I might just as well have said that a cactus without thorns is the normal cactus in the conditions where it was desired to obtain a succulent plant useful as food for cattle. The words “normal” and “physiological” seemed to me more convenient than such a phrase as “in correspondence with human ideals.” I am so little convinced of the existence of any disposition of nature to transform our ills into goods, and our disharmonies into harmonies, that it would not surprise me if such an ideal were never reached. Even in unmetaphysical circles it is said that nature has the intention of preserving the species at the expense of the individual. The ground of this is that the species survives the individual. On the other hand, very many species have completely disappeared. Amongst these species were animals very highly organised, such as some anthropoid apes (_Dryopithecus_, etc.). As nature has not spared these, how can we be certain that she is not ready to deal with the human race in the same way. It is impossible for us to know the unknown, its plans and motives. We must leave nature on one side and concern ourselves with what is more congruous with our intelligence. Our intelligence informs us that man is capable of much, and for this reason we hope that he may be able to modify his own nature and transform his disharmonies into harmonies. It is only human will that can attain this ideal. FOOTNOTES: [1] Westergaard, _Mortalitaet u. Morbilitaet_, 2nd. Edit., 1901, pp. 653-655. [2] The volume of the urine excreted in 24 hours (in January 1905) was 500 c.c., with a density of 1019. There was no albumen or sugar. The quantity, per litre, of urea was 11·50 gr., of chlorides 9 gr., of phosphates 1·15 gr. The sediment contained crystals of uric acid, some pavement epithelium cells, a very few cells from the tubules, some hyaline platelets and isolated white corpuscles. [3] _Extinct Animals_, London, 1905, pp. 28, 29. [4] _Rendiconti d. Accad. d. Lincei_, 1906, vol. xiv. pp. 351, 390. [5] _Ueb. d. physiologische Degeneration bei Actinosphærium eichhornii._ Jena, 1904. [6] “Senescence and Rejuvenation,” _Journal of Physiology_, 1891, t. xii. [7] _Biologisches Centralblatt_, 1904, pp. 65, 81, 113. [8] _Comptes rendus de l’Académie des sciences_, 23 April, 1900. [9] _Revue générale des sciences_, 30 Dec., 1904, p. 1116. [10] _Le Bulletin médical_, 1906, p. 721; _Le Cerveau sénile_, Lille, 1906, pp. 64-69. [11] _Mémoires couronnés publiés par l’Académie royale de Belgique_, Bruxelles, 1906. [12] _Revue de Médecine_, Nov., 1906, p. 870. [13] _Annales de l’Institut Pasteur_, Oct. 1906, p. 859. [14] _Annales de l’Institut Pasteur_, 1900, vol. xiv. p. 113. [15] _Eléments d’histologie humaine_, French translation, 1856, p. 222. [16] _Leçons sur la physiologie du système nerveux_, 1866. [17] _De la dégenérescence graisseuse des muscles chez des vieillards._ Paris, 1867. [18] Demange, _Étude sur la vieillesse_, 1886, p. 118.