48 Mr. H. J. Carter on the Spongozoon. 



" ampullaceous sac " (Annals, 1857, 1. c), but that the groups 

 are situated in excavations of what I termed, in 1849, the 

 "intercelMar substance" (that is, in " mere cavities," haying 

 "no lining wall," Annals, 1872, I.e. p. 76), but opening into 

 the chamber which I have delineated between tlie " investing 

 membrane" and the "parenchyma" (fig. 1, 1857, I. c), Pro- 

 fessor James-Clark's " cytoblastemic mass." 



All that I can state in reply to this is, that I have figured 

 faithfully (/. c.) what appeared to me to be the rim of a circular 

 opening in material belonging to the spherical group of spon- 

 gozoa. Furthermore, in my journal, under date " 26th March 

 1857," stands a figure of one of these spherical groups of 

 spongozoa which I well remember to have observed in 

 the watch-glass 1)7/ itself^ with the cilia still vibrating in its 

 interior and the aperture closed, after that state had arrived 

 when, as I have described (p. 29, I. c), the whole of the soft 

 parts of the young Sj^ongilla^ apparently from starvation, 

 leave the spicular structure and become dispersed about the 

 watch-glass. 



That I did not figure this cell I also well remember to have 

 arisen from diffidence on account of the great number of new 

 and startling facts that were then revealed to me. 



Of this being fact, I now ha^'e no longer any doubt ; and 

 thus we had an " ampuHaccous sac " entirely isolated from 

 the parenchyma (" cytoblastemic mass," Prof. James-Clark) 

 of the sponge, that is, by itself in the watch-glass. 



With no aperture, it is true ; but then we know that this 

 can be closed or opened as required : yet it still retained the 

 globular form; and hence the question then comes, whether 

 this globular form was retained by an intercellular substance 

 or sarcode uniting the spongozoa together, or whether this 

 union arose from an amalgamation of the polymorphic sarcode 

 of which their bodies are respectively composed. I incline to 

 the former ; and this is what I should designate as the " am- 

 pullaceous sac." 



But here we arrive at a point which is most perplexing, if 

 it be not almost entirely beyond our powers to decide, — viz. 

 that state in which the living material assumes forms so deli- 

 cate and so fugitive that we are inclined to deny to them 

 characters even in a remote degree of that solidity and per- 

 manence which by comparative coarseness becomes so evident 

 to our senses in the more advanced developments of ordinary 

 tissues. 



In short, are we to deny the existence of a cell of inter- 

 cellular substance binding the Avhole of the spongozoa into a 

 spherical community, or not ? And if so, where is the proof 



