24 INTERNAL SECRETIONS 



prepuberal castration. Although the penis continues to grow 

 after prepuberal castration, it does not acquire the character- 

 istic shape of the normal penis. 



A careful investigation of the relations between the testicle 

 and the activity of the prostatic gland in the dog has been 

 made by Amantea (1919). 



D 



f 



; 



jgmn^^^ 





Fig. 15. — Influence of castration on the rabbit's penis. 



A. Normal, 2 months old. 



B. Normal, 12 months old. (Prot. Nr. 42). 



C. 12 months old, castrated when 2 months old (Prot, Nr. 43). 



D. 12 months old, castrated when 6 months old (Prot. Nr. 56). 



All these experiments show that normal development of the 

 genital organs is possible only when the sexual glands are 

 present in the organism. But I have mentioned already that 

 there is a diminution of the length of the horny styles also after 

 postpuberal castration in the guinea pig. An even more 

 striking instance of this kind is presented by observations 

 made on the penis of rabbits postpuberally castrated. ^At the 

 time of the operation the penis was fully developed, having 

 attained the characteristic shape of the normal adult animal; 



