352 ME. LUBBOCK ON THE OVA AND PSEITDOVA OF INSECTS. 
that each egg-germ has its own peculiar viteUiferous duct, and that the duct is obliterated 
when the egg has received a sufficient amount of yelk. 
I could not see in the common germ-chamber more than one sort of cell, except that 
near the posterior end some few are evidently changing (Plate XTII. fig. T) into egg- 
cells ; and I conclude, therefore, that each of the cells in the germ-chamber is capable of 
becoming either vitelligenous or egg-cells. Those which develope themselves into egg- 
cells gradually swell, and their nucleus also increases in size and becomes the germinal 
vesicle ; after awhile a small cell-like macula makes its appearance in this latter. 
The common germ-chamber is at its posterior end somewhat contracted, and at this 
place one or two narrow egg-germs generally lie transversely across, occup}-ing the whole 
width of the tube. The next egg-germ is somewhat square-shaped, as are the three 
following ; the seventh is somewhat barrel-shaped ; and the eighth shows on one side 
the projection which is so conspicuous in the mature egg, and on which the micropyle 
is situated. I found also at this period (end of September) some few egg-tubes in wliich 
the projection was also commencing in the penultimate chamber. In the four anterior 
egg.germs the germinal vesicle occupied a central position, but in the more matiue 
egg-chambers it laid alternately, first on one side and then on the other, close to the 
layer of epithelial cells. It is worthy of remark, that in all my specimens the lateral 
projection was situated on the same side as the germinal vesicle. 
In the oldest egg-germs the yelk contained numerous granules and small oil-globules. 
In each ovary there are five egg-tubes. 
In the Coleoptera, excepting the Geodephaga and Hydradephaga, we find the same 
type of ovarian tube as in the Hemiptera, but the terminal germ-chamber is generally 
smaller in proportion. The cells contained in the germ-chamber are apparently of the 
same nature as in the Hemiptera, and probably therefore secrete part of the yelk-sub- 
stance. I have not yet, however, met with the yelk-duct. Since, however, I became 
familiar with this structure in Nepa, &c., I have been able to examine but le-s^ Coleo- 
ptera. 
In Telephorus (Plate XVI. fig. 4) the epithelial cells are small and indistinct, but in 
a Galeruca I found them very large. 
I have examined only lew species of Coleoptera, since Stein has devoted so much 
attention to them, that, as far as the female generative organs are concerned, there is no 
order with which we are better acquainted. 
In the Homoptera I have examined Aphrophora spumaria. Coccus hesperidtou, and 
C. persicm-. Professor Huxley {1. c.) has described a species ol ApMs, and Professor 
Leuckart three or four allied forms. All these present the same tjpe ol ovaiy as the 
Hemiptera; but the terminal germ-chamber is generally smaller, and the cells contained 
in it much less numerous, being in fact, in C. Jiesperidmn, only three in number. In- 
deed in this genus, as there is only one egg in each tube, there is in fact a group of 
vitelligenous cells to each egg-chamber ; and this form of ovary forms an intermediate 
link between the types found in the Hemiptera and the Hymenoptera. 
