DEVELOPMENT OF TRICHOGRAMMA EVANESCENS. 161 
sections through the egg, the former at a time when most 
nuclei are present, the latter when fewest are present and 
just before multiplication begins again. PI. 11, fig. 12, ha& 
thirty-eight nuclei in the section; PI. 11, fig. 14, has thirty. 
Counts of a large number of sections yield similar results, 
though the total number of nuclei in a number of blastoderm 
stages varies a good deal. From PI. 11, fig. 12 to fig. 14, it 
will be noticed that the egg has broadened and contracted in 
length a good deal. Measured roughly from the camera 
lucida drawing, PI. 11, fig. 12, is a centimetre longer than 
the much older stage PI. 11, fig. 14. We then realise that 
two curious processes take place at this time ; one, the expul- 
sion of as many as fifty nuclei, the other, an obvious 
shortening and broadening of the egg. Explanations for 
both occurrences are difficult to formulate. In cases where 
no shortening can be shown to have occurred it is equally 
true that no lengthening has taken place, so that it remains 
correct that the developing egg departs from the proportions 
which it had when laid. A relative shortening always occurs,., 
i. e., in comparison of lengths and breadths of the eggs at 
different stages, for PI. 11, fig. 8, is one and three-quarter 
times as broad again as PI. 11, fig. 12, and a little shorter. 
PI. 11, fig. 13, is the later stage of the blastoderm. The egg 
has become relatively broader and shorter, and important 
changes have been taking place in the nuclei. It has already 
been remarked that in this egg fifty-three of these have been 
extruded. The germ-cells now stain quite faintly, but their 
arrangement is still unaltered. Most of the blastoderm 
nuclei in PL 11, fig. 13, are the same as those in PI. 11, 
figs. 12 or 21, but others show differences. Many of them 
have lost their small spherical granule, which was directed 
centrally, and in these the large nucleolar mass has shifted 
from its position in the periphery of the nucleoplasmic wall 
(PI. 11, fig. 21a) to the middle of the nucleoplasmic zone 
(PI. 11, fig. 13a, 2 and 3). The latter fig*ure is much 
enlarged and shows three stages in the alteration of the 
nuclear arrangement. At a later stage these changes become 
