of the Freshwater Sponges in the Tanks of Bombay, 307 
length is about one quarter of the diameter of the body, and ap- 
parently corrugated like the neck of the entozoon Cysticircus 
longicollis. These transparent little sacs (the genimules of Grant 
and Hogg ?) are sometimes filled with green matter. They ap- 
pear to be able to adapt themselves to any form that may be 
convenient for them to assume, and when forcibly separated from 
each other (by tearing to pieces a minute portion of the sponge 
under water in a watch-glass), the isolated individuals may be 
seen to approach each other, and to apply themselves together 
in twos and threes, &c., and so on, until, from a particle only 
discernible by the microscope, they assume the form of an aggre- 
gate visible to the naked eye, and such a portion, growing and 
multiplying, might ultimately reach the size of the largest masses 
adhering to the sides of the tanks at Bombay. They appear to 
belong to the genus Amoeba of Ehrenberg. Dujardin has re- 
cognized them, and they are correctly figured (as they appear 
under a lens of one-tenth of an inch focus) in Johnston^ s ^ British 
Sponges,^ p. 61 ; — as well as certain filaments, which the day 
after a piece of sponge has been treated in the way which I have 
just mentioned, may be seen extended from them, terminating 
or not in little transparent bulbs ; floating, or fixed by their ex- 
tremities, branching irregularly, long or short, each branch ter- 
minating or not in a bulb, and presenting similar pedicellated 
bulbs here and there in its course ; when fixed on the watch- 
glass, disposed irregularly in straight lines intersecting each 
other, — radiating from a common centre or bulb, or in the form 
of an areolar membrane; frequently moniliform, as if they grew 
by the addition of cells to their free extremities. 
The aggregated position of the animals I have described, im- 
bedded in the transparent tissue of the sponge, bears a great re- 
semblance to that of some of the Compound Tunicated Animals ; 
especially in their ultimate development into a mass, intersected 
in all directions by canals, to allow of the presence of that ele- 
ment which is necessary for their existence, — the freedom they 
possess in the early part of their life, of moving through the 
water or creeping over the surfaces of solid bodies, and their 
ultimate destination of becoming permanently fixed in a granulo- 
gelatinous mass, secreted or formed by themselves. 
There is also a curious fact connected with the vitality of the 
Freshwater Sponges, and I think it also prevails with the Sea 
Sponges, for it was by observing the latter and their seed-like 
bodies, in the amorphous species, that I was first led to notice it. 
It is, that they may be taken out of their natural element, dried, 
and kept for months, without losing their vitality. This I have 
inferred from observing the sponges attached to the rocks on the 
upper parts of the tanks, which are uncovered for many months 
