132 Uxpei'imental Orchectomy in Birds 



one of these testes so regenerated under a low magnification, S" obj. 

 PL IV, fig. 3 shows a portion of the same section under a higher magni- 

 fication, \" obj. In some sections the regenerated tubuli seminiferi are 

 seen to be filled with spermatozoa as in the normal gland. 



(20 c.) 



(22 c.) 



Fig. 1. Eegeneration of the Testes after Subcapsular 

 Castration in Fowls. (From Photo.) 



Thus it is clear that a real regeneration of .sperm-bearing testicular 

 tissue occurs after subcapsular orchectomy and this regeneration must 

 take place either from the capsule, or more probably from microscopic 

 fragments of secreting ti.ssue which are left adhering to the capsule at 

 the time of the operation. 



Such evidence as exists goes to show that regeneration of testicular 

 substance within the capsule after removal does not occur, at any rate 

 to any appreciable extent in the case of some mammals. This is a 

 matter of some importance. The domestic fowl has undergone a 

 process of artificial selection in regard to the egg-laying capacity of 

 the female sex gland, and probably also in regard to the sjjerm-forming 

 capacity of the male sex gland, hence it is of interest to find that the 

 testis of the domestic fowl has great powers of structural and functional 

 regeneration after partial removal, greater apparently than exists in 

 mammals. 



