no 



INTERNAL SECRETIONS 



A. MAMMALS. 



I. The Interstitial Cells of the Testicle. 



In his first account of the interstitial cells, Ley dig (1850, 

 p. 47) described them as follows: — "One sees in studying the 



^l.'^ 

 i 



m 







m 



1^4/^®' 





IP'" 



t^' ; 



&-.\.r***v^ 



■iC* 





.'^f 



v% 





..'*5' 



t: 









.. >• ^'. 



Fig. 51A, — Section tJiroii^Ji tcbtich "/ nnnnn/ guinea pig, aged 

 about 4|- months. (Prot. Nr. 27). x 280. Quadrangle 

 between four tubules. Interstitial cells surrounding a 

 capillary. Granulated interstitial mass. 



comparative histology of the testicle that besides the semin- 

 iferous tubules,, blood vessels and nerves, there is present 

 in the testicle of mammals another constant part, a cellular 

 mass which surrounds the blood vessels when present only in 

 small quantity, and in which the seminiferous tubules are 



