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several months that the spermatozoa remain in the testis num- 

 erous lipoid droplets may appear between lobules, though the 

 cells do not then, as a rule, round out to a polyhedral form be- 

 cause of the continued pressure of the distended lobules. The 

 appearance of typical interstitial cells, as in other urodeles, 

 occurs only when the lobules have been emptied and degeneration 



Fig. 7 Longitudinal section of the testis of Diemyctylus after the spring 

 mating season. Only a few of the lobules still contain spermatozoa. The re- 

 cently emptied lobules are surrounded by interstitial cells, whose lipoids have 

 been blackened by the osmic acid of the fixing fluid (Bensley's). c, central col- 

 lecting duct; b, branch of central collecting duct; s, lobules filled with second- 

 ary spermatogonia; sp., lobules filled with spermatozoa; i, interstitial cells; fi, 

 boundary plane. X 16. 



has begun. As this happens in the case of the more caudal ones 

 during the fall mating, there are present during early winter 

 numerous lobules surrounded by well-developed interstitial cell 

 sheaths. The lobule appears to degenerate rapidly; sometimes 

 cords and masses of interstitial cells appear within which but 

 little trace of the lobule remains, although in other cases its 

 connective-tissue wall, thickened, convoluted, and hyaline, 



