Hygiene, individual, ideals implied by, 1; medieval views contrasted with modern ideals, 1-2; good, ventilation the first rule, of, 7; mental, 105-118; unity of, 121-126; obstacles to, 126-135; possibilities of, 135-143; and civilization, 143-156; public versus individual, 157-159; necessity for cooperation between public and individual, 159-161; race, 163-168; of immediate concern to the present generation, while eugenics is important for future generations, 167-168. Hypochondriacs, risk of becoming, 111. Ice-cream, comparative food value of, 33. Ideal food proportions, 173. Ideals, of individual hygiene, 1; contrast afforded by medieval, 1-2; present-day establishment of more wholesome, 2; as to labor, 3-4; still further improvement needed in American, 4-6. Idleness, evils of, 91. Impairments, unsuspected physical, 136-139. Inactivity, necessity for periods of, 89; rest and sleep the two great forms of, 89. Indians, bad effects of indoor living upon, 146-147. Indigestible foods, digestibility of so-called, 49. Individual hygiene, public hygiene versus, 157-159; practice of, a remedy for degenerative tendencies, 292. Indoor living, unnatural character and evils of, 145-147. Industrial workers, unsuspected impairments among, 137-138; calories of food consumed daily by different classes of, 195; powers of, lessened by use of alcohol, 238, 244. Infections of the body, by germs, 69-75; importance of cleanliness for avoiding, 75; through the mouth, 78-83; in colds, 272. Infectious diseases, power of resistance to, weakened by alcohol, 68; results regarding, from teeth hygiene, 88. Insect-borne diseases, 71. Insomnia, remedial measures for, 102-103; often caused by excessive smoking, 264. Instinctive eating, experiments with, 200-209. Intestinal intoxication, distinguished from autointoxication, 81-82. Intestinal poisoning, from insufficient mastication, 45. Introspection, one of the curses of idleness, 91. Iron, in vegetable foods, 40. Italy, mortality statistics of, 286. James, William, on enjoyment of life, 5; on religion of healthy-mindedness, 114. Jews, effects of indoor living withstood by, 147. Kidney, among the worst foods, 48. Kidneys, death rates from diseases of, 284, 285. Kipling, Rudyard, on concentrated foods, 41-42. Labor, modern ideals concerning, 3-4; turned from drudgery into play by proper development of health ideals, 5-6; division of, an evil of civilization, 152. _See_ Work. Lamb, food value of, 29, 178. Laxative drugs, avoidance of, 53. Laxative foods, 52. Leg-lifting exercise for faulty posture, 222. Lettuce, cellulose in, 41; vitamins supplied by, 42; food value of, 175. Lice, diseases carried by, 74-75.