Pohl, Dr., on growth of hair, 17, 18 _Ponogenes_, as cause of sleep, 120 Potatoes, improved by Burbank, 326 Poushkin, 236 Predestination, and plants, 103 Preyer, Dr., on _Ponogenes_, 120 Prichard, on longevity of negroes, 88 Productivity compared with fecundity, 57, 58 Prostokwacha, 172, 176 Prolongation of life, 132 _et seq._ Prothalli, life of, 99 Psychids, death of, 117 Ptolemy, fear of Hegesias’ philosophy, 235 Punishment, capital, 305 Purgatives, use of, in intestinal putrefaction, 157 Putrefaction, intestinal, 151 _et seq._, 161, 163, 164 Quételet, on stature of the aged, 9 Rabbit, fecundity of, 58 Ravens, absence of putrefaction in intestines of, 75 Reagents, action of, in distorting tissues, 20 Renouvier, C., on his own death, 127 Reproduction, organs of, rudiments in, 189 Reptiles, longevity of, 50 Rhea, cæca of, 60, 77 Rhinoceros, longevity of, 54 _Rhytina_, 213 Riley, James, on food of Arabs, 174 Rimpau, on cultivation of rye, 326, 328 Rist and Khoury, on milk, 178 Rist, M., on ferment of Egyptian milk, 105 Rivière, M., on defecation in ostriches, 76, 78, 79 Robineau, Mde., 5, 6, 7, 8, 128, 159 “_Roman Elegies_,” Goethe’s, 268, 273 Rotifera, duration of life, 39 death of, 112 Roux, anti-syphilitic ointment, 146 Rovighi, on Kephir, 173 Rudimentary organs, 185 _et seq._ Rye, duration of life of, 100 Rimpau’s improvement of, 326 Salpétrière, hysterical patients at, 201 old women in the, 4, 5 Sand, M., on senile brain, 20 Sargent, on age of Sequoia, 98 Sauer-kraut, 165, 171 Sauvage, M., on atheroma, 30 Savage, on character of anthropoids, 193 Saxe-Weimar, Grand Duke of, and Goethe, 274 Schaudinn, spirillum of syphilis, 31 Schiller, Goethe on, 271 Schiller, on moral conduct, 310 Schlanstedt, rye of, 326 Schmidt, on microbes in constipation, 70 Schopenhauer, 235, 247, 255, 277, 330 Schumann, a degenerate, 134 Science, and morality, 301 _et seq._ Sclerosis, in the aged, 31 Sea-anemones, longevity of, 47, 48 Sea-cow, 213 Selection, medical, 134 Seneca, 132, 235 Senescence, Brown-Séquard’s specific against, 139 mechanism of, 25 phagocytosis as cause of, 35 Senility, characters of, 8, 14 and digestive system, 59 theories of causation of, 15 _et seq._ Sensation, analysis of, with regard to pain and pleasure, 243 Sense of life, 26 of obstacles, 258 Sense, organs of, rudimentary structures in, 186, 187 “Sermon on the Mount,” 321 Serums, cytotoxic, 147, 148, 149 Servants, care of, 321 Sex, and longevity, 57 Sexuality, Goethe and, 273 _et seq._ and old age, 276 moral problems of, 305 Sexual organs, abnormalities of, 224 Sexual power and genius, 272 Shakespeare, quotations, 239, 307 Sheep, digestion of, 74 longevity, 55 Sight, rudimentary organs of, 189 Silos, 165 Siphonophora, 217