INDEX 39 
References are to pages 
Vascular system in plants 268 
Vase-like leaves of pitcher plant 366 
Vaseline, use of, in transpira¬ 
tion experiment .... 284 
Vase-shaped organs (arche- 
gonia) of moss .... 329 
Vedalia, beneficial beetle . . 34 
Vegetable nitrogen, source of . 257 
Vegetable oyster, biennial root 252 
food of man.245 
Veins, compared with fibro- 
vascular bundles .... 267 
of leaf.276 
of man .453 
Velamens. 253, 373 
Venation.276 
Veneer.352 
Ventilation.447 
Ventral blood vessel of earth¬ 
worm ..182 
Ventral nerve chaiA of crayfish . 64 
Ventral surface of earthworm 179 
Ventricle (fourth) of brain . 89 
Ventricles of heart. 452 
Venus mercenaria, edible mol- 
lusk.192 
Venus’s flytrap.289 
rapid movement of ... 367 
use of leaves in. 367 
Vermiform appendix .... 408 
Vermin. 514 
Vertebrates, a group of animals . 9 
discussed. 68 
Vetch, member of pulse family 299 
Viability. .223 
Villi, described.414 
Violet, capsule of.238 
cleistogamous flower of . . 204 
example of irregular flower . 204 
Virgin forest in United States . 348 
Virus in inoculation . . . 511 
Viscera, defined.188 
Visceral ganglion of clam 188 
Vitamines. 245, 415 
Vitreous humor . 473 
Vocal cords, location of . . . 445 
Voice box, the . 445 
Voluntary muscle cells 437 
Voluntary muscles . . . 436-437 
Volvox, described.153 
Vomiting . 408 
Vultures, beneficial birds . . 116 
example of Raptores . . . Ill 
W 
Walking sticks.29 
Walnut, family discussed . . 297 
plant protein in. 222 
tree.351 
Walrus. 134 
War gardens.424 
Warm-blooded animals . . . 451 
Warm milk, multiplication of 
bacteria in.316 
Warmth, a condition of the 
growth of bacteria . . . 311 
Washing away of soil by floods 351 
Wasp fly, beneficial insect . . 54 
Wasps, members of Hymenop- 
tera. 45 
Waste materials of photosyn¬ 
thesis (by-products) . . . 279 
Waste products of body . . . 457 
removed by excretion . . . 457 
Water, a necessary condition for 
growth of, bacteria . . . 311 
basis of classifying plants in 
societies.369 
contains bacteria . . . . 310 
composition of. 12 
sanitary measures for protect¬ 
ing .498 
supply, student report on . 499 
Water beetles, destroyers of 
mosquitoes.55 
Waterlilies, air supply of . 370 
structure of stem of ... 370 
Water roots.251 
Water snail, host of liver fluke . 176 
Water supply.462 
Wax, in ear.476 
produced in U. S., value of . 49 
Weasels, destroyed by hawks . 115 
harmful animals.137 
Webbed toes, of swimming 
birds . .. 108 
Wedding flight of bee ... 48 
Weeds, common, list of . . . 301 
definition of.302 
in plant succession .... 375 
reasons for success of . 302 
seeds destroyed by birds . . 117 
