488 ANDREW T. RASMUSSBN 



A few of the larger cells contain nearer the periphery of the 

 cell other fatty globules which are blackened by osmic acid, 

 and which are very much more soluble, disappearing even more 

 readily than the fat of ordinary adipose cells. These are the fatty 

 granules so often found in these cells in animals generally. 



In addition to the above described interstitial cells, which 

 for convenience will be spoken of hereafter as the ordinary type 

 of interstitial cells, there are scattered here and there, some- 

 times singly and sometimes in small groups, in the inter- 

 stitial tissue and quite frequently adhering to the basement 

 membrane of the tubules, a second type of Leydig cells. These 

 are much fewer in number but larger in size and contain large 

 pigmented granules to such an extent that the nucleus may 

 be crowded into an irregular space between the granules or to 

 one side of the cell. The nucleus is frequently irregular in 

 shape, in conformity to cytoplasmic pressure, and occasionally 

 gives the appearance of being in the process of degeneration. 

 A group of such cells is shown in figure 3 in connection with a 

 few interstitial cells of the ordinary type, which, as described 

 above, also contain pigment but in much smaller quantities 

 and as smaller granules. Occasionally the pigment granules 

 in these large cells, which may be spoken of as pigment cells, 

 are nearly as large as the nucleus (fig. 5). The presence of 

 so many large pigment granules may make the cell outline 

 very irregular, as may be seen in the upper left hand corner 

 of figure 2 where two cells of this kind are shown with the 

 pigment granules stained black thus obscuring the nucleus. 

 These larger pigment granules are evidently of the same com- 

 position as the smaller ones, staining black with copper hema- 

 toxylin and iron hematoxylin, at least on the surface, dark- 

 ened with osmic acid, also mostly on the surface, but not stained 

 with ordinary hematoxylin or eosin. Acid fuchsin may stain 

 some of them red. 



Whitehead ('08 a) in reporting on the cryptorchid testis of a 

 horse, describes cells of a similar character filled with a lipo- 

 chrome which had pushed to one side the nucleus, which was 

 small and pyknotic. He concluded that since there was a 



