440) A. J. NICHOLSON 
I consider that the substance of the inner wall is no longer 
in globules but has formed a continuous gelatinous layer. 
Obviously a fibrillar structure could not be produced from 
such a layer in the manner described above. 
When the egg is freshly laid the inner wall is still a thick 
gelatinous structure, but after some hours it hardens and in 
sections is seen to form a thin dark-coloured membrane lying 
immediately under the outer wall. 
As the inner wall appears between the oocyte and the 
follicular epitheliumm the question arises as to which of these 
secretes it. The cytoplasm of the oocyte is already occupied 
in the production of yolk and the follicular epithelium secretes 
the outer wall at a later period, so that whichever of these 
structures form the inner wall is also capable of producing an 
entirely different substance. 
Over the greater part of the egg it is impossible to determine 
whether the inner wall is secreted by the follicular epithelium 
or the oocyte; but the stopper, which is merely an isolated 
portion of the inner wall, is formed between the follicular 
epithelium and the nurse-cells. The inner wall must therefore 
be secreted by the follicular epithelium, and after this has 
been produced the epithelium changes its form of activity 
and secretes the outer wall. 
DEGENERATING HKGG-FOLLICLES. 
The degeneration of a certain number of egg-follicles seems 
to be a normal occurrence in the ovary of A. maculipennis. 
Commonly this degeneration takes place when the follicles are 
just entering on the second period of growth, but not infre- 
quently at a much earlier stage the primary follicles are found 
to be represented by a small mass of degenerated cells sur- 
rounded by a loose and much-folded tunica propria. The 
significance of this degeneration is not clear. I have been 
unable to detect the presence of any bacteria or other organisms, 
and the fact that degenerating follicles are almost invariably 
to be found in small numbers in ovaries, but that all, or even 
