446 



INDEX 



Radiolarian, 198. 



Ray flower, 44. 



Reflex action, nervous, 403. 



Regeneration, defined, 215. 



Relation, of alcohol to disease, 412 ; 



of bacteria to fermentation, 177 ; 



of birds and reptiles, 310 ; 



of bodily heat to work, 392 ; 



of breathing to exercise, 388 ; 



of environment to diet, 336; 



of flies to disease, 260, 261 ; 



of Protozoa to disease, 196 ; 



of spawning to economic value, 

 281; 



of work to diet, 336. 

 Rennin, 358. 

 Reptiles, study of, 293. 

 Reptilia, characteristics of, 296 ; 



classification of, 297. 

 Reproduction, in simple plants, 199 ; 



in simple animals, 199 ; 

 Respiration, artificial, 389 ; 



effect of alcohol on, 395 ; 



effect of tobacco on, 396 ; 



excretion, 382 ; 



in a cell, 389, 390 ; 



in birds, 301 ; 



in crayfish, 224 ; 



in fishes, 277 ; 



in frog, 286 ; 



in insects, 235 ; 



necessity for, 382 ; 



nervous control of, 384 ; 



organs of, in man, 382. 

 Rest, necessity of, 405, 427. 

 Rhizoids, 149, 153, 155. 

 Ribs, attachment of, 327 ; 



in respiration, 384. 

 Rock fern, 154. 

 Rodents, 313. 

 Root, absorption in, 89 ; 



effect of moisture on, 85, 86 ; 



food storage in, 95 ; 



influence of gravity upon, 84 ; 



passage of soil water in, 90 ; 



tip of, 87. 



Root form, relation of, to plant, 95. 

 Root hair, 88, 89. 

 Root pressure, 107. 

 Root system, 84. 



Roots, adventitious, 96 ; 



air, 97 ; 



and their work, 84 ; 



different from stems, 115; 



parasitic, 97 ; 



prop, of corn, 96 ; 



water, 96. 

 Roundworms, 217. 



Salamander, spotted, 291. 



Saliva, function of, 356. 



Salmon leaping a fall, 281. 



Sand shark, 284. 



Sandworm, 216. 



Saprophytes, 149, 151. 



Sea anemone, 208. 



Sea lion, 313. 



Seasonal variation of plumage, 309. 



Seaweeds, 144, 145. 



Seed dispersal, 52, 53, 80. 



Seedling, defined, 79. 



Seeds, and seedlings, 65 ; 



formation of, 52 ; 



uses of, 80 ; 



winged, 55, 56. 

 Selective absorption, 194. 

 Selective breeding, 316. 

 Selective planting, 81, 82. 

 Self-control vs. appetite, 416. 

 Self-pollination, 38. 

 Sense organs, 206, 286, 236. 

 Senses, in birds, 302 ; 



in fishes, 276 ; 



in man, 406. 

 Serum of blood, 367. 

 Sexual development of simple ani- 

 mal, 200. 



Sexual reproduction, in animals, 

 192, 194, 203, 208, 209, 215, 280, 

 288; 



in plants, 148, 150, 153, 154, 156. 

 Shelf fungus, a saprophyte, 173. 

 Shipworm, damage by, 271. 

 Shrimps, 227, 228. 

 Skeleton, and muscles, 324 ; 



appendicular, 326, 327 ; 



axial, 326 ; 



of birds, 300 ; 



of dog, 325 ; 



of fishes, 279; 



