No. I.] SPERMATOGENESIS OF BATRACHOSEPS. 47 



sphere on the other. These two classes of fibers are apparently 

 only fed from the cytoplasm proper and to a limited extent also 

 from the granules of the plasmosphere, and this latter probably 

 only during the metaphase of the mitosis. At that time many 

 of the mantle fibers are seen to end in the granules of the 

 plasmosphere (Figs. 48-56). Also during the early anaphase 

 such connection between the mantle fibers and the plasmo- 

 sphere granules may be observed. The polar fibers and mantle 

 fibers sometimes reach the cell wall and connect directly with 

 it, but generally the fibers end in a marginal layer of alveoles, 

 which, however, is never as regular as that figured by Biitschli 

 and his school. These two classes of fibers at the end of 

 mitosis resolve themselves into plasmosphere and cytoplasm 

 proper, while the central-spindle fibers reconstitute themselves 

 into granosphere, or remain for a long time comparatively 

 unchanged as a spindle bridge between two cells. 



There can be no doubt as to the continuity of the central- 

 spindle fibers from one pole to the other. In the later stages 

 of the anaphase when the central spindle is being contracted 

 we can follow without any diiificulty the whole course of 

 one or more fibers from one pole to the other (Figs. 57-62). 

 These continuous fibers are much thicker than the early fibers 

 of the central spindle, and it appears to me as if they origi- 

 nated by the fusion of several of the earlier fibers. At this 

 stage of the central spindle the various fibers constituting the 

 same vary greatly as to thickness as well as to structure. 

 While some are very thick, others again are as thin as they 

 were in the earliest stages of the spindle. Some of the fibers 

 are beaded like the contractile fibers, others are smoother 

 (Fig. 59) and show only the original structure of alternating 

 granules. The origin of the central spindle of the spermato- 

 cyte is less clear. Here the mantle fibers appear first, being 

 reconstructed fiber cones. These mantle fibers meet and form 

 a very wide spindle (Fig. 94) with very deeply sunken poles. 

 At a later stage the central spindle is found inside of this 

 wider mantle spindle, but as regards the process by which it is 

 formed, I have no satisfactory observations upon which to base 

 any theory. 



