ON THE SPERMATOGENESIS OF THE SILK-WORM. I2g 



It is certain that these round cells in the testicular follicle 

 are genital cells. When the larva is about to be hatched, three 

 depressions appear on the follicular wall. These gradually 

 deepen until four cavities are formed. This is shown in 

 fig. 5 /. Hand in hand with this change another depression 

 appears on each of these testicular tubes as fig. 5 i shows, and 

 in a testis of a larva four days old, there is seen a large cell 

 in each of these secondary depressions of the follicle. This 

 large cell is the origin of Verson's cell found in the blind end 

 of the testicular follicle. Similar structure is also found in a 

 testis a little younger than this, but here a distinct membrane 

 exists between the depression and the follicular space (fig. 6), 

 so that the depression is produced by the swelling in of one of 

 the cells of the follicular wall, and has no connection with 

 the genital cells lying in the follicular space. It is therefore 

 certain that Verson's cell is derived from one of the follicular 

 cells, and not from the genital cells. 



This depressed cell gradually loses its membrane and pro- 

 duces amoeboid processes between the genital cells (fig. 11). It 

 always has an elliptical nucleus which contains many chromatin 

 granules (figs. 9, 10, 11, 12, 13, v), staining very deeply by such 

 reagents as hsematoxylin, carmine, and aniline dyes, and is 

 connected with the follicular wall by a protoplasmic strand 

 (fig. 8, p). It thus resembles very much the nucleus of follicular 

 cells (fig. 6) which also contains many chromatin granules. 

 Contrary to the assumption of Verson it has no nucleolus, nor 

 any karyokinetic division to be found in it at any stage of its 

 existence from the early beginning till the death of the moth. 

 Verson's cell is, as stated above, generally situated in the blind 

 end of the testicular follicle, around which the youngest sexual 

 cells are found (fig 7 v). Sometimes, however, it happens to be 

 placed at one side of the follicle (fig. 10 v) where more developed 

 genital cells are found, the most interesting thing about here is 

 that the youngest genital cells are here also found at the blind 

 end and not around Verson's cell. As will be seen in fig. 10 the 

 genital cells at the blind end of the follicle divide profusely as 

 usual, although Verson's cell is not present, and this shows that 

 Verson's cell has nothing to do with the formation of genital cells. 



The division of Verson's cell takes place, as Verson states, 



