40 
INDEX 
References are to pages 
Wells, as source of water supply 463 
Wheat, a monocotyledon . . 227 
amount produced by U- S. . 296 
member of grass family . . 295 
one of first cultivated plants . 296 
Where bacteria are found . . 310 
Where foodstuffs are stored in 
seeds.229 
White blood corpuscles . . . 450 
White-breasted nuthatch at 
feeding station . . . . 118 
Whitefish, example of a bony 
fish.71 
White grubs, eaten by birds . 35 
parasite.460 
White oak, uses of.352 
White of the eye.473 
White pine, value of ... . 352 
Whiting, edible fish. 80 
Whooping cough, a bacterial 
disease.489 
Wigglers, larvae of mosquitoes . 28 
Wild plants, improvement of, by 
man. 22 
Wiley, Dr. H. W., quoted . . 506 
Willow tree, source of charcoal . 351 
Wind-breaks.348 
Wind-distributed fruits 241 
Window-growing plants, re¬ 
sponse to light in ... 291 
Windpipe.444 
Wind-pollinated flowers, of 
grass family.295 
characteristics of . . . . 210 
Wind pollination.210 
Winglike air sacs of pine pollen 344 
Wing of pine seed.344 
Wings, of birds.107 
of seeds.241 
Winter visitants, examples of . 112 
Wisteria, member of the pulse 
family.299 
Witch-hazel, explosive fruit of 
238, 241 
Wood alcohol.352 
Wood, example of organic mat¬ 
ter . 10 
formation of ... . 265, 341 
Wood borers.34 
Wooded area, under govern¬ 
ment control.361 
Woodpeckers, at suet station . 118 
(downy) permanent residents 111 
food of.42 
Wood-pulp, source of ... 346 
Woody stem, structure of . . 265 
use of elements in . . . . 267 
Woody twig, buds of ... 264 
Wool, source of.132 
indirect product of plants . 376 
Woolly aphis, member of He- 
miptera.32 
Work of the vascular bundle 268 
Work of the yeast plant . . . 321 
of a leaf.274 
of forest ranger.358 
Workers (bees).46 
Worm, planarian.175 
Worm group, discussed . . . 175 
summary of.184 
Worm-like animals, classified . 9 
Worms, classified. 9 
Wren, a useful bird . . . 115 
food of. 42, 115 
X 
Xerophytes.370 
Xylem, conductor of water . . 269 
in fibro vascular bundle of 
corn.266 
in vascular bundle .... 267 
relation to cambium . . . 267 
Y 
Yarrow, divided leaves of . . 278 
Year’s growth of twig, how told 266 
Yeast, in bread making . . . 321 
plant, described.321 
enzyme of.321 
use of.321 
reproduction of.322 
Yellow fever, carried by mos¬ 
quito .494 
caused by protozoa .... 489 
Yellow pine, value of ... 352 
Yolk, of fish eggs.78 
Youth, a period of life . . . 402 
Z 
Zygospore, advantages of . . 307 
of spirogyra.307 
Zymase, work of.427 
