1 64 R. R. HUMPHREY. 



tion of the current spermatogenetic cycle and postpone the 

 beginning of the cycle following. At any rate, no maturation 

 divisions occurred in the fall of 1923 in this species. The sperm- 

 atocytes present in the testis were either delayed in their early 

 development, or their maturation divisions were later prevented 

 by lowered October temperature. Both factors might conceiv- 

 ably be involved in effecting the end result, the elimination of 

 the usual autumnal maturation. Since only spermatids undergo 

 degeneration during winter in Plethodon gkitinosHS, no appendage 

 appeared in the following season. 



Of the other Urodele species developing an appendage, Pletho- 

 don cinerius shows an effect comparable to that in Plethodon 

 glutinosus. In Eurycea the appendage was found during 1924 

 much as in preceding years. No Gyrinophilus males were 

 examined. 



The complete absence of the appendage here reported strik- 

 ingly supports the writer's statement that it is a structure due 

 to environmental effects upon spermatogenetic processes, and as 

 such, may vary from year to year even in the same male. 



LITERATURE CITED. 

 Driiner, L. 



'94 Beitrage zur Kenntnis der Kern- und Zcllcn-degeneration und ihre Ursache. 



Jenaische Zeitschr. f. Naturw., Bd. 28. 

 Flemming, W. 



'87 Xeue Beitriige zur Kenntnis der Zelle. Arch. f. mikr. Anat. Th. I. Bd. 29 

 Hermann, L. 



'88 Ueber regressive Metamorphosen des Zellkerns. Anat. Anz., Bd. 3. 

 Hoffmann, C. K. 



"73-78 Dr. H. G. Bronn's Klassen und Ordnungen des Thierreiches. 6 Bd., 2 



Heft. 

 Humphrey, R. R. 



'21 The Interstitial Cells of the Urodele Testis. Am. Jour. Anat., Vol. 29. 

 Humphrey, R. R. 



'22 The Multiple Testis in Urodeles. BIOL. BULL., Vol. 43. 

 Kingsbury, B. F. 



'02 The Spermatogcnesis of Dcsmognalhus fusca. Am. Jour. Anat., Vol. i. 

 Kingsbury, B. F., and Hirsh, Pauline E. 



'12 The Degenerations in the Secondary Spermatogonia of Dcsmognathus fusca. 

 Jour. Morph., Vol. 23. 



Moore, C. R. 



'24 The Behavior of the Germinal Epithelium in Testis Grafts and in Experi- 

 mental Cryptorchid Testcs. Science, N. S., Vol. 59, P. 41. 



