354 H - HONDA. 



There must be an interaction, probably chemical, between the 

 sustentacular cells and the larger and smaller spermatids. The 

 larger and smaller spermatids in the outer part opposite the sus- 

 tentacular cells and in the central part of the cyst generally move 

 among the tails of the other spermatids toward the sustentacular 

 cells, but those in the other parts move toward sustentacular cells 

 along the epithelium. 



Developed smaller spermatids (Fig. 31) are seen among the 

 larger spermatids near the sustentacular cells, and do not show 

 any inferiority to the larger spermatids in moving toward the 

 cells. Before the nucleus of the larger spermatid show r s marked 

 differentiation the smaller spermatids have retreated a little 

 towards the interior. In other words, well developed smaller 

 spermatids approach towards the sustentacular cells, but do not 

 attach to them. I have examined many smaller spermatids in 

 order to see whether they develop apical parts. Figure 30 shows 

 a developing smaller spermatid, which has a cone-shaped apical 

 part. There is a developed smaller spermatid, which seems to 

 have a \vell-developed apical part, but we cannot distinctly ob- 

 serve since it is seen in close contact with the tails of the larger 

 spermatids. In most of the smaller spermatids, which have elon- 

 gated tails, I have not, however, observed developed apical parts. 



As to the interpretation of the cells identified as smaller sper- 

 matids, may they not be degenerating larger spermatids? So 

 far as my observation goes the larger spermatids rarely degen- 

 erate ; moreover, it is not hard to distinguish degenerating young 

 larger spermatids from the smaller spermatids, since the former 

 are not only much larger than the latter, but the nucleus of the 

 larger spermatid becomes vesicular while the nucleus of the 

 smaller spermatid is condensed. If the larger spermatids devel- 

 oped to the stage shown in Fig. 19 begin to degenerate, we can 

 recognize them by the difference in the state of the nuclei. If the 

 almost fully developed spermatids begin to degenerate, it is quite 

 easy to tell them from the smaller spermatids, since they have 

 very slender nuclei and the smaller spermatids, which are seen in 

 the same cyst with them, have spherical nuclei. If degeneration 

 of the larger spermatids should occur at the stage in which they 



