SEASONAL CHANGES IN INTERSTITIAL CELLS 505 



111 fact, claims to have demonstrated such a passage of cells 

 into the tubules. Hanes ('11), on the other hand, repeated 

 (ioldmann's vital staining method and could find no suggestion 

 of this migration of cells as described by Goldmann. 



SUMMARY 



1. In the woodchuck (Marmota monax) during late summer 

 and autumn, the interstitial cells of the testis are minimal 

 in size and probably reduced in number. The scanty cytoplasm 

 of these cells contains numerous pigment granules, some fine 

 lipoid granules, but only a very few of the cells contain the 

 coarser and more fat-like globules which are easily demon- 

 strable with osmic acid. There are a number of large inter- 

 stitial cells, which are gorged with prominent pigmented gran- 

 ules and which have resulted from a degeneration of some of 

 the other common and more numerous type of interstitial cells. 

 A new spermatogenic cycle is in progress. The testis is small, 

 dark in color and abdominal in position. 



2. There is no sudden change in the interstitial cells with 

 the onset of hibernation and little or no change during dor- 

 mancy, except that there is a slight gradual decrease in pig- 

 mentation. Spermatogenesis remains much the same during the 

 torpid state as just before winter-sleep sets in. The tubules 

 are filled with spermatocytes showing open maturation figures 

 during the entire winter. 



3. In the spring as the animal is waking up from hiber- 

 nation, the interstitial cells rapidly enlarge and apparently 

 increase in number. The nucleus increases only slightly. The 

 great increase is primarily in the cytoplasm and is due to the 

 development of a dense central mass of cytoplasm and the 

 accumulation of fatty globules in the more peripheral portion. 

 Fine lipoid granules are also abundant in the central cytoplasm. 

 Ths great interstitial cell development forces apart the tubules 

 and doubles the diameter of the testis, which descends into 

 pouches essentially representing a scrotum remaining in com- 

 munication with the abdominal cavity proper. Spermatogenesis 

 suddenly shows renewed activity and free sperms are seen by the 



