130 ON THE SPERMATOGENESIS OF THE SILK-WORM. 



amitotically. Its nucleus becomes constricted into two or more 

 portions producing from one to many small nuclei on the side of 

 the large one. This mode of division is not to be seen in the 

 first larval stages, but commencing generally at the end of it, 

 gradually increasing to the imaginal stage (Figs. 6, n, g, 12, 13 v); 

 but the genital elements are seen to increase in number from the 

 first larval stages, where no division of Verson's cell is found. 



In a testis of an imago after copulation, I have also met with 

 Verson's cell, but now it does not stain so well by the reagents 

 above described as in earlier stages (fig. 13). At this stage, there 

 is seen a number of cells close to Verson's cell, probably corres- 

 ponding with the cells formed by the above described amitotic 

 division of it. These cells also take no stains and contain large 

 vacuoles, showing thus the process of degeneration. (I) 



From all this we arrive at the conclusion that Verson's cell 

 is not a genital cell as Verson states, but it is a supporting cell 

 connecting all the younger genital elements with the wall of the 

 testicular follicle and probably nourishing them. This confirms 

 the assumption of Ziegler and vom Rath (46), who says that " es 

 erscheint eine Deutung zulassig, welche die Befunde von Verson 

 mit denen von vom Rath in Uebereinstimmung bringen konnte, 

 namlich die Auffassung, dass die kleinen Zellen nicht die Ab- 

 kommlinge, sondern sozusagen die Geschwister der grossen Zelle 

 (Verson's cell) sind und dass sie durch successive mitotische 

 Theilung die zahlreichen Samenbildungszellen erzeugen, wahr- 

 end der Kern der grossen Zelle, welche den Character einer 

 Rand- oder Stiitz-zelle hat, mehrfach sich amitotisch theilt." 



Verson's cell may therefore be safely assumed to be a 

 supporting cell of the testicular follicle, and is also to be seen 

 in the blind end of an egg tube as is shown in fig. 14 and in quite 

 young stages, it is very difficult to distinguish the male and 

 the female elements except by the external shape of the follicle 

 as already described. 



(1) The cells which divide amitotically in the genital follicles of the silk-worm 

 do not belong to the cycle of sexual cells as above described and this confirms the 

 opinion of vom Rath (29, II) who says that " Dem Mitosen gegeniiber haben die 

 Amitosen durchweg einen mehr oder weniger deutlich erkennbaren degenerativen 

 Character. Die Mitose hat sich keineswegs aus der Amitose entwickelt, so dass die 

 letztere den urspriinglicheren Theilungsmodus darstellte." 



