SPERMATOGENESIS OF CANCER MAGISTER. 29 1 



transformations of Menippe mercenaria, is the same structure 

 which I have called the second vacuole in Cancer magister. My 

 preparations, however, show no such stages which Binford de- 

 scribes and pictures (Figs. 52-60 of Binford, '13), for the develop- 

 ment of this structure. 



During this time the centrosome and the karyosome-like body 

 of the nucleus unite (Figs. 54-56), and elongate into a rod-like 

 structure (Figs. 57 and 58), the so-called central body (Figs. 56 

 and 57, &). At first the central body looks like a dumb-bell 

 (Figs. 56 and 57, b), but as it lengthens out, it loses this appear- 

 ance, becomes more rod-like (Figs. 58-60), and at the same time 

 penetrates the inner or proximal portion of the second vacuole. 

 While all these changes are going on the primary and secondary 

 vacuoles are gradually transforming into primary and secondary 

 vesicles (see Figs. 54-60, v and z/), and from now on they will be 

 designated by the latter names. 



At about the stage represented by Fig. 59, an opening makes 

 its appearance in the middle of the outer, or distal end of the 

 second vesicle. Simultaneously with this, the central body 

 elongates still more (Fig. 59) and its outer extremity seems to 

 hollow out into a thin tube (Figs. 60-62) which soon connects up 

 with the distal opening in the secondary vesicle. As the outer 

 end of the central body hollows out, a ring of densely staining 

 material makes its appearance around the outer opening of the 

 second vesicle (Figs. 61-63, d). In Heidenhain's haematoxylin 

 this ring stains intensely black like the centrosome or the chro- 

 matin. This ring may be spoken of as a chromatin-ring and it 

 becomes more distinct as the distal end of the central body 

 hollows out (Figs. 61-64, d}. Going hand in hand with these 

 modifications are those which take place in the mitochondria- 

 like ring and the nucleus. These two elements fuse into a single 

 structure, a sort of nuclear-mitochondrial cup (Fig. 62, Ji), which 

 stains quite homogeneously, although some part of the mitochon- 

 drial mass seems to persist around the wall of the first vesicle and 

 stains more intensely than the rest of the cup. (see Fig. 62, //). 



As the transformations continue, the second vesicle fits more 

 compactly into the first vesicle (Figs. 63 and 64). The outer 

 portion of the central body has completely changed into a thin- 



