INDEX 



439 



Heredity, work of Gregor Mendel, 



386, 387, 388, 389. 

 Hermit crab, symbiosis, 105. 

 Herring, 352, 372. 

 Hibernation, 17. 

 Hilum, 52. 



Hodge, Professor, cited, 298. 

 Home surroundings, 293-297. 

 Homology, 237. 

 Honey, 351. 

 Honeybees, 26, 351. 

 Hooke, Robert, biologist, 44. 

 Hookworm, 289, 290. 

 Hormones, 148, 166, 167, 168. 

 Hornaday, Dr., on birds, 375, 377. 

 Home, Professor, rules for habits, 211. 

 Horses, 391. 



Host, of a parasite, 31, 287. 

 House fly, 283-285. 

 Human machine, 112; see Body. 

 Human race, 251; 



improvement of, 394. 

 Humidity of air, 184. 

 Humming birds, polhnation by, 38, 39. 

 Humus, 10, 64. 



Hundred-calorie portions, 135. 

 Huxley, Thomas Henry, biologist, 



405, 412. 

 Hybridizing, 386-389. 

 Hybrids, 386-389. 

 Hydra, 108, 109, 111; 



symbiosis, 105. 

 Hydrochloric acid, in digestion, 153, 



154. 

 Hydrogen, in water, 8, 9. 

 Hydrophobia, 274. 

 Hydrotropism, 16. 

 Hygiene, 1,22; 



of breathing, 181, 184 ; 



of mouth, 151 ; 



of muscles and bones, 114, 115; 



of skin, 112-113; 



pubhc, 308 ; 



school and infant, 310, 311. 

 Hymenoptera, 26, 242. 

 Hypocotyl, 52. 



Ice, use in home, 296. 



Ice cream, bacteria in, 298. 



Ichneumon fly, 358. 



Iguana, 352. 



Imago, 230. 



Imbibition, of root hairs, 71. 



Immunity, 270; 



acquired, 271 ; 



active, 272, 274-276; 



passive, 272, 273. 

 Imperfect flowers, 39. 

 Incinerator, 307. 

 Incubation period, 269, 270. 

 Infantile paralysis, 269. 

 Infection, of wounds, 113. 

 Infectious disease, 254, 261-286. 

 Influenza, 264, 268, 295. 

 Infusoria, 239. 



Inheritable characters, 397, 401. 

 Inoculation, 274, 275. 

 Inorganic soil, 64. 

 Insecta, 242. 

 Insectivora, 249. 

 Insects, 25; 



classification, 242; 



eaten by birds, 359; 



enemies of forest, 319; 



eyes, 26, 33 ; 



feed on plants, 30 ; 



harmful, 295, 362-365; 



instincts, 209; 



relation to flowers, 31, 33, 34-39; 



sense of smell, 34 ; 



sense organs, 196 ; 



useful, 357; 



see also names of insects. 

 Inspection, of factories, etc., 298-299 ; 



of food suppHes, 299-301. 

 Instincts, 208. 

 Insulin, 168. 

 Intestinal fluid, 157. 

 Intestine, 157, 158, 159; 



large, 159. 

 Invertebrates, 243. 

 Iodine, 260. 

 Iris, 205. 

 Irrigation, 313. 



Irritability, of protoplasm, 192. 

 Ivory, 355. 



James, William, quoted, 211. 

 Jenner, Edward, 271, 274. 

 life, 407, 408. 



