Heberden’s nodes, 155 Height, cause of loss of, 100 Hereditary tendencies, correction of, 34 Heredity, firstlings in relation to, 38 influence on longevity, 19, 32–39 Hernia, tendency to, 153 Herpes zoster, 142 Hertoghe, 113 Hetero-suggestion, 48 High altitudes, influence on longevity, 39 Hippocrates, age of, 52 Holland, Henry, 28 Holmes, O. W., 49 Hopkins, G., 13 Hot climates, influence of, on senescence, 26, 36, 39 Huchard, 59, 105 Hufeland, C. W., 17, 23, 70 Humphry, G. M., 8, 22, 32, 34, 39, 43, 58, 60, 87, 98–100, 112, 124 Hunter, W., 124 Huxley, J. S., 11 Hygiene of old age, 55–61 Hyperpiesia, 37, 124 Hypertrichosis, following the menopause, 96 Hypnotics, 128 Hypochondriasis, 121 Hypoplasia, 63, 64 Hypothyroidism, in relation to old age, 72 Idleness, inimical to old age, 46, 47 Individuation, phenomenon of, 10 Infant mortality, sex incidence and causes, 22 Infantilism, premature senility with, 31 Infections, 140 cell changes due to, 43, 44 disposition to cardiac failure during, 149 focal, tendency to, 155 gout in relation to, 154 Insomnia, 119 Interstitial cells, 73–81 Intestinal stasis, as cause of premature old age, 82, 85 Intoxications, cause of senescence, 82 influence on body cells, 44, 55 Invalidism, auto- and hetero-suggestion producing, 48 Ireland, centenarians in, 40 Iris, sluggish, 117 Iverex, Dr., centenarian, 32 Jackson, Christopher, 3 Jackson, Hughlings, 122 James, R. R., 52 Jastrow, M., 130 Jaw, changes in shape of, 99 tremor of, 144 Jenkins, Henry, centenarian, 20 Jews, longevity of, 40 Johnson, S., 46 Joints, fractures of, disposition to, 99 Keratosis, senile, 143 Kidneys, 126 degenerative changes in, 111 granular, age incidence of, 140 King, G., 20 Klotz, O., 107 Knee-jerk, 119 Koheleth, 139 Kuntz, A., 74 Labyrinthine deafness, 118 Labyrinthine vertigo, 143 Lacassagne, A., 30, 55 Lane, W. Arbuthnot, 84 Lankester, E. Ray, 14, 19, 23 Laryngeal cartilage, calcification of, 100 Laurent, O., 41, 87 Laurentius, Andreas, 29, 46, 116, 131 Lazarus, 59 Lazarus-Barlow, W. S., 86 Leclercq, A., 140 Léri, 83, 146 Leroux, 103, 148 Lessius, Leonardus, 55 Leucocyte count, 108, 109 Leucodermia, 93 Leukaemia, 141 Leydig, interstitial cells of, 73–81 Lichtenstern, 77 Life, animal and human, duration of, 17, 18 chronometry of, 138 climacterics of, 27, 30 duration of, 9 among professional men, 50–53 chemical theory of, 66 early theories of, 17 estimation of, 18 _in vitro_, 66 various writers on, 17, 18 variation in different countries, 39 modern theories of, 18 expectation of, at birth, 13, 41 prolongation of, experimental, 12, 13, 77 following cessation of reproductive function, 23 _See also_ Longevity