Mr. H. J. Carter on the Freshwater Sponges of Bombay. 91 
It might be as well to notice here that the yolk-like contents 
of the dried seed-like body, with but slight modifications, undergo 
the same changes as those of the fresh one. If the former be 
divided with a sharp knife or lancet, and a portion of its contents 
picked out on the point of a needle and put into water, it swells 
out after a few days into a gelatinous mass ; its component parts, 
i. e. its germs and semi-transparent mucilage, begin to evince 
signs of active life,—a successive development of proteans follows, 
and threads of the semi-transparent mucilage shoot over the sur- 
face of the watch-glass in the manner I have just described. 
So far the elements of the sponge are developed from the con- 
tents of the seed-like body after forcible expulsion ; we have now 
to examine them after having issued in their natural way. 
If a seed-like body which has arrived at maturity be placed in 
water, a white substance will after a few days be observed to have 
issued from its interior, through the infundibular depression on 
its surface, and to have glued it to the glass; and if this be ex- 
amined with a microscope, its circumference will be found to con- 
sist of a semi-transparent substance, the extreme edge of which 
is irregularly notched or extended into digital or tentacular pro- 
longations, precisely similar to those of the protean, which in 
progression or in polymorphism throws out parts of its cell im 
this way (Plate IV. fig. 2c). In the semi-transparent substance 
may be observed hyaline vesicles of different sizes, contracting 
and dilating themselves as in the protean (fig. 2d), and a little 
within it the green granules so grouped together (fig. 2 e) as 
almost to enable the practised eye to distinguish 7m situ the pass- 
ing forms of the cells to which they belong ; we may also see in 
the latter their hyaline vesicles with their contained molecules in 
great commotion, and between the cells themselves the mtercel- 
lular mucilage (fig. 2/). 
If this newly-formed sponge be torn up, its isolated cells as- 
sume their globular or passive form or become polymorphous, 
changing their position and their locality, by emitting expansions 
similar to the proteans or polymorphic cells developed after a 
forcible expulsion of the contents of the seed-like body, and dif- 
fering only from them in being more indolent in their move- 
ments. 
Habits of the Sponge-cell—tIn describing the habits of the 
sponge-cell so far as my observations extend, I shall first confine 
myself to those which are evinced by it in, or when torn from, 
the fully-developed structure of the sponge, and subsequently 
advert to the habits of the polymorphic cells or proteans, which 
are developed from the contents of the seed-like body when for- 
cibly expelled. 
The sponge-cell when in situ is ever changing its form, both 
