430 



INDEX 



Relation, of environment to diet, 

 280; 



of green plants and animals, 15, 

 161, 162; 



of sex to diet, 280 ; 



of work to diet, 277 ; 



of yeasts to man, 135. 

 Rennin, 303. 

 Reproduction, 103, 181 ; 



importance of, 52 ; 



in seed plants, 173, 174 ; 



of cells, 50 ; 



of Paramoecium, 169. 

 Reptiles, 186. 

 Reptilia, 188. 

 Reserve air, 334. 

 Residual air, 334. 

 Respiration, 66, 181 ; 



and alcohol, 346 ; 



and nervous control, 334 ; 



and tobacco, 346 ; 



mechanics of, 332, 333; 



necessity for, 329 ; 



organs of, 330 ; 



of cells, 332 ; 



of leaves, 96. 

 Retina, 360. 

 Rhizoids, 133. 

 Rhizopoda, 182. 

 Rice field, 123. 

 Ringworm, 134. 

 Roaches, 216. 

 Rock fern, 175. 

 Rockweed, 176. 

 Roots as food, 119; 



as food storage, 83 ; 



downward growth of, 72 ; 



fine structure, 73 ; 



give out acid, 79, 80 ; 



hairs, 74, 75 ; 



influence of gravity, 72 ; 



influence of moisture, 73 ; 



passage of soil water, 76 ; 



pressure, 101 ; 



system, primary, secondary, ter 

 tiary roots, 72 ; 



uses of, 71. 

 Rotation of crops, 81. 

 Roundworms, 183, 228. 



Rules of habit formation, 356. 

 Russian thistle, 129. 



Saliva, 69, 299. 

 Salivary glands, 299 ; 



glands of frog, 243. 

 Salmon, 201, 241. 

 Sand shark, 186. 

 Sandworm, 184. 



Sanitarium for tuberculosis, 394. 

 Sanitation, 27. 

 Saprophytes, 131. 

 Scavangers, 150. 

 Schleiden and Schwann, 398. 

 Schultz, Max, 398. 

 Sclerotic coat, 360. 

 Sea anemones, 183. 

 Secretion, 299, 308. 

 Secretions, internal, 317. 

 Section, of ear, 359 ; 



of timber, 111. 

 Sedgwick, William T., 312. 

 Seed, 54 ; 



how scattered, 56 ; 



plants, reproduction, 174 ; 



why it grows, 58. 

 Seedlings of bean, 63. 

 Segmented worms, 183. 

 Selection, artificial, 253 ; 



natural, 253. 

 Selective planting, 254. 

 Semicircular canal, 359. 

 Sensations, 350. 

 Sense organs, 181 ; 



of fish, 233 ; 



of frog, 242. 

 Senses, 357. 

 Sensory nerves, 351. 

 Sepals, 35. 

 Series, animal, 182. 

 Serum, 314. 

 Sewage disposal, 386. 

 Sex, relation to diet, 280. 

 Shelf fungi, 132. 

 Sieve tubes, 97. ' 

 Simple animal, development, 177. 

 Simplest plants, 166. 

 Skeleton, of dog, 185 ; 



of fish, 237 ; 



