210 ENDOCRINE GLANDS 



this ligation is followed after a few months by an atrophy 

 of the seminal tubules, while the interstitial cells remain 

 normal. Similar observations have been made by Bouin 

 and Ancel following the injection of zinc chloride in the 

 head of the epididymis and in man after gonorrheal or 

 tuberculous epididymitis. 



The exposure of the testicle to the X-rays causes the 

 disappearance of the seminal cells, but does not affect 

 the interstitial ones (Bergonie, Tribondeau, Villemin and 

 Regaud). These animals retain their genital attributes and 

 instincts. They cannot reproduce, but are not impotent. 



Inversely, the destruction of the interstitial gland, 

 which has been accomplished by Ancel and. Boiun in 

 young rabbits, after ligation of the spermatic artery and 

 venous plexus, caused an arrest of development of the 

 sexual characteristics. 



It is the study of castration in animals which gives the 

 most important demonstration of the action of the testic- 

 ular internal secretion on growth and the development of 

 the sexual characteristics. 



Animals castrated when they are young, before tney 

 have acquired their definite form, have an arrested 

 development. The distinct characteristics of the male 

 sex do not appear. The subject develops an exterior 

 appearance which resembles the female. The features 

 stay refined and the body is less developed. 



The skeleton shows a notable elongation: castrated 

 animals are larger than the controls. The growth is 

 chiefly of the posterior limbs and is due to the persistence 

 of cartilage beyond the normal period. 



The external genitalia show a more or less important 

 arrest of development, depending on the species, but it 

 is always noticeable. The experiments on dogs by 

 Guyon, Legneu and Albarran have shown that cas- 



