Fig. 4. Section through a guinea pig's testicle grafted (8 months before fixation) 

 into the castrated male guinea pig and preventing the effects of castration. Demon- 

 strates the endocrin function of the interstitial gland of the testicle. The generative 

 part (seminal tubes) atrophied, the interstitial cells present and hypertrophied. After 

 Steinach. 



Fig. 5. Section through guinea pig's ovary treated with X-rays. Demonstrates 

 the endocrin function of the interstitial gland of the ovary. The generative part 

 (Graaffian follicles) atrophied, the interstitial cells (lutein cells) present and hyper- 

 trophied. After Steinach. 



197 



