STRUCTURE OF THE OVARY. 
199 
Phthirius, three cords spring from each ovarian tube, instead of one as 
in most insects. Leydig 2ra considers this cord to be hollow, while most 
other authors describe it as solid in the insects they have examined. 
Neither in the locust or the cricket have I seen any trace of an interior 
cavity. The cord is covered by an external membrane, very thin, and 
apparently homogeneous, except for the nuclei, which enter into its 
composition, and appear in stained preparations as dark bodies project- 
ing above the general level of the membrane, which, in short, very 
closely resembles the tunica propria of the Malpighian tubes. In the 
interior of the cord are numerous granular oval nuclei (Fig. 64 ch.), their 
long axes being nearly parallel with that of the cords. If a cord be 
teazed out with needles, each nucleus is found to lie in the middle of a 
spindle-shaped body, from either end of which a thread-like process runs 
out lengthwise of the cord. In what manner these threads terminate 
I do not know. This cord runs to the rounded tip of the ovarian tube, 
which begins quite abruptly, quickly attaining twice the diameter of the 
cord in Anabrus (Fig. GI), or three or four times in the locusts. From 
the tip downwards the tube is divided into compartments, each of which 
contains a single egg. The lower we go, the wider the tube and the 
more advanced in development the egg. Between every two fully- 
developed compartments the tube is somewhat constricted. In Anabrus, 
a long narrow piece sometimes intervenes between two adjacent com- 
partments. In locusts, at least, the tubes are narrowed by a marked 
constriction just before they open into the oviduct. In Anabrus (Fig. 
64 «), the commencement of the upper end of the ovarian tube proper is 
marked by the transverse direction of a few oval nuclei. Immediately 
below these are found rounded nuclei, and among them lie a few cells 
which have already assumed the distinctive characters of eggs ; these 
latter cells are larger the lower their position. In this part of the tube 
(Fig. 64 a b) there is no distinct division into compartments. The cor- 
responding region in locusts differs in that at the upper end or very tip 
I could distinguish only one kind of cells, which had clear nuclei and 
distinct nucleoli. Lower down some of the cells become larger than 
their fellows, and partly surrounded by them ; still lower the large cells 
appear isolated, larger, and completely inclosed by a layer of cells that 
form a perfect epithelial follicular wall. 
The remaining lower and largest part of the ovarian tubes is divided 
into distinct compartments or follicles. As we proceed downward in 
our examination of the tube we see that the egg-cells, which were at 
first spherical, become elongated in the direction of the axis of the tube, 
while at the same time the nucleus becomes indistinct, and the proto- 
plasm of the original cell charged with yolk granules, the deutoplasm 
of Fdouard van Beneden. 270 
It. will thus be seen that the development of the eggs in Caloptcnus 
Lcydig: Zum feineren Ban <ler Arthropoden. Miiller's Archiv., 1855, p. 472-3. 
Composition et Signiiication do 1'oBuf. Mem. cour. Academie Iioyalo Bclg., T. xxxiv, p 1 (1870.) 
