INTERSTITIAL CELLS OF TESTICLE IN DIDELPHYS. 1 77 



been observed but is probably amitosis. Perhaps the nuclear 

 depression just mentioned may be considered as an indication 

 of direct division, but it must be stated that the number of 

 cells in which this was noted greatly exceeded the number of 

 binucleated cells. Mitotic division of the interstitial cells in 

 the opossum, although observed occasionally, is rare. Jordan 

 (1911, Fig. 7) has mentioned it. 



The structure of the groundsubstance of the protoplasm varies 

 considerably after the different fixatives. After all reagents that 

 preserve the chondriosomes it appears homogeneous and exhibits 

 a remarkable affinity for a number of dyes. In preparations 

 made after Benda's method it stains intensely with sulfalizarin. 

 Acid fuchsin is retained by it so tenaciously that the seminal 

 epithelium usually has to be almost entirely unstained in order 

 to obtain the proper grade of differentiation in the interstitial 

 cells. Mulon (1911, i and 2) describes in the cells of the cortical 

 suprarenal, in the corpora lutea and in the interstitial cells of 

 the ovary, an amorphous, siderophile or osmiophile substance 

 which, he supposes, is formed by the coalescence of chondrio- 

 somes. This substance he considers as a secretion which accumu- 

 lates in the cell and is finally eliminated in bulk. Athias (1911), 

 however, believes in the presence of a diffuse lipoid formed at the 

 expense of poorly preserved chondriosomes. It is possible that 

 the diffuse substance observed in my material may be the product 

 of secretion, as we shall later see, but it certainly has nothing 

 to do with artificial or natural disaggregation of the chondrio- 

 somes, for these bodies appear well preserved within it. 



Lenhossek (1897) was the first author to describe the centers 

 of the interstitial cell. In man he describes a darker inner zone 

 an "endoplasm" which corresponds obviously to the idiosome, 1 

 although he was not able to demonstrate the presence of centri- 

 oles within it. These have been recently brought into evidence 

 in human material by Winiwarter (1912, i), who found them to 

 be rod-shaped. In the interstitial cells of the cat Lenhossek 

 undoubtedly saw both the idiosome and the centrioles. In the 

 opossum I find that there exists in most of the interstitial cells, 



1 In future I shall adopt the spelling idiosome, as proposed by Regaud (1910), 

 instead of idiozome, for the reasons assigned by that author. 



