54 KANSAS UNIVERSITY SCIENCE BULLETIN. 



the differently staining bodies as the same organ of the cell. 

 For some time after the nebenkern has disappeared the acro- 

 some keeps its position ; then it approaches the nuclear wall, 

 flattens against it, and later wanders to the apical end, where 

 it forms the tip of the spermatozoon. (See figs. 32-36 and 

 39-42.) Fig. 16 shows the acrosome back of the nebenkern. 

 It is not an isolated example, still, I think, it is an abnormality. 

 Fig. 37 shows an apparent division of the acrosome. I did not 

 see enough instances to consider it a regular occurrence. 



3. — The Axial Filament. 



As the cell is elongating, the axial filament is seen apparently 

 growing out of the nucleus. I do not mean to say that it grows 

 out of the nuclear substance, but in almost every cell observed, 

 where the axial filament was incomplete, there was rather a 

 large mass of chromatin gathered at the place where the axial 

 filament was attached to the nucleus. It may be that the 

 smaller one of the extra-nuclear bodies in figs. 4, 7 and 9 is 

 a centrosome which is passing to the equatorial region of the 

 nucleus, where it later develops the axial filament. As already 

 noted, the axial filament does not pass through the nebenkern, 

 but only over its surface. Fig. 29, a, b, and c, shows different 

 cross-sections through the elongating cell. In b the axial fila- 

 ment was cut at an angle. 



4. — The Centrosome. 



I have not followed the centrosome through its migrations. 

 In fig. 2 one of the two bodies is the centrosome, but I did not 

 trace its changes farther. 



5.— Cell Body. 



The cells, up to the stage of figs. 13 or 14, have been scat- 

 tered promiscously through the cyst ; but as the cell begins to 

 elongate, the one end becomes the anterior- nuclear end, and 

 it shifts to the periphery of the cyst. The central part of the 

 cyst now shows the so-called central lumen. As the lengthen- 

 ing goes on the heads of the forming spermatozoa are all turned 

 toward the distal end of the cyst. The cyst becomes very nar- 

 row and long, apparently preparing to contain the long, slen- 

 der spermatozoa. Near the rachis the spermatozoa seem much 

 twisted, and I surmise that they turn so as to have the head 



