5 28 



ELEMENTARY BIOLOGY 



Trench fever, 410 



Trimorphic flowers, 305 



Trimorphic insects, 357 



Tropism, 37, 38, 230 ; and reflexes, 



218 ; and senses, 224 ff. 

 Tubercles, bacteria in, 67 ; nitrogen, 62 

 Tuberculosis, 152, 386, 389, 506, 508 

 Turnspit animals, 460 

 Type, mixed, 440 

 Typhoid fever, 391 ; and flies, 399 ; 



and water, 392 



Underfeeding, 288 



Underwing moth, 352 



Unit characters, law of, 448, 449, 451 



Urea, 144, 201, 204 



Urine in diagnosis, 205 



Vaccination, compulsory, 394 ; against 



typhoid fever, 197 ; and vaccines, 



198 



Vaccines, see Vaccination 

 Valves of heart, 186, 190 

 Vanessa butterfly, 287 

 Vanilla, 312 

 Variation, 258, 437, 472 ; causes of, 



438 ; physiological, 438, 439 ; in 



size of similar units, 436 

 Vegetarianism, 105 

 Veins, 185 ; of leaves, 34, 70, 175, 176 

 Ventilation, 154 ff. ; and efficiency of 



work, 185; and moisture, 189; of 



lungs, 148, 152 ; regulation of, 395 ; 



summary on, 173 

 Ventricles, 185, 186, 187 

 Vermiform appendix, 82, 468 

 Vertebrata, 432 

 Vertebrates, 482, 492 ; brains of, 497 ; 



reproduction in, 330 

 Vessels, blood, 185 ; in plants, 44, 



174, 176 



Vestigial structures, 468 

 Vibrations, perception of, 238 

 Villus, 86, 87 

 Vinegar and bacteria, 397 

 Vitamines, 109 

 Voit, Carl, food doctrines of, 90, 93, 



99 

 Volume of cell in relation to growth, 



265 



Voluntary muscles, 219 

 Volvox, 276 



Von Baer's Law of Recapitulation, 278 

 Vries, Hugo de, 440, 442, 461, 462, 



473 



Walking-leaf insect, 354 



Walking-stick insect, 353 



Wallaby and young, 334 



Wallace, Alfred Russel, 472 



War, the Great, 64, 108, 130, 133, 142, 



216, 243, 354, 383,410, 514 

 Warm-blooded animals, 337 

 Wastes of organisms, 201 ff. See also 



Excretion 

 Water, essential to gametes, 328 ; in 



food-making, 53 ff. ; in growth of 



plant, 38; and life, 50, 52, 338; 



with meals, 114, 117; related to 



sprouting, 27 



Water power and forest, 380 

 Water supply, 122, 123, 391; and 



forest, 378 ; and typhoid fever, 



392 



Wax, 413 



Waxwing, cedar, 428 

 Wealth, biology related to, 4. See also 



Economics 



Weapons and tools, 499 

 Weevils, 416; cotton-boll, 418 

 Weismann, August, 459 

 \Vheat, breeding of, 450 ; immunity 



to rust in, 451 ; rust of, 411 

 Wheelworms, 482 



Whiteness of fur related to tem- 

 perature, 353 

 Wood, conservation of, 384 ; in roots, 



43,44; in stems, 174, 175; supply 



of, 382, 383 ; uses of, 377 

 Woodpecker, red-headed, 428 

 Work, alcohol and, 136; hours of, 



213; rate of, 211; relation of, to 



food requirements, 100-101 ; and 



rest, 214 

 Work conditions, regulation of, 394, 



395; standardizing, 216 

 Wounds, treatment of, 191 



Xylem, 176 



Yeast, 23, 133, 291-292 



Yellow fever, 406 ; reduction of, in 



Cuba, 409 



Yellow-bellied sapsucker, 427 

 Young, protection of, 371. See also 



Development and Infancy 

 Youth, 335 



Zygospore, 297 



Zygote, 296, 297, 332, 459 ; origin of, 

 457 



