Ritchie. Waller S., 109 



Robin, 16 



Rockefeller Institute for Medical Research, and 



pneumonia vaccine, 339 

 Rocks, 521-525; age of, 525; and earth liistory, 525- 



544; formation of, 521; formation of sedimentary, 



523; how exposed, 529; kinds of, 521, 523, 524; 



strata of, 523; tilted strata of, 524 

 Rockweed, 74, 75 

 Rodents, 18 

 Rooster, 254 

 Roots, 148-153, 152, 157; cap, 152; as food, 148; 



growing point, 152, 152; hairs, 150, 150-151; 



ivy, 148; length in rye, 148; orchids, 148; and 



plant responses, 303-304; structure of, 151-153; 



sugar beet, 149; tap, 149; use to plant, 148; 



wheat, 149 

 Rose, 86; wild, 86 



Ross, Ronald, and malaria, 349-350 

 Roughage, 176, 198 

 Roundworms, 40, 57, 66 

 Rubber, 88, 383 



Runner, of strawberry, 448, 449 

 Rusts, 118, 386 

 Rye. 141 



Saber-toothed tiger, 528 



Safety, home check list for. 363 



St. Martin, Alexis, and gastric digestion, 194 



Salamanders, 31 



Saliva, 190, 192, 194, 196 



Salivary glands, of mosquito, 44; of man, 189, 192, 



199 

 Salivary juice, 194 

 Salmon, life cycle, 34 

 Salt, 109, 111 

 Sanctuaries, def., 406 

 Sand dollar, 56 

 Sandstone, 523, 529 

 Sanitation, def., 343-344 

 Saprophyte, def., 374; 374 

 Sapwood, 156 



Scale insects, 46; control of, 394 

 Scales, bird, 20, 21; fish, 32, 32; of insect wings, 43; 



reptile, 26 

 Scallop, 55 



Scarlet fever, and carriers, 347; immunity, 316 

 Scavengers, def., 21; 210 

 Schaefer respiration method, 232, 233 

 Schick, Rela, and diphtheria, 329; test, 330 

 Schleiden, Matthias, 125 

 Schwann, Theodor, 125 

 Science, and improvement of man, 516 

 Scion, def., 502; 503 

 Sclerotic coat, of eye, 280, 280 

 Scorpion, 51, 53 

 Scouring rush, 79 



Scurvy, 176, 176, 178, 180-181, 183, 311 

 Sea, anemones, 58-59, 59; lettuce, 75; lily, 56; lion, 



18, 19; urchin, 46 

 Sea urchin, 46; and parthenogenesis, 424 

 Seal, 18; appendage, 549 

 Seaweeds, 74-75 

 Secondary growth, of stems, 157 

 Secondary sexual characteristics, 421-422; in birds, 



421; in deer, 421; in frog, 435; and hormones, 422; 



in mammals, 421-422; in man, 422; in spiders, 



422 

 Secretin, 200, 246 

 Secretion, def., 125; as conditioned response, 288; 



as reflex, 262 



Secretions, 9-10; digestive, 190-197; internal, 246- 



258 

 Sediment, 523; and fossil formation, 526, 527 

 Sedimentary rock, formation of, 523; strata of, 523- 



523, 524, 528, 529; tilted, 524 

 Seedless, fruits, 449-450; vegetables, 450 

 Seeds, def., 438, 444; agents of dispersal, 445; bean, 



438; coals, 438; corn, 438; development of pea, 



444; dispersal, 445, 445; formation, 438-439, 442- 



443; in plant life cycle, 445; sprouting, ISO, 438 

 Segments, abdominal, 41; worm, 57 

 Segregation, in four o'clock, 464-467, 466, 467; in 



fruit fly, 470, 471; in garden pea, 468-469, 469; 



in guinea pigs, 470; in squash, 469; in rats, 469; 



law of, 468-470 

 Selection, animals, 496; in breeding, 493-496; in 



corn, 495; def., 494; eS"ects explained, 495; nat- 

 ural, 556-559, 561; in plants, 493-494; procedure, 



494-495; of strawberry, 494 

 Self-pollination, def., 441-442 

 Semicircular canals, 281, 282 

 Semmelweis, and blood poisoning, 331, 332 

 Sensation, and brain, 272; and receptors, 279-282; 



and reflex arc, 278-279; and skin, 242 

 Sense organs, 261 

 Sensitive plant, 304, 305 

 Sensory neuron, 278, 278 

 Sensory region, of brain, 272 

 Sepals, 439, 439 



Serous membrane, of artery, 216; def., 131; 194 

 Serum, blood, 211 ; experiment in resemblances, 550; 



immune, 331 

 Seventeen-year locust, 49 

 Sewage, and bacteriophage, 340; disposal, 344; and 



water supply, 344-345 

 Sex, chromosomes, 472-473; heredity of, 472-473; 



organs, 255, 422; effect of removal of, 254 

 Sex-linked heredity, 473, 473 

 Sexual reproduction, animal, 421-437; def., 417- 



418; plant, 438-453; simplest, 351, 351, 415-418, 



416, 417 

 Shale, 523, 524, 529 

 Shapiro, H. L., and races of man, 575 

 Sheath, of neuron, 274 

 Sheep, 16, 99, 104, 382; Ancon mutation, 498; and 



anthrax, 324; bighorn mountain, 99; brain, 271; 



merino, 493, 494; and overgrazing, 403 

 Sheeting, def., 405; and soil erosion, 405 

 Shellfish, and typhoid, 348 

 Shells, 30, 30, 53, 54, 54, 56, 56, 59, 60, 60, 64:, 64, 



526, 543 

 "Shipworm," 55 

 Shortfingeredness, 509 

 Shrubs, def., 80 

 Siamese cat, heredity, 465 

 Siberia, fossils in, 528 

 Sieve plate, 153 



Sieve tubes, 156, 157; of roots, 153 

 Silkworms, and disease, 321; life cycle, 43 

 Silt, def., 523 



Sinanthropus pekinensis, 566 



Sinuses, 226, 364 ^ 



Sinusitis, def., 364 i' 



Sire, def., 497 

 606, a drug, 332 

 Sixfingeredness, 509 

 Skeleton, cat, 548; eohippus, 541; fossil fish, 525; 



frog, 548; horse, 541; porpoise, 551; snake, 28; 



turtle, 548 

 "Skeleton," arthropod, 41; invertebrate, 39 

 Skin, 129, 238, 239-243, 240, 256; and body tem- 



613 



