196 



E. UHLENHUTH 



that the presence of a functioning gonad, no matter where it has been 

 grafted, prevents all the consequences of castration and results in normal 

 development of the secondary sex characters, as shown by Marshall and 

 Jolly, by Steinach, and by Moore in rats and guinea pigs, by Goodale, and 

 by Pezard in birds (Fig. 3), by Nussbaum (1909), and Meisenheimer in 



Fig. 3. Shows the effect of castration in the male domestic fowl. Five successive 

 stages of the atrophy of the fleshy appendages of the head following castration. 

 (After Pezard.) 



frogs. The experiments by Nussbaum deserve special mention since this 

 author prevented the implanted testes from forming any nervous connec- 

 tions. Probably the feeding or injection of sex glands has the same effect 

 as transplantation (Pezard, though denied by Meisenheimer and Walker). 

 Important evidence in favor of the hormonic action of the sex glands was 

 furnished by Lillie, who discovered that in twins of different sex the sex 

 characters of the female are more or less changed into male characters if 

 the male hormones are permitted to reach the female through the circula- 

 tion of the blood. 



Not the entire sex gland but only the interstitial cells of the testicle 



