200 REPORT UNITED STATES ENTOMOLOGICAL COMMISSION. 
and Anabrus is identical with that observed in other insects, 271 for which 
I refer the reader to Waldeyer, 272 Leydig, 273 and particularly to the elabo- 
rate and accurate memoir of Dr. Ludwig. 274 
I wish to describe somewhat carefully the relation of the egg to the cells 
of the follicular wall in the locust. If a bit of the wall of one of the largest 
follicles be spread out on a slide and colored with carmine it will be seen 
that it is composed of very large and beautiful cells, Fig. 20. The cells 
are for the most part pentagonal in outline, a few being hexagonal. The 
nuclei are very large, taking up a great part of the cells, in the center 
of which they lie. They are slightly oval, though departing but little 
from a circular outline. They are darkly colored by carmine, and are 
filled with innumerable small granules, which prevented my ascertaining 
whether there is any nucleolus, though in many cases there seemed to 
be one of considerable size. A transverse section through the whole 
follicle, such as is reproduced in Fig. 19, shows that the cells form a 
single continuous layer, Ep, around the egg, Eg. Examined with a higher 
power, Fig. 16, such a section reveals the form of the cells. The free or 
outer surface of the epithelium, Ep, is nearly flat, while the side towards 
the egg, Eg, is dome-shaped. Between the epithelium and the egg there 
is a layer, Sh, of finely-granulated and very pale substance that is not 
colored by carmine or h ajmatoxiline. This layer has its outer surface 
hollowed out into little cups, each of which is intended to receive the 
dome-shaped end of one of the epithelial cells, as is shown very plainly 
in Figs. 10 and 19, which represent sections in which the epithelium is 
artificially raised from t he granular layer. In the normal condition the 
cells rest directly on the layer, and there is no clear space, as indicated 
in Fig. 10. It is to be added that the layer in question consists of three 
strata: 1, a very delicate external membrane, which rests against the 
epithelium ; 2, the middle granular portion ; and 3, a fibrous stratum, 
which assumes a roseate hue after staining with carmine, and which lies 
next the egg. The layer is formed in the follicles, and is probably se- 
creted by the follicular epithelium. It is not to be found in the upper 
part of the ovarian tube. If I am not mistaken, it passes over with the 
egg into the oviduct, being destined to form part of the shell. I cannot 
help suspecting that it is this structure which has given rise to the opin- 
ion that, at least in some insects, the wall of the egg follicle passes off 
with the egg to form part of the shell. 
In the egg proper of locusts, Figs. 10 and 19, Eg, the enormous masses 
of nutritive yolk deserve special mention, though I have been unable 
to determine their relation to the protoplasm of the egg. 
The ovarian tubes have further an external tunic, which I have studied 
"'Excellent diagrams of the development of eggs in insects are given in Gegenbaur's Grundziige der 
Vergleichenden Anatomie. 2 Aufl., p. 463, fig. 121, and an even better figure of Vanessa urticoe is given 
by Waldeyer in Strieker's Handbnch der Lehro von den Geweben, p. 5G3, fig. 195. 
272 Waldeyer: Eierstock und Ei, Leipzig (18T0), p. 86, and especially p. 90. 
m Iieydigi Eierstock und Samentascbe der Insecten. Nov. Act. Caes. Lcop., xxxiii (1867). 
174 H. Ludwig : Semper's Arbeiten. Bd. I. 
