Distemper, 316 



Distribution, of organisms, 551-552; of races, 575 



Divers, and "bends," 233 



Division, ameba, 412-413, 413; animal nucleus, 458; 

 cell, 456-459, 457, 458; embryo sac, 441, 441; 

 Paramecium, 412; of plant nucleus, 457; pollen 

 grain, 442, 442; i)rimary sex cells, 460-461, 461; 

 yeast, 413-414, 413; zygospore, 416; zygote, 424- 

 426, 425, 443 (see Reproduction) 



Dodder, 374 



Dog, brain, 273; conditioned response, 289; dis- 

 temper, 316; rabies, 324-325; skull, 193 



Dominance, in fruit fly, 470; law of, 468 



Dominant, def., 467-468 



Donor, of blood, 211 



Double nucleus, def., 441; of ovule, 441 



Draftees, causes of rejection, 364; rejection of, 362 



Drawing, prehistoric, 571 



Drinking fountains, 348 



Drosophila melanogaster (see Fruit Fly) 



Drugs, and disease, 332; sulfa, 333-334 



Duckbill, 20 



Duct, of gland, 192 



Ductless glands, 246-258; and dog breeds, 255 



Dust storm, 404 



Dutch elm disease, 386-387 



Dutrochet, Henri Joachim, 125 



Dwarfism, 253 



Dyeing, bacteria, 314 



Dyes, 108 



Eagle, American, 22 



Ear, 281-282, 281; and balance, 282; of corn, 440, 



490 

 Eardrum, 281, 282 

 Earth, changes in, 524-525; changes in surface of, 



521-523; estimating age of, 525; formation of, 521; 



history of, 533-546; studying history of, 525; 



summary of history of, 540-542 ; table of eras of, 



533 

 Earthworm, 40, 57, 58; and learning, 294; sex organs 



of, 421; structure of, 57 

 Echinoderms, 55-56, 56 

 Ecology, def., 381; 381-388 

 Ectoderm, 426 

 Edwards family, 512 

 Eels, life cycle of, 33-34 

 Effectors, 261, 278; in reflex arc, 277-278 

 Efferent neuron, 278 

 Egg cell, 422; hen, 422; mammal, 422 

 Egg nucleus, of flower, 441 



Eggs, ant, 47; development of hen's, 430; develop- 

 ment of i)lant, 440-441; flowering plant, 441; 



formation of, 460-461 ; frog, 423, 428 ; human, 423; 



hydra, 423; insect, 41, 42; mostjuito, 352; used 



for measles vaccine, 327; for typiuis vaccine, 328 

 Ehrlich, Paul, and syphilis, 332-333 

 Eijkman, Christiaan, and beriberi, 177 

 Elastic tissue, of lungs, 228 

 Electrical charge, in diffusion, 151 

 Electricity, form of energy, 120 

 Electron microscope, //, 12; and viruses, 339 

 Elements, def., 108; in protoplasm, 108, 111 

 Elephant, cells, 129; fossil history, 543, 543 

 Elodea, 127, 139 

 Embryo, chick, 549; def., 425; development of bird, 



430-431; of fisli, 424-426; of flowering plant, 443; 



of frog, 428, 549; of human, 432; of pig, 549; of 



plant, 438, 443; of rabbit, 432-433; of turtle, 549 

 Embryo sac, of plant, 441, 441 

 Embryos, resemblances among vertebrate, 549 



Emerson, R. A., and heredity, 490 



Emotions, and behavior, 296-298; in child, 297; and 

 growing up, 297-298; and habits, 294; in lower 

 animals, 297 



Emulsion, 197 



End-brush, 274, 275; and nerve impulse, 276-277; 

 in reflex arc, 277-279 



End products, of digestion, 190 



Endocrine glands, 246-258 



Endoderm, 426 



Endosperm, def., 438, 443, 438, 444 



Enemies, insects, 389-398; microorganism, 311-371 



Energy, in breaking log jam, 120; in conmion foods, 

 169-170, 172; def., 119-120: in hurdling, 119; 

 measurement of heat, 168-169; measuring in food, 

 169-170; measuring in man, 170, 171; in nerve 

 impulses, 376; in photosynthesis, 142, 145; radi- 

 ant, 142; release of. 143; in respiration, 145; in 

 resting cow, 121; from sun, 142; transformation 

 of, 120 



England, tuberculosis in, 321-322 



English sparrow, 22 



Enriched food, 180 



Entomologist, def., 50 



Entomology, def., 391; U.S. Bureau of, 395 



Environment, 261; adaptations to, 560-561, 560, 

 561; and breeding, 504, 504; and chromosomes, 

 481, 482; effect on gene, 490-491; effect on organ- 

 isms, 485-487, 486, 488; and human improvement, 

 513-516 



Enzymes, def., 190-191; 194, 196; diagram of action, 

 197; where made, 191 



Eoanthropus Dawsoni, 566-567, 567 



Eohippus, 542-543; leg bones, 542; skeleton, 541 



Epidemics, 343; of smallpox, 325—326; study of, 355 



Epidemiology, def., 355 



Epidermal cell, 138-139, 139, 152 



Epidermis, of leaf, 138-139, 139; of root, 151, 152; 

 of skin, 240, 241; of stem, 153 



Epiglottis, of man, 226 



EpitheUal, 129; cells, 132, 227; tissue, 131 



Epithelium, 194, 195; of lungs, 228; of skin, 241- 

 242; of windpipe, 227 



Eras, def., 525; described, 533-542; organisms in, 

 541; pictured, 534, 535, 536, 537, 539 



Erepsin, 196 



Ergosterol, 183; and vitamin D, 181 



Erosion, def., 522; and earth's surface, 521-522; on 

 hillside, 403 



Esophagus (see Oesophagus) 



Essential organs (flower), def., 440; 439 



Eugenics, def., 509; 512-513 



Euglena, 64 



European corn borer (see Corn borer) 



Eustachian tube, 281 



Euthenics, def., 516; 515-516 



Evaporation, from leaf, 159-160; of sweat, 240-241 



Evening primrose, 482, 482-483; chromosome num- 

 ber, 459; effect of environment, 486; nuilant, 482 



Evergreens, 81-82, 82, 91 



Evolution, and adaptations, 560-561; def., 553; evi- 

 den(;es for, 540-544, 547-554, 525, 526, 527, 530, 

 536, 538, 541, 542, 543, 547, 548, 549, 550, 551 

 of man, 564-579, 565, 567, 569, 570, 571, 572 

 significance of fossils in, 530, 540-542, 543-544 

 summary of, 561; tlieories of, 555-563 



Excavating, for fossils, 530, 567 



Excretion, 125, 237-245; and typhoid, 327 



Excretory organs, 238 



Exercise, and blood movement, 218; and lymph 

 movement, 221 



604 



