ON DEVELOPMENT OF ATYEPHIRA COMPRESSA. 405 
gelegten Eier positiv kernlos sind.” But how it dwindles 
away is a question not yet decided. The germinal vesicle, 
which is at first always in the centre, is often found to be 
somewhat excentric in position in an egg little advanced, but 
never at the periphery. Commonly, however, I have seen the 
wall of the vesicle indented and rather indistinct. Whether 
this shows the transitional stage from the nucleated cell to a 
cytode or not I cannot venture to affirm. All that I can say 
is that the germinal vesicle disappears while the egg is still in 
the ovary. 
To sum up, then — 
1. The ovarian egg of Atyephira compressa originates 
from the inner lining epithelium of the ovary, and is, at the 
beginning, a cell with a nucleus, and one, two, or rarely 
three, nucleoli. Later, the deposition of the yolk takes place 
endogenously. 
2. The protoplasm of the egg collects at two points, the one 
around the nucleus and the other at the periphery. The 
former spreads out like rays towards the latter, and unites 
with it. 
3. The germinal vesicle grows less vigorously than the 
egg. It disappears speedily when the egg attains a certain 
size. 
4. The ripened egg is covered by two membranes, the one 
formed by the hardening of the peripheral protoplasm of the 
egg, while the other is formed by the product of the epithe- 
lial cells of the oviduct. Between these two membranes a 
certain quantity of a clear transparent liquid is found. 
5. The freshly-laid egg is unfurnished with a nucleus, and is 
therefore a cytode. 
Laying of Eggs. — When the eggs are fully grown, and 
ready to be laid, the region of the oviduct appears white by 
the reflected light through the carapace. The section of such 
an epithelium will show that the lining cells are very much 
elongated (fig. 15). If an animal in such a condition is put 
into a vessel and watched for a day or two the laying of eggs 
can easily be observed. This generally takes place in the early 
