460 MAUD D. HAVILAND 
but in the course of this work three stages in the formation of 
the blastula were observed (Text-fig. 4), and therefore a partial 
description of them is now given. 
A shows the egg soon after segmentation has begun. 
B represents the blastula already formed, and comparison with 
the figures of Silvestri and Gatenby shows no essential differ- 
ence, save that in Charips the germ-cells are indistinguish- 
able from the rest of the primary layer. In c the egg is seven 
hours old, and it will be seen that the nucleoplasmic masses 
TEXT-FIG. 4. 
Early stages in the segmentation of the egg. x900. ch.m. = extruded 
chromatin; 6/. = blastoderm: t.m. = trophic membrane. 
in the blastocoele have disappeared, and that there has been 
considerable displacement of the nuclei on the right-hand 
side. Certain nuclei are arranged in a manner that suggests 
that we have here a stage similar to that which Gatenby has 
indicated as the first appearance of the endoderm. Moreover, 
an involucre, apparently of cellular structure, surrounds the 
egg, and contains nuclear staining elements distinct from the 
degenerating chromatin masses shown in the previous figure. 
As intermediate stages are lacking it is impossible to say with 
certainty how this involucre arose. 
Nearly all my available material was in the stage figured 
as B, but the membrane did not appear in it and there was no 
sign of the delamination described by Silvestriin Enceyrtus. 
