TO INTERNAL SECRETION 



period when the antlers have just begun to grow, these remain 

 covered by skin, forming the " peruke " antlers. If castration 

 be carried out after complete development of the antlers, these 

 are shed prematurely, and replaced by imperfect structures. 

 Analogous results are recorded in the fallow deer and prong- 

 buck (Antilocapra americana). As pointed out by Marshall, it 

 is of interest to note that in the eland and in horned cattle, 

 where both sexes possess horns, the growth and development 

 of these structures are not affected by castration. 



Changes in the bodily conformation as a result of castration 

 in quite young animals also occur in sheep, guinea-pigs, oxen, 

 and other animals. In the case of the cock, it is well known 

 that castration arrests the development of the comb and spurs. 



Experiments of a somewhat different nature must now be 

 referred to. Bouin and Ancel tied the vasa deferentia in 

 different animals. The result of this operation was that the 

 seminiferous tubules atrophied, while the interstitial cells were 

 unaffected. These authors were the first to point out the 

 distinctly glandular appearance of these interstitial cells. 

 They suggest that it is owing to the presence of the interstitial 

 tissue that the secondary sexual characters become developed, 

 and that this is due to the activity of a definite internal secre- 

 tion on the part of the interstitial cells. Bouin and Ancel 

 report further that subcutaneous injection of extract of the 

 interstitial tissue in guinea-pigs diminishes the effects of 

 castration, and tends to promote growth. In a still further 

 communication, these authors state that the development of 

 the interstitial glandular-looking tissue coincides with the first 

 occurrence of spermatogenesis. Other authors also lay great 

 stress upon the importance of the interstitial cells of the 

 testis. 



Shattock and Seligmann have also studied the effect of the 

 occlusion of the vasa deferentia in sheep and fowl, and find that 

 this does not hinder the full development of the secondary 

 male characters. Since castration does hinder this develop- 

 ment, it follows that the metabolic results arising from the 

 functions of the testis must be attributed to the elaboration of 

 an internal secretion and its absorption into the general 

 circulation. These authors agree with Bouin and Ancel that 

 the interstitial cells of the stroma have characters so unmis- 

 takably glandular that some secreting function must be 



