Osteomalacia, senile, 139 Osteoporosis, senile, 99 Ovarian extract, rejuvenescence in relation to, 80 Ovaries, activity and function of cells of, 73, 74 degenerative changes in, 114 fibrotic atrophy of, 63 following menopause, 79 in relation to senescence, 75 internal secretion of, evidence of existence of, 79 senile, 114 Over-eating, 56, 118 Overwork, danger of, 54 Owen, I., 57 Paget, James, 36, 138 Paget’s disease of bone, 156 Pain, blunting of sensibility to, 117 Pallor, 93 Pancreas, fibrotic atrophy of, 102 Paralysis agitans, 144 age and sex incidence of, 144 causes of, 144 senile tremor compared with, 143 Paraplegia, senile, 138, 146 causes of, 146, 147 varieties of, 147 Parathyroids, 110 Parietal bones, changes in, 100 Parkinsonian syndrome, 144 Parr, Thomas, centenarian, 20 Pathological old age, 53, 82, 90 Patriarchal ages, length of the calendar during, 16 Patriarchs, explanation of reputed old age of, 15, 16 Pearson, K., 38, 86 Pecten band, 152, 153 Penis, changes in, 114 Pennington, Isaac, 6 Peristalsis, failure of, 152 Philalethes, Eugenius, on old age, 15 Phlebitis, 151 Phlebosclerosis, 107 Physical and mental states, want of harmony between, 123 Physiological life of man, 19 Physiological old age, 90 and morbid senility, distinction between, 135–138 Physiology of old age, 115–128 Pigmentation, cellular, 103 cutaneous, 93 Piles, 153 Pitman, Henry, medical centenarian, 52 Pituitary extract, influence on weight and growth, 12 rejuvenescence in relation to, 12, 80 Pityriasis versicolor, 141 Planarian flat worms, experimental modification of life cycle and growth of, 11 Plasma, vital phenomena of, 65–67, 88 Plethora, senile, 124 Pneumonia, 147, 148 disposition to, 140 sudden death from, 117 Premature senility, 30 causes of, 48 hot climates predisposing to, 26, 36 syphilis producing, 45 Presbyopia, 117 Pringle, J. J., 94 Prior, Matthew, 3 Professional men, age of retirement of, 54 longevity of, 50–54 Progeria, 30 Prostate gland, 27 _climacterium virile_ due to changes in, 27 hypertrophy of, 101, 112 age incidence of, 140 cause of, 112 cell changes in, 112, 113 glandular therapy of, 113 vesical disorders due to, 153 senile changes in, 111 Protoplasm, products inimical to vitality of, 65 vital phenomena of, 64, 65, 88 Protozoa, rejuvenation and senescence in, 9–11 Prurigo, senile, 141 Pruritus, senile, 141, 142 Pseudo-paraplegia, 146 Psychical activity, diminished, 119 Psychical fatigue, 122 Puberty, functional activity of cells of testes and ovaries at, 75 period of, 17 “Puberty gland,” 73 Puerilism, 122, 145 Pulmonary changes, 103, 147 Pulmonary tuberculosis, 148 Pulse-pressure, 125 Pulse-rate, 124