Culex, 218, |218|. Culture medium, 140. Cuts and bruises, treatment, 326, 345. Daily calorie requirement, 282; fuel needs of body, 284. Dandelion, whorled leaves, |90|. Darwin, Charles, 40, 404. Darwin and natural selection, 253. Deaths, table, |312|. Decay caused by bacteria, 149. Decayed teeth, 396. Defects in eye, 361. Deforestation in China, |108|. Dendrites, 351. Department of Agriculture, work of, 255. Department of street cleaning, 387. Determiners, 251; of character, 258. Development, of apple, 56; of bird, 246; of egg, |178|; of trout, |238|; of mammal, 247; of salmon, |241|; of simple animal, 177. Diagram of frog's tongue, |242|; of gills of fish, |235|; of neuron, |351|; of wall small intestine, |307|. Diaphragm, 270, 297. Diastase, 101, 300; action on starch, 69. Diet, and cost of food, 281; and digestibility, 281; balanced, 285; relation of age, 280; relation of environment to, 280; relation to sex, 280; relation of work to, 277; the best, 284. Dietary, the best, 282. 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.