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 in 

 this way (Plate IV. fig. 2 c). In the semi-transparent substance 

 may be observed hyaline vesicles of different sizes, contracting 

 and dilating themselves as in the protean (fig. 2 d), and a little 

 within it the green granules so grouped together (fig. 2 e) as 

 almost to enable the practised eye to distinguish in 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 intercel- 

 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. — In 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 



