II 



MEIOSIS 



65 



(4) Does any Stage comparable to the Germinal Vesicle occur in 



Spermatogenesis ? 



The undoubted correlation between the pecuhar conditions of the 

 germinal vesicle and the long duration of the growth period in the female 

 meiotic phase, and probably also with the deposition of yolk, makes it 



/^"^^ 



,^0/ \ 



V X 











«i5' 



x". 



<> 



r, > 



VD 



H 





7i:. 



A^ 





M 



K 



♦ ♦'■ 



N 



i? 



Fig. 28. 



Germinal vesicle-like stages in spermatogenesis. A-G, Notodrotnas monacha (after Schiualz, A.Z., 1912); 

 H-N, Scolopendra hews (after Blackman, B.M.C.Z.H., 190.5). In both cases the principal stapes between the 

 pachytene nuclei (A and H) and the formation of the definitive bivalents (G and N) arc shown. 



a priori improbable that a fully developed germinal vesicle stage should 

 be a normal occurrence in spermatogenesis, where the duration of the 

 growth period is comparatively short, and there is little or no deposition 

 of reserve food material. 



Nevertheless, stages obviously corresponding with the germinal 

 vesicle occur in the male meiotic phases of some animals. There is often 



