ON THE SPERMATOGENESIS OF THE SILK-WORM. 131 



We have also met with a similar large cell in the testes of 

 the wild silk-worm (fig. 16), Papilio xuthus L. (fig 15), P. mach- 

 aon, L., P. alcinous, Klug., but not in Antherea yamamai, Gu£r. 

 Men., Caligura japonica, Moore., Rhodia fugax, Butl., etc. So 

 it seems evident that in the genital glands of Lepidoptera, such 

 a cell connecting the younger genital elements with the follicular 

 wall, although not constant, is not of rare occurrence. < r) 



I. The Formative Stage. The genital cells of this stage or the 

 primary germ-cells, are situated near the blind end of each tes- 

 ticular follicle and are arranged concentrically round the sup- 

 porting cell as already mentioned (figs. 7, 11). The youngest 

 primary germ-cells are round with distinct chromosomes and 

 nucleolus (fig. 4). When the supporting cell enters the testicular 

 follicle and becomes connected with the genital cells, the latter 

 assume a conical shape (figs. 11, 18), the apices of which are 

 connected with the protoplasmic processes of the supporting cell. 

 The nucleus of these germ-cells is always situated at the basal 

 part of the cell, corresponding exactly to the young genital 

 cells of Pyrrhocoris apterus described by Henking (15). In each 

 follicle are seen many generations of the primary germ-cells 

 showing the various stages of typical karyokinesis. In figs. 17-22 

 are represented various stages of division of primary germ-cells. 

 Fig. 17 and 18 show cells in the resting stage; their nuclei 

 present a spherical shape with a distinct nuclear wall. 

 Chromatins are scattered in fine reticulum. Nucleolus is 

 clearly tp be seen in the centre of the nucleus. In a pre- 

 paration fixed by the Flemming's strong chrom-osmium acetic 

 acid solution and stained by Hermann's safranin-gentiana-orange 

 the nucleolus is found to be suspended in the chromatin-net 

 as one or two globules, and consists of small round chro- 

 matic bodies. 



In the nucleus represented by fig. 17, is seen only a 

 single nucleolus in the matrix of which small round granules 

 are clearly to be seen, while in other cells (fig. 18), the 



(1) Chclodkowsky's ( 6 ) observation on the testis of a Diptera, also confirms 

 the presence of such a large cell in the follicle, but it seems to be of an entirely 

 different nature from that of the silk-worm, as it divides mitotically. 



