INDEX 



703 



Reproductive glands, 394 



Reptiles, 256-260 ; characteristics of, 



259 ; classification of, 260 ; relation 



to birds, 266-267 

 Research worker, profession, 653 

 Residents, bird, 551 

 Resources, conservation of natural, 



572-601 

 Respiration, artificial, 408-409 ; cell, 



405 ; comparison of frog with man, 



403; of birds, 263-264; by leaves, 



165; need of, 44; organs of, 403- 



404 

 Responses, adaptive, 426 ; conditioned, 



443 ; of living things, 37 ; of plants 



and animals, 422-426 

 Rickets, deficiency disease, 334-335 

 Rind, of corn stem, 170 

 Ringworm, 199 

 Robin, 552 ; food of, 548-549 

 Rodents, 269 



Root, structure of, 143-144 

 Root cap, 143, 144 

 Root hairs, 22, 135-136; function of, 



145-146; how take in water, 147-150; 



laboratory exercise on, 144 ; structure 



of, 144-145 ; why absorb water, 149 

 Roots, factors influencing growth, 140- 



143 ; influence of gravity, 140—141 ; 



influence of water on, 141, 143; pur- 

 poses of, 150 ; use of, 21, 22-23 ; used 



as food, 521-522 

 Rootlets, 140 

 Root pressure, 149 

 Root systems, 140-141 

 Rose family, 209, 210 

 Ross, Major, investigator of malarial 



fever, 664 

 Rotation, of crops, 188-189 

 Roughage, needed bv bodv, 332 

 Round worms, 228, 493-494; harmful, 



493-496 

 Russian thistle, dispersal of seeds of, 



102, 103 

 Rust, black stem grain, 195-196, 197; 



pine tree blister, 196 



Sac fungi, 196-197 



Salamander, an amphibian, 254-255 



Saliva, function of, 363 



Salivary glands, 363 ; parotid, 363 ; sub- 

 lingual, 363 ; submaxillary, 363 



Salmon, as food, 534-535 ; spawning 

 habits, 588-589 



Salt, as a preservative, 459-460 



Sanitation, definition of, 34 



Saprophytes, 194 



Scallops, mollusk, 240-241 ; used for 

 food, 533 



Scarlet fever, and Dick test, 479 



Schick test, 478-479 



Schleiden, on cells, 657 



School, improvement of conditions, 



501-503 ; lunch and lunch time, 502- 

 503 ; surroundings, 501-502 



School hygiene, 510 



Schwann, on cells, 657 



Scurvy, deficiencv disease, 333-334 



Sebaceous glands, 316, 317 



Secondary roots, 140 



Secretin, 374 



Secretion, of glands, 362 



Seed dispersal, dehiscent fruits, 109- 

 110; indehiscent fruits, 110-111; of 

 flesh v fruits, 108-109 ; of hard seeds, 

 109 ; of weeds, 102-103 



Seed plants, why succeed in life, 100- 

 111 



Seeds, 84 ; dispersal of weed, 102-103 

 factors necessary for germination 

 120-121; germination of, 115-130 

 location of food supply on different 

 125-126 ; of weed, eaten by birds 

 549-550 ; produced by weeds, 102 

 used as food, 522-526 



Seeing, organ of, 440-441 



Segmented worms, 229-231 



Segregation, Mendel's law of, 621-622 



Selective planting, 633-634 



Self-analysis, in selecting a vocation, 

 646-647 



Self-improvement, biology and, 644-654 



Sensation, 43 



Sense organs, 422 ; demonstration to 

 show types of, 427 ; function of, 427- 

 429, 435; health habits of, 448; of 

 birds, 264 ; of man, 430 ; part played 

 in control of body, 435-441 



Sensory neuron, 431 



Sepals, of flowers, 83, 84 



Septic sore throat, 470 



Serum, blood, 388 



Sewage disposal, in community, 505- 

 506 



Sex, relation to diet, 338 



Sexual reproduction, in flowering plants, 

 615-616 ; in Spirogyra, 201-202, 615 



Shellfish, conservation of, 592-593 ; life 

 historv of, 593 



Sieve tubes, 167, 168 



Silkworm moth, fibers made by, 540 ; 

 life history of, 538-539 



Siphonaptera, an order of insects, 238 



Skeleton, human, axial, 319 ; appendicu- 

 lar, 319 ; of crayfish, 233 



Skin, 314; clothing and the, 318; in- 

 fections, 317-318; laboratory study 

 of, 414 ; organ of excretion, 414-415 ; 

 structure of, 316-317 



Sleep, necessity of, 447-448 



Small intestine, absorption from, 378- 

 379 ; digestion in, 374 ; glands in, 

 377 ; movement of, 370 ; structure 

 of, 376, 377 ; villi in, 377-378 



Smallpox, active immunity, 479-480 ; 

 and vaccination, 475-476 



