Germ-Cells in Chrysonielid Beetles. 261 



wliieh lies outside of the pole-disc and is destined to become a part 

 of the blastoderm. The central nucleus of this trio (6) has pushed 

 a part of the pole-disc outward and forced the granules into a cap 

 (a half -moon in section) which extends half-way up its sides. The 

 granules are now not as widely separated from one another as we 

 found them in a previous stage (Fig. 3) ; they have become more 

 densely packed due to the pressure exerted by the migrating pole- 

 cell nucleus in its effort to break through the "Keimhautblastem" 

 (compare Figs. 4, 18 and 19). The neighboring pole-cell nucleus 

 (Fig. 20, a) is in a somewhat more advanced stage; it shows that 

 the granules covering its outer surface become, in part, pushed away 

 from this region and gradually extend around its sides until they 

 cover all of the surface except the innermost portion. All of the 

 granules of the pole-disc do not adhere to the pole-cells, some being 

 left behind within the remains of the "Keimhautblastem." 



A surface view of the posterior end of the egg at this stage shows 

 plainly eight pairs of pole-cell nuclei (Fig. 13) ; an enclosing layer 

 of the dark staining granules is suspended within each of these 

 enabling one to distinguish easily the pole-cell nuclei from the 

 adjacent blastoderm-nuclei. This paired condition of the pole-cell 

 nuclei is accounted for by the fact that since the division of the eight 

 nuclei of the previous generation, the daughter nuclei have not yet 

 separated. In one case where the daughter nuclei have drawn some 

 distance apart from each other (Fig. 13, h) a wide strand of cyto- 

 plasm is seen connecting the two. A few of the neighboring 

 blastoderm nuclei, which have passed near the edge of the pole-disc, 

 have also carried with them some of the granules which are seen 

 embedded in their adjacent sides (Fig. 13, a). The nuclei of the 

 blastoderm are slower than the pole-cell nuclei in reaching the 

 surface, and have hardly begun to protrude when the latter have 

 almost, or, in some cases, entirely separated from the egg (Fig. 9). 

 Each pole-cell nucleus is now completely surrounded by a layer of 

 granules more dense at the side than at either end (Fig. 21). After 

 reaching the position last described (Fig. 9) all of the pole-cell nuclei, 

 except in a few cases where one of them has been delayed (Figs. 26 

 and 22) become entirely separated from the egg, and lie in a single 



