68 R. H. WHITEHEAD 



but the interstitial cells contained no red-staining material. 

 Thinking that the failure to stain might be due to the small size 

 of the granules, recourse was had to the strong solution recom- 

 mended by Herxheimer for scharlach (absolute alcohol 70 cc, 

 10 per cent solution of caustic soda 20 cc, distilled water 10 cc, 

 Sudan to saturation) with the result that sections stained ten or 

 fifteen minutes at room temperature offered a very satisfactory 

 demonstration of the granules in red. Some of the cells presented 

 a quite exact reproduction in red of the picture of the granules as 

 seen in paraffin sections stained by the other methods. They 

 were situated in small vacuoles between the trabeculae of the 

 spongioplasm, and were most numerous at the periphery of the 

 cells (fig. 5). It is to be noted, however, that many of the gran- 

 ules appeared smaller than in the other preparations; and in 

 many of the cells this small size of the red granules was quite pro- 

 nounced, as if only a localized portion of their substance had been 

 stained by the Sudan (fig. 6). Thus there was obtained direct 

 proof that the granules contained fatty material in addition to 

 the proteid constituent demonstrated by the other methods. 



It remained to detennine whether or not these granules should 

 be classed with the lipochromes, as fatty pigment has been found 

 in the interstitial cells of several mammals. According to Sehrt,^ 

 who has made an extensive study of this pigment in the human 

 testis, it is stained by Sudan even in sections of material that has 

 been imbedded in paraffin. In the case of the pig and the cat 

 the granules were colorless in frozen sections, and it was not pos- 

 sible to stain them with Sudan in paraffin sections of formalin 

 material. It seems certain, therefore, that the granules are not 

 lipochrome. 



From this study I conclude that the granules in the interstitial 

 cells of the pig, and probably also of the cat, consist of a combina- 

 tion, either physical or loosely chemical, of proteid with fatty 

 material. It also shows that the pig's interstitial cells, which 

 contain no individual globules of lipoids, are no exception to the 



' Sehrt. Zur Kenntniss der fetthaltigen Pigmente. Virchow's Arch., Bd. 

 177, 1904. 



