Vaccination, reasons for, 325-326 



Vaccination, smallpox, 325 (see Inoculation, Im- 

 munity) 



Vaccine, 325-326, 327, 339; influenza, 340; prepara- 

 tion of, 326, 327; smallpox, 325; yellow fever, 340 



Vacuoles, 106, 111; cell, 107 \ root hair, 150 



Vacuum, 229 



Vagina, def., 433 



Valves, heart, 213, 220, 220; lymphatic, 221; vein, 

 217-218, 217 



Van Helmont, Jan, plant experimenter, 137 



Variation, in bean length, 487; caused by environ- 

 ment, 485: environmental, 485-492; in evening 

 primrose, 486; and evolution, 557-558; liereditary, 

 479-485; in man, 573-577; measurement of, 485- 

 487; partly explained, 473-474; in pig, 486; in 

 soldiers, 487 



Varieties, def., 495; in classification, 101 



Vascular bundles, in corn, 1S7 



Vascular cylinder, 153; root, 152, 1S2; stem, 154 



Vegetables, seedless, 450 



Vegetative propagation (see Vegetative reproduc- 

 tion) 



Vegetative reproduction, 447-449; in African vio- 

 lets, 449; in bryophyllum, 448; and plant breed- 

 ing, 502; in potato, 448; in strawberry, 448; in 

 sweet potato, 449; in tulip, 448; in white potato, 

 449 



Veins, 206, 207, 207, 213, 214, 215, 216, 217-218, 

 218, 219, 219, 220, 221; leaf, 137, 138, 138, 154; 

 of leaves, 138, 138, 139, 154, 157, 158; structure 

 of, 215; valves, 217 



Vena cava, inferior, 219; superior, 213, 219 



Venereal disease, 332-333 



Ventilation, 242 



Ventral, def., 202 



Ventricles, 213, 213, 214, 215, 218, 218, 219, 219, 

 220, 220 



Venus's flytrap, 304-305, 306 



Vertebrae, 15, 271 



Vertebral column, 271 



Vertebrates, def., 15; brain, 273, 273-274; classes, 

 16; kinds, 15-39; number, 39; structural resem- 

 blances, 547; table of classification, 65 



Vestigial structures, 550-551; in porpoise, 551 



Vestigial wing, in fruit fly, 472; and temperature, 

 490 



Villus, 198, 198, 206, 221 



Virulence, of germs, 338 



Virus, 339-342; common virus diseases, 340; in- 

 fluenza, 339; measles, 327; and rabies, 324; small- 

 pox, 340; tobacco mosaic, 340 



Vision, 280-281; and cerebrum, 272 



Visual purple, and vitamin A, 179 



Vitamins, 176-183; A, 177-179, 181-183; and cook- 

 ing, 182; B, 177; Bi, 179, 183; B2, 183; experiment, 

 179; B complex, 179-180; C, 178, 180-183; ex- 

 periments, 176; D, 181-183; experiments, 180, 

 181; E, 182, 183; G, 183; in common foods, 173; 

 K, 183, 211; pills, 182-183; review table, 183 



Volcanic eruption, 524 



Voluntary muscle, 131-132, 132 (see Muscle) 



Von Behring, Emil, 328-329 



Von Mohl, Hugo, 126 



Vorticelia, 62, 269 



Vultures, 21 



Walking stick, and protective adaptation, 461 

 Wallace, Alfred Russell, and evolution, 556 



Warm-blooded, def., 16 



Wasp, nest, 263 



Wassermann test, for syphilis, 333 



Wastes, def., 199, 206, 208, 237; diagram, 237; dif- 

 fusion, 206-207; and kidney, 238; removal, 237- 

 240; and sweat glands, 239 



Water, in the diet, 175-176; in diffusion, 121-124; 

 distilled, 123; excretion, 230, 238, 241; movement 

 in plants, 151, 157-160; in photosynthesis, 140- 

 142, 145; in protoplasm, 108, 109; in soil, 150- 

 151; test for, 116; as waste, 237, 237 



Water, birds, 21-22, 23; fleas, 373; moccasin, 27-28; 

 ocean life, 74 



Water-living animals, 18, 19, 30-34, 53-56, 58-64. 

 74; plants, 73-75, 74, 76 



Watershed, after fire, 401; def., 345 



Water supply, and public health, 344-345; and ty- 

 phoid deaths, 345 



Weathering, def., 522, 522 



Web of life, 381 



Web, spinning of, 263-264 



Wedgwood-Darwin, pedigree, 512 



Weeds, 385, 385 



Weight, and calories, 170-174; reducing, 171; rela- 

 tion to diet, 174-175 



Weismann, August, and acquired characters, 488- 

 489; experiment with mice, 489 



Whale, 18; flipper bones, 547 



Wheat, 84-85, 141, 149; Kanred, 502 



White ant (termites) 49 



White corpuscles, blood cells, 208, 209, 210, 210; 

 of lymph nodes, 222 



White matter, of brain, 272; of spinal cord, 272 



"White plague," tuberculosis, 321-322 



Whooping cough, immunity, 316 



Wildlife, conservation of, 405-406 



Willow, 86 



Wilting, of plants, 160 



Windpipe, of man, 189, 227, 228 (see Trachea) 



Wisdom teeth, 203 



Wood, heart, 156, 157; pulp, 383; root fibers of, 152; 

 sap, 156 



Worker, ants, 47, 47; bees, 48-49, 48 



World War II, and malaria, 349 



Worms, 57-58; sperm, 423 



Wounds, puncture, 331; and sulfa drugs, 333-334; 

 and tetanus, 331 



Wriggler, of mosquito, 352 



Wyoming, fossils, 530 



X-rays, and cancer, 361; and fruit flies, 481; of lily, 



439; and tuberculosis, 322, 323 

 Xylem, 152, 153, 156, 157; of root, 152; of stem, 



154, 154 



Yale University, study of behavior. 296 



Yeast, 77; reproduction, 413-414; 413 



Yellow fever, 340, 351-354 



"Yellow Jack" (see Yellow fever), 351 



Yolk, 422, 425-426, 430, 431, 432, 461 



Yolk sac, of fish, 425-426 



^ ouiig (see Offspring) 



Zebra, 14 



Zoologist, 3 



Zygospore, of bread mold, 417; del"., 416; of spiro- 



gyra, 416 

 Zygote, def., 418; 425, 428; of flowering plant, 443. 



443 



616 



