Mr. H. J. Carter on the Freshwater Sponges of Bombay. 87 
The granules are round or ovoid, translucent, and of an eme- 
—_ or yellowish green colour, varying in diameter below the 
Tzb00 th part of an ‘inch, which is the average linear measurement 
of as largest. In some cells they are so minute and colourless 
as to appear only under the form of a nebular mass, while in 
others they are of the largest kind and few im number. 
The hyaline vesicles on the other hand are transparent, colour- 
less and globular, and although variable in point of size like the 
green granules, are seldom recognized before they much exceed 
the latter in diameter. They generally possess the remarkable 
property of slowly dilating and suddenly contracting themselves, 
and present in their interior, molecules of extreme minuteness in 
rapid commotion. 
When living and isolated the sponge-cell is polymorphous, its 
transparent or non-granular portion undergoing the greatest 
amount of tr ansformation, while its semi- -transpar ent or eranular 
part, which is uppermost, is only slightly attracted to this side 
or that, according to the point of the cell which is in the act of 
being transformed. 
The intercellular substance, which forms the bond of union 
between the cells, is mucilaginous. When observed in the deli- 
cate pellicle, which, with its imbedded cells and granules, it forms 
over the surface and throughout the canals of the sponge, it is 
transparent ; but when a portion of this pellicle is cut from its 
attachments, it collapses and becomes semi-opake. In this state 
the detached portion immediately evinces a tendency to assume 
a spheroidal form; but whether the intercellular substance partici- 
pates in this act, or remains passive while it is wholly performed 
by the habit of the cells which are imbedded in it, to approximate 
themselves, I have not been able to determine. 
Seed-like Bodies.—The seed-like bodies occupy the oldest or 
first-formed portions of the sponge, never its periphery. They 
are round or ovoid according to the species, and each presents a 
single infundibular depression on its surface which communicates 
with the interior. At the earliest period of development in which 
I have recognized the seed-like body, it has been composed of a 
number of cells united together in a globular or ovoid mass (ac- 
cording to the species) by an intercellular substance similar to 
that just described. In this state, apparently without any cap- 
sule, and about half the size of the full-developed seed-like body, 
it seems to lie free, in a cavity formed by a condensation of the 
common structure of the sponge immediately surrounding it. 
The cells of which it is now composed appear to differ only from 
those of the full-developed sponge-cell in bemg smaller, in the 
colourless state of their germs, and in the absence of hyaline 
vesicles ; in all other respects they closely resemble the sponge- 
