GAMETOGENESIS AND SPOROGENESIS 



219 



The nebenkern halves now come to lie on either side of the axial 

 filament and rapidly elongate to form the two "filament sheaths" which 

 become twisted about the axial filament. Their anterior ends appear to 

 attach themselves to the centrioles at the base of the nucleus. As they 

 become longer and thinner they show a series of swellings which may 

 possibly represent accumulations of the central substance. These even- 

 tually disappear and the uniform sheaths extend nearly, if not quite, to 

 the tip of the axial filament. 



ff 



J 



B 



M^^ I 



G - H ^-^ I 



Fig. 133. — Behavior of Golgi material in spermatids of certain insects. A, F, Brochymena; 

 B-E, Euschistus; G-J, Murgantia. Cf. Fig. 130. {After Bowen, 1920, 1922c.) 



Golgi Material (Fig. 133). — In the Hemiptera the Golgi constituents 



of the spermatid usually behave as follows. At the close of the meiotic 



divisions the dictyosomes fuse to form several larger Golgi bodies much 



like those of the spermatocyte. The fusion continues until there is 



formed a single large acroblast,'^'^ which lies near the base of the nucleus 



on the side opposite that to which the centrioles migrate. Ordinarily it 



has a heavily staining shell except on the side next to the nucleus. The 



acroblast soon begins a migration around to the other side of the nucleus, 



passing first to the anterior end of the cell where it pauses for a time. It 



^- Often referred to in the literature as the "spermatid idiosome," or "sphere." In 

 moUusks this mass has frequently been called the "nebenkern." 



