J. BliONTE GATENBY. 
176 
must be received over the surface of the ovum, and it follows 
that the surface nuclei must be partly engaged in the taking 
up of the food matter. A glance at PL 11, fig. 7, and fig. 28, 
will show how enormously the egg has grown during develop- 
ment. Both figures are drawn to the same scale, and the 
embryo in PI. 11, fig. 28, had not yet begun to swallow food. 
All the food necessary for this growth has been derived 
through the surface of the embryo and of the developing egg, 
and without the help of yolk cells, which are so characteristic in' 
hexapod embryology. The form of nucleus in the blastoderm 
must be the one suited to the requirements of the developing 
embryo, and the occasional expulsion of whole nuclei, and 
the constant extrusion of the granule, is probably due to the 
fact that the nuclei become liyperchromatic. That this 
nuclear arrangement is artificial and temporary is shown, in 
the first place, because it is not found in the adult insect 
(follicle cells of ovary excepted) ; and secondly, because 
there is always a tendency for the nuclei to regain the 
normal reticulate arrangement. It is as if the forces which 
suppressed the usual chromatic arrangement were overcome 
now and again, but soon recovered their power. To illustrate 
this suggestion it may be mentioned that the changes shown 
in PI. 12, figs. 40-48 take place sporadically. Nuclei like 
that figured in PL 12, fig. 43, occurred in the embryos in 
PL 11, figs. 27 and 28 (A.), were absent in Pl. 12, fig. 33, 
but were common in PL 11, fig. 15 (N.N.), and were found 
to occur in a scattered manner right up to the formation^of 
the larva, when they became suppressed. It was particularly 
in the loose cells in the body cavity that such nuclei were 
found, and it seems fair to conclude that these are the cells 
which would be least affected by the metabolic influences 
surrounding the embryo. 
The occurrence of the modified nucleus in the follicle cells 
of the adult iu sect's ovary is due to the fact that such cells 
are exposed to somewhat the same conditions as the nuclei in 
the embryo, and are engaged in passing on food to the ovum 
(PL 11, fig. 9, FN.). 
