55 

l am indebted to Professor J. T. Parrerson for my material. This 
consisted of a brood of female parasites of Copidosoma which emerged 
on September 4, 1913. The ovaries of part of these were dissected 
out in Rısser’s solution on the same day when they emerged, and 
another lot was similarly treated on September 12. Ovaries were 
fixed in Carnoy’s solution, Gitson’s mixture, and Mevxs’ modification 
of Fiemmine’s fluid. They were embedded in paraffin, cut longitu- 
dinally two microns in thickness, and stained in various ways. The 
best results were obtained with material fixed in Carnoy’s solution 
and stained with iron-haemotoxylin followed by eosin. 
Original Observations. 
As in most other insects the two ovaries of Copidosoma consist 
of rows of oöcytes in various stages of growth—the oldest and largest 
near the posterior end, and the youngest and smallest at the opposite pole. 
Before the oögonia enter the growth period each becomes surrounded 
by a follicular epithelium and is provided with a group of nurse cells 
wich likewise are enclosed by a cellular envelope. Increase in size 
takes place synchronously in both the nucleus and the cytoplasm of 
oöcyte and a number of stages in this process are illustrated in the 
accompanying figures. In the Fig. 4 a strand of cytoplasm (n.s.) 
is shown extending forward to the nurse chamber, and it is evidently 
by means of this pathway that nutritive material is conveyed to the 
oöcyte. During the growth period the nurse cells decrease in size 
until they occupy but a very small space and the follicular epithelium 
becomes very much attenuated (compare Figs. 1 and 2). 
The fully developed oöcytes (Fig. 1) are more or less vase-shaped 
with a broad base (posterior), a narrow ‘ waist-line,’ and a slightly thicker 
distal (anterior) portion. They are not so long and slender as those 
illustrated by Sttvusrri, but perhaps this shape is atteined later when 
the eggs are laid. Within the oöcyte are two conspicuous bodies. 
Fig. 2. Longitudinal section through young oöcyte (0) and accompanying 
nurse cells (7.c.). The chromatin in the oöcyte nucleus is in the form of irregular 
chromosomes. >< 800. 
Fig. 3. Longitudinal section through slightly older odcyte. The nurse cells 
have been omitted. The chromosomes in the oöcyte nucleus are apparently united 
near their ends in pairs. >< 800. 
Fig. 4. Longitudinal section through a still older oöcyte showing the nutritive 
strand (n.s.) extending to the nurse chamber. Only two nurse cells (n.c.) are 
included in the figure. >< 800. f.e. follicular epithelium; %. keimbahn-chromatin; 
n. nucleus of oöcyte; n.c. nurse cells; .s. nutritive strand; 0. oöcyte. 
