504 Royal Society : — 



living embryos, ov perhaps nymphs. I examined several specimens, 

 and found the female generative organs quite in accordance with his 

 descriptions and figure. They are, however, undoubtedly true 

 ovaries, though the thickness of the outer membrane gives them a 

 deceptive appearance. If the egg-tubes are torn asunder, egg-germs 

 will be found in them, as in the corresponding organs of any other 

 Ilymenopterous insect, and presenting as usual a transverse constric- 

 tion, with the vitelligcnous cells in the upper division. 



In the four matrices the eggs are cylindrical and somewhat curved, 

 and under the action of water, one end of each swells up considerably. 

 In this they present an approach to that form which attains its 

 greatest development in Cynips. 



The ovaries of Coccus hesperidum have been rightly described by 

 Prof. Leydig as consisting of a long tube on each side opening by 

 a very short oviduct into the egg-canal. The whole surface of the 

 tube is covered with egg- germs in all stages of development. The 

 collateral glands are very small in C. hesperidum, but are well de- 

 veloped in C. PersiccB. 



In its earliest stage the egg-follicle is a simple projection of the 

 ovarian wall, which becomes gradually pear-shaped, and may then 

 be seen to consist of a structureless outer membrane, a layer of 

 epitheUal cells, and three vitelligenous cells, with very delicate 

 walls. 



The walls of these cells soon disappear, and even the nuclei are 

 often scarcely distinguishable, but acetic acid will generally make 

 ihem more visible. Leuckart has given a correct account of these 

 bodies, and indeed of the whole process ; but Leydig apparently mis- 

 took them for germinal vesicles. 



The epithelial cells line the membrane constituting the egg-follicle. 

 As usual, they are columnar in the lower chamber and flattened and 

 scattered in the upper. They contain a circular nucleus. The action 

 of water causes them, and indeed the whole upper chamber, to swell 

 considerably. The columnar epithelial cells of the lower chamber 

 contain generally small greenish globules, apparently identical with 

 the small oil-globules which form so large a part of the yolk, which 

 is, I therefore suppose, in part secreted by them. 



The germinal vesicle makes its appearance after the vitelligenous 

 cells, and generally after the egg-follicle has lost its original pyriform 

 shape. It is about -0008 in diameter. The macula germinativa is 

 single, and somewhat granular in appearance. 



The oil-globules make their appearance about the same time as the 

 germinal vesicle, and soon become the most conspicuous part of the 

 egg. They are at first very small, but in a mature egg the larger 

 ones are as much as "0016 in diameter. The oil-globules may often 

 be seen with their sides much flattened by mutual pressure, and 

 must therefore possess a somewhat compact pellicle. 



Very soon after the appearance of the first oil-globules, the egg- 

 follicle loses its pear-shaped form, the basal part swells, and is sepa- 

 rated from the apical part containing the nuclei of the vitelligenous 

 cells by a constriction. It now perfectly resembles the egg-chamber 



