310 Mr. H. J. Carter on the Animality of Freshwater Sponges. 



diffluens (Muller) * ; that which chiefly accompanies No. 4 is of 

 the figure given by Dujardin, to which I have already had occa- 

 sion to allude ; while the vibrating bodies themselves, when com- 

 bined, take on the appearance of minute Proteans, and every 

 particle of the fixed transparent granulo- gelatinous matter, which 

 serves as a nidus for the whole, appears to be endowed with the 

 power of continually extending, retracting, and altering its 

 shape. 



I have further observed, that the granulo-gelatinous trans- 

 parent matter has in some places arranged itself into the forms 

 of full-sized spicula, disposed in linear continuation, over-reach- 

 ing each other side by side, just as they are seen in the fibrous 

 structure of the old sponge ; their surfaces however are not yet 

 silicified ; nor should I expect this to take place, as my experi- 

 ments have been conducted with distilled water, had not Dr. 

 Grant mentioned that siliceous spicula were formed in the gem- 

 mules of Spongilla which he nourished with rain-water. 



Thus does every step towards the ultimate structure of the 

 Freshwater Sponge, every form that is taken by the living mat- 

 ter of which it is composed, appear still more nearly to approxi- 

 mate it to the nature of the genera of Ehrenberg's Pseudopodia. 



In a subsequent communication received from the author, he 

 observes, that he has confounded two species under the head No. 2, 

 and that the bright green coloured species there mentioned is 

 distinguished from all the rest by having a crust of double- 

 pointed smooth spicula round its seed-like bodies. He supposes 

 this to be Spongia lacustris (Linn.), Spongilla friabilis (Lam.). 



Further, he observes respecting the animality of the Freshwater 

 Sponges, that the animals of which they are but a congeries are 

 identical with the infusorium Proteus; 1st, because they are 

 composed of a semi-transparent gelatinous matter ; 2nd, because 

 this gelatinous matter is endowed with the power of altering its 

 shape and of locomotion ; 3rd, because in it are seen transpa- 

 rent cells (contracting vesicles) of various diameters from 1 -9000th 

 part of an inch to a mere point (which he formerly supposed to 

 be sphinctral orifices), dilating and contracting themselves as in 

 other animalcules; and 4th, because this gelatinous matter is 

 provided with greenish yellow granules moving with, and espe- 

 cially characteristic of both the Proteus and the animal of the 

 sponge. 



He regards the Proteus as being more active in changing its 

 shape, &c. than the animals of the sponge when first torn from 

 each other, from the habits of the former having been vagrant 



* Blainville, Manuel d'ActinoIogie (Atlas, pi. 11. fig. 12). 



