720 - Index 



Sexual reproduction, 57-60, 203; egg cells and 

 sperm cells, 59-60; isogamy, heterogamy vs., 

 57-59; life cycles, 60-62 



Shaffer, B„ 532 



Shaw. T. J., 123 



Shipworms, 651 



Shock, 407, 409; hypoglycemic, 341 



Sickle cell anemia,' 86, 505, 507 



Sieve tubes, 241. 243, 244, 245, 246, 247 



Sigmoid flexure, 315 



Silurian period, 563, 565, 566 



Sinus gland, 417 



Sinuses, 284, 368 



Skeletal muscles, 17, 286, 287, 431-39, 460; con- 

 tractile mechanism, fine structure of, 437-39; 

 contractile process, chemical aspects of, 435-36; 

 contraction: the single twitch, 433-31; contrac- 

 tion: the tetanus, 434-35; craniospinal nerves 

 and, 460; gradation of contractions, 435; heat 

 production, 436-37 



Skeleton, origin of. 283; segmented axial, 666 



Sleep movements, 261, 262 



Slime molds, 17, 36, 37, 602-04 



Slugs, G49, 653 



Small intestine, 296, 297, 310-11, 339; movements 

 of, 314 



Smell, receptors of, 420-21 



Smith, H. W.. 375 



Smuts, 173, 606. 607, 610 



Snails, 649, 650, 651, 653 



Snyder. L. H„ 504 



Sociology, 14 



"Sodium jump," 123 



Solar energy, perpetuation of life and. 185-86 



Solation, 94-95 



Solids. 67 



Solutions. 92: acid, 73-74; basic, 73-74; hypo- 

 tonic, 118-21; isotonic, 118; neutral, 73-74; 

 true, 71 



Solvents, 71, 92, 117 



Somatotropin, 410-11 



Sorus, 203, 204 



Spallanzani, L., 186. 305 



Species, adaptation, 543-44, 575; extinction of, 

 545-48; interdependence of, 573-74; multipli- 

 cation of organisms. 538-41; natural selection 

 and. 541-43; origin of (.we Origin of species); 

 stability of, 544—45; taxonomic category. 593 



Spectrometer. 142 



Spectroscope, 105, 149 



Sperm, 51, 52-54, 381, 385; egg cell and, 59-60; 

 male gamete, 57 



Sperm cell, 273-74 



Sperm ducts, 381 



Spermatids, 54, 477, 478 



Spermatocytes, 52-54; primary, 177; secondary, 

 477 



Spermatogonia, 52, 53, 385, 476 



Sphenopsida, 614—15 



Sphincters, anal, 315; ileocaecal, 315 



Spices, plant products, 257 



Spiders, 655 



Spinal cord, 281, 282, 458, 664; conduction path, 



463; structure of, 458-60 

 Spinal nerves, 460-61 

 Spindle fibers, 41 

 Spindles, 28, 42, 43, 44 

 Spireme stage, 41 

 Spirilla, 173, 176, 602 

 Spirogyra, 30, 55, 57, 58, 59, 119. 167, 168, 210; 



life cycle of, 60, 6f 

 Spleen, 335 



Sponges, 629-30; gastric vacuoles of, 291-92 

 Spongin, 629 



Spontaneous generation, 186 

 Sporangia, 204, 205, 211, 212, 213, 214 

 Sporangiophores, 175 

 Spore capsules, 52. 175 

 Spore mother cells, 57 

 Spores, 40, 51, 56-57, 204. 205, 209, 211, 214; 



reproductive, 56; swarm, 57 

 Sporocytes, 204 

 Sporophores, 606 

 Sporophyte, 203-04, 208, 209, 212, 215, 221- 



Sporophyte generation, 61, 216, 242 



Sporozoa, 625. 628 



Sporulation, 56-57 



Sf/mimata, (371 



Squids, 619, 650, 652, 653 



Stability of species, 544—45 



Stanley, W. M., 9 



Staphylococcus, 602 



Starches, 76. 80, 81; digestion of. by saliva, 110 



Starfish. 660, 661, 662, 663 



Starvation, 139, 345 



Statocyst, 424 



Statoliths, 424 



Steapsin, 312 



Stearic acid, 82 



Stems, 237, 241: conduction in, 249; economic 

 importance of. 257: functions ol, 246-49; struc- 

 ture ol, 248-49 



Steiiostomum grande, 395 



Stern, K. C, 105 



Sternal sinus, 319 



Steroids. 82-83 



Stiiliococcus, 589 



Stimulation, stimuli and, 193-200; successful 

 190-93 



Stimuli, classification of. 193-94: stimulation and. 

 193-200 



Slinging ray, 441 



Stolons, 175 



