DEVELOPMENT OF TRICHOGRAMMA EVANESCENS. 159 
all affinity for stains. I feel quite sure that there are at least 
six germ-cells in the blastoderm stage, but often one counts 
more during later stages, in some cases as many as nine. 
Mitotic division of the germ-cells between the blastoderm 
stage and the adult larva I have not yet found, and I feel the 
more certain of this at the period of germ layer formation, 
because one never finds the germ-cells assuming a greater 
affinity for chromatin dyes as they would do if they were in 
the prophases of mitosis. From the time of their segregation 
onwards to the formation of the larva the germ-cells are 
resting. At the time when the larva has swallowed almost 
all the yolk (see PL 12, fig. 38 and p. 25) the germ-cells seem 
to become active again, but though I believe they begin to 
divide by amitosis, I have not enough material of this stage 
to feel quite certain of this. The germ-cells have the ap- 
pearance of fig. 36 of PI. 12, and the granules (6r.), which 
one can in rare cases discover, may be the remains of the 
germ-cell determinant. In PL 11, fig. 21, the structure of 
the germ-cells and the blastoderm nuclei is shown. The 
arrangement of the latter is very peculiar and characteristic. 
The nucleus consists of an oval nucleoplasmic zone, PL 11, 
fig. 21 A. ( N.P .) in which is placed excentrically, and always 
towards the periphery of the blastoderm, a large chromatin 
nucleolus ( M.G . ). This large granule is rounded on the side 
touching the edge of the nucleus and generally more irre- 
gular on its inner surface. Placed on the periphery of the 
nucleus, and always pointing towards the central region of 
the egg, is a granule, or two, much smaller, and quite sphe- 
rical ( G.R.C .) (P. 11, fig. 21). This remarkable arrangement 
and the peculiar orientation of the nucleus and its granules 
is quite clear. Observe also the transverse section in PL 11, 
fig. 12, and in fig. 17. 
This arrangement is quite constant and typical, but in one 
blastoderm alone did I find a difference, and this lay in the 
presence of other granules (0. G.) near the large main 
nucleolar granule (M. G.) y PL 11, fig. 16. It may be possible 
that the blastoderm was younger than its fellow drawn in 
