SPERMATOGENESIS OF THE BLACK-CLAWED CRAB. 283 



the spindle fibres (Fig. 22) while at other times it is located out- 

 side the spindle proper, as shown in Fig. 23. As already men- 

 tioned, when the slides were greatly destained, the chromatoid 

 body could be easily distinguished from the chromosomes as it 

 took on a lighter color. The most consistent counts of polar 

 views of metaphase stages showed 62 bivalent chromosomes 

 distributed throughout the plane of the equator (Fig. 24). 



The anaphase and telophase stages (Figs. 25-28) follow quickly, 

 ultimately producing the secondary spermatocytes. Figure 28 

 shows the two types of secondary spermatocytes formed, one 

 containing the single chromatoid body, while the other is devoid 

 of any such structure. These two kinds of secondary sperma- 

 tocytes occur in equal number. 



C. Secondary Spermatocyte Stages. 



The secondary spermatocyte divisions are equational. No rest 

 period is found after the mitosis of the primary spermatocyte, 

 the cells immediately enter the metaphase to undergo rapid 

 division. No good counts of the chromosomes of secondary 

 spermatocytes could be made. The cells on the whole are 

 almost half the size of the primary spermatocytes. 



Figures 29-34 show the typical stages in the division of the 

 secondary spermatocyte which possesses a chromatoid body, 

 while Figs. 35-38 show the same process in the secondary sperma- 

 tocyte that is minus the chromatoid body. The ultimate result 

 of all these divisions is the formation of two kinds of spermatids, 

 one which contains a chromatoid body (Fig. 39) and the other 

 that lacks it (Fig. 44). This latter spermatid is about three 

 times as numerous as the former one. 



D. Transformations of Spermatids. 



The two types of resting spermatids (Figs. 39 and 44) are 

 spherical cells which have large masses of chromatin within the 

 nuclei that stain intensely black with Heidenhain's hsematoxylin. 

 The cytoplasm is uniformly granular, possessing a distinct centro- 

 some. The chromatoid body can be clearly seen within one of 

 the kinds of spermatids (Fig. 39). 



Transformations of the two spermatids occur in similar fashion. 



