90 Mr. H. J. Carter on the Freshwater Sponges of Bombay. 



shoots out digital or dentiform processes ; and that of the small- 

 est, the vermiform protean (fig. 1/), which progresses after the 

 manner of a worm. 



They are all (like the cells of the sponge) composed of a cell- 

 wall, within which are round or ovoid, green, translucent gra- 

 nules, varying in size and number ; and one or more hyaline 

 vesicles. 



The green granules, although appearing to move over the whole 

 surface of the protean in its active state, are, nevertheless, when 

 it is in its globular or passive state, found to be confined to the 

 upper and inner part of its cell- wall. Sometimes these granules, 

 from their smallness, can hardly be recognized individually, and 

 only appear in the form of a nebular mass; this is frequently the 

 case in the difflueDt proteans and in those inferior to them in 

 size ; at other times they are few in number and all the largest 

 of their kind. 



The hyaline contracting vesicle, of which there is seldom a plu- 

 rality in the smaller proteans, appears to be uninfluenced in its 

 presence or development by the state of the green granules, since 

 there is almost always one at least present, and in the enjoyment 

 of great activity. 



Such are the changes in the contents of the seed-like body 

 which are witnessed, under this mode of development, with re- 

 ference to the germs ; we have now to turn our attention to the 

 semi-transparent mucilage, which holds the germs together in 

 their insulated groups, or binds them down singly to the surface 

 of the vessel in which they are contained. 



This semi-transparent mucilage appears to be identical with 

 the intercellular mucilage of the sponge ; it exhibits the same 

 phenomenon of ever undergoing a change in shape, but, as I 

 have said before, I am not aware of its possessing this property, 

 independently of the presence of the cells and minute germs 

 which are contained in it ; neither do I know how it comes into 

 existence, i. e. whether it be the product of the germs themselves, 

 or whether it be eliminated with them, in a more elementary 

 transparent and invisible form, from the cells of the seed-like 

 bodies. Be this as it may, threads of it soon appear in straight 

 lines extending over the surface of the watch-glass from portion 

 to portion (Plate IV. fig. 1 h), and from object to object starting 

 off from different points of an isolated germ — or from any point 

 of a thread of it already formed — sometimes disposed in a flat 

 reticulated structure over a spiculum, or on the surface of the 

 glass — occasionally as broken portions like the ends of threads 

 thrown together without union or order, and not unfrequently 

 bearing minute germs in their course either at irregular distances 

 from each other, or arranged like a string of beads. 



