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ME. LUBBOCK OK THE OVA AKD PSEUDOVA OE IKSECTS. 
The Neuroptera (with the exception of the Dragon-flies) ofier the next step towards 
the type which prevails in the Lepidoptera, &c. Each egg-chamber is generally divided 
by a constriction, the posterior portion containing the yelk, germinal vesicle, and germi- 
nal spot ; and the anterior part enclosing in Panorpa communis generally two viteUige- 
nous cells, in Psocus three, in one of the Le^toceridoe four, and in Chrysopa jyerlo. flve or 
six. Besides being few in number, the vitelligenous cells in the Neuroptera are some- 
what indistinct, especially in Panorpa, and do not present a well-deflned nucleus. 
In Panorpa also, and in one of the Leptoceridce, it seemed to me evident that the whole 
egg-cell, and not only the germinal vesicle, was equivalent to the -vitelligenous cell. 
In the Diptera* I have only examined CJieilosia, Eristalis^ Musca, and the Tipulidoe 
and CulicidoB ; nor am I aware of any other observations on the ovary of this order 
except those of Loew, which I have not been able to obtain, of Leuceaet on JPeio- 
phagus, and Swammerdam on Stratiomys, which latter refer rather to the external form 
than to the histological structure. Probably, however, we shall And in the remainder 
of the order, as in the forms already examined, that the ovarian tubes are very short and 
extremely numerous. In a small species of Glieilosia^ indeed (Plate XVI. flg. 9), there 
were as many as eight egg-chambers, but in Musca and Eristalis there are only two or 
three, and in Culex and Tipula only one or two. 
In all cases, besides the egg-chambers, there is a terminal germ-chamber. The layer 
of epithelial cells is early and strongly developed, and the constriction between each 
two egg-chambers is very deep. In many cases, indeed, there is a considerable interval 
between each two egg-chambers, which gives to the egg-tubes a remarkable and pecu- 
liar appearance. There is no constriction between the germ- and yelk-portions of the 
egg-chamber, but the two together form a round mass, which gradually becomes oval, 
and Anally more or less elongated, according to the shape of the mature egg. The 
vitelligenous cells are large, polygonal from mutual pressm’e, and in some cases provided 
with a distinct nucleus. 
It is worthy of observation, that this type of egg-formation is very different from that 
of Pulex^ or indeed of any other insects. The external membrane of the egg-tube may 
generally be seen forming a series of bridges, projecting from one egg-chamber to 
another. The vitelligenous cell which lies at the posterior end of the egg does not at 
first differ from the others. Gradually, however, it grows darker, and its nucleus 
becomes the germinal vesicle. It is, however, only in the two lowest egg-chambers that 
this, which evidently corresponds to what I have called the egg-cell, becomes much 
larger than the true vitelligenous cells. At this stage it appears to lose its true cell- 
wall and to become a mere yelk-mass, which, as the vitelligenous cells gradually dis- 
appear, absorbs the yelk-matter supplied by them, and Anally occupies the whole egg- 
chamber. 
In the early part of September the ovary of Eristalis tenax is a white body, shaped 
* Leuckaet and Willioh have described a partial segmentation as occurring in tbe eggs of Diptera; 
but this is probably a mistake, into wbicb they may have been led by the vitelligenous cells. 
