1920] SHARP— SPERMATOGENESIS 261 



4 



(fig. 10, upper cell) and divides by a process of simple fission into 

 two portions (fig. 10, lower cell). These two portions, or blepharo- 

 plast granules as they may be termed, often lie 



very 



in 



complete. As a rule one of the gran- 



ules at once begins to elongate, while the other remains relatively 

 unchanged, so that many cells show two bodies, one of them 

 round and the other comma-shaped, lying close together near the 

 cell membrane (fig. it). At about this stage the granules usually 

 move closer to the nucleus. The comma-shaped granule con- 



tinues 1 

 granule 



The 



granules continue to multiply by fission (fig. 13) until several are 

 present in a row (figs. 14, 15); seven was the largest number 

 counted with certainty. The granules now appear less distinct 

 from one another; it seems that they gradually undergo a coales- 

 cence (figs. 14-16), but it may also be that some of the fissions are 



incomplete, some of the granules therefore never being entirely 

 separate. 



The nucleus at this time moves more closely against the beaded 

 blepharoplast (fig. 15) and begins to draw out into a point by the 

 side of the latter (fig. 16). Both nucleus and blepharoplast con- 

 tinue to elongate spirally, the association between them becoming 

 constantly more intimate (fig. 17). Fig. 18 represents a cell like 

 that of fig. 17 viewed from the direction indicated by the arrow; 

 it is here seen that the blepharoplast is applied along one edge 

 of the flattened point of the nucleus. As the transformation 

 continues the boundary between nucleus and blepharoplast 

 gradually becomes indistinguishable (fig. 19). Even at this late 

 stage the irregular outline of the blepharoplast is still evident; 

 the blepharoplast granules have not yet become so completely 

 coalesced that the thread which they form is smooth in outline. 

 The nucleus continues to elongate and condense, becoming 

 increasingly slender, while two cilia grow out from the blepharo- 

 plast, which projects beyond the nucleus at the anterior end. 

 The spermatozoid is now mature (fig. 26) and ready to escape 

 from the antheridium. 



