260 R. R. HUMPHREY 



The testis of but one specimen of Amblystoma punctatum 

 has been examined. This animal was taken from a pond in 

 late INIarch during the mating season. The lobules had pre- 

 sumably been emptied or partially emptied some time earlier, 

 for regeneration was well under way. Many lobules were almost 

 entirely filled with secondary spermatogonia. - The interstitial 

 cells had reached a late stage of development. They were, 

 indeed, well on their way toward total disappearance around the 

 apices of the lobules, and even where most numerous, near the 

 periphery of the testis, an extremely large number of them had 

 nuclei with the chromatolytic figures indicative of degeneration. 

 They, as well as the degenerating portions of the lobule, contained 

 numerous lipoid droplets. Fuchsinophile granules were also 

 present in large numbers The cells were arranged in sheaths 

 around lobules; these cut in cross-section gave the usual 'epithe- 

 leoid ring' picture. 



Testes of Plethodon glutinosus, Plethodon cinerius erythrono- 

 tus, Spelerpes bilineatus, and Gyrinophilus porphyriticus have 

 also been examined. All of these were taken prior to the forma- 

 tion of spermatozoa. No interstitial cells were present between 

 the lobules of developing spermatogonia ; neither were any present 

 in an extensive shrunken caudal portion of the testis, such as is 

 found in Desmognathus during the summer months. Interstitial 

 cells, if formed in these animals, probably persist but a short 

 time, as in Diemyctylus. Material for a further study of the 

 testes of these forms is now being collected; this will be reported 

 separately at some later date. That interstitial cells were not 

 found in the specimens examined bears out the statement already 

 made: that they show no constant, definite relation to the pro- 

 gressive phases of spermatogenesis, but are absent from regions 

 in which developmental processes are in progress. 



■ DISCUSSION 



Throughout the preceding description the relation of intersti- 

 tial cell development in urodeles to the condition within the 

 lobule has been emphasized. This, briefly stated is: 1) that 

 throughout their period of development, from their early mitoses 



