling moth, already men- tioned as an example of metamorphosis. The larvre become adult in April at about the time the early apple trees blossom. The eggs are laid on the young apples and the larvse begin to eat the growing apple, which, as a result, in many cases drops to the ground. In any event the quality of the apple is injured. In most parts of our country, there are two distinct broods of the codling moth, the life history of which has only recently been clearly understood. The eggs of the second brood are laid generally in August when the fruit is pretty well grown. The same damage is done as to the early apples, but as each mature female lays a hundred or more eggs and as the most important apple crop is the late one, the chief damage is at this time. Figure 30. — A Geometrid Moth. Figure 29. — Cedar Bird. Feeding its young a flying insect. One of our most beneficial birds. CODLING MOTH 33 It was estimated that in 1898 the injury done by the codling moth to the apple and pear in- dustry in New York State alone amounted to $3,000,000. By apply- ing a spray containing some poison just after the blossoms have fallen, the codling moths may be destroyed. The spray should not be used while the blossoms are fresh, because then the help- ful bees which visit them are killed, and no harm is done to the destructive codling moths that come later.1 Figure 31. — Protective Coloration. Figure 32. — Yellow Swallowtail. Gathering honey from lilacs. FIELD, LABORATORY, OR HOME STUDY OF MOTH S AND BUTTERFLIES These insects are easily collected and are interesting to study. From late in the spring until October you can find lame and pupa?. Some of the leaves upon which the larvae are feeding should be collected. The larva1 should be placed in jars provided with soil and some leaves. Arrange the cocoons and pupa? which you find as suggested in tin- following table. 1 The life history of the peach-tree borer and monarch butterfly may be assigned in this connection. 34 OTHER COMMON INSECTS Cocoon Pupa Spun with silk only Spun with a leaf Spun with hair Without cocoon Suspended from one end Suspended from one loop Parasit- ized Tent caterpillars spin cocoons and form small brown moths. Celery "worms" hang in a loop and form a black, swallowtail butterfly which feeds on the nectar of lilacs and the rhododendrons of city parks. The black spiny caterpillars of the willows and elms hang free from the knot of silk and form the mourning cloak butterfly. Tomato "worms" burrow into the ground and form a large-bodied, small-winged moth, a sphinx moth. 20. Hymenoptera — The Honeybee. — In contrast to the Lepidoptera, which, as has been said, are probably the most ****» 6 Figure 33. — a, Honey Bee Worker ; b, Queen ; c, Drone. Twice natural size. destructive order, we find the Hymenoptera (hy-men-op'- ter-a: Greek, hymenos, membrane or thin skin; pteron, wing) that are of the greatest value to man. This order includes the bees, wasps, ants, ichneumons, and the like. HYMENOPTERA — THE HONEYBEE 35 Figure 34. — 1 href. Queen Cells. Natural size. The honeybee and the bumble bee are the most important of the bees. The honeybee is valuable for its honey and wax, and as a distributor of the pollen which is necessary for the growth of new plants. The bumble bee is valuable mainly as a distributor of pollen. Honeybees afford a splendid example of community life among insects. In the wild state they live in trees and caves. All wild honeybees in this country have escaped from hives or apiaries (bee farms). In a honeybee colony there are three classes of bees, — the perfect females or queens, the males or drones, and the imperfect females, or workers. There are generally one queen, a few hundred drones, and twen- ty to fifty thousand workers. The queen alone can lay eggs. She can lay an unfer- tilized egg which hatches into a drone, or she can lay an egg which is fertilized. This fer- tilized egg hatches into a queen or a worker, according to the food and the size of the cell which are provided by the workers. Thus the decision as to whether the young bee shall be a queen or a worker rests with the workers themselves. They also have t lie power to supersede the queen, or to raise a new queen Figure 35. — a, Honey Bee Egg; b, Young Larva; c, Old Larva ; d, Pupa. Three times natural size. 36 OTHER COMMON INSECTS in case of the sudden death of the old one. These powers are rightly intrusted to the workers — the great majority. The eggs are placed by the queen in cells, and, after hatching, are fed by the young workers, called nurses. The larva is fairly bathed in food. In a few days the larva is full grown, and then pupates. The workers now cap over the cell with wax, and in about twenty-one days the young bee cuts away the cap and crawls out — an adult provided with four wings, mouth parts, antennae, and the six legs of the honeybee. Workers are provided with the sting which is a weapon of both defense and offense. The queen has a small sting, and the drones have none. When bees sting large animals, like men, horses, and dogs, their sting is pulled out and with it parts of the internal or- gans, thus causing the death of the bee. When bees sting other insects, or even one another, their sting is not lost. Sometimes swarms which have few bees and little honey are attacked by bees from other colonies. It is a pitched battle until the " robber bees " are beaten back, or the de- fenders are themselves killed. The sting is used in these battles. Figure 36. — Honey Bees Clustering at Swarming Time. HYMENOPTERA — THE HONEYBEE 37 Bees are instinctively sanitary. If a large bumble bee enters the hive, the bees kill the intruder and usually, finding him too large to be taken out, embalm him by in- jecting the sting repeatedly into his body. The result of this operation is to make the bumble bee harmless to the colony. Some- times they cover the body of a small, dead animal with a case made of propolis (prop'6-lis), a substance the bees gather from certain buds. This serves to protect the colony from the effects of the decom- position of the body. At irregular intervals during the ea/ly spring and summer, bees have the peculiar habit of swarming. Several rea- sons for swarming are given by bee-keepers, but no one pretends to be certain that he really knows the cause. It is a sort of revolt of the bees against their condition. Two of the commonest reasons given to explain swarming are the lack of room for the growing colony, and lack of food. When bees swarm, they usually light on the limb of a tree and form a dense cluster. Here they hang from fifteen minutes to an hour before leaving for the woods. In a few cases bees have remained in this "cluster" state Figure 37. — Capturing a Swarm. 38 OTHER COMMON INSECTS overnight, but usually they are lost unless they are col- lected inside of half an hour. The swarm consists of a large number of adult bees, workers and drones, and usually a single queen. Various devices against swarming have been invented, but the most effective is to clip the wings of the queen in order that she may be kept at home, because the other Figure 38. — Model Apiary. bees usually follow her. This is done after the queen has taken her " wedding-flight." Her wings are clipped close to the body, but only on one side. The bees that then swarm soon come back and are easily controlled. While the bees are still in the air, a clean, empty hive is placed where the old one was. Beekeepers, during the swarm- ing period, always have a number of empty hives in position ready for the swarm to occupy. The returning bees enter the new hive in search of the queen. As they are rushing in, the queen with clipped HYMENOPTERA — THE HONEYBEE 39 wings is released, and she, in turn, joins the procession and enters with the others. Having found the queen and plenty of room, the colony is usually content to remain. Sometimes swarming becomes a mania with certain colonics, and it is difficult to get them to settle down contentedly in a hive and make honey. Runaway swarms have to be watched with great patience. Bees that have been raised for many bee generations in man-made hives sometimes leave suddenly and seek out a hollow tree in the forests. The length of the bee's life varies. The drones are usually killed at the end of their first season. Queens live for five or six or even ten years. Workers live three or four weeks in the working season and several months in the fall or winter. The honey and wax produced annually in the United States are valued at 122,000,000. 21. Ichneumons. — Another interesting division of the Hymenoptera are the ichneumons. We have already seen (page 30) how they help to keep the Lepidoptera from be- coming a scourge. They also furnish other interesting ex- amples of parasitism. As an illustration Ave may use one of the larger ones known as Tfialessa. With long, thread- like drills this parasitic insect bores holes in trees, and lavs an egg at the bottom of the hole. The egg is usually laid near the burrow of one of the larger tree borers, the Tremex* Figure 39. — Cutting Combs from Box Hive. 40 OTHER COMMON INSECTS The larva of the Thalessa makes its way along the burrow of the Tremex borer and fas- tens itself to the body of the borer, where it feeds upon the borer and thus kills it. In time the adult Thalessa emerges, ready in turn to do its part in laying eggs which will destroy more of these enemies of the tree. But if the Thalessa parasites kill the Tremex borer before it has eaten Figure 40. — Ichneumon Flies. ., ,-, ■, . , * n its way through the hard Laying eggs in a tree. , . n ,. wood, then all die to- gether, because the Thalessa cannot cut an opening for itself. Figure 41. — Adult Horn-tailed Saw-fly. Just after laying eggs in a tree. The larvae of this insect do much damage to lumber. DIPTERA 41 22. Ants. — The ants are insects which live in large families. Each family has many workers, and a number of queens and males. Certain kinds have in addition their soldiers which have strong mouth parts (mandibles). The soldiers do the fighting for the family. Some ants are winged and others are wingless. Many ants have the curious habit of protecting the plant lice, because these lice give off a sweet fluid of which the ants are fond. In some cases the ants carry the plant lice from the wilted leaf to a fresh one, or confine them in the ants' nest and bring them fresh leaves. When they wish to feed on the sweet fluid, the ants quietly stroke the body of the plant lice with their antennae. 23. Diptera. — The Diptera (dip'ter-a: Greek, dia, two; pteron, wing) include such harmful insects as the mos- quito, housefly, botfly, and cheese skipper ; also the bene- ficial bee fly, wasp fly, and tachina fly. The most important member of this group is the mosquito. The common mosquito lays its eggs in the water in small clus- ters which look like minute rafts. These eggs hatch into larvse, called " wigglers. " Any stagnant pool or rainwater bar- rel furnishes a favorable place for mosquitoes to breed. In the United States there are three distinct kinds of mosquitoes. (1) The common mosquito is known by the technical name of Culex (kiVleks). It is not known that the Culex carries in its body any disease germs harmful to men, therefore it is regarded as harmless, although a source of great annoyance to those who frequent the woods Figure 42. — Fly. 42 OTHER COMMON INSECTS a I - - * ' ' ■!, It if ft \a>. 3;- - Figure 43. — Eggs and Larwe of CULEX. The commonest mosquito. or seashore during the summer. (2) Anopheles (a-nof7 e-lez) is the scien- tific name of a second kind of mosquito, which is also generally distrib- uted, but is not so numerous as the Culex. The Anopheles often carries in its body the germs that cause the disease called malaria. (3) Stegomyia (steg-o-mi'ya) is a mosquito common in the southern part of the United States. It is the insect which carries the germs of yellow fever from one person to another. It is fortunate that the mosqui- toes have so many enemies. The " wigglers " are preyed upon by the larvas of the dragon flies, by small fish, and by water beetles; while the adults are eaten by nighthawks, martins, bats, and dragon flies. Certain diseases caused by plants attack the adults and kill them in great numbers. The number of mosquitoes can be greatly reduced by destrojdng their natural breeding places in old rain barrels, watering troughs, boxes that may hold water, pails, eaves troughs, and sink holes. The larger breeding places are sluggish streams and swamps. Draining these is the most effective Figure 44. — a, Adult Culex ; b, Adult Anopheles. SUMMARY 43 method of preventing mosquitoes from laying their eggs in that locality. When this is not possible, the surface of the water may be covered with kerosene, which kills the larvce by preventing them from getting oxygen from the air. Frequent applications of oil greatly reduce the number of mosquitoes. SUMMARY The insects include a large number of animals, the smallest of which can be seen only through a microscope, while the largest, certain butterflies, measure nine inches across their wings. S.ome insects are parasitic and lead dependent lives. Insects feeding on plants which we wish to eat are called harmful. Others, like the honey- bees and silkworms, which make products that we use, are beneficial. Insects such as ticks and lice, that injure our domestic animals, are called harmful. Then there are the beautifully colored moths and butterflies whose larvre never become numerous enough to do much damage ; we say that they are beneficial because we get pleasure from their beauty. The whole question of what is beneficial or harmful depends on the relation of the insect to man. Insects living on an uninhabited island could not be thus classi- fied. In the earlier stages of our civilization, many insects now regarded as harmful were not so classified, because man had not learned to use the plants upon which they fed. The important relation which insects bear to disease has, in recent years, caused us to classify several insects as harmful which were not so considered earlier. Insects, like man, are constantly undergoing a struggle to escape their enemies and to secure food and a place to live. It is interesting in this biological study to try to view ourselves in the same unprejudiced way in which 44 OTHER COMMON INSECTS we study the lower animals ; it helps us better to under- stand ourselves, and to go forth better equipped to wage our contest and win our fight. QUESTIONS Explain the difference between beneficial and injurious insects. Which are some of our most beneficial insects ? How do they help us? How did they help to save the orange industry of California ? How do fruit growers spray their trees ? Why ? What can you do to prevent harmful insects from spreading ? KEFERENCES Crary, Field Zoology, Chapter X. Folsom, Entomology with Reference to Its Biological and Economic Aspects. Hegner, Introduction to Zoology, Chapter XII. Hodge, Nature Study and Life, Chapter X. Kellogg, Animals and Man, Chapter XV. Osborne, Economic Zoology, Chapter XII. Root, A. B. C. and X. Y. Z. of Bee Culture. Smith, Our Insect Friends and Enemies. CHAPTER III THE SIMPLEST ANIMALS — PROTOZOA 24. Definitions. — In our study of the grasshopper and its insect relatives we considered their behavior and life processes. If we had studied the minute structure of any of these insects, the grasshopper, for example, and had used a microscope to aid us, we should have found that every organ was made up of numerous small parts joined together in a definite manner. These small parts are called cells. Any book on biology uses the word cell again and again. The name was first used by Robert Hooke over two hun- dred years ago, when, with his crude microscope, he examined a piece of bark and found it to be made up of little rooms which looked like the cells of the honey com I). These spaces he named cells. When better microscopes were made, the living parts of the cell were discovered, and it was found that Hooke had seen only the walls of dead cells. All plants and animals are composed of cells. A cell may exist alone, carrying on all the life processes itself, or it may exist in connection with a great many other cells, as in all large animals and plants. In every case each cell is produced from another cell. There are certain animals that are never more than one- celled even when they are full grown. These animals are called Protozoa (pro-to-zd'a: Greek, protos, first; zoon, animal). 45 46 THE SIMPLEST ANIMALS — PROTOZOA 25. The Protozoan Cell. — The protozoan cell is a single mass of living matter, called protoplasm. In a general way it carries on the same life processes as the grasshopper; or any other animal. When this living cell comes in con- tact with heat, cold, electricity, chemicals, or other stimuli, it moves, and we say that it is irritable. The term irrita- bility, used with a scientific meaning, is defined as the power of being aware of a stimulus. When this living cell is brought into contact with cold, for example, it makes a definite movement. It is aware of the cold stimulus. The . living cell grows by using food. It takes in oxy- gen from the water or from the air, according to where it happens to live. It gives off waste substances. It can grow or reproduce other cells of the same kind. Many protozoan cells have no limiting wall between the living substance and the water in which they live. Yet the protoplasm and the water do not mix, though we do not understand why. Other Protozoa living in the ocean are surrounded by extremely thin skeletons of lime, and when the animals die their skeletons sink to the bot- tom and become massed in a sort of rock. The famous chalk cliffs of England were formed in this way. 26. Habitat. — The habitat of any animal is the place where it lives. The Protozoa are small, usually micro- scopic, animals common in stagnant pools and in swamp water. They are also common in salt water. In fact, Protozoa are likely to be found in nearly all ponds of water that contain food for them. Often, in the summer time, our attention is called to the activities of Protozoa when the water from lakes or reservoirs has a fishy taste. This peculiar taste may be due either to animals or plants, or to both. When it is due to animals, it is caused by a disagreeable oil formed by a certain kind of Protozoa. By far the greater number of Protozoa are harmless, STRUCTURE OF AMCEBA 47 and many arte helpful to us in that they serve as food for fishes. Others, however, may become parasitic in our bodies, and thus cause such diseases as malaria, yellow fever, or sleeping sickness. 27. Amoeba. — The name amoeba (a-me'ba) is given to several different Protozoa, but all of them represent the simplest form of life known to us. For this reason they are always studied in biology. In order to describe cor- rectly the structure of even so simple an animal as the amoeba a few new words are necessary. 28. Structure of Amoeba. — It is difficult for inexperienced students to see the living amceba through the microscope, because the whole cell has a faint, grayish ap- pearance, and in a strong light is transparent. But if this grayish ap- pearance of protoplasm is once seen, it is always remembered. The living amoeba is continually changing shape and pushing out from the surface of its body blunt, finger-like projections of the proto- plasm called pseudopodia (su-do-po'dl-a: Greek, pseudo, false; pod, root of pons. foot), which give an irregular outline to the body (Figure 45). Sometimes the pseudopodia branch out, and there- fore the scientific name Rhizopoda (ri-zop'o-da: Greek, rhizos, root; pod, root of pous, foot) is the technical name for all amoeba-like Protozoa. The amoeba sends out a pseudopodium, and gradually Figure 45. — Micro-photograph of an Amceba. 48 THE SIMPLEST ANIMALS — PROTOZOA the rest of the body flows, by a rolling movement, in the same direction. This creeping-rolling motion of the protoplasm enables the amoeba to move through the water. When the pseudopodium comes in contact with a minute plant upon which the amoeba feeds, the protoplasm of the pseudopodium surrounds the plant and takes it into the cell. The microscopic plant thus eaten by the amoeba is in- closed, with a small amount of water, in a tiny globe called the food vacuole (vak'u-ol). The food vacuole is to be thought of as a stomach in which digestion can take place, for the plant is digested in it. The nutritious parts are absorbed into the proto- plasm, the undigested parts are cast from the cell, and the food vacuole disappears. There is no well- defined cell wall ; there- Feelmg pseudopodium. Ectoplasm Endopldsm / \ £» Nucleus ; Walking pseudopodium Figure 46. — Diagram of an Amceba. f ore the amoeba IS an illustration of a living, naked cell. Near the center of the cell is a spherical mass of denser protoplasm called the nucleus. In many amoebaB the nucleus is not easily seen except by means of specially stained preparations. The rest of the proto- plasm in the cell is called cytoplasm (si'to-plazm). This does not appear the same in all parts of the amoeba. On the outside, there is a thin, almost transparent layer, called ectoplasm (ek'to-plazm : Greek, ecto, outside; plasma, form). The larger part of the cytoplasm is filled with numerous small granules and contains several vacuoles. This inner mass of cytoplasm is called endo- plasm (en'do-plazm: Greek, endo, within; plasma, form). The vacuoles in the endoplasm may contain food, water, or waste products. The food and water vacuoles are REPRODUCTION AND ENCYSTMENT 49 temporary structures, but the vacuole which collects the liquid waste is always present. When this vacuole reaches full size, it suddenly contracts and throws the waste into the water. This excretory vacuole is therefore called the contractile vacuole.1 29. Respiration. — The amoeba respires. From the air dissolved in the water, it obtains by diffusion the oxygen necessary to its life, and it gives off carbon dioxide from the cell. 30. Reproduction and Encystment. — The chief method of reproduction in the amoeba is simple (Figure 47 J. The living cell divides into two equal parts, forming two new cells. This process is known as fission (fish'un : Latin, fissus, cleft). When the food or water be- comes unsuited to supply the _ Am A □ rr J Figure 47. — Amceba Repro- needs of the cell, in order to ducing by Fission. live the amoeba often secretes (makes for itself) a thick wall completely surrounding the protoplasm. This process is termed encystment (en- sist'ment: Greek, en, in ; kystis, bladder). After the wall has been formed, the amoeba is able, for a long period, to resist cold, the drying up of the pond, or the lack of food. 1 No suggestion can be made which will always enable the teacher to secure amoebae. They are more frequently found in the slime and mud of Stagnant water than anywhere else. Paramoecia and other infusoria can usually be secured in abundance by placing a handful of hay or leaves in a jar and cov- ering them with the ordinary water used in the laboratory. This is called a protozoan culture, and should be started about four weeks before the material is wanted for class study. The length of time that the culture should stand can be lessened by adding a little beef-extract and by keeping the jar near a radiator. Water sufficient to keep the hay or leaves covered must be added from time to time. When a good culture of paramoecia is once secured, the jar should be kept from year to year, simply adding water to the dried hay left in the jar wheu infusoria are desired. 50 THE SIMPLEST ANIMALS — PROTOZOA 31. Paramecium. — One of the most common forms of Protozoa is the slipper-shaped paramcecium (para-me'- shi-um), which is more active than the amoeba. It is abundant in stagnant water and in the hay infusions pre- pared in the laboratory. (See Laboratory Suggestions.) LABORATORY STUDY There are certain kinds of Protozoa that are usually found in protozoan cultures. The most abundant form is the paramoecium. Make repeated examinations of drops of water from the protozoan culture, until you are able to find the paramoecium. Notice its shape, rate of movement, be- havior on meeting obstacles, and the like. Report on what you can make out. Compare the paramcecium with any other protozoan you can find, as to shape, rate of movement, size, color, etc. If available, ex- amine slides which show the nucleus of a protozoan. Make sketches that illustrate the above features. 32. Structure of Paramcecium. — The paramoecium, like the amoeba, is a single cell, but it has both a large nucleus and a small one. It has 0$& Contractile.. Vacuole -L •Cilia •Cuticle Trichocysts an endoplasm, an ecto- plasm, and a cuticle (ku'ti-kl), or cell wall. Through the cuticle, there extend great num- bers of cilia (sil'i-a), or threads of living proto- plasm. The ectoplasm contains many thread- like darts known as trichocysts (trlk'o-sists). These can be discharged. On one side is a fold or depression (the gullet) in which food is collected by the waving motion of the cilia. Within the cell are found food and water vacuoles Food Vacuole •Contractile Vacuole Figure 48. — Diagram of Paramcecium. REPRODUCTION, RESPIRATION 51 as in the amoeba ; but there are two contractile vacuoles, one at either end, and the food and water vacuoles are more numerous than in amoeba. 33. Locomotion and Defense. — The animal moves by the action of the cilia, the direction bein^ due to the angle at which the cilia are held. It can be observed that the animals move backward and forward, and that they also rotate on the long axis. Paramoecia defend themselves by discharging the trichocysts. This discharge occurs either as a result of cer- tain strong artificial stimuli, such as electric currents or chemicals, or naturally because of collision with certain other Protozoa. If attacked by some animal which feeds upon them, they discharge the trichocysts in the region of the attack (Figure 49). 34. Reproduction, Respiration. — Paramoecia reproduce by fission, i.e., an animal divides, producing two; these divide and produce two more. The process of fission goes on indefinitely (Figure 50). Like the amoeba these forms can encyst win mi conditions of life become unfavorable. They can then be blown about in dust. As in amoeba?, the oxygen which is necessary to respiration is obtained from the water. Excretory waste is cast from the body by the contractile vacuoles, which force it through the ectoplasm, (iases escape from the entire surface. Figure 49. — Paramecium. Being attacked by another Protozoan that feeds upon it. The trichocysts are dis- charged, and they force the foe away. Figure 50. — Para mcecium reproduc ing by Fission. 52 THE SIMPLEST ANIMALS — PROTOZOA ■ &S 35. Economic Importance. — Paramoecia consume consid- erable quantities of bacteria, but whether more harmful than helpful ones cannot be told. Therefore their economic value is un- certain. 36. Other Protozoa. — If one examines stag- nant water, a large num- ber of other kinds of Protozoa will be found. The more common forms are much like the para- mcecium and have many cilia on the body. Several of these large, ciliated Protozoa feed on the smaller Protozoa. Some of the common forms are shown in Figures 51-53. All of these various Protozoa can be grouped into classes, Figure 51. — Vorticella. m i!S'.-.«.Ji\:-i.v.' Figure 52. — One of the foraminfera. Figure 53. — Some Flagellate Protozoa. each with certain distinct characteristics. For instance, all Protozoa that have pseudopodia are called Rhizopoda. In PROTOZOA AND ALCOHOL 53 this group, the cells may be naked or may possess a haul mineral covering ; a second group of Protozoa are pro- • vided with one or more long, wavering threads called flagella (Ha-jel'la : Latin, flagellum, whip), and have the name Flagellata ; the flagella are longer than cilia and exhibit more complicated movement. A third class, known as Infusoria (in-fu-s Have — Kinds Observed are free swimming ? are attached by threads? have even motion ': have zigzag motion ? constant form ': varying forma ! 37. Protozoa and Alcohol. — Scientists have studied tin- relation of alcohol to the life processes of Protozoa. Nor- mally, such Protozoa as paramcecia divide a regular number of times each day. When a small amount of alcohol is placed in water containing paramcecia, the normal rate of fission is diminished. Professor Wood- ruff has shown by an extended and critical study that alcohol tends to prevent paramcecia from dividing as many times as they would under normal conditions. This means that alcohol hinders the growth of paramcecia. 54 THE SIMPLEST ANIMALS — PROTOZOA SUMMARY Protozoa are the simplest group of animals. They are found mostly in water, yet some are parasitic in higher animals. They are small and usually consist of only one cell. They reproduce mostly by fission. Some produce in man and beast diseases, such as malaria and the sleeping sickness of Africa. But the great majority of Protozoa are not harmful. QUESTIONS Compare the body of a protozoan with the body of a grasshopper. In what are they alike ? In what different ? How do the amoeba and paramcecinm compare ? Explain how the Protozoa eat, digest food, produce more Protozoa, and protect themselves. How do these vital processes compare with the similar vital processes in the grasshopper ? In what ways are Protozoa injurious to man ? Are they parasitic ? REFERENCES Galloway, First Course in Zoology, Chapter X. Hegner, Introduction to Zoology, Chapters IV, V, VI. Jordan and Kellogg, Animal Life, Chapters II, III. Kellogg, Animals and Man, Chapter V. Osborne, Economic Zoology, Chapter II. CHAPTER IV THE SIMPLER METAZOA 38. Metazoa. — The Protozoa just studied are single, free, living cells, while the grasshopper is made up of thousands of cells. The grasshopper is called a metazoan (mSt-a-zo'an : Greek, meta, after ; zoon, animal) because there are many cells in its body. The Protozoa and the Metazoa are alike in that both take in food, breathe, give off waste matter, and reproduce their kind. There are a number of organisms concerning which scientists disagree as to whether they are plants or animals. In zoology, these forms are known as Colonial Protozoa or simple Meta- zoa. We shall study two of these (Gonium and Vol vox) and then examine the sponges, which all scientists agree are Meta- zoa. 39. Gonium. — Gonium is an animal made up of sixteen separate cells held together by a mucilage- like secretion of the cells. Each cell works independently in getting food, breathing, giving off waste, and in reproduction. The colony moves by lashing the water with long protoplasmic 55 Figure 54. — Gonium. 56 THE SIMPLER METAZOA i /...'©" IMS? threads (flagella), two of which project from each cell. The advantage in rate of movement resulting from the union of cells is illustrated in rowing. Eight men in a large rowing shell can go faster than one man in a single, small shell. In reproduction, the sixteen cells fall apart, and each one grows into a new colony. 40. Volvox. — Volvox is a colony of hundreds of tiny green cells embedded in a hollow gelatinous sphere. Each cell has two flagella. For a time all the cells are alike and share equally in the work of the colony. But in reproduction only a few cells take part. In the simplest method, a few cells grow large and escape into the hollow sphere. There, they divide and grow into new colonies. Finally, the mother colony breaks, and the daughter colonies escape. The more complex method is like the reproduction of higher animals. Certain cells in the colony grow large and escape into the hollow sphere. They are the egg cells. Other cells of the colony enlarge and divide into large numbers of slender, free-swimming cells called sperm cells. The sperm cells escape into the hollow sphere and swim about. One sperm enters an egg cell and unites with it, forming a single cell, the fertilized egg cell, which can develop a new colony. 41. Division of Labor. — In gonium, the cells are alike in form and function, but in volvox, we find that a few cells have been changed in form in order better to perform the special work of reproduction. This is the first step in the division of labor. & Figure 55. — Volvox. SPONGES 57 This is well shown in the higher animals, where certain cells are grouped together for a given work. The diges- tive system contains cells which work to make solutions of the food eaten. These solutions nourish the whole body, not the cells of the digestive tract alone. Certain other cells are modified in such a way for secreting and holding lime that they form bones by which the whole body is benefited. Some cells are grouped to form muscles to be used in securing food and in enabling animals to escape from their enemies. Other cells are for the purpose of convey- ing and interpreting impressions, so that the animal may hear the approach of an enemy, or detect the presence of food. It is largely the carrying out of this " division of labor " that tells us the rank of an animal or a plant in biological classification. In the business world we know of division of labor. Years ago the cobbler made all the parts of a shoe. In our large shoe factories to-day we find no one man making an entire shoe. One man runs the machine that cuts the leather and does no other part of the work. He may have been a cutter twenty years, and he works rapidly and accurately. Another man runs the machine which sews uppers to the soles. He, too, is a rapid and skillful worker. Other men have their special lines of work to do. In the end they produce more shoes and better shoes than this same number of men could, if they were all cobblers and each finished his product. So in the world of business we find the same plan of division of labor that we are studying in biology. 42. Sponges. — Sponges are simple metazoa. In them we find division of labor carried out in a more complex way than in gonium and volvox. Simple sponges have a body in the form of a hollow cylinder. Water enters 58 THE SIMPLER METAZOA through the sides of the body and passes out through a hole in the top. A simple sponge, called Grantia, grows in salt water attached to docks or other objects submerged along the seashore. On examination, it will be observed that grantia is less simple than volvox. Figure 56. — Bath Sponge. A skeleton. 43. Structure. — Grantia is composed of three layers of cells which show division of labor. The inner layer is called the endoderm (en'do-derm). It consists of cells provided with flagella which, by their movement, produce a current of water through the central cavity. The water enters through the holes in the sides (inhalent pores) and is forced out through the opening at the top (exhalent pore). The water contains food particles which the cells of the endoderm have the power to take in and digest. The food solution is passed to the other cells in the sponge body by the process of osmosis. STRUCTURE 59 & it Figure 57. — Diagram. To show parts of sponge. This is a physical process in which gases or liquids of unequal densities, separated by a plant or animal mem- brane, tend to mix and become alike, the liquids or gases passing through the membrane. Thus the food digested is passed on and nourishes the cells of the middle and outer layers. The cells of the middle region form spicules (spic'uls) of lime (Figure 58) that pro- ject through the other layers Figure 58. and strengthen the whole body. The outer layer or ectoderm (ek'to-derm) serves as a protective layer and with the help of the spicules gives definite shape to the body. LABORATORY STUDY The sponge which we ordinarily handle is simply the skeleton, and is easily kept from year to year. Examine several kinds of sponge skele- tons and compare their shape, size, and the nature of the skeleton. How 60 THE SIMPLER METAZOA much water will the pores of the sponge hold ? Microscopic sections of Grantia are necessary if you are to make out the inhalent pores, the central cavity, and spicules. 44. Reproduction. — At certain times of the year the sponge reproduces by means of two kinds of cells (eggs and sperms) developed in the middle layer. A sponge may develop both eggs and sperms, but usually develops only one kind at a time. Cells from the middle layer move in between cells of the endoderm and grow large and round. These are the eggs (female cells). Other cells move into the endoderm layer and divide into many small ciliated cells (the sperm or male cells). The sperms are set free and escape into the water of the central cavity and out from the body of the parent sponge. A sperm enters the body of another sponge and when it finds an egg, fuses with it, thus forming the fertilized egg. The fertilized egg then begins to grow, and after a definite period breaks away from the parent, moves about for a time, and then settles down, attaches itself, and grows into a mature sponge. The immature sponge has the power of locomotion, but the mature form loses this power. Nevertheless the sponge is an animal. Reproduction that comes about through the fusion of an egg and a sperm is called sexual reproduction. The other method of reproduction, called asexual reproduction, also occurs among sponges. By this method, sponges form little buds or branches which develop into new sponges. 45. Spongilla. — Spongilla (spunj-il'la) is a fresh-water sponge. At the approach of cold weather, certain repro- ductive bodies are formed, known as winter-cells, and Figure 59. — Two Stages in the Development of the Sponge. RELATION TO OTHER ANIMALS 01 these escape from the sponge. They settle down to the bottom of the pond or stream and remain dormant until the approach of warm weather, when they grow into new sponges. They have a thick protecting coat which enables them to resist unfavorable conditions. 46. Economic Importance. — The spicules of the different sponges form a large part of their so-called skeletons. These spicules are, in some cases, composed of lime and form the limy sponges. In others, they are of silica and form the glass}?" sponges. The more important sponges have a skeleton made up of a hornlike substance which is flexible. This is the sponge of commerce. Great quantities of sponges are gathered from the sea by divers and by dredges. The living tissues arc allowed to decay, and the skeletons are then washed and dried. Some are bleached to form the white sponges. The sponges of best quality come from the Mediterranean Sea and the Red Sea. Sometimes fresh-water sponges grow in the water mains of cities and towns, causing the pipes to become clogged. 47. Relation to Other Animals. — No animal is known to eat the sponge. Sponges themselves feed on minute particles of food, which are carried in by the currents of water produced by the cilia of the endoderm. Some marine animals use the porous body of the sponge as a retreat. Certain sponges live in close relationship to higher forms of animals. One kind is always found growing on the legs of crabs. The movement of the crab carries the sponge to water richer in oxygen and food, and the crab is hidden from its enemies by its sponge covering. Each animal gains by this inter-relationship. Where two such animals as the crab and sponge live in this way the rela- tionship is known as symbiosis (sym-bi-o'sfe : Greek, syn, with ; bios, life). 62 THE SIMPLER METAZOA SUMMARY The transition from simple Protozoa, through the Colo- nial Protozoa, to the Metazoa is simple and direct. In gonium and volvox, the beginning of division of labor is noticed ; that is, one part of the body becomes dependent on another part for certain definite things. For example, one cell is devoted to securing food, while another produces eggs or sperms. The sponges are simple Metazoa in which the division of labor has taken the form of producing three layers, — the ectoderm, or outer layer ; the endo- derm, or inner layer; and a loosely formed middle layer. Grantia is a simple sac-shaped sponge which reproduces both sexually and asexually. The general manner of development by the sexual process is essentially the same in all the higher animals, including man. The bath sponges are the only ones of economic importance. QUESTIONS What can the single-celled protozoan do ? Compare with the Colonial Protozoa, gonium and volvox. Explain the meaning of division of labor in an animal. In what respects do sponges differ ? Of what use are they ? Why are not all sponges useful ? REFERENCES Hegner, Introduction to Zoology, Chapter VI. Jordan and Kellogg, Animal Life, Chapter II. Osborne, Economic Zoology, Chapter III. CHAPTER V OCELENTERATES. HYDRA-LIKE ANIMALS 48. Ccelenterates. — -The Coelenterates (se-len'te-rats Greek, koilos, hollow ; enter on, intestine) are simple metazoa, a little higher in development than the sponges. In the group are hydras (hl'dras), hydroids (hi'droids), jelly-fishes, sea-anemone (a-nem'o-ne), sea-fans, and corals. 49. Structure of Hydra. — The hydra is an in- teresting fresh water animal about a quarter of an inch in length. Its body is shaped like a little cylindrical bag with only one opening, the mouth, which is surrounded by a few, usually six, delicate, thread-like arms called tentacles (ten'ta-kls). The body is composed of three layers, the outer layer, ectoderm ; the middle layer, the mesoglea (mes-o-gle'a : FlGURE 60. - m.crophotographs of Greek, mesos, middle ; Hydra. G3 64 CCELENTERATES Figure 61. — Diagram of Body of Hydra. gloios, glutinous substance) ; and the inner layer, endo- derm. Each layer does some par- ticular work for which the others are not fitted. For example, the outer layer contains cells which are especially sensitive to stimuli and many modified muscle cells that enable the animal to move about. The inner layer contains cells provided with flagella which catch the food particles for the inner cells to digest. The muscular action of the outer layer moves the entire animal. The sensitive cells enable the animal to recog- nize its prey. The food digested by the inner layer is used by all the cells of the body. Thus we see an advance in the division of labor over that shown in the sponge. We shall observe a still greater increase in division of labor as we study higher animals. Tentacles are hollow, finger-like branches con- nected with the body cavity. They are pro- vided with stinging cells which help the hydra to capture living water fleas, and the like. These stinging cells have darts Figure 62. — Microphotograph of Body Wall of Hydra. REPRODUCTION 65 which are automatically discharged when the tentacles come in contact with little animals. The darts stun the prey and render escape impossible. The tentacles sur- round the food and carry it to the mouth, which opens directly into the food cavity. The action of the tentacles in doing this work sug- gests the idea that each tentacle has some way of realizing the efforts Endoderm Mesoglea Ectoderm Figure 63. — Diagram. To explain cell layers in Figure 62. of the others. We should keep in mind that in the meta- zoan the united cells are in connection with each other through the cell walls. This is true even if we are not able to trace the connections with the microscope. In the higher animals we shall find that connections between cells are made by means of nerve cells. The development of a nervous system only carries out division of labor to a greater degree. 50. Respiration and Excretion. — By osmosis, oxygen is absorbed from the water by the cells of the ectoderm. The water that enters the mouth carries oxygen, and by osmosis it is absorbed by the cells of the endoderm. At the same time the carbon dioxide from the cells is thrown off into the water. 51. Reproduction. — The hydra reproduces both sexually and asexually. In sexual reproduction eggs and sperms are produced by the ectoderm cells. The sperm cells escape into the water and, like sperm cells of all other animals, have the power of locomotion. The fusion of the egg cell and a sperm cell starts growth which results in the division of the egg cell into many other cells. 66 CCELENTERATES Hydras also reproduce asexually by budding. The buds soon separate from the parent and begin an independent life. Like the developing sponge, the developing hydra grows until it finally becomes a fully formed hydra. LABORATORY STUDY The living brown or green hydras can usually be found in the spring or fall in most fresh water ponds. They are easily collected by gathering the floating leaves and overhanging grass that is immersed in the water. Place this collection in a glass jar in the laboratory. In a couple of days the hydras will have moved from the grass to the sides of the jar. They can be examined by a small magnifying glass in the jar or be transferred to a watch glass and observed under the low power of the microscope. Watch the hydra contract, when jarred or touched. Note that the tentacles become very short. Try feeding with a small bit of raw meat. Make out the transparent ectoderm and the darker endoderm. Are there any buds ? What happens to the buds when the parents contract ? 52. Hydroids. — Hydroids are marine, hydra-like animals which are united in groups forming a tree-like colony (Figures 64-66). They are often mistaken for plants. Figure 64. — Microphotograph OF THE HYDROID ObELIA. Figure 65. — Diagram of the Hydroid Bougainvillea. HYDROIDS 67 When the young hydroid first begins to grow, it looks like the fresh water hydra (Figure 60). As the hydroid grows, branches form and on the end of each branch, tentacles and a mouth appear. Figure 66. — A Hy- droid Colony that Looks like a Plant. Figure 67. — A Hydroid Medusa. Each branch is able to capture food and, after it takes what it needs, the surplus is distributed to other parts. This is easily brought about, as a common digestive cavity con- nects all of the branches. The hydroid is termed a colony because all of the branches are united and help each other in getting enough food for all. Some of the hydroids form curious buds which develop into medusce (me-du'se). See Figure ^ ° Figure 68. — The Medusa Known as bi. As soon as the Pelagia 68 CCELENTERATES medusae are set free from the hydroids, they swim about and capture their own food. Each medusa is provided with either ovaries (o'va-riz), organs which grow egg cells, or spermaries (speYma-riz), organs which grow sperm cells. When the eggs and sperms mature, they are discharged into the water. A single sperm cell must fuse with an egg cell before the egg can begin to grow. This union of these two cells is called fertilization. The egg grows into an embryo (em'- bri-o), an immature stage dif- fering in different animals, and this gradually changes into a small hydroid. The several steps in this complicated series of changes are illustrated in Figure 69. The hydroids and medusa3 show a form of reproduction called alternation of generations, that is, they reproduce alternately sexually and then asexually. 53. Sea-anemone. — Sea-anemo- nes are animals allied to the hydra. The interior of the J <^k Figure 69. — Pennaria Tiarella. a. The hydroid colony ; b, one of the female medusae, much enlarged ; c, the egg of the medusas beginning to segment after it has been fertilized; d, e, f, further segmentation stages ; g, the blastula stage ; h, the free swimming larva (planula) ; i\ /, and k show the gradual transformation of the larva into a hydra-like colony. Branches grow on the stage shown in k until a colony like a results. This is the form that alterna- tion of generations takes in this hydroid. (Arranged from a monograph on Pennaria by C. W. Hargitt.) CORAL 69 body cavity is subdivided by many partitions which in- crease the digesting and absorbing surface. The sea- anemone reproduces by eggs and sperms. The resulting embryo is free at first, but later becomes fixed to some object and develops into the sea-anemone. There is no medusa stage. 54. Coral. — Geographies tell us of the many coral islands and reefs built up by the coral animals. These animals are coelenterates, most of them closely allied to the sea-anemone, but the coral animal secretes about the body and along the parti- tions calcareous (kal- ka/ re-us, limy) skele- tons which form the stone-like masses of the coral rock. The upper portion of the coral rocks is alive with these coral animals. The lower portion is made up of skeletons only. Suc- ceeding generations build upon the work of their ancestors. Corals reproduce much as trees grow branches, but at certain periods eggs and sperms are produced as in the sea-anemone. Then the embryo settles down, secretes its own skeleton, and this is added to the work of other corals. Sea-fans and sea-plumes are coelenterates which have the forms suggested by their names. A dried specimen of either looks as if a branch had been dipped in a solution and coated. The interior is of a horny substance. The exterior is covered with a limy secretion. Figure 70. — Some Common Corals. 70 CCELEN TERA TES 55. Economic Importance. — The corals alone of the coelente rates are of economic importance ; they add to many islands, protect others from being washed away, and in some cases form entirely new islands. SUMMARY The hydra-like animals represent an advance in the division of labor. The layers of their bodies are more definite and do their work better than in the sponges. Hydroids and the corals illustrate the formation of a colony. In some of the colonies the division of labor is more extensive than in others. The economic importance of the corals has been, and continues to be, very great. QUESTIONS Explain fully how the hydra gets its food and how some of this food finally nourishes the ectoderm cells. Compare the hydra and the hydroid. In what are they alike ? In what are they different ? How does the hydra reproduce ? How does the hydra get its oxygen ? Explain how the coral animal has been able to form islands. REFERENCES Darwin, Structure and Distribution of Coral Reefs. Hegner, Introduction to Zoology, Chapter VIII. CHAPTER VI THE STARFISH FAMILY. (Optional) 56. The Starfish Group. — This group of animals includes the well-known starfish, the sea-urchins, sea-lilies, and several soft-bodied forms such as the sea-cucumber. The technical name for these different animals is echinoderm (e-km'6-derm : Greek, echinus, spine ; derm, skin), mean- ing spiny-skinned animals. Most of these animals have a skeleton. Unlike that of man it is on the outside and is composed of cal- careous plates. In some forms, like the starfish, the plates are embedded in the skin, while in the sea urchin the plates fit edge to edge, forming a shell. The plates support many spines which project out over the body giving the spiny appearance char- acteristic of the group. Both the skeleton and soft parts are arranged in a radial manner. The presence of spines and the radial arrange- ment are two characters by means of which one can recognize most of the echinoderms. 57. The Starfish. — Starfishes are found in salt water. They are composed of a central region, called a disk, from 71 Figure 71. — Starfish. 72 THE STARFISH FAMILY which extend five arms or rays. On the disk is a porous circular plate. It is known as the madreporic plate (mad-re-por'ik : Greek, mater, mother ; poros, soft). It 3 Tfu1 Figure 72. — Diagram of Body of Starfish. c, liver ; v, stomach ; o mouth ; g , reproductive glands ; p, tube feet ; s, stone canal. serves to take water into a series of vessels by means of which the animal moves and holds on to rocks and shells at the sea bottom 58. Internal Structure. — If the upper portion of the animal is removed carefully, the internal structure can be examined. Each ray is nearly filled with masses of yellowish green sub- stance. This is a gland which forms the diges- tive fluids used in the stomach. The wrinkled mass in the region be- neath the disk is the stomach. The mouth is just below the stomach on the lower or oral side of the body. At the angles of the arms and extending into each ray are the reproductive Pi Figure 73. — Anatomy of the Starfish, glands, which vary in LOCOMOTION 73 size at different ages and seasons. According to the sex of the individual these glands produce either eggs or sperms, which are discharged into the water. LABORATORY STUDY Dried specimens of starfish serve well for general study. These may be compared with specimens which have been preserved in alcohol or formalin. Work out the several parts such as disk, arms, madreporic plate, spines, groove of the feet, and position and form of the mouth. If skeletons of sea urchins are available, they are interesting for comparison. 59. Life History. — The eggs and sperms fuse outside the body. In their development into adults they pass through a series of striking changes. The young or larval forms do not resemble the adults at all. This de- velopment through a series of marked changes is as striking as that seen in the insects and is likewise called a metamorphosis. 60. Food Taking. — The starfish takes its food in an un- usual manner. Most animals move the food to the mouth, swallow it or engulf it, and digest it within the body cavity. In the case of the starfish we find that the stomach is projected through the mouth and made to surround its food. In this position it digests and assimi- lates the food and then withdraws its stomach through the mouth and moves on slowly to some other place. A common food of the starfish is the clam. The arms or rays surround the clam, and the "hinge ligament" which holds the shell together is tired out, thus causing the protecting clam-shells to separate. The stomach is then pushed out, enveloping the clam. The digestive fluid is secreted and the dissolved clam is absorbed as food. 61. Locomotion, — The animal moves chiefly by means of the tube-like feet found in the groove on the under surface of the rays. These so-called feet make little sucking disks. 74 THE STARFISH FAMILY Figure 74. — Purple Sea Urchin. 62. Respiration. — Oxy. gen is taken from the water and carbon dioxide given off through little thin-walled, gill-like processes which cover the upper surface of the disk and arms. These gill-like processes pro- ject through holes in the exoskeleton. 63= Other Echinoderms. — The sea urchins are thickly covered with spines and have tube feet which, in many cases, may be greatly extended. When the spines are removed, an exoskeleton is revealed, which readily shows the radial arrangement characteristic of the echinoderm group. 64. Economic Importance of the Group. — Of echinoderms the starfish alone has an eco- nomic bearing. It is harmful. Living as it does in the region of the oyster and clam beds and feeding almost exclusively on them, the starfish annually destroys thousands of dollars' worth of clams and oysters. By removing the seaweed where the immature starfish gather and by dragging the oyster and clam beds great numbers of starfish are destroyedc In former times the fishermen used to break starfish to pieces on the side of the boat and throw Figure 75. — Sea Lily. ECONOMIC IMPORTANCE 75 them back into the water. It is now known that by bo doing they were but increasing the number of starfish, for starfish have the power to re-grow the parts broken orf\ Each complete arm could reproduce an entire starfish. This power to restore lost parts is known as regeneration (re-jen-er-a'shun). Many of the lower animals have this power to a marked degree, and all animals have it to some degree. SUMMARY The starfish group of animals is known by the presence of spines in the skin and a radial arrangement of the organs. Their chief economic relation to man consists in their great destructiveness to the oyster and clam beds. QUESTIONS Why are starfish so-called? How can they be distinguished from other animals ? How do they move ? Where do they live ? On what do they feed ? How do they breathe ? REFERENCES Brooks, The Oyster. Osborne, Economic Zoology, Chapter VIII. Poulton, All About the Oyster. V CHAPTER VII THE WORM GROUP 65. The Worm Group. — Here are found several distinct groups of animals that in advanced text-books of zoology are treated separately. The word "worm " is an old term which properly describes such animals as the earthworm, sea worm, leech, tapeworm, flat worm, and a few others. The word " worm ' cannot be correctly used for such larvae of insects as the " apple tree worm " or " currant worm." The worm group is divided into two classes — those whose body is composed of numerous segments (seg'ments) or rings, such as the earthworm, the sea worm, and the leech ; and those whose body is not segmented, such as the tapeworm and flat worm. The first class comprises the true worms, which are known as Annelida (a-nel'I-da). The second class, the unsegmented worms, have no single technical name, and are not believed by scientists to be true worms. They comprise a number of worm-like ani- mals which have hardly any features in common. Here are found the fresh water planarians, the parasitic tape- worms, liver flukes, and numerous round worms, of which the hair worm is an example. The planarian worm is one of the simplest of these un- segmented worms. It is found under stones submerged in stagnant water and in streams. It is frequently brought into the laboratory and lives easily in aquaria. 76 ®: H Mi t* &2» Figure 76.- -A Pla narian Worm. TRICHINA 77 The liver fluke is a parasitic flat worm which each year causes the death of many sheep by injuring their livers.1 Like some other parasitic animals the liver fluke requires two hosts to complete its development. The hosts of the fluke are the sheep and certain snails. The adult liver flukes form eggs and sperms in the liver of the sheep. The fertilized eggs par- tially develop in the sheep ; then as embryos they pass down the bile duct into the intestine and then out of the body. The ciliated (sil'i-a-ted) larva then makes its way into water or along dew-covered grass. If it comes in contact with a water snail in the water or a land snail on the grass, it enters the body of its second host, otherwise it dies. Once inside the body of the snail it completes a compli- cated development. By a bud-like process many young flukes are formed which finally emerge from the snail and make their way to the grass stems on which they encyst themselves. If this grass is eaten by a sheep, the diges- tive fluids set free the young fluke which goes up the bile ducts to the liver, where it grows to maturity. 66. Trichina. — Another unsegmented worm that is of economic importance is the Trichina (tri-klma), now gen- erally called Trichinella (tri'ki-neTla). This worm lives in the intestine of mammals and from the intestine mi- grates into the muscles of its host. In the muscle it becomes encysted and remains until the flesh is eaten by some other mammal. When pork, infected with this parasite and insufficiently cooked, is eaten by man the 1 The Animal Parasites of Sheep. Dr. Cooper Curtice. Bureau Animal Industry, United States Department of Agriculture, 1890. 78 THE WORM GROUP m ■ ■■ esMIh M?^ va a ■■■■ '•' . 1§ v i\*f '^^f if) , Figure 77. — Trichi- NELLA. cysts are dissolved by the digestive fluids and the worms are freed. These worms then develop eggs and sperms which after uniting mature into young worms and migrate through the intestine into the muscles. The activity of the worms at this stage causes a seri- ous inflammation of the tissues and a disease known as trichinosis (trik-in- o'sis), which is often fatal. Hogs con- tract trichinosis by eating refuse that contains the encysted worms. Government inspectors examine pork which is to be exported or sold in large quantities to see that it is free from these parasites. The smaller sales of pork by local dealers are not inspected and the only way to be sure of the harmlessness of the meat is to cook it thoroughly. Hair Worm. — The only importance that can be attached to these worms is the myth about their origin. In almost every school will be found students who believe that horse hairs placed in water will develop into " hair snakes." It would be a pity if a student still be- lieved this after a course in biology. Let us see how such a belief can originate and often be thought to be proved. The hair snakes live for a time in water and often in the watering Figure 78. — A Common Tapeworm. HAIR WORM 79 troughs where horse hairs are also found. Boys, and men too, sometimes put horse hairs in water and then after a few weeks examine the water and find these hair snakes. They conclude, since they put in the hairs and later found the "hair snakes," that the hairs grew to form the snakes or small round worms. If they had been as careful to look before any hairs were put iu, they would have seen these "hair snakes ': swimming about. A better test is to take a bottle of water, put in the Figure 79. — Hair Worm in Body of Grasshopper. hairs, and watch for developments. Such a test would show that no hairs turn into hair snakes. Hair snakes have a complete life history as clearly de- fined as other worms. They lay eggs which fuse witli sperms and form larvae. These larvse live as parasites in the bodies of insects and fishes and when mature make their way out of the bodies of their hosts. It would be natural, then, to find them in pools where horses drink and these parasitized fishes live, or in watering troughs into which grasshoppers may have jumped, as they so often do. We know at present no way in which lifeless matter can be made to live. A hair cannot become a worm and a crooked stick cannot grow into a snake. New life comes from the old. We sometimes read in the papers that 80 THE WORM GROUP some one has produced life from chemicals, but it is not believed at the present time to be possible. 67. The Earthworm is the simplest and best animal to illustrate the annelid group of true worms. When one examines a living earthworm, the head end can be determined as the one which first moves forward. Actually there is no head nor are there special sense organs. The muscles in the front end are stronger and the body rounder than in the back end. The back, or dorsal (dor's'l) part, of the worm is exposed to the light and is darker in color than the rest. This surface is rounder than the opposite (under) one which is in con- stant touch with the dirt when the worm is crawling. The flat surface upon which the worm crawls is the ven- tral (ven'tral) surface. The body of the earthworm is made up of a number of segments (rings) which are marked off by shallow grooves. Some of the segments in the front end are larger than those that make up the back end, but all are similar in shape. The number of segments depends mostly upon the age of the earthworm, and is from 60 to 150 in full- grown worms. 68. Locomotion. — The earthworm crawls by means of short, stiff bristles used as legs, the seta? (se'te : Latin, seta, bristle), which are found in all of the segments except the first two or three. These setce are arranged in four rows, two in each row. To understand how the setse are used in the locomotion of the earthworm it is necessary to know that the body wall contains two mus- cular layers. In the outer layer the muscles running around the body are called circular muscles. The inner layer, consisting of a number of bands running in the direction of the length of the body, are called longitudi- nal muscles. The contraction of the circular muscles INTERNAL STRUCTURE 81 lengthens the body and the contraction of the longitudinal muscles shortens it. The seta3 are connected with the longitudinal muscles. By pointing the set;e backward and bracing them against the ground, the worm can push itself forward. By pointing the setae forward tin- worm can instantly change the direction of its movement. LABORATORY STUDY One of the annelids should be studied with some care, as an illustration of an invertebrate animal. How do you determine the anterior and posterior ends ? Dorsal and ventral surfaces ? The number of segments '.' Compare several worms. The back region of the worm shows the most variation because new segments are being added. Where are the setae ? How does the earthworm move ? Place it on a glass. The front region of the body is most sensitive to touch. Test it. 69. Internal Structure of Earthworms. — This is shown diagrammatically in Figure 80. The internal structure consists of an outer tube, the body wall, and an inner tube, the digestive tube. The space be- tween the body wall and f"iji yr tdui wen digestive tube is known FlGURE 8o.- Diagram. as the body cavity or The organs of earthworm from the side. coelome (se'liim : Greek, koilos, hollow). Thin sheets of membrane pass from each furrow between the segments to the digestive tube. Beginning at the front end the digestive tube is given certain names for each distinct region, as follows : the mouth cavity; the pharynx (far'inks), with its thick muscular walls ; the esophagus (e-sof'a-giis), thin- walled and small ; the crop, a wide pouch ; the gizzard, where food is ground; and the stomach-intestine, a large, thin- walled tract extending through the last twro thirds of the length of the worm. 82 THE WORM GROUP The earthworm has an easily recognized nervous system which is found beneath the digestive tube. It consists of a continuous, minute, white thread with slight swellings in each segment. From these swellings, which are called ganglia (gan'gli-a: Greek, ganglion, swelling or tumor), short branches extend to the digestive tube and other organs. These branches are known as nerves. Toward the front end the nerve-thread parts and becomes double. Each part passes around the front end of the pharynx and enlarges to form two ganglia, the largest found in the earthworm. More nerves grow from these two large ganglia than from any of the others and so the term " brain ' is given to these two ganglia found in the dorsal surface of the pharynx (Figure 81). The organs of the earthworm are supplied with blood which is carried in a large dorsal blood vessel, a ventral blood vessel, and numerous branches. The blood is pumped by the contracting of the dorsal vessel and by the five pairs of tubes which pass from the dorsal to the ventral vessel around the esophagus. These five tubes are named aortic (a-6r'tlk) arches. Figure 81. — Earth- worm. Front end of nervous system. LABORATORY STUDY OF INTERNAL STRUCTURE Work out the internal structure of the earthworm. In dissecting, cut the skin along the dorsal surface, being careful to cut the many membranes that hold the digestive tube in place. Work out the size and position of the mouth cavity, pharynx, esophagus, crop, gizzard, and stomach-intestine. The white reproductive organs are located beside the esophagus. Locate the "brain," the ventral chain of ganglia. The dorsal blood vessels and aortic arches should be located. Make a sketch locating the organs in their respective segments. EXCRETION 83 70. Life History. — In the starfish group the sexes are distinct. The sexes in the annelids are distinct in some forms and in others the same individuals have both ovaries and spermaries. However, the sperms that unite with eggs always come from another worm. During the season when the ovaries and spermaries are forming eggs and sperms, certain segments, usually six in number, be- ginning with the twenty-eighth segment, and known as the clitellum (kli-tel'liim), pour out a gelatinous secretion which hardens into a collar-like sac around the worm. This sac is worked forward and as it passes the openings of the reproductive organs, eggs and the sperms from another worm are pushed into it. The sac continues to move forward and finally leaves the worm as a closed capsule. This capsule contains eggs, sperms, and fluid food. After the fusion of the eggs and sperms, the re- suiting embryonic worms begin to feed upon the fluid food in the capsule; later they feed upon each other until but one may remain eventually to bore or eat its way to the earth outside. From now on the food of the young worm is the soil. The earthworm is an example of an animal which has both ovaries and spermaries. 71. Respiration. — Oxygen passes through the skin di- rectly into the blood, which then carries the oxygen to the various cells of the body. The outer surface must be kept moist to permit the skin to act as a lung. 72. Excretion. — In each segment is found a pair of organs known as nephridia (ne-fiid'i-a), which look like little threads. These remove the liquid waste and carry it to the outside of the body. It is believed that carbon dioxide passes off through the skin, much as oxygen passes in. This taking in and giving off of these gases is accomplished by osmosis. 84 THE WORM GROUP 73. Food-taking. — The food of the earthworm is chiefly the soil in which it burrows. By means of an upper lip, which is a specialized anterior segment, and the muscular walls of the pharynx, it takes the earth into its body and the muscles of the digestive tube advance the food along its course. The soluble and therefore digestible parts are absorbed, and the remainder (the greater portion) is passed along to the outside. Earth- worms are not critical in the selection of their food, although they are not entirely without a sense of taste. 74. Economic Importance. — The value of the earthworms to agriculture is too great to be overestimated. In burrow- ing their way through the soil they leave passageways for water and air to enter, thus assisting plants to grow. They bring the fertile, swallowed soil to the surface. When the large numbers of the earthworms are considered, it is obvious that they are the great natural cultivators of the soil. 75 Other Annelids. — The sand worm or Nereis (ne're-is), a marine or salt water form, is another segmented annelid. It is more highly specialized than the earthworm, for it has biting mouth parts, tentacles, and eyes. It is an active swimmer at times. The development of the sand worm exhibits metamorphosis, while the earthworm hatches di- rectly into a worm without metamorphosis. Figure 82. — Dero. A common fresh- water annelid. SUMMARY In the worm group are included the unsegmented worms, such as tapeworms, liver flukes, and hair worms ; and the segmented or true worms such as the earthworms, sea SUMMARY s;> worms, and leeches. All of these worms have more per- fectly organized parts than the sponges and hydroids. The body of the earthworm shows the first steps in tin- formation of definite front, back, and ventral regions. The digestive tube is also specialized into pharynx, esophagus, crop, gizzard, and stomach-intestine ; and the name brain may be given to a slightly enlarged portion of the anterior end of the nerve cord. Small worms of various kinds are numerous in stagnant water. Some live as parasites in man and other animals, causing much suffering and loss of life. The earthworm as a cultivator of the soil has been of inestimable value to man. QUESTIONS "What kind of animals are called worms ? Is it proper to call " cur- rant worms" worms ? Why not ? What are they ? How do you recog- nize the anterior, posterior, dorsal, and ventral regions ? Compare the grasshopper or some other insect with the worm. Explain how the earth- worm moves ; makes its burrow. Compare the digestive tube with the digestive sac of the hydra. REFERENCES Darwin, Earthworms and Vegetable Mould. Jordan, Kellogg, and Heath, Animal Studies, Chapter VI. Sedgwick and Wilson, General Biology. CHAPTER VIII CRUSTACEANS AND RELATED FOEMS 76. Crustaceans. — The Crustaceans (krus-ta/ shuns : Latin, crusta, crust) are so-called because of their hard outer covering. They belong in the same group of ani- mals as the insects and are more highly developed than the worms. The body consists of a limited number of segments, each of which usually bears a pair of jointed appendages. The appendages are variously modified ; some aid in swimming, others in securing food, and others are used in walking. The jointed appendage is the characteristic expressed in the technical name Arthropoda (iir- throp'o-da : Greek, arthros, joint ; pod, root of pous, foot) given to the group to which all these animals belong. 77. Crayfish. — As a typical crus- tacean we have the common crayfish, or " crab " as it is known away from the seashore. The crayfish has nineteen pairs of append- ages adapted to different kinds of work. It lives in fresh- water ponds and streams where there is sufficient lime for its use in building up its outside covering (exoskeleton). The animal is divided into two regions, the head-thorax region and the abdomen. The segments of the abdomen 86 Figure 83. — Crayfish bearing Eggs. LIFE HISTORY 87 are clearly defined, but tlio.se of the head-thorax are so fused that they cannot be made out. The appendages of Figure 84. — Crayfish. the head-thorax region are the most important to the animal. Certain of these are fin-like and by their constant waving motion serve to carry food to the mouth. Others are elongated and serve for walking. One pair, the pinchers, are used for seizing and holding. The last abdominal segment and the appendages next to the last are broad and fin-like and together form a tail fin (caudal fin) for use in thrusting the animal backward, when it is alarmed. 78. Life History. — The sexes are distinct. The males may be distinguished from the females by the larger tubular appendages on the first and second segments of the abdomen. The egr^s of the female are carried for some time by the appendages of the abdomen, where they pass through their early stages of development,. The Figure 85. — Molted Exo- skeleton of lobster. 88 CRUSTACEANS young crayfish is unlike the adult in form, and approaches maturity only after passing through many changes (Figure 84). 79. Molting. — One of the interesting features in the study of the crayfish is the shedding of the external skele- ton. Being covered by a firm exoskeleton it is necessary that this be removed occasionally, in order that the animal may grow. Molting, in the case of the crayfish, is a serious and dangerous operation, as it is followed by a period during which the crayfish is without means of offense or defense. The crayfish usually hides until a new exoskeleton is partially formed. In the molting process the covering of the eyes and part of the lining of the diges- tive tract, as well as the whole exoskeleton, are shed. The crayfish molts every year of its life and several times during the first year (Figure 85). LABORATORY STUDY Place several crayfish in jars or aquaria and observe their behavior. Fill out the following report : DO THEY Move the Antenn.e? DO THEY Walk Forward ? Do THEY Walk Backward ? Do they Use Caudal Fin ? Do THEY Move Eyes ? What Organs Make a Cub- rent in Water ? Laboratory study on the appendages. Examine more fully than in the above and report the work of each pair of appendages. Compare one of the abdominal appendages with those used in walking and feeling. What is the work of the large pinchers ? How many fin-like appendages are found in the mouth region ? Notice that one of the mouth appendages has a flat part that extends in front of the gills. This part of the append- age is called the gill scoop or bailer. DIGESTIVE SYSTEM SI) 80. Food and Food-getting. — The food of the crayfish is both plant and animal, living and dead. One of the simple water plants, Chara (ka/ra), furnishes the crayfish with lime for its skeletons. Shells of snails and their own shed skins also help to supply lime. Crayfish seize food with their pinchers and move it towards the mouth. Small food particles are also carried towards the mouth by cur- rents of water produced by the mouth parts and the ab- dominal appendages. Particles of food are torn loose by the teeth or mandibles. 81. Digestive System. — The mouth is just back of the teeth, and connects with the stomach by a short esophagus. Figure 86. — Organs of Crayfish. The stomach is divided into front and back parts. The front part possesses a grinding structure known as the gastric mill, which serves to shred and crush the food and make it ready for digestion in the back part. The liver. or digestive gland, pours a fluid into the stomach, which prepares the food for absorption by the walls of the stom- ach and intestines. The intestine begins at the back end of the stomach and extends to the last segment. 90 CRUSTACEANS 82. Respiration. — Crayfish obtain oxygen from the water by means of gills which are well covered by the overhanging skeleton of the head-thorax region, but are really outside of the body. Most of the gills are plume-like in shape and are attached to the appendages, but some of them are attached to the thorax. Water is made to circulate through the gill chamber by means of the gill scoop or bailer. The finely branched gill affords a large amount of surface for the absorption of oxygen. 83. Circulatory System. — The crayfish has a well-devel- oped heart from which extend several arteries- that carry blood to the various parts of the body. The blood returns to the heart through veins and through several irregular ducts called sinuses (si'-nus-es). As the blood flows through the body it loses oxygen and receives carbon dioxide. Fresh oxygen is absorbed by means of the gills which, at the same time, pass off carbon dioxide from the blood into the water. 84. The Nervous System. — In the crayfish this is made up of a brain, ventral nerve chain, and many nerves. The eyes are borne on a pair of short movable stalks. The special senses are well developed, and the sense of taste is keener than that of most lower animals. 85. Excretion. — The organs for excretion of waste are the green glands that are found at the base of the antennas. Blood going to these glands loses some of the waste which it has gained in its course through the body. The method of purification of the blood in these glands is much the same as in the kidneys of the higher animals. 86. Other Crustaceans. — Shrimps, lobsters, and crabs are crustaceans of much economic importance, because of their food value. The trade in these animals amounts to millions of dollars each year. In order that these important food animals may not become exterminated by careless and ARACHNIDS 91 excessive fishing, the state and national governments have attempted to control the numbers taken and have also established hatcheries in which the eggs are hatched and the young protected dur- ing the earliest stages of their development. Crustaceans of less economic importance are the barnacles which cling to rocks, wharves, and steamships ; the hermit crabs that live in the shells of mollusks (mol'lusks); and the smaller fresh-water crustaceans such as the Cyclops (sl'klops), Daphnia (daf'ni-a), and Cypris (si'pris) which are barely visible to the unaided eye. Figure 87. — Soft-shell Crab. Figure 88. — Pill Bug. Figure 89. — Cyclops. 87. Arachnids. — The spiders, scorpions (skor'pi-iins), ticks, and mites are arthropods that are grouped together under the name Arachnida (a-rak'ni-da : Greek, araehne* spider). The spiders and scorpions have eight walking appendages. The forward pinchers of the scorpions arc mouth-parts, and not walking appendages. The harvest- 92 CRUSTACEANS man (daddy-long-legs) is a harmless arachnid which does good by destroying injurious insects. The spiders catch insects either by pounc- ing upon them or by entangling them in their webs. Scorpions sting severely, but the wound, although painful, is rarely fatal. Some ticks and mites are parasitic on man and beast. 88. Myriapods. — An- Figure 90. - Daddy-long-legs. Other group of arthro- pods is the Myriapoda (mir'i-a-po-da : Greek, myrias, many), a group which in- cludes animals of many legs such as the centipedes Figure 91. — Spider. Figure. 92. a. Thousand-legged worm ; b, Centipede. (sen'ti-pedz) and "thousand-legged worms." The centipedes are provided with poison glands, and their bite SUMMARY 93 is fatal to some of the smaller animals and painful to man. The thousand-legged worms are harmless. Note. Insects have been studied also in Chapters I and II, but it should be remembered that they are arthropods. SUMMARY An animal belongs to the arthropods if it has more than two pairs of appendages which have several joints in them. They also have an external skeleton which is shed at irregular intervals in order to allow the animal to increase in size. The body of the crayfish shows that part of the segments have fused to form the head-thorax region. The members of this group vary much in size and habits. Lobsters and crabs are valuable for food and for this reason should not be caught when they are small. QUESTIONS What kind of animals belong to the crustaceans ? How can you dis- tinguish one from a worm ? From a hydroid ? Explain why insects are arthropods. Which groups of arthropods are beneficial ? Which are harmful ? What do you mean when you say that an insect is beneficial or harmful ? REFERENCES See Chapter II. CHAPTER IX THE MOLLUSKS 89. The Mollusks. — This group includes such animals as clams, oysters, snails, slugs, squids (skwids), and octopi (6k't5-pi). These forms differ from the crustaceans in having a soft, unsegmented body and, in most cases, a shell as their exoskeleton. The squids have a shell that is internal, and the shell is absent in some of the snails. 90. Clams. — The fresh water clam is a convenient type of mollusk to study. It is found in canals and in many streams and lakes. This clam has two shells or valves and, when moving naturally, the hinge is upper- most, while the opened valves allow the foot to be ex- tended into the mud. The foot is a thick, mus- cular mass, not at all foot-like in appearance, but it enables the clam to move, although slowly and at an uneven rate. 91. Structure. — The structure of the fresh water clam shows how it has adapted itself to its peculiar method of life. The shell is lined with a membrane called the mantle. The mantle secretes the shell-material and adds to its size year by year. At the back, the edges of the mantle are united at three points, 94 Figure 93. — Clam Showing Foot. Water enters through i.s., inhalent siphon, and leaves the body of the clam through e.s., exhalent siphon. STRUCTURE 95 Showing mantle and muscles, a.a. an- terior adductor muscle ; p. a, pos- terior adductor muscle. thus forming two openings known as siphons (si 'tons). Through one of these siphons water enters, carrying food and oxygen. Through the other the water passes out, carrying the waste from the body. Between the mantle and the body proper are gills, which hang free in the shell cavity. The gills are filled with holes through which the water Figure 94. — Right Shell of Clam passes. The foot is attached directly to the body proper and is the part of the clam hard to chew when it is eaten. The foot and body form a solid mass that nearly fills the space between the shells. The two valves of the clam shell are held together by means of strong muscles, attached to each shell. One of these is located in front of the body and is known as the anterior (front) adductor (ad-diik'ter) muscle: the second is just back of the body and is the posterior (back) adductor muscle. When these two muscles contract, the two valves are held tightly together. Before the live clam can be examined these two muscles have to be cut, as it closes its valves when handled. When the clam is dead, these muscles relax and the hinge forces the valves apart. It is not safe to eat clams and oysters that have died in their shells. Figure 95. — Digestive Tube of Clam m, mouth ; s, stomach ; i.c, intestine. 96 MOLLUSKS When the two adductor muscles are cut free from the valves, a round or oval surface is seen which is marked off from the rest of the interior of the shell. These areas are called muscle scars (Figure 94). When the empty clam shell is examined, it is found that the hinge, sometimes called the hinge ligament, is elastic. This is shown by compressing the two valves and seeing how promptly they open when the pressure is taken off. Where the two valves come in contact just beneath the hinge ligament, a blunt projection of one shell fits into a depression in the other. These are called the hinge teeth. LABORATORY STUDY Live clams can be secured in the market during the school year. The dissection of the clam is too difficult, but the arrangement of the organs in the mantle cavity can be studied. The position of the adductor muscles, foot, gills, palps, heart, etc., should be observed. Examine a small portion of a gill under the microscope for cilia. A variety of shells of clams should be studied in which hinge, muscle scars, and hinge teeth are examined. Compare clam and snail shells. 92. Locomotion. — The movements of the fresh water mollusks are extremely slow. In the clam the foot is forced out of the shell by the blood, which flows into it and causes the foot to be greatly enlarged. Muscles attached to the shell and front of the foot contract and pull the shell forward over the extended foot. 93. Food. — The food of the clam consists of microscopic plants and animals that . are caught in a sticky fluid (mucus) on the gills, as the water passes through them. The food, together with the mucus, is moved into the mouth by means of cilia. The mouth is simply an open- ing into the body and the cilia are on triangular flaps or lips (palps) on either side of the mouth. From the mouth food passes into the digestive canal, where the nutritious parts are absorbed (Figure 95). - . " 1 ■ N CIRCULATION 97 94. Respiration. — The clam, like other aquatic animals, gains its oxygen from the water and gives off carbon dioxide. A close inspection of the mantle shows the pres- ence of blood vessels which are more numerous than in the gills. For this reason, the mantle is regarded as the main organ of respiration, although the gills also assist. 95. Life History. — In clams the sexes are distinct. Kggs formed in the ovaries of the female fuse with sperm cells from the males taken in with the water through the siphon. These sperm cells have reached the water through the upper siphon. Thousands of embryos form in the body of the female and develop into larvse in the outer gills which, thus become greatly distended. Later the larvse pass into the water through the upper FlGURoF96^MBRYO 1 * That attaches itself The larvae of many fresh water clams to a fish. have hooks on their shells and by means of these they are able to cling to the gills or body of a fish, where they live as parasites for several weeks. They absorb food from their host and are carried from one place to another and are thus scattered. After a few weeks they leave the host and settle down to lead an independent life. 96. Excretion. — The wastes of the body are absorbed by the kidneys and passed out into the water through the upper siphon. 97. Circulation is well developed.1 From the heart the colorless blood is carried through arteries into smaller tubes, and returns, through veins, back to the heart. 1 The three chambered heart lies in the dorsal region, near the hinge, in a little soft-walled chamber, the pericardium (pe"r-i-c&r'di-um : Greek peri, around; cardia, heart). 98 MOLLUSKS 98. The Nervous System is not so well developed as in the crayfish. There are three groups of ganglia (nerve cells). One located far back in the body near the posterior adductor is called the visceral ganglion because it largely regulates the activities of the viscera (vis'se-ra), the inter- nal organs of the body. Another in the foot region is called the pedal (pe'dal) ganglion, and regulates the movements of the foot. A third located in the region of the gullet (esophagus) is the cerebral ganglion, which regulates the activities of the part near the mouth. All of these are connected by nerves. 99. Digestive System. — The mouth, which is located under the anterior adductor muscle, leads through the short esophagus to the stomach. The intestine winds through the foot region forming a loop, finally ascending and passing through the pericardium and between the chambers of the heart itself and opening into the upper siphon (Figure 96). 100. Snails. — Snails having one valve are called uni- valves as distinguished from clams, oysters, etc. which are called bivalves because their shells are formed of two valves. The greater number of snails are marine (live in salt water), although some live in fresh water and some on land. Snails have a broad foot which is used as a creeping disk. There is a head region provided with eyes and tentacles. The mouth of the snail is provided with a rasping structure known as the lingual ribbon (lin'gwal : Latin, lingua, tongue) by means of which it is able to cut and bore its way, even Figure 97. — Snail. Figure 98. — Tongue of Snail. (Magnified.) SQUIDS, CUTTLE FISH, AND OCTOPl 99 through rocks. Land snails by osmosis get oxygen from the air through the mantle, while water snails use gills and take their oxygen from the water. Figure 99. — Snail Shells. In the garden slug the shell when present is thin and affords small protection. 101. Squids, Cuttle Fish, and Octopi belong to the Cephalo- pods (sefa-lo-pods : Greek, kephale, head ; pod, foot), the highest division of the mollusks. The nervous system is highly devel- oped. The eye of the squid in particular is complex and more like the eye of vertebrates than of any animal thus far considered. The mouth of cephalopods is surrounded with ten- tacles. A common squid, Figure 100. — An Octopus. 100 MOLLUSKS Sepia (se'pi-a), has ten arms or tentacles, two long and eight short. It moves itself forward rapidly by shooting out water from a siphon in the collar region. When pursued, the squid ejects an ink-like fluid which clouds the water, concealing it from its prey and facilitating its escape. Cuttle fishes are similar to squids, the marked differences being in the shape of fins, the form of the eyes, and the shape of the longer tentacles. The octopi are the largest members of the group. They have eight tentacles, which in some cases reach a length of thirty feet. The stories about the size and behavior of the octopi are often exaggerated. 102. Economic Importance of the Group. — Clams, scallops, oysters, and snails are used as food in all parts of the world. In this country, oysters are gathered in great abundance from Chesapeake Bay and other bays along the Atlantic Coast. The edible clams are of two kinds. The round clam, Venus mercenaria (Ve'nus mer-se-na/ri-a), is more generally used as food, but the other kind, the soft-shelled clam, Mya arenaria (Mi'a ar-en-a/ri-a), is eaten extensively near the seashore. The soft-shelled clam has a long siphon which may be extended several inches beyond the valves (Figure 101). The scallop (skol'lup) is another mollusk that is eaten near the shore more extensively than elsewhere. This mollusk has but one adductor muscle, which is the edible portion. Clams and oysters are raised artificially and regularly planted on natural feeding grounds. Care is taken to Figure 101. Soft-shell Clam. a, b, siphons; m, mantle; s, shell; /, foot. Jean Louis Rudolphe Agassiz was born in Switzerland, in 1807, and died at Cambridge, Massachusetts, in 1873. He was especially noted for his work in geology and ichthyology (the science of fishes). Agassiz came to the United States in 1846 on a scientific expe- dition and took up his residence here, becoming Professor of Zoology and Geology at Harvard, and Curator of the Museum of Comparative Zoology at Cambridge. He explored the Lower Amazon in 1865-66. In 1871-72 he accompanied the Hassler expedition to the South Atlantic and Pacific. Few have done more than Agassiz to popularize science, and few teachers have trained so many young and rising naturalists. ECONOMIC IMPORTANCE 101 have such natural enemies as the starfish removed, and, in the case of oysters, brush and shells are added that they - ': \ w Vi? ■ ffmm > - \ - ■ \ I • V. \ Figure 102. — Stages in Life History of Oyster. may fasten to these rather than sink to the bottom, where they become covered with mud. . The culture of oysters and clams near the mouths of rivers contaminated with sewage is unsanitary, and dis- ease may be caused by eating such mollusks raw. This Figure 103. — Barnacles and Clams Growing on Oysters. 102 MOLLUSKS is one reason for the laws regulating the disposal of sewage, and for government inspection of the feeding grounds. SUMMARY The parts of mollusks are not arranged in segments like the earthworms or crustaceans. The usual presence of a shell and mantle and the fact that the soft body is not divided into segments helps to distinguish a mollusk from any other animal. The microscopic food of the clam is caught in the mucus and carried by cilia to the mouth. The clams and oysters are valuable for food but should not be eaten if taken from water contaminated by disease germs. Mollusk beds should be protected from such contamination. QUESTIONS What are some of the common mollusks ? Where do they live ? How do they get their food ? What ones are used for food by man ? REFERENCES Brooks, The Oyster. Cambridge Natural History, Vol. III. Kellogg, The Shellfish Industries. Linville and Kelly, Zoology. CHAPTER X PISHES 103. Vertebrates. — All of the animals thus far studied are grouped together under the name of Invertebrate*. because they have no backbone. We are now to study the Vertebrates, animals with a backbone, such as fishes, frogs, snakes, and birds. The presence of a backbone in vertebrates is their most conspicuous characteristic. The formation of the back- bone is always preceded by the growth of an embryonic Figure 104. — Skeleton of Fish. Note backbone. group of cells that do the work of a skeleton. This embryonic group of cells forms a structure which is called the notocliord (no'to-kord : Greek, notos, back; chorda, cord). In all of the true vertebrates (such as fishes, frogs, etc.), the notochord is gradually absorbed and the backbone takes its place, but between the vertebrae it remains as cushions. But in the fish-like animal railed 103 104 FISHES Figure 105. — Perch. Amphioxus (am-fi-oks'us), the notochord persists and there is never a true backbone. The notochord is always found above the food tube and below the spinal cord. Another characteristic common to all vertebrates is the presence of gill-slits. These are external openings on Figure 106. — Sunfish or Pumpkin Seed. VERTEBRATES 105 each side of the neck that in the fishes allow the water to pass over the gills. Such structures are of use only to aquatic animals, and yet all vertebrates have them at some time in their development. In most vertebrates the skeleton is composed of bone. There are usually two pairs of appendages (legs, wings, or fins) attached to the body at the shoulder and hip. Here special bones join the limb to the body. The bones in the shoulder are known as the pectoral (pek't6-ral) Lr ^ 1/ ' ■ *^^ * J#*-^>, P^^^ HH| %# "V^^ **j •' \ s* * K,m ;. -V *"&:'-*> *T *5T Figure 107. — Catfish, Bullhead, or Horned Pout. girdle ; while those in the hip are termed the pelvic (pel'vik) girdle. In the snakes, only traces of legs are found (Figures 104, 139, and 158). A further distinguishing feature of all vertebrates is the well-developed nervous system, with its large brain. The sense organs, eyes, ears, and the like, are also better developed than in any of the invertebrates. Oxygen is obtained by external or internal gills in most aquatic animals and by lungs in all other vertebrates. In many vertebrates the skin is an active agent in the inter- 106 FISHES change of oxygen and carbon dioxide and particularly in those animals which have a thin, moist skin like frogs. 104. Fishes. — The fishes are vertebrates, that is, they have a notochord which as they develop gives place to a vertebral column. There are four large divisions of fishes (1) the lampreys (lam'priz) and relatives, (2) the sharks and relatives, (3) the bony fishes, and (4) the small 1 '2~-T~~*i'mw ^Vj|S BwSjI&ftj^^ - ; -*2— ! - : A L Figure 108. — Brock Trout. group of fishes with lungs. The most important group in numbers and economic importance is the bony fishes. This group- includes the salmon (sam'un), trout, bass, whitefish, pike, shad, menhaden (men-ha/d'n), cod, mack- erel, herring, sardine, etc. Typical bony fishes are the goldfish, perch, and sunfish (Figures 105-108). 105. External Parts of a Fish. — The external parts of a fish show a well-marked head attached directly to the trunk ; a trunk region, the largest part of the body ; and a tail region which is sometimes as long as the trunk. In a bony fish the mouth is at the front end of the head. The jaw bones, bearing many small, needle-like teeth, are not firmly attached to the skull. The side of EXTERNAL PARTS 107 the head next to the trunk is protected by a piece of bone that covers the gills (gill cover or operculum, 6-peV- ku-liim), and the openings leading into the nostrils, which do not connect with the mouth cavity. The trunk bears a number of fins. Each fin is fur- nished with several bony fin-rays covered by a thin fold of skin. On the shoulder and hip regions of the trunk, the fins occur in pairs and are called the pectoral and pelvic fins. Several fins are found that are not in pairs. These are the median fins of the trunk. The caudal or posterior re- gion of the fish ends in a large median fin. The tail region is chiefly important in locomotion, but the fins also help in balanc- ing and steering. Scales cover the trunk and tail, each one overlapping like the shingles of a house. The skin is full of mucous glands that keep the fish covered with slime. Both the slime and the scales protect the fish (Figure 109). Figure 109. — Scales of Fishes. (Magnified.) LABORATORY STUDY Study living fish such as goldfish or perch. Place one or two in an aquarium and observe their behavior. Fill out the report below. Number Number of Paired Fins Number of Unpaikkd Fins Which \i:k I -i D i" I><> the of Fins Advance ? Stop ? Balance f \'.\ bsMovi ! 108 FISHES Note the shape and relative position of the head, trunk, and tail region. The gills are covered by a bony shield, the operculum. What is its size and how attached ? Where are the eyes located ? Do they move ? Can the eyes be closed ? How is the body covered ? Of what use is this covering to the fish ? 106. Respiration. — Water is taken in through the mouth and passes out through two openings, one on each side of the neck. In each opening four or five gills are found. The gills are made up of numerous, small, very short, fleshy threads or filaments. Into each filament a blood vessel penetrates and here the blood throws off carbon dioxide and takes oxygen from the water by osmosis just as the blood of the crayfish does. The thin-walled gill- filaments are adapted to respiration in the water. The water is drawn into the mouth and forced out over the gills, in much the same way as water is pumped from a well. When a fish opens its mouth, the water rushes in. As the mouth is closed, the floor of the mouth and throat is raised slightly, pushing the water against the side of the neck and through the gill opening. The mouth is thus emptied of water so that when it is opened again more water flows in. 107. Food Taking. — Fishes eat insects, worms, crayfish, snails, and other fish. The teeth of fish serve to seize, tear, and hold food. None of the fish have teeth which are adapted to crushing or chewing the food, as is the case among the higher vertebrates, like the dog, horse, and man. Fishes which eat minute animals and plants have many sharp pointed projections on the inside of the gill arches which act as strainers and gather quantities of this small food as the water passes over the gills. These projections are called gill-rakers. Their development seems to vary in proportion as they are needed for service. Fishes that feed on crayfish and on small fish have no use for gill REPRODUCTION 109 rakers or strainers and accordingly their gill rakers are undeveloped. 108. Special Senses. — The eye is well developed. It is globular and projecting, and is believed to be near-sighted. The organs of smell are usually located in the nasal cavity. In the bull-head, they are found in the feelers, on the head, and even in the skin of the tail. The ear is under the skin, and there is no external opening. As water conducts sound vibrations more readily than air, no device for gathering sound waves is necessary. 109. Circulation. — The blood of fishes is carried in well- defined blood vessels and a heart of two chambers. The blood is sent from the heart to the gills, where it is purified of carbon dioxide and receives oxygen. It is then carried by means of arteries to other parts of the body, where the oxygen in turn is given up and carbon dioxide is received. The blood from the gills and other parts of the body is returned to the heart through veins. Because the blood of fishes is at a lower temperature than the blood of man, they are called cold-blooded animals. 110. Reproduction. — The sexes of fish are distinct. At certain seasons many fish migrate upstream to lay their eggs (to "spawn"). Eggs are laid in large numbers by the females, and in the same locality sperm cells are dis- charged into the water by the males. The sperms unite with the eggs. The fertilized eggs hatch after thirty or forty days, or longer, depending on the kind of fish and the temperature of the water. The yolk of the eggs is attached to the young fishes 'for many days after they arc able to swim, and they need no other food than that sup- plied by this yolk (Figure 111). The spawning habits of fish must be understood thor- oughly if they are to be raised artificially, as is done in the many fish hatcheries. Most states have scientific game 110 FISHES laws which protect the fish during their egg-laying period when they are easily caught and when the destruction of even a few fish means the loss of thousands of eggs. Spawning habits vary greatly. Some fish, like the sal- mon, make long journe}rs from the sea to 4;he head waters of rivers and streams to deposit their eggs. The Colum- bia River is famous for the number of salmon which spawn there. Other fish, like shad, go up a river only a short distance to lay their eggs. Many shad, for instance, go Figure 110. — Eggs of Land-locked Salmon. up the Hudson River in New York state. In the case of herring, the eggs are laid in the sea and float on the sur- face. Eels go down from the rivers and streams to the sea to lay their eggs, the young eels, when small, migrat- ing up the river. Millions of small eels no larger than needles are found in the Hudson at certain seasons. 111. Fish Hatcheries. — In the natural state, many eggs are laid that never hatch because the sperm cells do not come in contact with them, and of the fishes that are hatched only a small proportion reach maturity. As it is a matter of great economic importance that fishes be saved from extermination and their numbers largely increased, FISH HATCHERIES 111 the governments of the world have established hatcheries where fish are raised in great numbers. In these hatcheries the eggs are taken from the female and placed in a jar, and the mass of minute sperm cells or "milt" is taken from the male and poured over the eggs, Figure 111. — Young Fish Showing Yolk Sac. so that practically all the latter hatch. Then by^ giving the developing eggs protection, and the young fish sufficient and proper food, nearly all of these eggs develop into active fish and the great loss that comes to the fish develop- ing in their natural environment is prevented. When they are able to take care of themselves, these fry, as the young hatchery fish are called, are taken to natural feed- ing grounds. In New York state and most other states pKppg Figure 112. — Young Fish Fry. there are state hatcheries where such fish as shad, pike, lake trout, salmon, brook trout, and others are raised by millions. The fish that are most useful as food are taken by hooks, nets, and seines, under certain restrictions. Those like brook trout which are caught as much for sport as for food can be taken only by a hook and line and in certain seasons; 112 FISHES the season of the year depending upon the time of spawn- ing. The brook trout spawns in August and September, while the rainbow trout does not spawn until February or March. 112. Care of Young. — Some fish, like the sticklebacks, build nests of sticks and leaves in which the eggs are placed and guarded. Bass and sunfish make a circular depression several feet in diameter near the shore and lay their eggs on these so-called ubeds." These beds are guarded zealously by the males, who drive off or carry away crayfish and small fish which feed upon such eggs. In former times men sought for these " beds " and by dropping a baited hook caught the bass while defending their eggs. Fortunately this practice is now illegal. Generally, adult fish pay no attention to their young and in many cases they devour young of their own kind as quickly as fish of other sorts. SUMMARY The term vertebrate is given to all animals that have a backbone. All have gill slits, either while young or as adults. Fish have scales and breathe by means of gills. Their eggs are usually laid in the water and receive no care from the parents. A few fish prepare a crude nest which they guard. QUESTIONS What are some of the structures that all chordates have ? Why is the word vertebrate used ? What are the common fishes near your home ? What ones are sought for food ? What is being done to keep up the supply of fish in your state ? What do fish eat ? REFERENCES Fish Manuals of the U. S. Commission of Fish and Fisheries. Jordan, Fishes. Jordan and Evermann, American Food and Game Fishes. CHAPTER XI AMPHIBIANS 113. Amphibians. — Frogs and toads are the best known animals of this group ; but here belong also the Sala- manders (sttl'a-man-ders), frequently miscalled lizards (see page 131). The Am- phibians (am-fiL/i-ans : Greek, amphi, double ; bios, life) are all small, the largest one found in America being a salamander (Crypto- branchus), rarely more feet long. Amphibian is used to explain the habit which frogs, toads, and certain salamanders have of spending their larval (tadpole stage) life in the water and their adult life on land, or partly on land and partly in the water. which is than two This term Figure 113. — Some Common Sala- manders. LABORATORY STUDY Place one or two frogs or toads in a small jar or box and observe the points mentioned in the report below. DO THEY Wink? Can tiiky Protect their Eyes ? How Do they I . i;t An: ': Can tiiky W \ ik F Hop ? How Do l 1 1 B Y 8w] M J HOW Do THOT Uatoh \ Y\.\ :• 113 114 AMPHIBIANS Figure 114. — Common Frog. 114. Frogs. — There are several kinds of frogs, one of which, the leopard frog, is found generally distributed throughout the United States. It can be recog- nized by the presence, on the dorsal surface, of many brownish or green- ish spots, edged with white, which help the frog to escape the notice of his enemies as he squats among the water weeds. These colors form rather definite bands on the hind legs, though there is much variation. The general form of the body, the shape of the head, and the long hind legs adapted for jumping are much the same in all frogs. LABORATORY STUDY Compare the general shape of fish and frog. How do the colors differ ? Show how the legs and feet are adapted to the way the frog lives. Is the frog sensitive to touch in various parts of the body ? Examine the eyes. Open the mouth and see that the frog can draw in its eyes. The ear membrane is on the side of the head back of the eyes. Pass a probe through the ear membrane of a dead frog and see where it comes out in the mouth. This is the opening of the Eustachian tube. How far can the living frog see ? Notice the method of breathing. See the throat move up and down. Hold the frog under the water and gently rub its sides. It will usually croak. Thus we can prove that the frog is able to make the air travel from his lungs to his mouth and back again while under water. 115. Habitat. — Frogs are seldom found far from some pond or stream and they are usually seen on the bank. When disturbed, they jump into the water, swim to the bottom, stir up the mud, and quietly come to rest a short distance from the place where they entered. As INTERNAL STRUCTURE 115 the nights in the fall grow cool, frogs make ready to spend the winter in a state of inactivity. During the warmer part of the day, they may be seen sunning them- selves on a bank, but as soon as ice forms on the water they remain on the bottom or become buried in the mud. The lungs are emptied of air, the heart beats decrease, and all of the usual living processes take place more slowly. This habit of passing the winter in a state of inactivity is known as hibernation (hl-ber-na/shiin). All of the amphibia, reptiles (Chapter XII, page 129), and several of the mammals hibernate during the winter. 116. Food. — Frogs are greedy creatures and will eat almost any animal small enough to be swallowed, such as insects, worms, snails, tadpoles, and small frogs. These are caught alive and when in motion. 117. Enemies. — As the frog's hind legs are considered a delicacy, man is the worst enemy of the frog. Next come the snakes, birds, and fish. The leech kills frogs by sucking their blood. Fish eat many of the tadpoles, and strange to say, some water beetles eat tadpoles also. 118. Respiration. — Both the skin and a pair of lungs serve to purify the blood of the frog. The air is forced into the lungs by the contraction of muscles in the floor of the mouth. Experiments have been made which show that the frog can get enough oxygen even if the lungs are missing. In this respect frogs resemble worms, which use the skin as the only organ of respiration. 119. Internal Structure. — A study of the parts of the frog or toad should be made for two reasons: (1) To understand the relative positions of the internal organs of a typical vertebrate; (2) to help explain the several organs of man which are discussed in the second part of this book. Digestive Organs. — The mouth is large. Short lips cover the short teeth in the edge of the upper jaw. The 116 AMPHIBIANS tongue has two fleshy horns at the back end and is attached by the front end to the floor of the mouth (Figure 115). The frog can throw its sticky tongue over the tip of the lower jaw and use the forked end to catch insects which are then carried into the back of the mouth. Two groups of little curved teeth in the roof of the mouth aid in preventing the escape of the prey. The food is swallowed whole. The esophagus (the tube Figure 115. — Diagram to Show Organs of Frog. connecting the mouth cavity and stomach) of the frog can be stretched so that a comparative^ large animal can be swallowed. There is no sharp limit between the esoph- agus and the stomach, which is a long spindle-shaped sac (Figure 115), larger than the rest of the digestive tube. The small intestine begins at the back end of the stomach as a small tube which makes several turns, and finally enlarges into a region called the large intestine, the last part of which is termed the cloaca (cl5-a/ca) or common sewer. * Two glands of importance belong to the digestive INTERNAL STRUCTURE 117 organs • the liver and the pancreas. The liver is a large, dark-red, three-lobed organ that covers the ventral (lower) surface of the stomach. The pancreas is a whitish, small, irregularly shaped body attached between the stomach and the intestine. Both of these glands drain into the intestine just beyond the stomach. The bile secreted by the liver is at first collected in a sac called the gall bladder. All of these parts of the alimentary canal are held in place by a thin membrane (the mesentery, mOVen-te'r-y), one edge of which is attached to the dorsal wall along the line of the backbone and the other to the stomach and intestine. A small gland (the spleen') is found in this mesentery. The spleen has no duct connecting it with any other organ in the frog. Blood vessels run through the spleen and scientists believe that it is important in making new blood corpuscles. Lungs. — The lungs are hollow sacs that lie back of the stomach, one on each side. In the freshly killed animal, these can be filled with air by inserting a blow-pipe into the windpipe and blowing air into them. The empty lungs are about as large as the blunt end of a lead pencil. Kidneys. — The kidneys are small red bodies lying close to the back. Each one is connected with the cloaca by a minute duct (ureter). The urinary bladder is attached to the cloaca (Fig- ure 116). Reproduction. — The male frog has a pair of spermaries (speYma-riz), one attached to the front (anterior) end of each Figure 116. // fat bodies ^•testis kidneu -unnogenital duct cloaca 118 AMPHIBIANS nerve to nose Olfactory Lobe - Cerebrum nerve to eye Thalamencephalic^ Medulla ■-•- y Optic Lobe Cerebellum "--Nerve to ear ■ ..4th Ventricle . nerve to arm kidney (Figure 116). Each spermary is yellow in color. The sperms escape through the kidney. In the female frog ovaries, sometimes filled with eggs, are easily seen. A long, closely coiled pair of oviducts (6'vi-dukts) opens in front near the forward end of the stomach and in the back into the cloaca. The eggs break through the wall of the ovary and enter the oviducts. As the eggs pass down through the oviducts, they are coated with a jelly-like covering that swells in the water. This jelly covering pro- tects the eggs. Nervous Syste?n. — The nervous system of the frog is more highly de- veloped than that of the earthworm. It consists of a central part enclosed in the backbone and cra- nium (braincase). This central nervous system in all vertebrates is al- ways found above the Figure 1 1 7. - Central Nervous System digestive tube, and is di- op Prop vided into the brain and the spinal cord, from which numerous nerves arise and extend to all parts of the body. The parts of the brain are the same as in man and much easier to study. Beginning at the front (anterior) end of the brain the parts are as follows (1) : small olfactory (61-fak'to-ry) lobes, which are not sharply marked nerve to leg INTERNAL STRUCTURE 119 off from the rest of the brain, and, as shown in Figure 117, connect with (2) the cerebral (ser'e-bral) hemispheres, which are oval in outline. (3) A short mid-brain region, partly covered by the back part of the cerebral hemi- spheres, connects the front and back part of the brain. (4) Two large optic lobes, the widest part of the brain, are just back of the mid-brain. (5) The cerebellum (se'r-e-bel'lum) of the amphibians is small and easily over- looked (Figure 117). The last region of the brain is the (6) medulla (me-dul'la), which is occupied by a large triangular cavity called the fourth ventricle. The work which each of these regions of the brain does is not sharply defined. The olfactory lobes receive the smell stimuli. The cerebral hemispheres control muscular action. When the latter are removed the frog loses all power to initiate any movement and will sit still in a dry, warm room for hours unless disturbed. This he never does when the cerebral region of the brain is uninjured. The mid-brain region is the passageway for all nerve-path- ways that travel to and fro in the brain. The mid-brain and optic lobes explain to the frog the sight stimuli. In the frog, the cerebellum is less important than in man and is poorly developed. The medulla gives off more nerves than any other region of the brain. Here are found the nerves to the face, tongue, ear, heart, and lungs. While there is a great difference between the shape of the parts of the brain of the frog and those of man, yet the work done by each region is of the same kind. The brain joins the spinal cord, and there is no external sign to indicate where one begins and the other leaves off. A definite number (ten pairs) of nerves leave the brain proper and are devoted to the special senses of the head and to moving the muscles of the throat and head. The frog has ten other pairs of nerves joined to the spinal 120 AMPHIBIANS cord (Figure 117). In a long salamander there are 20 or 30 pairs of nerves on the spinal cord. LABORATORY STUDY In connection with the study of the frog, the following additional lab- oratory work should be done in order that the several organs of man which are discussed in Part II may be better understood. Frogs that have been preserved in formalin can be easily dissected. Examine the digestive organs : first the mouth, then the esophagus, stomach, small and large intestine, and cloaca. For convenience, the liver will have to be removed. The pancreas can be seen as a small whitish structure in the loop between the stomach and the intestine. The spleen is a round, red organ usually found near the large intestine. A pair of narrow kidneys lies close to the back and is connected by ducts with the cloaca. The spermaries are found attached to each kid- ney near the front end and the sperm cells escape to the exterior by the kidney ducts. In the female frog the large ovaries occupy most of the space of the body cavity. A pair of oviducts opens into the body cavity just back of the stomach. The eggs escape from the ovary into the body cavity. The nervous system is enclosed in bone that is easily removed from the dorsal surface. The brain should be studied and the following divisions recognized : cerebral hemispheres ending in front in the olfactory lobes, which are not clearly marked. Just back of these the two large roundish optic lobes which are attached to the midbrain (thalamencephalori) , thal- a-men-ceph'a-lon). The cerebellum is small, and the medulla passes into the spinal cord without any sharp dividing line. 120. Development. — Late in March and early in April the frogs gather in ponds to lay their eggs. The eggs are surrounded by a jelly-like substance which holds them together. As the eggs are being laid by the female frog, the male frog spreads a large number of sperm cells over the whole mass. These sperm cells make' their way through the soft jelly and one of them must enter each egg or it cannot grow into a tadpole. As soon as the sperm cell enters the egg (Figure 119), it begins to change from a solid, pointed body into a round nucleus which is so much like the nucleus already in the DEVELOPMENT 121 egg cell that none but experts in this study can tell which came from the sperm cell and which from the egg cell. These two nuclei come in contact and unite, leaving but Figure 118. — Frog Eggs. one nucleus in the egg (Figure 119). This last change is fertilization, which is defined as the union of the contents of the egg and the sperm nuclei. After this union is completed the egg begins to divide into cells, as shown in Figure 120, and finally a tadpole is grown. Eg'g Nucleus Sperm cell Egg' Nucleus Sperm Nucleus Fused Nucleus Figure 119. — Diagram Illustrating Fertilization in Frog Egg. As soon as the young tadpole hatches, it attaches itself to plants and lives for the first few days upon the food- yolk within its own body ; the mouth forms, and horny jaws develop. Then the tadpole begins to feed upon 122 AMPHIBIANS minute plants and becomes dependent upon its own skill to get food and escape its enemies. For a time the tadpole breathes through gills. Two sets are used. The first ones are on the outside of the body and last for only two or three days, when internal gills form in the throat and the tadpole breathes much like a fish. 121. The Tadpole Be- comes a Frog. — In the growth of the tadpole into a frog the hind legs appear first. Later the front ones begin to show and as they develop the tail is gradually absorbed. While these external changes are going on, there are many complicated internal changes taking place ; internal gills are disappearing and lungs, nerves, blood vessels, and muscles are being formed to give Figure 120. — Dividing Egg of Frog. Figure 121. — Dividing Egg Becoming a Tadpole. the new legs life and action. The internal lungs take the place of the gills in the throat before the legs are fully grown and such tadpoles can breathe only air. Ex- plain in Figure 122 which tadpoles breathe by lungs EVOLUTION 123 and which by gills. This complicated way of growing into a frog is called metamorphosis and this term lias the same general meaning that it did when used to describe tin; growth of insects (page 16). The tadpoles of leopard frogs become small frogs in a single summer, but the tadpoles of bullfrogs and Figure 122. — Two Stages in the Development of Tadpoles. green frogs require two seasons to complete their develop- ment. These latter tadpoles hibernate in the mud with adult frogs and toads. 122. Evolution. — Evolution, in a larger sense, is the theory or belief that all of the complex animals and plants on earth to-day developed from the simpler animals and plants of many generations ago. This theory tries to prove itself through the careful study and investigation of the relationships between animals and plants of the present and those that formerly existed. The study of the changes through which the egg of the frog grows into a tadpole and then into a frog tells us 124 AMPHIBIANS much about the way frogs have developed from fishes. The tadpole breathes and eats like a fish ; but as soon as lungs and legs are formed, it breathes and eats like a frog. This same study of the tadpole also illustrates how ani- mals may gradually have come to live on land. In the early history of the earth there were hundreds of animals and plants which are no longer known to science. The skeletons, foot-prints, and whole bodies of many of these are preserved in the rocks. Such remains are called fossils. If all the animals, or one of each kind, had been pre- served in the rocks, it would be easy to investigate these Figure 123. — Fossil Shells of Animals now Extinct. earlier animals and their relation to the living animals of the present. But in our information there are great gaps, which we are, however, gradually bridging. Apparently unrelated animals have resemblances, so that in time we may come to see that all animals are really related forms, varying only in complexity of structure. One thing that we must always keep in mind is that the plants and animals which live now are but a small fraction of those which have lived. The rocks have preserved the remains of only a small part of the forms of the past. Many of the records HEREDITY 125 of extinct animals and plants have been destroyed by decay and heat so that much that would be valuable in solving the question can never be found. The study of the development of the frog also illustrates two other general subjects, heredity (he-red'I-ty ) and en- vironment (en-vl'run-ment). 123. Heredity. — The tendency of all young animals to grow and live like their parents is called heredity and may be defined as the transmission of physical and mental traits from parent to offspring. There is no difficulty in recog- nizing the new frog as a certain kind of frog. The color markings on the skin are like those of the parents; it grows to about the same size; eats the same kind of food, and lives in the same region. Every species of living thing is able to produce new forms like itself, and heredity is always at work when new plants and animals are being produced. Heredity is best thought of as that quality of living matter which ex- presses itself in the growing plant and animal by making sure that it resembles its parents. Thus heredity deter- mines that leaves of the right shape and size occur in the proper place and that our fingers and thumbs grow on the end of the arm in the usual way. There has been much study of the question of heredity and there is much yet to be learned. However, we know- that we inherit from our parents and grandparents, our complexion, the color of eyes and hair, our size, our re- sistance to disease, our mental traits, and many other characteristics. In 1865 Gregor Mendel, abbot of Briinn, published t la- results of experiments made with peas, which showed thai crossing tall and dwarf peas resulted in all the offspring being tall. But the offspring of these latter (the grand- children, so to speak, of the original peas) might be cither 126 AMPHIBIANS tall or dwarf. The proportions were regular and the re- currence of tall or dwarf peas was so uniform that from these- and other experiments later scientists evolved defi- nite laws of heredity, known as the Mendelian Laws. A detailed statement of these laws is beyond the prov- ince of an elementary book, but it is now well established that certain traits of parent plants and animals are repro- duced in their offspring in regular and definite amounts and proportions. 124. Environment. — This word is used in two ways. First, it refers to general surroundings such as tem- perature, moisture, and seasons, as they vary from year to year ; and secondly, to immediate surroundings. The frog responds to the first by hibernating in the win- ter ; while the second phase of environment may be illustrated as follows : the tadpole can live only in water, and if the pond dries up before the frog stage is reached, the environment has been unsuited to the tadpole. This often happens when the eggs are laid in a temporary roadside pond which evaporates long before the tadpole becomes a frog. All such tadpoles die unless they are able to swim to some other body of water. The birds that are able to fly avoid hibernating in the Figure 124. — Tree Frog. Notice the sticky disks at end of toes. ECONOMIC VALUE 127 winter. They are able to adapt themselves to the change in the seasons without burying themselves in the mud as the frogs do. Some of the birds do not migrate, but remain all winter in the North. They have become so well adapted to con- ditions that they are able to get their food where birds that migrate would starve. Man is the only animal which is able to live anywhere on the face of the earth under the most varied conditions. To realize this fully we have but to think of the different surroundings of the Eskimo, Indian, Bushman, and of ourselves. Each animal and plant is directly dependent upon its environment for food and a home. 125. Economic Value of Amphibians. — The toad is the only member of the amphibian group that is of any great value to man. It destroys many insects. Frogs eat a few but hardly enough to entitle them to high rank as bene- ficial animals. Their chief value is as food and as conven- ient forms for dissection in biology courses. SUMMARY The Amphibians are an interesting group which illus- trates how water animals may have become land animals. The frog has well-developed sense organs, legs modified for jumping, and feet for swimming. The skin is moist and helps to serve as an organ of respiration. The color mark- ings and the habits of the frog serve to protect him from many of his enemies. QUESTIONS What animals belong to this class? How can yon tell them from fish ? Where do the amphibians of your region live? Bow many kinds d<> you know ? 128 AMPHIBIANS See how many kinds of amphibian eggs you can find. How long do tadpoles live before they become frogs ? What do frogs and toads eat? What is fertilization? Metamorphosis? Evolution? Heredity? Environment ? REFERENCES Dickerson, The Frog Book. Hodge, Nature Study and Life. Holmes, Biology of the Frog. Marshall, The Frog. Morgan, Embryology of the Frog. CHAPTER XII REPTILES Figure 125. — A Sea Turtle. 126. Reptiles. — Among the Reptiles (rep'tflz) are in- cluded lizards, snakes, alligators, turtles, and crocodiles. The Reptilia (Latin, repo, to crawl) are char- acterized by a covering of bony plates, or scales, in the skin, by the ab- sence of gills in the adult stages, and by the presence of lungs. 127. Life History. — Unlike the amphibians, the reptiles hatch directly into their adult form, only much smaller. The young snake just out of the egg or the young alligator just hatched is recognized by its resemblance to its parents. There is no meta- morphosis, as in the frog. The reptiles lay their eggs in protected places and exhibit no parental care for the Figure 126. — Horned Toad, a Lizard. Showing egg-capsules in which the young are hatched. eggs or for the young. Some snakes hatch their young in the body of the parent and the offspring are born alive. i If desired, this chapter may be omitted without affecting the sequence in the book. 129 130 REPTILES 128. Turtles. — Turtles are easily recognized by their outer skeleton. This skeleton is unlike the skeleton of the starfish or crab, or of any other group of animals. The Figure 127. — Bull Snake with Hen's Egg in Mouth. skeleton of the turtle, composed mostly of skin plates, is something like a box with a cover, the upper portion cor- responding to the box itself, and the lower portion to the Figure 128. — Bull Snake after Swallowing Egg. cover. The box does not fit closely all the way around, for there are places where the head, the tail, and the four legs stick out. When the turtle is disturbed, the legs, SNAKES 131 the head, and the tail are drawn inside, and the box is pulled down tightly by muscles to meet the cover. The term turtle is often applied to aquatic forms, and the term tortoise to those living on land. Sea turtles attain a length of six or eight feet and weigh Figure 129. — Head of a Rattlesnake. Dissected to show the poison gland, a, and its relation to the tooth. (Duver- moy.) sometimes as much as a thousand pounds. The flesh of the green turtle and of the terrapin (ter'ra-pin) is used for food. 129. Lizards. — There is a great variety of lizards. A common lizard is the chameleon (ka-me'le-un), which has the power of changing the intensity of the color in the skin by moving the color material nearer the outer surface or drawing it away. The horned toad of the Western United States is a lizard with scales of varying length which give it a horny appearance. Horned toads, instead of laying eggs, have the eggs hatched while yet in the oviducts and the young horned toads are born alive. A poison- ous lizard is the Gila (he'la) monster that oc- curs in New Mexico and Arizona. It has the poison glands in its lower jaw. 130. Snakes. — Snakes are legless vertebrates with long, cylindrical bodies covered with scales. They move by means of the scales (scutes) on the under side of the body. Most snakes lay eggs, but a few bring forth living Figure 130. — Rattles of Rattlesnake. 132 REPTILES young. Since snakes eat insects, frogs, mice, rats, and rabbits, they should be considered beneficial. Rattlesnakes1 and copperheads are the most common poisonous snakes of our country. Their jaws are provided with fangs (Figure 129), by means of which a poison is injected into their prey. Large snakes like the black snake or blue racer of the United States, the boa con- Figure 131. — Rattlesnake — -Poisonous. Compare head with snake in Figure 132. strictor of South America, and the python (pi'thon) of Asia are constrictors. They are able to wind their bodies around their prey and to crush it to death. The most deadly snake in the world is the cobra (ko'bra) of India, where thousands of the natives die annually from the bite of this snake. Snakes swallow their food whole, and as the teeth are used merely for holding their prey, they point backwards. 1 The two most common rattlesnakes are the mountain rattler and the massasauge (mas-sa-sa'ge). ALLIGATORS AND CROCODILES 133 Figure 132. — Garter Snake — Harmless. 131. Alligators and Crocodiles. — Crocodiles are found in the Southern United States, South America, Africa, and India. Alligators are found in stagnant pools in the Figure 133. — Eight-foot Florida Alligator. 134 REPTILES Southern States. Crocodiles resemble alligators but have narrower mouths. 132. Adaptations. — Reptiles are peculiarly adapted to their environment. Snakes that live in trees are some- times the color of leaves or bark. Some that are harmless are colored much like poisonous snakes. An adaptive feature of the crocodile is a fold of skin which shuts off the mouth Figure 134. — Alligator Nest. from the throat and prevents water from entering the throat while the crocodile is drowning its prey. The old world chameleons have their feet modified for clasping branches. In the case of the turtles, those that live in the sea have paddle-like feet for swimming, while those that live partly on land and partly in the water have toes with webs. Lizards are almost always of about the same color as their surroundings. SUMMARY 135 SUMMARY The reptiles always use lungs for breathing. They usually have scales or bony plates in the skin and have either two pairs of appendages (turtles, lizards, alligators, crocodiles) or none (snakes). It is important to learn to recognize poisonous reptiles, as their bite is dangerous. Figure 135. — Poisonous Lizards — The Gila Monster. LABORATORY QUESTIONS From models or preserved specimens the difference between the harm- ful and harmless reptiles should be worked out. The living turtle can be studied easily. Its special skeleton is an illustration of protective adapta- tion. Notice how the nostrils of the aquatic turtle can be closed. How- does this help the turtle ? QUESTIONS AVhat are the most common snakes in your vicinity? Are fchey poisonous? How can you tell? Where do they live? What do they eat? How many kinds of turtles do you know? Where do they live? REFERENCES Ditmars, The Reptile Book. Jordan, Kellogg and Heath, Animal Studies. Linville and Kelly, General Zoology. Reese, The Alligator and its Allies. CHAPTER XIII BIRDS 133. Birds. — Birds are the only vertebrates covered with feathers. Their front legs are modified into wings. Among some birds, like the penguins (pen'gwinz) of the Antarctic region, the wings are not used for flying but to assist in swimming. In others, like the eagles and condors, the expanse of the wings is sufficient to enable them to fly away with young lambs and large fish. Between the small wings of the penguin and the great expanse of the wings of the eagle and the condor there are many variations. Bird wings are adapted to the needs of their owners. Sailing birds, like the gulls, have long, slender wings, while ground birds, like the partridge and pheasant, have short wings capable of rapid, short flights. Those birds that make the most use of wings have them best developed. An example of underdevelopment, which has been increased by domestication, is seen in the domestic fowl, a ground bird, which makes little use of its flying powers, and is incapable of sustained flight. The legs of birds also have many variations. In the case 136 Figure 136. — Grebe. BIRDS 137 of the eagles, hawks, and owls there are powerful claws for seizing and holding prey, while ducks and geese have long and webbed toes, adapted to swimming. Seed-eating birds have weak claws which serve merely for perching. Chimney swifts, that spend most of their time in flight searching for food, have well developed wings, and feet used for clinging. Study Figures 139, 140, 149, 155. Figure 137. — Herring Gulls. The beaks of birds show great variation and adaptation for defense and food getting. Hawks, owls, and eagles have the upper jaw curved over, hooked, and adapted for tearing the food; herons and bitterns have the beak modi- fied into a long, pointed weapon of offense and defense ; grosbeaks (gros'beks) and finches have a short, stout beak for crushing seeds and other hard foods; while humming birds have a long, slender beak which in some kinds is curved so that they may reach the bottom of certain flowers. Study Figures 137, 143, 144, 153, 154. 138 BIRDS The birds show a number of other special adaptations which are of use to them. These are hollow bones, a keeled sternum (breast bone), and a high body tem- perature. The skeleton of a bird shows a prominent ridge on the breast bone. This is the keel of the sternum, which serves as a place of attachment for the large wing mus- cles (Figure 139). The lungs of the bird are small, but air tubes extend into the bones, so that the body of the bird is relatively lighter than that of animals with solid bones. Birds lead an active life, which means that they use a great deal of energy. This energy comes from the oxidation going on in the body. In birds, oxidation is more rapid than in other vertebrates, owing to the fact that they almost completely change the air with each breathing movement and thus secure a greater supply of oxygen. The rapid oxidation requires a large supply of food to be digested and assimilated rapidly and it also makes the normal J Figure 139. — body temperature of birds higher than Skeleton of Mal. that of other vertebrates. lard Duck. Figure 138. — Adult Screech Owl. CLASSIFICATION 139 Figure 140. — Different Kinds of Birds' Feet. 134. Plumage. — The feathers of birds show great variety in form and color. In some species there are certain colors which always predomi- nate on the males, while the females have little color ; in other species it is hard to distinguish between the sexes. The brilliantly colored males are supposed to attract the females at the mating season, while the dull colored females are inconspicuous and less likely to be attacked by enemies while hatching their eggs, or caring for their young. We may say, therefore, that they are protectively colored. The color of birds varies during the first two or three years of life. 135. Classification. — Birds are usually di- vided into groups ac- cording to their struc- ture. The shape and size of the beak and of the feet and wings are the characteristics most used in the general classification. This is illustrated by a single Figure 141. — Loggerhead Shrike. group of birds, the 140 BIRDS Figure 142. — Young of Red-tailed Hawk — Beneficial. hawks, owls, and vultures, which are given the technical name of Raptores (rap-t5'rez Latin, rapere, to ravish), birds of prey. The bird books describe the Raptores as Figure 143. — Head of Young Eagle. CLASSIFICATION 141 follows: toes four, three in front and one behind, except in the vultures ; all toes armed with strong, sharp, curved talons (tfil'iinz); bill with a cere (ser : Latin, sera, wax) or covering of skin at its base through which the nostrils open, very stout and strong, the upper mandible tipped with a sharp pointed hook. In addition to this classification by structure, which is essential for a careful study of birds, they are also classi- fied by their habits. For example, birds are divided into four classes based on their migratory habits. Birds like the downy woodpecker and English sparrow are permanent residents throughout their range, that is, they can be found within given limits at any time of year, while bobolinks and humming birds are summer residents, mi- grating southward at the end of the season. Birds like wild geese, fox sparrows, and the like, arc transients, stopping along their migratory route for rest or food or to escape unfavorable weather; while such birds as the snowy owl, great northern shrike, and red- poll are winter visitants which have migrated to us from the North when the cold became excessive and the food supply diminished. Birds are classified also by their nesting habits. Some birds, like the meadow lark and bobolink, nest in the open field, and their nests are made inconspicuous rather than inaccessible; other birds, like certain hawks and eagles, Figure 144. — The Robin. Sometimes a winter resident. 142 BIRDS Figure 145. — Nest of Goldfinch. Nest of altricial bird. build their nests in tall trees, making them conspicuous, but inac- cessible. Still others build like the oriole at the end of slender branches where they are out of reach of animals. Birds like the kingfisher, sand swallow, and puffins build their nests at the bottom of a burrow in the ground. 136. Nest Building. — Birds show great variation in nest building. Some build a large nest with materials loosely put together; others build small nests of neatly woven material, and some birds, like cowbirds, build no nest at all, but lay their eggs in the nests of other birds and leave the work of caring for their young to the foster parents. The number of eggs that birds lay in their nests varies from one to as many as thirty or forty. The time required to hatch the eggs varies from ten days to six weeks. Birds whose eggs hatch in ten days or two weeks are called al- tricial (al-trl'shal : Latin, altrix, nurse), for such young are hatched helpless, blind, Figure 146. — Nest of Least Bittern. MIGRATION 143 and with little down. Eggs that hatch in from three to six weeks develop well-formed young, able to run around within ten to twelve hours after hatching. These are known as prcecocial (pre-ko'shal : Latin, prae, before; coquere, ripen). Such birds have little need for a sub- stantial nest and few of them build one. The robin is Figure 147. — Mourning Dove. altricial, and the domestic fowl prsecocial (Figures 1 |.~> and 146). 137. Migration. — Because they are provided with wings and the power to fly long distances, birds are able to move from one region to another for the purpose of finding food and rearing young. The precise cause of migration is still unknown. Birds in general migrate to a warmer climate in the fall of the year and return to the cooler region in the springtime. In some cases birds cross the equator in migrating. For example, the bobolink nests in 144 BIRDS the Northern United States and passes the winter in South Amer- ica, migrating a distance of over five thousand miles. In the case of the robin the migration is limited to a short flight to the south to some protected swamp provided with water and food. A probable cause of migration is the fail- ure of food supply as cold weather comes on in the fall. 138. Economic Impor- tance of Birds. — The chief food of birds is insects, such as plant lice, larvae of beetles, butterflies, moths, borers, etc. The chickadee, for example, feeds on plant lice as well as other foods ; the downy woodpecker feeds on codling moths and borers ; the nuthatches and brown creepers feed on insects and insect eggs that are hidden in crevices and under loose pieces of bark. Other useful birds are the song sparrow, chipping spar- Figure 148. — Chimney Swift and Nest. Part of the birds have been crowded out. row, robin, bluebird, Figure 149. — Junco. A transient bird nesting in Canada, and on the high hills and mountains of the Northern states. ECONOMIC IMPORTANCE 14.-) Figure 150. — Female Bobolink. wren, blackbird, etc., which feed principally on insects that are found on or near the ground. The insects that fly, like mosquitoes, gnats, and house flies, are eaten by swifts, swallows, night hawks, king birds, and fly catchers. Among the hawks and owls is found a long list of beneficial birds, for the screech owl, red-tailed hawk, and the red-shouldered hawk are almost without excep- tion valuable as destroyers of shrews, moles, mice, rats, weasels, and rabbits. The hawks that are partly harmful are the sharp-shinned hawk, Cooper's hawk, and the marsh hawk. All of these help themselves to poultry and feed on small beneficial birds like the song sparrow and bluebird. The exact relation of birds to agriculture and the foods that they cat has been a subject of study by the Depart- ment of Agriculture. Fisher reports the fol- lowing' results in his analysis of the stomach contents of 220 red- shouldered hawks : ;,» of them contained poultry, Figure 151. — King Bird. 12 of them held 102 146 BIRDS Figure 152. — Young Crows in Nest. mice, 40 of them other mammals; 20 of them reptiles; 39 of them amphibians ; 92 of them insects ; and 16 of them spiders. A similar analysis of 133 stomachs of Cooper's hawks shows the following : 34 of the stomachs contained poultry or game birds, 52 contained other birds ; 11 of them mammals ; 1 of them a frog ; 3 of them lizards, 2 of them insects, while 39 of them were empty. Aside from being of value in the destruction of insects, birds destroy waste matter and dead Figure 153. — Kingfisher. animals lying Oil the ECONOMIC IMPORTANCE 147 ground. The vultures and buzzards of the South and West eat dead animals. The gulls of the sea and lakes destroy refuse thrown upon the sur- face of the water. The eagle is also a scavenger as it eats dead fish that float on the surface of the water, or small dead animals thrown out in the open on the land. Crows also eat dead fish. There is also a group of birds that lives largely on seed, and such birds destroy vast amounts of weed seeds. Among the seed eaters are the quail, grouse, pheasant, goldfinch, sparrows, bobolink, and meadow lark. A Figure 154. — Hairy Woodpecker Eating Suet. Figure 155. — Male and Female Cowbirds. 148 BIRDS — -e- • /I?" • -,//>-J\y f-*\ OD Kind of Food I. Ill IS W'lNTKK Life in Si mm Kit I'.l M II' 1 \l II u:\li ii are useful as food, companions, beasts of burden, and for clothing. The furs of wild animals and the leather and the wool of domestic animals are most important in protecting the body of man from unfavorable weather. Among the domestic animals the horse is useful for driving and draught work, and the cow for its flesh, milk, and butter. The sheep, through its flesh and wool, is an economic factor of great impor- tance in civilization. There are harmful mammals like gophers (go'ferz), prairie dogs, rabbits, rats, and mice. Lions and tigers some- times kill human be- ings. Weasels, skunks, and mink are often harmful in poultry yards. Figure 171. — Elk. 156 MAMMALS Figure 172. — Virginia Deer. Figure 173. — Fawns of the Virginia Deer. ECONOMIC IMPORTANCE 157 Figure 174. — Coon. Figure 175. — Young Woodchucks. 158 MAMMALS Figure 176. — Camel. The Ship of the Desert. In making long trips across the desert, the camel is able to go without drinking. During these journeys, the hump grows smaller as the fat in it is used as food. This food is gradually changed until part of it be- comes water. We might say that the fat in the camel's hump is a special water reservoir. Figure 177. — Buffalo. These sturdy animals once roamed the plains in great numbers. were not protected in park preserves, they would now be extinct. If they SUMMARY 159 SUMMARY The animals which are called mammals are covered with hair, and nourish their young with milk. There are nearly always two pairs of appendages that undergo much modi- fication according to the habits of the animals. ( )ur domestic animals which serve us in so many ways have grad- ually developed into their present form and usefulness. Man had to learn first how to use the fur and skin of wild animals, then how to improve the quality of the fur and skin by careful feeding and breeding of the domesticate! animals. FIELD SUGGESTIONS If you are where you can visit a Zoological park it is an easy matter to learn how to distinguish the different nianimals, a thing which every one should be able to do. There is another line of study which consists in selecting some one or two of the common mammals, such as squirrels, and making a thorough study of them from week to week, month to month, year after year, until you feel thoroughly acquainted with them. A third line of study is that of hibernation. Some mammals do not hibernate, some do so only during cold snaps, while others go to sleep for the entire winter. QUESTIONS How do you tell a mammal from other vertebrates ? What mammals live near your home ? What do they eat ? Where do they spend the winter ? REFERENCES Davenport, Domestic Animals and Plants. Linville and Kelly, Zoology. Plumb, Types and Breeds of Farm Animals. Stone and Crane, American Animals. PART II HUMAN BIOLOGY CHAPTER XV LIPE PROCESSES OF MAN 142. Adaptation. — Adaptation includes all the variations in structures and habits which have been formed by an animal or plant to enable it to live in its own particular environment. Thus certain forms are adapted to living in the tropics, others in the temperate regions, and still others in the arctic regions. Living things which can adapt their lives to our northern winters do not need to migrate south as cold weather comes on in the fall. The frog cannot migrate, but hibernates in the mud. Man is the best adapted of all animals to live in all parts of the world. When and where man began to live on the earth is not accurately known, but it was many thousands of years ago. He has been able to spread over the face of the earth because he can control his surroundings, that is, if he happens to live where there are many enemies, he in- vents destructive weapons and kills his enemies or drives them away. This is true even of disease, — man's greatest enemy. Again, most animals are either flesh-eating or plant-eating, but man is both, and because he lias learned to eat a greater variety of both kinds of food than any other animal, it is easier for him to live and to raise his children in all climates. 161 162 LIFE PROCESSES OF MAN All of the animals so far studied have been able to live only in their own limited surroundings. The grasshopper, the earthworm, the paramoecium, and the crayfish are not found in the sea or arctic regions. If the paramoecium or the crayfish is placed in sea water, where the lobster and many unicellular animals live, it dies. On the other hand, if the starfish or some of the seafish are placed in fresh water, they die. All of these animals are adapted to their own limited surroundings. Scientists give four reasons in explaining why animals and plants are not adapted to live in all parts of the world: (1) lack of suitable food ; (2) failure in adapting their lives to the peculiarities of climate ; (3) too many enemies ; (4) inability to raise their young. STUDENT REPORT The following table points out some of the common adaptations in animals. How are they related to the animal's success in life ? Name some other habits which help to protect animals. Home Protection 7. 2, 'SI W H Z o z H c (J Z (—1 o Eh w J w S5 -4 fa Z z H n 1-1 o > M W l-t P H fc H ■- 63 W OS o "4 z 03 w o o H Eh H a -sj 05 X © >■ _! H Eh Q O < £ M •A < © K W < < W < * fe ft o W a Earthworm .... Grasshopper .... ■ English Sparrow . . , Bog YOUTH, MATURITY, OLD AGE 163 143. Youth, Maturity, Old Age. — The life of man is divided into three general periods, which are youth, the period of maturity, and the period of old age. These same terms are given when describing the life of animals and plants. Youth is the period when living protoplasm always grows, if furnished with proper food. This is the time when boys and girls grow taller and heavier each year ; when the tree grows new leaves and the limbs become longer; and when the small puppy is turning into a full grown dog. During this period of change the boys and girls, the tree, and the puppy are all nourished by food and this makes it possible for them to grow. Maturity is the period when man ceases to grow taller, although he con- tinues to eat food as he did during the period of youth. The living proto- plasm in his body does not increase in amount. The same can be said of the tree, for it does not grow taller ; and the puppy of last year has become a full grown dog. During this period Figure 178. — Ali- mentary Canal of Frog. Compare with Fig- ure 179. In what are they alike? In of maturity, each living organism is what different? able to repair its body as fast as the body wears out. The period of maturity varies in all living things ; in some butterflies lasting but twenty-four hours, in man continuing for about twenty-five years. Old age in man begins when the bodv wastes faster than it is repaired, and in the tree when growth Is over and decay begins. During this period of old age all living things use food as they did in youth and maturity, 164 LIFE PROCESSES OF MAN but the body wastes faster than it can be repaired and death is the final result. Old age occurs at different ages in different individuals ; and the same is true of animals and plants. STUDENT REPORT Fill out the following table and describe the digestive system of the animals studied thus far in Part I. This will help you to understand better the parts of the digestive system of man and the work that each part does. Paramo3cium Hydra Earthworm Frog Man Etc. One Cell Man y Cells No Digestive Tube Digestive 'iUBE No Well Defined Digestive Glands Which Ones Require Food ? 144. Digestive Organs. — The digestive organs of man consist of the same parts which have already been described for the frog. Each region of the digestive organs is more perfectly developed and the biological principle, the di- vision of labor, readies its highest -development in man. The parts of the alimentary canal in man are : the mouth, containing the teeth, tongue, and glands ; the throat or pharynx; the esophagus, the stomach, the small and the large intestine. The last part of the large in- testine is called the rectum. These several parts form a continuous tube, and each does a particular work in di- gestion (Figures 178 and 179). The mouth is lined with a soft membrane, kept moist by the saliva secreted by three pairs of glands, and poured THE DIGESTIVE ORGANS if..-) tongue bladder oesophagus stomach into the mouth in sufficient quantities to moisten the dry food and thus assist in swallow- ing. The tongue is a muscular organ and bears on its upper surface many small fleshy pro- jections called papillae (pa- pil'le : Latin papilla, bud), some of which are fairly large and are arranged on the back of the tongue in the form of a V (Figure 180). Our power to taste sweet, sour, bitter, and salt, which are the four fundamental tastes in man, is due mainly to certain nerve cells located on the larger papillae. The food stimuli received by the special sensory cells of the papilhe are carried to the brain by the taste lar$e intestine pancreas small intestine appendix Figure 179. — Alimentary Canal of Man. I I l Figure 180. — Tongue. Figure 181. — Taste Cells. The taste nerve ends among these cells. 166 LIFE PROCESSES OF MAN nerves. In the brain the food stimulus is interpreted as sweet, sour, or bitter (Figure 181). LABORATORY STUDY Blindfold in turn several members of the class and have each hold his nose while a small amount of some highly flavored food is placed on the tongue. Such common foods as maple syrup, vanilla extract, marmalade, jams, etc., are admirable for this test. Make a record of each test. This experiment will prove that we do not taste flavors. Remove the hand from the nose and again taste the same substances. This time there will be no difficulty in telling the name of the substance because it has been smelled as well as tasted. The roof of the mouth is called the palate. The front part contains supporting plates of bone and is therefore called the hard palate. The back part (the soft palate) is a thin sheet of muscle covered by the mucous lining of the mouth. The palate separates the mouth from the nasal cavity. Beyond the soft palate is the throat cavity called the pharynx. This is a funnel shaped cavity, having two openings at its lower end, the front one being the opening into the windpipe which leads to the lungs, and the rear one, the opening into the esophagus. In the upper part of the pharnyx on each side, is the opening of an eusta- chian (u-sta/ki-an) tube which passes to the middle ear. Teeth. — Just back of the lips are the teeth. In adults there are thirty-two, sixteen in each jaw, belonging to four classes according to shape. In front are the eight incisors (in-si'zers) with sharp cutting edges ; next the Figure 182. — Milk Teeth. Age 2>\ to 4 years. Notice the per- manent teeth deeper in the jaws. THE DIGESTIVE Olid ASS 16! four sharp-pointed canines (ka/nins), aiid back of the canines the eight pre-molars (pre-mo'lers) Bhaped for tearing and crushing, while the remainder of the teeth, twelve in number, are the flat-topped molars which do most of the grinding of the food. Care of the teeth. — We all know that the teeth are hard. That, however, does not prevent them from becom- ing broken by carelessness or accident, or from decaying because of neglect. When the teeth are not cleaned, a substance called tartar forms on them, which prevents the bacteria from being rubbed off and sometimes pushes the gums away from the teeth. The bacteria cause food particles to ferment and form acids which dissolve the hard outside covering (enamel) and then rapidly the softer parts of the teeth. This re- sults in toothache, a foul breath, and the im- perfect chewing of the food. The teeth should be brushed after each meal to remove particles of food and particu- larly sugar which ferments easily. At least once a year there should be a visit to the dentist who will remove those portions of teeth that are decayed and will lill cavities, thus preventing further decay of the teeth. The value of good teeth cannot be overestimated. The esophagus is a nearly straight tube connecting the mouth with the stomach. It passes through the diaphragm (Figure 208), enlarges, and becomes the stomach. As soon as one swallows, control of the food is lost, and further action becomes involuntary. Two sets of Figure 183. — Permanent Teeth. His LIFE PROCESSES OF MAN Figure 184. — Pear- shaped Human Stomach. muscles, one extending lengthwise, the other around the esophagus, act together in forcing the food or water into the stomach. This explains why we can drink from a brook when the head is much lower than the stomach. Stomach. — In man the stomach is the largest section of the digestive tube, and it has a capacity of about three pints. It is usually described as pear-shaped although there is much variation in its form (Figures 184 and 185). At the point where the esophagus joins the stomach there is a muscular ring (cardiac valve, kiir'di-ak) which ordinarily prevents the food from passing again into the esopha- gus. In vomiting, this valve becomes relaxed. The opening at the larger and lower end of the stomach is guarded by a similar valve (pyloric, 23i-16Vik) which serves to retain the food in the stomach until certain digestive changes have taken place. The intestine has two parts, a small, much coiled tube about an inch in diameter and about twenty feet long called the small intestine; and a large section about five feet long and four inches in diameter, bent in a rough p shape and called the large intestine. At the junction between these two miliar to physicians regions projects a short sac, the vermi- and is called the J_ ■p y s ~- i' « j.* „ , shape. — Dr. C. F. jorm appendix (vermi-form ap-peiv- potter. diks). The disease called appendicitis (ap-pend-i-si'tis) affects this organ. The large intes- tine ends in a special region called the rectum. The Figure 185. — X-ray Photograph of Human Stomach. FOOD im Figure 186. — X-ray Photo- graph of Appendix and Part of Large Intestine. The constrictions are natural. opening of the rectum to the outside is the anus (a/ntts). Glands. — A gland is a group of special cells which secrete a fluid. The glands which pro- duce the digestive fluids are (1) the three pairs of salivary (sal'i-va-ry) glands, located below the ear, and beneath the tongue and lower jaw ; (2) the numerous gastric (gaVtrik) glands found in the lining of the stomach, possibly 5,000,000 in number (Figure 187) ; (3) the pancreas; and (4) the liver, the largest gland in the body. 145. Food. — One of the best definitions of food is the following. Food is that which when taken into the body builds up tissue or yields energy. All organic foods or foodstuffs are divided into three classes, the proteins (pro'te-ins), the cdrhoh yd 'rates (kar-bo-hi'drats), and the /ate. This classi- fication is made whether we studv the foods of a plant, an animal, or of man. Scientists are able to tell to which class meat, bread, oatmeal, milk, and all other foods belong by finding out the chemical composition of each. The chemists have made a thorough study of food and tell us that certain chemicals are present in each of the three classes of foods. Defi- nite chemical tests tell us to which of these three classes any given article of food Figure 187. — \ ° . _ . Gastric Gland belongs. In general it may be said that the 170 LIFE PROCESSES OF MAN proteins are necessary for the growth and the repair of the bodv, and that the carbohydrates and fats furnish heat to keep the body warm, and energy for muscular work. The unused fat is stored up as fatty tissue. All classes of food are found in the various foods obtained from plants. Some, like honey, are nearly pure carbohydrate, while the English walnut contains, in addition to fat, a large quantity £t^3^'"«~^- v3"'^r*0 > ;-=?cj * Figure 188. — Microphotograph of Stomach. The stomach is an organ composed of several tissues arranged in layers. The gastric glands are in the innermost ragged layer and look like rows of black dots. of plant protein. Animal foods can furnish us with only proteins and fats. In primitive times man used a re- stricted diet and led an active out-of-door life. To-day man is living on a mixed and varied diet. This is to be regarded as an acquired habit and one that is questionable when carried to an extreme. The question of how much to eat is a modern problem, and on its solution depend our health, length of life, and energy for work. Thomas Henry Huxley (1825-1895) was a celebrated English biologist. As a young man he made a trip around the world in H.M.S. Rattlesnake, which was on surveying service in Australasia. On reluming home Huxley devoted himself to the study of biol- ogy. He held a number of important academic positions and was made President of the Royal Society in 1883. Huxley was one of the most laborious workers in biology. He rearranged the animals in new classes and discovered remarkable similarities in their development. He is celebrated for his theory of protoplasm and for his able advocacy of the views of Darwin. Huxley showed great skill in putting the conclusions of science into simple language. DIGESTION 171 STUDENT REPORT Animals eat a large variety of things, parts of which serve to furnish energy or to nourish the body. In the following report, work out the sources from which the animals derive their food. To what extent ;ue they alike ? Para- mecium HVDUA Earth- worm Frog Man Flies Minute plants . . Minute animals Flies Add food of man . 146. Digestion. — Digestion begins in the mouth. The teeth break up the food and mix it with the fluid of the mouth, the saliva. During this process, sugars and starches are changed into soluble sugars. The fluids of the mouth are usually slightly alkaline (al'ka-lm or lin, a chemical term, the opposite to sour or acid), but as soon as the food passes into the stomach it enters an acid (sour) medium, and the digestive action of the saliva is destroyed in a short time by the stomach fluid. For this reason, the sugar and starch undergo no further digestive changes until they reach the intestines. Into this acid medium of the stomach, the gastric glands (Figure 179) pour out the gastric juice (a digestive fluid), and the pepsin in this juice acts on the proteins so that they can later pass through the walls of the intestines. In the stomach the heat of the body dissolves some of the fats into oils, but many of the fats used as food remain solid at body temperature and are unchanged in 1 lie stomach. After one or two hours the food passes into the intes- tine and undergoes further changes in another alkaline medium. Here the pancreatic juice, which is made in the 172 LIFE PROCESSES OF MAN pancreas, comes into contact with the digested and partly digested food, causing three different changes. One is to complete the change of proteins into simpler products ; a second is to finish converting starches into sugar ; while the third is to assist the bile (the digestive juice made in the liver) to digest the fats. The digestion of the food is practically completed in these three regions of the diges- tive tube, although digestion continues to some extent after the food is passed into the large intestine. The pepsin in the gastric juice is called an enzyme (C'li'zim: Greek enzymos, fermented) or ferment. There are three different enzymes in the pancreatic juice, none in the bile, and one in the saliva. These enzymes are the chemical bodies which digest food. All plants and animals digest their food by means of enzymes. Inorganic foods, such as water, oxygen, and salts, man takes into his body, making them part of his living pro- toplasm, or using them in oxidation. There is a large amount of water in man, enough to make up nearly two- thirds the total weight of his body. AH of his food con- tains water. / STUDENT REPORT Where the Food is Digested In the Cell In the Leaf Primitive Digestive Tube Stomach Mouth Digested by Enzymes Paramecium . Hydra . . . Frog .... Man, etc. . . Bean .... Yeast .... Teacher may explain yeast and bean to help out the comparison. ABSORPTION OF FOOD L73 Oxygen is breathed in from the air, and the various Baits, such as common salt, sodium chloride (so'di-um kld'rid, or rid), calcium (kal'si-um), magnesium (lnag-nf-'/.hi-um, or -shi-),jP0ta$8iM??i(po-tas'si-um), and phosphorus (fos'fBr-US ) are taken in with our food. They are useful to the body. A small amount of iron is also contained in food and water and becomes a part of the red blood cells. LABORATORY STUDY Study food and food tests. Artificial gastric juice is easily prepared "by taking | gram of pepsin, Taff cc. of strong hydrochloric (hi-drft-klo'- rik) acid and adding 50 cc. of water. Take white of egg that has been cooked and subject it, in a test tube, to the above mixture. A variety of tests should be made, with and without heat (100 F.) with and without the acid. Pancreatic juice is made by uniting 15 grains sodium (so'dl-fim) carbonate (kar'bon-at), 5 grams pancreatin (pan'kiv-a-tin), and 100 cc. water. The action of this fluid may be tested as above on the fata, as ■olive oil ; on starch, as flour ; and on proteins, as raw lean meat or milk. Also examine several of the common articles of food to determine to what •class of foodstuffs they belong. 147. Absorption of Food. — The absorption of food in man .and animals is the process of taking the digested foods from the alimentary canal into the blood. Practically no food is absorbed in the mouth or esophagus, and but little in the stomach. The absorption of food from the intestinal canal is done by small folds in the lining of the small intestine. To the naked eye, these folds appear as a covering of minute hairs, called villi (villi). Their structure is shown in Figure 189. The process of osmosis, which has been so frequently referred to in Part I, is the chief factor in the passing of the food into the blood vessels. This process is assisted by the action of the livinsr cells in a manner not well under- stood. 174 LIFE PROCESSES OF MAN The digested proteins and sugars pass directly into blood vessels which lead to the liver. In the liver, these blood vessels unite to form the portal (por'tal) vein, which is divided into minute branches that distribute the blood to the cells of the liver. As the blood thus passes among the liver cells, the larger part of the sugar is changed into glycogen (gli'ko-jen), an animal starch, and stored tempo- rarily in the liver cells. This stored-up starch is given out gradually and changed urn /esse! lph or vessels Wall \of Irtres+ine back into sugar, which re- sults in keeping a uniform amount of sugar in the blood. The fats pass into certain distinct vessels, lacteah (lak'- te-als), which in turn open into larger ones. Eventu- ally these vessels unite to form a large duct — the thoracic — which empties into one of the veins near the heart. The food is now in the blood stream and is carried to the individual cells of the body. Each cell takes the kind of food which it needs and bv a series of changes, as yet only partly known, makes the food into living protoplasm. The indigestible part of the food is not absorbed, but continues to move through the small intestine into the large intestine, and on through the rectum. During this progress much moisture is absorbed, especially in the large intestine, which leaves the " undissolved food " harder and harder. The regular removal of the unused part of Figure 189. — Diagram of Villus. ABSORPTION OF FOOD L75 the food, faeces (fe'sez), is of much importance in main- taining health, because the bacteria living in the digestive tract cause the waste material to decay and fche poisonous substances thus formed are injurious when absorbed into the blood. Foods normally remain in the stomach from one to five hours, and in the small intestine about four hours; while they may be from six to twenty-four hours in passing through the large intestine. We become hungry each day and feel re- lieved only after eating. A person frequently eats a large meal because of an extra amount of work that is to follow. But is he helped to do the extra work ? Probably not, for the strength to do the work of to-day comes from the food eaten yesterday, or possibly the day before yesterday. The food, even after digestion is com- pleted, must pass through many changes before it is built up into protoplasm. The actual building of the food into protoplasm is the process for which the word nourishment is used, and it should not be confused with absorption. Water. Figure 190. — Home-made Apparatus to show Osmosis. Food as purchased contains Edible portion e.g., flesh of meat, yolk and white of eggs, wheat, flour, etc Nutrients Protein. Fata ( Sarbohydrafe 9. Mineral mat; Refuse e.g., bones, entrails, shells, brain, etc. 176 LIFE PROCESSES OF MAN Alcohol is made up of carbon, hydrogen, and oxygen. All proteids contain nitrogen in addition to these three. Because alcohol contains no nitrogen, it cannot be used as a food to build up tissue. All serve as fuel to yield energy in the form of heat and muscular power. USES OF NUTRIENTS IN THE BODY Protein Forms tissue e.g., white (albumen) of eggs, curd, casein (ka'se-m) of milk, lean meat, gluten of wheat, etc. Fats Are stored as fat e.g., fat of meat, butter, olive oil, oils of corn and wheat, etc. Carbohydrates Are transformed into fat e.g., sugar, starch, etc. Mineral matter (ash) Shares in forming boner e.g., phosphates of lime, assists in digestion, etc. potash, soda, etc. Comparative amount of food required for persons of various ages and conditions, taking as the unit, the amount of food required by a man at moderately active muscular work : Man at hard muscular work requires 1.2 the amount of food of a man at moderately active muscular work. Man with light muscular work or boy 15-16 years old requires 0.9. Man at sedentary occupation, woman at moderately active work, boy 13-15, or girl 15-16 years old requires 0.8. Woman at light work, boy 12, or girl 13-14 years old requires 0.7. Boy 10-11 or girl 10-12 years old requires 0.6. Child 6-9 years requires 0.5. Child 2-5 years old requires 0.4. Child under 2 years old requires 0.3. Heat is a form of energy and one of the reasons for taking food is to keep up the supply of this energy. The more work a person does the more energy he uses, but even a resting body uses some energy, 'for the heart beats and the muscles of the chest move. The amount of PREPARATION OF FOOD 177 this form of energy a person uses is measured by a unit of heat named the calorie (kal'6-ri). A calorie represents the amount of heat required to raise the temperature of a pint of water about four degrees Fahrenheit. A man in rising from a chair, walking eight feet, and returning uses about one calorie. Pecuniary Value of Food. — The table on page 178 from the government bulletin helps to give students an appre- ciation of the relative cost and value of the more common foods. 148. The Preparation of Foods. — Some foods, such as milk, fruit, and nuts, may be eaten without being cooked. but most of our food has to undergo this process before it is suitable for eating. As no two kinds of vegetables or meat are best cooked in exactly the same way, attention should be given to the preparation of food for the table. Successful cooking accomplishes four ends. (1) Changes are brought about to make the food more digestible, such as softening or dissolving it. (2) The nutritious parts are carefully saved. (3) Certain amounts of the three classes of foodstuffs are selected in order that all the chemical elements which the body needs may be supplied. This is known as a "balanced ration." (4) The food is made attractive in appearance and taste, "good to eat." Every woman who wishes to have a happy, healthy family should make a serious study of cooking. Many of the facts about the nutritive elements which foods contain, and the many changes which they undergo in cooking are found out by chemists who study them in laboratories. It is not necessary for all of us to know all these facts. but a good cook follows the rules and recipes which have been made as a result of scientific laboratory studies. To illustrate how much is involved in cooking, let us 178 LIFE PROCESSES OF MAN Comparative Cost of Digestible Nutrients and Energy in Dif- ferent Fooi> Materials at Average Prices1 It is estimated thai a man at light to moderate muscular work requires about 0.23 pound oi protein and 3,050 calories of energy per day. a y. p o Ph C4 Amounts for 10 Cents KlM> OF Material © s Weight i) Ma- z ■n S > H P — z \ \ z ~ Z < Total of Foe TERIAL H O < C < < > w — o M W r, nts Dollars Cents Pou nds Pounds Powids Pounds Calories 25 1.60 25 0.40 0.06 0.06 — 410 1(5 .87 18 .63 .11 .08 — :.oo Beef, shoulder clod . . . 12 . i.» 17 .83 .13 .OS — 595 Beef, stew meat 5 .35 7 2 .29 .23 — 1,530 Beef, dried, chipped . . . 25 .98 32 .40 .10 .03 — 315 Mutton chops, l<»iii .... 16 1.22 11 .03 .08 .17 — 890 20 1.37 22 .50 .07 .07 — 445 12 .92 10 .S3 .11 .19 — 1,035 Pork, Bmoked ham . . . 22 1.60 13 .45 .06 .14 — 735 12 6.67 3 .S3 .02 .OS — 2,950 < lodfish, dressed, fresh . . 10 .93 46 1 .11 — — 220 Halibut, fresh 18 1.22 38 .56 .08 .02 — 265 i .45 22 1.43 .22 .01 — 465 Mackerel, salt, dressed . . 10 .74 9 1 .13 .20 — 1,135 Salmon, canned 12 .57 13 .83 .IS .10 — 760 ( >\ sters, 35 1 per qt. . . . 18 3.10 80 .56 .03 .01 .02 125 Lobster, canned IS 1.02 46 .56 .10 .01 — 225 30 30.00 9 .33 — .27 — ■ 1,125 Eggs, 86^ per doz 24 16 2.09 .64 39 8 .42 .63 .05 .16 .04 .20 .02 260 1,185 Milk. T c per <(t 3A 1.09 11 2.S5 .09 .11 .14 s>5 3 .31 ••> 3.33 .32 .03 2.45 5,440 Corn meal, granular . . •-'A .32 2 4 .31 .07 2.96 6,540 Wheat breakfast food . . . T§ .73 4 1.33 .13 .02 .9S 2,235 < >at breakfast food .... >i .53 4 1 33 .19 .09 .86 2,395 4 .29 2 2.50 .34 .16 1.66 4,500 8 1.18 5 1.25 .08 .97 2,025 Wheal bread 5 .04 4 2 .16 .02 1.04 2,400 5 .65 4 2 .15 .01 1.04 2,340 Beans, white dried . . . 5 .29 3 2 .35 .03 1.16 3,040 2* 2.0S 22 4 .05 .01 .IS 460 6.65 77 2 .02 — .05 130 10 4.21 23 1 .02 .01 .18 430 Potatoes, 60 p per bu. . . . 1 .67 3 10 .15 .01 1.40 2,950 1 1.33 8 10 .08 .01 .54 1,200 U 5 00 8 6.67 .02 .02 .65 1,270 T 10.00 27 1.43 01 .01 .IS 370 6 12.00 4ti 1.67 .01 — .13 250 7 8.75 47 1.43 .01 .01 .09 215 G — 3 1.07 — — 1.67 2,920 1 Principles of Nutrition and Nutritive Value of Food, W. C. Atwater, Farmers' Bulletin No. 1 I-.'. *The cost of 1 pound of protein means the cost of enough of the given material to furnish 1 pound of protein, without regard to the amounts of the other nutrients present. Like- wi-e the cost of energy means the cost of enough material to furnish 1,000 calories, without reference to the kind> and proportions of nutrients in which the energy is supplied. These estimates of t he cost of protein and energy are thus incorrect in that neither gives credit for the value of the other. PREPARATION OF FOOD 179 see what it means to produce a loaf of wholesome bread. Flour contains much starch, some sugar, some mineral substances known as phosphates, a large quantity of gluten (a protein), and some bacteria (tiny plant-, see Chapter XXIV) which may or may not be of value in making bread. When water is added to the flour, it becomes tough and sticky, this being a characteristic of gluten, and the most important one, so far as tin- making of bread is concerned. A small bit of yeast (a small plant, see Chapter XXIV) is added to the water used in making bread, and the dough is placed where it will be neither too hot nor too cold (70°-80° F.). The yeast begins to grow rapidly, feeding on the proteins of the flour, and as the yeast grows, it acts od the sugar. A substance called zymase (zim'as), secret ed by the yeast plant, breaks the sugar up into carbon dioxide, alcohol, and a small quantity of glycerin. The gas tries to escape, but is held in by the sticky dough. If the yeast plant is well distributed, the gas collects in many small bubbles, and the loaf is fine-grained. The alcohol keeps other plants from growing there, and also helps to soften the gluten. When the loaf is put into the oven, the heat kills the yeast plant, drives off the carbon dioxide, and causes the alcohol to evaporate. The heat changes the gluten into a substance more easily digested and of a more pleasant taste. In "salt rising' bread bacteria from the air, instead of yeast cells, form the gas which makes the bread light. When a batch of bread "sours," it is usually because harmful bacteria get into the dough ami grow more rapidly than the yeast plants. Sometimes other kinds of yeasts than the helpful ones employed in bread-making accidentally get into the batch of bread and it spoils as a result. 180 LIFE PROCESSES OF MAN 149. Adulteration of Foods. — Foods are adulterated either by subtracting some of the nutritious parts and substitut- ing less valuable parts, or by adding materials which can- not act as a food. The food formerly subject to the most adulteration was milk. This adulteration was done by adding water to make the milk go farther when being measured out, and adding formalin (for'ma-lin) to make it keep sweet. For a time many of the cereals were adulterated with sawdust, peanut shucks, or bran. Many of the special foods put up in packages used to be adulterated, and it would require a long description to enumerate all that have been found unsatisfactory for food by the Depart- ment of Agriculture. Pure Food Laivs. — Congress in 1906 passed what is known as the Pure Food and Drug Law. This law requires manufacturers of food and medicine to state on the label what is in each package or bottle. This enables one to know just what. he is buying. 150. Indigestion. — Few children that have an oppor- tunity to romp and play out-of-doors and have plenty of simple and plain food ever experience any ill feeling in the digestive canal. However, as children grow older, exercise less, and eat richer food, they may suffer much inconvenience from indigestion. Indigestion is a condition which rarely extends to all parts of the digestive canal; it is located either in the stomach or in the small intestine. This may indicate that certain kinds of food are not properly digested. Indiges- tion may be caused by eating the wrong kinds of foods or by overloading the stomach. If the food is chewed thoroughly, the appetite is usually a safe guide as to the amount needed by the body. Moreover, food thoroughly chewed is more easily acted upon by the digestive fluids. INDIGESTION 181 To some people certain foods are indigestible at all times, while other foods are indigestible only at special times. We should learn to understand our bodies in this particular. Some of the causes of indigestion are: lack of sufficient regular exercise, too much rich food, and the failure to drink enough water. Students and professional men use their brains more than their muscles, but they require protein to repair nerve waste just as laborers require proteins to feed their tired muscles. Unless students and professional men exercise their muscles, they do not feel vigorous and eager for their work. On the other hand, unless the laboring men exercise their brains, they do not do their work as well as they might. The amount of exercise required varies with the individual. The best way to prevent in- digestion is to have regular habits of eating and exercising. There are in the market many tablets and remedies for indigestion, which may, for example, contain pepsin and pancreatin. Now we know that these substances when found in the pancreatic fluid act in an alkaline medium. As these tablets must first pass into the stomach, which is an acid medium, the action of the pancreatin is probably destroyed long before the remedy reaches the intestine where it would naturally act. This means that such tablets are largely useless and is one of the reasons why many doctors believe that digestive tablets are doing more to cause indigestion than they do to help it. There are only a few commercial tablets made which act on the undigested foods of the intestine. No medicine, in fact, can give permanent relief to indigestion. Predigested foods, a recent attempt to relieve indigestion, serve a useful purpose in cases of sickness, but in our regular life, should be used sparingly because they do not give the digestive organs the proper amount of work to do. 182 LIFE PROCESSES OF MAN 151. Effect of Alcohol on Digestion. — Alcohol taken into the digestive tube is closely related to the question of in- digestion. The lining (mucous membrane) of the stomach and intestine is delicate and tender, and contains thousands of cells which secrete the gastric juice, and many more thousands that help to digest the food. When alcohol comes in contact with these delicate cells, it prevents them from doing their normal work. The result is that food is not properly digested. Indigestion disguised by alcohol *but not cured. — It is a serious error to regard alcohol as a genuine remedy for indigestion or abdominal pain. It is true the sense of pain is sometimes abolished by alcohol, and as a result of this many a man believes that alcohol aids his digestion, whereas it merely exerts a numbing effect on the stomach nerves, and his indigestion is disguised rather than removed. In fact, instead of being cured the mischief is increased since digestion is retarded. Some digestive medicines contain enough alcohol to be injurious. Alcoholic drinks taken with meals make the food hard to digest because the alcohol makes the food tough. SUMMARY Man is able to live in all climates and localities on the earth. No plant or other animal can do this. Man con- trols his surroundings. Plants and animals are controlled by their surroundings. Like other animals, man passes tli rough the periods of growth known as youth, maturity, and old age. Man has a definite set of digestive organs that are more highly developed than those of any other animal. These digestive organs prepare proteins, carbohydrates, and fats so that they pass into the blood. The blood is forced QUESTIONS 183 by the heart through definite blood vessels. The study of food is important because we require food in order t<> Live. The cost of food and the amount needed are problems that science is helping to solve. QUESTIONS How does man differ from other animals in regard to the places where he lives ? Why ? What do man and other animals require in order to grow? Name the kinds of foods. What is the value of protein? <>t carbohydrates ? What does cooking do to foods ? Why is this important '.' What is digestion ? What is indigestion? Absorption? How are the cells of the body fed ? CHAPTER XVI SKELETON AND MUSCLES 152. Skeleton and Muscles. — Muscles which serve to move the body cover and protect the skeleton of man. The more delicate organs of the body are protected further — the heart and lungs by the ribs, and the brain by the cranium. The skeleton nasal bones clavicle (collarbone! shoulder blode nu rntrus vCrani u m • V-j-Ma'ar (cheek) bone -superior maxillary bones ■ mferior and muscles of man are similar to the correspond- ing parts in the frog and the dog. Certain tech- nical differences are noted by anatomists, but in general plan or struc- ture and in their func- tions, the skeleton and muscles are alike in all the higher animals. 153. The Skeleton. — Unlike the rest of the body the skeleton proper is hard. It consists of bone and a compara- tively soft substance known as cartilage, or gristle. There are cells in the bones just as there are cells in the liver, the muscles, and in the nervous system. So, like the other parts of the 184 JV— phalanges Figure 191. — Skeleton. THE SKELETON IS") Figure 193. - - Dia- gram of Bone Structure. Figure 192. mlcrophotograph of Bone. <© «w ^> <5D //?£ CT HEJT/HG be continued for hours before natural breathing is restored. Diseases of the Respiratory Tract. — The most common of these diseases is a cold located in the nose and throat. The nasal passages be- come clogged with mucus which contains many germs. These germs are widely distrib- uted in sneezing. Diphtheria is a germ disease which is located in the throat and nose. For many years diph- theria was one of the most deadly of our dis- eases, but through the use of the diphtheria antitoxin the danger has been greatly reduced. Tuberculosis of the throat and lungs is a widely distributed dis- ease which causes many deaths each year. See page 235. 158. Blood. — The blood is the fluid which circulates through the heart, arteries, and veins, supplying nutritive material to all parts of the body. Blood is made up of a fluid (plasma) which contains cells or corpuscles ( Latin, corpuseulum, little body). The blood cells or corpuscles are of two kinds, red and white. The red corpuscles are colored with a substance called haemoglobin (he-mo-glo'bin: (iivek, haima, blood: globus, BR£ATHIN6 LIN£ ■ - OUT i- - Room //vD^yr//V£ £)/&£ c T H£A T/HG Figure 210. — Steam Heating. By Earl Hallenbeck. 198 RESPIRATION, BLOOD, AND EXCRETION Figure 211. — Micro- photograph of Blood of Frog. ball). When a few of these corpuscles are examined through a microscope, they appear yellowish instead of red ; but when a large number of them are seen in a mass, the red color is apparent. When the red cells are first formed, they have a nucleus which gradually disappears. As a result, the mature red corpus- cles, unlike all the other cells we have studied thus far, have no nucleus. Red corpuscles are about 3<>Vo °^ an incn iR diameter and T2T0 o °^ an ^ncn thick. The red corpuscles carry oxygen from the lungs to the cells of the body. This oxygen unites with the haemoglobin. By osmosis the oxygen passes from the blood to the body cells which are deficient in oxygen. These cells take the oxygen and use it in the process of oxidation, which goes on continuously in every living cell. A good supply of red blood corpuscles is, therefore, necessary, if the cells of the body are to have a Figure 212. sufficient supply of OXy- As the blood flows through the capil- 2"en. The feeding" of ^aries which are found in all voluntary . ,, . , . muscles, for example, oxygen and other the cells with oxygen is food products are given off to the muscle One part of respiration. cells, and carbon dioxide and other At the same time that waste substances Pass off from these same muscle cells into the capillaries oxygen is received from on the way int0 the veins. the blood by the body cells, carbon dioxide is given off. Again osmosis explains the method of this transfer. Most of the carbon dioxide is BLOOD 199 Figure 213. — Organs of Circulation. Veins, black ; arteries, with transverse lines. Left side of figure shows superficial vessels, while right side shows deeper vessels. 200 RESPIRATION, BLOOD, AND EXCRETION carried by the plasma, although some of it unites with the haemoglobin. White blood corpuscles are much like the amoeba in that they are colorless and can change their form. They move about in the body and often leave the blood vessels and collect at one place to aid the body in destroying disease germs. The blood plasma is straw-colored and varies in compo- sition from day to day, and hour to hour. It contains the foods on their way to the cells and waste products on their way to the kidneys, lungs, or skin. The volume of blood in the average person is about six quarts. When exposed to the air, blood forms a clot, because of the presence of a substance (fibrinogen) which produces fibers that hold the red and white corpuscles. Student Report on Blood Name of Animals © N X o p-1 o O H O a w « o Hi o Color in Plasma CO C P o 5 o o o *3 ►4 W m H >— < w o 03 159. Heart and Blood Vessels. — The blood is carried from the heart to all the cells of the bodv and back to the heart again and again. The heart serves as a pump to force the blood along. The heart is about the size of the fist and has strong muscular walls. In a healthy person, it contracts regularly about seventy times a min- HEART AND BLOOD VESSELS 201 J*> ute. It is obvious, therefore, that the work which the heart does is very great.1 The heart is located in the thoracic, or chest cavity, a little to the left side and between the lungs. It is a cone-shaped organ, inclosed in a membranous bag" called pericardium (per-i-car'di- um : Greek, peri U around ; cardia, heart). The heart is divided by a wall into right and left chambers. A nearly complete cross parti- tion divides each side into upper chambers, the auricles, and the lower ones, the ventri- cles. The opening between an auricle and a ventricle is guarded by a valve, which is partly membranous and partly muscular. The auricles receive blood from the veins, while the ventricles force blood into the arteries. Artery is the name given to the blood vessels which carry blood from the heart, and vein is the term applied Figure 214. — Heart. Figure 215 Diagram Vein. of Showing the valves. 1 " The work the heart does during the day is about equal to the energy expended by man in climbing to the top of a mountain 3600 feet high. Assuming that the man weighs about 150 pounds, this would be equal to an amount of energy sufficient to lift 00 tons to a height of three feet The work of the left side is greater than that of the right, since the former has to drive the blood all over the body, while the latter baa only to force it to the lungs which are near by. For this reason the muscle walls of the right ventricle are much thinner than those of the left ventricle." — Conn and Buddington. 202 RESPIRATION, BLOOD, AND EXCRETION Figure 216. — Diagram of Capillaries. The artery breaks up into minute branches, the capillaries, which in turn unite to form veins. to the vessels which return blood to the heart. There is little structural difference between the veins and arteries except that the walls of the arteries are thicker, and there are no small valves as in the veins. As the branches of the arteries become minute, the walls become much thinner, thus allowing the food and oxygen to pass more easily to the individual cells. These minute branches are called capillaries (Latin, capillus, hair). From a cluster of capillaries a small vein begins which soon connects with a slightly larger vein, which leads back to the heart through larger and larger veins. The blood follows a regular course through the body, pass- ing from the left ventricle into the aorta, which is the largest artery in the body. As soon as the aorta leaves the heart, smaller arteries branch from it, and the aorta itself also branches until the entire body is sup- plied with blood. The right ventricle gives off a short arterv which divides, and a branch enters each lung. At the point where an artery leaves a ventricle, there are three half -moon-shaped valves which prevent the blood from flowing back into the heart (Figure 215). To Brain To Skin --To Arm "-To Lung To Kidneys^ To Stomach •To Small Intestine :_ ";:To Back To Large Intestine -To Leg Figure 217. — Main Arteries of Frog. HEART AND BLOOD VESSELS 21 >3 I 0 I All to Back 4^;;^ To stomach - — \ To Kid- ' p^-^Jo Reproductive organs To L.i ■ The blood which is carried into the lungs contains a large amount of carbon dioxide which gives it a dark color. In the lungs the carbon dioxide is given off and oxygen taken up, so that when this blood is returned to the left auricle, it is of a bright red or " arterial " color. Every time the heart beats the blood is forced into the arteries in waves which can be felt in the wrist or neck by placing the finger over an artery. The wave is called the pulse. By counting the number of waves each minute, the rate at which the heart beats is determined. When a person runs or takes violent exercise, the pulse rate increases. It is advisable to know what our usual pulse rate is, for an increased pulse rate is sometimes an indication of approaching illness. Lymph. — As the blood flows through the capillaries, part of the plasma passes through the thin walls into the spaces between the cells and bathes the cells. This fluid which escapes from the capillaries is called lymph (llmf). It is composed of digested food, water, and other sub- stances. The cells take up the food which they nerd and cast back into the lymph the wastes which they have formed in the process of growth and repair. These spaces between the cells are small and irregular in shape. The To Legs Figure 218. — Main Arteries of Man. Compare with Figure 217. 204 RESPIRATION, BLOOD, AND EXCRETION spaces, however, form a sort of mesh, or net, the parts of which join, forming larger vessels, and finally all the lymph is collected into two large vessels which open into veins. Thus there is the lymphatic circulation which differs from that of the blood in several ways. (1) There is no special organ for forcing the lymph along, the circula- tion depending mainly upon the movement of the muscles. Figure 219. — Superficial Lymphatics of Arm and Hand. (2) The lymphatic vessels are imperfect in the beginning, being only irregular spaces. (3) The lymph contains no red corpuscles and only a few white corpuscles. Cuts. — Since every part of the body inside the skin is traversed by blood vessels, we cannot injure any part without breaking at least some of the blood vessels. A small cut causes the blood to flow only from capillaries, and it flows slowly and in small quantities. If a vein is cut, the blood will be dark in color, and will flow in larger quantities, but steadily. A severed artery sends out bright red blood in waves corresponding to the beat of the heart. To stop the flow of blood from a vein, com- press the vein beyond the cut ; from an artery compress the artery between the cut and the heart. In either case remain quiet to aid the blood to form a clot. Exercise. — The object of a circulatory system and of a circulatory fluid is to supply every cell in the body with HEART AND BLOOD VESSELS 205 food and to carry away the waste. The more active tin- process of circulation, the more perfectly is this object accomplished. It is the common experience that the heart beats more rapidly, the lungs work harder, and the body becomes warm after a few minutes of vigorous exercise. These changes have a decidedly beneficial effect upon building up the body and removing tin- wastes. In most kinds of work only one set of muscles is used. This set gets a full supply of blood, but others get less than a full supply and so they get too little food and ac- cumulate too much waste. Every one should, at some time in the day, take exercise in the open air which will bring all his muscles into play. If it is enjoyable exercise, tin- effects upon the mind react favorably uj)on the body. This is the advantage of such exercises as skating or baseball. In the winter it often requires real effort to force oneself to leave a warm room and to go out for ex- ercise, but if one is properly clothed, cold air has a bracing effect not obtained at any other time of year. Fainting. — Fainting is due to an insufficient supply of blood in the brain. This lack of blood may arise from several causes, but the most common is some disturbance of the digestive processes, which causes the heart to beat too slowly. A fainting person should be placed flat on his back, if possible, with his head slightly lower than the rest of his body, and should be given plenty of fresh air. A dash of cold water in the face, or a bottle of ammonia held to the nostrils, is often helpful in restoring conscious- ness. TJie Effect of Drugs and Alcohol. — "The flow <>f tin- blood is modified by various drugs, some causing the blood to flow more rapidly, others more slowly. Coffee cans. - the heart to beat harder and at the same time causes some 206 RESPIRATION, BLOOD, AND EXCRETION of the arteries to become smaller. For this reason it is called a stimulant." —Conn and Buddington. It has been stated frequently that alcohol increases the activity of the heart. Careful experiment, however, shows that not only is the effect not that of a stimulant, hut that when used in large amounts, it markedly weakens the action of the heart. If taken only in small amounts, the heart sometimes shows a slight increase in its rate of beating, but this occurs only when the brain becomes ex- cited, and if the person is kept quiet no change in the heart beat is noticeable. Thus the primary action is on the brain. " A second effect of alcohol is more evident. The small blood vessels in the skin are enlarged. This produces a flushed skin, a feeling of warmth, and a false feeling of increased circulation. Its result is to send more blood through the skin with consequent extra loss of heat. This action is evidently not due to stimulation, but to the re- laxation of the muscles, and is thus a decrease of activity rather than an increase, even though the blood does flow a little more rapidly through the skin. These facts make it clear that alcohol cannot be properly called a stimulant of the circulatory system." — Conn and Buddington. 160. Excretion. — Every animal uses energy in carrying on its work. During this process a certain amount of waste substance is produced, which has to be removed from the body. The skin, kidneys, and lungs are the chief organs which assist the body in getting rid of this waste. When any part of the living cells is broken down in the simple act of living, a waste product results. By osmosis these waste products enter the blood and are removed by the lungs, which give off carbon dioxide; by the sweat glands in the skin; and by the kidneys, which remove the wastes that contain nitrogen. The sweat EXCRETION 207 glands and kidneys are usually regarded as the excretory organs of man. These organs remove from the blood the wastes which have been excreted by the cells of the body. The excretion from the living cells is one of tin* funda- mental life processes of all plants and animals. This form of excretion should not be confused with the in- digestible part of the food which is not taken up by the blood and which passes out through the large intestine as fseces. The kidneys are two bean-shaped organs lo- cated in the abdominal cavity, one on each side of the "small" of the back. Each is about four inches long, two and a half inches wide, and half an inch thick. The color is a dark red. The kidney is made up of two' layers, the outside or cortical, and the inside or medullar jf. Each layer is com- posed of many small tubes (tubules') which open into an area called the pelvis} the space within the kidney. The pelvis continues into a duct (ureter), and from each kidney the ureter passes into the bladder. A small duct (urethra) connects the bladder with the exterior of the body. Each tubule in the kidney is in dose relation with the Figure 220. — Section of Kidney. i The word pelvis is also used in referring t«> the hip bones, and it Is better to call the latter structure the bony pelvis. 208 RESPIRATION, BLOOD, AND EXCRETION Arterrj uriniferous tubule Figure 221. — Diagram. Showing relation of artery and vein to portion of minute kidney tube (uriniferous tubule). blood capillaries. At the place where this close re- lation takes place, glomeru- lus (glo-meVu-lus), the walls of the capillary and the walls of the kidney are very thin. Through these thin walls a large amount of water filters out of the blood into the tubes. At the same time waste ma- terial which contains nitro- gen, salts, and other organic wastes is removed. If these wastes are not removed, they create toxins which poison the body. SUMMARY All living things breathe oxygen which, in the higher animals, is carried by the blood to the cells of the body. The parts which man uses in breathing are more highly de- veloped than in any other animal. Man has a voice box, the larynx, by means of which he is able to make a wide variety of sounds. The blood of man is similar to the blood of all the other vertebrates, although not identical. It consists of red and white corpuscles which move freely in the plasma. The blood is confined in the blood vessels through which it is forced by the heart. Excretion includes the waste products derived from living protoplasm. The kidneys and sweat glands remove the liquid wastes from the blood. QUESTIONS Compare the respiration of man, the hydra, and the earthworm. Com- pare the lungs of man with the gills of a fish. What is blood ? What is its use ? What is the difference between veins and arteries ? Explain the work of the kidneys and of the lungs CHAPTER XVIII THE NERVOUS SYSTEM OF MAN 161. Parts of the Nervous System. — The nervous system of man consists of the same general parts as the nervous system of the frog (See page 118). There is a brain and spinal cord, from which nerves extend to the special senses, the muscles, the heart, and the stomach. When the brain of man is compared with that of the frog, it is obvious that the cerebrum of man is proportionately larger. Although some of the other parts of the brain appeal unlike the corresponding regions in the frog, scientists tell us that they are really the same. 162. The Nerve Cell. — The nervous system of man con- sists of many thousands of nerve cells which differ from all other cells in having more parts and branches (Figures 223, 224, 225). The nerve cells are unlike other evils in appearance, although they have the usual parts. Ex- amination shows that the nerve cells have a prominent nucleus surrounded by cytoplasm, which grows out into a number of branches called fibers. The shorter branches divide and form, together with the branches from the neighboring nerve cells, a mass of tangled fibers. There is usually one unbranched fiber, perhaps several feet Long, which ends either in the skin, in some muscle, or in tin- nervous system. When this long liber readies the muscle or skin, it divides into several fine branches. All of these branches which arise from a nerve cell belong to it, and in this connection the word cell includes all the branches, the nucleus, and the cytoplasm. 209 210 THE NERVOUS SYSTEM OF MAN 163. The Location of the Nerves. — The nerve fibers which have the same work to do occupy certain definite places in the brain or spinal cord. So a student of the nerves can tell the route which the stimulus arising from feeling a pencil must travel before reaching that part of the brain where it is interpreted as a pencil ; or the route over which the stimu- lus arising from tast- ing candy must pass before it is known to be candy. When we see the pencil or the candy, the route over which the sight stimuli of these two objects travel is not the same as that of the feeling of the pencil or tasting the candy. The nerve cells which interpret the stimulus arising from feeling the pencil or from tasting the candy or seeing the pencil and the candy are probably not the same. We may say, therefore, that the spinal cord and brain are made up of many Figure 222. — Nervous System of Man. GROWTH OF THE NERVOUS SYSTEM 211 Figure 223. — Nerve Cells. special nerve pathways which end in nerve cells thai interpret stimuli. The nerves which connect the central nervous system, that is, brain and spinal cord, witli all parts of the body, consist of many long nerve libers. Each nerve looks like a small white thread and is covered with a thick, fatty sheath (medullary sheath). In the living animal, this fatty sheath is white and the nerve fibers so covered are found to occupy a certain part of the spinal cord and brain. Thus, we get the name white substance. Other of the nerve fibers and cell bodies are not covered with a sheath and so have a gray appearance. Thus we have the term gray substance in connection witli the nervous system. 164. Growth of the Nervous System. — The nervous system of man, like all other parts of the body, lias a definite beginning and grows in an ordered manner. Not only is this true in man, but also in the frog and fish. The tissue of the embryo, which is to grow into brain and spinal cord, gradually changes until the adult parts are formed. During this early period of growth, the nerve cells send out processes which become nerve fibers, so that at birth the Figure 224. -Nerve nervous system is ready to go to work. Cells. Indeed, nearly all the nerve cells which 212 THE NERVOUS SYSTEM OF MAN 4 .. ft* °0 6* » O Oo >© © * »° ? . * ~ • • %%° •V.-*.*:" motor ce II muscle Figure 226. — Diagram to show Reflex Action. The stimulus comes in contact with the skin and is carried to the spinal cord. It then passes to the motor cells which carry the order to the muscle. The same skin stimulus goes to several other parts of the spinal cord. REFLEX ACTION 213 withdrawn the following actions take place. The heal stimulus affects the nerve endings in the finger and that stimulus is carried to the spinal cord. If this were all that occurred, the finger would burn, because this stimulus and the nerve fibers over which it travels have no control over the muscles. The removal of the linger calls into play an- other set of nerve cells, — the cells which have their fibers ending in the hand and arm. All of these changes take place involuntarily, and the reaction to the stimulus is known as reflex action. Specific names are used in de- scribing these several changes ; the nerve fibers which connect the skin with the spinal cord and brain are called afferent (affer-ent: Latin, ad, to ; fero, to carry ) fibers because the stimulus always travels toward the brain. Their function is sensory, for they carry the stimulus to the brain. The fibers which connect the muscle with the brain or spinal cord are the efferent (ef'fer-ent : Latin, ex, from ; fero, to carry) fibers, because they carry their message away from the central nervous system. Their function is motory. In the special instance we are study- ing, the heat stimulus causes the spinal cord to send a special message to the muscles of the finger, so that the latter is removed from the stove. This is a typical illustration of the simplest way in which the nervous system works, but in most reflex actions there are other results. After the finger has been removed from the hot stove by reflex action, we soon realize that the skin is burned, the realization oniim; through the smarting sensation. This second stimulus has been carried to the brain, and we are now conscious of the stove, heat, burn, etc. If there were no afferent nerve fibers, the individual could not experience any pain when hurt. 214 THE NERVOUS SYSTEM OF MAN The afferent and efferent nerves, whether in reflex or in general nervous action, never vary in the work which they do. The sensory afferent nerves form the only paths over which our knowledge of the outside world travels to the brain. The stimuli which cause the different sensa- tions, such as taste, sight, etc., have their individual paths and receiving organs. This is indicated by the fact that no other nerves than those of the ear are ever affected when we hear. Reflex Action in the Frog. — The frog, like man, is able to act in a definite way. If any one approaches a frog while it is sitting on the edge of a pond, it jumps into the water, stirs up the mud, and then returns to the shal- low water near the place where it entered. The frog, in this case, acts as if it, or its ancestors, had learned that this is the best way to escape enemies. While this series of acts is called a habit, it is really a series of reflex acts which are similar to the reflex action described for man, and require the same nerve structures. Reflex Action in the Earthworm. — If a light is flashed on an earthworm at night, the worm will quickly with- draw to its burrow, before it can be seized. The earth- worm has no eyes, but it is able to respond to light and can tell the difference between night and day. It is believed that special nerve cells in the skin, which are connected with the nerve ganglia, help the earthworm to become aware of the light stimulus. Reflex Action in Hydra. — Hydra is a minute water animal which has no definite nervous system, but only a few nerve cells scattered through the body. As the hydra waves its arms about in the water, there seems to be no purpose in its motions. But if a water flea swims against one of the tentacles, a part or all of the tentacles at once begin to carry the flea to the mouth of the hydra. SENSE ORGANS 215 The hydra, then, without a definite nervous system, ran carry out a definite reflex action. Reflex action is similar in all animals. In all of these illustrations, it is necessary for the stimulus to be received by an afferent nerve, or some structure which can do the same work, and for the stimulus to be transformed into a series of purpose-like movements. 166. Sense Organs. — All of the higher animals have eyes, ears, a nose, and a tongue. Each of these organs contains nerves specialized to respond to a certain definite kind of stimulus. The result of this specialization is that not only are these special sense organs complex: in struc- ture, but also the region of the brain which receives their messages. The ear nerve responds to a stimulus of air-waves of a certain length, and we say we hear a sound. The eye nerve is stimulated only by light. Each nerve and the brain cells to which it sends its messages have become so specialized that practically only one kind of reaction takes place. For example, all stimuli acting upon the eye nerves are interpreted as light. The skin is a simpler sense organ than the eye or ear. and tells us of pain and touch and the difference between heat and cold. The Eyes. — The eyes of all vertebrates have the parts arranged in a similar manner. The eyeball is roundish and is located in the eye sockets of the skull, which are termed orbits. There is an upper and a lower eyelid, and the remains of a third eyelid in the corner next to the nose. The front of the eve is covered by a transparent membrane, the cornea (kor'ne-a); and the rest of the eye is surrounded by a tough membrane, the Bclerotic coat, or the white of the eye. Within the combined covering of the cornea and sclera are a number of struc- 216 THE NERVOUS SYSTEM OF MAN tures which take part in receiving and transmitting the rays of light to the brain. A cross section of the eye shows two more membranes in close relation to the sclerotic coat (Figure 227). The membrane in direct con- tact on the inside with the sclerotic layer is the choroid (ko'roid). The choroid coat is filled with blood vessels and pigment. Through this layer the food in the blood is distributed to the eye. The third layer or coat is the retina, which is com- posed of nerve cells and which is nearly trans- parent. The cornea and these three layers inclose two chambers which are separated by the lens (Figure 227). In front of the lens a curtain-like membrane, the iris, partly covers the lens, except for a round opening in the center which is called the pupil. The color of the eye, gray, black, blue, or brown, is due to the presence of pigment in the iris. The small front chamber is filled with a transparent fluid which is composed principally of water and is known as the aqueous (a/kwe-us) humor. The large back chamber is filled with a thin, transparent, jellylike fluid, the vitreous (vit're-us) humor. In order that wTe may see any object, a pencil in our hand, for example, two general conditions must be present. The picture (image) of the pencil must be placed on the retina, and this picture must be carried to the brain by Figure 227. — Section of Eye. C, cornea ; C', choroid layer ; /, iris ; I. C, inner chamber ; 0. C, outer cham- ber ; L, lens ; 0. N, optic nerve ; R, retina ; S, sclerotic coat. e Figure 228. — How we see the Pencil. SENSE ORGANS 217 the eye (optic) nerve. When these two conditions bake place, we see. As we have learned, the stimulus for the eye is always light. In physics we learn that the rays of light brave] in straight lines. This fact explains why we cannot round a corner. When the rays of light are made to pass through a glass lens, the rays which pass through the thin edges of the lens are bent and do not travel to the same place they would have reached had they not passed through the lens. In the same way light rays from an object pass through the lens in our eyes and are bent. This results in the image of the object, the pencil in this instance, being in- verted on the retina. The light rays of the pencil stimulate the nerve cells in the retina, and this stimulus, after being carried to the brain, is interpreted to us as a pencil, though we do not know how stimuli travel on nerves. The inverted image of the picture on the retina is made to look natural to us because we are used to seeing everything in inverted imag Care of the Eyes. — The eyes are our most precious sense organs, and as such they should receive the best of care. Certain imperfections in the lens or other parts of the eye can be helped by the use of glasses. If your «\ ea annoy you, or if you cannot see objects as clearly as your schoolmates, have a competent oculist examine and treat them. The Ear. — The ear is a sense organ for the reception of the stimuli which we interpret as sounds. The ear of man consists of the outer, middle, and inner ear. The first two carry the stimuli to the third, where the}' are received by nerve cells and carried to the brain. 218 THE NERVOUS SYSTEM OF MAN The diagram of the ear (Figure 229) shows the several parts and their relations. The outer ear leads to the tym- panic (tim-pan'ik) cavity ; the middle ear is in commu- nication with the mouth, and the complex inner ear is partly shown. There is a group of small bones in the middle ear which conduct the sound vibrations to the delicate inner ear. The internal ear receives the various sound waves, and transmits them to the brain, where they are explained as sounds.1 Hearing. — Sound waves strike the ear drum (tympanic mem- brane), which in turn causes the small bones in the middle ear to vibrate. The bones cause the water in the internal ear to move, thus stimulating the nerves of hearing. The pressure of air on each side of the ear drum is nor- mally the same. This is due to the entrance into the mid- dle ear of air from the mouth, through the eustachian tube (see page 166). This tube is a trifle more than an inch long. When it becomes closed, partial deafness results. Defects in hearing may be caused by blows upon the ears, by the accumulation of wax in the ears, and by sore throat. When there is a continued ringing or hissing sound in the ears, consult a doctor at once. 167. Brain Efficiency. — While the efficiency of the brain depends upon mental training, in order properly to exer- cise the many functions of this organ at least three things Figure 229. — Plan of Ear. 0. E, outer ear ; M. E, middle ear ; /. E, inner ear ; Eu, eu- stachian tube. 1 When certain parts of the ear (semicircular canals) are injured, one has difficulty in standing or in walking erect. This is because the inner ear serves both as a hearing and a balancing organ. BRAIN EFFICIENCY 219 SKILL AND ENDURANCE IMPAIRED BY DRINK Tests in Target-Shooting in Swedish Army I. SKILLED TESTS Thirty shots fired in quick succession Non-Drinking Days: Average 24 hits oat of80 Bhots Drinking Days: Average 8 bits onl of :5n Shots ■ Alcohol taken equal to amount in P.j to 2 pints of 5 per cent beer, •_'(» to 80 minutes before shooting, and an equal amount the night before II. ENDURANCE TESTS Non-Drinking Days: 860 Bhots fired be- fore exhaustion Drinking Days: 2TS shot- fired before i I haustion Alcohol taken 3o minutes before tesl vras amount contained in about ll/4 pints of 4 per cent beer are necessary: good food, sufficient sleep, and abstinence from alcohol and tobacco. We have already discussed the question of food (page 169). The amount of sleep which grown people need depends in part upon the kind and amount of work they do. But all young people require a large amount of sleep. Chil- dren from seven to ten years of age need at least twelve hours of sleep every night, while youths of high school age need at least nine hours, and ten would be better. At a baseball game, you have noticed a boy catch a " fly " when it looked like a " home run," or how enthu- siastic the crowd became when the pitcher struck out the last man with the bases full. The nervous system of both players was efficient in a critical test. We all ride on the street cars or railroads, but do you know that most of the men who run the street cars and trains have to pass an ex- amination to determine whether they can be trusted to do their work properly and well ; i.e., whether their nervous systems will stand the test? Among the questions which their prospective employers are sure to ask is. M Do you use alcoholic drinks ? " In order to judge the success of a piece of work we must consider the quality and speed with which it is done. Kraepelin made the following experiment, the results of Figure 230. 220 THE NERVOUS SYSTEM OF MAN which show that both these elements in mental work are influenced by the use of alcohol. Several men who were allowed to drink no alcohol util- ized half an hour daily for six days in adding figures. Their ability to add increased each day. On the seventh day the work was begun under the influence of alcohol. In spite of the skill gained in the previous practice, their accuracy did not increase, but on the contrary began to de- crease rapidly. On the nineteenth day the use of alcohol was stopped, and immediately an improvement in the work manifested itself ; but on the twenty-sixth day, when the use of alcohol was resumed, a decided decrease in the power of adding manifested itself.1 It is difficult to estimate how efficient each of us may become in our life work, but one thing is certain, that if we use alcohol, we shall lose that perfect control over our nervous systems, which enabled the two players to be so efficient in the ball game. It is also equally certain that if we use alcohol, we shall find fewer men willing to em- ploy ns in places of responsibility, not only because of our 1 Schiller was wont to say, " Wine never invents anything," and Helmholtz, one of the greatest observers and thinkers of the nineteenth century, noted in himself the effect of alcohol in interfering with the highest powers of thought and conception. At the celebration of his seventieth birthday in Berlin, when the courts of Europe and the whole scientific world joined to confer numerous honors upon Helmholtz, he described in the course of a speech the coudition under which his highest scientific thoughts had matured and come to fruition. He said : " Frequently they slyly enter the mind without one's immediately attach- ing any importance to them ; later some very simple accident or circumstance may be sufficient to reveal to us, when and under what circumstances they arose, or they may be present without our even knowing from whence they came. At other times they come to us suddenly, without any exertion what- ever, just as an inspiration. As far as my experience is concerned, they never came to a wearied brain, or at the writing desk. They were especially inclined to appear to me while indulging in a quiet walk in the sunshine or over the forest-clad mountains, but the smallest quantity of alcohol seemed to scare them away." ALCOHOL, A NARCOTIC 22 1 DRINK impaired SCHOLARSHIP A Comparison of Abstaining and Drinking School Children in Vienna Investigation concerned ">sv» pnpili in ll classes Drinks used included Wine. Beer and Knm in tea mental inefficiency, bnt also because of our unreliable judgment. Alcohol Shortens Life. — At least nineteen of the great American life insurance companies do not consider thai ;i man who uses alcohol is a good risk, because be does not live so long as the man who abstains. The statistics of one insurance company, which cover the period 1*H4- 1909, show that during that period 79.7 % of their risks who were moderate drinkers died ; while but 52.2 °f0 of the abstainers died. In the case of a second company, during the period 1886-1909, 93% of the drinkers and only 70 % of the abstainers died. 168. Alcohol, a Narcotic. — Before studying this subject further, we must understand the meaning" of the terms poison, anesthetic (an-es- thet'ik), and narcotic. A poison is a substance which when taken into the body tends to cause death. Aco- nite, opium, carbolic acid, and mercury are all poisons, and when taken in sufficient quantities cause death. An anesthetic is a substance like ether or chloroform, which when breathed into the lungs causes a temporary loss of sensation. However, unless anesthetics are admin- istered properly, they may cause death. A narcotic is a substance which causes dullness or stupor, and even a temporal}' relief from pain. = Highest W. Fair nans Poorest 134 Abstaining Children 42% 49 y//Mw/W/Z$Z>/.. J 164 Who Drank Occasionally 34% 57' ; ■ 219 Who Drank Once a Day 29' 71 Who Drank Twice a l):i\ 25% 58 18', Highest Scholarship Decreased, Peered In- creased, as the I se of Lleohol »;is Increased [nveatigation bj E. Bajrr, School Din Figure 231 222 THE NERVOUS SYSTEM OF MAN Assaults and Drink 1,115 Assaults in Heidelberg, Ger., 1900-1904 66.5'; Committed in Saloons 8.8% 7.8% 7.7% 9.2% Committed in Street Committed in Workshop Committed at Home To understand how alcohol comes to be classed as a narcotic, it is necessary to learn about a substance called lipoid (Greek, lipos, fat ; eikos, like). " Within recent years a new sort of body substance has been discovered, and has been elevated to first-rate im- portance. This new class is termed 'lipoid.' Its impor- tance is immense. It is quite as important in the body as the nitrogenous or albuminous material which is present in every living tissue. It is very like fat in many re- spects, but in other respects it is different. It contains nitrogen, which fats do not; it contains phosphorus, which fats do not; again it mixes with water, which, as is well known, fats do not. It has certain remarkable properties, in that it can make certain bodies soluble which are otherwise not soluble. " The walls of practically every living cell in the whole body are made chiefly of lipoid, and it is found that there are strands of this material running through and through the sub- stance of every cell. In fact, there is no region of any cell in any part of the body that is without this material. " Perhaps the largest accumulation of lipoid is that in the nervous system. There is far more lipoid in the brain than in any other tissue. If you examine a nerve, or what physiologists call a nerve trunk, you will find Place Unknown Man; assaults committed outside the saloon were also due to drink The Sober Man Thinks Before He Acts Alcohol Makes a Man Act Before He Thinks It causes irritability ; weakens the judgment and self-control needed to hold irritability in check " Our statistics (from the United States) point to the conclusion that intemperance is the one moxt prolific source of the criminal co)u/itio}i.'n — Co.m.m. of Fifty. Figure 232. ALCOHOL, A NARCOTIC 223 that this nerve is composed of many thousands of nerve fibers, and each nerve fiber that conveys messages into or out of the brain is invested with an insulation jacket (sim- ilar to the insulation covering an electric wire) of Lipoid and thus the stimuli are prevented from scattering. "It may be asked, 'What has all this to do with alcohol?' The connection is an important one, for only a few years ago two physiological investigators, — one with the English name of Overton, and the other with the dis- tinctly German name of Hans Meyer, — without knowledge of each other's work, discovered the principle that any substance that dissolved lipoid, or, what is the same thin.;, is dissolved in lipoid, is an anesthetic. Chloroform, ether, and all of these agents which are used in modern surgery to produce unconsciousness are dissolvers of lipoid. "Besides acting as anesthetics such substances act as poisons to every living thing in the body as well. The brain, owing to its high tt'iciency Onter Wora Centers Balancing Centers BreathingCeM.r Hrtii Ccnler percentage of lipoid, is more sensitive to the action of chloroform than other organs of the body. " When chemists and physiologists found that alcohol is soluble in lipoid, it enabled them to rank it as a narcotic poison, and it is now so classed. This statement is altogether irrespective of the effects it will produce on an animal." — Osborne. The question of brain efficiency is further illustrated by Figure 233. Long before birth the heart in the embryo begins to beat and is under the control of the nervous Nerve to Heart Figure 233. — Brain Control. 224 THE NERVOUS SYSTEM OF MAN Abstainers' Advantace In a Championship Walking Match MATCH HELD AT KIEL, GERMANY, 1908 59 Non-Abstainers, 24 Abstainers Entered Contestants Entering Match Kon- Abstainers 71% Abstainers 29% Percentage of Prizes Won By \nn- Abstainers 40% By Abstainers 60% Of First 25 to Reach Coal system. The part of the brain which superintends the heart is located in the medulla, where a special cluster of cells sends out nerve fibers which enter the heart nerve. These nerve cells are called the heart center. The next nerve center to begin work is the breathing center, located close to the heart center, which controls the breathing. This does not become active until after birth. About a year after birth, several more nerve centers be- come active in the child's brain. These are the ones which help him to walk. The cere- bellum contains nerve cen- ters which play an important part in walking and in learn- ing to balance. The muscles which move the arms and legs are regulated by nerve centers in the cerebrum. Soon after the child learns to walk, he begins to talk and learn words. The sev- eral nerve centers which now become active are all located in the cerebrum. These are the nerve cells which are necessary in speaking, hear- ing, reading, and writing words. After fifteen years of age the brain goes through important structural changes and the young person begins to do difficult tasks well. It is difficult to locate the exact spots in the cerebrum where the nerve centers are that now become active, for they are widely distributed. These nerve centers may be called the efficiency centers and they are the last to develop. But Failed to Reach Coal 94% were Non- Abstainers 6% were Abstainers Abstainers won 1st, 2d, 3d, 4th, 8th Places. Xon-Abstainers, 5th, 0th, Tth Places. Figure 234. STRUCTURAL CHANGES DUE TO ALCOHOL 22.") as they become active, every one becomes skillful along some particular line, although many years of training are necessary before the maximum of efficiency is reached. The efficiency centers which are the last to become ac- tive and which require so much energy to train properly are the first to be affected by alcohol. 169- Structural Changes Due to Alcohol. — Definite changes are found in the protoplasm of nerve cells after the use of alcohol. These consist in a shrinking of the nucleus, the loss of the spindle-shaped (Nissl) bodies (Figure 224), the swelling of the cell, and the presence of vacuoles in the cytoplasm. It is also probable that some of the nerve cells are actually destroyed. These physical changes explain why the results are so great and why complete recovery of mental efficiency in the drunkard is so doubtful. The modern point of view and the one which is becoming firmly established in the treatment of drunkards by physicians is that alcoholism is a disease. Many of the authorities on alcoholism are urging that drunkards should be cared for just as we care for people sick with diphtheria or tuberculosis. Anything which can destroy all of the higher and finer emotions, take away ambition, destroy shame, modesty, pride in personal appearance, render one especially liable to common diseases, or lead unerringly to insanity is to be avoided by those who are strong enough to resist, and should be made inaccessible to those who are weak and ignorant. And alcohol has all these effects on man.1 1 Alcohol tills our state hospitals for the insane. Insanity is a disorder <>f the mind due to various causes. The one cause which produces thegreatesl number of cases is the intemperate use of narcotics, «>f which ah-,, In, I in it- various forms is the most common. No less than twenty-sis per cenl .>!' the inmates of our state institutions for the insane have become deranged :i- the result of intemperance. There can he no doubt that some persons air more Busceptible t" the in- fluence of alcohol than others. They become easily intoxicated and readily 226 THE NERVOUS SYSTEM OF MAN 170. Tobacco. — " Training starts to-morrow, no more smoking," is part of the athletic coach's orders at the succumb to disease. Others appear to resist the daily use of moderate quan- tities for a long time and, to the ordinary observer, seem to be in good health. Slow changes, not easily detected, however, are taking place in the blood vessels, brain, stomach, and other organs, which will in time become apparent in serious ill health. Tbese changes are organic, that is, the structure of the organs is changed, and even if the alcoholic drinks be then wholly aban- doned, the organs will not return to a healthy condition — though further damage may be averted by this course. " Influence of Alcohol on the Development of the Brain. The brain and spinal cord do not reach complete development until the age of twenty-four or twenty-five yeai'S. During that time it is of particular importance that they be well nourished, supplied with an abundance of pure oxygen by the blood, and that all substances likely to injure their delicate structure be excluded. One would not expect to produce a fine flower from a plant which had been neglected or abused. It is well known to the florists who raise wonderfully beautiful chrysanthemums that perfect blooms cannot be produced on plants which have suffered even a slight injury from drought or other cause. No amount of care subsequently bestowed will result in anything more than a mediocre blossom. The human brain is in structure and function the most wonderful product of nature. It needs even more than a plant to be protected from harmful influences, in order that its millions of tiny cells and fibers may be properly built up day by day as the brain and body grow. Alcohol will produce in a mature man such a disturbance of the functions of the brain and spinal cord that he will be for a time unable to walk steadily or to speak distinctly. It would be idle to expect the immature nervous system of a boy or girl to develop properly if exposed, even occasionally, to the influence of such a powerful poison. The bad effect is twofold. Healthy growth is inter- fered with, and the habit of craving a stimulant is more easily acquired than in an adult. The same is true of the tobacco habit ; it is seldom contracted except in early life. It has been found among those who became insane from the use of alcohol, that a very large majority began its use when less than twenty years of age. " Persons most easily harmed by alcohol are those who are most suscepti- ble to it. One who becomes intoxicated by a relatively small quantity of alcohol, who when under its influence shows a change of disposition by speech or behavior different from what is normal to him, or who after its effects have passed away cannot remember what he did or said while under its influence, has this susceptibility. Its continued use by such a person will inevitably lead to the most serious results. The same is true of all women. Women and girls are more susceptible to alcohol than the opposite sex, and show, at an early period, that peculiar blunting of the intellectual and moral faculties which make their appearance at a later period in men." — R. H. Hutchings, M.D., Superintendent, St. Lawrence New York State Hospital for the Insane. HOW THE SMOKER'S HEART IS AFFECTED 227 beginning of eacli season. lie knows that the boy who smokes cannot reach his highest efficiency <>r be relied upon at critical times in the contest. He would rather have boys who do not smoke, because they an- stronger, larger, and steadier than those who smoke. The cigarette habit has spread until it threatens the health of thousands of boys of America to-day. How is it known that their health is not so good ? The charts on "smoker's heart' prove this point. 171. How the Smoker's Heart is Affected. — The follow- ing illustrations on the rate of the heart beat and the strength of the pulse, by W. A. McKeever, show what really happens when we smoke. There is much in these illustrations to warrant the conclusion that the heart of the habitual cigarette smoker is weak and feeble, except for the few minutes during which he is indulging the habit, and that the pulsations at this time are unduly excited. Figure 235 shows three records of a young man nineteen years old who began smoking cigarettes at the age of fifteen and who inhaled the fumes. The three records were taken without removing or readjusting the instrument, as follows : No. I, immediately before smok- ing ; No. II, during the indulgence of the habit, and No. Ill, fifteen minutes later, after the effect of the narcotic had become apparent. Now, by reference to Figure -3»>, No. Ill, we may observe how this young man's heart should record itself, for the latter is the tracing of the heart pulsations of a normal young man of the same age and temperament. Nos. IV to VI ( Figure -'■).'>) are repre- sentative of another inhaler twenty years old, who began the practice at thirteen. He now uses a strong pipe. In Figure 236, Nos. I and II, taken respectively before and after smoking, are tracings of a sensitive youth of eigh- teen who has been smoking only two years. Observe the 228 THE NERVOUS SYSTEM OF MAN Figure 235. skip of his heart beat at x and the corresponding partial skip under the stimulus of smoking in No. II. No. Ill (Figure 236), as mentioned above, is a tracing of a strong healthy heart of a young man of somewhat excit- able temperament. No. IV represents the phleg- matic temperament, that is, a person who is cool and calculating. No. V is the heart tracing of a strong and healthy young woman. In Figure 237, Nos. I and II are the pulse records of a man of splendid physique, thirty-six years old and weighing 230 pounds. No. I was taken before and No. II after smoking a cigar. He does not inhale. His pulse responded readily to the stimulus, but as the first tracing indicates he does not seem to suffer from any heart prostrations be- tween indulgences. No. Ill is the record of a person whose vitality is temporarily low from nervous fatigue. No. IV is the record of a young woman who was on the verge of nervous prostration. No. V is representative of a heart weakened by long indulgence in the smoking habit. The young man in question began early and continued the Figure 236. SMOKING AND SCHOLARSHIP •2-l\) practice till his physician convinced him of the extreme danger threatening his life. The pulse wave is nearly normal in length, but is entirely too weak. Under such conditions of heart a man is capable of Little courage or aggressiveness. Figure 237. "From the foregoing evidence we are led to the con- clusion that in the case of boys and youths cigarette smoking is very dele- terious to the physical and mental well-being. Moreover my investiga- tions indicate that it makes very little dif- ference in the effects whether the victim uses pipe or cigarettes, pro- vided he inhales the fumes ; and with few exceptions the young smokers are inhalers. The ordinary case exhibits about the following type of conduct : (1) While the craving is at its height the victim manifests much uneasiness and often much excitation. (2) During the indulgence the cheek is alternately flushed and blanched, the respiration considerably increased and the hands tremble. (3) About twenty minutes after smoking the muscles become relaxed. the respiration slow and shallow, the skin on the face dry and sallow and there is an apparent feeling of unconcern about everything." — W. A. McKeeveb. 172. Smoking and Scholarship. — Several thousand boys have been studied and classified according to acre and whether they were smokers or non-smokers. In all cases the non-smokers had a higher average grade of scholar- ship. The experience of city superintendents and prin- 230 THE NERVOUS SYSTEM OF MAN cipals is that they can usually tell a cigarette boy by his general attitude, poor scholarship, and disregard of per- sonal appearance. When cigarettes are burned, three distinct poisons are produced, which cause serious effects on the boys who use tobacco in this form. These poisons are absorbed in small quantities by the mucous membrane which lines the nasal passages and in larger quantities when the smoke is in- haled in the lungs. A simple way to prove that cigarette smoke contains a poison is by blowing the smoke through a glass tube into an aquarium containing goldfish. Only a small amount of smoke wrill kill the fish. While we can all gradually adapt ourselves to small amounts of poison, poisons are never beneficial unless pre- scribed by a physician to try to remedy some bodily defect. The poisons which arise from the burning of a cigarette are never prescribed even as medicines, and have never been found in any way beneficial to the human body. SUMMARY The nervous system of all vertebrates consists of a brain and spinal cord with nerves passing to all organs of the body. The brain of man is the most highly developed. All our movements are controlled by means of the nerv- ous system. Through our sense organs we gain our information of the world. The nervous system is made up of cells which are highly specialized. Their main work is to transmit and interpret stimuli. The nerves of man are so highly spe- cialized that all stimuli which affect the eye are thought 1 > v us to be light stimuli ; or all stimuli which enter in the ear, seem to be sounds. The information which passes over any of our special sense organs travels over several QUESTIONS 231 different nerve cells before it reaches the place in the brain where it is interpreted. The highly specialized nervous system and sense organs grow and arc fed just as muscles or skin grow and are fed. There is n<> Bpecial food which we can eat that is used exclusively by the nervous system. QUESTIONS What is the nervous system? Of what parts is it composed? What animals have you studied that have a nervous system ? Which ones lacked a special nervous system? How docs the nervous system grow? Describe the nerve cell. How docs it differ from other cells in man? What are special senses ? What kind of information do you receive through your eyes? What kind through your tars ? Which d<> you remember? (The well-trained mind remembers equally well the information that comes in through each of his sense organs. ) To most of us it is given to play an unimportant n">l<' in the period in which we live. Inheriting from our parents healthy, normal bodies we can at least pass on this priceless heritage to our children. It will be their chief pride, as it is ours. Life is not easy, and we need the best bodies, the best nervous systems, ami tin* besl trained minds that it is possible for us to have in order to make our lives count for the most. This means that it is the duty of every boy and girl to know about sani- tation, public and private hygiene, and disease. REFERENCES Cutten, The Psychology of Alcoholism. Davenport, Heredity in Relation to Eugenics. Guyer, Being Well-born. Horsley and Sturge, Alcoholism and the Human Body CHAPTER XIX * THE BIOLOGY OP DISEASE1 STUDENT KEPORT How many in the class have been sick during the past year ? Of how many different diseases ? What was done to aid each one in getting well ? What was done to prevent others from taking the same diseases ? What was done by your Board of Health officer ? (Consult the reports of the State Board of Health and of the local health official.) 173. Disease. — Usually people go through their daily occupations without feeling pain or bodily discomfort. Such a condition is known as health. Sometimes, how- ever, they go about their usual duties when they do not feel well and the indisposition gradually passes away. But in other cases the ill feeling becomes severe, the usual activities are given up, and we say that they are sick. Sickness may last for only a short time or for many years. The usual conditions of the body are changed, and we say that the body is diseased. The apple, the tree, the dog, the horse, each has its own diseases. 174. Cause of Disease. — While there are many causes of disease, all of them may be grouped under four headings: (1) Inherited diseases, i.e. those transmitted from parent to child, as certain forms of insanity and imbecility where the exact cause is not known. (2) Diseases caused by such poisons as lead, arsenic, mercury, phosphorus, opium, cocaine, alcohol, and the like. The disturbances which these chemical agents set up in animal tissues are 1 Chapter XXII, Bacteria, may be read in connection with this chapter. 232 COMMUNICABLE DISEASES 233 easily recognized by a good physician. (3 ) I diseases which cause certain tissues to take on an abnormal growth, as in tumors and cancers. (4) Diseases caused directly or indirectly by some definite living plant or animal. Such diseases are called " biological diseases," because the source or cause is in all instances some definite living plant or animal. In our ordinary daily speech we often speak of such ills as " germ " diseases. 175. Biological Diseases. — The rattlesnake secretes a poison which is forced through fangs or hollow teeth into the blood of its prey. This poison affects the heart and may result in death. One of the common and beautiful mushrooms produces a similar poison which is nut de- stroyed by cooking. If this particular mushroom is eaten, death is almost certain to follow in from twenty-four to forty-eight hours. In both of these cases the animal or plant is large enough to be seen and easily recognized. But there are a considerable number of microscopic plants and a few microscopic animals that have formed the habit of living for at least a part of their life in other plants and animals. During this time, as we have seen in the study of animal parasites, they usually secure all, or the greater part, of their food from the plant or animal in which they are living. Two general causes of disease re- sult from this parasitic habit. The parasite may destroy certain cells of the body, or the material thrown off from the body of the parasite may act as a specific poison. 176. Communicable Diseases. — The term communicable disease 1 is used in this book to mean the diseases caused by 1 New York State designates t be following as communicable diseases: anthrax; chickenpox; cholera, Asiatic: diphtheria (membranous croup); dysentery, amoebic and bacillary ; epidemic cerebrospinal meningitis; epidemic or streptococcus (septic) sore throat: German measles: glanders; measles; mumps; ophthalmia neonatorum; para-typhoid lever: plague; poliomyelitis, 234 THE BIOLOGY OF DISEASE a plant or animal living as a parasite in plants, animals, or man. These diseases are communicated in various ways from one individual to another, from one animal to an- other, or from one plant to another. The following are among the most common communi- cable diseases. Diseases caused by bacteria (minute plants) are tuberculosis, pneumonia, diphtheria, typhoid fever, bubonic plague, and whooping cough. Measles and scarlet fever are so similar to I these in many ways that it is believed that they are caused by ^_ ^^ bacteria, although the ^_ ^^ definite bacteria which cause them have not been discovered. Dis- eases caused b}^ proto- ■ ? rp -a o wi zoa (minute animals) Diphtheria Measles Tvphoid Scarlet Whooping ^ ' fever cough are malaria, yellow Figure 238. — Deaths from Communicable fever sleeoina" sick- Diseases. ' ,* ° , , ness, possibly small- This is for the year 1913 in New York r J State. pox, and others less well known. The biological diseases are all preventable, especially the communicable diseases which result from the parasitic habit of some plant or animal. In order to prevent these diseases, it is necessary to know how the different plants and animals gain access to the human body and proceed to live there. This can be illustrated by describing pul- monary tuberculosis, a plant or bacterial disease ; and malaria, an animal or protozoan disease. acute anterior (infantile paralysis); puerperal septicaemia; rabies; scarlet fever ; smallpox ; trachoma ; tuberculosis ; typhoid fever ; typhus fever ; whooping cough. Robert Koch (1843-1910) was a celebrated German physician, noted as the discoverer of the bacilli of tuberculosis and of cholera. In 1882 he announced in Berlin the discovery of the tubercle bacillus, and the same year he published a method of preventive inoculation against anthrax. Later he discovered tuberculin, a substance intended to check the growth of the tubercle bacillus. In 1883, Koch led the German expedition to India to investi- gate cholera, and discovered the cholera germ. In 1885 he be- came Professor of Medicine at Berlin and in 1891 Director of the new Institute for Infectious Diseases. PULMONARY TUBERCULOSIS 235 177. Pulmonary Tuberculosis. — Pulmonary tuberculosis is a disease located in the lungs. The cause is ;i definite plant with parts and habits which are easily recognized by bacteriologists (students of bacteria). This plant is called Bacillus tuberculosis, and was proved to be the cause of consumption, or tuberculosis, by Robert Kocli, a German scientist, in 1882. These tuberculosis bacteria, or germs, in countless numbers are found leading a parasitic life in the lungs of a tubercular patient. The bacteria are ex- tremely minute, and can be seen only by the use of a microscope of high power. The large number of germs in the lungs grow rapidly and they are set free in the air by coughing. One tuber- culosis patient may give off millions of these germs in a day. For this reason great care should be taken in destroy- ing the sputum of patients, for if the germs become dry. they are carried about as dust particles. Tuberculosis and other disease germs are so numerous that it is impossible to escape taking some of them into our bodies, but they usually do us no harm unless we are in a weakened condition. Modern methods of cleaning the streets by flushing witli water, keeping garbage covered, and wiping up tin- dust in our homes instead of using the old-fashioned feather duster are doing much to keep down the number of germs in the air which we breathe. The bacteria that are breathed in from the air may find some weak place in the lungs in which to take up their parasitic lives. Those which enter on the food pass from the digestive tract into the blood and are eventually carried to the lungs. The introduction of tuberculosis germs in this way is especially frequent in children. In many cases milk from tuberculous cows is the source of the disease germs. See § 248, page 34(.*. 236 THE BIOLOGY OF DISEASE The cause of pulmonary tuberculosis is, then, the tuber- cle bacillus, which is taken into the lungs in the air we breathe, or through the food eaten, or by personal contact with a consumptive patient. These germs cause certain parts of the lungs to become diseased. 178. Getting Well. — Consumption is not necessarily fatal, especially if treated in its earliest stages. But many Figure 239. —Tuberculosis Cure, Summer. people who have the disease do not consult a regular physician until it has made considerable progress, and then it is too late to bring about a cure. Figures 239 and 240 show the present method used in treating tuberculosis. The patients are given tissue-build- ing food (protein) and are required to sit and sleep out- of-doors as much as possible. Rest, good food, and fresh air work wonders in arresting the progress of this disease. When the body gains the requisite amount of strength MALARIA. A PROTOZOA X DISEASE 'IM the disease and its germs are usually thrown off. Patent medicines and alcohol should be avoided, as they reduce the power of the body to resist disease and give no aid in building up the diseased tissues. In addition, alcohol causes serious disturbances in the general circulation. Figure 240. — Tuberculosis Cure, Winter. In addition to pulmonary tuberculosis physicians recog- nize tuberculosis of the throat, intestines, kidneys, brain, and joints. 179. Malaria. A Protozoan Disease. — Malaria is a disease caused by a protozoan or minute animal which is dis- tributed over the greater part of the world. The malaria protozoan is a minute simple cell of living matter. It resembles the amreba in its form and ability to chancre. This parasite penetrates into the red blood corpuscles and remains in them for twenty-four or forty-eight hours, or until the substance of the corpuscle is nearly used up. 238 THE BIOLOGY OF DISEASE Then the parasite escapes into the plasma of the blood and later enters a fresh corpuscle. 180. Source of the Malarial Parasite. — The word malaria means bad air, for it was formerly believed that foul air caused the disease. When it was learned that a definite animal was the cause both in man and in other animals, the problem was to find how the parasite entered the bod}^ Figure 241. — Malarial Swamp. An ideal place for mosquitoes to breed. ] It has been proved to the satisfaction of scientists that the malarial protozoan is injected into the blood by a particular kind of mosquito (Anopheles) which carries malaria germs in its body. The mosquito sucks the blood from a man or an animal suffering from malaria. This blood contains some of the malarial parasites, which pass into the stomach of the mos- quito. They then migrate into the salivary glands of the mosquito, so that as soon as the mosquito bites another man or animal, it pours out some saliva which intro- duces the parasites into the victim's blood. While in the PREVENTION OF COMMUNICABLE DISEASES 239 body of the mosquito, these parasites pass through definite stages in their life history; and when they reach tin- blood of man, the remaining stages are completed. Thus a man, or an animal, and a particular mosquito are neces- sary for the complete life history of the malarial parasite. This means in addition that for the prevention of malaria all that is necessary is to destroy the Anopheles mosquito, or in case this cannot be done, to screen ade- quately the houses, tents, and bedrooms in the regions where the mosquitoes live. It is interesting to note that this discovery of the cause of malaria and the methods for its prevention was more than anything else responsible for the successful completion of the Panama Canal. The con- struction of this important work was more a health than an engineering problem. 181. Other Protozoan Diseases. — Other protozoan dis- eases are produced in the same manner as malaria. The carrier may be different, but the principle of spreading the diseases is the same. Yellow fever, for instance, is spread by another kind of mosquito, and sleeping sickness by the tsetse fly. 182. Hookworm Disease. — This disease is caused by a parasite which is classified as one of the worms. Hook- worm disease belts the earth in a zone which extends thirty - three degrees each side of the equator. Great progress is being made in the United States in curing those su lin- ing from this disease. The wearing of shoes and the use of a sanitary closet are usually sufficient preventives bo protect the people who live in a hookworm district. 183. Prevention of Communicable Diseases. — The pre- vention of these diseases depends upon an understanding of the causes which produce them, close adherence to the laws of hygiene, and especially the exercising of proper care in the production and cooking of our food. Germ 240 THE BIOLOGY OF DISEASE diseases are unnecessary, and it should be considered a disgrace to a community if some of them appear. Proper hygienic measures will do much towards eliminating most of the communicable diseases, but until the intelli- gence of communities can be aroused enough so that such measures shall be insisted upon, we must depend upon proper food, rest, fresh air, and exercise to keep ourselves fit, and thus avoid the conditions which help disease to ■ TLa ■ .hu'.ihlT^*j< _^0 * - ___ — ■ ■ . ■ K ^H '■ 1 Figure 242. — A Model Reservoir. gain a foothold. Tuberculosis, for example, is more likely to occur in persons who are underfed and overworked, and a cold often follows an attack of indigestion. Care of Food. — The care of food is extremely neces- sary in preserving our bodily well-being, for the same germs live and grow in food which cause disease when taken into our bodies. One method of keeping the bac- teria on food from growing is by proper refrigeration. The temperature of a well-cooled refrigerator does not destroy the germs, but makes them incapable of growth until heat is supplied them. So if food is taken from the refrigerator and allowed to stand for a time, the bacteria will at once begin to grow and cause the food to spoil. PREVENTION OF COMMUNICABLE DISEASES 241 If such food is eaten, an intestinal disturbance usually results. In the attempts to prevent disease, more study has been given to milk and water than to other foods. For discus- sion of milk, see pages 347-350. While milk is used as a food by all mankind, water is even more important, for it is absolutely necessary if we Figure 243. — A Poor Reservoir. Note the open stream that empties into the main body of water. The impure water of the Erie Canal drains into this open stream. are to continue to live. In this respect man is like all plants and all other animals, water being necessary for the preservation of all life. Two conditions must be met before a water supply can be deemed satisfactory. There must be an abundant supply; but more important still, the water must be pure, that is, free from disease-producing germs. Farmers and residents of small towns ma}r without great trouble secure sufficient pure water, but the large cities have to spend millions of dollars in providing an adequate water supply. 242 THE BIOLOGY OF DISEASE Sanitary measures are adopted to keep the sources of the water from becoming impure, as well as to keep clean the reservoir where it is stored. Certain harmless plants and animals living in reservoirs may give an unpleasant taste or odor to the water. Harmful disease germs live in water for months. Such germs may be frozen in ice, stored in ice houses, and when later put with the ice into drinking water, may cause typhoid fever. It is, therefore, important that we have plenty of pure water, and we should do all we can to help in giving the town or city in which we live a pure water supply. Introduction of Antitoxin Treatment STUDENT REPORT Prepare a report on the water supply in your locality and find where it comes from. What measures are taken to keep the sources and reservoir clean ? 184. Keeping Well. — Our best doctors are spending much effort in showing how to avoid disease, for no one is benefited by illness. The old notion that children should be exposed to measles, scarlet fever, and whooping cough is wrong, for none of these childhood diseases is necessary. The time will come when our homes and surroundings will be so sanitary that the common diseases caused by germs will be elimi- nated, or at least decreased in number. Government inspection of meats is lessening the amount 1881 87 89 91 93 '95 '97 1900 02 04 06 08 10 12 14 Figure 244. — Diagram. Thirty years of diphtheria in New York State. KEEPING WELL 243 of disease contracted from eating diseased pork, incut, and fish. The United States Department of Agriculture is making every effort to inspect such products, and tin- department is fairly successful in inspecting the larger establishments. However, many cattle and hogs are killed and sold locally and they escape inspection, so that buyers IF THESE CASES THESE CASES HAD BEEN REPORTED WOULD r^VER MAVE OCCURRED JO 25 3l5 S Ct |:0 *■ On Fabm On Faom J I 1J M 17 21 30 I 2 4 6 6 10 12 14 16 « 20 Mm S 7 9 II 13 15 17 19 June 21 . , 27 9 II M 17 21 30 I 2 4 6 6 10 12 14 16 « 20 23 JO Afri Mm 5 7 9 ll 13 15 17 19 T The Story of the Epidemic op Septic Soke Throat at Rockvoxe Centre. L. I. Figure 245. of this meat have no protection against a general condition of disease. Another danger to health is from the people known as "carriers" of disease, as such people give no evidences of illness. Typhoid and diphtheria are the two diseases most likely to be carried in this way. Many of these carriers serve as cooks, and as they give no evidence of being in other than perfect health, they often spread the germs through the food they prepare. If habits of abso- lute cleanliness are insisted upon, much of the danger of the dissemination of srerms in this way will be removed. 244 THE BIOLOGY OF DISEASE Many hotels, public institutions, and well-run house- holds insist that a prospective servant shall be examined by a competent physician before being engaged for work. In this way carriers may be detected, and persons with germ diseases, like tuberculosis, for instance, are pre- vented from spreading disease either in the food or in the air. ( hildren in the schools frequently have diphtheria germs living in their nasal passages or throats, but are not ill. After a time a number of children come down with the dis- ease. A doctor then takes a sample of the contents of the throat and nose of each child. The bacteria in the mucus from the nasal passages is allowed to grow for twenty-four hours in a special preparation called a culture (page 346). At the end of that period the cultures are stained and ex- amined with a high power of the microscope, and if diph- theria germs are present, they are easily seen. If one of the well children has these germs, he is treated until they disappear. 185. Quacks and Patent Medicines. — The term quack is applied to a person who advertises that he can cure vari- ous diseases by some new invention or newly discovered remedy. A patent medicine is one which has been regis- tered at the patent office, and this registration gives the patentee exclusive right to the use and name of the so- called remedy. Many millions of dollars are spent an- nually in advertising special " cures " and new mechanical contrivances guaranteed to cure diseases for which they can do nothing, or even to cure such diseases as cancer, for which there is no known remedy. Many people who do not understand the causes of dis- ease are reluctant to consult a well-trained physician, but read and believe the carefully worded advertisement of some quack doctor or of some patent medicine. The ALCOHOL AND DISEASE 245 untrained sufferer cannot interpret the meaning of his distress and is incompetent to select the proper medicine. As real medicine is given for specific symptom- associated with a specific disease, it is apparent that ;i patent medi- cine advertised to cure from six to forty diseases is worth- less. Furthermore, real medicine is given to relieve a certain set of symptoms at a given stage of the disea and is frequently changed. This is, of course, impossible when using a patent medicine. If every one would eon- suit regular physicians, and cease patronizing the quacks and patent medicines, one of the sources of much sickness and suffering would be destroyed. 186. Alcohol and Patent Medicine. — Repeated chemical analysis of many of the patent medicines shows that they contain a considerable amount of alcohol. There are over 120 patent medicines which the United States Government will not permit to be sold except by the possessor of a liquor license. This fact alone shows the harmful nature of patent medicine. 187. Alcohol and Disease. — It is unnecessary to make an elaborate series of quotations from eminent men to prove that alcohol is not useful and necessary as a medicine in the cure of disease. One of the chief reasons has already been given in connection with the discussion of tubercu- losis. There is no evidence that alcohol has any effect "ii the destructive course of a disease, or any beneficial effect upon the person suffering from disease. This last phase of the problem has been under critical study Long enough to show that the earlier claims of the helpful- ness of alcohol in disease are not supported by the facts. The reverse is true. Alcohol is known t«> decrease the power of the body to withstand disease and dm>s not assist in destroying the poisons which arise in the case of bacterial diseases. At present there is no 246 THE BIOLOGY OF DISEASE scientific evidence which justifies the use of patent medicines, or of alcohol unless definitely prescribed by a physician. 188. Headache and Anti-pain Patent Medicines. — Many preparations advertised under these general names are taken by persons ignorant of the fact that these medicines generally contain harmful drugs. It should be sufficient to know that no reputable doctor will ever give any of these preparations except in a mild form, and in case of extreme pain. No person except a trained physician has a right to prescribe drugs ; and he only after a knowledge of the patient's symptoms. Many of these preparations affect the heart and blood, and none of them has any beneficial effect on the real cause of the pain. 189. Boards of Health. — Communities and physicians have endeavored to prevent the spread of communicable diseases by the formation of boards of health, by quaran- tine, vaccination against smallpox, immunization against typhoid fever, the use of antitoxin in diphtheria, disin- fectants and fumigants. The term Board of Health is applied to a number of individuals, appointed or elected by a nation, b}^ a state, or by a community, to enforce the national, state, city, or town health laws and regulations. The local officer of this board is a physician, and in some states, New York for example, is appointed according to the regulations governing the city or town in which he is to serve. The New York state law defines his work as follows : " Every such local officer should guard against the intro- duction of such communicable diseases as are designated by the State Department of Health by the exercise of proper and vigilant medical inspection and control of all persons and things infected with or exposed to such diseases, and provide suitable places for the treatment and QUARANTINE 247 care of sick persons who cannot otherwise be provided for."1. Violation of quarantine and of the various health regu- lations, such as the pollution of water and improper care of refuse and sewage, should be reported to the local health officer. In case no satisfactory results are obtained from the local health officer, the question may be referred to the Figure 246. — Model Dairy Cow. State Board of Health, which gives prompt and efficient attention to all questions concerning the health of the people of the state. 190. Quarantine. — When a person or a group of persons is suffering from a communicable disease, or when anyone has been exposed to the germs of the infection of any such disease, the Board of Health may place him under quarantine. The nature of the quarantine depends OD the JThe Sanitary Code of the Public Health Council of the State of NYw York defines the health officer's duties in detail and may be had by writing to the State Department of Health at Albauy. Selections from the Sanitary Code will be found in Appendix B. 248 THE BIOLOGY OF DISEASE specific disease and the laws of the town or state in which the persons reside. The New York law on this subject is typical of the best state laws on quarantine. It says : "The Board of Health shall prohibit and prevent all intercourse and communication with or use of infected premises, places, and things ; and require and if necessary Figure 247. — Model Dairy Stable. provide the means for the thorough purification and chang- ing of the same before general intercourse with the same or use thereof shall be allowed." See Appendix B. This means if an individual is suffering from scarlet fever or diphtheria, or some other communicable disease, he shall not associate with the general public until he has ceased to be a source of infection. His liberty is tempo- rarily restricted by quarantine because he may be the cause of sickness and even death to others by spreading the germs of communicable disease. It is interesting to know that the more highly civilized QUARANTINE 249 00 D O a; SZ JZ o n- 4) To ,c o a nation, state, or city becomes, the more specific and exacting are the quarantine regulations. There is every reason to believe that in the near future the present laws 250 THE BIOLOGY OF DISEASE of quarantine will be extended. In addition to individuals being quarantined in a dwelling, all the inhabitants of a city or state may be quarantined in case of severe epi- demics ; or the transportation of stock from one state to another may be prohibited in the case of a serious com- municable disease existing in cattle or sheep. The quar- antine laws, for example, order from time to time that all dogs in the town or county shall be muzzled as a protective measure against rabies. Immigrants suffering from certain diseases are prohibited from landing in the United States. This means that there are national as well as state and city quaran- tine laws. The present quarantine laws are the most effective protective measures against the spread of disease known to man and are the product of a high degree of civilization. 191. Vaccination. — The success which has attended the efforts of man to overcome disease is well illustrated hy smallpox. For centuries this disease was responsible for many deaths throughout the world. It is said to have existed in China centuries before Christ. Later it swept over Europe again and again. King Frederick William III of Prussia stated, in 1803, that 40,000 people suc- cumbed annually in his kingdom. A famous French physician wrote in 1754 that every tenth death was due to smallpox, and that one fourth of mankind was either killed by it or disfigured for life. Smallpox was brought into the Western Hemisphere soon after the discovery Figure 249. — Agar Plates. Where a house fly was allowed to walk White patches are bacterial growths. VACCINATION 2.->l of America and killed thousands of the Indians. It also visited the colonies. In 1721, Boston was ravaged foi the sixth time by this disease. Out of the 10,567 Inhabit- ants, 5989 had the disease and 894 died. In 179G, Jenner, an Englishman, demonstrated the fact that by inoculation of a person with cowpox, a disease peculiar to cows and in some way allied to smallpox, the patient would become immune to the dreaded disease. This was one of the greatest and most beneficial discoveries of medi- cine which has ever been made. By the result of vaccination small- pox has become a rare disease in the civilized nations of the world, and is least prevalent where the vaccination laws are the most stringent. Vaccination for smallpox consists in the inoculation of the human patient with vaccine, a substance secured from a cow sufferings from O cowpox. This usually causes a slight illness, but during the illness the patient acquires a power which enables him to resist the germs of small- pox. This acquired power of resistance is called im- munity. Many people do not understand the theory of vaccina- tion and its advantages, and have opposed its use through fear of acquiring lockjaw from the vaccine. It has been established that proper vaccine matter never contains the germs of lockjaw, and if this disease occurs, ii is due to failure in keeping the arm clean during the period when the vaccination scar is forming. Immunity to disease is now being produced through inoculation. The patient is inoculated, that is, there is Figure 250. — Bacteria and Mold. One tenth of the num- ber carried by one house fly. 252 THE BIOLOGY OF DISEASE introduced into his circulatory system a virus, or serum. Each disease has its own virus, as the vaccine in small- pox, and this virus produces a mild form of the disease. This causes the cells to become resistant to the germs or microbes of the specific disease. Inoculation is being widely used for the prevention of typhoid fever. All soldiers are required to take this treatment. It would be desirable for all people to become immunized against this disease, but those who travel extensively and thus have to drink all kinds of water and milk should certainly undergo this treatment. Vaccination and im- munization reduce the liability of death in case the disease is acquired, but they do not ab- solutely prevent the disease. If a vaccinated or immu- nized person gets an overwhelming number of germs, he may have an infection of a slight kind. But the liability of contagion is reduced to a minimum. 192. Antitoxin. — We cannot say definitely why vaccina- tion and immunization act as they do. It is known that if a poison (toxin) produced during a case of diphtheria is gradually introduced into the blood of a horse, a sub- stance is produced which destroys the injurious effects of the diphtheria poison. The serum from the blood of the horse is called antitoxin, and may be preserved for use at any time to destroy the influence of the diphtheria poi- son. A given amount of this antitoxin is introduced into the blood of the patient suffering from diphtheria, and this usually counteracts the disease. This treatment has Figure 251. — Milk Diluted to j-^- Left-hand culture from clean milk ; right-hand culture from dirty milk. DISINFECTION AND DISINFECTANTS 253 saved countless lives. It is estimated that in the ten years after the discovery of the diphtheria antitoxin the lives of a million children were saved in Franc- alone. State boards of health usually furnish antitoxin for diph- theria and lockjaw. LABORATORY STUDY It takes five pounds of sulphur to disinfect a room which contains 1000 cubic feet of air. Three ounces of forty per cent formalin, u> which is added two and one tenth ounces of potassium permanganate will also disinfect the same sized room. Compare the cost and ease with which each is used. 193. Disinfection and Disinfectants. — The time when dis- infectants shall be used and the manner of disinfection have been considered important factors in preventing the spread of communicable diseases. The purpose of <1 ^in- fection is to. destroy the germs lodging on clothes, floors, carpets, and curtains. People who care for the sick should know where the germs are likely to be and how to disinfect places where they have found lodgment. The term disinfectants is sometimes incorrectly applied to deodorizers, substances which are used to destroy odors, but the word should be applied only to substances which destroy germs or bacteria. Disinfectants are not expensive, and few of the patented preparations are as satisfactory as the common ones used by boards of health. Weak solutions of carbolic acid and bichloride of mercury are chiefly used for killing the germs on the hands and clothing, or f»»r cleaning tin- woodwork in the sick room. Chloride of lime is used to kill the germs in the discharges of the body, and Bulphur dioxide and formaldehyde gas for the final killing of the germs in the room or the whole hoitse before it is occupied again. 254 THE BIOLOGY OF DISEASE Never use any methods of disinfection unless they have been personally recommended to you by a physician or an expert in the details of room disinfection. Do not rely upon patented solutions and methods. The latter are ex- pensive and often practically worthless.1 194. Results of Disease. — In New York State for the year 1909 there were reported to the State Board of Health 138,315 cases of communicable diseases. There were many. cases that were not reported, so that this is not to be taken as the highest estimate of the number of people who were sick with preventable diseases. During the years 1913, 1914, 1915 in the same state the following number of people died from these communicable diseases. NUMBER OF DEATHS 1913-1915 1913 1914 1915 Diphtheria 1853 2015 1754 Scarlet Fever 837 687 409 Whooping Cough 818 730 749 Measles 1071 839 834 Typhoid Fever 1018 878 750 It is difficult properly to measure the value of health to the community. When the wage earner is sick and is placed in quarantine, the loss of money is the amount he might have earned. In the case of a typhoid fever epi- demic the total loss is many thousands of dollars. Further, there is no adequate measure of the sufferings of those who die, and the heartaches of those who survive. But both the suffering and the financial loss can be greatly lessened by improving our sanitary laws and aiming at a better state of health for all the people. An increase in 1 When practicable, it is well to have the local health officer discuss such subjects as disinfection and quarantine. IMMUNITY 2f)5 taxes to provide cleaner streets, public playgrounds, proper sewage disposal, and adequate inspection of milk, meat, and water, is really an economy. For although such improvements cost money, they are not so expensive as epidemics of disease and the maintenance of hospitals and of orphan asylums. 195- Heredity of Disease. — The term heredity of disease is one which has been misunderstood by many people. By the term heredity we mean that which is handed on from parents to their offspring. In the case of biological diseases which are caused by some definite' plant or animal, it is evident that they cannot be inherited. But when t la- parents are afflicted with a biological disease, their bodii is become weakened and their offspring may have a poor constitution so that they are more easily affected by disease. 196. Immunity. — Immunity is a technical term which means that the body resists or is not susceptible to the germs of biological diseases. Many people do not become sick when there is an epidemic of typhoid fever, measles, malaria, or the like. Such people are said to possess a high degree of natural immunity to disease germs. People usually well frequently take germ diseases when the body happens to be exhausted by care or work. In such cases the immunity of the body has been weakened. Many of the germ diseases confer immunity against a second attack of the same disease, but tins does not hold true for all persons or for all germ diseases. Vaccination a gain si smallpox, in the case of most persons, confers immunity for about seven years. Inoculation with the typhoid serum confers immunity for from two to three years. Im- munity, then, is a relative term, and depends in a large measure on the state of health of the individual and on his power of resisting the poisonous effects of disease germs. 256 THE BIOLOGY OF DISEASE Student Report Due to Some Plant or Animal Treatment by Prevented BY 4J a> s In the watei o C3 3 o s 5 u to CD 3 "3 <33 C O ^— eS O ■ji t the new plant; (3) the hypocotyl, below the cotyledons, from which the stem and roots will grow; (4) the hard covering or testa. Look for the micropyle and raphe on a bean not split. 262 TYPICAL FLOWERING PLANTS Figure 255. — Diagram of Corn Seed. 201. Corn -'Seed.'' — A grain or kernel of corn, com- monly called a seed, is like a bean (1) in containing a young plant, the corn embryo ; (2) in containing food for the use of the embryo when it first begins to grow ; and (3) in having marks upon it. On the top of the kernel is a slight prominence, the scar which marks the place where one thread of the so- called silk was attached. On one side of the kernel is a depression beneath which the embryo lies, and at the base is a stalk by which the kernel is attached to the cob during its development (Figure 255). A corn grain differs from a bean in being a fruit, — that is, the seed case adheres to the seed coat as a second covering. A kernel of corn, therefore, corresponds to a bean pod containing but one seed. Corn differs from the bean also in the position of the embryo, which is at one side of the food supply. The latter is called the endosperm (en' do- sperm : Greek, endo, within ; sperma, a seed). Another dif- ference between the two is that the corn has a single modified cotyledon called the scutellum (sku- tel'lum : Latin, diminutive of scutum, a shield), the use of which is to absorb and digest the food and carry it to the embryo (Figure 255). The cotyledon of the corn never appears above ground. The corn embryo has its leaves rolled into a tight, pointed bud, which enables Figure 256. — Sun- flower " Seed." A fruit. Figure 257. — ■ Squash Seed. CLASSIFICATIOX OF SEEDS 263 it easily to pierce the earth above. The root is at the lower part of a short hypocotyl. As the corn has but one cotyledon, it belongs to the class of plants known as monocotyledons (moii-o-kot-v-lr'- don : Greek, mono, one ; kotyledon, socket). The bean, having two cotyledons, belongs to the class dicotyledon* (di-kot-y-leMon : Greek di, two ; kotyledon, socket). LABORATORY STUDY WITH CORN Remove most of the endosperm from a few kernels, and plant them. How does the growth compare with that of a kernel retaining ;ill its endosperm? Examine whole corn kernels, noting (1) silk sear on top ; (2) depression on the side ; (3) hard outer covering; (4) stalk by which it was attached. Cut crosswise a kernel which has been soaked in wal and identify the embryo, scutellum, endosperm, and hard outer covering. Split a kernel lengthwise and find the same parts. Remove the embryo from another soaked kernel and study its attachment to the endosperm. Look for the plumule and root. Examine such seeds as you can obtain and make a report, using the following table as guide. Bean . Pea . Corn . Squash Etc. . Size Embryo EASILY Seen IIili M AT BlDH llll.t M OS End Two COTJ i.l - DONS ■ '■ B COTYl K- |..,N 202. Classification of Seeds. — The comparative stud\ oi the bean and corn seeds shows the important parts of seeds and explains the chief differences between them. The common seeds are classified as follows : monocotyledons: grass, wheat, barley, oats, and rye ; dicotyledons : Bquash, morning glory, tomato, radish, and beet. 264 TYPICAL FLOWERING PLANTS 203. Growth of the Bean Embryo. — As soon as the ground is warm in the spring, farmers plant beans in rows. After the bean seed has lain in the damp earth for about ten days, the moisture has softened the seed coat and food, and the shoots from the beans begin to show above the ground. The first part of the bean embryo to show is grown in the little stem (hypocotyl). This curves sharply into an arch and begins to push upward through the particles of soil. At the same time delicate roots push downward into the soil (Figure 258). As soon as the arch of the hypocotyl has pushed through the soil into the light, it straightens up and pulls the seed leaves (coty- ledons) out of the ground. The seed coats are usually left behind in the soil. As soon as the cotyledons are exposed to the light, they crack apart, slowly spread wide open, and in a few days become green. During these changes in the coty- ledons, the leaves of the plumule have taken from them the food stored for the use of the growing bean embryo. As soon as this store of food is absorbed by the young bean plant, the cotyledons drop to the ground. The bean seedling is no longer dependent on the food in the seed, but is able to gain its food from the soil and air. During the summer the bean plant grows bean seeds, and the farmers harvest the beans and store the seeds in barrels, sacks, or wooden bins. The dry beans may be kept for years and still grow bean plants at any time when conditions are favorable. a Figure 258. — Germination of Bean. FOODSTUFFS IN THE BEAN 2IW3 LABORATORY STUDY Examine germinating seeds and young seedlings »>f various kind plants, and note their peculiarities in Bprouting as indicated below. Bean . Corn . Pea . Tomato Squash Maple Etc. . Ai:< ii Pkominent Ai;i li HOI l'l'.i'MIMN I Cotyledons \ BOVK ( litoi N l> COTYLl l>>'S^ ttO I A l«i\ I < . BOUND I i - i \ Brocohi I P 204. Foodstuffs in the Bean. — The bean stores two kinds of stuffs: carbohydrates and proteins. Carbohydrate is the name of the foodstuff which includes such foods as sugar and starch. The term protein is applied to the foodstuff found in such foods as the lean of meat, the white of egg, and the curd of milk which we use as cheese. The presence of these foodstuffs may be shown by applying the following chemical tests. I >oil beans until they are soft and then place a small portion of them in a test tube. Add a drop of iodine. If starch is present, the mixture will turn purple in color. Add strong nitric acid to a second portion in a clean test tube, boil and cool. If protein is present, the mixture will be a clear yellow color which will become orange if ammonia is added. To a third portion add Fehling's1 solution as a i 1. Copper sulphate 9 grams Water 500cc. 2. Rochelle salts 49 ,i;r;iiii> Caustic potash 30 grams Water 250cc. Take two volumes of l. and one of 2, and add to the mixture 2 rolum< water. Do not mix 1 and 2 until ready to use. 266 TYPICAL FLOWERING PLANTS test for sugar. If the latter is present, the mixture will become dull orange when heated. Test uncooked seed for oil (1) by heating it over a lamp on a sheet of linen paper ; (2) by soaking it over night in ether. (This must not be near a flame at any time.) If oil is present, it will show on the paper as a clear spot, and in the second test the oil will appear on the surface of the ether in the test tube. Make a record of the results as indicated below: • Much Peotein Much Staech Oil SUGAB Bean Corn Wheat .... Walnut .... Pea • 205. Digestion of the Food in the Seed. — It may appear strange that the growing bean plant lives upon the food stored in the cotyledons, and yet such is the case. But this food must undergo a real digestion before the bean embryo can use it. We do not know just how this digestion takes place in the bean, but in the corn, as we have learned, there is a special structure, the scutellum, which helps to digest the food in the endosperm. This corn scutellum may be removed from the corn seed and made to digest other kinds of starch, for instance, that obtained from a finely grated potato. This should be kept warm and moist for several hours, after which it may be tested for sugar with Fehling's solution (See page 265). When scientists learn more about the digestive processes of plants they will probably find that they are similar to the digestive processes of animals. ROOT SYSTEM 2(37 206. The Bean Seedling — Each bean seedling is provided with a supply of food which gives it a start in life. But after this supply is exhausted, the young beao must be able to prepare its own food. The Beveral parts of the bean seedling are the roots, stem, and leaves, all of which work in preparing the seedling's food. 207. Root System. — The first root to form on the bean is called the tap or primary root and grows straight downward. Many branches, known as secondary roots, grow from the taproot. These large secondary roots serve chiefly to hold the plant firmly in place. From the secondary roots smaller branches or rootlets grow, and on these, a short distance back from the tip, are nu- merous root hairs. In order to under- stand the other great use of roots, we must be familiar with their structure. A cross sec- Figure 259. — Bean Plants. All the food these plants have used came from the cotyledons, as the jar contained only sawdust. tion of a taproot shows three regions. In the central part is a woody portion called the central cylinder. Next i«> and outside of this is a layer known as the endoderm (Greek, endo, within ; derm, skin) which separates tin- central cylinder from the next region, the cortex (hat in, cortex, bark). Outside of all is a thin protective layer, the epidermis. 268 TYPICAL FLOWERING PLANTS If we examine under the microscope a portion of the epidermis taken from near the center of an onion bulb, we find that it is made up of many small parts, called cells. Every cell consists of living matter (protoplasm) surrounded by a wall. Near the center of each cell is a small spherical body called the nucleus. See page 4. All regions of the plant body are made of such cells, and the cells of each region are adapted to the special work of that re- f-v^^^Sii^^i^^^S sdon. Therefore the cells of a 3miVfB plant body vary in size and shape, but all the cells of any one region are nearly alike. Such a group of similar cells is called a tissue. See page 5. A cross section of a taproot shows the tissues of all the layers in the plant. The cen- tral cylinder contains groups of cells called fibrovascular bundles. Some of these cells overlap in such a way that they make continuous tubes from the root, up through the stem, and into the leaves. In the leaves the vascular bundles are called veins. The cells which carry the liquids present in the plant are to the plant what veins and arteries are to animals. The inner part of a vascular bundle is made up of woody cells and is Figure 260. — Sections of Bean Root. 1, epidermis; 2, cortex; 3, central cylinder. ROOT SYSTEM 269 nucleus- epidermal celiacs Figure 261. — Root Hairs. called the xylem. These cells carry water from the root upwards. The outer part of the bundle (the phlo&m) is of a softer tissue and contains the sieve vessels which carry liquid food downward. The epidermis of the rootlets is covered with rout hairs, which are really much elongated cells (Figure 261). While root hairs help to hold a plant firmly in place, their main use is to take up water from the soil. The cell walls are thin and are lined with a thin layer of pro- toplasm. Water is taken in through the walls of the cells by osmosis (page 3). The root hairs which grow in soil apply themselves closely to particles of it, and take from them the thin film of water with which each is covered. On this account the hairs or rootlets grown in soil are much more irregular in shape than those grown in water or in moist air. Unless a plant is removed carefully, all the root hairs are broken off and remain in the ground. Another statement is frequently made in discussing the uses of rout hairs, namely, that by means of an acid which they secrete, they dissolve minerals in the soil so that they can be taken up by water and carried into the plant. This is based on the fact that a seedling grown on a polished marble plate will corrode the sur- face, and on other experiments. Researches recently made prove conclusively that root hairs do nut secrete acid. Figure 262. Cap. Root 270 TYPICAL FLOWERING PLANTS Rootlets are protected on the end by a structure called a root cap (Figure 262). This cap is made up of loose cells which are constantly formed from the inside. As fast as the outer cells are destroyed by the pushing of the root through the soil, new cells are ready to take their place. Small bunches, called tubercles (Figure 263) are found on the rootlets of plants of the bean family. The tubercles are filled with bacteria which gather nitrogen from the air, use what they need, and leave the surplus in the roots. Some of this nitrogen is used by the growing plants themselves, and any that they do not use is left in the soil for the use of other plants. Most plants take from the soil more nitrogen than they add to it, but the opposite is the case with beans and their relatives. Thus clover and other relatives of the bean are used by farmers as a cover crop or for "green manure," so called, for the sake of replacing in the soil the nitrogen which other crops have used up. The practice of rotating crops depends on the fact that dif- ferent kinds of plants use different material in the soil. In successive years crops of different kinds will grow better than crops of the same kind, unless the soil has been sup- Figure 263. — Bean Roots. Showing tubercles. THE lU.AX STEM 271 Figure 264. — Fibrous Roots of Buttercup. How do they differ from the bean roots ? plied with the used-up ele- ments through the aid of fertilizers and chemicals. When water containing minerals in solution is taken in through the root hairs, it is passed along by osmosis to the woody layer of the rootlets and thence to the primary root from which" it is distrib- uted to the parts of the plant above ground. Here it is made into food and carried by the phloem of the vascular bundle to all parts of the plant. The root system of a plant, then, serves two main purposes : to hold it fast in the ground, and to absorb water from tin- earth. In passing through the soil this water has taken up mineral substances which will enter into the plant's food. LABORATORY STUDY OF ROOTS Cut a carrot crosswise and lengthwise, and note the centra] cylinder and cortex. Cut across one of the larger bean roots, noting (1) the cen- tral woody cylinder ; (2) the softer ring surrounding it; (3) the outer epidermis. Cut a root lengthwise and find the same tissues. Examine sprouted barley for root hairs and root caps; also a radish seedling for root hairs. Stand a cut-off root in red ink for a few hours. Make a and lengthwise sections, noting what part has been stained by the ink. This shows the routes through which absorbed water travels. 208. The Bean Stem. — The bean stem is made up of three parts : (1) a central pith where food is stored ; (2) woody fiber which conducts water; and (3) a bark and an epidermis which cover and protect it. The stem aa a whole holds up 272 TYPICAL FLOWERING PLANTS the leaves to the air and light, carries water and food materials gathered by the roots to the leaves, and distributes liquid foods to all parts of the plant. LABORATORY STUDY OF A BEAN STEM Make a cross section of a bean stem and find (a) the central pith; (b) the woody ring surrounding it; and (c) the outer green bark and the epidermis. Split a stem lengthwise and identify these parts. Stand the cut-off end of a stem in red ink for a few hours ; then cut across and lengthwise, noting that the woody tissue is stained red. Compare the stem with the root. 209. The Bean Leaves. — A bean leaf consists of two parts : the stalk or petiole (Latin, petiolus, fruit stalk) by which it is attached to the stem, and the broad, green part, the blade. Petioles are longer in some parts of the plant than in others. Where are the longest ones ? What reason can you give for this? The blade of a leaf is in three parts, each of which has a prominent rib entering it from the petiole. From the rib many small branches extend to all parts of that division of the blade. The vascular bundles, or veins, are of use to the leaf, not only in carrying water to it from the root and food back to the root from the leaves, but also in giving firm support to the soft parts between them. A leaf like the bean, which has many small veins running together, is called a net-veined leaf. All dicotyledonous plants have leaves with net veins. A section through the blade of a leaf shows several dis- tinct parts (Figure 265). The outermost layer is the epi- dermis, a layer of cells without much color, which serves as a protective skin. Below the epidermis is a layer of brick-shaped cells placed on end. These are called the palisade cells. They contain green coloring matter (chloro- phyll) which is held in small bodies called chloroplasts, a THE BEAN LEAVES 273 word meaning color-bearers. The position of the palisade cells makes the upper surface: of the Leaf firmer than it would otherwise be. The arrangement of the cells in a compact layer regulates the amount of light that penetrates to the interior of the leaf and helps to pre- vent undue loss of water. Below the palisade cells are the loosely arranged cells of a spongy layer. They contain chlorophyll d! and are exposed to the oooooooo spongy layer chlorophyll lower epiaer mis •stoma air which enters through Figure 265. — Cross Siction of Bean i the holes in the lower F* epidermis. Most of the How many tissues present ? work of the leaf is done in this green tissue. Because this tissue lies in the middle of the leaf, it is known as mesophyll (mez'o-fll: Greek, mesos, middle ; phyllos, leaf). The holes {stomata) in the lower epi- dermis are more than mere holes, for they can become larger or smaller according to the needs of the plant. Seen from tin- surface, each stoma is surrounded by two bean-shaped cells, containing some chloro- phyll. These cells (Figure -''>") called guard cells, have the power of absorbing water to a greater degree than the other cells of the epidermis. When the guard cells are full of water, or turgid, the Opening between them is larger than when they are almost empty or flaccid. The size of the openings regulates the amount of air which passes in and out, and of the watery vapor which passes out. The stomata are more numerous on the under side of Figure 266. — Leaf Skeleton. Showing net veins. 274 TYPICAL FLOWERING PLANTS cells of epidermis '---stoma gu-^rd cell Figure 267. — Epidermis of Leaf. leaves which grow with the blades in a horizontal position, because there the stomata are protected from water which would interfere with their action. Leaves which are nearly upright have the stomata on both sides, and leaves like a water lily that rest on the surface of the water have the stomata on the upper surface. Stomata are both small and numerous. A dozen or more are found in some leaves in a circle no larger than a period on this page. During a season a large amount of water passes off through the stomata of any plant. The pro- cess of giving off this water is called transpiration. This pro- cess is unavoidable. The root hairs gather water almost con- tinuously, and this is carried to the leaf by the fibrovascular bundles and distributed to the cells. The mesophyll in the leaf uses the minerals which the water contains, but it does not use all of the water. This excess is cast off into the spaces between the cells (intercellular spaces), which communicate with the outside through the stomata. Usually the transpiration takes place readily, but if the outside air is not in condition to take up moisture, the cells become too full and the excess is passed off through organs (the hydathodes) at the ends of the vascular bundles. The drops of water which escape from the ends of the hydathodes are called guttation drops. Grass blades and strawberry and nasturtium leaves show such drops almost every morning in the spring. House plants like fuchsia or impatiens will produce guttation drops if covered for a few hours with a bell jar. Cool a portion of the jar later, noting what happens. Give an expla- nation of what you see. WORK OF THE BEAN LEAF 275 LABORATORY KXTKIIIMKN IS Hold the underside of a geranium Leaf against a cool window pane and note the moisture which is condensed. Try other leaves in tin- .sun.- way. With clips fasten a watch crystal to a growing leaf ami seal with vaseline. Note the moisture condensed. Try the upper side of the saim- lean Plunge a leaf into water and set the water in the sun. Do small bubbles appear on the surface of the leaf ? Where ? Take leaves of the same plant and coat with paraffin one leaf on both sides, another on the upper side, and a third on the underside. Lay them aside for a few days. Then remove the paraffin and examine all the leaves. Which is in the best condition ? Why ? Examine with a microscope the epidermis of a number of leaves bom different plants. Note the irregular epidermal cells and the stomata cells. Are the stomata arranged regularly? Hold a leaf up to the light and notice the arrangement of the veins and soft parts. Study a cross section of a fresh leaf and find : (1) the epi- dermal layer on top ; (2) the palisade layer below it ; (3) the wide, spongy layer ; and (4) the lower epidermal layer with stomata. Stand the petiole of a leaf in red ink and observe how the color spreads through the veins of the leaf. •■o' 210. The Work of the Bean Leaf. — • As soon as the bean plant gets its plumule into the air, the pale leaves unfold, turn green, and increase in size. The stem elongates, branches, and other leaves appear. Bach of these new leaves is held out from the stem or branch in a position which gives the leaf the greatest possible amount of air and light. The leaves of the plumule begin to be useful to the plant as soon as they become green. Their work is most important in the life processes of the plant. Does the bean plant respire? When an animal respires, it takes oxygen into the cells of its body ami gives off carbon dioxide. The presence of this gas is shown by forcing: the air that comes from the Lungs through a tube into limewater. The limewater becomes cloudy. This i> » a simple chemical test for carbon dioxide. If a growing bean plant is kept tightly covered under a glass disk for twenty-four hours and then the inclosed air 276 TYPICAL FLOWERING PLANTS is forced through limewater, the clear limewater turns cloudy. Thus it is shown that the bean leaves have given off carbon dioxide. The only life process which is known to produce carbon dioxide is respiration. Therefore we can say that the plant respires and that this life process in the plant is similar to the same life process in animals. See pages 3 and 15. The Manufacture of Food. — The words "manufacture of food' are often used in connection with plants. This process may be better understood by comparing it with the manufacture of some article in a factory. To manu- facture an article, there must be a building with rooms; machines, and power to run them ; and various substances, called raw materials, which are to enter into the finished product. In addition there must be a supply of water, pipes in which to carry it, and forces to move it. Be- sides the finished product, a factory always yields some waste material. When the product has been finished, it is usually packed for distribution and stored in a room to which it is carried on tracks. In the leaf factory, the cells of the palisade and spongy layer are the rooms. The machines are chlorophyll bodies, and the power is furnished by the sun. The raw materials are water, containing a small amount of mineral matter obtained from the soil, and carbon dioxide obtained from the air. The pipes in which the water comes are the fibrovascular bundles, and the stomata are the places where the air enters. The forces which move the raw material are largely osmosis, capillarity, and the suction caused by transpira- tion. The materials made are carbohydrates, in the form of starch and sugar, and protein. Waste material is oxygen. The material ready for carrying is usually in the form of sugar. The storehouse may be the stem, the WORK OF THE BEAN LEAF 277 roots, or the seeds of the plant, and the tracks for carry- ing the food to the storehouse are the sieve tubes of the Figure 268. — Germination of a Monocotyledon. flbrovascular bundles. Part of the carbon dioxide is fur- nished by the plant's own respiration. The plant takes from the carbon dioxide all of the carbon, but only a part of the oxygen, leaving some of it to be thrown r~\ ft]) "i1! off as waste. The waste oxygen thus set free by the leaf in the manufacture of food can now be used by animals in respiration. Animals are constantly setting free carbon di- oxide which plants must have if they are to make food. Animals will never be able to use up all of the oxygen in the air so Figure 269. Rootlets of Two Corn Plants. Showing how they strive for food and moisture. 278 TYPICAL FLOWERING PLANTS long as there are plenty of green plants, nor, for the same reason, will there ever be enough carbon dioxide to poison animals. Another vital process which the leaf shows is digestion. It is difficult to explain how the food is di- gested in plants, but scientists have proved satisfactorily that digestion does take place. After the food is digested, it is distributed by circula- tion. In the experiments it was shown that the plant has a vascular system, and that red ink was carried to all parts of the leaf. Evidently, then, a plant has circulation. Food to be used by the plant cells must not only be prepared by digestion and distributed through circula- tion, but each cell must take from the sap what it lacks, and build this food into living plant protoplasm. This process is called as- similation and as a result of it cells grow, divide, and grow to full size again, thereby increasing the size of the plant. Summary of the work of the bean leaf : (1) It performs respiration; (2) it performs transpiration ; (3) it manu- Figure 270. — Corn Plant. Showing prop roots. THE CORN SEED LlSd J7!» Figure 271. — Maple Seedlings. Compare with Figure 274. factures sugars and starches (a process technically known as photosynthesis), and proteins; (4; it digests some of tin- food that it has made ; (5) it assimilates some of the di- gested food ; (6) by cir- culation it carries some of the starch and protein to other parts 0f the plant and brings fresh raw materials into the leaf; (7) it gives off waste material in the form of oxygen. 211. The Corn Seedling-. — When the corn seed- ling begins to grow, its tightly rolled leaves which form the sharp plumule push up through the soil. Next the root grows. The primary root, instead of re- maining the largest, as in the case of the bean, sends off a number of branches about the same size a-> itself. Like those of the bean, these branches have rootlets and root hairs. There is little difference between the roots of corn and beans so far as their structure goes, but corn roots have neither tubercles imr nitrogen-gathering bac- teria. The first Leaves Figure 272.- M.crophotograph of of (',,rn :m' likr tl"' lilt,'r Corn Stem. ones, except in size, be- hard rind " : ifi b ro-vascular bundles £ >» '■ ' <*rJ \ ■ J> 'U \ • \ '4 280 TYPICAL FLOWERING PLANTS cause only the plumule comes above the ground. The kernel of the corn remaining in the ground shrinks as the plant grows and as the food is used. The modified coty- ledon (scutellum) dies when it has served its purpose of Figure 273. — Stem of Corn. Showing node and fibrovascular bundles. transferring to the young seedling the food stored in the endosperm. 212. The Root System of Corn. — There are many fibrous roots of small size, which extend to a distance of several feet in every direction. Besides these underground roots, the corn plant has aerial roots growing from the lower joints of the stem, and these are known as prop roots. These roots are stout, straight, some- times green, branching in the soil. They serve to hold the plant firmly in the soil. 213. The Corn Stem. — While the roots of the bean and corn are similar in structure, there are several differences in the stems of these plants. The corn stem has no central region filled with pith, but the pith makes up the greater part of the interior. Scattered through it are stringlike parts, fibrovascular bundles, Figure 274. -Elm and Older Maple Seedlings. THE CORN LEAF I'M Figure 275. — Seedlings. a, Horse-chestnut seedling ; b, Honey locust. each consisting" of xvlem and phloem, but not arranged in any regular order (Figure 273). Sur- rounding the pith is a hard rind which gives the plant stiffness. The place where a leaf joins the stem is called a node. Some of the vascular bundles of the stem pass out through the nodes and as veins continue on into the leaves. The corn stem represents the structure of all monocotyledonous plants, as the bean stem represents all of the dicotyledons which live only one season. 214. The Corn Leaf.— The leaf of the corn has no petiole, but is attached to the stem by a clasping lias.-. This base protects the •tenderest part of the stalk, which is just above the node. At the point where the clasping pari and the blade of the leaf meet, there is a collar which prevents water from running down inside Figure 276. — Older Horse-chestnut Seedlings. Note the palmately compound leaves. 282 TYPICAL FLOWERING PLANTS the clasping base. The corn leaf is long and narrow ; it curves, and has wavy edges. Veins run from the base to the tip without branch- ing, giving the parallel venation characteristic of the monocotyledons. A cross section of a corn leaf shows that it has the same structure as the bean leaf. The stomata are aided in pre- venting undue transpira- tion during dry, hot weather by the tight rolling of the leaf. 215. Other Seedlings. — All dicotyledonous plants are like the bean in having two cotyledons, but differ in other respects. Peas, for instance, do not bring their cotyledons above ground. Morning glories have their cotyledons folded in the middle ; maple seed- lings have theirs folded on each other. Many seedlings have leaves which differ in shape from those of the mature plant (Figure 271). All monocotyledonous plants are alike in hav- ing only one cotyledon which usually remains in the soil during germina- Figure 278. — Roots of Radish. tion. The first seed- Containing stored-up food. Figure 277. — Wheat Seedlings. a, grown in sunlight ; b, grown in the dark. OTHER BOOTS 283 ling leaves look more like the later ones than in the dicotyledons. 216. Other Roots. — All roots serve to hold the plant in place and to collect water. Some roots have other uses in addition. The roots of beets, turnips, carrots, parsnips, and radishes store up food the first Figure 279. A valuable food. - Roots of Beet. See also Figure 296. year of their growth. If, however, they are planted a second year, they use the stored-up food to produce fruit and seeds (Figures 278 and 279). Ivy has two kinds of roots, one in the ground, the other Figure 280. — Alfalfa Root. Compare with Figures 269, 281. and 283. 284 TYPICAL FLOWERING PLANTS along the sides of the stem to help the plant cling to its support. Roots which grow in the air are called aerial (Latin, aer, air) roots (Figure 281). Sometimes roots arise from the bottom of a stem which has been cut or broken from the main plant, as in the case of a geranium slip. Such roots are called adventitious. The willow is a tree which is easily grown from a twig, be- cause it readily forms adventi- tious roots. Most roots grow downward in soil which is well cultivated. The stimulus which causes them to take this direction is gravity, or as scientists say, they are show- ing geotropism (ge-6t'r5-pizm : Greek, ge, earth ; tropos, a turn) . Other influences governing the direction in which roots grow are the presence of water and obstacles. When a root turns in the direction which will give it the best supply of water, it is exhibiting hydrotropism (hi-drot'ro-pizm : Greek, hydro, water; tropos, a turn). When a root turns aside to avoid an obstacle it acts in response to the stimulus of touch or contact, showing thigmotropism (thig-mot'ro-pizm: Greek, thigmos, touch ; tropos, a turn). The roots of poplar, willow, and soft maple trees, in seek- ing water, often clog sewer pipes by filling them with rootlets after they have gained an entrance through a joint, a habit which renders them objectionable as shade trees. In agriculture, the soil is made fine and porous to help the roots of plants get food and moisture. Figure 281. — Aerial Roots of Ivy. OTHER STEMS ln:> LABORATORY WORK ON ROOT8 Test the roots of beet, carrot, parsnip, radish, and turnip with iodine for starch ; with Fehling's solution for sugar; with nitric acid for protein. Examine a large number of roots and report. Dandelion Plantain Carrot . Dahlia . Corn Ivy . . Roots All Ondbr- GBOTJND Roots not A i.i. Dndeb- GBOCND l'l'.IMARV Kooi - FlBBOl - Booi - I A I. BOOTB 217. Other Stems. — The stems of all plants are like the stem of the bean in the work which they do, but some stems have additional uses. The stems of such plants as Solomon's seal, dogtooth violet, and Jack-in-the-Pulpit store up surplus food. These stems are thick and fleshy, and remain underground from year to year. For this reason they are often mistaken for roots, but they can always be Figure 282. — Potato. The eyes are buds. Figure 283. — Dahlia "Roots." An underground stem which stores food. 286 TYPICAL FLOWERING PLANTS ^^^^. ^x^^H [ V ip « 1 1 \ ^ ■«► «# fl Figure 284. — Microphotograph of Sunflower Stem. recognized as stems by the buds of new leaves, or the scars of former leaves. Underground stems, called rhizomes (ri'zom) or rootstocks, send up aerial stems which live through one season. Stems like the water lily, which grow in water, have large air spaces to carry air to the roots that lie in the mud at the bottom of the water. The trunks of trees are stems. In evergreen trees (pine, spruce, etc.) the trunk puts out branches, but does not divide, and tapers from base to tip. Such trunks are called exeurrent (Latin, ex, out ; curro, to run). In the case of the elm tree and many others, the trunk itself divides again and again. Such a trunk is called deliques- cent (Latin, de, from ; liquescere, to become liq- uid). An interesting com- parison is that between the climbing and twining stems of plants, especially vines, and the sturdy trunks of trees. The morning glory is a plant Figure 285. — Cleft Grafting. OTHER STEMS 2S7 Figure 286. — Whip Grafting. which twines around some support and thus is able to gel sunlight for its many leaves. Twining plants of the same kind always curve in the same direction. In twining around any object they touch, climbing plants are responding to thig- motropism. The wild grapevine is a plant which climbs to the top of trees by means of a long, leaf- less stem. Such plants, common in the forests of tropical countries, are called lianas. Woody stems have a structure which differs from that of the soft bean stem. On the outside is the brown bark in which are lenticeh, holes which allow air t<> enter. Under this is a layer of green bark, the out» *r edge of the phloem of the vascular bundles. Between the phloem and the xvlein of each vascular bundle is a region of rapidly dividing cells, which is called the CCDnhilUH, When the \ as- cular bundles are crowded close together the cam- bium of adjoining bundles touches, thus forming a ring around the tree (Figure 284). The outer edge of this cambium layer is always turning to phloem, and the inner to xyleni. A woody twig like the horse-chestnut (Figure 290) has Figure 287.- — Budding. 288 TYPICAL FLOWERING PLANTS :^=~ Figure 288. — -Twining Stem of Dodder. Figure 289. — Creeping Stem of Trailing Arbutus. a bud at the end called a terminal bud, and along the branch are other buds, named lateral buds. These buds are covered with scales and contain the leaves of the next season arranged in a definite manner. Sometimes buds Figure 290. — Horse-chestnut. OTHER STEMS 289 Figure 291. — Types of Twigs. a, maple; b, elm; c, walnut; d, catalpa e, ash ; /, linden. contain both leaves and flowers. As a bud opens, the scales drop off leaving on the twig scars crowded together in indistinct rings. The growth of a twig in the preceding year can be seen by noting the dis- tance between the tip of the twig and the first group of indistinct rings, which marks the posi- tion of the terminal bud of last year. A study of the buds on a branch shows where the new branches will form. The place where the leaves of last year were attached shows on the bark as scars, called leaf scars. In each leaf scar are a number of small dots. These dots are the ends of the vascular bundles which grew from the stem into the leaf. A cross section of a woody stem shows a central pith surrounded by one or more rings Figure 292. — Cherry Twigs. Leaf buds and fruit buds. Figure 293. — Sections of Woody Stem. of wood. The pith and the bark are connected by narrow lines of pith called medullary rays (Figure i?(.*3). A 290 TYPICAL FLOWERING PLANTS 4 V 4ij=p >J.;»Jf woody layer examined under a microscope shows large cells on the inner side of each layer, and smaller, thick-walled cells on the outer side. The large cells are formed when conditions are favorable to rapid growth, and the smaller cells when condi- tions are less favorable (Figure 294). A dry season may check growth during the middle of the summer so that an indistinct rinsr will occur between two distinct ones. This makes it impossible to tell accurately the age of a tree by counting the rings. Every part of the woody stem has a distinct use. The bark protects the tender growing parts within. The xylem carries water containing food materials from the roots to the leaves, and the phloem carries to other parts of the plant for use or for storage the food which has been made from the raw materials. As the stem increases in thickness, only the outermost layers of xylem continue to carry water, for the inner layers fill up with a sub- stance which hardens into wood. Although they are dead, these layers are still of use in giving stiffness to the tree. The work of the tree goes on without them, as is shown when a tree decays in the cen- ter. The pith in the center of a tree and in Figure 294. — Wood of Spruce. Greatly magni- fied. WiL Figure 295. Photograph of Sections of Wood. OTHER STEMS L>(.)1 the medullary rays serves as a storehouse for food and as lateral conductors of sap. Liquids are always passing along the paths indicated, but this process is observed most readily in the spring when the sap runs from the broken end of a branch. When the leaves are grown, much of the water carried to them is lost by transpira- tion, and little is left to be carried back. In the spring, water is carried down, as well as up. Most of our common lumber is made by saw- ing the trunks of trees lengthwise. Sawing in this way shows the annual rings as long lines (Figure 295), but does not show the medullary rays except in a few boards. Lumber t<> be used in furniture is often cut so as to show as many med- ullary rays as possible. The rays are lighter in color and more glistening than the woody layers. A tree grows by adding a layer of new wood each year. The branches of the current season have only a single ring of wood, while those of the season bet ore have two rings, and so on. LABORATORY STUDY OF TWIGS Examine a twig from a horse-chestnul tree, and identify 1 1 the termi- nal buds; (2) lateral buds; (8) leaf scars ; (4) dots in leaf (5) rings; ((>) scales covering buds; (7) breathing pores or lentta Dissect a bud to see what it contains. Make a cross Bection of a stem and find (1) the pith ; (2) woody rings; (3) bark in two layers. Figure 296. — Food Storage. Creeping stem of Canada ginger. 292 TYPICAL FLOWERING PLANTS Figure 297. — Celery Plant. Compare with Figures 279 and 282. Figure 299. — Twining Petiole of Clematis. Figure 298. — Cabbage Plant. Figure 300. — Twining Petiole of Nasturtium. OTHER LEAVES 293 Examine, with a microscope, a section of wood, looking for the pith, medullary rays, and annual rings. Examine the boards in the room and furniture to find the annual rings and medullary rays. REPORT OX TWIGS Record your observations in a report. 00 a - *-* O0 - 00 Q D pq < K M i. - - - — H _ SB - O - i oo - -< — ■ - - - - _ •< O W CO o £ - - . O ■A © O H z w 7. W - Y. < < c ao r" H H Z O O — 0 H 0 r. < H ■i. P i. M w 7. - 00 - H h3 : z - - - -J i - M > / _ - 6 H Z - ►3 — - :- 7 / - - - Geranium . Horse- chestnut . Lilac . . Maple . . 218. Other Leaves. — All leaves have the same work to do as the leaves of the bean, but some leaves have other Figure 301. — Barberry Leaves. Showing how a leaf may become a thorn. work in addition. The storage of food is one additional task. Celery and rhubarb (pieplant) store food in the 294 TYPICAL FLOWERING PLANTS thick, fleshy stalks of their leaves. In cabbages, the blade of the leaf is the place of storage, while in onions it is the thick enlarged base of the leaves. Clematis and nasturtiums climb by twining the petioles of their leaves around a support. Pitcher plants have leaves which hold water and entrap insects. Venus's fly- trap and sundew both use their leaves to catch insects. Plants which have leaves lasting more than one year are called evergreen; and those that shed their leaves every autumn are called deciduous (Latin, deciduus, falling off). The blade of some leaves is in one piece, as is the case with the geranium. Such leaves are called simple leaves to distinguish them from the com- pound leaves, like the rose or horse-chestnut, in which one petiole supports several leaflets. j****'^ M I ($" ■ Figure 302. — Pea Plant. Leaves modified in- to tendrils. Figure 303. — Leaf of Oak. Simple leaf. Figure 304. — Leaf of Elm. Simple deciduous leaf. LABORATORY STUDY 295 LABORATORY EXPERIMENT TO PROVE THAT LEAVES GIVE OFF WATER Wrap in waxed paper a jar containing a small plain, and cover the earth with half an inch of melted paraffine to prevent evaporation. Weigh the plant each day and note the amount of water l<»st by transpir- ation through the stomata. LABORATORY STUDY OF LEAVES Examine as many leaves as possible and record the facts which yon have learned about them in a report like the following : Leaves Simple Lb A VK8 Compound ] ) K< 1 1 1 1 • ■ 1 - Stoeaoi < LIMBING Cherry . Maple Lilac . . Ash . . Rose . Horse- chestnut . Etc. . 219. Comparison of a Monocotyledonous with a Dicotyledonous Plant. — Monocotyledon Dl< OTV LEDOM Corn r.KAN Epidermis. Same structure. Cortex. Root. Endoderm. Central cylinder. Root caps. .Root hairs. Hard outside. Thin epidermis in young plants. bark in <>M. Much pith. Pith confined to center and med- ullary rays. Stem. Scattered vascular bundles, no cam- Vascular bundles form rinp, phloem out. xylctn in. cam- bium. bium between. Vascular bundles Vascular bundles pass to uiven off from branches and to leave 3. 1 nodes, to leaves • 296 TYPICAL FLOWERING PLANTS Monocotyledon Corn ' Long, simple, and nar- row. Leaves. < No petiole, but clasp- ing base. Parallel veins. Dicotyledon Bean Broad, compound. Petiole. Netted veins. 220. The Bean Flower. — Just before the bean plant reaches full size, greenish buds appear in clusters on the ends of the branches. These green buds grow into the bean flower. This flower is made up of a number of parts, all of which have an important work to do in producing the bean seed. The parts of the bean flower have technical names which it is necessary to learn in order thoroughly to understand flowers. The green, outermost part, called the calyx (Greek, kalyx, cover), is made up of separate sepals (Latin, separ, separate) which form a cup in which the rest of the flower is fastened. The calyx protects the delicate parts of a flower while they are small. Within the calyx is the white and much larger part called the corolla- (Latin, corolla, crown). The corolla (Figures 305 and 307) is made up of irregular shaped struc- tures called petals (Greek, petalon, leaf) ; within the corolla there is a group of stamens (Latin, sto, stand) which are recognized easily by their slender stalks, filaments, and enlarged tips or anthers. At the exact center of the bean Figure 305. — Diagram of Bean Flower. THE BEAN FLOWER 297 flower and within the group of stamens is the pistil. Tin- stamens and pistil are the important parts <»l' the bean flower because they produce the bean seed (Figures 306 and 307). The stamen bears in the enlarged tip many minute bodies which are known as pollen or pollen grains (Latin, pollen, fine flour). The pistil is divided into three parts: (1) a slightly ex- panded and sticky tip, the stigma (Greek, stigma, point); (2) a slender portion con- necting the stigma with the much larger base, the style (Greek, stylos, pillar) ; (3) and the swol- len base, the ovary (Latin, ovum, egg~). See Figure 306. The ovary contains small, rounded bodies called ovules which ripen into seeds. The bean flower is a complete flower, be- cause it has all of these parts: calyx, corolla, stamens, and pistil. It is also said to be perfect because it contains in the same flower the two organs needed to produce seeds, the pistil and stamens. The word pollination is used to describe the carrying of the pollen from the anther of the stamen to the stigma of the pistil. This may be done by the wind, by insects, or by the contact of a stamen with a stigma. The bean flower secretes a sweet fluid, nectar, at its base, which is the fluid the bees gather to make in t « » honey. When a bee alights on a bean flower, it pushes its head among the inner parts to get the nectar. In withdrawing its head, pollen is brushed off and the hairy body of the bee, especially the head, is covered with it. When the bee puts its head into the nexi bean flower, some of this pollen is caught by the sticky stigma past which the bee has to push to get the nectar. Thus the Figure 306. — Diagram of Stamen (above) and Pistil (be- low). 298 TYPICAL FLOWERING PLANTS stigma is covered 01 pollinated with pollen from the stamens of another flower, and the first step is taken which results in the formation of a bean. 221. The Corn Flower. — The flower of the corn is imperfect, for it lacks one of the two parts necessary to make a seed. Both parts, however, are found on the same plant, the stamens in the " tassel " (Figure 270) at the top of the stalk, and the pistils on the " ear " (Figure 310) at the side Figure 307. — Sweet Pea Flower. Figure 308. — Fly Pollinating Wild Carrot. FERTILIZATION 2\)W Figure 309. — Swallow-tail Butterfly Pollinating Persian Lilacs. of the stalk. The style of each pistil protrudes from the ear of corn as a long green thread, called the silk. The pollen is light and abun- dant, and falls from the stamen with every stir caused by the wind. The stigma at the end of the style is sticky, as in the bean. In a field of corn where many plants are shed- ding pollen at the same time, it is almost certain that every pistil will receive at least one grain of pollen. It is to secure thorough pollination that corn is planted in fields, with the plants close together. Plants which have both sta- mens and pistils on them, but on different flowers, are called monoecious (mo'ne'shfis : Greek, monos, one ; oikus, house). Plants which have only staminate or only pistillate flowers are calif 1 dioecious (di-e'shus: *//. twoj oikus). 222. Fertilization. — The second step in the production of a ^'kh\ is fertilization. By this we mean the union of the sperm DUCleUfi of the pollen cell ( male parent ) with that of the egg cell in the ovule (female parent ). The pollen grain has two coats, an outer ami an inner. The outer is thicker than the inner, but it has thin spots Figure 310. — Corn Flower with Pistils. 300 TYPICAL FLOWERING PLANTS in it. When a pollen grain falls on a sticky stigma, the inner coat pushes out through one of the thin places, forming a tube into which all the contents of the pollen grain flow. The contents, at this time, consist of two nuclei and a small amount of protoplasm. The pollen tube grows and pushes its way through the loose tissue of the stigma till it reaches the ovary containing the ovules (Figure 311, a, 6). The ovules are attached to the sides of the ovary. Each has a Figure 311. — a, pollen grains growing through pistil ; b, same magnified ; c, nuclei of pollen and egg. thick coat called the integument which does not quite meet at one spot, known as the micropyle. Inside the ovule is the embryo sac containing the egg cell and a few other cells. When the pollen tube reaches the micropyle of an ovule it enters, touches the egg cell, and bursts. The male nucleus unites with the nucleus of the egg, and fer- tilization is accomplished (Figure 311, c). The other nu- cleus of the pollen tube usually unites with a nucleus near the center of the embryo sac and helps to form tissue which may be of use to the growing embryo or may form a part of the mature seed. The fertilized egg cell soon begins to divide and grow, and OTHER FLOWERS :-;i ) l finally it develops into the embryo, consisting of plumule, hvpocotyl, root, and cotyledons. The integument changes to testa, food is stored up for the embryo, and the seed is ripe, ready to start a new ijlant, although it may have to wait for vears before conditions allow it to sprout. 223. Other Flowers.— Flowers like the bean which have all the parts usually found in a flower — sepals, Figure 312. — Pistillate and Stami- nate Flowers of Willow. 0& Figure 313. — Violet. a, cleistogamous flowers. 302 TYPICAL FLOWERING PLANTS petals, stamens, and pistil — are complete. As we have seen, they are also perfect because they have in the same flower stamens and pistil, the parts necessary for the production of seed. An imperfect flower may be staminate, having only stamens, like the tassel of the corn, or pistillate, hav- ing only pistils, like the ear of the corn (Figure 312). So an incomplete flower may lack either sepals or, as is more common, petals. Hepatica is an example of a flower which lias no petals, but its sepals are colored. Regular flowers are those in which all the parts of the same kind are the same size and shape, as in the blossom of the apple. In irregular flowers all the petals or sepals are not of the same shape. The bean is an irregular flower, and so is the violet. Cleistogamous flowers (klis-tog'a-mus : Greek, klistos, closed ; gamos, marriage) are found in the violet (Figure 313) and pansy in addition to the flowers of the ordinary type. These are formed underground near the surface, have no colored parts, usually only one stamen, and they never open. They produce many seeds, however. FIELD AND LABORATORY STUDY Study flowers in field and laboratory, and record the results, using the following table as guide. Geranium . Castor bean Salvia . . Nasturtium Pansy . Etc. . . O 1= o K — — - - Corolla Lacking Stamens only in a Flower Pistils only IN a Flower X X X c ~ ■J w Carolus Linnaeus (ihe Latinized form of the name Karl von Linne) was born in 1707 and died in 1778. He was a celebrated Swedish botanist and naturalist. Linnaeus went to the University of Upsala in 1728, attracted by the fame of Rudbeck, the Professor of Botany, whose assistant he became. In 1732 he explored Lapland. Later, while studying in Holland, he wrote works on botany which attracted wide attention. In 1741 he became Professor of Botany at Upsala, whither his fame attracted students from many foreign countries. Linnaeus' sys- tem of plant classification greatly promoted the study of botany in his day. OTHER FLOWERS 303 Figure 314. — Two-parted Flower of Mint. Note the convenient place for the bee to alight ; b, stamens in usual position ; c, stamens bent down by bees. Pollen will be shaken on to the bee and carried to another flower. The classification of plants by stamens and pistils was originated by Linnaeus, the usual name given to Carl von Linne (1707-1778), the Swed- ish botanist. During the period of his studies many new plants were beinsr brought to the attention of botanists by the traders who were constantly penetrating to parts of the world hitherto but little known. In 1737 Lin- nams published his famous book, G-enera Plantarunu in which he gave special names in the nomenclature of plants, and also first enunciated the principles of defining general species and the use of specific names. For his achievements in the field of botany Linnaeus was elevated to the nobility. Flowers are also classi- fied according to their method of pollination, that is, whether by in- sects or by the wind. Insects have an objecl in visiting flowers, for in Figure 315. — Lady Slipper. them they find the Pollinated by insects. nectar which tliey make 304 TYPICAL FLOWERING PLANTS into honey, or they find pollen, which they eat and feed to their young. Insects are attracted to flowers by their strong odor or bright colors, or by both. One of the most interesting studies in biology is the relation which exists between certain flowers and the insects which pollinate them. In the case of salvia or flowering sage, for example, the ir- regular corolla offers the bee a con- venient place to alight. To suck up the nectar the bee must push its head into the cup of the flower where it is forced to brush against the stigma which becomes covered with the pollen from the last salvia flower which the bee visited. When the bee withdraws its head it becomes dusted with pollen from the anthers which bend down and touch the back of the insect. The stamens and pistil of salvia do not mature at the same time (Figure 317), so that the bee can carry pollen only from flowers in which the stamens are ripe ; and the pistil will receive pollen only in the flowers that have a ripe pistil. Certain orchids have deep tubes from which the nectar can be drawn only by insects like large moths which have long sucking organs. Many orchids have their pollen in masses. These masses stick to the head of the insect visitor, and hang down while it is passing to another flower. In this position the mass is almost certain to be rubbed off on the stigma of the second flower. Red clover is dependent on bumble bees for pollination, for they Figure 316. — Flower of Columbine. Showing spurred petals. Only a long- tongued insect can reach the nectar. Note the bunch of stamens upon which the insect alights. POLLINATION :m have a tongue of the length to get the nectar. The pollen is carried as in the case of the bean. Flowers which are pollinated by wind have no need of color or of odor, but they have pollen which is Light, abundant (for much of it is lost), and easily shed from the anthers. The stigma is feathery, thus offering more surface for the grains of pollen. Grass and corn, as we have seen, are examples of flowers pollinated by the wind. It is an advantage in securing proper pollination for such plants to grow close together. LABORATORY STUDY Pollination of Flowers. — As soon as flowers come, observe them closely and note which have many insect visitors, and which few or Done. Fill out a report as suggested below and add any points which int< you further. 1 E- fc> V. XI o H < L- t> C5 * n O fa an Z, O O es o ao O o o a S5 O PS H « 55 O M H n O 3 n Z si < V. - H O > < 00 : - 00 00 - - H oo R - - o ►4 OS Q O o < — o o 0 z C £ H Sweet pea . Dandelion . Hepatica Buttercup . 224. Cross- and Self-Pollination. — All plants which re- ceive pollen from another plant of the same kind arc said to be cross-pollinated. Darwin found that {»lants which grow from seeds resulting from cross-pollination produce a greater number of seeds and that these seeds have more vigorous embryos than those resulting from self-pollina- 306 TYPICAL FLOWERING PLANTS tion. Since this has been known, nursery men and gar- deners have taken advantage of cross-pollination to improve their stock and to produce new varieties of fruits and vegetables. Much of Luther Burbank's wrork has been based on cross-pollination. Plants have a num- ber of devices for pre- venting self-pollina- tion. The anthers, for instance, may be turned away from the stigma ; or the pistil may be so tall that no pollen can get on it from the stamens of the same flower; or the stigma may be ripe and the ovules started to develop before the stamens of the flower are ready to shed their pollen (Figure 317). While it is the rule that plants avoid self-pollination and self-fertilization, a few have no other way of producing Figure 31 7. — Salvia. A flower in which the stamens mature at one time and the pistils at another. Figure 318. — Easter Lily. seeds. This is true of cleistoofamous flowers. The one or two stamens which they develop contain sufficient POLLINATION 307 pollen to fertilize all their ovules, for none is lost, and the pistil and stamen are placed in such a position that pollination is sure to occur. Other plants, as some of the lilies, are ar- ranged for cross-ferti- lization, but if that fails, they can pollinate them- selves. An Easter lily at first keeps its three- parted stigma carefully closed until it is well out of the way of the anthers (Figure 318, a). Then the stigma opens out, exposing its sticky surfaces to the air and to insects which may visit the flower (Figure 318, h ). If no pi 'lieu is brought to the stigma, however, the plant brings the pistil up until the stigmas almost touch some of its own anthers Figure 319. — Fruit of the Bean. A pod. Figure 320. — Fruit of the Corn. Kernels or grains. 308 TYPICAL FLOWERING PLANTS dry capsule from which pollen is received for the fertilization of the lily's own egg cells in the ovules (Figure 318, c). 225. The Fruit of the Bean and Corn. — In science the term fruit includes much more than the meaning we usually give it when we refer to apples, oranges, or berries. By fruit the botanist means the ripened ovary of a plant and its contents. The first step in the production of fruit is the pollination of the stigma of a flower. Next comes the fertilization of the egg cell in the ovule. Finally the ovule develops into a seed, and at the same time, the ovary grows to protect and to pro- vide nourishment for the seed until it is mature. In the bean plant the pod begins to develop from the pistil as soon as fertilization has taken Figure 321. — Fruit of the Poppy. A capsule. sepals Figure 322. — Capsule of Violet. Figure 323. — Chestnuts. A dry fruit. OTHER FRUITS 309 place. Each ovule remains attached to the pod until the former changes into a seed and becomes mat inc. In bean pods and string beans, ovules are often present which have not developed owing to a lack of ferti- lization of the egg cell. When a bean pod is ripe, it splits and sometimes curls up, thus helping to scatter the seeds. From seed to seed again makes up the life his- tory of the plant. In the corn, as in the bean, each ovule develops into a grain of corn, if the egg cell has been fertilized. The ovary ad- heres so closely to the egg cell that it cannot be seen as a separate organ like the pod of the bean. All the maturing grains of corn receive nourishment through the cob to which they remain attached, and they are pro- tected by the modified leaves or husks. Undeveloped ovules are sometimes found in ears of corn. ^vA /A l>'\ - • Figure 324. — Dry Fruits. a, beechnuts ; b, acorn. Figure 325. — Vertical Section of Apple. A pome. Figure 326.- Cross Section of Apple. A pome. 226. Other Fruits. — The ripened ovary and its contents take many forms, so that we have the fleshy fruits, such 310 TYPICAL FLOWERING PLANTS Figure 327. ■ Cross Section of Orange. A berry. as the apple, or dry fruits, like the bean. Pods and other fruits which open in a definite way are called dehiscent (Latin, dehisco, to split open) fruits. Poppies, pansies, and violets have dehiscent fruits called capsules. Nuts, corn, and wheat are examples of indehiscent fruits (Fig- ures 323 and 324). Fleshy fruits fall into three groups : (1) pome fruits, apples and pears which have the seeds in a core in the middle surrounded by a thick, fleshy part (Figure 325); (2) drupes, or stone fruits represented by the plum, which has the seed inclosed in a hard stone surrounded by soft pulp; and (3) berries, fruits in which the seeds are scat- tered through the pulp, as in the grape, currant, or orange (Figure 327). Most of the fruits commonly called berries are really collections of small drupes. In the strawberry each " seed " is a fruit, and the fleshy substance is the receptacle of the flower, which has been greatly enlarged. In the case of the blackberry, as well, the receptacle is eaten, for the drupes cling- to it as it is removed from & Figure 328. — Forms of Dehis- the bush. Melons, cucumbers, cent Fruits. SEED DISTRllirTlOX :m Figure 329. — Fruits with Hooks. Distributed by animals. pumpkins, and squashes are a special kind of berry called pepo. Such fruits have a hard rind. The use of fruits to plants is simply to pro- tect the seeds while they are maturing, and to secure their distribution later. But the fruits of the cereal grains and of beans furnish the highest form of vegetable food for man and domestic animals. The fleshy fruits, on the other hand, furnish many of man's luxuries in the way of food. One of the most interesting studies about plants is how their fruits may be improved by supplying the best possi- ble conditions for their growth; how their flavor may be improved, the skins made thicker or thinner, t lie seeds grown larger or smaller, or such other chang made as to cause the fruits to be more de- sirable to man. Many of these changes may be brought about through cross-fertilization. 227. Seed Distribution. — Seeds must be scat- tered or distributed to " spread " the plant, and the fruit helps to do this. It' all the seeds merely fell to the ground Figure 330.— Burdock in Blossom. and germinated there, 312 TYPICAL FLOWERING PLANTS Figure 331. — Fruits Distributed by Wind. but little range would be added to the plant's territory, and a small increase in the number of plants would take place. Such plants as the dandelion and bur- dock have developed the most successful means for gaining the distri- bution of seed, and are, therefore, the most common and most widely distributed. Seeds may be distributed by an explosion of the fruit case or through the agency of the wind, water, or animals. Some plants, like the witch- hazel or jewel- weed, have a fruit the tissue of which is so strained at the time of ripening that the seed case bursts with an explo- sion which throws the seeds some distance from the parent plant. Figure 332. — Other Fruits Distributed by Wind. a, catalpa ; b, dandelion ; c, milkweed. Figure 333. — Fruits and Seeds. SEED DISTRIBUTIOX 313 Frequently plants de- velop special structures which help to secure the distribution of seeds through the agency of an animal. Fruits like the burdock, for ex- ample, are provided with hooks which catch firmly to a passing animal, and the fruit is carried lomr distances before the seeds are dropped. Other fruits, like the cherry, have an edible pulp which causes the fruit to be picked up and carried away. A bird may fly with the fruit to a fence post, and there eat the pulp and drop the seed. In many cases, as in the raspberry, the whole fruit is eaten, but the seeds are indigestible and are carried far from the parent plant before they are thrown out by the animal. Other fruits are fitted for distribution by water. In such cases the fruit is surrounded Figure 334. — Milkweed Plant. Distributing seeds. Figure 335. — Seed of Cotton. 314 TYPICAL FLOWERING PLANTS by a light, buoyant substance, as in the bur reed and the cocoanut, and so may be carried hundreds of miles without injury. In the case of still other fruits, like grains, the whole fruit is eaten, but enough are produced by the plant so that many may be destroyed and yet some be left to serve as seed, and thus prevent the plant from becoming extinct. Squirrels, in storing up food for the winter often bury nuts which are not used, and some of these are sure to grow. LABORATORY STUDY OF SEED DISPERSAL Every season of the year affords material for this phase of plant study. Record your result as follows : Agencies Devices r. a> -d 3 "ci "35 CO M 3 .£ O 6 £ c3 < o y, r-r! P n c -3 ^ Dandelion . . . Maple .... Burdock . . Cherry .... Etc 228. The Struggle for Existence. — In the process of dis- tribution, six or eight seeds from a plant may fall in al- most exactly the same place. It is probable that all will begin to grow, but only one or two will live, because there will not be sufficient light, food, or moisture for all. In this case the plants which get the best start or have the most vigor crowd out the others. In biology this effort to secure the conditions necessary for life is known as the struggle for existence. The result of this struggle is spoken of as the survival of the fittest. ENEMIES OF THE BEAN 3 1 5 Figure 336. — Bean Plant Injured by Bacteria. 229. Enemies of the Bean. — Besides this struggle to gel its share of light, food, and moisture, the bean plant has to contend with enemies. One enemy is a plant or bacterium (Chapter XXI II) which lives upon the tissues of the bean. This bacterium causes the dis- ease known as bean blight, one of the most destructive diseases of beans, and one which scientists have been unable to prevent or cure. The plants having bean blight appear wilted, and have clear watery spots in the leaves which, after a time, turn brown, dry up, and drop out, leaving a hole in the leaf where each spot was. The bacteria which cause the disease enter through the stomata, appear first in the cotyledons, then work into the stem, and finally kill the plant by stopping up the sap tubes. The bacteria arc carried by insects from one plant to another. Any insect which carries these bacteria is indirectly an enemy of the bean plant, hut bean weevils injure it directly ( Figure 337 >. The female weevil gnaws holes through the young pod and pushes her eggs into the pod or into the young beans. The eggs develop Figure 337. — Beans Damaged by Weevils. 316 TYPICAL FLOWERING PLANTS into grubs or larvae, which get their food from the sub- stances of the bean seed. If the grubs mature, the weevils may craAvl out, thus leaving large holes in the bean. The loss to the farmer comes not only in the food actually eaten by the weevils, but also in spoiling the beans as food for man. If the pods show that the beans have been pierced by weevils, the development of the eggs can be prevented by storing the beans in a cold place. A test for the presence of weevils is to place the beans in water, where those that contain Aveevils will float. 230. Enemies of Corn. — One great enemy of corn is a fungus (see page 360) called corn smut. This fungus destroys the corn kernels by living on the food in them and filling the whole kernel with black, sticky spores. Grasshoppers injure the corn plant by eating the leaves, and plant lice by sucking its juices. In speaking of an animal as a friend or an enemy of a plant or of man, we should remember that every plant and animal is only endeavoring to maintain its own life. We regard them as enemies when they destroy or injure some- thing which we are trying to raise to maintain our own lives, and as friends when they destroy our enemies. 231. The Raising of Beans. — Beans are raised in large quantities for food. In New York, Michigan, and California more than nine million bushels were raised in the year 1915. Michigan raised four and a quarter million bushels, and New York one and a quarter million bushels. A crop of beans can be planted, cultivated, harvested, and threshed by tools and machinery. But before beans can be used as food they must be examined by some one so that all those discolored or specked by weevils may be discarded. Beans unfit for human food can be eaten by such animals as hogs and sheep. So we find that where HISTORY OF BEAN PLANT 'Ml the raising of beans is an important industry, the raising of hogs and sheep is also practiced extensively. Sheep eal not only the rejected dry beans, but also the pods. Certain varieties of beans are eaten when young and « I green, the pod itself being used as an article of food. Figure 338. — A Field of Beans. These "string beans" are raised extensively in some localities and are canned for the market. In this industry much of the work has to be done by hand. 232. The Value of Beans as Food. — Beans furnish more protein and yield more energy than any other kind of plant food except wheat. Compared with the cost of meal or of eggs, vegetable forms of protein are much cheaper, and beans are the cheapest of all. String beans do not contain so much nourishment as dry beans. Beans properly cooked are both digestible and palatable and should form an even more important part of our diet than at present. 233. History of the Bean Plant. — The bean and the mem- bers of the bean family (beans, peas, clover) are known to have been cultivated from the earliest times .>!' human history. They are spoken of in the Bible under the name of pulse (Daniel i. 12), and mention is made of them in the records of the Kgyptians, (i reeks, and Roman8. When America was discovered, the Indians were cultivating pole 318 TYPICAL FLOWERING PLANTS beans. Beans are now widely distributed, one or more varieties being grown in all temperate regions. The value to the soil of the plants of the Pulse family has long been known, bat the reasons for it have not been understood until recently. As we have seen, bacteria in the roots of beans gather nitrogen which goes to replace that drawn from the soil by other plants. Soils which lack nitrogen may be improved by growing on them a crop of the pulse family and then plowing it under. This method of enrich- ing the soil is known as " green manuring." See page 270. The bean family in- cludes such well-known plants as peas, peanuts, clover, and alfalfa. The peanut has the peculiar habit of thrusting its blossoms into the ground after they have been polli- nated. The pods mature there and are harvested by digging. 234. The Raising of Corn. — Most of the work of planting, cultivating, and harvesting corn is done by machinery. Hand work is necessary only in removing the ears from the stalk and the husk from the ears. Because corn is so valuable a food for men and animals and because so much of the work necessary in raising it can be done by machin- ery, corn raising has become one of the most important industries on the easily cultivated level prairies of the Middle West. Figure 339. — Peanuts. THE RAISING OF CORN 319 z c p o D Q O a. Qu 2 O O u. o a. < 5 CO D O 320 TYPICAL FLOWERING PLANTS 235. History of the Corn Plant. — The corn plant was found growing in America when the New World was discovered, and it was one of the principal foods of the Indians. Now corn is grown wherever the climate is not too cold for it to come to maturity. 236. Economic Importance of Plants. — From a biological point of view much of the study of plants is concerned with the life of the plant itself, considered as an organism; what its problems are, and what peculiarities it has devel- oped which have aided it in the struggle for existence. There is, however, another point of view, — the importance of plants to man as the source of his food supply. Within recent years, this has come to be more fully recognized than ever before, and as a result, agriculture as an industry has been almost revolutionized by the application of scien- tific methods. Man has learned to take a wild plant and, by cultivation, selection, and cross-pollination, to improve any part of the plant he wishes. Man is the only animal intelligent enough to do this, and his success depends upon his following such natural laws as he has been able to discover. Students are constantly endeavoring to learn the conditions under which each plant thrives best, — the kind of food, soil- temperature, amount and kind of cultivation; what dis- eases it is likely to have, and how to prevent and cure them. SUMMARY OF THE BEAN The bean is a typical flowering plant and is represent- ative of the dicotyledons. The bean seed contains an embryo which is nourished by the food in the cotyledons. A bean plant has roots to hold it firmly in place and to gather the water which contains part of the plant's food. It has a stem to hold the leaves to the light and air, and SUMMARY OF CORN 321 to carry water and food. The Leaves are the pari of the plant where most of the vital processes are carried on. The vital processes which occur in the leaf are respiration, photo-synthesis, or the making of food, excretion, and assimilation. The bean flower contains the organs necessary for re- production. A seed is formed when the nucleus of a pollen grain unites with the nucleus of the egg eel] in tin- ovule. The fruit of the bean is the pod which contains the seeds. The bean depends upon insects for cross- pollination. The raising of beans is an important industry. Beans probably once grew wild, but now they are widely culti- vated. Their chief value as food is due to the large amount of protein in the seed. A bean plant which has successfully completed its life work has added to the sum total of the solid matter on earth, and has left stored-up material which may be used either as food for animals or for the new plant which the seed contains. The plant has added to the supply of oxygen in the air, and by decomposition through the aid of bacteria leaves the soil richer in nitrogen. SUMMARY OF THE CORN The corn is a typical monocotyledonons plant. Food for the embryo is stored at one side of the grain. This embryo is supplied with food prepared in a modified cotyledon. A corn plant has many roots, all of about the same size. which srather for it water and inorganic matter and hold the plant in the soil. In addition to the regular loots, there are prop-roots. The leaves of coin have parallel veins and clasping bases. The leaves perform most of the vital processes of the plant. The stem has a hard rind and 322 TYPICAL FLOWERING PLANTS scattered fibro-vascular bundles. The fruit consists of grains in which the ovary adheres closely to the seed. Corn depends upon the wind for pollination. The stamens are in the tassels and the style of the pistil is the silk. It is a monoecious plant. QUESTIONS How does the bean plant begin life ? Explain the work of each part of the plant. What is the importance of photo-synthesis ? What is the dif- ference between pollination and fertilization ? Why are beans valuable ? What is a food ? How can you show that any given substance is a food ? How do roots help the leaves ? How do the stems help the leaves ? Compare the corn plant with the bean in structure, importance, etc. REFERENCES Campbell, University Textbook of Botany, p. 9. Coulter, Barnes and Cowles, Vol. I, pp. 363-380. Kellogg, The Animals and Man, Chapter 15. Leavitt, Outlines of Botany. Roots, pp. 26-44. MacDougal, Enzymes, pp. 173, 265, 274. Needham, General Biology, pp. 7-33. Sedgwick and Wilson, Biology, Chapter I. U. S. Department of Agriculture Bulletins. Coulter, Plant Life and Plant Uses, Chapters 1, 2, 4, 5, 6, 7, 8. CHAPTER XX r OTHER FLOWERING PLANTS 237. The Flowering Plants. — True flowering plants are the most highly developed of all. They arc numerous, it being estimated that there are 120,000 kinds. Some varieties are so small as hardly to be noticed, while others, like the hardwood trees, are very large. Some live submerged in the water, while others are found only in deserts. The flowering plants are of special interest on account of their in- timate relation to our daily life, and on account of this close relationship we should study some of the most common Figure 341. — Walnut Tree. families, such as the grass, rose, mustard, and the like, all of which are easily recognized. The Grans Family. — The grass family has long narrow leaves with clasping bases and parallel veins, fibrous roots, and inconspicuous flowers which are pollinated by the wind. The grasses arc the most important of all 323 324 OTHER FLOWERING PLANTS (A H < o u. o O H O Q O cu It o < ON CO U a: o OTHER FLOW K RISC PLANTS 325 2 O H O D Q O a, 2 r u. o a. < a 326 OTHER FLOWERING PLANTS Figure 344. — The Cereals. a, wheat; b, oats; c, barley; d, rye. plants as food for man and the animals which he uses. This family includes corn, wheat, oats, barley, rye, rice, and similar grains. Wheat and barley are mentioned in the earliest literature and were among the first plants cultivated for food. As men learned to till the soil and harvest these grains, agriculture became estab- lished and a marked step towards civili- zation was made. In China and India millions to-day depend very largely upon rice. In 1915 the United States pro- duced 3,054,535,000 bushels of corn, 1,011,505,000 bushels of wheat, and 28,974,000 bushels of rice. Lily Family. — Lilies have parallel- veined leaves. The flowers are made Figure 345 -Lily- uP °^ a six-parted perianth (calyx and of-the-Valley. corolla taken together), six stamens, and THE CROWFOOT FAMILY 327 Figure 346. — X-ray of Easter Lily. a three-parted pistil. The fruit is a capsule. Lilies are cultivated chiefly for decorative purposes. Wt this family arc hydrast is, aconite, hellebore, and Larkspur ; while other members, as clematis, peony, and columbine, arc cultivated for orna- ment. The common Figure 347. — Leaves and Bud of Beech, buttercup shows most 328 OTHER FLOWERING PLANTS Figure 348. — Wild Columbine. Figure 349. — Stamens and Pistils of Rose. of the characteristics of the crowfoot family. The leaves are commonly dissected ; the petals, sepals, and pistil are all disconnected. The juice of the buttercup is color- less and is biting to the taste. Mustard Family. — Garden vegetables such as the turnip, radish, cabbage, horse-radish, and mustard belong to this family. All have regular flowers consist- ing of four sepals, four petals, and six stamens. The corolla is in the form of a Greek cross. These plants have a pungent, watery juice which is non-poisonous. The fruit is a kind of pod called a silique. Rose Family. — The flowers are regular with the calyx usually of five sepals and the corolla of five petals. The leaves are alternate and usually serrate on the edge. The rose family is as important in furnishing the luxuries of our food as the grass family is for the necessaries. To THE PARSLEY FAMILY 329 this group belong all of the common orchard fruits, such as apples, peaches, and plums, and many of the common berries, such as the raspberry and strawberry. Many of the members of this family are also cultivated for ornament. Pulse Family. — Beans, peas, vetch, alfalfa, peanuts, clover, and the like are members of this family. These plants may be recognized by their irregular, papiliona- ceous flowers, alternate leaves with stipules, and by their having the fruit in the form of a pod. This family furnishes us with most of our vesre- table protein food. The plants improve the soil by the aid of bacteria. Figure 350. — Rose Flower Wisteria, red bud, and Turning into a Fruit. the locusts are cultivated <*> early staSe ; *>, later for ornamental purposes. Flax Family. — While this is not a large family, yet it furnishes all of our Linen. Flax rarely grows wild, but requires cultivation. Mallow Family. — This family is also impor- tant in furnishing material for cur clothing, as the cotton plant belongs here. Hollyhock and Figure 351. althsea are forms cultivated for ornament. of Rose/ Parsley Family. — This family includes such garden vegetables as parsnip, parsley, and carrots, and plants like fennel, dill, coriander, and caraway used for medicine and for flavoring food. These plants **i ^ 330 OTHER FLOWERING PLANTS THE NIGHTSHADE JAMIL) 331 have hollow, ribbed stems; alternate, compound leav< . and flowers in an umbel. See Figure 308. Figure 353. — Stipules of Rose Leaf. Figure 354. — Flower of Mallow. Mint Family. — The members of this family are easily recognized by their square stems, opposite leaves with crenate margins, and bila- biate flowers (an irregu- lar flower divided into two parts). Peppermint, spearmint, catnip, hore- hound, pennyroyal, sage, savory, and thyme are some of the mints used for medicine and in food. Nightshade family. — Here are found many poisonous plants, as to- bacco and Jimson weed from which stramonium (similar to belladonna but more powerful) is obtained. The tomato, potato, and egg-plant are used for food. Petunias are cultivated Figuke 355.- Water Huklh.und. 332 OTHER FLOWERING PLANTS 2 O o D O Ou 2 O H O O u. o < CO UJ o 6 £ H THE NIGHTSHADE FAMILY 333 Figure 357. — Self-heal A common weed. 5 .. A ' 5* 7» \V ' - . f* HA i . •* MSfn^ • x Figure 358, — Hedge Nettle. 334 OTHER FLOWERING PLANTS Figure 359. — Common White Daisy. for ornament. The foliage of all these plants is rank- scented, the leaves are alternate, and the flower five- parted. The Composite Family. — This family is typified by the common daisy and dandelion. They have their flowers in heads and are of two kinds, ray-flowers and disk-flowers. This is one of the largest families of plants, and from the standpoint of the botanist, the most complex. It contains our common weeds, such as the daisy, dandelion, golden rod, aster, bur- dock, thistle, and hawk- weed. Not all the flowering \y 1 Figure 360. — Dandelion. THE COMPOSITE FAMILY 335 336 OTHER FLOWERING PLANTS plants are beneficial to man, and every farmer and gardener has to struggle with the weeds.1 Some of the members of the composite family, like the goldenrod and daisy, lend a charm to the fields, and many people dislike to think of them as obnoxious plants. But they pre- vent the grass from growing, and cattle will not eat them either in the winter or in the summer, so that they are a nuisance to the farmer. A weed, then, may be defined as a plant which interferes with the growth of some useful plant. Weeds are suc- Figure 362. — Canada Thistle. cessful in growing and in living, because they have strong roots, produce many seeds, and have numer- ous devices for distributing their seeds. SUMMARY The flowering plants are the most highly developed of all the plants and bear an intimate relation to mankind. The many grasses and cereals furnish, animals and man with much of their food. The cultivation of these plants has aided the development of civilization. 1 Thompson, "Distribution of Weeds by Means of Farm Seeds." School Science and Mathematics, December, 1915, page 770. Georgia, A Book of Weeds- Ql'KSTlOXS 33' QUESTIONS What plants furnished part of your f<>« >< J t < »-f which are used in medicine. What plants are u- 'I in making paper? What parts of a plant are used in making hous* What kinds of cloth are made from cotton? from linen? from .-ilk? from wool ? What are the common weeds ? CHAPTER XXII THE SIMPLEST PLANTS 238. Introduction. — Many plants when full grown never have mere than one cell and are so small that they can be studied only through a microscope. All of these minute plants have long scientific names, often hard to remember, but they are the same names which the English, German, or Japanese children have to learn when they study these plants. The two plants discussed in this chapter belong to the group known as the Green Alyce (Latin, algce, seaweed). The names of these two plants are Pleurococcus (plu-ro-kok'iis) and Spirogyra (spi-ro-ji'ra). We are now to compare these microscopic plants with the bean plant with its many parts com- posed of hundreds of cells, which is able to respire, make its own food, and grow bean seeds. 239. Pleurococcus. — Pleurococ- cus is a widely distributed, single- celled plant which grows in great abundance upon the shady side of trees, old buildings, and rocks. After a rain it is conspicuous in these places as green patches. A bit of this green substance examined with a microscope shows many green cells. Each plant, or we may say, each cell is a somewhat roundish structure 338 Figure 363. — Pleurococcus. a, single cell; b, cell dividing; c and d, groups of cells. SPIROGYRA 339 with a clearly defined cell wall. The contents <>f the cell are green, due to the chlorophyll which conceals all parts «»t' the cell except the nucleus. Tin; nucleus usually li«-^ uear the center of the cell. As lun«r as the cell is full of chlo- rophyll, the cytoplasm cannot be Been ( Figure 363). Pleurococcus makes its own food as tic bean does, ami apparently it is able to digest the starch and protein which it makes in a manner similar to that of the bean. When- ever a number of pleurococcus cells are examined, some are found to be dividing. In this division the nucleus forms two nuclei which move apart. A partition wall forms and two cells take the place of the old or parent cell. This method is called fission (Latin, Jixsn*\ cleft ), and is the simplest form of reproduction. In pleurococcus the cells do not always separate at once, but form groups of two, three, or four cells (Figure 363). SUMMARY This simple unicellular (one-celled) green plant, pleu- rococcus, lives and makes its own food and grows new cells. While there are no flowers and seeds as in tie- bean, yet this plant is able to reproduce itself. All of the important life processes found in the bean take place in the simple, single cell. LABORATORY STUDY OF PLEUROCOCCUS Study this as an example of a plant which consists of a Bingle cell, but still performs all the processes common t.> higher plants. Soak :i bit of bark and scrape it ucntly to ^et the pleurococci cells, some ot which may be in groups. Draw a single cell ami a group of .ells. 240. Spirogyra. — This plant is best known as the "pond scum " which l;to\vs in most fresh water ponds and in slow running streams. It may be kepi for some time in glass dishes in a laboratory. Instead of being made up of 340 THE SIMPLEST PLANTS single cells or clusters of cells, the cells of spirogyra are cylindrical in shape and are attached end to end. This results in long, fine threads which float in the water in large masses. The individual cells of spirogyra are provided with one or more narrow green bands arranged spirally within the t" — r""1-?^ |fT;-;T)^^»J•r near the center 01 the cell. (This can be seen clearly by patting a drop of weak iodine under the cover glass, using fresh material for this test.) (4) A spiral band of green coloring matter, chlorophyll, containing bright spots. Examine spirogyra in a mass, floated out in water in a ulass oron ;■ plate. Feel of it and observe that it is slimy. Note its color and delicai After it has been in the sun for a lime, note the bubbles of gas entangled in the spirogyra. which help to make it float With a microscope • amine filaments which are joined in places by outgrowths from othei filaments. Such filaments are said to be in conjugation. Draw the out growing tubes, the emptj cell, ami the zygospore or zygote. 342 THE SIMPLEST PLANTS SUMMARY Both pleurococcus and spirogyra are called algae, and each is typical of many other plants of the same kind. Our chief interests in them are that they are adapted to life in the water from which they obtain most of their food and that each cell is capable of carrying on all the life processes for itself. Plants like pleurococcus are called unicellular ; those like spirogyra, which consist of many cells joined end to end thus forming a strand, are called filamentous algce. Pleurococcus is found on old buildings, fences, posts, rocks, and on the bark of trees. It shows more plainly in wet weather than in dry, for then it is growing. Spirogyra grows in running water, attached to objects on the bottom, or floats in masses on the surface of ponds, ditches, and sluggish streams. Neither of these plants has any economic value. Algae are simple plants which grow in water or in moist places. Fresh water algae are usually small. Algae illus- trate how a plant cell carries on the life processes. The cell is the unit of plant structure, and plant cells are similar to animal cells in all essential respects. QUESTIONS What is a cell? Compare plant with animal cells. Explain the process of conjugation. In what respects is the formation of a zygospore similar to the process of fertilization in the bean ? REFERENCES Atkinson, High School Botany. Bennett and Murray, Cryptogamic Botany. Bergen and Caldwell, Botany. Leavitt, Outlines of Botany. CHAPTER XXIII THE SMALLEST PLANTS (BAOTEEIA) 241. Bacteria. — Bacteria are the smallest of all plants and can be seen singly only through the aid of a powerful microscope. We do not know all about their life pro- cesses, but we have learned much about their effect. We constantly hear about these plants, cither under their correct name, bacteria, or under the names of germs <>r microbes. Two incorrect ideas concern- ing bacteria are prevalent, — one, that bacteria are animals, and the other, that all of them are harmful. It is definitely known that bacteria are plants ; that small as they are, they are among the most important plants in the world ; that most of them are helpful, and only a FlG few harmful. They are, however, so much like the one-celled animals (protozoa) that the word germ is not unnaturally used to cover both. 242. Shape and Size of Bacteria. — Bacteria, according to their shape, are grouped into three classes: (1) round (the cocci); (2) rod-shaped, like an unsharpened pencil (the bacilli); (3) those that are shaped like a corkscrew (the spirilla). Most of the names for the different bacteria contain one or another of these words, thus indicating the shape of the bacterium1 under discussion. The spirilla and the bacilli often have on one or both ends tiny thread- 1 Bacterium, singular of bacteria. 34:; 344 THE SMALLEST PLANTS (BACTERIA) like hairs by which they move, so that the first observers not unnaturally thought they were animals. An indication of the minuteness of these plants is that fifteen hundred of the rod-shaped bacteria will hardly reach across the head of a pin. When bacteria are grown in the proper kind of substance, there are so many in a cluster that they appear as tiny spots or points, often tino-ed with a faint color. When seen alone under the microscope, they are clear, almost transparent, and color- less, and often have a bright, shining spot on the inside. 243. Where Bacteria are Found. — Bacteria are everywhere, — in the air, as invisible dust ; in the upper layers of the soil ; and in water. We breathe in the microbes of the air with every breath, but generally with no injurious result. Every bacterium has its own work to _ do, and a healthy body gives Figure 368. — Soil Bacteria, little opportunity for most kinds of bacteria to do harm. 244. Conditions Necessary for the Growth of Bacteria. — Like all other plants, bacteria must have all the proper conditions before they can grow and multiply. Their food is chiefly plant or animal matter, but they cannot make use of food except in the presence of warmth and moisture, and most of them require oxygen in addition. They get the oxygen from the surrounding air. 245. Life Processes. — In the preparation of their food bacteria break up substances or decompose them, causing the condition known as decay. They use some of the material resulting from decay ; some they set free in the air ; and the remainder is left on the earth to be used by LIFE PROCESSES 345 higher plants. In changing dea full size in half an hour and be ready to divide again. It is this abilil to multiply rapidly which makes them of so great impor- tance, for a few hundred bacteria, even of the harmful ones, could produce little effect. In the process of growth, bacteria produce two sub- stances, enzyme (see page 172) and toxin (toxin: Greek, toxicum, poison). Enzymes produce fermentation, a break- ing-up process of which man makes use to secure certain flavors and odors, as well as to soften hard materials. Toxins are usually poisonous to living organisms, includ- ing the bacteria which produce them. Enzymes cause the pleasant flavor of such articles of food as cheese and butter. The quality of tobacco depends largely upon the kinds of bacteria which have been at work upon it. Such bacteria are classed as helpful, as are those which gather nitrogen for the plants of the bean family. Other helpful bacteria are those which make it possible for man to use sponges by ridding them of t lu- soft, slimy substance with which they are filled when alive, as well as the bacteria which soften the useless parts of the flax plant so that the rest of it may be separated and made into linen. When food, air, warmth, or moisture is not sufficient, bacteria cease to grow and go into a resting state. That is, they change their form, and surround themselves with a substance which protects the soft protoplasm from being harmed by freezing, heating, or drying. The simple 346 THE SMALLEST PLANTS (BACTERIA) plants all do this, but the simpler the plant, the more easily does it resist. It is this ability to withstand un- favorable conditions and to resume growth when condi- tions change for the better that makes bacteria such " good friends and such bad foes." LABORATORY STUDY OF BACTERIA Prepare culture plates of agar-agar from the following formula : Agar-agar Formula for 1000 c.c. Agar-agar 1 15 grams Beef extract 3 grams Peptone 10 grams Salt 5 grams Water 1000 grams Boil material for the agar-agar formula ; add sodium hydrate till the color of litmus paper is not changed ; cool to about 56 C, and beat into this one whole egg, including the shell. Warm slowly to the boiling point and continue till the egg is firmly coagulated; then strain the clear medium through a cheese-cloth on to moist cotton in a filter funnel. Work rapidly. Cool, and then boil once more. Filter through cotton into test tubes. Each tube should not be more than a quarter full. Plug the tubes with cotton. Then sterilize this mixture in the test tubes by placing them upright in water and boiling twenty minutes on each of three successive days. Let part of the test tubes cool, having the plugged end elevated half an inch. These are called slant agar tubes. When petri2 cultures are needed, melt up a sterile agar tube and pour into a sterile petri dish. 1. To show that bacteria are present on one's hands. Draw the fingers of the u.nwashed hand across the surface of the agar-agar in petri dish. Cover and set away for four days at room temperature or two days at body temperature. 2. To show that fewer bacteria are present on freshly washed hands. Draw the fingers of the washed hand across the surface of the agar-agar. Cover and set away. 3. To show that bacteria lodge under the nails. Place on culture plates scrapings from under finger nails, (1) before washing the hands, (2) after washing the hands. 1 Secured at most drug stores. 2 Flat, round dish with cover. BACTERIA IN RELATION TO MILK 347 4. To show that heating milk reduces the number of active bacteria. Sprinkle drops of milk and water on agar-agar pctri dish, 1 oatu milk, (2) pasteurized, (8) boiled. (I'sr mv tenth milk and nine tenths sterilized water.) 5. To show that bacteria change the medium in which they grow. Besides the number, form, size, and color of the colonies, note whether any change takes place in the agar-agar. 6. To show that bacteria grow best in the presence of warmth and moisture, compare those grown under such conditions with th »wn in a dry or a cold place. Note the influence | a | of warmth. (6) of cold, on the rapidity of growth. 7. To show that bacteria are in the air, expose the surface of the cul- ture plate for a few seconds. 8. To show that flies distribute bacteria. Let a My walk across the surface of the agar-agar in the petri dish. If bacteria have an opportunity, they work od every- thing which is capable of decay, and so we need to know how to prevent their working upon food and other things which we do not wish to ''spoil." Several ways in com- mon use are : (1) cold storage, where there is not warmth sufficient for the growth of bacteria: (2) the use of salt and other chemicals to prevent their getting a start, as in the curing and smoking of meat; (o) drying fruit and meat, thus removing water, a necessary condition for growth; and (4) heating fruit, vegetables, milk, etc., and sealing them in cans or jars while hot, thus killing any bac- teria the substances may contain and keeping all othi out. Anything prepared in this way is preserved by being made sterile or aseptic (Greek, sepein^ to make putrid). 246. Bacteria in Relation to Milk. — (Sec also Part II.) Milk as it comes from the healthy cow is practically I: from bacteria of any kind. The number of bacteria present. however, is not of so much importance as the kind. But if a large number of bacteria are allowed to get into the milk, some of them are sure to be harmful and may find 348 THE SMALLEST PLANTS (BACTERIA) conditions so favorable for their growth as to make trouble for the person using the milk. A high grade of milk will not contain more than 500 to 1000 bacteria per cubic centimeter. Such milk has been well cared for and comes from healthy cows. Some cities permit milk to be sold that contains as many as 100,000 and some even more bacteria per cubic centimeter. Such milk comes from unhealthy cows or dirty barns, or has been kept too long, or has "changed hands " too many times. To deliver pure milk to the consumer costs the producer time, care, and money, and consumers should be willing to pay more for milk which has had proper care. Ice prevents harmful bacteria from multiplying sufficiently to make milk dangerous, unless the milk is kept for too long a time. Preservatives, soda, borax, boric acid, formaldehyde, and the like are sometimes used to prevent the growth of bacteria. In some cases no immediate harm seems to come to the persons using milk thus preserved, but some of these substances are poisonous, and pure milk, properly cared for, does not need them. So the use of any milk in which preservatives are found should be avoided. A harmless bacterium gets into milk kept too long and forms lactic acid, thus giving the milk a sour taste and causing it to curdle. Sour milk is perfectly wholesome for food, but the taste is disagreeable. In 1857 Pasteur dis- covered this bacterium. He also found that milk could be kept for several days without becoming sour, after it had been heated sufficiently to kill this bacterium. Figure 369. — Clean Milk. Showing oil globules. Louis Pasteur (1822-1895) was a celebrated French chemist and biologist. After filling various academic positions. Pasteur was appointed Professor of Chemistry at the Sorbonne. in Paris, in 1867 Pasteur is especially famous for his researches in bacteria. In 1884 he discovered a method of curing or preventing hydrophobia by inoculating with the poisonous virus in an attenuated form. In 1874 the French government gave Pasteur a pension of twenty thousand francs, which they increased the following year, in consideration of his services in science and industry. SOURCES OF DANCER IX MILK WW) This process, called after its discoverer pasteurization, consists in heating milk for twenty minutes al a tempera- ture of 60° C, or to a higher degree for a Bhortei time, and then cooling it rapidly. This procedure kills nearly all the bacteria in the milk and does not change the taste or make it hard to digest. Milk is not rendered abso- lutely sterile, but it is a much safer food, especially for infants. At best pasteurization is only a corrective or precautionary measure, and we should demand that milk be kept clean and thus free from bacteria. Most raw milk products have their own forms of bacteria, but most of these forms are helpful. The flavor of June butter is imparted by a bac- terium different from the one in January butter. So with cheese, each brand or flavor receives its taste through the action of a special bacterium. At every step in the use and manufacture of milk, it is necessary to know the conditions under which the helpful bacteria work best, and how to keep out the harmful on 247. Sources of Danger in Milk. — The cow herself may be unhealthy and her disease transmitted through the milk. Of the several diseases which this animal may give, tuberculosis is the most common. Children are more liable than adults to take the disease in this way. There is no necessity to be in doubt about a cow's being infected with tuberculosis, for in 18lJ0 Koch discovered the tuberculin test, which enables the dairyman to detect the disease. This test is now commonly applied and in some cities owners of herds which have been tested and Figure 370. — Dirty Milk. 350 THE SMALLEST PLANTS (BACTERIA! found free from disease are allowed to sell their milk as "certified," though the meaning of this term varies. Not only is the raw milk from tubercular cows dangerous, but also the butter and cheese made from it. Bacteria multiply rapidly and remain active while milk is warm, and so it should be cooled as soon as possible after it has been taken from the cow. Milk should not be used when it is too old, for in that case the harmless bacteria may all have died and harmful ones taken their places. Milk should not be left in a metal container, nor open to the air, nor placed in an ice chamber where it can absorb the odors of other foods. Ice cream should be eaten only when fresh, for poisons (ptomaines) are formed by the action of bacteria, especially in ice cream which has been melted and then refrozen. Ice cream should be made under clean and healthful conditions, and should never be exposed to the air of the street. Men ivho made the Study of Bacteria Possible. — The inventor of the microscope should be placed at the head of the list of men who made the study of bacteria possi- ble, for without this instrument we should not know that such plants exist. We do not know who the actual in- ventor was, but the microscope was little more than a toy until it was improved by a Dutch naturalist, Leeu- wenhoek (Lu'wen-hook) in the latter part of the seven- teenth century. Next in the study of bacteria comes Pasteur, who discovered and studied them in their rela- tion to the souring of milk and in other fermentations. Figure 371. — Beef Jelly. Exposed in sanitary dairy. HEALTHY BODIES AND BACTERIA 351 Finally comes Koch, who discovered a way of separating bacteria so that each kind may be studied by Itself, a method called getting a "pur.' culture," and who aJ invented the tuberculin test. Most of our facts about bacteria have been learned during the past thirty-fi years. 248. Healthy Bodies and Bacteria. — So much has been said about harmful bacteria that a word of caution is needed. Two facts should make us take a sane view of the situation : (1) for every harmful bacterium there are thousands of helpful ones ; and (2) harmful ones cannot do their work, or even live, in a perfectly healthy body, for such a body is constantly preparing a substance (antitoxin) which neutralizes the bacterial poison (toxin). Our chief aim, then, should be to keep well, and a few simple rules of hygiene will accomplish this. (1) Spend as much time as possible exercising in the open air. (2) Sleep as many as eight hours out of twenty-four in a well-ventilated room or out of doors. (3) Bat only food which agrees with you, and not too much :> Figure 374. — Yeast. cess alcohol is formed and carbon dioxide is sel five; (3) the yeast lives on the proteid substances in the flour; (4) both the gas which makes bread Light and the alcohol are driven off by the heat of the oven when the bread is baked. Use is made of the enzymes and yeast in the making of beer, ah , and porter. The pro- cess of the manufacture of these products is as follows: The grain, usually barley, is soaked in water to soften it. The grain is kept warm and moist until it sprouts, and in this condition is called malt. It is then heated and crushed. Fermentation tal. place when warmth and moisture are supplied, the enzyme diastase breaking up the starch into sugars. The liquid or wort from this process is boiled with hops. The wort is again fermented, this time by tin- aid of yeast, the action of which is to break up the sugars into carbon dioxide and alcohol. Yeast of only one kind is used (a pure culture) and care is taken to keep the tem- perature favorable to its most rapid growth. As the yeasl grows and breaks up t lie sugar, it forms quantities of gas and alcohol. In bread these are temporary by-products which are lost in the baking, but in the manufacture of Figure 375. — Fermentation Tubes. 356 FUNGI beer they are the product sought, and every means is taken to retain them. Before the action of bacteria and yeast were understood, much trouble was experienced in getting uniform products, owing to the presence of undesirable bacteria and yeasts. The possibility of making pure cultures, the use of the microscope, as well as the tests which are made in the laboratories at every step of the manufacture, have placed the industries of bread-making and brewing on a scientific basis. 251. Reproduction of the Yeast Plant. — The method of reproduction of the yeast plant is similar to that of the bacterium, but differs from it in that instead of dividing: exactly in two, a bud usually pushes out from the side of the mature plant. Sometimes the second plant will form a bud before it breaks awa}^ from the first, and so a chain is made. Oftentimes a single plant puts forth more than one bud (Figure 374). LABORATORY STUDY Prepare a Pasteur solution, a good food for yeast, as follows : Potassium phosphate 10 parts Calcium phosphate 1 part Magnesium sulphate 50 parts Ammonium tartrate 50 parts Cane sugar 750 parts Sufficient water to make a total of 5000 parts. (This may be used for the culture of other molds than yeast and also for bacteria.) Yeast. — Examine yeast cells under low power. Note their glistening appearance and their number. Under the high power try to find all parts of a typical cell. Label and draw. Look for budding cells and chains of cells. Draw. Make a thick paste of water, yeast, and flour. Put an equal amount into each of three tumblers. Place one tumbler in a cool place. Into one of the remaining stir a teaspoonful of sugar and set both tumblers in a warm place. Examine several times a day and write down all the differences you observe in the three mixtures. Try to give a reason for everything you observe. BREAD MOLD 357 252. Bread Mold. — When examined with the naked eye, bread mold appears like a thick mass of felt, made up Figure 376. — Bread Mold. of colorless, closely interwoven threads. These threads are called hyphce (hi'fe: Greek, hyphe, web) and are of two kinds, one lying on the surface of the bread or just below it, and the other standing upright above the surface. The first are the nutritive hyphaB, and Figure 377. - Mold Grown from Water. Figure 378. — Cap Fungi. the second the reproductive. On the ends of tin- latter are round black bodies which are full of Bpores, each of 358 FUNGI which is capable of producing a new mold plant, if it falls into a place where conditions are favorable for growth, — that is, where it has plenty of food, the right degree of warmth, and sufficient moisture. Other kinds of fungi may usually be found on a loaf of bread after a day or two, as spores of many kinds of molds are floating in the air at all times (Figure 376). 253. Other Fungi. — A common fungus is the one that kills flies in the fall. At that time a dead fly is often ob- served on a window or mirror, the body surrounded by a whitish ring. Such a fly has been killed by fungus hyphre which have filled the body. The ring is composed Figure 379. — Puffballs. Figure 380. — Puffballs. of spores thrown off from the ends of the hyphse which have burst through thin places between the segments of the fly's body. OTHER FUNdl 359 Figure 381. — Bracket Fungus. The fruiting body of the fungus. Figure 383. — Pear Scab. Figure 382. — Tree Killed by Bracket Figure 384. Si tion through Fungus. the Scab. 360 FUNGI - I •.*•; \Wd - • Other common fungi are potato blight, red rust of wheat, corn smut, which produces the black mass found in an ear of corn, and the bracket fungi, which grow in large numbers on the trunks of trees and whose hyphae cause the death of the tree (Figures 381 and 382). The fungi used for food are nourishing, but there is a prejudice against their use be- cause other fungi which re- semble them closely are poison- ous. As a matter of fact, it is an easy task to learn to dis- tinguish the edible from the poisonous fungi. While the harmless fungi are now used as food much more than formerly, only a few varieties are raised for trade purposes (Figures 378-380). aX£3 Figure 385. — Spores. Section through a leaf injured by fungus. LABORATORY STUDY Wet a piece of bread, put a tumbler over it, and set it in a warm place for three or four days. Examine without the microscope to get the general appearance. With the microscope note (1) the clear, colorless threads (hyphae) making up the mass ; (2) the groups of spore-bearing bodies, black and round, on the ends of the upright stalks; (3) the spores coming out of them. 254. Lichens. — Lichens (H'kens) are grayish green plants which look like scales. They grow on old fences, rocks, trees, and the like and are especially noticeable after a rain. A lichen is made up of the hyphse of a fungus, which inclose the cells of an alga. The algal cells in a flat lichen are usually near the top and bottom, and the fungus is in the middle of the plant. The alga uses the moisture which the fungus collects and brings to the plant, and, by the use of its chlorophyll, makes food, a LICHENS 361 part of which is used by the fungus. The Latter, after it has become ac- customed to the alga, cannot live apart from it, and the alga, while it can live by itself, appears plump and pros- perous when it is found surrounded by fungal threads. The partner- ship, therefore, seems to be helpful to both plants. Such a relation between organisms is known as symbiosis (sim-bi-6'sis: life together ; Greek, syn, with ; bios, life). (Figures 386 and 387.) Lichens are interesting chiefly as representing this peculiar interdependence of plants. They have lit tit- or no economic importance, although in the Arctic Regions they furnish a supply of food for the reindeer. We close the study of the simplest plants with the fungi. As in the ca of the bacteria, men have Bpenl their lives studying the fungi, especially those which cause disease. Much lias been accomplished, but a great deal remains to be done in finding out the cure for certain fungus diseases, espe- cially those that attack vegetables which tion of Lichen. W6 use for food. Figure 386. — Lichens. 362 FUNGI FIELD TRIP FOR THE STUDY OF LICHENS After a rainy period, examine trees, rocks, old fences, posts, and sim- ilar places for lichens. Note the form, color, and kinds of trees having the greatest number of lichens ; the trees having the smallest number, and the side of the tree having the greatest number. Make the same exam- ination during a dry period. SUMMARY Fungi are plants similar in structure to the algae, but they lack chlorophyll. On this account fungi cannot make their own food, but always have to use that pre- pared by another organism. As they lack chlorophyll, fungi cannot use carbon dioxide, and as a result that which they produce by respiration is cast off into the air, as is the case with animals and with green plants placed in the dark. The fungi which are most important economically are the yeasts used in making bread, or beer and other fermented liquors ; the edible mushrooms ; those that spoil food, as bread mold, and those which cause plant diseases, such as corn smut and wheat rust. Fungi reproduce by means of spores. The mutually help- ful relation in which fungi and algse live in the lichen is called symbiosis. Animals which show the same relation are of little economic importance in this country. Fiqure 388. — Spores of Corn Smut. A farm fungus. QUESTIONS What is the color of fungi ? Are they ever green ? Why not ? How does their food differ from that of green plants ? How does the yeast plant produce changes in flour ? In malt ? How does the work of bread REFERENCES 363 mold and yeast compare with that of tin- bean '.' What are lichens '.' Do lichens grow equally well on all Bides of a tree '.' On all fcn i How do they appear when wet? When dry '.' What colon do you find among them ? REFERENCES Atkinson, Mushrooms. Bennett and Murray, Cryptogamic Botany. Cook and Berkley, Fungi. Gibson, Our Edible Toadstools and Mushrooms. Marshall (The Nature Library). Mushrooms. Trouessart, Microbes, Ferments, and Mold-. Atkinson, High School Botany. CHAPTER XXV MOSSES AND THEIE ALLIES 255. General Features. — The plants in this group have more parts, stems, leaves, etc., than the fungi and algse have ; the chlorophyll is evenly distributed, and they tend to grow erect. The life history of the mosses is more complex than that of the simple algae (Figure 390). If a cushion of moss is examined, it is found to be made up of small plants packed closely together. At certain times of the year some of these plants have a stiff, wiry, brownish stalk, surmounted by a boxlike capsule, on top of which may be a shaggy cap or cover (Figures 389 and 390). 256. Habitat. — Mosses grow in moist places, for their rootlike rhizoids are not sufficiently developed to gather water from the soil. They thrive best in shady woods, on decaying logs, and on stones wet by spray. Another reason for their need of moisture will appear in the study of their reproduction. 257. Life History. — If a dry moss capsule is shaken, powdery spores, much like the " smoke " from a puffball, float off in the air. When these spores fall on moist ground, each sends out a mass of very small, alga-like 364 Figure 389. — Types of Mosses. LIFE HISTORY 365 threads which are called the pr<>t>>/i, ma (pro-td-ne'mA: Greek, protos, first ; nema, thread). These threads pro- duce buds from which leafy moss plants grow. The latter produce gametes (reproductive cells which reproduce sexually) and so the moss plants are called gametophytes (gamete plants). These gametes are of two kinds, eggs (large non-motile cells) and sperms (motile cells). The egg cells are produced in spe- cial vase-shaped organs called archegonia (ar-ke-go'ni-a), and the sperm cells in other organs called antheridia. Figure 390. — Diagram. Life history of moss. rhiroids Figure 391. Antheridial Plant. Figure 392. Archegonial Plant. When moss plants arc reproducing, both of the reproduc- tive organs are found surrounded by Bterile hairs at the 366 MOSSES top of the stems. Some mosses have both antheridia and archegonia on the same plant, while other mosses have only one kind on each plant. The moss plant which bears the antheridia is usually short and has on the top a rosette of leaves, in the center of which is the sex organ. Many sperms come from each of the antheridia, which move by the use of cilia when water is present, a film of dew being sufficient. The female moss plant has on its upper end one or more archegonia, each of which contains an egg cell. When the egg is ripe or ready to be ferti- lized, sperms may swim to it if water is present. A sperm enters the archegonium and fuses with the egg cell, thus forming a sexual cell, known as the fertilized egg cell. From this fertilized egg cell a sporophyte (spore plant) grows out of the archegonium. The sporophyte consists of a foot, a pad by which it gets its food from the gameto- phyte, the seta, a slender stalk, and the capsule or spore- case. While every mature gametophyte leads an inde- pendent existence, the sporophyte is a parasite. Thus in its life history the moss plant has two distinct generations, the gametophyte or sexual and the sporophyte which reproduces asexually (Figure 390). 258. Economic Value. — Mosses have little economic value, except in cold regions where some kinds are dug from under the snow for food for the reindeer. They are interesting as showing a stage of development of the higher plants. LABORATORY STUDY Moss (Polytrichum). Study moss plants and note the difference in size between the male and female plants. Make a drawing to show the difference in size and in the arrangement of the leaves. Select a female gametophyte which has a sporophyte. Draw and label the seta or stalk, MARCHANTIA 367 and the capsule, the box at the top. Look for moss plant- oil trees, &l the edges of sidewalks, and on damp soil. With tin- microscope examine archegonia and antheridia. When antheridia from fresh material used, the sperms can usually lit- seen escaping from tin- antheridiom. 259. Marchantia. — Marchantia is u plant belonging t<> I Do the moss group, which grows in vciv moist places. It has a thin, broad body or > * "-.- «3gn • > «, thallus (thal'ltis: Greek, thallos, a young shoot), which is green on the upper surface and brown or gray on the under side. In the middle of the thallus is a midrib. On the upper surface are diamond-shaped mark- ings, each of which lias an opening which leads to an air chamber below. On the under side are rhizoids, which hold the plant loosely to the soil. The marchantias are adapting themselves to a life on land, but they are Btill dependent upon water. Their reproductive habits art- like those of the mosses (Figures 391 and o\^2 ). Figure 393. — Marchantia. LABORATORY STUDY OF MARCHANTIA Examine pieces of the plant and identify tin- thallus. midrib, rhizoids, and markings. Examine the umbrella-shaped, aprighl branches which bear the antheridia or male reproductive organs, the branches with slen- der projections which bear the archegonis or female reprodnctivi ma With a microscope examine a cross BOCtiOD <»f the thallus, and ol the openings and air chambers. 368 MOSSES SUMMARY Mosses are much more complex than algae and fungi. Specialization is shown in the cells which gather and con- duct water, the beginning of the absorptive and conductive systems of plants. There is also the beginning of a sys- tem of getting oxygen. The life history of a moss repre- sents the alternation of generations, a generation which reproduces by spore (asexually), and one which repro- duces by egg and sperm (sexually). The generation which bears spores is the sporophyte, and that which bears eggs and sperms, the gametophyte. QUESTIONS In what respects are mosses more highly developed than algse, fungi, and lichens ? Why do mosses require so much moisture ? Give the life history of a moss. REFERENCES Leavitt, Outlines of Botany. CHAPTER XXVI FERNS AND THEIR ALLIES 260. The Group. — The ferns are the best known mem- bers of this group, but club-mosses and rushes (horsetail | also belong to the fern family. The study of coal mines has shown us that ferns are very old plants and that they were formerly much more numerous than at the present time. The plants of this group have real stems, roots, and leaves, and most of them are larger than the mosses. While the ferns are not so dependent upon water as the mosses, they grow best in cool, moist woods and in rich soil. 261. A Typical Fern. — The fern named pteris (Figure 394) is the best known and most widely distributed. The stem proper is underground and lives on from year to year, while the part above earth renews 869 Figure 394. Pteris. 370 FERNS itself annually. Some of these stems reach a length of ten or fifteen feet. They branch out and give off many fine roots. Leaves, termed fronds, form from the upper surface of the stem and grow up through the soil into the air. The stem of the pteris fern is composed of well-defined clusters of cells which are grouped into tissues. These tissues are : (1) the epidermal on the outside, which protect the stem ; (2) the fundamental, which make up the body of the stem and carry on most of the vital processes; (3) the mechanical tissues, variously grouped, which by means of their thick- walled cells give the stem firmness ; Figure 395. — Pteris Stem. Figure 396. — Fern Frond Showing Sori. Figure 397. — Sori Enlarged. and (4) the conducting tissue, which is made up of several different kinds of cells, all of which carry liquids (Figure 395). The conducting ti«sue extends into the leaves and LIFE II I STORY OF THE FERN 371 Figure 398. — Forked Veins of Fern. is the vein of the leaf. During certain seasons of the year, lines form along the margin of the under surfa of the leaves. These lines are made up of many minute reproductive bodies, the sporangia ( sj >6r-an'jl-a : Greek, spore, seed; \\ and a Figure 399. — Sporangia. 372 FERNS new fern plant is soon formed. The young plant remains attached to the prothallium and gains nourishment from Figure 400. — a, Position of Sori ; b, Section of Sorus. 4 it. As soon as the young fern is able to get nourishment by its own roots, it begins life as an independent plant and the prothallium dies. There is the same alternation of generations in the fern that occurs in the mosses, the 5pores Prothallium ■Protonema New Fern Figure 401. — Life History of Fern. prothallium being the gametophyte and the "fern'1 the sporophyte, but the latter is the longer lived and much the larger plant (Figure 401). RELATED FORMS 373 FIELD TRIP T( I GREENH< >i BE OF w« K)D8 TO 8T1 DY FERNS Note the color of the plants, the characteristic fern leaf with it .-, >t ii><» or central stalk, its pinnsB or leaflets, and also the method of unrolling from the base to the tip. Note the fruiting dots (sori | on the l «:i«k of tin- leaves. In what kind of soil are ferns found? l>" they gro^ best In the sun or in the shade? l><> the leaves remain green during the winu Note the underground stem and its rums. Look for bads and young leaves. Note the forked veins. LABORATORY STUDY Examine the cross section of a stem and note the different kind tissue. Draw and label: (1) epidermal tissue on the outside; 2 me- chanical, dark brown tissue in masses near the center; '■'>) conductive tissue, large Openings ; (4) fundamental tissue filling the rest of the space. With a microscope examine the epidermis on the under side of the leaf, noting the shape of the cells and the stomata. Pull off a bit of the epidermis and try to distinguish the green guard cells. Examine a sorus with low power of the microscope and see how it is made up of sporangia on stalks. 263. Related Forms. — Clul> mosses, horse- tails, and selag- inella (se-laj-in- el/la) are plants which belong to the fern group. Clul> mosses bear their spores in a spike on scales which are modified leaves. In appearance these plants are more like mosses than ferns < Figures 102 and 403). Horsetail, or equisetum, -rows in waste or 'lamp pla< Figure 402. b, Sporangium ; c, Spores. Figure 403. — a. Club Moss. 374 FERNS sporangial,.. cone" internode •- furrows collar of... teeth node- It is a hollow stem, with joints, a mineral coating on the outside of the stem, and the branches in a circle around each joint. The con- ductive tissue in this plant is arranged near the surface of the stem (Figure 404). Selaginella is seldom seen in northern latitudes, ex- cept in greenhouses (Figure 405). 264. Economic Importance. — The fern group, like the mosses, have little economic importance. The spores of the club mosses are used in making certain kinds of fire- works (especially those used indoors) ; also in drug stores to keep pills from sticking together. The plant itself is used in Christmas decora- tion. Horsetail, so named from its appearance, was formerly cut, tied in bundles, and used for scouring, and this accounts for its other name, the "scouring rush." 265. The Formation of Coal. — Ages ago ferns were more numerous than they are now and many of them grew to be as large as our present trees. Geologists tell us that the climate was warmer and more moist than it is now, and conditions especially Figure 405. — Selaginella. Figure 404. — Horsetail. SUMMARY 375 favored the growth of fern plants. Where these large ferns died and fell to the ground, great masses accumulated. As the earth's surface changed, these masses became covered with soil or water, and under tin- influence "i' heat and pressure they changed into coal. At tin- Bame time natural <_ras and petroleum, or rock oil, were formed. No coal is being formed at the present time, and when our present supply is exhausted, we shall have t<> find other sources of heat and power. SUMMARY Ferns and their allies are less dependent on water than are the alg;e, fungi, and mosses. They are more highly organized, as they have epidermis, stomata, mechanical tissue, conductive tissue, stem, roots, and Leaves. Their life history shows the alternation of generations, consisting of spore, protonema, prothallium, and sporophyte. Club mosses, horsetail, and selaginella are closely related forms. Coal was formed when ferns grew to the size of trees in regions which were then hot and moist. QUESTIONS What parts of the flowering plant are found in the fern '.' In an animal what corresponds to epidermal tissue? to conductive tissue ? to funda- mental tissue? to mechanical tissue? Compare the life history of a moss and a fern. Why can ferns do with less water than mose Illus- trate by diagrams or sketches the life history <>t" a fern. What plants related to ferns ? Tell how coal beds were formed. REFERENCES Bergen, Foundations of Botany. Bryophytes, page 277, Pteridophj page 286. Campbell, A University Textbook of Botany, Bryophytes, pa Pteridophytes, page -11. Curtis, A Textbook of General Botany, Chapters VII and VIII. Leavitt, Outlines of Botany. Bryophytes, page 108, Pteridophytes, | 204. CHAPTER XXVII THE CONIFERS (aYMNOSPERMS) 266. General Characteristics. — In passing from the ferns to the conifers, usually known as evergreens, we go from a Figure 406. — Conifers. At center and left. Note their undivided trunks. lower to a higher order of plants. With the exception of the corn and bean, none of the plants studied up to this 376 ri.xL' v// /•;/■: :;:: Figure 407. — Staminate Strobili of Pine. time bears seeds, but all reproduce by spores or by ferti- lized eggs. Most of the evergreens are seed-bearing tn which vary in size, but which are alike in having trunks that taper from the base to tip without dividing. Such trunks are called excurrent. The ever- green group contains the largest plants in the world and those which live to the greatest age. Their foliage is usually composed of dark green, needle-like leaves which remain attached to the tree for two or three years. Thus the trees always have some foliage and so are termed "evergreen." 267. Pine Tree. — The pine illustrates the plants of this family. The pine has all the parts of a dowering plant — stem (trunk), branches, roots, leaves, seed-producing organs, and fruit (cones). Stem. — The trunk does not divide, — a marked character- istic of evergreens. In a forest where trees arc crowded together and there is in consequence a struggle t<> get Light, 'he trunks grow tall ami m08t of the branches are near the top. A cross section of a stem shows a scries of rings, known as annual rings, by which the approximate age of the t: can be told. In the spring when all the conditions arc at their best and growth is rapid, the cells «»!' the tree art- large and thin-walled, strength being sacrificed to size. Figure 408. — Young Cone of Pine. 378 CONIFERS Figure 409. — Ripe Cone of Pine. But in the fall or during a dry time in summer, the cells formed are much smaller and the walls thicker. These small cells which show most plainly make up the annual ring. During a season in which long, dry periods occur, more than one ring may be made. From the center to the bark ex- tend lines which are made of pith and are known as medul- lary rays. The part of the stem where increase in thick- ness takes place is just under the bark. Branches. — The branches leave the stem almost hori- zontally and nearly in a circle around the trunk of the tree. In the pine they curve upward, but each kind of evergreen has its own habit of curva- ture in its branches. Leaves. — The leaves, called needles, are long, slender, and flattened on one side. They grow in bundles of two, three, four, or five needles, according to the kind of pine. The leaves, which are borne but once in a place, remain on the tree from two to five years and then fall off, leaving the branches bare except near the ends. Figure 410. — Other Cones. a, arbor vitae ; b, hemlock. PISE TREE 379 Moots. — The roots of the pine vary according to the kind of pine and according to the soil, but they are alwa extensive. Seed-producing Organs. — Early in the spring, two kinds of cones are found on the oew shoots which grow from the terminal buds. One kind looks like short catkins, and these cones are borne in clus- ters near the base of the shoot. They consist of scales arranged spirally around the central axis. Each scale bears two pollen sacs. These are the staminate cones (Latin sta, stand) or strobili. They wither soon after shedding their pollen, although they may remain on the tree for a year. The other kind of cone is short and thick, and is found at the tip of the shoot or on the Side of the shoot The splendid trunk in the ., .. r™ • • .1 is that of a cucumber tree. (Hugh near the tip. 1 his is the p Baker \ carpellate cone (female strobilus), which is made up of scales arranged spirally around a central axis. Bach scale near its base bears two ovules. When the pollen is ripe, each grain, being pro- vided with winjrlike air sacs, is easily blown about by the wind. Some of the pollen sifts into the carpellate cone through the spaces between the scales, which at this time Figure 411.-- A Virgin Forest of Mixed Hard Woods and Conifers in North- ern Pennsylvania. Figure 412. — Lumbering in New York. Figure 413. — Fire Slash. The scene of a great destructive fire in 1908. HABITAT 381 are separated slightly. Then the scales close together, the cones turn downward, and con- tinue to grow for sev- eral months (Figures 407-410). Fruit. — During the next year, the pollen grains which are shut up inside the scales Figure 414. Waste Land in Pennsyl- vania. The year previous to the taking of this grow into pollen tubes photograph this land was covered with a t c ,.-,. ,, virgin forest as shown in Figure 411. and fertilize the egg Logging has been followed by fire, which destroyed the humus and much of the surface soil, making the tract a barren waste upon which it will be impossible to grow another such forest for many years. Pennsylvania alone has several millions of acres of such waste land covered formerly by splendid virgin forest. cells which develop in the ovules. From the fertilized e^ors the em- bryo pines develop. When the cones are about two years old the scales open, and allow the seeds to drop out. Bach seed is provided with a wing by which it is blown about, for the pine depends <>n the wind to Bcatter its seeds as well as its pollen. Because 1 1 ds li<" on the scale without being Inclosed in an <»\ av\ . all these plants are called gymno9p< rm% < ( rreek, gymnoS) naked : >/" mt. 268. Habitat — The Figure 415. — Waste Land. After the fire had passed over the region evergreens ?row m shown in Figure 413. - 1 1 1 < 1 \ soil in temperate 382 CONIFERS Figure 416. — Fire Train in the Adirondacks. Figure 417. — Nursery Where Young Trees are Started. RELATED FORMS OF CONIFERS 383 or in cold climates, but ;i lew <>f them occur where it is very warm. The finest evergreen forests in the world are found in the western part of North America, on the slopes facing the Pacific Ocean. 269. Related Forms of Conifers. — • Hemlocks, spra . firs, and balsams have smaller, flatter needles than the pines and they are not arranged in bundles. Cedars have scale- like leaves. Larch and cypress trees shed their Leaves in the fall, but in other respects are much like the pin FIELD STUDY OF GYMNOSPERMS Most of the work in connection with gymnosperma Bhould \«- d out of doors. The student Bhould learn to know by Bight all tin- local native evergreens and those commonly planted for ornament. He Bhould note the method of branching and the character of the trunk compared with other trees. He should observe the position <»f the cones on tin- branches and be able to give the reasons therefor. In the spring he should look for the male and female cones or strobili, and for leaf buds in the winter. He should examine the leaf sears and the external ru which mark a year's growth, and decide how many years each tree k< • its leaves. He should note the arrangement of the haves on the brand] the annual rings in the wood and their relation to the grain of the wood, the resin on wounds, the curvature of the branches, and the other : tures readily observed. STUDENT REPORT N t: l I > I B8 MM.I B A i.i i:i:\ \ i i: • Nbedlbs Needles is . i - -. \i ■ i no. in m « i bs i. \ 3 m Hemlock White Pine Larch Cedar . Spruce . Etc. . . . 384 CONIFERS LABORATORY In the laboratory examine a cross section of the stem to see the dif- ference in the cells grown in the early and in the late part of a season. Note the pith and medullary rays. If specimens are available, examine sections of wood from different trees. Make a collection of the woods found in the vicinity. Examine scales from staminate and carpellate cones. With the microscope examine pollen of pine. Draw and describe all the rays. 270. Economic Importance. — The value of the gym- nosperms can scarcely be overestimated. Most of the Figure 418. — Planting Young Trees in the Adirondacks. trees are sawed into lumber for building purposes, but some of them are used in their natural form for telegraph poles, masts of ships, and timbers of mines. Wood pulp, from which most of our paper is made, is produced from small spruce trees. The by-products of this group of trees are of great value. From the pine come tar, pitch, turpentine, and resin, while the bark of the hemlock was formerly extensively used in tanning leather. IMl'oUTANCE OF FORESTS 385 The forests of the United States cover about 550,000,000 acres, or more than one fifth of the total area. "Generally speaking, countries having over twenty per cent of wood lands have fores! resources sufficient to supply their lumber industries and their firewood con- sumption, provided that such area is properly stocked and conserved." — Schenck, "Fores! Policy," page 71. Yellow pine, which supplies one third of the Lumber consumed in the United States, ranks first in value ; white Jk.jL. »»•»?■.«-— ^ j M^ mt + ta^*-. . 4 Figure 419. — Young Plantation in the Adirondacks. pine, which formerly supplied the greatest amount, ranks second; and Douglas fir, third. 271. Related Topics. — Hardwood forests are compos of trees which have broad leaves and flowers with typical stamens and pistils. Such trees grow either alone or in tracts containing many evergreens, Maple trees supply sugar and syrup, the industry being important in Ohio and Vermont. Other hardwood trees yield fuel, Lumber, and nuts. 272. Importance of Forests. — Forests are of the test importance in preventing floods caused by the rapid melt- ing of ice and snow. The snow melts more Blowly in the 386 CONIFERS woods, not only during a midwinter thaw, but also in the spring, and the soft, porous character of soil causes it to absorb much water. This results in springs and rivers being fed uniformly during the summer. Floods and freshets can often be traced largely to denuded hills along the streams, because hills without forests have soil poorly Figure 420. — Young Plantation 16 Years after Planting. fitted to prevent the water from running down faster than it can be carried away. Floods and freshets each year do millions of dollars' worth of damage in the de- struction of bridges, buildings, and other property. Another loss occurs in the washing away of the most valuable form of soil from the hills, when the water flows off rapidly. Not only is the soil that is left useless for IMPORTANCE OF FORESTS 387 Figure 421 . — Pollen of Pine. agriculture for many years, l>ut that carried into the streams clogs harbors and channels, making it accessary to spend large sums in dredging. Forests arc destroyed not only by lumbering operations, but also by fires, many of which are caused by carelessm Forest fires, in addition t<> destroying the trees, render large territories useless for agriculture by burning up the humus, or organic part of the soil. So great is the destruction and waste caused by forest tires, that the national and state governments have taken measures to prevent them. Forests are now patrolled daily during parts of the }Tear and apparatus for fighting fires is always in readiness. In addition, the government is setting out thousands of young trees and protecting them in an effort to re-fon bare territory, especially around the headwaters of rivers. Where forests still exist, the government is buying them in order that they may not be destroyed. Such tracts are called forest reserves. In European countries the study of forestry lias been carried on for a long time. Their forests are made ,i source of revenue, but all the 1 1 are never cut in a single season, and planting keeps pace with cut- ting. Scientific forestry is now practiced on aboul i"1',' of the public forests of the I Ihited States and on about 2% of the woodlands privately owned. Only about one fifth of the wooded area of the United States is under government control. New York Si.it.- is taking steps to preserve her forests and also to re-forest large tracts which have been out over (Figures IIs 120 >• ■ " "H. ..-'. N n y \ V^ e£ '..'. \ Figure 422. — Seed of Pine. 388 CONIFERS SUMMARY The conifers belong to a class of the higher plants. They have periods of active and less active growth, both together resulting in the appearance of annual rings. Because their seeds are not entirely inclosed in an ovary, but lie uncovered on a scale, they are called gymno- sperms. Conifers are of great economic importance, for they supply much of our lumber, tar, pitch, and all our turpentine and resin. Hardwood trees grow with the evergreens. They belong to many families of flowering plants and furnish lumber, fuel, and nuts. Forests help to regulate the flow of streams and they prevent the washing away of the soil. QUESTIONS How are gymnosperms like other plants ? How do they differ from other plants ? What kind of a trunk is characteristic of gymnosperms ? How does a tree which grows in a forest differ from one which grows in an open field ? Why ? What are annual rings ? How are they formed ? Describe the branches ; the leaves ; the roots ; the cones or strobili ; the fruit. What is a sporophyte ? Name the gymnosperms. Make a list of the uses to which lumber is put. What other products come from the evergreen forests ? In what ways are forests beneficial ? What are the governments doing to protect them ? What regions in your own state are covered with forests ? REFERENCES Government pamphlets and bulletins. Hough, American Woods. Keeler, Handbook of Trees. National Geographic Magazine. Sargent, Trees of North America. Schenck, Forest Policy. CIIAI'TKR XXVIII PECULIARITIES OF PLANT LIFE 273. Unusual Plants. — hi order to live, all plants must. have conditions favorable to their vital processes, and many of them develop special modifications which aid the plant in the struggle for existence. Sonic of the modi- fications already studied in this book arc the arrangement of leaves or the length of petioles to secure air and light ; the presence of color, odor, and nec- tar, devices to attract insects and thus secure the pollination of flowers ; and the use of wings, pappus, and hooks to secure the distribution of seeds. Many of the carnivorous and parasitic plants are remarkable for the modifications which make it possible for them to obtain nitrogen, an clement lacking in the food supply of their particular environment. Tfie Pitcher Plant. — The leaves of this plant form a sort of vase which retains water in the bottom. When insects crawl into the leaf, their escape Is prevented by hairs which grow around the opening on the inside and point downward, and the unfortunate victim, exhausted 389 Figure 423. Photograph of Pitcher Plant. 390 PLANT PECULIARITIES by his struggles to get out, falls into the water and is drowned. When the bodies decay, the plants secure the nitro- gen which they are un- able to get through their roots. The Sundew. — This plant has round leaves covered with long glandu- lar hairs which secrete a sticky substance. When an insect alights on a leaf, the hairs bend over and hold the victim until it dies, the secretions of the plant meanwhile digesting the soft parts of the insect. When the leaf has Figure 424. — Leaves of Pitcher Plant. Figure 425. — Photograph of Sundew. UNUSUAL PLANTS 391 absorbed this digested food, the hairs release the remain- ing parts, which then fall off, and the hairs resume their usual position. Venus* Fly-trap. — - This plant has another waj to catch insects. The leaves end in a traplike device in two parts which lie flat like the Leaves of a 1 k. When an insect alights on one side, the other clo quickly and confines the Figure 426. — Diagram of Sundew. Figure 427. -Venus's Fly-trap. fly by bail's on the edge which interlock. Digestion and absorption soon take place, after which the Leaves lie flat again, ready for another insect visitor. Indian Pipe. — Although it produces flowers and seeds, this plant has no chlorophyll and BO is a waxy white in appearance. It gets its nourishment from decayed organic 392 PLANT PECULIARITIES matter, usually wood, just below the soil. A fungus which grows on the roots helps them to absorb this prepared food. Mistletoe. — We are most familiar with this plant as a part of our Christmas decorations. Mistletoe has chlorophyll and so is able to manu- facture its own food, but it has no roots for ab- sorbing water, making it dependent on a larger plant for this necessary part of its vital condi- tions. The plant possesses absorbing organs which pierce the bark of the trees upon which it grows. As a result it does much injury to the trees by using the water which they need for their own life processes. In the South, for instance, the mistle- toe is regarded as a great pest. 274. Movements of Plants. — Most plants move slowly and only in response to one of several stimuli. Touch, or contact, is the stimu- lus in the case of sun- dew and Venus's fly- trap, both of which are Figure 429. — White Waterlily. Figure 428. — Photograph of Birch Roots. Growing over the surface of a boulder. PLAXT SOCIETIES 393 peculiar in moving quickly. Tendrils curve undei the influence of the same stimulus, but they move slowly. Light and darkness arc universal stimuli. Flowering plants move toward the Light, it" it docs nol surround them evenly on all sides. Window-growing plants Bhow this. Plants like potatoes, which sprout in a cellar, grow many Figure 430. — Waterlilies — Hydrophytes. feet to get into the light. Darkness causes plants like clover and oxalis to close their Leaves. Moisture is a stimulus which affects the roots of a plant, as is shown in Figure 428. 275. Plant Societies. — The term plant society is applied to any collection of plants which grow under similar con- ditions. The trees of the forests, and thegrass and weeds of our lawns, are typical example-. In mosl cases water, or the lack of it, is the basis \'^r classifying or grouping plants in societ ies. Plants, Like some alga*. Live submerged in the water, while others. Like the waterlilies. Live 394 PLANT PECULIARITIES partly in the water, lifting their leaves and flowers into the air. Plants which live in the water are called hydrophytes (hy'dro-fltes : Greek, hydor, water; phyton, plant). If such plants have roots, they are little more than holdfasts, for the hydrophytes do not need organs of absorption. Most of the members of this plant society are without Figure 431. — Cat-tails and Arrow-leaf. mechanical tissue, for the water holds them firmly on all sides. The alg?e lack a conducting system as well, for their source of food is all about them. Waterlilies get their oxygen and much of their carbon dioxide from the air through their leaves, which float on the surface of the water with the stomata on top. Air passages in the long, slender steins convey air to the roots which lie in the mud. Hydrophytes which lie under water have their leaves finely divided to offer as much surface as possible to the water and thus secure a full supply of oxygen. PLANT SOCIETIES 395 Figure 432. — Giant Cactus. Figure 433.- Sage Brush. 396 PLANT PECULIARITIES Figure 434. — Diagram. Section of the epidermis of agave, "a xerophytic plant. Compare this sec- tion with the section of the bean leaf in Figure 265. Plants which live in desert regions, of neces- sity, have to live on little water. They are called xerophytes (zeVo-fites :. Greek, xeros, dry ; phyton,. plant). Xerophytes usu~ ally have long roots so- that when moisture is- present they may gather it rapidly. Many forms have little surface ex- posed to the air ; the branches are few, and there are no leaves. The stem, which is green in color, perforins the^ work of photosynthesis. To conserve their water supply further, the xerophytes have a thick epidermis and few stomata. These plants are an admirable illustra- tion of making the most of what one has. Desert plants live in regions where it is usu- ally both hot and dry, but plants of the Arctic Regions have many of the same modifications, only in a lesser degree. Much of the time severe cold prevents the roots from absorbing water, and the plant must keep what it already possesses. Some of the Arctic plants, Figure 435. — Bull Thistle. therefore, have leaves A mesophyte weed. PLANT SOCIETIES 397 which roll to reduce the surface and have, in ad- dition, a coating of hairs, both devices for retard- ing transpiration. Most of the plants which we see and which live where there are no great extremes of heat or cold and where it is neither wet nor dry are called mesophytes (mez'o- fites : Greek, mesos, middle ; phi/ton, plant). They have few charac- teristics in common, but all have roots suited to the soil in which they grow, and leaves which in shape and arrangement serve the purposes of cadi plant better Figure 436. — Lady Slipper. I'fc) Mi > si Ml B S r«? •**?! ^B^^B w^. ^ffC [j| \^ V Br ^^^fl| p>^ ^mZ^i LM.i^mk y+- jf Figure 437. — Long-spurri 398 PLANT PECULIARITIES than any others would do. Examples of this are the nar row, upright leaves of the grass, which grows thickly ~& 1/ - -. . - Figure 438. — Mistletoe. A semi-parasite. This tree has no leaves. crowded together, the broad leaves of the trees, and the leaves of the ivy, which grows on walls, arranged like a mosaic. Many divisions of the mesophytes might be PLANT SOCIETIES made, for some prefer sunn \ local imis, <>t hers shadv plaot and so on. Plants which live in tin called epiphytes (ep'l-fites : plant) because they usu- ally attach themselves to the stem of a larger plant. Their modifica- tions consist of one kind of roots for fixing them to their support and another capable of ab- air make up another group, ( ircck. epii upon : phyton^ a sorbing and storing water. The latter or- gans are called velamens and are composed of spongy tissue. They are situated on the out- side of the plant, soak up rain and dew and conduct it to an inner region where it is used as the plant needs it. Velamens can also ab- sorb moisture from the Figure 439. — Diagra- Sectional view of a branch infected with mistletoe, showing the relation be- tween the parasite and host ; a. branch of host tree ; b. mistletoe ; c. primary sinker; d, sinker from cortical root; e, /, cortex of soft bark ; g, cambium or growth ring; /;. wood of branch. The starving and dwarfing of the branch beyond the mistletoe is shown at ;'. air. The epiphytes are characteristic of the tropics, where the air IS full of moisture and where rains fall frequently. In OUT own part of the world, lichens lia\ imewhal tin- same habit, and orchids in greenhouses are another example. The study of plants which deals with their distribution and the factors which govern it is called plant < (e-kol'o-jy : (J reck, oikos, home; hgo$, talk). 400 PLANT PECULIARITIES 276. Plant Succession. — When a swamp is drained, a forest cleared, or a desert irrigated, plant conditions are changed. Thus it becomes impossible for some plants to thrive in their former habitat, and possible for others to grow where before they could not. The replacing of one plant society by another is termed plant succession. When a forest is cleared and the tract burned over, the plant called fireweed appears in large numbers, even if a culti- vated crop is planted. After a year or two the fireweed gives way to a growth of blackberry and raspberry bushes, which are later replaced by grasses and weeds of various kinds. Another example of plant succession is seen in regions covered by fresh lava from a volcano. At first nothing grows. Probably bacteria and fungi appear before other plants are noticed, but lichens are usually the first to be observed. These die and decompose, and their remains, together with bits of lava loosened by frost, wind, or water, accumulate in depressions and form a soil in which mosses can grow. The remains of the mosses add to the organic matter in the slowly increasing soil, and, in the course of time, ferns and larger plants can grow. The last finally replace the mosses as they replaced the lichens. 277. Summary of Our Interest in Plants. — Our first interest in plants is economic, that is, we think of them first in terms of their usefulness or harmfulness to us. As every animal in the world is dependent directly or indirectly upon plants for food, it becomes obvious to what a degree we are benefited by the ability of plants to make food out of the air and the soil. Man could live comfortably on what three plant families furnish, — the grasses, which include all the cereal foods and sugar; the pulse family, which furnishes most of our vegetable nitrogen ; and the rose family, which includes the SUMMARY OF OUR INTEREST IN PLANTS 401 plants which furnish us our luxuries in the wav of fruits. In eating animal products, man is still dependent apon tin- grass family to furnish food for the cattle from which be obtains meat, milk, cheese, and butter. For clothes, man depends indirectly upon plants for the Leather and woo] of the domestic animals, and directly for cotton and linen. F\'^l . 40*1 W* f ;£#" v«*tfd %x*, 5 ■ "^* 1 i ■: '$$'$>' JIB »tfV Mi « • ; ■ *" ^^2St^t * Iflttr' - Figure 440. — Tropical Vegetation. Note how different the plants are from ours. Plants are the source of many of the materials out of which houses are made and furnished. Some plants (bacteria) cause disease, while still others provide remedies with which to cure diseases. Plants please our eyes as we travel about. They keep up tin' supply of oxygen in the air ; they rid the air of tin1 carbon dioxide which we have cast off; they provide employment for millions of men who raise food plants, manufacture them into food, and distribute them throughout the world ; 402 PLANT PECULIARITIES and they employ other millions in the production of cotton plants and cotton cloth for our clothing. The farmer who raises plants has an interest in knowing what kind of soil and climate, how much water, air, and light each kind of plant needs to yield him the best results. To this end he has to know something about the habits of plants in general, and about their enemies and their dis- eases. He has learned by experience that some plants grow better when planted in hills ; others in drills, and still others sown broadcast. He is still trying to find the best kind of plant food for each plant, and the method of cultivation which best enables plants to get their full supply of food and moisture, and he is still fighting weeds which deprive the useful plants of their share of food, water, and light. Yet he is conscious, if he stops to con- sider, that he cannot make a plant grow. His part is to create good vital conditions. We are interested in the work of men who are trying by cross-pollination, grafting, and selection to reduce the undesirable parts of plants and to increase their capacity for food, storage or whatever we find desirable. Luther Burbank has made many experiments along these lines, especially in increasing the number of fruits on trees and in reducing the size of the seeds in berries. 278. Scientific Interest. — In addition to practical in- terests, that is, besides the supreme importance of plants to man and his dependence upon them, there is another interest, — that of the scientist in plants as organisms. The scientist studies how plants are like animals ; how they differ from them ; how each is dependent upon the other for waste products ; how plants depend upon animals for the pollination of their flowers and the scattering of their seeds, and how the plants make use of the wind and water for the same purposes. SCIENTIFIC IX TERES T 403 He studies, too, the increasing complexity of plants from the simple, one-celled plants dependent upon water for existence up through the plants which are becom- ing accustomed to living ou land, and finally to the which have complex: systems and complex Sowers. He finds that all are related, and the more be Learns about them, the more interesting does he find their relationshi] He is interested in seeing how the changfe from water to land calls forth changes in structure to fit the new environment ; how in land plants, each one has adapted itself in form, size, arrangement of leaves, and so on, to make the best possible use of the air and water which it is able to pro- cure. In trying to find the causes of such varia- tions of plants the scientist performs many experiments, often upon the smallest plant, for size and complexity arc no Indication of the interest which may center in a plant structure. Bac- teria, for instance, which are the simplest and smallest of all plants, are being st udied more to-day than any of the others. Every year adds to our knowledge of the nature of plants, their relations to each other and to man. Besides these relations due to their surroundings, plants bear I wards each other the relation of dependence and inde- pendence, which we have discussed under parasitism and symbiosis. Figure 441. — Calla. From an X-ray photograph. One of the new ways of studying plants. 404 PLANT PECULIARITIES Plant life itself remains a mystery. The poet Tenny- son has given expression to the thoughts of those who have tried in vain to solve the many problems which have arisen in connection with the study of plant life. " Flower in the crannied wall, I pluck you out of your crannies. I hold you here in iny hand, Little flower, root and all. But if I could understand What you are, little flower, Root and all, and all in all, I should know what God and man is." LABORATORY To show the response of stems1 to" gravity, place seedlings or young plants in unnatural positions and note their effort to right themselves. To show the response to light, examine a potato from a dark cellar, which has sprouted in the spring ; a plant that has been allowed to grow towards the light in a window ; the bending of seedlings, and the like. For the storage of food, examine all the common garden vegetables and test them for the food which they contain. If possible, find some vegetables which have been kept for two seasons and have produced seed, and note their appearance after all the food has been used. Sprout slips of balsam, geranium, and ivy to get adventitious roots. Show such roots on the stem of a tomato plant where it has been allowed to lie on the ground. Examine leaves in the laboratory and in the fields to find illustrations of all the terms used. Examine onions and cabbages for example of leaves modified for storage, and the onion also as an example of a re- duced stem. Find examples of all the terms used in the discussion of flowers and buds. AIM'KXDIX A BIRD STUDY Oxe of the most fascinat in-- phases of Biology is the Btudy of birds. This is easiest and mosl interesting during the migrations, when the trees arc leafless. The early morning is the best time of day for observing birds. The following tables have been compiled to help pupils acquire a more intimate knowledge of birds, — their appear- ance, habitat, food, manner of flight, and bo on. N«»t only is this information valuable in itself, but there are i'rw tlm that may be learned in such a pleasant way. ■Plait A- Brpour roo locrmriCATiON or Ribki s I i- S 8 is 5> 3 Is- 3 I 1 Or/ate tree larvae : Ttaltl MX ■ orange Ua \ I VtOB t)IJOK \'J"f r' strong Purple nncti tree fkfca I ■■ :■ : . ti adab ! : i. 0 tmm forked Suift flying insects dusKy dusky dusky dusky dta • . .' :• Solden Crooned kinglet tree . . / block .. ,/f fuscous fuscous qreenah forked Bluebird tree r, ' ;.v blue blue ? ..- ; I >, -i >■ : ■- -», //.. r'r ground lorper ■:■.■ scarlet tmuml : ■ "i /•'/>/// ground ■. me b*x h rufous ■ykitr. ■ ."' ?' trees shrubs nook '■■ smaller • 90 b*xM . - : Eft r -xy.t trees scarlet scarlet black scortet sooner '•;>■>; * Ural b«* lum rtc JVK«i«a g/*a •» mm* ttm r—mr 105 406 APPENDIX A Plate S- Dcuny Uoodpcckr t3 5uct — Report for feeding station — 1 %> § £ ■*3 O CO /to Light Above m bock doon t= -C; O Manner of — comina to food— i 13 -c: §> in Yes 1 Tu)0 "5" I 5 Yes /fairy rloodpccher Suet + /to Crumbs Suet /to Alignt Above uaiH doun Dead foremost Nuthatch Yes Yes Chickadee /to Fly directly to food Three Brwn Creeper Suet Alignt belocj ana ualh up /to One Song sparrou Seeds Crumbs Seeds Crumbs Suet Alight /tear ana hop nit Four No House or English Sparrou) Yes One Yes ~Robm Crumbs /to tnree Yes AIM Near UQIKtoif Grachle Yes Tuo /to Plate C- — Report f or Birds in Nesting Season — 3? "5 1 V) 4 Fj$o Adults Young n % I c 1 V) \ 1 N 1 1 1 ? -•J 1 Robin bedpe grass and mud — interlaced X X X Chipping Sparrou bush rootlets grass, hair 1 1 X X X Oriole dm fret plant fibre, grass, string uoven X X Grackle Voruoj Spruce grass and uool — inter/acea 5 grzen oroun gray li'lonp X Neadou Lark jrouna grass - 19 5 Oroun unite rr r» X Phoebe under eaves flair, mud feathers plastered, interlaced 4 uhite F " X Cat Bird oush rootlets, grass — interlaced 5 blue V" X Mourning Dove Horuaj Spruce grass X X X House Sparrow behind eave hay. grass, feathers , heaped X X BIRD STl'DY 40: P/ate D- — Pepori on a single ^a-r of Birds feedm. jng- to 1 I \ Aumber of rimes eocfi /test ling is fed — Direction from uhich Adurts approach nest 1 1 1 I V 1 1 5 315 AM X uorm X X X laun X 3 20 i * X tt - X X X X a 9 21 ii x it X X X a 9 28 ii X it X X X — X X 9 30 ii x cherry X X X X 9 40 - X oorm X X X X 3 45 •• X •■ X X X lovn 9 47 ii X - X X X n X 953 " X •• X X X X a Plate E- — Peport for Seasonal Activities of Birds — 1 1 CS.. .So s c o I u Color of young Color of /duff J C3 8 O c 5 & Aj -* ^ Robin Bluebird Chipping 5cmxj Gold finch Cedar Bird Bobolink Song Sparrou Sandpiper Houx Spanvu APPENDIX B REGULATIONS OF THE SANITARY CODE ESTABLISHED BY THE PUBLIC HEALTH COUNCIL OF THE STATE OF NEW YORK Condensed from the Bulletin of the New York State Department of Health Isolation of Persons Affected with Communicable Diseases. — It shall be the duty of every physician, immediately upon dis- covering a case of communicable disease, to secure such isola- tion of the patient as is required by the special rules issued by the local health authorities or by the state department of health. Adults not to be Quarantined in Certain Cases. — When a person affected with a communicable disease is properly iso- lated on the premises, except in cases of smallpox, adult mem- bers of the family or household, unless forbidden by the health officer, may continue their usual vocations, provided such vo- cations do not bring them in close contact with children. Removal of Cases of Communicable Disease. — After isolation by the local health officer no person, without permission from him, shall remove, or permit to be removed from any room, building, or vessel, any person affected with diphtheria, scarlet fever, smallpox, or typhus fever. Without permission from the local health officer no person shall remove, or permit to be removed from any dwelling, any person affected with chickenpox, diphtheria, epidemic cerebro- spinal meningitis, epidemic or septic sore throat, measles, mumps, poliomyelitis (infantile paralysis), scarlet fever, small- pox, typhus fever, or whooping cough. 408 SANITARY REGULATIONS U Removal of Articles Contaminated with Infective Material. — Without permission from the Local health officer do person shall remove, or permit to be removed from any room, build- ing, or vessel, any article which has been Bubjecl to contami- nation with infective material through Asiatic cholera, diph- theria, scarlet fever, smallpox, typhoid fever, or typhus I until such article has been disinfected according to the special rules and regulations of the 3tate department "I health. Exposure of Persons Affected with Communicable Disease. No persons shall permil any child, minor, or other person under his charge, affected with diphtheria, measles, scai lever, smallpox, or typhus fever, i" associate with others than his attendants. No person affected with any of -aid diseases -hall e\p himself in such manner as to render Liable their Bpread. Exclusion from School of Cases of Disease presumably Com municable. — It shall be the duty of the principal or other person in charge of any public, private, or Sunday school to exclude therefrom any child or other person affected with a disease presumably communicable until such child or other person shall have presented a certificate issued or counter- signed by the health officer, stating that such child or other person is not liable to convex infective material. Exclusion from Schools and Gatherings of Children of House holds where Certain Communicable Diseases Exist. — Evi child who is an inmate of a household in which there is, oi has been within fifteen days, a case of chickenpox, diphtheria epidemic cerebrospinal meningitis, German measles, measl mumps, poliomyelitis (infantile paralysis), Bcarlel fever, small- pox, or whooping cmi-h. shall be excluded from every public, private, or Sunday school and from every public or private gathering of children tor such time and under >uch conditio as may be prescribed by the local health authorities. Precautions to he observed in Chickenpox. German Measles. Mumps, and Whooping Cough. No person affected with chickenpox, German measles, mumps, or whooping cough shall 410 APPENDIX B be permitted to come in contact with or to visit any child who has not had such disease or any child in attendance at school. Isolation or Removal in Smallpox. — It shall be the duty of every health officer, whenever a case of smallpox occurs in his jurisdiction, if a suitable hospital is available, to remove or cause to be removed such case promptly thereto. Every in- mate of the household where such case occurs, and every per- son Avho has had contact with such case, shall be either vaccinated within three days of his first exposure to the dis- ease or placed under quarantine, and, when vaccinated, the name and address of such inmate or other person shall be taken and such inmate or other person shall be kept under daily observation. Such observation shall continue until suc- cessful vaccination results, or for at least twenty clays. If such inmate or other person refuses to be vaccinated, he shall be quarantined until discharged by the local health officer. If there is no hospital available, the patient shall be isolated and every inmate of the household shall be vaccinated or strictly quarantined until discharged by the local health officer. Whenever a case of smallpox occurs in his jurisdiction, it shall be the duty of the local health officer to use all diligence in securing the names and addresses of all persons who have had contact with such case, and in causing such persons to be either vaccinated or placed under quarantine. Maximum Period of Incubation. — Tor the purpose of this code, the maximum period of incubation (that is, between the date of the exposure to disease and the date of its develop- ment), of the following communicable diseases is hereby de- clared to be as follows : Chickenpox 21 days Measles 14 days Mumps 21 days Scarlet fever 7 days Smallpox 20 days Whooping cough 14 days SANITARY REGULATIONS -11 1 Minimum Period of Isolation. — The minimum period isolation, within fche meaning of this code, Bhall fc> follows : Chickenpox, until twelve days after the appearand the eruption and until fche crusts bave Eallen and the scan are completely healed. Diphtheria i membranous CTOUp), Until two BUCCe881ve D( tive cultures have been obtained from fche nose and throat at intervals of twenty-four hours. Measles, until ten days after the appearance of fche rash and until all discharges from the nose, ears and throat hav< appeared and until the cough has erased. Mumps, until two weeks after the appearance of the d and one week after fche disappearance of the Bwellin Scarlet fever, until thirty days after fche development of fche disease and until all discharges from the nose, ears and threat. or suppurating glands have ceased. Smallpox, until fourteen days after the development of the disease and until scabs have all separated and fche Bears com- pletely healed. Whooping cough, until eight weeks after the development of the disease or until one week after fche last characteristic cough. Sale of Food Forbidden in Certain Cases. — When a case of diphtheria, epidemic or septic sore Jjhroat, amoebic or bacillary dysentery, epidemic cerebrospinal meningitis, scarlet t«\ smallpox, or typhoid fever exists on any farm 01 dair\ ] ducing milk, cream, butter, cheese, or other foods likely t<> be consumed raw, no such foods shall he sold or delivered from such farm or dairy, except under the following conditions ■ (a) That such foods are not brought into fche house wh such case exists ; (b) That all persons coming in contact with Buch foods eat, sleep and work wholly outside such hous< (c) That such persons do not come in contact in an\ way with such house or its inmates ox contents : 412 APPENDIX B (d) That said inmates are properly isolated and separated from all other parts of said farm or dairy, and efficiently cared for ; and (e) That a permit be issued by the health officer. Destruction of Foods in Certain Cases. — When a case of diph- theria, epidemic or septic sore throat, amoebic or bacillary dysentery, epidemic cerebrospinal meningitis, scarlet fever, smallpox, or typhoid fever exists on any farm or dairy produc- ing milk, cream, butter, cheese, or other foods likely to be consumed raw, the state commissioner of health or the local health officer may destroy or order the destruction of any such foods which in his opinion may have been so contaminated as to be a source of danger, and the local authorities may com- pensate the owner for foods so destroyed. Handling of Food Forbidden in Certain Cases. — No person affected with any communicable disease shall handle food or food products intended for sale, which are likely to be con- sumed raw, or liable to convey infective material. No person who resides, boards, or lodges in a household where he comes in contact with any person affected with bacillary dysentery, diphtheria, epidemic or septic sore throat, measles, scarlet fever, or typhoid fever, shall handle food or food products intended for sale. No waiter, waitress, cook or other employee of a boarding house, hotel, restaurant, or other place where food is served, who is affected with any communicable disease, or who visits in a household where he comes in contact with any person so affected, shall prepare, serve, or handle food for others in any manner whatsoever. Cleansing, Renovation and Disinfection Required. — Ade- quate cleansing of rooms, furniture and belongings, when deemed necessary by the local health officer, shall immediately follow the recovery, death, or removal of a person affected with a communicable disease. Such cleansing shall be per- formed by or at the expense of the occupant of said premises, under the direction of the local health officer. SANITARY REGULATIONS 413 Adequate renovation of premises, when <-al health officer, shall im- mediately follow the recovery, death, or removal of a \ ■• affected with a communicable disease Such disinfection Bha 1 be performed by or under the direction of the local health officer in accordance with the regulations of the Banitary o and at the public expense unless otherwise pursuant to law. APPENDIX C "WHAT PEOPLE SHOULD KNOW ABOUT CANCER Francis Carter Wood, M.D. Condensed from the Bulletin of the New York State Department of Health. Cancer not a Germ Disease. — The cause of cancer is still unknown, but this does not prevent our being able to cure it. The disease is quite unlike those due to germs, of which so much has been learned in the last thirty years, and no germ which is capable of causing cancer in human beings or in ani- mals has been found. Cancer is, therefore, not contagious, and there is no danger in treating or in dressing a cancer case. Ordinary cleanliness, however, requires that the soiled dress- ings shall be burned — not because there is any danger of contagion of cancer, but because the discharges and dressings contain germs such as those which cause boils, erysipelas, and other skin inflammations. Cancer not Contagious. — As cancer is not contagious there is no reason to believe the stories, so often told, of " cancer houses," or " cancer villages " or " cancer belts." The occur- rence of a large number of cases of cancer in a house can usually be shown to be due to the fact that the house has been occupied by old people. Since cancer is a disease of old age there will naturally be more cases of the disease in such a house than in one which has been occupied by a number of young people. Cancer not Hereditary. — Cancer is not hereditary, although much has been said and written about certain experiments with strains of white mice to show that, by inbreeding, the occur- rence of cancer in these animals is much increased. While 414 CAXCER 11.") there is no question that tins is a fact, yel the increase can be obtained only in certain strains of white mice, not in all varie- ties, and lias never been observed in white rat tinea rabbits, dogs, or other animals in which cancer occurs. There- fore, there is no reason to worry because one member of your family has suffered from cancer. It does no1 at all follow that any other member of the family will have it. In a family the members of which tend to be very long-lived, more cases of cancer will occur than in one in which the members die young, but this is not because can err is hereditary. Cancer Attacks the Healthy. — CTnfortunately, cancer attacks not only those who are in feeble health, but also, and with equal frequency, those who are strong ami healthy ami h. never suffered from any other disease. For tin- reason, it is especially important that such healthy people Bhould consult a physician if any sudden change in their well-being tak place, and particularly if there is any digestive disturbance or disorder of the bowels, for the stomach and intestines are fre- quent sites of cancer. AVe see, therefore, the unfortunate circumstances that while the improvement in conditions of living has prolonged the lite of the community on an average of ten years in the last cen- tury, the same condition has apparently increased the number of cases of cancer, since there are more people who reach the cancer age than formerly. This gives more cases of cancer in the population as a whole, though the relative proportion per age group may not be increased. How Cancer Begins. — While, as has been Baid, we do not know the cause of cancer, we do know a g 1 deal about how it occurs and what is apt to precede it. For instance, cancer frequently begins in moles or warts which are irritated by the clothes or are made to bleed and are kept Bore by repeated injury of any sort. Such warts and moles are perfectly harm- less at first, and become dangerous only after thej have been irritated in this way tor a long time, especially if the person is of the cancer age, that is, above forty-five yeai It 1- \\ 416 APPENDIX C therefore, to have such moles removed if they are in a situation where they are liable to be rubbed or injured. It has been found, also, that cancer frequently develops in the scar of an old burn, or in places where there is a chronic ulcer, as on the lip or tongue or leg, and care should be taken to see that such ulcers are healed as quickly as possible. Ulcers on the tongue and cheek frequently follow scratching from a poor filling or from the sharp point of a decayed tooth, and a dentist should be consulted if such an ulcer does not heal within a few days, so that the filling may be properly replaced or the point of the tooth hied off. Smokers should be particularly careful about any sore on the lip or tongue ; these are commonly found in those who use a pipe or cigars and smoke so that the tissue is burned by the hot stem of the pipe or at the point where the hot cigar smoke strikes, thus keeping up a chronic irritation. For this reason, cancer of the lip and tongue, while very common in men, is almost never seen in women. The beginning of an internal cancer is much more difficult to determine, because small tumors just as they start cannot be discovered except by accident ; but it has been found that they almost always begin in some injury ; for instance, ulcer of the stomach is a common cause of cancer, since the ulcers turn into cancers if they are not cured by proper medical or surgical treatment. So, too, cancers of the lower bowel are frequently preceded by chronic inflammation, and persons suffering from chronic dysentery, ulceration of the bowel, or bleeding piles, should consult a physician to see that these troubles are cured promptly and do not develop into cancer. Cancer of the breast in women frequently follows chronic inflammation, and is not caused by a blow, as is frequently thought. Any woman who notices a lump in the breast should at once consult a physician. It is very much better to be told that the thing is harmless and need not be removed, than to wait too long, only to find that it has already developed into a cancer. CANCEL' 417 Nature of Cancer. — Cancel is a \.t\ curious di • which is due to the running awaj of certain parts of the bodj tissue, that is, a few cells in the breast or in the liver or in anj other organ grow beyond the natural limit and invade the Burroundi tissues; then we have a cancer. This cancer often d • cot give any notice of its presence until a 1 < • 1 1 .^r time r the trouble has started, because the cells composing it are the Bame (or nearly the same) as the cells from which they Btarted, and, therefore, the body dot-s nol recognize the Eacl thai a cancer is growing until it becomes of considerable Bize. It Btarts very quietly, is very small at first, but gradually grows and destn the very tissues that 1'rrd it, until ultimately it kills its fa by injuring some important part of the body. I'-nt it is, in such a case, the cells of the body itself which are the parasifr in other words, there is no parasite introduced from the outside to cause the cancer. • Kinds of Cancers. — There are many kinds of cancer, and each kind acts differently and spreads in it > own way through the body. Certain forms which arise in glands, such as the breast, are called carcinoma, and this sort spreads slowly t«» places where there are small nodules of tis>ue>. called lymph nodes, in which the cancer collects, forming there Beoondary lumps or metastases, as the physician calls them. The true carcinoma does not often get into the blood vessels, and there- fore it remains localized for a very considerable time, bo that the surgeon has an opportunity to remove it, it' the diagnoc is made. Another kind of cancer, called by physicians •<-', spreads to the blood vessels and consequently is much ni' difficult to cure, because this spreading takes place v. i\ early in the course of the disease and the cells arc BWepf all 0\ er the body, starting new little tumors where fchej are deposited. While cancer grows through the very t: which surround it, it does not have roots, as the quacks Bay. W hat are called roots are more frequently blond vessels leading from the oan- cer, or bits of fibrous tissue; so that when a quaes 418 APPENDIX C patient that he takes a cancer out " by the roots," he is talking nonsense. Some cancers grow very slowly ; for instance, some of those on the skin may remain for ten or twenty years without spreading any very great distance and without forming little lumps elsewhere in the body. Other cancers grow very rap- idly and are fatal within a few months. Most cancers, however, remain local for a considerable period, probably six months to two years, before they really start to spread out in the tissues and if only they can be discovered and cut out during an early stage, the patient can be surely cured. Symptoms of Cancer. ■ — Unfortunately, the very smallest cancers give no symptoms unless they are on the skin or lip or tongue or elsewhere on the surface of the body ; and in these situations the earliest diagnosis can be made. Cancers the size of a pea or but little larger are often diagnosed and removed by a surgeon with an assured result, if the operation has been properly done. In the stomach and internal organs, however, the cancer does not give rise to symptoms until it is quite large, and it is important, therefore, for anyone who has any disturbance of the stomach or intestines, loss of weight, or anemia, to go at once to a surgeon, because by modern chemical methods and by the use of the X-ray a diagnosis can often be made on one of these cancers long before it can be felt or seen. One of the last symptoms of cancer is pain ; this is due to the pressure on the nerves by the growth spreading out through the tissues. When a cancer gives a great deal of pain it is usually beyond operation. Bleeding is a common result of cancer of the intestines, and is one of the most important symptoms. Every one should know, however, that when a lump appears anywhere on the body, a physician should be seen immediately ; the lump may prove to be an abscess or some- thing quite harmless, for there are a good many tumors which are quite harmless, or it may prove to be a cancer, and then if it has been seen early enough, it can be cured by operation. CAM EH \\\\ Occurrence of Cancer. - It has been Bhown l»v the Btudv of a large number of cases of cancer in various countries, thai the disease afflicts chiefly those of middle age, thai is, from fori five to sixty-five years. Younger people and tho r eighty years are rarely afflicted with cancer, excepl thai in very old people various mild cancel's of the skin are no1 infrequent; these, however, are easily cured by the X-ray or radium, and do not need operation in all cases. Women about the age of forty-five to fifty-five Bhould b< careful, if any lump appears in the breast, to have a careful examination made. Men of aboul this age, also, should be watchful of ulcers on the lip, tongue, or inside of the che< especially if the teeth are not good, and should have any Buch ulcers immediately examined by a physician. The physician may have to cut out a small piece and send it to a laboratory in order to determine whether or not the growth is cancerous, if it is too small to diagnose otherwise. It is very much betl to have a diagnosis made early than to wait until the doctoi sure that the thing is a cancer, for it is then often beyond operation. Treatment of Cancer. — The proper treatmenl of cancer i^ the removal of the growth as early as possible, it being re- membered always that cancer is a local disease when it begins and as a rule spreads through the tissues only after a consid- erable time. The removal of small cancers or of beginning cancers is often an easy matter and can be done under cocaine. Internal cancers, of course, can be removed only by an exten- sive operation; but the methods now are so successful thai a very large proportion of the eases can be saved it operation done early. There is a popular impression thai cancer is incurable. This is not so. Early operation cures Borne kinds of can. for instance those of the lip, in about 96 per cut of the casi - operated upon. If cancer of breast also could he operated upon at an early stage, nearly tour fifths of the cases would remain well. When operated upon at a late Btage, onlj one fifth 420 APPENDIX C the cases are cured, that is, show no further appearance of the tumor. Eadium and X-rays are very good treatment for the small cancers which appear on the faces of old people, and in some cases may be very useful in helping to complete the surgical cure by healing any small lump which appears after operation. They are also the best treatment for a cancer which has gone so far that it cannot be operated upon, and in such a condition may frequently be of such benefit that the patient may live a couple of years in comfort, but as a rule they do not cure can- cer, and they should, therefore, never be used on a cancer of any size ; instead, such a tumor should always be operated upon. Great care should be taken in selecting a physician to give the treatment with X-rays or radium, because only a few per- sons have enough radium for proper treatment, and only a few doctors know how Jo administer without burning the patient seriously, the large quantities of X-rays which are necessary to produce good effects. It is better that a patient should go to a hospital and get suitable treatment there, rather than to let his local physician experiment. The use of salve and other forms of treatment which are widely advertised in the newspapers are worse than useless. They often stimulate the cancers and make them grow more rapidly ; or if they do eat off the top of the growth, they leave the bottom spreading in deeply, and what is worse, result in a waste of time, for the tumor should be operated upon promptly. Xo form of internal medicine will cure a cancer ; that we know absolutely. Xor will any fluid injected under the skin cure a cancer. Cases of cures by such means which are re- ported in the papers or are talked about are merely instances of mistaken diagnosis, for the quack relies upon the ignorance of people as to what a cancer is and what it is not. Any small lump is called a cancer by the quack ; then if it disappears he will say he has cured it. As a matter of fact, a great many CANCER l_'l tests have been made of Hit- <;i m««t cures which are Bold in this country, and none of them have been found to be of the slight- est value in the treatment of real cancer, and real cancer is the thing in which people arc deeply interested, because through it their lives are in danger. [NDEX U> /< r< net s art to /"■•■ Abdomen, of crayfish . . . . 86 of grasshopper 13 Abnormal growth of tissue cause of disease .... 233 Abomasum. division of Btom- ach of sheep (ti^.) .... 154 Absorption, of food, defined 17.'! of food not nourishment . l T ~» Absorption in leaves of Ve- nus's fly-trap 39] Abstainers' record in -walk- ing- match (fig.) .... 224 Acid secreted by roothairs . . 269 Acid medium in stomach . . 171 Aconite, a poison 221 source of 327 Acorn, a dry fruit (fig.) . . . 309 Actinozoa, example of ... <> Active bacteria reduced in number by heating milk Ml Adam's apple 193 Adaptation, defined .... 161 student report on 162 Adaptations, of birds . . . . 138 of reptiles 1 •">! Adductor muscles of clam (figO • • • 95 Adulteration of foods . . . 180 Adventitious roots . . . . 284 experiments to show . . . . 404 Aerial roots, of corn .... 280 of ivy (fig.) 284 Aerial stems 286 Afferent fibers 213 Agar-agar, formula .... 346 plates (fig.) • • 348,349,360,351 Agave, section of epidermis (fig-) 8« Age of trees, how *.ld Agencies of seed distribu- tion 312 Agriculture, amount and kind of cultivation in as an industry influence of mi civilization . Air. home of bacteria . ... 344 Air cells of lung Airspaces in stems, function of Albumen, examples of . . . 176 Alcohol, ambitioD destroyed b a narcotic 221 ;i poison 221 and disease 243 and patent medicines .... canst- (if disease chemical composit ion "f . . I7»'i effect of. on circulation .... <>n digestion 182 formed by yeast plant . . . in bread driven off by beat , . Protozoa and vliorteii~. life 221 use of in consumption Alcoholism a disease ... Ale. manufacture of Alfalfa, member "f pulse famil rooi (fig.) Algae, aquatic plants example of 7 lark ..I conduct!] tern in . number of 7 Alimentary canal, of fp (fig.) 117. of man (ti- | 161 Alkaline medium in mouth . 171 Alligator < l i ^ - > nest 1 INDEX References are to pages Alligators, classified .... 7 described 133 example of reptiles .... 129 Alternate leaves, of beech family 327 of nightshade family .... 331 of parsley family 329 of pulse family 329 of rose family 328 of walnut family 327 Alternation of generations, in coelenterates 68 in ferns 372 in mosses 366 Althaea, member of mallow family 329 Altricial birds, defined . . . 142 nest of yellow warbler (fig.) . 142 American elm, scientific name of ^ . . 7 Ammonia in test for protein 265 Ammonium tartrate in Pas- teur solution 356 Amoeba, classified 6 described 47 diagram of (fig.) 48 microphotograph of (fig.) . . 47 reproducing by fission (fig.) . 49 reproduction of 3 respiration of 49 Amphibians, described ... 113 economic importance of . . . 127 example of 7 laboratory study of .... 113 number of 7 summary of 127 Amphioxus, notochord of . . 104 Anatomy of starfish (fig.) . . 72 Anesthetic, defined .... 221 dissolves lipoid 223 Angiosperms, classes of . . . 7 defined 7 Animal biology 11 Animal cell (fig.) 4 Animal parasites, habits of . 233 Animal starch, in liver . . . 174 Animals, agents in distribution of seeds 313 decomposed by bacteria . . . 345 without a backbone .... 6 Annelida, a class of worms . . 76 Annual rings, age of tree told by 377 in longitudinal sections of trunks 291 in stem of pine 377 Anopheles, mosquito (fig.) . . 42 cause of malaria . . . .42, 238 Antennae of grasshopper . . 14 Anterior adductor muscle of clam 95 Antheridia of fern 371 of moss 365 Antheridial plant of mar- chantia (fig.) 365 Anthers, described 296 Anti-pain medicines .... 246 Antitoxin, defined 351 described 252 in preventing spread of disease 246 use of in diphtheria .... 253 Ants, example of complete met- amorphosis 19 social life of 41 Anus, in digestive system of man 169 Aorta, largest artery in man . 202 Aortic arches of earth-worm 82 Aphis, woolly (fig.) 25 Apiary, escape of bees from . . 35 model (fig.) 38 Appendicitis 168 Appendix, vermiform .... 168 X-ray photograph of (fig.) . . 169 Appetite, guide to amount of food 180 Apples, a form of fruit . . . 310 example of pome (fig.) . 309, 310 produced by rose family . . . 329 value of as food 178 Aqueous humor 216 Arachnids, list of 91 Arbor vitae, cones of (fig.) . . 378 Arch, of foot 187 of hypocotyl of bean .... 264 Archegonia, of fern .... 371 of moss 365 Archegonial plant of mar- chantia (fig.) 365 Arctic regions, adaptations for 161 plants of 396 INDEX Reft r> run i Arctic regions, continued plants of , modifications of . . 397 use of lichens in 361 Arm, superficial lymphatics <>f (fig.) 304 Arms, example of organ ... B of starfish "_' Army worm, harmful insect 28 Arsenic, a poison 232 Arteries, function of . . . L97, 201 in circulation of clam .... (.»7 of crayfish 90 of fishes 109 word explained 86 Arthropods. Bummary of . . 93 Artificial respiration . . . . VX> Aseptic, defined 347 Asexual reproduction, of amoeba 3 of coelenterates <><> Ash, result of chemical change . 9 Ash twig (fig.) 289 Asparagus beetles .... 26 Assaults and drink (fig.) . . 222 Assimilation, defined .... 2 in plants 279 Aster, a common weed .... 3.'i4 Atmosphere, composition of , '-1 Auditory organ of grasshop- per 16 Auricles of heart 201 B Bacillus, a form of bacteria . . 343 Bacillus tuberculosis, cause of consumption 235 Bacteria, action on lava . . . 4 and mold from bouse tly (fig.) ■ 251 carried by insects 315 cause of sour bread . . . • 179 classified 1 conditions necessary forgrowth 344 decomposition of materials by ■ '>}! discussed distributed by (lies ;;*7 art to /""/■ Bacteria, continut 7 Balancing organ. .;ir a ■ . 218 Balaam, adventitious roots on i"i Balsams, conifers Bananas, value of M fond 17s Barberry leaves i tiir i ... Bark, function of Barley, n cereal (figO ■ • • • ;t monocotj ledon .... member of the grass family 0D6 Of the tirst plants culti- vated source of liquors .... Barnacles, economic Impor- tance of (fig.) "i. i"1 Baseball, advantage of M i nt- eise INDEX References are to pages Bass, a bony fish 106 example of fish 6 Bat, enemy of mosquito ... 42 hibernating (fig-) 151 Beaks of birds, variations in . 137 Bean, an irregular flower . . . 302 distribution of 318 early cultivation in America . 317 embryo, growth of 264 example of dicotyledons ... 7 field (fig.) 317 flower (fig.) 296 foodstuffs in 265 fruit of (fig.) 307 germination of (fig) .... 264 leaf, cross section of (fig) • . 273 pistil (fig.) 297 plant (fig.) 259, 267 injured by bacteria (fig.) . . 315 reasons for studying . . . 259 raising of 316 root, central cylinder of (fig.) . 268 cortex of (fig.) 268 epidermis of (fig.) .... 268 sections of (fig.) 268 showing tubercles (fig) • • 270 seed, laboratory study of . . 261 parts of (fig.) 260 relation to flower .... 297 seedling, parts of 267 stamen (fig.) 297 stem, laboratory study of . . 272 summary of 320 Bean and pea, photographs of (fig.) 260 Bean blight 315 Bean family, members of . . 318 Bean -weevil, larvae of . . . 316 work of 315 Beans as food 178 cheapness of, compared with meat 317 digestible • . . 317 for hogs or sheep 316 value of 317 Beans damaged by -weevils (fig.) 315 Bee farms, escape of bees from 35 Bee fly, a beneficial insect . . 41 Beech, value of Beech family, description of . Beech leaves, and buds of (fig-) Beechnut, a dry fruit (fig.) . . Beef, value of, as food .... Beef extract, in agar-agar . . Beef jelly exposed, in sanitary dairy (fig.) in unsanitary dairy (fig.) . . Beer, manufacture of ... . use of yeast in making . . . Bees, capturing a swarm of (fig.) classes of classified insecta clustering at swarming time (fig-) complete metamorphosis of . . cutting comb from hive (fig.) . drone gathering of nectar by . . . honey, value of imperfect female (worker) . . members of Hymenoptera . . nurses perfect female (queen) . . . swarming wax, value of Beet, a dicotyledon roots of (fig.) storage of food in Beetle, May, a harmful insect . potato, a harmful insect . . . Beetles, classified example of complete metamor- phosis field study of Belladonna, compared with stramonium source of Berries, produced by rose family Berry, a form of fruit .... collection of drupes .... defined illustration of (fig.) .... pepo, special kind of ... . Bichloride of mercury, use of Bilabiate flowers of mint . . Bile, a digestive juice .... Biological diseases, kinds of . 327 327 327 309 178 346 350 351 355 354 37 f 35 6 36 19 39 35 297 39 35 20 36 35 37 39 263 283 283 26 26 20 19 12 331 331 329 308 310 310 310 311 253 331 172 233 i \ Di:\ Referenc* a ><>■■ to pa Biology, defined 1 of disease 232 Birch roots, photograph ol (fig.) 392 Bird house, plan for (fig.) . . lis Birds, characteristics of . . . L36 classified 7 economic importance of . . . Ill number of 7 summary of 149 Birds' feet, different kinds of (rig.) 139 Bitter, a fundamental taste . . 165 Bittern, beak of 137 nest of 14'J Bivalves, reason for name . . 98 Blackberry, in plant succession 4(H) receptacle of fruit eaten . . Blackbirds, food of 31, 310 14.") 132 207 294 257 197 Black snake, a constrictor . Bladder Blade of bean leaf . . . of leaf, food storage in . . Blind persons, number of . Blood, corpuscles .... of man 197 plasma 197 student report on '200 vessels, function of .... :'. Bluebird, a beneficial bird . . 144 destroyed by hawks .... 145 destroyer of Lepidopt era . . 31 food of '-"J Blue jay, at bread crumb sta- tion 14S at suet station 148 at whole grain station . . . 14'.i feeds on larva; of Lepidqptera 31 Blue racer, a constrictor . . . 132 Boa-constrictor 132 Boards of health 246 Bobolink, female (tig.) ... 1 16 food of 11" migratory habits of . . . 143 nesting habits of in Body, parts of I Body cavity of earthworm . 81 Body temperature, of birds . 138 of mammals 150 of man 190 Bone, microphotograpb of (flg.) Bt rucl ure of ( t\g i Bony fishes, list of Borax, a preservative .... Borers, harmful beetles . . . eaten by downy \\ oodpecker Boric acid, a preservative Botfly, harmful Insect .... Bottling-, good and bad (fig I Bougainvillea hydroid [fig Bracket fung-i, ctT.-ct on trees Bracket fung-us (tiur) . . . . Brain, conl rol (fig.) efficiency, discussion of . . . conditions Decessarj for . . microphotograpb of ( fig > " Brain " of earthworm . . Braincase Bran, used as an adulterant . . Branch, example of organ Branch infected with mis- tletoe (fig.) Bread, crumbs for feeding station mold ( fig. ) laboratory study of . . . rye, \ alue of as food .... use of yeast in making wheat , value id as food . Bread-making, scientific Ka^is of temporary by-products of . . Breathing, in grasshopper . . in man not respiration Breathing center in develop- ing embryo Brewing, scientific basis of . . Bronchus Brook trout ( i'il: > raised in hatcheries .... Brown bat (fig.) Brown creeper, at bread crumb Btat ion at suet stat ion 1 1 of Brown hydra Browntuil moths Bryophytes clussitlod . , Bubbles of oxygen in masses of spirogyra 106 111 11 218 212 - ■ lis IIS . U * i 17s • 17s 11 l'.'l 22 1 ll Hi 111 152 lis lis 111 I •JO 6 INDEX References are to pages Bubonic plague, a bacterial disease 2.34 Bud, in reproduction of yeast plant 356 Budding1 (fig.) 287 Budding- cells of yeast . . . 356 Buds, a characteristic of stems . 286 Buffalo (fig.) 158 Bugs, members of Hemiptera . 20 Bullfrog 123 Bullhead (fig.) 105 organs of smell in 109 Bull snake, with hen's egg in mouth (fig.) 130 after swallowing egg (fig) . • 130 Bull thistle (fig.) 396 Bumble bee, carrier of pollen for red clover 304 economic value of 35 Burbank's work . . . .306,402 Burdock, common weed . . . 334 distribution of seed .... 312 by animals 313 in blossom (fig.) 311 Bur reed, a fruit distributed by water 314 Bushman, environment of . . 127 Butcher bird, food of . . . 22, 26 Butter, example of fat .... 176 flavor of, due to bacteria . . 349 indirect product of plants . . 401 value of as food 178 Buttercup, characteristic mem- ber of crowfoot family . . 327 study of pollination of . . . 305 Butterflies, classified . . . . 6, 20 complete metamorphosis of . 19 Butterfly, swallowtail, from celery worm 34 larvae of 28 pollinating Persian lilacs (fig.) 299 Buzzards, food of 147 C Cabbage, member of mustard family 328 plant (fig.) 292 Cabbages, laboratory study of 404 storage of food in 294 value of as food 178 Cactus, giant (fig.) 395 Calcareous skeleton of coral 69 Calcium, a chemical element . 9 Calcium phosphate, in Pasteur solution 356 Calla lily (fig.) 403 Calorie, defined 177 Calyx, described 296 Cambium, change to xylem . . 287 change to phloem 287 Cambium layer in woody stems 287 Camel, economic importance of (fig.) 154, 158 Canada ginger, storage of food in (fig.) . ... \ ... 291 Canada thistle (fig.) .... 336 Canal, alimentary, of frog (fig.) 163 of man (fig.) 165 Cancer, quacks and 244 Cane sugar in Pasteur solu- tion 356 Canine teeth 167 Canker worms 28 Canning of beans 317 Cap fungi (fig.) 357 Capillaries, described (fig.) . . 202 Capillarity 276 Capillary circulation (fig.) . 198 Capsule, a form of fruit (fig.) . 308 dehiscent fruit 310 fruit of lily 327 of moss 364 Capsule containing eggs of earthworm 83 Caraway, member of parsley family 329 Carbohydrates, a class of food 169 stored by bean 265 Carbolic acid, a disinfectant . 253 a poison 221 Carbon dioxide, a waste prod- uct of respiration . . . . 3, 9 formed by yeast plant . . . 355 how obtained by water plants 394 product of respiration only . . 276 taken from the air by plants . 401 Carbonic acid gas, formed by oxidation 9 Cardiac valve of stomach . 168 INDEX Carnivorous plants, modifica- tions of 389 Carpellate cone of pine . . .".7'.' Carrier of disease 243 Carrion beetle, beneficial insert 26 Carrot, membei of parsley family 329 storage of food in L's:; wild, pollinated by fly (fig.) . '_)(.»s Cartilage (fig.) 186 in skeleton 184 rings in air passages .... 193 where found 183 Casein, a form of protein . . . 1 T« i Catalpa, wind-distributed plant (rig.) 312 Catalpa twig- (fig.) 289 Caterpillars, destructive in- sects 28 larvae of butterflies .... 19 stage in metamorphosis . . 17-19 Catfish (fig.) 105 Catkin-like flowers of wal- nut 327 Catnip, a medicine 331 Cat-tails (tig.) 394 Cattle, escape inspection . . . 243 value of to man 154 Caudal fin of crayfish ... 87 Caudal region of lisli . . . 1«>7 Caustic potash in Fehling's solution 265 Cecropia moth (fig.) .... :*> Cedar, a conifer 383 Cedar bird feeding- young dig-) ;;- Celery, plant (fig.) 292 storage of food in 293 value of as food 178 Cell, animal (fig.) 4 name given by Hboke . . • 15 of plenroeoccus 339 plant (rig) I unit of structure 4 wall . . Cells, various forms of, in human body (fig.) 189 Centipedes (fig.) 92 Central axis of pine cone . . 379 Central cavity of sponge . . 68 ,tr- tO /""/■ Central cylinder of root (fig.) Central nervous system of frog (fig.) 118 Central pith of wood Central stalk of fern frond Cephalopoda, classified . - . Cephalopods, group of mol- lu^k^ Cere Cereal foods. Bouroe of . . . Cereals < fig.) list of Cerebellum, of amphibians . . of child Cerebral ganglion of mollusk Cerebral hemisphere of frog Cerebrum of man Certified milk, defined . . . Chameleon, a li/;ird .... Chara. food of craj fish . . . Cheese, example of protein . flavor of indirect product of plants . . value of as food Cheese skipper Chemical change, defined . . Chemical compounds . . . Chemical elements, propor- tion of iu li\ iug tliin_'- | fig. i Chemicals, used to enrich soil . Chemical terms, explanation of - Chemical test for carbon dioxide 275 Chest cavity of man . . 194, 201 Chestnut. :i dr> fruit (fig.) . . trees, value of Cherry, distribution of Beads of twigs (fig.) Chickadee. ;it hemp and millet station n^ at BUel stati.'ti 148 at w hole grain station destroyer ol md lai oi Lepidoptera I food of i>> Chimney swifts, u- -t . . . Ill u [ngs and feet of" China, dependence on rice . . ni too 119 224 119 131 101 178 11 271 8 INDEX References are to pages Chinese silkworm Chipping- sparrow, useful bird food of Chloride of lime Chloroform, example of anes- thetic action on lipoid Chlorophyll, in leaves of bean of pleurococcus Chloroplasts, containers of chlorophyll Choroid, coat of eye (fig.) . . Chrysanthemums, perfect blooms of ....... . Cicada, adult and nymph (fig.) description of member of Hemiptera . . . Cigarette smoking", effect of . Cilia, in air passage of paramoecium of sperms of moss, use of . . Ciliata, classified Ciliated larva, of liver fluke . Circular muscles, of earth- worm Circulation, effect of alcohol on in plants of mollusks organs of (fig.) Civilization, advanced by agri- culture Clam, digestive tube of (fig.) embryo of (fig.) example of mollusk . . . . laboratory study of .... right shell of (fig.) showing foot (fig.) soft-shell (fig.) Clams, artificial raising of . . edible example of pelecypoda . . . fresh water growing on oyster (fig.) . . . Clasping base, of corn leaf . . of grass leaves Classification, basis of, in Pro- tozoa of birds ... \ ..... . of plants by Linnaeus .... 28 144 31 253 221 223 272 339 272 216 226 25 25 24 227 195 50 366 6 77 80 205 278 97 199 326 95 97 6,94 96 95 94 100 100 100 6 94 101 281 323 52 139 303 of Classification, continued of seeds of living things .... Clean milk (fig.) . . . Cleft grafting"(fig.) . . Cleistogamous flowers violet (fig.) Clematis, twining petiole (fig.) use of petioles in Climbing plants, thigmotro- pism in Climbing stems compared with trees Clitellum of earthworm . . Cloaca of frog Clothing, obtained from mallow family source of Clover, affected by darkness member of pulse (bean) family 317, Club moss, related to ferns . . sporangium of (fig.) .... spores of (fig.) uses of Coal, formation of study of, in connection with ferns Coating of hairs, use to Arctic plants Coats of pollen grain . . . Cob, relation to corn grains . . Cobra, most deadly snake . . Cocaine, a poison cause of disease Coccus, a form of bacteria . . Cockroaches, family of Or- thoptera harmful insects Cocoanut, a fruit distributed by water Cocoon, of cecropia (fig.) . • of codling moth . . . . . . Cod, classified example of bony fish .... value of, as food Codfish Codling moth, a harmful Lepi- doptera (fig.) 19 complete metamorphosis of 263 6 348 286 301 292 294 287 286 83 116 329 401 393 318 369 373 373 374 374 369 397 299 309 132 232 232 343 20 22 314 30 18 6 106 178 178 ,28 17 INDEX 9 Codling moth, contintu d description of •"•'_' destroyed by downy w 1- peckei ill larva (rig.) 17 pupa (fig.) L8 Cce^enterates, examples of . . 63 described <'..'. Coelome of earthworm . . . M Coffee, effect on ln-art .... -^i, Cold, a common disease . . 197 Cold-blooded animals . . . 109 Cold storage, purpose of . . :;); Coleoptera, examples of . . . 20 Collar of corn leaf 281 Colonial Protozoa . , . . . 58 Colony, hydroids .... 66, <>7 Color of fungi, reason for . . 354 Colors, use of, in (lowers . 304, 389 Columbine, flower of (fig.) 304, 328 Use of .' 327 Communicable diseases . . 233 deaths from (fig.) 234 prevention of 239 Comparative cost of digesti- ble nutrients 17s Comparison of monocotyledo- qous plants with dicotj ledo- ikius 29B of pleurococcus and spyTOgyra 341 of unicellular plants with mul- ticellular 338 Complete flower, definition of 297 also perfect : -it- Complete metamorphosis of insects 17. 19 Complex flowers of higher plants W3 Complexion, light, 'lark . . . 190 Complex systems of higher plants 103 Composite Family .... 334 Compound leaves, detineil . . 294 Condor 136 Conducting tissue of pteris stem 370 Cones of pine (fig.) . 377, :;7->, .".7'.» Conifers ( fig.) ;:To general characteristics . • • 376 are t<< pages Conifers, continued related forms of summary "f Conjugation of spirok'y (fig.) Consumption, treatment of Contact, movemenl caused bj Contractile vacuole of amoeba Coon ( fig.) Cooper h Hawk. > eonomii i tils of Copperhead snake .... Copper sulphate, in Fehling's solution Coral islands, formation of . Coral reefs Corals, example of « kBlent example of Ad Inozoa Core, in pome fruits .... Coriander, member of parsley family Corn, anionni produced In ' canned, \ alue of as f ood . distribution of emln-yo leaves of example ol moi tj ledon , flower, described flower w 1th pist ils I fig.) . . . fruit of ( ti u: ) germination of (fig.) .... indehiscenl fruits ... kernels filled by corn smut ■ , laboratory Btud] of .... leaf, description of meal, value of as f 1 member of grass family . . . one of first plants cultivated . plant . prop roots of (1 plants, rootlet-, of i i'il: > . . . product Ion, map of .... raisin- as an IndUStTJ • . Importance of •• seed," comparison w ith bean -red. diagram (1 .... seedling smut . a parasite on corn . . a fungus spores of i fig.) .... Mem (fig. I 341 II". •; 310 I 178 0 7 310 281 178 318 10 INDEX References are to pages 215, Corn, continued summary of ... . wind-pollinated flower Cornea of eye (fig.) Corolla, described Corpuscles, red and white . . Cortex of root (fig.) . . 267, Cortical layer of kidney . . . of root Cotton, member of mallow fam- iiy production, map of . . . . seed of (fig) source of clothing Cottony cushion scale . . . Cotyledon of corn Cotyledons, affected in bean blight of bean importance of as food . . . size of storage of food in ... . parts of seed Cover crop, use of clover for . Cow, example of mammal . . stomach of Cowbirds (fig.) nesting habits of Cowpox, Jenner and .... Coxa, part of grasshopper's leg Coyote (fig.) Crab, soft-shelled (fig.) . . . Crabs, classified common name for crayfish . . economic importance of . . . example of Crustacea . . . Cranium Crayfish (fig.) appendages of 86 bearing eggs (fig.) circulatory system of ... . digestive system of .... example of Crustacea .... food and food-getting .... green glands of laboratory study of .... life history of limited environment of . . • . nervous system of organs of (fig.) 321 305 216 296 197 268 207 267 329 332 313 401 27 263 315 260 261 261 261 301 270 7 154 147 142 251 16 150 91 6 86 90 6 118 87 ,87 86 90 89 6 89 90 88 87 162 90 89 Crayfish, continued respiration of 90 typical crustacean 86 Creeping- disk of snails ... 98 Creeping- stem, of trailing ar- butus (fig.) 288 of Canada ginger (fig.) . . . 291 Crenate margins of mint leaves 331 Cricket, member of Orthoptera 20 hai'mful insect 22 Crocodiles, distribution of . . 133 example of reptiles 129 Crop of earthworm .... 81 Cross-fertilization, changes produced by 311 Cross-pollination, advantage of 305 320 7 147 148 effect upon wild plants . . Crow, example of birds . . Crows, as scavengers . at bread crumb station . . at suet station 148 at whole grain station . . . 149 food of 22, 27, 31 in nest (fig.) 146 Crowfoot family, biting juice of 328 characteristics of 327 members cultivated for orna- ment 327 products of 327 Crustacea, classified .... 86 economic importance of . . . 90 Crustacea and related forms 86 Cryptogams, classified ... 7 defined 6 Cuckoos, food of .... 27, 31 Cucumber, example of pepo . 310 Cucumber tree (fig.) .... 379 Cud, stomach of animals that chew the 154 Culex (mosquito) 42 •eggs and larvae of (fig.) ... 42 Culture, for protozoa .... 49 from clean milk (fig.) . . . 252 from dirty milk (fig.) . . . 252 of bacteria 244 Culture plates of agar-agar . 346 Curdling of milk, cause of . . 348 INDEX 1 1 /,■. t, r, net 0 an to pa . Curd of milk 265 Deer, :i end cbewer l.M Cure of plant disease . . . 320 Cures of quacks . . . . •_' II Curing- of meat, purpose . . 347 Currant, example of berry . . 310 Currant worms, caterpillars . 19 Cuticle of paramcecium . . 60 Cuts, treatmenl of 204 Cuttlefish, a cephalopod . . . 99 compared with squid . . . 100 Cutworms, harmful inseel . . 28 Cyclops, a small crustacean (fig.) 91 Cypress trees, conifers . . . 383 Cypris !U Cytoplasm, of pleurococcus 339 of amoeba 48 of nerve cells 209, 225 of protoplasm D Daddy-long-legs (fig.) . . . 92 Dahlia roots (fig.) 285 Dairy cow, model (rig ) . . . '-'17 Dairy cows, number and dis- tribution of (fig.) .... 249 Dairy stable, model (tig ) . . 248 Daisy, a common weed . . . '■•'■'A a composite 334 white (fig.) 334 Dandelion, a common weed (fig.) 334 a composite 334 distribution of seed (fig.) . • 312 Daphnia 91 Darkness, a universal stimulus :'>'.'.'< effect of, on clover and ozalis 393 Darwin on cross-pollination Davenport, quoted Dead matter simplified by bacteria 345 Deaf. Dumber of 257 Death caused by insects . ■ . 21 Deaths from communicable diseases (fig.) 234 Decay, caused by bacteria ■ . ;;'i Deciduous leaves, defined . 294 Decomposition caused by bacteria -U4 305 256 l.v. 1 310 310 Must ration «>i .volution . . . 154 Virginia, faw as of (fig ■ . 156 Deer-mouse .i nocturnal ro- dent i fig.) . . .... Definitions of common bio- logical terms Dehiscent fruits defined , . forms of (tig-) Deliquescent stems .... Denuded hills, cause ol freshets Deodorizers not disinfectants Department of Agriculture of United States, Inspect- ing meal .... in\ est i-'.i' iona concerning cot tony cushion scale . . Dependence, of fm of mistletoe of plants Dermis, defined Dero (fig.) M Desert plants, living condi- tions Deserts, habitat of plants Development of amphibians 120 Development of tadpole, two stages In I ii-'. > . . Devil fish, example ot cephalo- poda Dew. use by Bpermsof mosses . Diamond-shaped markings of marchantia Diaphragm, of man (fij 194, 195 characteristic of mammals . l"-41 passage Of OeSOphagUS llir.>iiL;li 167 Diastase, enzyi >f fermenta- tion Dicotyledons, group of plants represented by bean, squash, etc seeds of Diet IT" Digestion. ;i life proceed . • completed In intestine • . • described »71 effect of alcohol on IK2 in leaves of Venue's flj -trap laboratory stud] of .... 173 123 12 INDEX References are to pages Digestion, continued of food by pleuroeoccus . . . of food in seed Digestive fluids, of man . . . of starfish Digestive organs, of crayfish of man, summary of . . 161, Digestive system of animals, student report on .... Digestive tube of clam (fig.) Dill, member of parsley family . Dioecious flower, defined . . Diphtheria (germ disease) . 197, antitoxin 197, thirty years of in N. Y. state (fig-) treatment of Diptera (order of insects) . . described Direct heating (fig.) .... Dirty barns, milk from . . . Dirty milk, bacteria in (fig.) . Disease, cause of of beans (bean blight) . . . of plants, necessity for know- ing 320, of respiratory tract .... results of student report on summary of Diseases caused by abnormal growth of tissues .... caused by bacteria .... by plants or animals . . . by poisons, list of .... Disinfectants Disinfection Disk, central, of starfish . . . sucking, of starfish .... Disk-flowers of composites . Dissected leaves of crowfoot family Distribution of plants .... of plant products, an industry of seeds, agencies for .... of seeds by animals .... by pappus and hooks . . . by water from milkweed (fig.) . . . necessity for 339 266 171 72 89 182 164 95 329 299 234 252 242 252 20 41 197 348 319 232 315 402 197 254 256 258 233 401 233 232 253 253 71 73 334 328 399 401 312 313 389 313 313 311 Dividing cells of pleurococ- cus Dividing egg, becoming tadpole (fig.) of frog (fig.) Division of labor in man in sponge in volvox Dodder, twining stem of (fig.) . Dog, skeleton of (fig.) .... Dogtooth violet, stems of . . Dorsal blood vessel of earth- worm Dorsal surface of earthworm Dough in bread making . . Douglas fir. economic value of Downy woodpecker, a perma- nent resident food of Dragon flies, enemies of mos- quito member of Odonata .... Dredging, necessity of . . . Drills, a method of planting . . Drink, impairment of scholar- ship by (fig.) skill and endurance impaired oy (fig.) Drink and assaults (fig.) . . Drones (bees) Drowning, a form of suffocation Drupes, defined Dry beans, ability of to grow . Dry fruits, bean an example of Drying, protection of bacteria from Drying fruit, purpose of . . . Dry season, effect of on annual ring Dry seasons, effect of, on size of cells . . Ducks, feet of E 339 122 122 56 164 57 56 288 150 285 82 80 179 385 141 144 42 20 387 402 221 219 222 35 196 310 264 310 345 347 290 Eagle, a scavenger claws of ... head of (fig.) . . wings of . . . 378 137 147 137 140 136 ixi)i:x 13 Rqfen run b Ear, affected only by Bound . . 21 1 balancing organ 218 membrane of froj; Ill of grasshopper 11 pistillate flower of corn . . . 298 plan of (fig.) 218 sense organ 216 wax in L'ls Earthworm, economic impor- tance of 84 example of worms 6 excretions of 83 front end of nervous system of (fig.) 82 illustration of true worms . . 80 laboratory study of .... 82 life history of 8.'5 locomotion of 80 limited environment of . . . 1<»'- organs of (fig.) 81 respiration of 8ii ventral surface 80 Easter lily (tig.) 300 pollination of 307 X-ray of (fig.) 327 Echinoderms classified . . 6 Economic importance of am- phibians 127 of birds 114 of coelenterates "<> of crustaceans 90 of earthworms 84 of fern group 374 of gymnosperms 384 of lichens 361 of mammals 164 of mollusks I'*" of paramoecium 61 of plants 320 of starfish group 74 Economic insects 20 Economic interest in plants . 4 page* ■ Edible clams, nam. •«, ..f . . . L0Q Edible mollusks. Hal ..f . . . L00 Edible pulp of cherry, factor in .list rihiit ion Eels, migrations of 1 1'» Efferent fibers 213 Efficiency centers of brain 224,220 Egg, a reproducl i\ <• cell ... i white of, example of protein Egg-capsule of grasshopper (fig.) IS Egg cell (female parent) . . . fertilization ..f. in plants . . 300 Vblvoi (fig.) 06 Egg-plant, a I i plant ..f night- Bhade family Eggs, of frog (fig.), develop- ing 121, 122 of grasshopper (fig.) .... L0 of ladybug (fig.) 26 of Land-locked salmon (fig. ) .110 of moss plant 363 Egyptians, use of beans by , . -;1T Elbow, normal and broken, X-ray photograph (fig.) • ■ 180 Elk (fig.) 150 Elm. leaf (fig.) twig (fig.) 289 Embryo, corn, position of • • growth of, in o\ ulr .... ■"■"! heart of Of clam (fig. ) . 91 of coral of Liver flake "" parts of :;"i Bac, content a of vigorous, result of cross-polli- nation 300 Employment afforded by plant industries . . . . »oi Enamel, effeel of bacteria on 167 Encystment of amoeba . . . Endoderm, of root of sponge Endoplasm 18 Endosperm, food supply of corn of corn uraiu of coin, used for growth oi dling 14 INDEX References are to pages Endurance and skill im- paired by drink (fig.) . . Enemies, of the bean .... of corn of lepidoptera of man Energy, source of, in man . . yielded by bean English sparrow, attracts other birds destroys weevils eats larvae of Lepidoptera . . permanent resident .... scientific name of English walnut, protein in . . Enlarged base of onions, stor- age of food in Enriching the soil by nitro- gen Environment, denned .... discussed illustrated by development of frog Enzyme, of gastric juice . . . of yeast plant secreted by bacteria .... Ephemeridae, an order of insects Epidemics, of diseases, costli- ness of sore throat (fig.) Epidermal tissue of pteris stem Epidermis, of agave, section of (fig.) of bean root (fig.) of leaf (fig.) 272, of root of rootlets of xerophytes, character of . . outer layer of skin Epiglottis Epileptics, number of ... . Epiphytes, definition of . . . habitat of Epithelium, ciliated (fig.) . . columnar (fig.) flat (fig.) Eskimo, surroundings of . . . Esophagus, of crayfish . . , 219 315 316 30 316 1 317 148 27 31 141 7 170 294 318 10 126 125 172 354 345 20 255 243 370 396 268 274 267 269 396 189 193 257 399 399 189 189 189 127 89 Esophagus, continued of earthworm 81 of frog 116 of man 167 Ether, an anesthetic .... 221 test for oil 266 Eustachian tube (fig. ) . . . 218 of frog 114 of man 166 Evaporation, prevention of, in experiment 295 Evaporation of perspiration, effect of 190 Evergreen, leaves defined . . 294 trees, examples of 286 Evergreens, characteristics of 376 Evolution, theory of .... 123 Examples of plant societies 393 Excitable temperament, heart tracing 228 Excretion, a life process ... 2 definition of ...... . 3 in crayfish 90 of hydra 65 of man 206 of mollusks 97 Excurrent stem of ever- greens 286, 377 Exercise, benefits of .... 195 necessary to keep one fit . . 240 value of 204 Exercising, out of doors . .' . 194 to keep well 351 Exhalent pores 58 Exhalent siphon of clam . . 94 Exoskeleton, of crayfish . . 88 of grasshopper 15 of lobster, molted (fig.) ... 87 Experiment, to show produc- tion of carbonic acid in plants 275 performed on plants .... 403 Expiration, defined 194 Explosion of fruit case to scatter seeds 312 Extinct animals, remains of . 125 Extinct plants, remains of . . 125 Eye, section of 216 Eyeball 215 Eyelid 215 Eyes, of fish 109 INDEX 15 /.'•/• n nee* Eyes, continued of frog lit of grasshopper 11 of man, care of 217 of Nereis .si of vertebrates 215 F Faeces, removal of 17." Fainting-, cause of 208 Fangs of rattlesnake . . . 233 Fats, absorption of 174 furnished by animals .... 17" nutrients 1 Fawns of Virginia deer (fig.) 166 Feathers, a characteristic of birds 136 of birds, modifications of skin 190 Feeble-minded, number of . , 257 Feelers, of bullhead .... 109 of grasshopper 14 Feet of birds, different kinds of (tig.) 139 Fehling's solution, formula . 265 test for sugar 266 Female bobolink (fig.) .... 14"> grasshopper (rig.) 11 strobilus of pine .">7(.» Femur, broken (fig.) . ... 187 of grasshopper L6 Fennel, member of parsley family :v_,(.i Fermentation, cause of . . . 350 effect of 345 produced by enzymes .... 345 tubes (tig.) 355 Fern, forked veins of (fig) . • 371 garnet ophyte -;7l life history (fig.) . . . .371,372 Fern group, plants belonging to 373 Ferns, example of pterido- phytes 7 field study of 373 habitat of •"'<'•,., laboratory study of .... 373 Ferns and their Allies . . . .".o'.i in relation to water .... 375 summary of 375 Fertilization, defined . . . 68, '-"•>'., are to pagt * Fertilization, continued "i egg ••ell in the o\ iii.- . . , of frog Fertilized egg cell, beginning of new organism of volvox Fertilizers, use of, to supply elements Fibers in blood Fibrinogen, in format ion of clot Fibrous roots, of buttercup (fig.) of corn of grasses Fibrovascular bundles, cells of in leaves in root structure of use of, in photosynl bests Field study, of f.-rn^ . . . . of gymnosperms of insects Field suggestions, mammals . Filaments, described .... Finches, beak of Fin rays Fins, of ftah use of, in balancing and steer- ing Fires, forests destroyed by . . l>iv\ .niion of, by national g eminent Fire slash (fig.) Fire train in the Adiron- dacks (fig.) Fireweed in plant bu< ssion Firewood, furnished by b family Fireworks, ose of spores ol club iiio>s in Firs, conifers Fish, care of young skeleton of I fig. I mi in ma rv of Fish hatcheries Fishes, bony circul.it ion of classified 121 271 a . i i^n 12 137 107 1"7 107 100 112 112 lb) 106 109 8 16 INDEX References are to pages Fishes, continued food-taking 108 reproduction of 109 respiration of 108 scales of (fig.) 107 special senses /)f 109 with lungs 106 Fish fry, young (fig.) .... Ill showing volk sac (fig.) Ill Fission, a form of cell division 49, 339 Flaccid cells 273 Flagellata, group of Protozoa . 53 Flagellate protozoa (fig.) . . 52 Flat worms, classified . . 6, 70 Flavor, improvement of . . . 311 of butter 345,349 Flavors caused by fermentation 345 by bacteria 345 Flax, family 329 requires cultivation .... 329 useless parts of plant removed by bacteria 345 Fleas, member of Siphonaptera 20 Flesh-eating animals . . . 161 Fleshy fruits 309 Fleshy stalks for storage . . 294 Fleshy stems for food storage . 285 Flies, carriers of bacteria . . 347 classified 6 members of Diptera .... 20 Flipper of seal 152 Floods, cause of 385 damage caused by 386 prevention of 385 Florida alligator (fig.) ... 133 Flour, food elements in . . . 179 Flower, of Columbine (fig.) . . 304 of corn with pistils (fig.) . . 299 of mallow (fig.) 331 of mint (fig.) 303 of sweet pea (fig.) 298 violet, cleistogamous (fig.) . . 301 Flower bud 289 Flowering plants 323 common families 323 summary of 336 Flowering sage, adaptations for insect pollination . . . 304 Flowerless plants, classifica- tion of 7 food Flowers, field and laboratory study of of bean, organs wind-pollinated . . . Flycatcher, great-crested of Flycatchers, eaters of larvae . food of Flying squirrel (fig.) .... Fly pollinating wild carrot (fig-) Foliage, rank-scented leaves of nightshade family .... Food, a vital condition . . . care of definition of first plants to be cultivated for, list of for reindeer in Arctics . . 361 fungi a source of necessary to keep one fit . . of animals, student report on . of bacteria of clam of plants, study of of snakes of starfish — how taken . . . pecuniary value of storage — Canada ginger (fig.) stored in cotyledons of bean . Food-getting by animals . . by grasshopper Foods Foodstuffs in bean .... Food-taking of earthworm . . of starfish Food vacuole Foot of moss sporophyte . . Foraminifera, one of the (fig.) Forest fires, harming of soil by Forest reserves . . Forestry in Europe Forests, extent of in U importance of . . patrolling .... proportion necessary tall trunks of pine in Forked veins of fern (fig.) Formaldehyde, a preservative gas 302 260 305 26 31 145 152 298 334 314 240 169 326 , 366 354 240 171 344 96 320 132 73 177 291 261 2 14 1 265 84 73 48 366 52 387 387 387 385 385 387 385 377 371 348 253 i.\i)i:.\ Refert net b Formalin, in milk 180 used as disinfectant .... 'J.V. Fossils, described 124 shells of animals qow extinct (fig.) 124 Foul breath caused by bac- teria KIT Foxes (fig.) 151 Fox sparrows, transients . . 141 Fox terrier, comparison of primitive horse with . . . 154 Freezing1, protection of bacteria from 345 Fresh air, a condition for health 240 aid in curing consumption . . •_'■">•; Freshets, cause of 386 Fresh-water planarians . . 7(i Frog", bull, development of . . L23 central nervous system of (fig.) 118 common (fig.) 114 description of 113,114 eggs (tigs.) 120, 121 example of amphibians ... 7 enemies of 115 food of 115 green, development of . . . 123 habitat of 114 internal structure of .... 115 laboratory study of . . .114, 120 leopard, description of ... Ill organs of (fig.) 11<>, 117 reproduction of 117 respiration of 115 tree (fig.) 126 Fronds of pteris 370 Fruit, buds of cherry (fig.) . . 289 defined 308 of apple (fig.) 309 of beau (fig.) -;i|7 of bean and corn 308 of corn (fig.) 307 of pine of poppy (fig.) ■"■"* production in connection with storage roots 283 steps in de\ elopmenl of . . • 308 Fruits, distributed by animals • tig.) 311 by wind (fig.) 312 distributers of seeds . . . . 311 by are to pagt Fruits, tontinvu furnish luxuries of food • new varieties produced cross-pollination . of rose family w itli hooks (fig.) Fruits and seeds in- i . . . Fry. distribution of Fuel, hardwood 1 1 lurce of Fumigants Functions, definition of . . . Fundamental tissue of pteris stem Fung-i, action in changing lava 1" --oil classified 7 conditions favorable for growth summary of Fungus, an enemy of corn . . Furniture, lumber for .... Furs, as clothing ::il 401 .11 Ml 111 1 362 291 G Gall bladder of i !.>_' .... 117 Gall flies, example of ll\ menop- tera 20 Gametes, defined 341 of moss Gametophyte or sexual gen- eration of moss .... Gametophytes of moss . . Ganglia, of clam <>f earthworm Garden slug, shell of .... Garden vegetables, belonging to mustard family . to parslej family .... Garter snake, harmless Gas, a form of matter .... use in bread making .... Gastric gland (li-. i , . 169,171 Gastric juice 171 Gastric mill, of crayfish . . Gastropoda rlussinVd . . . Gtoese, feel "t 137 wild, t ransientfl l '1 Gelatinous secretion of earthworm 18 INDEX References are to pages Genera Plantarum, published by Linnaeus 303 Geometrid moth (rig.) ... 32 Geotropism, defined .... 284 Geranium, life processes of . . 259 simple leaf of 294 slip, roots of 284 study of flowers of 302 Germ, a name for unicellular organisms 343 diseases 233 Germination, laboratory study of 265 of corn (fig.) 277 Germs 233 a name for bacteria .... 343 in dust in houses 235 of disease carried by insects . 21 Giant cactus (fig.) 395 Gila monster, poisonous lizard (fig.) 131, 135 Gill, cover 107 Gill rakers 108 Gill scoop, of crayfish .... 90 Gill slits 104 Gills 107 of clam 96 of crayfish 90 Girdle, pectoral 105 pelvic 105 Gizzard of earthworm ... 81 Gland of starfish 72 Glandular hairs of sundew . 390 Glassy sponge, skeleton of . . 61 Glomerulus of kidney . . . 208 Gluten changed by heat . . 179 Glycerin formed by zymase 179 Glycogen, stored in liver . . 174 Gnats, eaten by birds .... 145 Goats, economic importance of 154 Golden rod, a common weed . 334 Goldfinch at hemp and millet station 148 Goldfish, a typical bony fish . 106 killed by tobacco smoke . . . 230 Gonium (fig.) 55 Gophers, harmful mammals . 155 Government inspection, of meat 78, 242 of oyster beds 102 Grafting, effect of 402 kinds of (figs.) .... 286, 287 Grain, differs from bean . . . 262 food for birds 149 of corn, a form of fruit . . . 310 Grains, large numbers of . . . 314 Grantia classified 6 described 58 Grape, example of berry . . . 310 Grapevine, wild, like liana . . 287 Grass family 323 compared with rose family . . 328 Grass, life processes of . . . 259 monocotyledon 263 wind-pollinated flower . . . 305 Grasses, flowers of 323 importance of, as food . . . 400 in plant succession 400 Grasshopper, classified ... 6 classification of 19 described 12 foot of 16 hairworm in body of (fig.) . . 79 injurious to corn plants . . . 316 laboratory study of ... . 13 laying eggs (fig.) 15 life history of 15 member of Orthoptera ... 20 mouth parts of (fig.) .... 14 parts of (fig.) ....... 13 representative animal ... 1.1 structure of 19 Gravity, influence of, on roots . 284 Gray squirrel (fig.) .... 151 Gray substance of nerves . 211 Great-crested flycatcher, food of 26 Great northern shrike, winter visitant 141 Grebe (fig.) 136 Greeks, use of beans by . 317 Green Algge 338 Green frogs, development of . 123 Green hydra, habitat of . . . 66 Green manure 270 Green manuring 318 Green turtles 131 Gristle, defined 184 Groove, on underside of starfish 73 Grosbeaks, beak of 137 INDEX 19 Ground birds, wind's «>f . . . 136 Grouse, a seed eater . . . . 117 at whole grain station . . . 1 19 Growth of bean embryo . . 264 Grubs, larvae of beetles . . . 19 of bean weevil - • l * > Guard cells, of fern Btomata 373 of stomal a 273 Gullet, of paramoecium . . . 50 Gulls, sailing birds 136 herring ( fig.) 137 Gums, effect of tartar on . . . fi.7 Guttation drops, defined . . -74 Gymnosperms, by-products of 384 classified 7 discussed 376 field study of 383 reason for name 381 student report on 383 use of 384 Gypsy moths, injurious insects 28 H Habitat, of evergreens .... 381 of mosses 364 of Protozoa 46 Habits of plants, of interest to fanner 402 Haemoglobin in corpuscles . . 197 Hair, origin of 190 Hair snakes 78, 79 Hair worm 7 s in body of grasshopper (fig.) . 79 Hairs on leaves of Venus's fly-trap "''.'1 Hairy woodpecker i fig.) . . H7 Halibut, value of as food . . . ITS Hand, superficial lymphatics ol (fig.) . • • •' 204 Hard palate 166 Hardwood, forests, described . 388 trees, large flowering plants . 323 Harmful bacteria 343 Harvest-man, harmless arach- nid 91 Hawk, Cooper's 148 example of bird 7 marsh 146 red-shouldered 148 are to /"'.'/■ Hawk, contin red-tailed sharp-shinned Hawks, beneficial birds ami claw s of Hawkweed, a common weed Hay infusion for protozoa Head, of fish ol grasshopper ol rat t lesnake book lug p< glands (fig.) . . of young eagle (fig.) Headache medicines Head end of earthworm . . Heads, inflon bc< nee of compos- ite family Head-thorax region of cray- fish Headwaters of rivers pro- tected Health Healthy bodies and bacteria Hearing- Heart (fig.) and lungs (fig.) center nuisi le ••■■Us t fig. i of craj fish valves of Heart and blood-vessel- man Heart-shaped body, prothal- lium oi fern Heat and pressure. Influence of in forming coal .... Heating1, common methods hot air (fig.) milk, eft. ct of on bacteria . . strain (fig.) protection of bacteria from . Hedge nettle iti-. > Heel of man ....... Hellebore, sourer of • • Helmholtz on alcohol . . . Helpful bacteria Hemiptera. discussed .... order of insects Hemlock, bark, use oi Colics Of (fig.) conifer 143 148 1 .7 • 19 13 l l l»<> Sii •: 218 201 22 1 190 197 187 10 20 INDEX References are to pages Hepatica, example of incom- plete flowers Heredity, discussed of disease Hermit crabs, economic impor- tance of Herons, beak of Herring, economic importance of Herring- gulls (fig.) .... Hibernation, defined .... study of Hickories, members of walnut family Hills, a method of planting . . Hilum of bean Hinge of clam Hinge ligament of clam . . . effect of starfish on .... Hinge teeth of clam . . . . Hip bones of man History, of bean plant .... of corn plant Hogs, fed on beans inspection of Hollow bones of birds . . . Hollow stem, of horsetail . . of parsley family Hollyhock, member of mallow family Home making, work of women Home study of moths and butterflies Honey, amount of carbohydrate in locust, seedlings of (fig.) . . made from nectar by bees . . value of in U. S Honeybee, discussed .... stages in development (fig.) worker, queen, drone (fig.) . . Honeybees clustering at swarming time (fig.) . . Hoofs of cattle, origin of . . Hooks, on fruit of burdock . . on seeds, use of Hookworm disease .... Hop lice destroyed by lady- bugs Hops, use of, in manufacturing of beer 302 125 255 91 137 106 137 115 159 327 402 260 96 96 73 96 187 317 320 316 243 138 374 331 329 257 33 170 281 297 39 34 35 34 36 190 313 389 239 26 355 Horehound, a medicine . . . 331 Horned pout (fig.) 105 Horned toad, a lizard (fig.) 129, 131 Horns of cattle, origin of . . 190 Horse, classified 7 discussed 153 evolution of 154 use of 155 Horse-chestnut, compound leaves of 294 seedlings (fig.) 281 twig of (fig.) 288 woody stem 287 Horse-radish, member of mus- tard family 328 Horsetail (fig.) 374 joints of stem 374 Horsetails, members of fern group 373 related to ferns 369 Host, defined ....... 31 of liver fluke 77 Hot air heating (fig.) . . . 195, 196 House flies, eaten by birds . . 145 Housefly (fig.) 41 bacterial growths from (fig.) . 250 bacteria and mold from (fig.) . 251 House sparrow, scientific name for 7 Houses, source of materials for 401 Human biology 161 Human stomach, X-ray photo- • graph of (fig.) 168 Humming birds, beak of . . 137 summer residents 141 Humor, aqueous 216 vitreous 216 Humus destroyed by fires . 387 Hydathodes, defined .... 274 Hydra, cell layers in (fig.) . . 65 diagram of (fig.) 64 example of coelenterate ... 6 laboratory study of ... . 66 microphotographs of (fig.) . . 63 microphotographs of body wall of ... 64 Hydra-like animals described 63 summary of 70 Hydras, examples of coelente- rates 63 ixi)i:x 21 /,' f{ rerun a Hydrastis, source of ... . 327 Hydrochloric acid in arti- ficial gastric juice . . . 173 Hydrogen, proportion of in plants and animals .... 8 Hydroid. bougainvillea (fig.) »>o' colony thai Looks like a plant (fig.) 67 medusa (fig.) . . » .7 obelia microphotograph of (fig.) 66 Hydroids, described .... <;<; examples of coelenterates . • 63 Hydrophytes, definition <>f . . 394 finely divided Leaves of sub- merged forms 394 waterlilies (rig.) 393 Hydrotropism, detined . . . 284 in roots 284 Hydrozoa, classified .... 6 Hymenoptera, discussed . . :'«l order of insects 20 Hyphae of bread mold . . . .V>7 Hypocotyl. pari of embryo . . •"•||i part to grow first 261 use of, to embryo 261 I Ice, a form of water .... 9 use of , in caring for milk . . .".is Ice cream, dangers from . . . 350 manufacture of 350 Ichneumon flies laying eggs in trees (fig.) W Ichneumons, discussed . . . 39 enemy of Lepidoptera . . . . 28 members of order Hymenop- tera .... 20 Imbecility 232 Immunity 26S denned 251 Immunization 'S<- Imperfect flower, kinds . . 302 of corn 298 Improvement of plants, methods of W2 Incisor teeth 166 Incomplete flower, part lack- ing in $•- /" pages Incomplete metamorphosis ol tree cricket (fig.) Indehiscent lr . Independence of plan Independent existence moss gametophyte . India, dependence "n i . Indian pipe Indians, use <>f beans bj . environment of . of Indigestion causes of tablets for Indirect heating (fig.) ■ . . Indistinct ring.left by bud scales produced by droughl .... Inefficiency, caused !>y tempo- re iv sickness Influence of alcohol on de- velopment of brain . . Infusoria Inlnilent pores Inhalent siphon of clam . . . Inhalers Inherited diseases .... Inner chamber of eye ui. Inner coat of pollen grain Inner ear (tig.) .... JIT, Inoculation Inorganic foods Inorganic matter Insanity 16 17 ••1 1.7 180 181 196 Insect, group, divisons of pollination \ Lsitors, Btudj of Insecta Insect enemies of bean plant Insects, acti\ [ties of . . . . carriers of bacteria . . . . de\ ices for attracting . . . . examples of Arthmpoda field study of life bistorj "i nhjeet iii \ isit tng tl"\\ en Inspection of meat Inspiration, defined Insulation of nerve ftbei Integument, development of bean of o\ ales M 172 10 \\i 12 194 301 • 22 INDEX References are to pages Intercellular spaces .... 274 Interdependence of plants . 361 Internal gills 122 lungs 122 structure of earthworms, labo- ratory study of 82 Interrelationship of animals 61 Intestine 168 Invertebrates 6, 103 Inverted image 217 Involuntary muscle cells (fig.) 189 Iodine test for starch . . . 265 Iris of eye (fig.) 216 Iron 9 Irregular corolla of saliva . 304 Irregular flower of violet . 302 Irregular flowers, denned . . 302 Irritability 2 Ivy, adventitious roots of . . . 404 aerial roots of (fig.) .... 284 Jack-in-the-Pulpit, storage of food in stem of 285 Jaw bones of fish 106 Jaw of man 166 Jellyfish, example of coelenter- ate 6 belonging to hydra group . . 63 Jenner, vaccination 251 Jewelweed, explosive fruit of . 312 Jimson weed, member of night- shade family 331 Juice of mustard family, characteristics of . . . . 328 Juice of the buttercup, char- acteristics of 328 Junco (fig.) 144 at hemp and millet station . 148 at suet station 148 Katydids, a family of Orthop- tera 20 Keel of bird's breastbone . . 138 Keeled sternum of bird . . 138 Kernel, comparison with bean pod 262 Kidney, section of (fig.) . . . 207 Kidneys of frog 117 King bird (fig.) 145 food of 145 Kingfisher, nesting habits of . 142 (fig.) 146 Koch, discoverer of Bacillus tu- berculosis 235 of tuberculosis test .... 349 study of bacteria by ... . 351 Laboratory experiments with leaves .... 275, 295 Laboratory study, of bacteria 346 of bean seed 261 of bread mold 360 of ferns 373 of foodstuffs in seeds .... 266 of grasshopper 13, 16 of gymnosperms ... . 384 of leaves for storage .... 404 of live fish 107 of moss 366 of moth and butterflies ... 33 of pleurococcus 339 of pollination of flowers . . . 305 of protozoa 50, 53 of reptiles 135 of roots 271, 285, 404 of seed dispersal 314 of seeds 263 of skeleton 188 of spirogyra 341 of sponge 59 of starfish 73 of stems 404 of tasting 166 of twigs 291 of wood 384 of worms 81 of yeast plant 356 Lacteals 174 Lactic acid, effect of ... . 348 Ladybug 26 eggs of (fig.) 26 Lady slipper (figs.) . . 303, 397 / VDEX 23 Lampreys Land-locked salmon, eggs <>i (fig.) 110 Land snail let Larch, a conifer Large cells, position of In an- nual ring 286 Large intestine 168 Lark, meadow ill Larkspur, medicinal plant . . 327 Larva, o I codling moth (fig.) . 17 of mourning cloak butterfly (fig.) • .' 28 Larvee. of bean weevil .... 316 of leaf miner in elm leaf (fig.) • ;,,1 Larynx 193 voice box (fig.) 194 Lateral bud 288 Lava, change to soil .... 100 Lead, cause of disease .... 232 Leaf, buds of cherry (fig.) . . 289 epidermis of (fig.) 274 of elm (fig.) •-".'! of oak (fig.) 294 scars, defined 289 skeleton (fig.) 273 Leaflets, of compound leaf . . '-"-'J of fern frond 373 Lean meat, example of protein 268 Leather 1 •"»."> indirect product of plants . . 401 Leaves, of bean 260 of ferns '• 369 of grass, shape of 398 of ivy, arrangement of . . . 398 of mosses 364 of pine, described 378 of pitcher plant (fig.) .... 390 of seed .• 260 of trees, arrangement of . • . 398 Leaves and bud of beech ( fig.) 327 Leech 76 Leeuwenhoek, improver of mi- //./. /■• no i ore to pagt i . . 106 in changing Hi »sci ipe :y>o Legs and wings of birds . • 136 Lens of eye (tig.) 216 Lenticels. described .... 287 Leopard frog ill Lepidoptera 20 Lianas, defined 2W Lichens, action lava to soil epiphj tic habit of field study of (fig.) •. . . . flection -•: ■ B1 Life history, ol tern it: ol grasshopper 15 of oyster, Btagea in • : _ . . 101 of the mosses i fig. i . . of the plant, defined . . .* Life processes it of bacteria Light, a universal stimulus . . a" vital condition Lilac, yellow swallowtail butter- th gathering oectai from (fig.) Lily family Lily-of-the-valley (fig.) . . . Linden twig (fig.) Linen, furnished by tfax fami Bource of clothing i"l use of bacteria ba manufactur- ing Lingual ribbon Linnseus, work of Lions Lipoid : Lips of frog 11"' Liver 117 Liver flukes 77 Liverworts 7 Lizards 131 horned toad, example of • I g 129 Lobes, olfactory .... .lis optic . . . ' 119 Lobster molted eX. .skeleton of I fig.) Lockjaw Locomotion Locust Loggerhead shrike (fig | Longitudinal muscles Long-spurred vude: - of sei D Lumber, from gymnosperms t r<'iu hardwood trees furnished bj walnut tan j ho* cut SO 24 INDEX References are to pages Lumbering, in New York (fig.) 380 operations, forests destroyed by 387 Lungs 3, 117, 192, 193 and heart (fig.) 193 Luxuries, fleshy fruits ... 311 of food from rose family . 328, 401 Lymph 203 Lymphatic circulation . . . 204 Lymphatics, superficial, of arm and hand (fig.) 204 M Mackerel, a bony fish .... 106 value of, as food . . . ." . 178 Maggots, larvae of flies ... 19 Magnesium, a salt 173 Magnesium sulphate in Pas- teur solution 356 Main arteries, of frog (fig.) . 202 of man (fig.) \ 203 Malaria 42, 237 caused by mosquito .... 238 protozoan disease 234 Malarial parasite, source of . 238 Malarial swamp (fig.) . . . 238 Mallard duck, skeleton of (fig.) 138 Mallow, family, importance of 329 flower of (fig.) 331 Malt, formation of 355 Mammals, classified .... 7 discussed 150 number of 7 report on 155 summary of 159 Man, example of mammal . . 7 Mandibles (fig.) .... 13, 14, 41 Mantle 94 Map, of corn production . . . 319 of cotton production .... 332 of potato production .... 335 of production of oats .... 324 of production of orchard fruits 330 of wheat production .... 325 Maple, seedlings, cotyledons of . 282 development of (fig.) . 279, 280 syrup 385 trees, products of 385 twig (fig.) , . 289 Maple sugar industry, in Ohio 385 in Vermont 385 Marchantia (fig.) 367 Marsh hawk, partly harmful . Martins, mosquitoes eaten by . Massasauge, a rattlesnake . . Masts, use of gymnosperms for Material for clothing . . . Matter, organic and inorganic 145 42 132 384 329 9,10 163 Maturity, a period of life May beetle, injurious insect (%•) • • • 26 May flies, member of order Ephemeridae 20 Meadow lark, food of . . . 147 nest of 141 Mealy bug (fig.) 25 Measles, probable cause of . .234 Measuring worms, cater- pillars 19 Meat 10 indirect product of plants . . 401 lean, use of, as food .... 176 Mechanical tissues of pteris stem 370 Median fins of fish 107 Medicinal members of crow- foot family, list of . . . 327 Medicines furnished by crowfoot family .... 327 Medulla, of frog 119 of man 224 Medullary layer of kidney . 207 Medullary rays, in woody stem 289 of pine 378 Medullary sheath of nerve . 211 Medusa, described 67 hydroid (fig.) ....... 67 pelagia (fig.) 67 Melons, example of pepo . . . 310 Mendel, Gregor, study of peas 125 Mendelian laws, defined . . 126 Menhaden, example of bony fish 106 Mental inefficiency, cause of poverty 257 Mercury poison . . . . 221,232 Mesentery of frog 117 Mesoglea of coelenterate . . 63 INDEX 25 Mesophyll of leaf 273 Mesophytes. ilfiiniiiuii .,1' . . 397 Mesothorax of grasshopper 16 Metal container dangerous for milk 300 Metamorphosis 16 complete 17 incomplete 16 Metathorax of grasshopper 16 Metazoa, defined 66 Method of pollination, basis of classification •"-<>•"> Meyer. Hans, discovery of . . 223 Mice, destroyed by hawks 145, 14<» harmful mammals 166 Microbes, a name for bacteria . 343 Microphotograph. of bone (fig.) L86 of brain (fig.) 212 of conjugating spirogyra (fig.) 341 of corn stem (fig.) 279 of hydra (fig.) o"'> of stomach (fig.) 170 of sun flower stem (fig.) . . . 286 Micropyle, of bean 261 use of 300 Microscope, inventor of . . . 350 Microscopic animals and plants 233 Middle ear (tig.) . . . . 217,218 Middle West, production of corn by 318 Midrib of marchantia . . . 367 Migration of birds .... 143 Milk, care of 350 card of , example of protein . 266 from healthy cow . Dumber of bacteria in 347, 348 good and bad hottlinu i t'iL,r.) . 362 indirect product of plants . . 101 value of, as food 178 Milk glands, characteristic of vertebrates 150 Milk teeth (fig.) 166 Milkweed, fruit (fig.) .... 312 plant distributing seeds (fig i 313 Milkweed butterfly .... Milt of fish Ill Mineral matter in food ... 1 Mineral substances .... 179 on to j"i'/' § Mink, harmful mammal . . . Mint, flower ol .... Mint family, charactei Mints used for medic ;d in food Mistletoe, absorbing orgaus ol a Bemi-parasite I branch infected \\ ith (rig.) . Mites, arachnids 91 parasitic Mixed diet of man .... 170 Model, dairj cow i fig, i . . . dairy stable (fig . , . 248 resen oir (fig.) . . . . . 'Jin Modified cotyledon (scutel- liu f corn Modified leaves, of club m.>-> of husks of corn of |><-;i plant (fig.) Moisture, a condition for growth of bacteria .... 34 \ a Bl imulus a vital condition 315 for lichen gathered by fungus , Molars of man 167 Mold, grown from water (fig I Molds, classified 7 Moles destroyed by hawkfl . \\'< Mollusca. classified number of MoUusks, characteristics of . . M life history of Bhells of, home of hermit crab 91 summary of 1"'-' Molt, defined 16 Molting, discussed Monarch butterfly (fig | 20 laboratory b( udy of .... Monkey, example of mammal . 7 Monocotyledons, group of flowering plants 7 represented bj com Beeds of . Monoecious flower, defined Of beech family .... of w alnnt famih Morning glory, a climbli plan! a dicotj ledon sc. (iiin--, of US 26 INDEX References are to pages Mosquitoes, breeding places . 41 members of Diptera .... 20 Moss, composition of cushion of 364 two generations of 366 Mosses, and their allies . . . 3(54 classified 7 general features 364 habitat 364 life history of (fig.) .... 3(55 number of 7 types of (fig.) 364 Moths, carriers of pollen . . . 304 example of Lepidoptera ... 20 Moths and butterflies, field study of 33 Motile cells (sperms) of moss plants 365 Motor function 213 Mourning" cloak butterfly (fig.) 29 Mourning- dove (fig.) .... 143 Mouth, cavity of earthworm . 81 of man 164 parts of grasshopper (fig.) . . 14 Movements of plants . . . 392 Mucus, use of, by clam ... 96 Mucous membrane .... 182 Muscle, bundle 188 Muscle cells, heart (fig.) . . 189 involuntary (fig.) 189 voluntary (fig.) 188 Muscles, color of 188 involuntary 188 of man . . , 184 of upper leg (fig.) 188 scars of clam 96 voluntary 188 Mushrooms, edible fungi . . 354 poisonous 233 Mustard, a common plant fam- ily ....... . .323 Mutton, value of, as food . . . Muzzling of dogs Mya arenaria, edible clam . . Myriapods, discussed .... Myrtle warbler, at suet station 328 178 250 100 92 148 N Nails, origin of 190 Narcotic, defined 221 Nasal cavity of fish .... 109 Nasturtium, twining petiole of (fig-) 292 use of petioles in 294 Natural gas, formation of . . 375 Natural laws, basis of success in agriculture 320 Nectar, relation to pollination by butterfly 30 sought by insects 297 use of, to flowers 389 Needle-like leaves of pine 377, 378 Nephridia of earthworm . . 83 Nereis, an annelid worm ... 84 Nerve cells (fig.) .... 209, 211 of mollusks 98 Nerve fibers, defined .... 209 description of 211 gray substance of 211 white substance of 211 work of 210 Nerve pathways in midbrain 119 Nerve trunk 222 Nerves, cranial, of frog ... 119 location of 119, 210 of earthworm 82 of frog 118 of mollusks 98 Nervous system, function of, in locomotion 2 growth of 211 of crayfish 90 of earthworm, front end of (fig-) 82 of frog (fig.) 118 of man (fig.) 209, 210 parts of 209 summary of 230 Nest, of bittern (fig.) .... 142 of chimney swift (,fig.) . . . 144 of yellow warbler (fig.) . . . 142 Nest-building of birds . . . 142 Net-veined leaf 272 Nighthawks, destroyers of mosquitoes 42 food of 145 Nightshade family, character- istics of 334 Nissl bodies 225 Nitric acid, test for protein . . 265 / \ DEX 27 i: /< !■■ run t Nitrogen, a chemical element gathered by bacteria . . . 270, 318 in lipoid 222 proportion of In living thin. '.• Node of corn stem .... 281 Nomenclature of plants by Linnseus 303 Non-motile cells (eggs) of moss plants 366 Non-productive persons, Dumber i>r 257 Non-smokers, scholarship of . 229 Normal body temperature of man 190 Nose. Bense organ 215 Notochord, embryonic struc- ture of fishes .... 103, 106 Nourishment, defined . . . 1T."» in beans 317 Nuclei of pollen and egg- (tiur.) 300 Nucleoli of cells .". Nucleus, of cell 268 of nerve cell 209 of pleurococcus 339 Nurses, care of bee larva.* by . :"><> Nuthatches, at snet station . 148 at hemp ami millet station . . I 1 ^ destroyers of Lepidopt era . . '.1 useful birds Ill Nutrients, defined 1 Nuts, from hardwood trees . . furnished by walnut family 327 indebiseent fruits 310 Nymphs of cicada (fig.) . . 25 O Oak, leaf (fig.) 294 trees 327 Oatmeal, value of as food . . 178 Oats, a cereal (fig.) 326 a monocotyledon map of production of . . . . 324 member of grass lamik . . . 326 value of as food 178 Obelia, classified 6 microphotograpb of (fig.) • • 86 Obnoxious plants, nanus of • Octopus, example of mollusk M member of cephalopoda ( liu'-i • '•''•, Odonata. order of . . Odor, use "( in flowers Odors, of other f Is absorbed by milk produced bj fermentation Oil, tests for Oils, a class of foods . . Old agre. a period in lift- li Olfactory lobes, function ..f of frog (fig.) One-celled plants . . . Onions, storage •■! food in Operculum of fish . . . Opium, a poison .... Optic lobes oi f p.- nij lis. Optic nerve di-. i . . . . 21<>, Oral side of starfish .... Oranges, a form of fruit . . . example of berry section "i | tii: ) value oi as i 1 Orbits, defined Orchard fruits, from I u- iiy mail of production of . Orchids, greenhouse epiphj pollinated by moths .... Org-an. defined pa it 1. 1' body Organic matter, example of Organism, beginning of Den Btudj "I Bensat ion in Org-ans, of bean ■ • of circulation (fig . . of cia\ lish of earthworm (fig. > . . . . of frog (figs.) 1 16, Of plants Org-an system, defined . part "f bod] Orioles, food of , • nest of ... . Orthoptera. order of Insect! Osmometer flg.) Osmosis, defined . bomemade apparatus for show - log .... in absorpt ion »1 i 1 in photos) uthcsit) l II . IP' in; 11'' JIT 310 213 \ 1" » M 117 t 1 142 28 INDEX References are to pages Osmosis, continued in root hairs 269 in sponges 58 Outer coat of pollen grain . 299 Outer ear (fig.) 217, 218 Outer skeleton, of crayfish . . 88 of turtle 130 Ovary, of coelenterates ... 68 of frog 118 part of pistil 297 Overwork, predisposes to tu- berculosis 240 Oviducts, of frog 118 of horned toad 131 Ovules, change to seed . . . 300 described 297 of pine 379 Owl, feet and beak of ... . 137 screech (fig.) 138 snowy, a winter visitant . . . 141 Oxidation, defined 1, 9 in birds 138 Oxygen, a chemical element . 8 a condition for the growth of bacteria 344 proportion of, in living things 8 use in respiration 3 use of, by birds 138 Oysters, artificial raising of . 100 barnacles and clams growing on (fig.) 101 destroyed by starfish .... 74 examples of mollusks .... 94 stages in life history of (fig.) . 101 value of, as food 178 Pain 213, 215, 232 Palate of man 166 Palisade cells of leaf .... 272 Panama Canal, a health prob- lem 239 Pancreas 169, 172 Pancreatic juice, enzymes in . 172 Pansy, capsule of 310 cleistogamous flower .... 302 Paper, made from spruce trees . 384 Papillae of tongue 165 Pappus, use of 389 Paraffin, in transpiration ex- periment 295 Parallel venation, of corn leaf 282 of leaves of lily family . . . 326 of grass leaves 323 Paramoecium 6 diagram of (fig.) 50 example of ciliata 6 mode of defense 51 reproducing by fission (fig.) . 51 resisting attack (fig.) .... 51 study of 50 Parasites, action of 233 group of fungi 354 ichneumons 30 liver fluke 77 plants, modifications of . . . 389 tapeworms 76 Thalessa 39 Parasitism, a dependent rela- tion 403 Parsley family, characteristics of 331 list of plants in ..... . 329 Parsnips, member of parsley family storage of food in Partridge, wings of .... Passer domesticus, scientific name of English sparrow . . Pasteur, discoverer of lactic acid bacteria study of bacteria by ... . Pasteurization, denned . . . Pasteurized milk tested for bacteria Pasteur solution, formula of . Patent medicines, defined . . to be avoided in consumption . Patrolling of forests .... Paupers, cost of supporting . . Pea plant, modified leaves of (fig.) member of bean family . . . seedlings of Peaches produced by rose family 329 Peach-tree borer 28 Peanut, peculiar habit of (fig.) . 318 Peanut shucks as adulterant 180 329 283 136 348 350 349 347 356 244 237 387 258 294 317 282 INDEX 29 Referenct a Pears, example of pome . . . 310 Pear scab (figs.) 359 Peas, Mendel's experiments <>n . 125 Pectoral girdle of vertebrates 105 Pedal ganglion of clam . . 96 Pelagia, a medusa (fig.) • • • 67 Pelvic girdle of vertebrates 106 Pelvis, of kidney 207 of trunk of in;iii 207 Penguins, use of wings . . . 136 Pennaria, classified ('» tiarella (fig.) 68 Pennyroyal, a medicine . . . 331 Peony, use of :f . 297 Perianth of lily family . . . 326 Pericardium, of clam .... 97 of man 201 Permanent teeth (fig.) . . . KIT Persian lilacs pollinated by swallowtail butterfly (ti v.) 299 Perspiration, amount of, how regulated L90 a waste product use of 190 Petals of bean flower . . _".»*; Petiole, length of 389 of bean leaf 272 of clematis (fig.) '_".»_' of nasturtium (fig. ) . . . . '_".i2 Petroleum, format i f. . . 375 Petunias, members of night- shade family 331 Phanerogams, a group of plants c, 7 Pharynx, of earthworm ... Bl of man 164, l»'»o Pheasant, a seed eater ... 1 17 wings of 1 •'••'» Phenolphthalein test for acid 21 M ' Phlegmatic temperament, heart tracing of (fig.) . . , Phloem, carrier of food . . • 271 conducting food materials • . '-"•',| constituent of green bark . 287 are to pagi Phloem, contintu d pi '-it ion in w I\ -t .-m . position of in \ ascnlar bundle Phaebes, destroyers "f Lepidop- tera Photosynthesis, finished prod- net of <-\ \ gen produced bj .... performed bj stem .... \ ital process In plants Phosphates 176, Phosphorus, a chemical ele- l menl found in li\ ing thing* a poison in lipoid 179 useful in body Phylum (Phyla i groups of plants and animals ... 7 Physical change described . Pieplant, storage <>i food in . . Pigment in skin Pigs, important mammals 151 Pike, a bony ti>h !<*; raised in hatcheries . . . . ill Pill bug (fig.) 9] Pine, example of gymnosperm . 7 pollen of (fig I 57 ripe cone of i fig. ) seed Of ( fig.) ataminate Bl robill of (fig.) t ree, described 77 parts of Pine grosbeak at hemp and millet station n* Pine siskin at hemp and millet station 148 Pinnae of fern frond .... Pinnately compound leaves of walnut family .... Pistil, described diagram of Pistillate flower, described of monoecious plant of willow (fig) Pitch, souree of . . . Pitcher plant leaves ol (fig use of leaves In Pith in corn stem .... Plague of locusts .... 30 INDEX References are to pages Planarian worm (fig.) . . 76, 77 Plant, biology ....... 259 cell (fig.) 4 conditions, change of ... . 400 ecology, definition of ... . 399 food, of interest to farmer . . 402 lice 41 injurious to corn plant . . 316 members of Hemiptera . . 24 on fern (fig.) 24 protected by ants .... 41 life, mystery of 404 peculiarities of 389 or animal matter food of bac- teria 344 poison 233 Plant-eating animals . . . 161 Plant societies 393 Plant succession 400 Plantation in the Adiron- dack^ (fig.) .... 385, 386 Planting- young- trees in the Adirondacks (fig.) .... 384 Plants as organisms, interest in 402 Plants decomposed by bac- teria 345 Plasma 203 Plecoptera, order of insects . 20 Pleurococcus, appearance of (fig-) 338 described 338 example of alga 7 group of cells 339 where found 338 Plum, example of drupe . . . 310 produced by rose family . . 329 Plumage, discussed .... 139 Plumule, connection with seed leaves 261 defined 260 part of embryo 301 Pneumonia 234 Pod of bean 260, 308 Poison, defined 221 in tobacco smoke 230 Poisonous character, of crow- foot family 327 of lizards — Gila monster (fig.) 135 of snakes 132 character, con- Poisonous tinned of toxins 345 of plants of nightshade family 331 Pollen, cell (male parent) . . 299 distributed by wind .... 305 of pine (fig.) 387 produced by stamens .... 297 sacs of pine 379 tube, formation of 300 of pine 381 Pollen grains growing through pistil (fig.) ... 300 Pollination, by wind .... 305 definition of 297 step in the production of fruit . 308 Pollution of -water .... 247 Polytrichum, laboratory study of 366 Pome, a fleshy fruit (fig.) . . 309 Pond scum, habitat of . . . 339 Pome fruits, defined .... 310 Poppy, capsule of 310 fruit of (fig.) ....... 308 Pores of sponge 58 Porifera, classified 6 Pork, inspection of 78 trichinella in 77 value of as food 178 Posterior adductor muscle of clam 95 Potassium, a chemical element found in living things ... 9 contained in food 173 Potassium permanganate, a disinfectant 253 Potassium phosphate, in Pas- teur solution 356 Potato, a food plant of the nightshade family .... 331 (fig.) 285 beetles, injurious insects . . 26 blight, a fungus 360 production, map of .... 335 response of, to light .... 393 value of, as food 178 Poultry, destroyed by certain hawks 145 Preecocial birds, defined . . 143 nest of bittern (fig.) .... 142 / VDEX 31 /,' /< r< nces Prairie dog's, harmful mam- mals 160 Prairies, suited to raising <>f corn 318 Praying- mantids, a family of Orthoptera Jit Predigested foods, use of . . 181 Pre-molar teeth, discussed . . 167 Preparation of foods, dis- cussed 177 Preservatives, list of . . . . 348 Preserved substances . . . 347 Preventable diseases . . . 234 Prevention, of communicable diseases '_'•">'. » of plant diseases 320 Primary root of bean . . . 267 Prisoners, number of ... . 257 Proboscis of butterfly . . . 29 Propolis, use of, by bees . . . 37 Prop roots of corn (fig.) 278, 280 Protective coloration. of birds 139 of grasshopper 14 of moth (fig.) 33 Proteid substances in flour. source of food for yeast plant 358 Protein, a class of foods . . . 169 in bean 317 product of photosynthesis . . 276 stored by beau *_'»i". Prothallium of fern, a gameto- pbyte 371 Prothorax of grasshopper . Hi Protonema of moss .... : 165 Protoplasm, of cell . . . . 5,208 of pollen grain :'><><) Protozoa, cause of disease . . 237 classified <"> flagellate (fig.) 52 number of kinds of .... •'. resemblance to bacteria . . . 343 simplest animals 15 Protozoa and alcohol . . . Protozoan cell, described . . 16 Protozoan culture .... 19 Psalterium, division of stomach of sheep (fig.) 154 Pseudopodium of amoeba 17 Pteridophytes, classified . • 7 an to pugi Pteris, described (t ... stein (fig.) Ptomaines, in Ice cream . . Public institution tion of servants for . . . 244 Puff ball, example of Coi (fig.) : Bpores of, " Bmoke " Puffins. nest of 142 Pulmonary tuberculosis, dis- cussed Pulse, caused i>\ beating ol heart Pulse, members of bean family, tnenl loned in Bible .... Pulse family, characterise of discussed foods furnished i>> li^t of plants of \ alue to soil of plants of . Pumpkin, example of pepo ■ . Pumpkin seed, a f i — 1 * (fig.) . . Pupa, a Btage in metamor- phosis of insects description of of cecropia i tiur.) of codling moth (fig.) . • • • Pure culture, defined .... Of J east Pure food laws Pure milk, cosl of producing Purple finch, at hemp and mil- let station 1 18 Purple sea urchin .71 Pyloric valve of stomach . . Python, a constrictor .... MX) 311 104 18 18 18 180 Q Quack defined .... . . :\\ Quail, a seed eater . . . 117 at w hole main -.tat ion 149 - — » — • Quarantine, defined •.'17 laws . violation of 2 17 Queen bee (fig.) .... d. 0 1 . . 32 INDEX References are to pages R Rabbits, destroyed by hawks . harmful animals young (fig.) Radial arrangement of star- fish Radish, a dicotyledon .... member of mustard family . . roots (fig.) storage of food in Range of plant's territory, how increased Rank-scented foliage of nightshade family . . . Raphe of beans Raptores, discussed .... Raspberry, in plant succession . canes killed by tree crickets . distribution of produced by rose family . . . Rattlesnake, a poisonous snake (fig.) discussed head of (fig) poison, effect of rattles of (fig.) Rats, destroyed by hawks . . harmful animals Raw materials of photosyn- thesis Raw milk, danger from . . . Ray flowers of composites . Rays of starfish Rectum, part of digestive system Red bud, member of pulse fam- iiy Red clover pollinated by bumble bee Red corpuscles of blood . 197, Redheaded woodpecker (fig.) Red poll, at hemp and millet station Red rust of wheat, a fungus . Red-shouldered hawk . . . Red-tailed hawk young of (fig.) Red- winged blackbird, food of 145 155 154 71 263 328 282 283 312 334 261 140 400 22 313 329 132 132 131 233 131 145 155 276 350 334 72 168 329 304 198 28 148 360 145 145 140 22 361 Reflex action, discussed . diagram (fig.) .... in the earthworm . . . in the frog in the hydra Reforestation .... Refrigeration of foods . Regeneration, defined Regular flowers, defined of mustard family . . . Reindeer, food of . . . useful animal Relationships of plants an interesting study . . . Remedies, plants a source of . Report on twigs Reproduction, a life process . asexual, defined of amoeba of bacteria of grasshopper of hydra of paramcecium of yeast plant simplest form of Reproductive bodies of pteris Reproductive glands of star- fish Reproductive hyphse of bread mold Reptiles, discussed life history of summary of Reptilia, classified number of Reservoir, model (fig.) . . . poor (fig.) Resin, source of Respiration, described . . . artificial, described . . . . in man organs of of amoeba of bean plant of grasshopper of hydra of mollusk of paramoecium of starfish 212 212 214 214 214 387 240 75 302 328 ,366 154 403 401 293 2 3 49 345 15 65 51 356 339 371 72 357 129 129 135 7 7 240 241 384 2 3 196 192 192 49 275 15 65 97 51 74 / \ DEX li< /■ n n& | an to pa Respiration, contimu <> produces carbonic acid gas . 276 studenl report <>n 192 Respiration, blood, and ex- cretion 192 Rest, effect of, in consumption , 236 necessity for, in keeping well . 240 Resting- stage (pupa) of cod- ling moth 19 Restricted diet of primitive life 170 Reticulum, division of stomach of sheep (fi^-) 164 Retina (fig.) 216 Rhizoids, of marchantia . . . 367 of mosses 364 Rhizomes 286 Rhizopoda, classified .... 6 Rhododendrons, insect visitors 34 Rhubarb (pieplant) storage of food in 293 Ribbed stems of parsley- family 331 Rib of leaf 272 Bice, amount produced in lr. S. member of grass family . . . use of, in China and India . . value of, as food Right shell of clam (tiur.) . . Rind of corn stem 281 Ring of cambium in woody stems 287 Ripe cone of pine (tiir-) . . . 378 Ripened ovary, the fruit of a plant 308 Robber bees 36 Robin, a useful bird Ill food of 27 often a winter resident (tig.) . 141 Rochelle salts in Fehling's solution 265 Rock oil, formation of . . • • 375 Rocks, habitat of Lichens . . . 360 habitat of pleurococcufl • • • Rod-shaped bacteria . . . 343 Romans, use of beans b\ . 317 Roots of ferns 369 of pine Rose, a common plant family . 328 compound Leaves of .... 294 326 3-_'i ; 326 178 95 Rose, continui d family, discussed .... foods furnished by ... KM Mow it t urning into a fruit I leaf, stipule-, ,d (fig.) . . stamens and pistil of Shrike (great northern), a win- ter visitant Ill loggerhead (tig.) 139 ill'i tO /nil/' s Shrimp.s, economic Importai of Sickness, student report on . Sieve vessels of phlotfm use of protozos of sponges (fig.) . . • "■'•. 'd Skill and endurance ii: >d by drink (fig.) Skin, as sense organ ... described . 216 diagram of (fig.) example i in of fruit Skunk, example of harmful mammal ( ti^.i . . Sleep, amount needed . . Sleeping sickness how »pn id probable cause of . . . Slimy feeling of spirot • Slimy substunc. | ipoo r< nio\ ed h\ b Blips producing roots '"1 36 INDEX References are to pages Slug- (garden) Slugs, examples of mollusks Small cells, position of in annual 99 94 290 116 168 251 250 234 14 Small intestine, of frog . . . of man Smallpox, Jenner and .... lessened by vaccination . . . probable cause of Smell, organ of, in grasshopper Smoke, result of chemical change 9 of puffball 364 Smoker's heart, how affected . 227 Smoking, charts showing effect of 228, 229 Smoking and scholarship . . 229 Smoking of meat, purpose of . 347 Snails, discussed 98 example of Gastropoda (fig.) 6, 98 examples of mollusks . . . . 6, 94 respiration in 99 shells (fig.) 99 tongue of (fig.) 98 Snakes, (black,) harmful . . . 132 discussed 131 examples of Reptilia ... 7, 129 food of 132 Sneezing, distribution of germs by 197 Snowy owl a winter visi- tant 141 Soda, a nutrient 176 preservative 348 Sodium carbonate in artifi- cial pancreatic juice . . 173 Sodium chloride, scientific name for common salt . . . 173 Soft palate of man .... 166 Soft-shelled clam, an edible mollusk (fig.) 100 discussed 100 Soft-shelled crab (fig.) ... 91 Soil, an element of success in agriculture 320 upper layers, habitat of bacteria 344 Soil bacteria (fig.) ...... 344 Soldiers, a class of ants ... 41 Soles of feet, animals that walk on 152 Solomon's seal, stems of . . 285 Song sparrow, at hemp and millet station 148 killed by hawks 145 useful bird 144 Sori, of ferns (figs.) . . . .370,371 Sorus, position of (fig.) . . . 372 section of (fig.) 372 Sounds from sound waves . 218 Sour, a fundamental taste . . 165 Source of man's food sup- ply 320 Sources of danger in milk . 349 Souring of milk, cause of . 348, 350 Sparrow, chipping, useful bird 144 English, chatter attracts other birds 148 example of bird 7 fox, example of transient bird 141 hawk, destroyer of grass- hoppers 22 destroyer of cicadas ... 26 Sparrows, seed-eaters .... 148 Spawn, migrations of fishes to 109 Spearmint, member of mint family 331 Special modifications of plants 389 Special senses, organs of . . 215 Species defined by Linnaeus 303 Specific names used by Lin- naeus 303 Sperm, a sexual cell 4 cells of fern 371 of moss plant 365 volvox 56 nucleus of pollen grains . . . 299 Spermaries of hydroids . . 68 Sphinx moth from tomato worm ........ 34 Spicules, described (fig.) ... 59 Spider, member of Arachnida (fig.) 91,92 Spinal column of man, curves of 187 Spinal cord, part of nervous system 119 Spines of echinoderms ... 71 Spiracles, location of ... . 16 of grasshopper ...... 15 / \ DEX Spiral arrangement of scales on cones 379 Spiral bands of chlorophyll in spirogyra 310 Spirillum, a form of bacterium 343 Spirogyra, example of algae 7. conjugating (fig.) 340 described 339 microphotograph of (fig.) . . 341 Spirog-yra and pleurococcus, summary of 342 Sponges, bath (fig.) .... 58 classified 6 clog water mains (>1 described .".7 economic importance of . . . r,i example of Porifera .... »i how gathered 61 how prepared 61 number of 6 parts of (fig.) 59 relation to other animals . . til reproduction structure of 58 summary of 62 two stages in development of (fig.) 60 use of bacteria in preparation of .'^.". where obtained <>1 Spongilla, reproduction of . . 60 Spongy layer of leaf .... 27:; tissue of velamens 399 Spleen, of frog 117 Splints, used in Betting bones 186 Spoiling of food by bacteria . 347 Sporangia, of pteris (fig.) . . .".71 Sporangium, of club moss (fig.) 373 Spores (tig.) 360 of bread mold 357 of (dub moss ( fig. ) 373 of corn smut (fig.) 362 of moss 364 Sporophyte, dependence of . . 366 generation of moss 366 Sprain, defined 186 Spraying solution, ingredients of 25 outfit (fig.) 21 Sprouting of grain to furnish malt 355 an to i ""/>'* Spruce, compared with pine • cample ol l:> mnosperm t iii'- source "i vrood pulp wood of (fig.) Sputum, destructi 1 m <\\ Bpread of t uberculo« Squarr -I'msof mint family Squash, a dicotyledon . . . example ol j »* - j *• • d (fig.) Squid, described example of ( lepbalopoda of niullnsk Squirrel, agents in plant dis- persal flying (fig.) gray (fig.) Stagnant pool, breeding place for mosquitoes Stalk of grain of corn . . . Stamen, diagram of . . . . Stamens and pistils of | (fig.) Staminate cones of pine . . Staminate flower of monoecious plants .... Ol willow ( tiur- ) Staminate strobili. ol pirn 77 Starch, a nutrient chemical composition of ■ form of carbohydrate .... in fermentation . . . in floor product "f photosj ni bests Starfish, anatomj ol (fig. I body "t". diagram .... classified described (fig.) • • familj group internal struct are of life bistorj of ... looomol ion of . . . . •-n miliary of ... State governments, pi tion ni fires bj Statistics of life Insurance companies . . Steam, a form of water i 311 152 151 11 1 17'' 71 71 71 38 INDEX References are to pages Steam heating (fig.) . . 195, 197 Steering", use of fins for . . . 107 Stegomyia, a mosquito ... 42 Stem, of bean 260 of corn (fig.) 280 of ferns 369 of mosses 364 of pteris (fig.) .... 369, 370 of xerophytes, green color of . 396 woody (fig.) 289 Sterile, defined 347 Sterile hairs, of moss plants . 365 Sterilized -water in tests for bacteria 347 Sternum, keeled, of birds . . 138 Sticklebacks, nests of ... . 112 Stigma, part of pistil .... 297 featbery 305 Stimulant, craving for ... 226 Stimuli, causing movement . . 392 list of 2 Stinging- cells of coelenterates 64 Sting of bee .' . 36 Stipe, of fern 373 Stipules, of pulse family . . . 329 of rose leaf (fig.) 331 Stomach, a digestive organ . . 2 example of organ 5 microphotograpb of ... . 170 of sbeep (fig.) 154 of starfish, use of in food- taking 73 pear-sbaped (fig.) 168 valves of 168 Stomach-intestine of earth- worm 81 Stomata, entrance of bacteria tbrougb 315 number of 274 in xeropbytes 396 of fern 373 of leaf 273 position of in waterlilies . 274, 394 size of 274 Stonefhes, members of Plecop- tera 20 Stone fruits, defined .... 310 Stone of drupe 310 Stones, inorganic matter ... 10 wet by spray habitat of mosses 364 Storage of food in leaves . . 293 Straight-veined leaves of beech family 327 Stramonium, a medicine, source of 331 Strawberry, description of . . 310 produced by rose family . . . 329 value of as food 178 Street cleaning by flushing, advantage of 235 String beans, canning of . . . 317 ovules in 309 value of as food 317 Strobili, of pine 379 staminate (fig.) 377 Structural changes due to alcohol 225 Structure of amoeba .... 47 of paramoeciurn 50 of roots 267 of woody stems 287 Struggle for existence, dis- cussed 314 modifications aiding in . . . 389 Student report, on sickness . 232 on skeletal structures . . . 187 on water supply 242 Studies about plants, kinds of 311 Study of lichens, field trip for 362 Study of plants as organisms . 320 Style, part of pistil 297 Success in cultivating plants 320 Sucking disks of starfish . . 73 Suction in photosynthesis . 276 Suet, for winter feeding of birds 148 station 148 Suet-eating birds 148 Suffocation discussed . . . 196 Sugar, a nutrient 1 broken up by yeast enzyme . 354 elements in 9 form of carbohydrate .... 265 in flour 179 obtained from maple trees . . 385 organic matter 10 product of photosynthesis . . 276 solution in study of spirogyra 341 source of 400 value of as food 178 INDEX Re/i n in-' $ Sugars formed in fermenta- tion 365 Sulphur, a disinfectant . . . 253 an elemenl in living things . . 9 in spraying solul Ion .... 25 Summary, of amphibians . . 127 arthropods 93 bacteria ."..".1 bean 320 birds 149 circulation jus con iters 388 corn 321 digestion of man l*'j disease 258 ferns and their allies .... 375 fish 112 flowering plants 336 fungi :;•;_' hydra-like animals 7<» insects 4.1 mammals 159 mollusks KL' mosses and their allies . . . 368 nervous system '_':!<> of our interest in plants . . . 40i protozoa 54 reptiles 135 simplest plants 339 skeleton of man l'.»<> spirogyra and pleurococcus . 342 sponges 62 starfish group 75 worm group 84 Summer residents, examples of ill Sundew, described 390 diagram of (rig.) ."-'.'1 photograph of (tig.) .... 390 rapid movements of . • . . 392 sticky substance on leaves . 390 use of leaves in 294 Sunflsh, care of eggs by . . . 112 example of bony tish (fig.) 104, 106 Sunflower, " seed " (I'm. ) . . 262 stem, microphotograpb of i fig.) 286 Superficial lymphatics of arm and hand (tie,.) . ■ . 204 Supply of oxygen kept up by plants I'd t<> pagy ' Surplus food stored in ro> ' Survival of the fitter Swallows, destroj insects Swallow-tail b>. pol- linating Persian til from celerj \\ orms la rvaa of Swamp, breeding place for i quitoes (fig.) Swarming of bees .... Sweat glands, location of . , number of work of Sweet, a fundamental taste . . Sweet pea. flower of (1 Swifts, destroyers of flying bi- sects Symbiosis, a dependent relation defined example of Symptoms, medicines in con- ned ion with 314 190 165 i « 361 61 245 Tachina fly. beneficial Insect Tadpole, development of from two stages in (fig.) .... respiration of by gills .... Btage of frog Tail region of flsh Talons, characteristic <»f birds of prey Tanning, use of hemlock hark in Tap root of bean Tapeworm, a common (fig.) classified Tar. source of Tarsus of grasshopper's foot Tartar, effect on gums .... Tassel, staminate flower ol corn Taste cells (fig.) Technical names of of flower Teeth, milk (fig.) • • ol man permanent (fig.) Telegraph poles, use of gyTOr oosperms for n 122 122 106 in 78 <■ 16 167 166 II I 167 •N| 40 INDEX References are to pages Temperament, excitable, heart tracings of (fig.) 228 phlegmatic, heart tracings of (fig.) 228 Temperate regions as a habitat 161 of evergreens 381 Temperature of birds 138 offish 109 of soil, an element of success in agriculture 320 Tendrils of pea plant (fig.) . . 291 response of to contact . . . 393 Tent caterpillar 28 Tentacles of hydra .... 64 Terminal bud 288 cones in relation to .... 379 Terrapin, use of as food . . . 131 Testa developed from in- tegument 301 Test for oxygen 8 Test for weevils 316 Tests for foodstuffs 265 in baking and brewing . . . 356 Thalamencephalon of frog . 120 Thalessa, larva of 40 Thallophytes, classified ... 7 Thallus of marchantia . . . 367 Thick stems for food stor- age 285 Thick- -walled cells of annual ring, how formed .... 290 Thigmotropism, defined . . 284 in climbing plants 287 in roots 284 Thin- walled cells, when formed 377 Thirty years of diphtheria in N. Y. State (fig.) .... 242 Thistle, a common weed . . . 334 Thoracic cavity 201 Thoracic duct 174 Thorax, of grasshopper ... 13 Thorn, modified leaf (fig.) . . 293 Thorns of rose (fig.) .... 329 Thousand-legged worms (fig.) 92, 93 Thread-like hairs, of spirilla and bacilli 343 Threads, of bread mold ... 357 of spirogyra . . . * . . . . 340 Throat, cavity of man . . 164, 166 of tadpole 122 Thyme, a member of mint family 331 16 43 91 155 30 153 263 331 34 Tibia, of grasshopper . . . Ticks, harmful insects . . . members of Araehnida . . Tigers, harmful animals . . Timbers of mines, use of gym- nosperms for 384 Tissue 4, 5 definition of 268 Toad, horned (fig.) 129 Toads, hibernation of .... 123 Toadstools, example of fungi . 7 Tobacco, aroma of, produced by bacteria 345 effects of use of 226 inhaling fumes 229 member of nightshade family . 331 Tobacco worm, bearing co- coons of parasite (fig) . . . Toes of cow, rudimentary . . Tomato, a dicotyledon . . . food plant of nightshade family worms, larvae of sphinx moth , Tongue, a sense organ (fig.) 165, 215 of man 164 of snail (fig.) 98 Toothache, result of poor teeth 167 Tortoise, use of as food ... 131 Touch, movement caused by . 392 skin, an organ of 215 Toxin, bacterial poison . . . 351 of diphtheria 252 secreted by bacteria .... 345 Trachea, of man 192 of grasshopper 15 Trailing arbutus, creeping stem of (fig.) Transformation of pupa of mourning cloak butterfly into adult (fig.) .... Transient birds, examples of Transpiration, defined . . devices for retarding . . . experiment to show . . . in full grown leaves . . . 288 29 141 274 397 295 291 INDEX 11 Trap-like device of Venus's fly-trap 39] Tree cricket, incomplete meta- morphosis <>| (fig.) ... 17 harm !ul insect 22 Tree frog (fig.) 126 Tree killed by bracket fun- gus (fig.) 369 Tree sparrow at bread crumb station Ms at suet station Ms Trees, habitat of lichens . . . 360 life processes of 259 Tremex borer, harmful insect • 40 Triangular flaps, mouth of clam «x; Trichina, discussed 77 Trichinella, discussed (fig.) . 77. 7^ Trichinosis, cause of ... . 7H Trichocysts of paramoecium 60 Tropical vegetation (fig.) . . 4< >1 Tropics, as a habitat .... 161 home of epiphytes 399 Trout, example of fish .... »i bony fish 106 True flowering plants . . . 323 Trunk region of flsh . . . . l Turnip, member of mustard family storage of food in 283 Value of as food 178 an to /""/' s Turpentine, source of ... . Turtle, example ol Reptllia 7. 129 green, use of as 1 1 . 13] skeleton of 190 Turtles, discussed 130 Twining petiole, of clemal (fig.) . . ... Ol nast urt mm (fig.) . Twining plants, direction of curve of Twining stem of dodder (fig.) Twining stems Two-parted flower of mint (fig.) Tympanic cavity Tympanic membrane . . Types, of mosses I fig. I . . of twigs (fig.) Typhoid fever, a bacterial f bacteria on Ureter, of frog 1 17 ol man 2tfi Urethra, of man Urine, defined • 308 Urinary bladder of frog 117 Useful birds. .\. in.. Ml 42 INDEX References are to pages Vaccination, discussed . . . Vacuole, food, of amoeba . . contractile Vacuoles, in nerve cells . . . Valves of arteries and veins . . of stomach Vapor, a form of water . . . Variations in legs of birds . Varied diet of man .... Various forms of cells in human body (fig.) . . . Vascular bundles, formation of tubes by of root of woody stems Vascular system in plants . . Vase-like leaves of pitcher plant Vaseline, use of in transpira- tion experiment Vase-shaped organs (arche- gonia) of moss Vedalia, beneficial beetle . . Vegetable food, highest form of Vegetable forms of protein cheaper than meat . . . Vegetable nitrogen, source of Vegetables, new varieties pro- duced by cross-pollination . food of man Veins, compared with fibro- vascular bundles .... diagram of (fig.) of leaf 268, of man of the leaf of pteris (fig.) . . of wing of insect Velamens Ventilation room at night, direct heating (fig.) indirect heating (fig.) . . . room in daytime, direct heat- ing (fig.) indirect heating (fig.) • . • Ventral blood vessel of earth- worm 250 48 49 225 202 168 9 136 170 189 268 268 287 278 389 275 365 27 311 317 400 306 2 268 201 272 197 371 29 399 195 197 196 197 196 82 Ventral nerve chain of cray- fish 90 Ventral surface of earthworm 80 Ventricle (fourth) of brain . . 119 Ventricles of heart . . . . 201 Venus mercenaria, edible mol- lusk 100 Venus's flytrap (fig.) .... 391 rapid movement of .... 392 use of leaves in 294 Vermiform appendix . . . 168 Vertebrates, a group of ani- mals 6 discussed 103 Vesper sparrow, at hemp and millet station 148 Vetch, member of pulse family 329 Villi, described .173 Villus, diagram of (fig.) . . . 174 Vines, comparison with tree trunks .... ... 286 Violet, capsule of (fig.) . 308, 310 cleistogamous flower of . . . 302 example of irregular flower . 302 fruit of (fig.) ....... 308 long-spurred (fig.) ..... 397 plant (fig.) 301 Virginia deer (fig.) .... 156 fawns of (fig.) 156 Virgin forest (fig.) 379 Virus in inoculation .... 252 Viscera of clam 98 Visceral ganglion of clam . 98 Vitreous humor 216 Vocal cords, location of . . . 194 Voice box (fig.) .... 193, 194 Voluntary muscle cells (fig.) 188 Voluntary muscles .... 188 Volvox 55 colonial protozoa, example of . 55 described (fig.) 56 Vomiting 168 Vorticella (fig.) 52 Vultures, beneficial birds . . 147 example of Raptores .... 141 toe of 140 W Walking sticks 20 Walnut, family discussed , . 327 I \ hi \ i.; Walnut, continut d plant protein in English • . . IT" tree (fig.) twig (fig.) Warbler, yellow, nest <»f (fig.). 142 Warm-blooded animals . . IfiO Warm milk, moltiplicatioo <»f bacteria in 360 Warmth. ;i condition of the growth of bacteria 34 1 Washing away of soil by floods 386 Wasp fly, beneficial insert . . n Wasps, members of Bymenop- tera 20 Waste land, after a fire I figs. I . 381 Waste materials of photosyn- thesis; 276 Waste products of IkmIv . . 206 removed by excretion . . . 2\ i S. . . bread, \ aloe of ai foiMi . . . ] 7 ^ breakfasl food, value 0 i 178 cereal (fig.) flour, value of as fo< ■•! ... Indehiscenl fruit map «>f production >>t < I member of grass family . one of first cultivated plant s • dlings 1 iiu ) Whip grafting- Mi _- 1 . . White blood corpu.-rles White-breasted nuth. u hole -rain stat iou , White-crowned sparrow bemp ami millet stat ion Whiteflsh, example of a bony fish White grubs eaten by birds White of the eye White pine, value of ... . White-throated sparrow hemp and millet station . . n> Whole grain station, bir.ls frequent ing 149 Whooping cough, a bacterial rtifleanfi e\posUle t0 Wigglers. larva- of mosquito*-* 19 Wild plants, Improvement of by man Willow, flow . -"l Wind-distributed frn." Window-growing plant sponse to light in ... Windpipe .... Wind-pollinated I rfl of grass Family . . characterist ica of id pollination Wine, use of yeast in making Wing-Wee air sues of pine pollen Wing of pine seed Wings, ol birds .... Is ^'' 44 INDEX References are to pages Winter visitants, examples of 141 Wistaria, member of the pulse family 329 Witch-hazel, explosive fruit of 312 Wood, example of organic mat- ter 10 formation of 290 of spruce (fig.) 290 sections of (fig.) 290 Woodchucks, young (fig) • • 157 Wooded area, under govern- ment control 387 Woodpeckers, at suet station 148 (downy) permanent residents . 141 food of 27, 31 holes made by (fig.) .... 27 Wood-pulp, source of ... . 384 Woody stem, sections of (fig.) 289 structure of 287 use of elements in 290 Woody twig, buds of ... . 287 Wool, source of 155 indirect product of plants . . 401 Woolly aphis, member of He- miptera (fig.) 24, 25 Work, of the yeast plant . . . 354 of bean leaf 275 Workers (bees) 35 Worm, in the apple (fig.) ... 18 planarian (fig.) 77 Worm-like animals, classified 6 Worm group, discussed ... 76 summary of 84 Worms, classified 6 Wort, formation of 355 Wren, a useful bird 145 food of 31 X-ray photograph, of appen- dix and part of large intes- tine (fig.) . 169 of Easter lily (fig.) .... 327 of elbow (fig.) 185 of hand of adult (fig.) .... 186 of child (fig.) 186 of human stomach (fig.) . . . 168 Xylem, conductor of water . . 290 in fibrovascular bundle of corn 280 position in vascular bundle . . 269 relation to cambium .... 287 Xerophytes 396 Year's growth of twig, how told 289 Yeast, in bread making . . ' . 179 plant, described (fig.) . . . 354, 355 enzyme of 354 use of 355 reproduction of 3 Yellow fever, carried by mos- quito 42, 239 caused by protozoa . . .47, 234 Yellow pine, value of ... . 385 Yellow swallowtail (fig.) . . 33 Yellow warbler, nest of (fig.) . 142 Yolk, of fish eggs 109 sac on young fish (fig.) • • . HI Youth, a period of life .... 163 Zeppelins, use of hydrogen gas for 8 Zygospore, advantages of . . 341 Zygote of spirogyra .... 341 Zymase, work of 179 IMPORT U8HARY % C State CWIejfe