226 Basis of Sex Determination 



the penis develops incompletely. Such animals when 

 adult recognize the female and seem to follow it, but 

 do not persist in their attention and neither erection 

 nor cohabitation occurs. When, however, the testes 

 are retransplanted into the muscles of the castrated 

 young animal (so that they are no longer connected 

 with their nerves) seminal vesicles, prostate, and penis 

 develop normally, and these animals show normal 

 sexual ardour and cohabitate with a female although the 

 female cannot become pregnant since the males cannot 

 ejaculate any sperm. When the retransplanted testes 

 were examined it was found that all the sperm cells 

 had perished, only the interstitial tissue of the testes 

 remaining. It was, therefore, proved that the develop- 

 ment of the seminal vesicles, the prostate, the penis, 

 and the normal sexual instincts and activities depends 

 upon the internal secretions from this interstitial tissue 

 and not upon the sex cells proper. This agrees with the 

 conclusions at which Bouin and Ancel had arrived by 

 ligaturing the vasa deferentia of male animals. 



Steinach in another series of experiments castrated 

 young male rats and transplanted into them the ovaries 

 of young females. These ovaries did not disintegrate, 

 the eggs remaining, and corpora lutea were formed. 

 In such feminized individuals the seminal vesicles, 

 prostate, and penis did not reach their normal develop- 

 ment, and it was thereby proved that the internal secre- 

 tions from the ovary do not promote the growth of the 



