DEVELOPMENT OE THE OVARIES IN THE BLOWFLY. 419 
germinal chamber (. Keimfach ). He was followed by Prof. Huxley 
(10, 11), Sir John Lubbock (19), Claus (8), and others. Stein 
enunciated the view' that the function of the terminal chamber is 
the formation of germ-yelks ; but he does not regard all the cells 
in the chamber as germ-yelks. Sir John Lubbock went a step 
further and wrote as follows : — “ In their earliest stage, the egg- 
cell and the vitelligenous cells cannot be distinguished from each 
other, and no one, I think, who has carefully examined the upper 
part of the egg-tube in any Hemipterous or Dipterous insect can 
fail to be of the same opinion.” 
I agree entirely with Sir John Lubbock in this, that all the 
cells in the terminal chamber are alike ; but when he concludes, 
“ The egg-tube contains, indeed, at this end, cells which are 
neither vitelligenous nor egg-cells, but which are capable of 
becoming, under certain circumstances, either one or the other,” 
I cannot agree with him, and my reasons will appear in the sequel. 
The Egg-chambers . — This term was first applied, I believe, by 
Brandt (6) to that portion of the egg-tube which contains definite 
ova. In some insects each egg is formed from a single cell ; this is 
so in the Orthoptera ; such ova are designated by Brandt panoistic. 
In other insects several cells are concerned in the formation of 
the ovum ; these ova he termed meroistic. 
In the meroistic egg Brandt calls the lowest cell the egg-cell, 
the others he terms nutrient or yelk-cells. 
The part played by these nutrient cells is a matter upon which 
there is great divergence of opinion. Brandt’s view, which has 
been generally adopted in text-books and widely accepted, is this: — 
The egg-cell in the meroistic egg is the only cell enclosed by the 
chorion, and the nutrient cells remain outside and ultimately 
disappear. These are supposed to be in some way concerned in 
the nutrition of the egg-cell. The great increase in the size of 
the egg-cell is due to the deposition of yelk-granules within it, 
around its nucleus, wdiich Brandt regards as the germinal vesicle. 
Similar changes also occur in the panoistic egg, wdiich only differs 
from the meroistic in the absence of the nutrient cells. 
Weismann (26) maintains, on the other hand, that all the cells, 
the nutrient as well as the egg-cell, are enclosed in the chorion, 
and that they all take part in the formation of the yelk, ultimately 
fusing into a single mass ; and this, as I shall show hereafter, agrees 
with my own observations. 
With regard to the import of Brandt’s egg-cell there is less 
