Weber, Dr., on regimen for old age, 140, 141 Weichardt, on cause of fatigue, 122, 123 Weinberg, Dr., on preparation of human serums, 150 on thyroid gland in aged, 33 Weiske, on digestion in sheep, 78 Weismann, A., on cause of old age, 15, 16 on death in infusoria, 95 on duration of life, 41, 43, 45, 51 “Weltschmerz,” in German poetry, 236 _Werther_, Goethe’s, 263, 267 Westergaard, statistics of mortality, 142, 144 Wiedersheim, on intestinal tract, 60 Wine, Goethe and, 271, 279 Wolff, J. H., Goethe’s friend, 271 Women, education, 224 _et seq._ Yahourth, use in intestinal putrefaction, 168, 170, 175, 177, 178 Yeast, conditions of growth, 106 Zeigan, Dr., on adrenaline, 122 Zell, Dr., on blind persons, 259 Zelter, Goethe’s friend, 265 Zola, “La Joie de Vivre,” 248 Zoological Gardens of London, 51, 81 Zortay, Pierre, age of, 87 End of Project Gutenberg's The Prolongation of Life, by Elie Metchnikoff