378 ANDREWS. (Vor. XII. 
interlaced with, or joined themselves to, other filaments or net- 
works met with. 
The greatest number of spinnings seemed to be from the cells 
near the polar globules, and this region of the egg, it will be 
remembered, was the first to spin as well as the most active at 
all times. In this region was shown also most tendency among 
the peripheral filaments to ramification and anastomosis, espe- 
cially when they crossed the path of certain spinnings from 
the polar bodies, shortly to be described ; most capriciousness 
in their optical qualities, and interchange of fluid and viscid 
states, with greatest inclination to stiff viscidity. 
At time of closure of the cleavage cavity pore, the cells 
about it flatten markedly, and at the same time become irregu- 
lar in optical contour ; the spinnings are then very strong and 
viscid-looking, and the protruding regions are seen to be attached 
by them to like regions of other cells. There follows much the 
same series of optical appearances among the filaments as when 
sister cells are drawn together, and for these reasons it seemed 
not unlikely that the filaments were actually instrumental in 
closure of the space between the cells. 
After a closure of the space is effected, the general “ ecto- 
derm”’ cells, as they multiply, become gradually flattened exte- 
riorly beneath their common pellicle, so that all seeming of 
intercellular clefts is obliterated. At the same time their 
inner ends protrude somewhat within the cavity, so that here 
there are marked intercellular clefts. 
These clefts are crossed from cell to cell by delicate, hyaline, 
filose extensions of the cell pellicle; and from the ends of the 
cells, which are plainly more fluid than the outer portion, are 
produced other and much longer threads, which extend even 
across the whole cavity, binding the most distant cells into 
physiological and direct continuity. 
Up to this time the external spinnings of the mass pellicle 
have been progressively somewhat less profuse. When the 
blastula has a sufficient number of cells for its free-swimming 
state these outer spinnings rather suddenly cease, but burst 
forth again over the surface of the pellicle as hair-like pro- 
cesses which quickly show irregular, contractile, or waving 
