40$ OF THE GROWTH AND DECREASE 



going various remarkable changes, is being gradually 

 prepared for the exercise of the sexual functions. 



655. Immediately after the period when the breasts 

 of the adolescent girl have begun to swell, the chin of 

 the boy is covered with down, and other phenomena of 

 approaching puberty manifest themselves in either sex. 

 The girl begins to menstruate (554), — an important 

 change in the female economy, accompanied, among 

 other circumstances, nearly always, by an increased 

 brightness of the eyes and redness of the lips and by 

 more evident sensible qualities of the perspiration. 

 The boy begins to secrete genuine semen (527), and, at 

 the same time, the beard * grows more abundantly, and 

 the voice becomes extremely grave. 



By the spontaneous internal voice of nature, as it 

 were, the sexual instinct (71) is now for the first time 

 excited, and man, being in the flower of his age, is ca- 

 pable of sexual connection. 



656. The period of puberty cannot be exactly defined : 

 it varies with climate and temperament, f but is gene- 

 rally more early in the female ; so that, in our climate, 

 girls arrive at puberty about the fifteenth year, and 

 young men, on the contrary, about the twentieth. (B) 



657. Soon after this, growth terminates; at various 



* The fabulous report that prevails even to this day, respecting the want of 

 beard among some American nations, I refuted by a host of witnesses in the 

 Gotting. Magaz. arm. ii. P. vi. p. 418 sq. For I have adduced instances from 

 the whole of America, both of nations who allow their beard to grow, at least, 

 in part ; and of others, who, upon indubitable authority, pluck out their beard 

 by peculiar instruments, &c. 



f I have inserted in the Bibl. Medic, vol. i. p. 558 sq. an account communi- 

 cated to me by G. E. ab Haller, of procreation in a Swiss girl only nine years 

 of age. 



