BAUMGARTNER : SPERMATID TRANSFORMATIONS. 53 



('00) found it in Pygssra. The central ball sometimes shows 

 vacuoles (fig. 16), but most frequently stains as one mass. In 

 some cysts with cells resembling fig. 16, it is difficult to dis- 

 tinguish between nucleus and nebenkern, yet the latter's stain 

 is never as intense as that of chromatin. The stages shown in 

 figs. 13 and 14 persist for a long time, and it is probable that 

 this is the end of the telophase and the beginning of the sperma- 

 tid transformations. 1 have treated the above more in detail 

 and shown more drawings than its importance may deserve, 

 but it is in these stages that Gryllus seems to differ from other 

 species, and I have tried to describe and illustrate the apper- 

 ances and changes fully. 



As the cell elongates, the axial filament grows out, the neben- 

 kern approaches it, and a junction is effected in such a way 

 that the axial filament runs over the surface of the nebenkern. 

 (Figs. 18, 27, 28, and 30.) At first the nebenkern is still al- 

 most round, but it begins to elongate and the dark inner ball 

 sends out a protrusion to the nucleus, and sometimes back to 

 the point of separation between the external envelope and the 

 axial filament. The outside ring disappears and the dark mass 

 moves down the axial filament. (Fig. 31.) In many cases it 

 breaks up into several small drops, which appear at intervals on 

 the axial filaments. ( Figs. 34 and 36.) In fig. 38 is seen such a 

 hanging drop. In this way the nebenkern material is distrib- 

 uted over the axial filament and forms a sheath around it. 



2. — The Acrosome. 



The second extra-nuclear body I shall call the acrosome, as it 

 forms the point of the spermatozoon head. I could not trace its 

 origin, because the fixation was not definite in some of the early 

 stages. Fig. 4 shows a small, darkly staining body, which 

 may be a centrosome, but more likely is the beginning of the 

 acrosome, of which figs. 7, 9 and 10 show developing stages, 

 and figs. 11, 13 and 15 more advanced ones. Sometimes the 

 central portion stains darkest (figs. 11, 32, and 36), but more 

 frequently there is a small clearer space in the center sur- 

 rounded by a ring or band of darker material. ( Figs. 10, 13, 27, 

 and 30.) This ring usually stains darker on one side, very 

 often on the side toward the nucleus. 



The position, which is, with few exceptions, in the angle be- 

 tween the nucleus and the nebenkern, induces me to consider 



