CHAPTER LIIL 

 PHYSIOLOGY OF THE MALE REPRODUCTIVE ORGANS, 



Puberty. — The sexual life of the male is longer than that of the 

 female. Puberty or sexual maturity begins somewhat later, — in 

 temperate climates at about the fifteenth year; but there is no dis- 

 tinct limitation of the reproductive powers in old age correspond- 

 ing to the menopause of the female. At the time of puberty and 

 for a short preceding period the boy grows more rapidly in stature 

 and weight, and the assumption of its complete functions by the 

 testis exerts a general influence upon the organism as a whole. 

 One of the superficial changes at this period which is very evident 

 i>-- t,he alteration in pitch of the voice. Owing to the rapid growth 

 ot ihe larynx and the vocal cords the voice becomes markedly 

 deeper, and the change is in some cases sufficiently sudden to cause 

 the well-known phenomenon of the breaking of the voice. The 

 neuromuscular control of the vocal cords becomes for a time un- 

 certain. The completion of puberty can not be determined in the 

 boy with the same exactness as in the girl, in whom menstruation 

 furnishes a visible sign of sexual maturity. Part of the sexual 

 mechanism may be functional long before the time of puberty, 

 as is shown by the presence of sexual desire and the possibility 

 of erection; but fully developed spermatozoa are not produced 

 until this period, and indeed the presence of ripe and functional 

 spermatozoa in the testis is the only certain sign that sexual ma- 

 turity has been attained. Puberty as thus defined consists in the 

 maturation of the testis in the male, and of the ovary in the female. 



It will be recalled that in the interesting work upon the internal 

 secretion of the testes reported by Steinach (p. 883) he empha- 

 sizes the fact that these organs consist of two distinct parts, the 

 reproductive cells proper lining the seminiferous tubules and the 

 interstitial tissue. This latter tissue forms the internal secretion, 

 which is responsible in all probabihty for the development of the 

 secondary sexual characteristics, such as the enlargement of the 

 penis and its accessory glands (vesicles, prostate), the appearance 

 of sexual desire, the prepubertal growth, etc. Since the full devel- 

 opment of these characteristics marks the appearance of puberty, 

 Steinach proposes to designate the mass of interstitial tissue as the 

 "pubertal gland." Normally, the full establishment of the sex 



