igul SHARP— SPERMATOGENESIS IN MARSILIA 423 



from 



granules such as are seen at the poles of the previous mitosis (fig. 15) 

 is a question which must remain in doubt. The cell shown in 

 fig. 18 seems to favor the latter interpretation; at the upper pole 

 there appears to be a small group of granules, while at the lower 



) centrosome 

 centrosomes 



At very late anaphase 

 line radiations form a 



striking system extending through the greater part of the cell 



(fig. 19). 



become short and faint. The 



centrosomes are still growing, and in some cases may already show 

 indications of division (fig. 20, upper centrosome). 



Third spermatogenous mitosis. — There are now 4 cells in each 

 spermatogenous group, and conspicuous in the cytoplasm of each 

 cell (fig. 21) is the centrosome formed during the anaphase of the 

 preceding mitosis. This centrosome undergoes division at once 

 (figs. 22, 23), in fact this process is often seen beginning during 

 the previous telophase (fig. 20). 'The two daughter centrosomes 

 rarely diverge from one another. In two or three cells they had 



mo\ 



and in one uncertain case they appeared to have reached approxi- 

 mately polar positions. As a rule, however, they degenerate in the 

 cytoplasm without performing any further function. At late pro- 

 phase and metaphase they can often be made out in the cell 

 (fig. 24), but they bear no relation to the spindle poles, which are 

 at first rather indefinite, as in the first and second mitoses. The 

 persistence of faint radiations about them helps to make their 

 identification sure. During anaphase they usually lie in the cyto- 



asm 



shown 



26 contains two pairs of minute granules with very faint rays; since 



observed, it is impos 



may mean, but 



moved 



divided again. This renders more certain the interpretation placed 

 upon the paired bodies in figs. 24 and 25. They are doubtless to 

 be identified with the " blepharoplastoid " of Shaw, and are in 

 reality the non-functioning centrosomes. 



