484 INTERNAL SECRETIONS 



erotization occurs in both parents ; first, because an individual 

 who is normal in this respect, will have a better chance of 

 choosing for a mate another individual who is sexually normal 

 in every respect ; secondly, because an individual who is normal 

 in this way is likely to produce normal generative cells, and 

 to have a somatic constitution such as is necessary for normal 

 uterine development, normal parturition and normal nutrition 

 of the progeny. But the occurrence of normal erotization, 

 sex characters, and possibly generative cells, depends on a 

 normal production of sex hormones. 



There is still another aspect of our problem which bears 

 on the science of eugenics. The question has often been 

 discussed as to how temporary or permanent sterilization can 

 best be practized from a social standpoint ; ligature of the vasa 

 deferentia has been done upon men for this purpose in Switzer- 

 land and in America; for the women irradiation with X-rays 

 has been suggested. Pearl's paper (1919) may be referred to 

 in this connection. 



The question of sex hormones is of interest also in relation to 

 veterinary medicine and '' zootechnics/* Many of those patho- 

 logical conditions referred to in man in connection with the 

 sex hormones may be observed also in the domestic animals. 



Another matter of great practical interest is that of the 

 possible utility of ovarian and testicular transplantation in 

 man in cases of hormonic deficiency. Much depends on whether 

 it will be possible in future to use glands of other species of 

 mammals for transplantation. Since sex hormones probably do 

 not have a '^species specifity," it is a question not of theory but 

 of practice. The papers of Voronoff (1923) and Thorek (1922) 

 on transplantation of apes' testicles in man seem to indicate 

 that a practical solution to the question is on its way. Voronoff 

 (1924) lastly gave an account of 43 cases of heterotransplanta- 

 tion in man, Thorek (1923) of 97 cases. As to autotransplanta- 

 tion of testicle and ovary there is, I think, no surgical prac- 

 titioner in this field to-day who does not appreciate its utihty. 



The practice of irradiation of the sex gland in men and 

 women is also one of practical interest. So also are the 

 questions relating to the injection of extracts, though, as already 

 remarked in Chapter VII., we are still a long way from their 

 solution. 



In recent years there has been much discussion concerning 



