INTERNAL SECRETION OF TESTICLE 175 



make it clear that, in my judgment, all the statements based on 

 "definite" proofs that the interstitial cells have nothing to do 

 with the internal secretion of the testicle, and that they are 

 nothing else than a nutritive organ for the seminal tubules, 

 are without any foundation. 



8. The Phases of Puberty in the Male. 



It is generally assumed that " puberty" marks the time when 

 a developmental process takes place in the organism of a 

 different kind from that going on previously. But in reality it 

 is not so. At the time of puberty we have only an acceleration 

 of processes culminating in the full development of the sexual 

 characters. Such a suggestion will be especially acceptable 

 if one takes into consideration the fact that the development 

 of the sexual characters, as we must now assume, has begun 

 already during embryonic life. The first steps towards sexual 

 maturity are made in the embryo; maturity is consummated 

 at the time known as puberty in the ordinary sense of the word. 

 In man and other mammals there is from birth to puberty a 

 relatively long period when the development towards sexual 

 maturity proceeds very slowly, or even for a time ceases 

 altogether. I showed experimentally with rabbits that in all 

 probabihty no internal secretion of the testicle is produced at 

 all for about three months after birth, the development of the 

 penis in the rabbit prepuberally castrated at an age of one to 

 two months being, until the commencement of the time when 

 puberty would otherwise occur, exactly like that in the normal 

 animal. So one may suppose that there are in reality two great 

 phases of puberty; the first at a certain time of embryonic 

 development, the second one several months (rabbit) or years 

 (man) after birth, and that these two great phases or climaxes of 

 puberty are separated b}/ an intermediate phase. Such an 

 assumption is necessary to the theory of the existence of an 

 asexual or indifferent state of the somatic substratum of the 

 sexual characters before the internal secretion of the gonads 

 enters into activity. 



We must now ask ourselves whether we have any knowledge 

 of the condition of the testicle at the indicated phases, so as to 

 explain the true correlation of the latter with corresponding 

 changes in the endocrine function of the testicle. As we have 

 seen at the beginning of this chapter, the interstitial cells seem 



