Mind, 121 and body, in old age, 47, 50 disintegration of, 120 disorders of, 122, 145, 146 _See also_ Mental Molière, 53 Mönckeberg’s sclerosis, 106 causes of, 142 Montaigne, 14, 56 Moon, R. O., 136 Moore, Norman, 5 Morbus coxae senilis, 155 Morphine, 127, 128 Mott, F. W., on functions of cells of testes and ovaries, 75 Muscles, voluntary, changes in, 103 Muscular activity, danger of excess of, 54 impaired, 99, 119, 135 Muscular atrophy, 99, 119, 135 among workmen, 54 Myocardium, degeneration of, 104, 149 Myxoedema, as secondary senilism, 72 Nails, condition and appearance of, 96 Nanism, senile type of, 31 Nascher, I. L., 30, 98, 127 Nathan, 68, 74 National habits, influence on longevity, 40 Natural death. _See_ Death Neck, senile tremor of, 143 Nemenow, 112 Nephropathy, chronic atrophic, 111 Nerves, cutaneous exposure of, 141 Nervous apprehension, tendency to, 122 Nervous disease, 145 Nervous system, 38 vitality of, hereditary factor in longevity, 36 Neurasthenia, 122 New growths, rarity of, 87, 89 Newton, Isaac, 53 Nicotine, effects of, 59 Nunneley, F. P., 151 Obesity, 60 Occupational neuroses, 54 Octogenarians, among active professional men, 51 census statistics of, 21 Oertel, H., 88 Old age, acceleration of, factors favouring, 26 anatomical and physiological changes in, 63 as a disease, 47, 136 attainment of, on what dependent, 6, 7, 10 biochemistry of, 64–68 biological aspect of, 10, 11, 23 bodily conformation in, 60 causes of, 62–89 cell changes leading to, 64, 65 “cell-memory” in relation to, 35 comparative freedom from chronic disease in, 44 death during, common causes of, 38 disabilities of, 137 disease in relation to, 44 diseases associated with, 93–114, 139–156 fertility rate in relation to, 23, 24, 26 glandular, endocrine, theory of, 70, 71, 81 healthy and morbid, distinction between, 135 hereditary aspects of, 32–39 hygiene of, 55–61 infantilism and, 31 mental activity during, 50, 54 examples of, 50, 51, 53 natural death from, 14 on what dependent, 10 onset of, 26 signs of, 29 pathological, 30, 82, 90 of septuagenarians, 53 physiological, 26, 90, 135 physiological and pathological confusion between, 90 factors in, 26 physiology of, 115 premature, 30 hot climates favouring, 26, 36 intestinal stasis as a cause of, 85 mental causes of, 48, 49 production of, Metchnikoff’s theory, 83 rarity of natural death from, 14, 91 sex incidence of, 21, 22 stages of, 29 vitality of body cells in, 62–68 writers on, 8, 15, 16 _See also_ Senescence; Longevity Onychogryphosis, 96 Ophülz, W., 105 Oral sepsis, 44, 155 Orthobiosis, 55, 84 Osler, W., 2, 36, 151 Osteitis deformans, 156