Note 311 — Chapter IV

In Müller's Physiology, vol. ii. p. 1657, a work of great authority, it is said, that ‘the causes which determine the sex of the embryo are unknown, although it appears that the relative age of the parents has some influence over the sex of the offspring.’ That the relative age of the parents does affect the sex of their children, may, from the immense amount of evidence now collected, be considered almost certain; but M. Müller, instead of referring to physiological writers, ought to have mentioned that the statisticians, and not the physiologists, were the first to make this discovery. On this curious question, see Carpenter's Human Physiology, p. 746; Sadler's Law of Population, vol. ii. pp. 333, 336, 342; Journal of Statistical Society, vol. iii. pp. 263, 264. In regard to animals below man, we find from numerous experiments, that among sheep and horses the age of the parents ‘has a very great general influence upon the sex’ of the offspring. Elliotson's Physiology, pp. 708, 709; and see Cuvier, Progrès des Sciences Naturelles, vol. ii. p. 406. As to the relation between the origin of sex and the laws of arrested development, compare Geoffroy Saint-Hilaire, Hist. des Anomalies de l'Organisation, vol. ii. pp. 33, 34, 73, vol. iii. p. 278, with Lindley's Botany, vol. ii. p. 81. In Esquirol, Maladies Mentales, vol. i. p. 302, there is a singular case recorded by Lamotte, which would seem to connect this question with pathological phenomena, though it is uncertain whether the epilepsy was an effect or a cognate symptom.