Colon, destruction of putrefactive bacteria in, 83 Constipation, 101, 152 age incidence of, 152 gerontal, 102 tendency to, 115 Cornaro, on the duration of life, 18 writer on old age, 8 Costal cartilage, calcification of, 100 Councilman, W. T., 37, 92, 104, 107, 111, 125 Cranial bones, changes in, 100 Crosby, T., 51 Cushny, A. R., 81 Cutaneous sensation, 117 Cystitis, 154 Darwin, C., 53 Deafness, causes of, 118 senile, 118 Death, causes of, 13, 38 mental attitude to, 123 natural, 13, 14, 16, 91 from old age, 14, 91 in animal kingdom, 13, 14 probable cause of, 36 Weissmann’s conception of, 9, 16 phenomenon of, 9, 10 sudden, causes of, 117 latent pneumonia causing, 148 Death-rate, in various countries, 42 sex incidence, 22 Deaths, among centenarians, 41 Decrepitude, 30 Delirium, 146 Delusions, 146 Demange, 91, 105 Dementia, senile, causes of, 146 onset of, 145 varied features of, 146 “de Morgan’s Spots,” 108 Dental decay, 101 an accompaniment of old age, 44, 45 Dentition, third, explanation of, 101 Depression, senile, 146 de Salis, Cardinal, centenarian, 50 Descartes, 7 Desmond, Countess of, centenarian, 20 Devolution, course of, 122 Diabetic gangrene, 142 Diet, restricted, influence of, 56 Digestion, impairment of, 101 Digestive system, 38 Disabilities of old age, 90–114, 137 Disease, associated with old age, 30, 44, 139 chronic, freedom from, in old age, 44 definition of, 136 influence of, on longevity, 43 latency of, 117 old age as a, 49, 136 Doctors, duration of life of, 52, 53 centenarian, 52 Donaldson, R., 110 Drew, A., 68 Drinkwater, H., 52 Drugs, reaction to, 127–128 reaction to, during senescence, 127 Dryness of elderly bodies, 64 Ductus cochleariae, fibrosis of, 118 Dupuytren’s contraction, 155 Dysbasia, functional, 146 Dyspepsia, frequency of, 152 Early rising, 59, 60 Ears, disorders of, 143 Easton, J., 20, 47 Ebstein, 18 Eccentricities of old age, 120, 121 Ecclesiastes, interpretation of, 129 Eczema, 118, 141 Emphysema, 147, 149 Endarteritis obliterans, 103 Endocrine glands, in relation to old age, 12, 68–81 Endomixis, 9 Environment, influence on longevity, 33, 34, 39–46, 55 Erysipelas, 141 disposition to, 140 senile, course of, 142 Erythema, 141 Eunuchs, duration of life of, 79 Expectation of life, 13, 41 in various countries, 42 Extra-systoles, 124 Eyes, senile disorders of, 117 Facial appearance, 93 changes in, 93 causes of, 118 Fads, 121 Faintness, 151 Fat, reduction of, 92 subcutaneous, disappearance of, 94 Fatigue, excessive, danger of, 54 physical and mental, 119, 120 psychical, 122 Fatty degeneration of arteries, 106 of heart, 104 of muscles, 103