24 HARLEY N. GOULD 



fibers begin to grow (fig. 33); in others many nuclear vesicles 

 remain when the axial bundle is much longer than the cell 

 (fig. 36). 



The outgrowth of the axial fibers takes place in a manner 

 similar to that described for other atypical sperm. The centri- 

 oles gather at the periphery of the cell (fig. 32) and become 

 grouped closely together. From each centriole a flagellum grows 

 out of the cell, while at the same time each centriole divides 

 and the migratory daughter elements move away through the 

 cytoplasm, forming between them and the stationary daughter 

 elements, the axial bundle. The migratory daughter centrioles 

 grow straight through the body of the cell, apparently not 

 through its greatest diameter, however; and before they reach 

 a surface again they disappear (figs. 34, 35). The fibers which 

 they have formed continue to grow and protrude from the cell. 

 Before emerging from the cytoplasm the fibers are gathered into 

 n very compact bundle (fig. 36) at their anterior ends. While 

 the axial bundle is elongating the flagella at the posterior end 

 of the cell experience some growth though much less than that 

 of the axial bundle. 



The axial bundle, as it grows out of what may be termed the 

 anterior end of the cell, carries part of the cytoplasm with it; 

 and the longer the bundle becomes, the more of the cell substance 

 is disposed along it (fig. 38) until all the cytoplasm is used up 

 and the spermatozoon reaches its adult form (figs. 39 and 61). 

 When adult it is about one-third the length of the eupyrene 

 sperm (fig. 60). The cross section of the apyrene spenn (fig. 

 39c) shows that the axial fibers are arranged about the periphery 

 of the cytoplasm which has been drawn out from the cell body, 

 and that there is a darkly staining core running through the 

 center. This core begins to be evident at about the stages of 

 figures 36 and 37, or even previous to that time. In the earlier 

 stages it can be seen when looking down on the cell as in the 

 above figures; but when looking at a cross section of the cell as 

 in figure 40a, the axial bundle appears as a flat plate in which the 

 individual fibers are not clearly separated and in which the core 

 is not definitely shown. Sometimes a slight thickening can be 



