362 
ME. LUBBOCK OK THE OVA AKD PSEEHOVA OF IKSECTS. 
According to Dr. Leydig, the constriction separating the two chambers begins after a 
while to become less marked, and finally disappears, the egg itself being fonned in and 
filling both chambers, so that the contents of the upper chamber occupy the apical end 
of the egg, and form the commencement of the blastoderm. In this I have no doubt he 
is mistaken, and that M. Leuckaet’s account is correct, although I too have seen some 
instances which might account for his mistake. These, however, are quite exceptional ; 
and as a general rule, after the constriction is formed, the upper chamber ceases to gi'ow 
larger ; and as, on the contrary, the lower one continues to expand, it forms gradually a 
larger and larger fraction of the whole. After remaining of the same size for some 
time, during which the lower part has considerably increased, the upper chamber begins 
to diminish, and finally becomes atrophied. 
According to Dr. Leydig, if I understand him right, the three litelligenous cells, 
which he considers as germinal vesicles, divide and subdivide, carrying with them each 
time a portion of periplast, so that when the reunion of the two chambers takes place, 
the apical portion contains a number of nucleated cells, which together constitute the 
blastoderm. 
This description is entirely erroneous, as M. Leuckaet also has mentioned. Plate 
XVIII. fig. 7 shows a nearly full-grown egg, in the upper chamber of which the tlmee 
vitelligenous cells (e), larger indeed than at first, but otherwise unaltered, are plainly 
visible. This is no solitary instance, but is, on the contrary, the usual process. Moreover, 
if several large egg-follicles are placed in water, it wdl probably happen that the upper 
chamber of one, at least, will burst, and one or more of the vitelligenous cells will be 
pressed out. They then present a cloudy appearance, but no orifice could ever be seen 
in them. 
After having fulfilled their functions, and when the upper chamber is becoming atro- 
phied, the vitelligenous cells sometimes break up into small irregular balls, which 
become smaller and smaller, and finally disappear. 
The general cavity of the body of the female Coccus contains an immense number of oval 
green cells, which are apparently of vegetable nature. They are about -gwo in breadth 
and -go^o in length. Some specimens, however, are considerably longer, and present a 
constriction in the middle ; these are evidently undergoing transverse division. I have 
also found similar cells in the larvse at various ages, as at the beginnmg of J une and J uly. 
Almost always at the period when the vitelligenous cells have disappeared, and some- 
times earlier, a mass of these oval green cells may be found at the lower part of the 
upper chamber. As the upper chamber becomes atrophied, they find their way domi 
to the front of the egg. Thus we may say, almost without a metaphor, that the germs 
of future disease can be detected even in the unlaid egg *. I have scarcely ever found 
* Entozoa have been found in foetus, but not, so far as I know, in an egg which would have hatched 
properly. See Allen Thomson’s article ‘ Ovum,’ in Todd’s Cyclopsedia, p. 12. It is true that M. Kohd- 
MANN has described certain parasites as being produced from the yelk of Tergi^es, without ai’restiug the 
development of the embryo. M. Vogt, however, considers, with reason, that the supposed parasites are 
only detached cells, and not independent animals. 
