BIOLOGY AND HUMAN LIFE 



Stomach, 132 f.; glands of, 134 

 Sto'mate, 108, no, 112 

 Stra bis'mus, 238 

 Struggle for existence, 533 ff. 

 Suffocation, 170 ff. 

 Sugar. See Carbohydrates 

 Sumac, economic value of, 441 

 Sun, relation of, to life, 203 f. 

 Sunflower, economic value of, 444 f. 

 Susceptibility, 338. See a/so Immunity 

 Swallowing, 131 f., 219 

 Synapse (si naps'), 220 



Tapeworm, 302, 309, 333 f. 



Tap-roots, 1 1 5 



Taste, in selection of food, 141 ; 

 organs of, 228, 235 



Teeth, 131 ; care of, i56f. 



Temperature, relation of, to sprout- 

 ing, 65 f. ; and breathing, 168; in 

 industrial plants, 380 f. See also 

 Heat 



Tet'aniis, 303, 311, 341 



Texas fever, 524 f. 



Thallophytes (thar6 fits), 77 



Thorax of insect, 15 



Thymus, 177 



Thyroid, 177, 304 



Tick, 335 ; fever caused by, 309 



Tissues, 61, 209, 210; destroyed by 

 parasites, 303 ; and cancer, 482 



Tobacco, injurious to health, 189, 235; 

 and smoking, 422 ff. 



Touch, organs of, 199 



Tourniquet, 188 



Towels, public, 358 



Toxins, 340 



Transformation (metamorphosis), 29 



Transmission of communicable dis- 

 eases, 311 



Transpiration, no, 550 



Transportation within organism, 118 



Trees. See Forest 



Trench fever, 328 



Trichina (trl ki'nd), 309, 334 



Tubercles, bacteria in, 301 



Tuberculosis, 303, 311; susceptibility 

 Jto, 346 ^ 



Tym'p^z niim, of insect, 16; of man, 

 229 



Typhoid fever, 303, 311, 342, 343; 

 and flies, 317, 319; and vaccination, 

 344. 345 ; and water supply, 352 



Unit characters, law of, 513, 514 f., 



524 ff. 

 Urine, 194; in diagnosis, 196 



Vaccination, 343 ; against smallpox, 

 344; against typhoid, 344, 345; 

 against diphtheria, 344 



Valves of heart, 182 



Vanilla, 50, 51, 437 



Variation, 491; causes of, 491 ff.; in 

 size of similar units, 492 ; physio- 

 logical, 494, 495 ; inducing, 504 f. 



Veins, 181, 190; of leaves, 108, no, 

 116, 1 19 



Ventilation, of lungs, 162, 164; hy- 

 giene of, 168; and efficiency of 

 work, 168 f., 174; and moisture, 

 169; regulation of, 170, 380 



Ventricles, 181, 182 



Vertebrae, 280, 281 f. 



Vertebral column, 281 



Vertebrates, 273 f.; brains of, 221; 

 general plan of, 275 ff.; skeleton 

 of, 281 ff.; development in, 285; 

 economic value of, 453 ; reproduc- 

 tion in, 488 



Villus, 135, 136, 154 



Vitamins (vl'td minz), 102 f., 104 f., 

 140, 147, 285, 287, 417 n., 440, 



443 

 Volvox (vol'voks), 210 



Vorticella (vor tl sel'd), 80 



Walnut, economic value of, 437 



Wasp, 85 



Wastes of organisms, 193 ff. See also 

 Excretions 



Water, relation of, to sprouting, 65 f. ; 

 and life, loi, 104 ; in food-making, 

 107; in growth of plant, no, 496; 

 with meals, 154 ; essential to health, 

 195 f., 367; supply of, 352 f.; and 

 the forests, 55of. ; as source of 

 power, 551 f. 



Wealth, biology related to, 100, 

 414 



Weeds, 436, 437, 442, 444 



Weevils, 563 ; cotton-boll, 564 f. 



Wheat, breeding of, 514 f. 



W^heelworms, 82 



Widal test for typhoid, 342 



Willow, economic value of, 437 



Wings, 15 



