MAMMALIAN SEXUAL CHARACTERS 153 



retained testes should always be sterile, witliout 

 spermatogenesis. If the inherited or congenital 

 process of dislocation requires the presence of 

 hormones produced by a normal testis, then we can 

 understand why a defective testis does not descend 

 completely, because it does not produce the hormone 

 which is necessary to stimulate the hereditary 

 mechanism to complete dislocation. It is often 

 stated that in cryptorchidic individuals the sexual 

 instincts and somatic sexual characters are well 

 developed, which would appear contradictory to the 

 above explanation, but according to Ancel and 

 Bouin such individuals in the case of the pig show 

 considerable differences in the secondary signs of sex 

 and in the external genital organs, presenting 

 variations which lie between the normal and the 

 castrated animal. 



We have here, then, in the position of the testes in 

 Mammalia a condition which is not in the slightest 

 degree ' adaptive ' in the ordinary sense — that is, 

 fulfilling any special function or utility. The 

 condition must be regarded as distinctly disad- 

 vantageous, since the organs are more exposed to 

 injury, and the abdominal wall is weakened, as we 

 know from the risk of scrotal hernia in man. But 

 from the Lamarckian point of view the facts support 

 the conclusion that the condition is the effect of 

 certain mechanical strains, and is of somatic origin, 

 while the correlations here reviewed are entireh' 

 unexplained by any theory of mutation or blasto- 

 genic origin. 



