INDEX 



423 



Digested food, absorption of, 308. 

 Digestibility and diet, 281. 

 Digestion, 68, 100, 181 ; 



effect of alcohol, 311 ; 



definition of, 270 ; 



in stem, 99 ; 



in stomach, 304; 



of starch, 299 ; 



purpose of, 69, 296. 

 Digestive system of fish, 235. 

 Digestive tract of frog and man, 



297. 

 Diphtheria, 152. 

 Dipnoi, 187, 236. 

 Diptera, 31. 



Discoverers of living matter, 398. 

 Disease, and alcohol, 312 ; 



and bacteria, 151 ; 



carriers, animals, 226 ; . 



carriers, flies, 222 ; 



carriers, insects, 225 ; 



caused by bacteria, 152 ; 



caused by protozoa, 172 ; 



effect of alcohol, 327 ; 



of nose and throat, 340 ; 



protozoan, 221. 

 Disinfectants, 148. 

 Division of labor, 178, 267. 

 Dog, skeleton, 185. 

 Domesticated animals, 203, 260. 

 Dominant characters, 258. 

 Dormant, 22. 

 Dorsal, 186 ; 



fin, 233. 

 Drugs, use and abuse, 294. 

 Duff, 113. 



Dyspepsia, cause and prevention, 

 310. 



Ear, section, 359. 

 Echinoderms, 184. 

 Economic value of green plants, 117 ; 

 importance of spawning habits of 

 fishes, 239. 

 Ectoderm, 177. 

 Effect of light on leaves, 88. 

 Efficiency of a week, 370. 

 Egg, 177, 246. 

 Egg-laying habits of fishes, 238. 



Ehrlich, Paul, 403. 

 Elasmobranchs, 187. 

 Elements, chemical, 20, 21. 

 Elodea, 49, 50. 

 Embryo, 58, 59, 103 ; 



of bird, 247 ; 



of mammal, 247. 

 Emulsion, 306. 

 Endoderm, 177. 

 Endoskeleton, definition, 237. 

 Endosperm, 67. 

 Enemies of forests, 113, 114. 

 Energy, 64 ; 



of a tree, 94 ; 



source of, 88. 

 English sparrow, 212. 

 Environment, 19, 19 ; 



care and improvement of, 26 ; 



changes in, 25 ; 



determines kind of plants and 

 animals, 23, 23, 24; 



normal, 28 ; 



of man, 26, 266 ; 



natural, 25 ; 



relation to diet, 280 ; 



what plants and animals take 

 from, 21. 

 Enzymes, 68, 101, 298. 

 Epicotyl, 59. 

 Epidermis, 86. 

 Epithelial layer, 308. 

 Epithelium, 179. 

 Erosion, prevention of, 106, 108 ; 



at Sayre, Pa., 106. 

 Essential organs, 36. 

 Esophagus, 302. 

 Eugenics, 261. 

 Eustachian tubes, 300, 359. 

 Euthenics, 264. 

 Evaporation, 99 ; 



of water, 85, 86, 87. 

 Evolution, 194, 195. 

 Excretion, 181, 270, 332; 



organs of, 340 ; 



in plants, 103. 

 Exercise and circulation, 326 ; 



and health, 339. 

 Exoskeleton, 185, 237. 

 Extermination of birds, 211. 



