DEGENERATIONS, DESMOGNATHUS 



239 



With the horizontal axis representing the 'spermatogenetic wave 

 and the vertical axis the successive transformations with ad- 

 vancing season, oblique lines upward and to the right would give 

 the similar stages at different seasons. The 'boundary plane,' 

 when it appears, breaks the continuity of such lines. Allowing 

 for the equalization of all stages in duration and extent which 

 such a schema necessitates, it nevertheless gives a good diagram- 

 matic representation of the process of spermatogenesis in the 

 testis of Desmognathus as is indicated by comparing figures 1, 2, 

 6 and 3, from the months of May, June, August and September. 

 To these might be added many others from the yearly cycle. It 

 will be seen the synizeses (E) in front of the 'boundary plane' 

 is in line with the degenerations (D) behind the plane. 



Spermatogenetic wave 

 3 4 5 6 7 



8 



9 



10 



n 



1 



f 



f 



a 



a 



a 



a — primary spermatogonia 

 c — secondary spermatogonia 

 E — synizeses 



g — secondary spermatocytes 

 i — transforming spermatids 

 k — nearly mature spermatozoa 

 m — spent lobules (degenerating) 



b — secondary spermatogonia 



D ■ — degenerations 



f — primary spermatocytes 



h • — spermatids 



j — maturing spermatozoa 



1 — mature spermatozoa 



n — degenerated lobules 



* — boundary plane 



