STUDIES ON GERM CELLS ays | 
yolk formation proceeds, they gradually disappear until none 
- are visible except near the periphery in the posterior region. 
3. Secondary nuclei appear near the oocyte nucleus at an early 
stage of growth (fig. 27). They increase in number, finally 
completely surrounding the germinal vesicle (figs. 33, 34). They 
later become distributed throughout the oocyte especially near 
the follicular epithelium (figs. 37, 39). Their origin by budding 
from the oocyte nucleus, or by the immigration of epithelial 
cells seems improbable. The conclusion is reached that the 
oocyte nucleus gives off materials into the cytoplasm which be- 
come enclosed by a membrane and develop into nuclear-like 
bodies. The fate of the secondary nuclei was not determined. 
III. HISTORY OF THE NUCLEI AND GERM-LINE DETERMINANTS 
IN THE OOCYTES OF CERTAIN PARASITIC HYMENOPTERA 
AND HYMENOPTEROUS GALL-FLIES 
1. Copidosoma gelechiae 
In June, 1914, I published a short account of the growth of the 
oocyte in Copidosoma gelechiae with special reference to the 
origin of the germ-line-determinants. Since then two other 
accounts have appeared on the same subject, one by Martin (’14) 
on Ageniaspis (Encyrtus) fuscicollis, and the other by Silvestri 
(14) on Copidosoma buyssoni. I nave also been able to obtain 
and study a new lot of material. This makes it possible for me 
to add to my previous account and to clear up certain points 
about which differences of opinion have arisen. These poly- 
embryonic Hymenoptera are interesting principally because of 
the peculiarities in their embryonic development. We shall 
refer in this paper to two of these; (1) the history of the egg nucleus 
and (2) the origin and fate of the germ-line-determinants. 
Silvestri ('06—’08) has shown that a body which he considered 
the nucleolus of the germinal vesicle is present near the posterior 
end of the eggs of certain parasitic Hymenoptera. During 
embryonic development this body is segregated in a single 
cleavage cell until the seven-cell stage is reached; then, having 
disintegrated, its substance is divided between two cells. These, 
