RELATING TO SECONDARY SEXUAL CHARACTERS. 35 



in a race of Leghorns, the males of one of which become cock-feath- 

 ered before the other. May not this difference depend on the length 

 of time endocrine cells remain or begin to develop? A histological study 

 of the two types would be of the greatest interest. 



ENDOCRINE CELLS IN THE TESTES OF MAMMALS. 



In man and other mammals it has long been recognized that in 

 addition to the germinal cells of the testis there are also present other 

 cells, sometimes called interstitial cells, that, so far as known, have no 

 immediate function in connection with the germ-cells, or at least that 

 have other important functions outside the relation to the reproductive 

 organ. That some internal secretion from these cells has an important 

 influence on the secondary sexual characters rather than anything done 

 by or produced by the germinal cells has been very clearly shown by 

 evidence derived from three separate sources, namely, from the 

 operation known as vasectomy, from an exceptional condition known 

 as cryptorchidism, and more indirectly from X-ray treatment. Vasec- 

 tomy involves either cutting the vasa deferentia in such a way that 

 the cut ends do not reunite. In consequence of the closure of the 

 outlet of the testis the germinal cells slowly degenerate, and finally 

 completely disappear. How such an effect is produced we do not know. 

 That this result does take place is borne out by the unanimous testi- 

 mony of all those who have successfully performed the operation. 

 Ancel and Bouin showed (1903) that breaking the continuity of the 

 vas deferens suppressed spermatogenesis in 8 to 12 months. Both 

 the Sertoli cells (the nourishing cells of the germinal epithelium) and 

 the interstitial cells persist. Such animals remain sexually active and 

 their secondary sexual characters are not affected. Marshall states 

 that in the hedgehog the remarkable periodic enlargement of the 

 testis takes place even after vasectomy, although the germ-cells have 

 disappeared. 



In mammals the testes fail at times to pass through the inguinal 

 canal, and, in consequence of their retention in the body-cavity, the 

 germ-cells fail to develop. On the other hand, the interstitial cells 

 of the testis develop normally. Cryptorchid individuals show the 

 normal secondary sexual characters of their species. How retention 

 of the sperm should give rise to the same result as cutting the duct, 

 viz, absorption of the germinal cells, is not known. A possible solution 

 may be found in the pressure exerted on the testes, both when retained 

 in the abdomen and when their outlets are stopped by tying or cutting 

 the ducts. 



Finally, it has been long known that continued or repeated exposure 

 to X-rays or to radium causes the destruction of the germ-cells, but 

 leaves the interstitial cells intact and presumably functional. Destruc- 



