152 INTERNAL SECRETIONS 



increased action on the part of the puberty gland. As we have 

 already seen above, Ancel and Bouin have argued in the same 

 manner, when dealing with the proportion between the number 

 of the interstitial cells in the retained testicle and the develop- 

 ment of the sexual characters. Observations of Steinach 

 seemed to corroborate this. He records that several rats, in 

 which both transplanted testicles had "taken," showed an 

 abnormally great sexual activity. In other cases where the 

 engrafted testicle was diminished in size the sexual characters 

 were midway between those of a castrated and those of a 

 normal animal; the genital organs had continued their 

 development to a certain degree, but there was no sexual 

 activity. Thus, according to Steinach, the experiments with 

 transplanted testicles corroborate the view that the degree of 

 development of the sexual characters depends upon the degree 

 of development attained by the interstitial tissue. A series 

 of experiments with transplantation performed by Sand 

 (1918, pp. 74-95) on rats seemed to give further evidence for a 

 proportionality existing between the number of interstitial 

 cells and the degree of development of the sexual characters. 

 When in the transplanted testicle only a few interstitial cells 

 were present, the animals developed into "castrates"; the 

 spermatogonia and cells of Sertoli, which were present in great 

 quantities, were unable to prevent eunuchoidism. When more 

 interstitial cells were present, the animals showed almost 

 normal genital organs, although in the tubules only cells of 

 Sertoli were to be found. When the interstitial tissue was well 

 developed or hypertrophied, the sexual characters were normal, 

 or even in some respects hypertrophied. 



Steinach concluded from his experiments on rats that in 

 the higher animals the individual differences in the develop- 

 ment of the somatic sexual characters and in the sexual 

 activity are caused by differences in the quantity of inter- 

 stitial cells. This suggestion cannot, I think, be accepted 

 without reserve. 



Kyrle (1911), amongst others, has pointed out that the 

 increase in the interstitial cells is of the nature of a local 

 reaction to the tubules degenerating. 



