MARK AND COPELAND. 



SPERMATOGENESIS OF VESPA MACULATA. 



73 



3) ; unlike the corresponding stage in the honey bee, there seems to be 

 no evidence that these fibres connect with the proximal centrosome ; 

 however, numerous extranuclear fibres extend from the distal centro- 

 some in the direction of the proximal 

 one. 



At this stage the interzonal body 

 already lies near the proximal cen- 

 trosome. 



The proximal end of the cell now 

 elongates (Figure 4), and there is 

 formed a small bud of cytoplasm 

 containing the interzonal body and 

 the proximal centrosome. This bud 

 remains for a time connected with the 

 cell by a neck-like process of cyto- 

 plasm, through which may be traced 

 extranuclear fibres. This connecting 

 process of cytoplasm becomes more 

 and more attenuated until a complete 

 detachment of the protoplasmic glob- 

 ule is effected. 



This " Richtungskorper " consists 

 chiefly of the interzonal body, but in 

 most cases the interzonal body is 

 surrounded by more of the unmodi- 

 fied cell protoplasm than exists in 

 the corresponding globule of the honey 

 bee. Like the latter, it contains no 

 chromatin. 



We have good evidence to show 

 that the proximal centrosome divides, 

 and that the two daughter centro- 

 somes, in some cases, at least, move 

 apart around the periphery of the 

 globule. This migration may begin 

 before the protoplasmic bud has be- 

 come completely separated from the 

 parent cell. 



During the period of the abstriction of the interzonal body and 

 accompanying cytoplasm, which closely resembles that of the honey 

 bee, the development of the spindle figure is arrested, as in the bee, 

 not being carried- beyond the beginning of the metaphase. It is difii- 



Fi CURES 5-8. Spermatocytes af- 

 ter the abstriction of tlie interzonal 

 body (i.e. .secondary spermatocytes) 

 X 2800. 



FiGURK 5. Spindle figure of sec- 

 ond maturation division in tiic 

 beginning of the metaphase. 



FiGDRE 6. Anaphase of second 

 maturation division. 



Figure 7. Early telophase. 



Figure 8. Late telophase. Sper- 

 matocyte nearly divided into two 

 spermatids. 



