Fertility and longevity, 44, 45 Fish, longevity of, 50 Flamans, M., 5 Fletcher, on chewing, 159 Flora, of intestines, poisonous effect of, 70, 73 _et seq._, 151 _et seq._ Flourens, on duration of life, 40, 84 Foà, on use of soured milk in Africa, 172 Food, evil effects of putrefaction in, 163 Fouard, M., on soured milk, 180 Fürbbinger, on Brown-Séquard’s emulsions, 139 Gautier, A., on leucomaines, 121 Gegenbaur, on intestinal tract, 60, 61 Genius and sexual power, 272 Gerokomy, 136 Gessner, on age of pike, 50 Gestation and longevity, 42 Giacomini, on Harderian gland, 189 Gibbons, 192, 198 Goebel, on duration of life of prothalli, 101, 102 Goethe, 260-300, 305 “Goose-skin,” 196 Gorilla, strength of, 192 Griesbach, on sense of touch in blind, 257 Grigoroff, on Bulgarian yahourth, 175, 178 Grindon, on age of sheep, 55 Guinon, Dr., on a case of hysteria, 203 Gurney, J. H., on longevity of birds, 51, 79 Haeckel, on medical selection, 134 Haffkine, M., 112 Hair, 17, 18 _Halictus_, a solitary bee, 226 Haller, on human longevity, 84, 132 _Hamlet_, quotation from, 239 Hannibal, his elephants swim the Rhone, 197 Harderian gland, 189 Hartmann, 235, 241 Harvey, on Parr, 87 Hayem, Prof., on use of lactic acid, 169, 173 Heart, diseases of, and syphilis, 145, 146 Hegesias, and suicide, 234 Heile, on absorption in colon, 64 Heim, on microbes in milk, 176 Heim, Prof., on Alpine accidents, 130 Heine, 236, 240 Hermippus, and gerokomy, 137 Herter, Dr., experiments on lactic acid in dogs, 167 Hertwig, R., on _Actinosphærium_, 14 Hildebrand, on duration of life of plants, 101, 102 Hippocrates, 132 Hofmeister, on digestion in horse, 74 Honey-ant, 222 Horse, cæcum, 62 digestion, 74 use of serum, 147 Horsley, Sir V., on effects of extirpation of thyroid, 34 Horst, on a somnambulistic soldier, 203 Hufeland, quotation from “Macrobiotique,” 137 Hugo, V., and sexuality, 277 Humboldt, on dragon-tree of Orotava, 96 on longevity of parrots, 52 Hunger, compared with sleep, 125 Huxley, on character of Orang, 193 Hygiene, and old age, 141, 142, 143 Hypnotism, of a crowd on individuals, 210 Hysteria, analysis of, 200 _et seq._ in monkeys, 208 Ibsen, and sexuality, 277 Idleness, 316 Immortality, Chinese beverage for, 137, 138 Incubation, duration of, compared with longevity, 41, 42 India, government of, and age of elephants, 54 Individualism, 316 Individuality, 212 _et seq._ Infusoria, death of, 95 senescence of, 13 Insects, ages of, 49 social, 220 _et seq._ Instinct, of death, 128, 129 maternal, 319, 320, 329 social, 306 Intestine, large, 59, 65, 67, 151 Intuitive theory of morality, 305 Jacobson, organ of, 187 Javal, Dr., on characters of the blind, 257, 259 Jenner, effect of vaccination on mortality rate, 144