SEASONAL CHANGES IN INTERSTITIAL CELLS 487 



ules which once developed in the peripheral cytoplasm, as will 

 be indicated later, are preserved even in Carnoy's fluid and after 

 such fixation are stained black with iron hematoxyhn. This pig- 

 ment is darkened with osmic acid, but is not stained with ordinary 

 hematoxylin or eosin. The granules are usually aggregated at 

 one side of the nucleus, which is then somewhat eccentric, as 

 may be seen in figure 2. 



In the material fixed in the modified Zenker's fluid and 

 stained with copper hematoxylin, there appear to be a few other 

 granules in the cytoplasm. These vary greatly in size from 

 very small ones about the size of mitochondria to larger ones 

 of the size of the pigment granules. From their staining reac- 

 tion and the fact that they are not always preserved by the 

 above method but show as small vacuoles in the dense cyto- 

 plasm at certain stages, and especially so after Carnoy's fixer, 

 they undoubtedly contain a lipoid moiety. The only thing of 

 a mitochondrial character that could be demonstrated in the 

 interstitial cells at any period were these fine granules which 

 were most clearly shown with copper hematoxylin. However, 

 this point needs further investigation with different and more 

 carefully conducted technique, as a particular tissue may be 

 refractory to a particular technique even in the hands of ex- 

 perienced workers (c.f., e.g., Duesberg, '17). Whitehead ('04, 

 '05, '08) has described granules in the cytoplasm of these cells 

 in the testis of the pig and other animals, which he finally 

 concludes ('12) are a combination of protein and fatty material 

 and somewhat of the nature of mitochondria though differing 

 from the latter in certain staining reactions and in size, generally 

 being larger. He questions the presence of mitochondria as spe- 

 cific granules in the interstitial cells of the testis. Granules, 

 probably of a similar nature, are mentioned by other authors 

 (Regaud, '01, Hanes, '11). The correspondence or identity of 

 these granules with the ones described here in the woodchuck 

 can not be stated at this time, since this would involve special 

 work of a microchemicai nature, which was not anticipated when 

 this work was commenced. 



