360 ME. LUBBOCK ON THE OVA A2vT) PSEUEOTA OF INSECTS. 
fusiform. At this period also they contain numerous very small greenish granules 
(Plate XVIII. fig. 6), vrhich have probably been secreted by the inner surface of their 
walls ; and as these granules cannot be distinguished from the smallest oil-globules, I 
presume that these also are secreted by the epithelial cells. 
The columnar epithelial cells of the lower chamber are almost always visible, but the 
flatter ones lining the upper chamber can seldom be seen unless the specimen is put in 
water. 
The germinal vesicle very soon makes its appearance, but it is veiy curious that though 
it is (when seen at all) very distinct indeed, yet in many instances in which I should 
have expected to see it, it could not be discerned. Compare for instance Plate X^ III. 
figs. 3 and 4 ; in the latter the germinal vesicle and its nucleus are quite plain, while m 
the former, which was taken from the same animal, was in the field of ^iew at the same 
time, and is in other respects rather more developed, not a trace of gernrinal vesicle 
could be seen. 
We are therefore compelled to believe, either that the germinal vesicle is ur some 
instances absent, which is extremely improbable, or that the time of its appearance 
varies considerably. Of course I do not rest this conclusion upon the examination of 
this one specimen only, but from the comparison of a great marry. In the youngest 
specimen in which I ever found the germinal vesicle, the egg-follicle was pyr-iform. 
•0032 in its greatest diameter, and about -0058 in length. The ger-mirral vesicle was 
•0008 in diameter. It varies very little in dilferent specimens either in appear-ance or 
size, the largest being ‘0009 and the smallest •0006 ; neither do these dilfererrces appear 
to have any reference to the state of maturity of the egg-follicle. 
In the former part of my paper it has been merrtioned that the \itelhgenous cells and 
the egg-cell appear in insects generally to be modificatiorrs of the epithelial cells. The 
same is probably the case in Coccus ; but in spite of my anxiety to throw light orr this 
part of my subject, I was unable to do so. In one specimen, however, a few of the cells 
in the lower part of the upper chamber were larger tharr usual, and had a rrrore distirrct 
nucleus. The uppermost of these cells had very much the appeararrce of the gerrrriiral 
vesicle. If, however, this change takes place rapidly, there are eVdeirtly so marry chances 
agaiirst our detecting the transitional forms, that it seenred desirable to record airythirrg 
which may possibly be a link in the chain of evidence. 
I did not find in Coccus any distinct rnembrairous errvelope sinroirnding the gerrrriiral 
vesicle, and it is therefore probably very soon absorbed, as in the Orthoptera and marry 
other insects. 
The later history of the germinal vesicle is equally obscure, lor it soon disappears 
from view. At first I thought it was hidden by the oil-giobules ; but this can hardly be 
the case, because I never once succeeded in making the germinal vesicle visible by 
pressure when I could not see it otherwise. The largest specimen of the germinal 
vesicle I ever saw was very faint as it was disappearing, and I never saw two cells which 
could have resulted fronr the division of the germinal vesicle. Professor Leydig pro- 
