Drives, fighting, 553 



Ductless glands, 302 ff. ; functions of, 306 f. 



Dunes, 19, 90 



Dust storm, 643 



Dusts, as occupational hazard, 636 



Dwarfism, 306, 310 



Ear, human, 289 



Eardrum, 15 



Earthworm, 208; tropisms of, 260; repro- 

 duction in, 388 



Echinoderms (e ki'no durmz), frontispiece, 

 693 



Ectoderm, 362 



Edentates, 698 



Education, 269, 430 



Effectors, 275 



Efferent nerve, 277, 282, 284 



Efficiency and fatigue, 223 



Egg, 125; fertilized, 348, 376; segmenta- 

 tion of, 361 



Eijkman, Christian (1850-1930), 106 



Electron microscope, 445 



Elements, necessary chemical, 97 fl. 



Elephant, 176, 698; brain of, 278 



Elliptical leaves, 43 



Embryo (em 'brio), of grain, 125; of ani- 

 mals, 349, 354 ; in flowering plant, 405 ; 

 in mammals, 423 f. 



Embryo sac, 402 



Emotion, organic sources of, 315 ff. 



Encephalitis (en sef a ll'tis), 445 



Endocrines (en'do krlnz), 296, 304 flf. 



Endoderm, 362 



Endosperm, 405 



Energy, of protoplasm, 83 ; air and, 84 ; 

 forms of, 85; required, 114 f.; unit of, 

 116 ; expenditure of, 118 flf. ; needs of, by 

 workers, 123; value of, from nutrients, 

 125; radiant, 138; hormones and release 

 of, 312 f. 



Enriched flour, 125 



Entire leaves, 43 



Environment, moisture in, 89; desiccated, 

 90; adjustments to, 269; and growth, 

 345 ; influence of, 357 f. ; limitations in, 

 533 



Enzymes (en'zlmz), 164, 169 



Epicotyl, 415 



Epidemics, 580 f . 



Epidermis (ep i dur'mis), 87, 141 , 144, 147, 21 7 



Epiglottis, 205 



Epinephrin (ep i nef'rin), 196, 307, 313, 

 314 



Epiphysis (e pif'i sis), 306 



Epithelial cells, 25, 348 



Eras, geologic, 451 



Ergograph, 223, 224, 225 



Ergosterol (er gos'ter ol), 110, 132 



Erosion, 154 



Esophagus, human, 166, 167; of bird, 173; 

 of lobster, 173 



Essential oils, 216 



Euglena (u gle'na), 687 



Evening primrose, mutations in, 511 



Evolution, 514 ff. ; classical views on, 448 



Excretion, in animals, 216 



Exopthalmic (ek sof thal'mik) goiter, 306, 

 312 



Exoskeletons, 101 



Eyes, of mammals, 14; of insect, 14 f . ; in- 

 vertebrate, 290 ; vertebrate, 290, 291 ; in 

 embyro, 363 



Facial features 13, 63 



"Fairy ring", 587 



Fallopian tube, 380 



Family, 38, 430, 668 



Family tree, of plants and animals, frontis- 

 piece 



Fat glands, 217 



Fat-soluble vitamins, 132 



Fatigue, 222 ff. 



Fats, 98, 125 ; energy value of, 125 ; test for, 

 183 



Fauna (fo'nfl), of prairie, 78; of swamp, 78 



Fear, 317 



Feces (fe'sez), 171 



Feelers, 14 



Fehling solution, 183 



Ferments, 164 



Ferns, 385, 690 ; life cycle of, 387, 412 



Fertilization, 376, 403 ; in flower, 404 ff. 



Fertilizer, excess of, 87 



Fetus (fe't«s), appendix of, 175 



Fibrin (fl'brin), 187 



Fibrovascular bundles, 91, 141, 144 



Filaments, 400 



Fingerprints, 73 



Fish, 32, 695 f. ; digestive system of, 173; 

 breathing of, 210; heart of, 210 



Fitness, 20 ; meaning of , 546 



709 



