356 H. HONDA. 



membrane (Fig. 39) and show a tendency to fuse with each 

 other. There are some cells which have two or more condensed 

 nuclei. These seem to be the products of the fusion of two or 

 more smaller spermatids. Some of the retrogressed cells of the 

 smaller spermatids attach to the epithelium, and on these cells 

 other cells attach themselves ; thus they form layers as shown 

 in Fig. 38. In other cases they are irregularly attached to the 

 epithelium. When they attach themselves to each other they 

 show a polygonal shape. 



A, b and c in Fig. 38 are parts of adjacent cysts, where fully 

 developed spermatozoa occur though not shown in the figure. 

 The cells occurring between the cysts are the retrogressed smaller 

 spermatids produced in the cyst c, and the epithelium proper is 

 very thin as seen between cysts a and b. As we see in the figure 

 these cells are not equal in size. In some of them the nuclei are 

 broken up and their fragments are seen scattered throughout the 

 cells. The others still show condensed spherical nuclei. As 

 stated already the larger spermatids rarely degenerate. These 

 larger spermatids may become like the cells just mentioned. 

 Though degenerating larger spermatids mingle among these cells, 

 there is no criterion by which they may be distinguished from 

 retrogressed cells of the smaller spermatids. 



Some of these cells may be absorbed by the epithelial cells, but 

 how far the absorption proceeds is at present undetermined. 

 When these cells attach to the epithelium the functional sperma- 

 tozoa are already fully developed. Afterwards the wall of the 

 cyst ruptures, and these cells being deprived of their connection 

 with the testis are destined to disappear. It is possible that they 

 are extruded from the testis along with the spermatozoa. I have 

 observed epithelial cells of the cyst and retrogressed cells of the 

 smaller spermatids in some of the vasa deferentia. The sec- 

 tions of the testes of the old males show remarkable changes. 

 Their walls are thickened and neither spermatozoa nor the cysts, 

 which fill the young testes, can be seen. 



IV. NEOTHOMASIA POPULICOLA AND MACROSIPHUM AMBROSIA. 



The testes of embryos of Neothomasia populicola and Ma-cro- 

 siphum ambrosia are in the early stages, but those of larvae are 



