40 Mr. H. J. Carter 0}i the Spongozoon. 



is one [monociliated boclj] in particular, which has two spines 

 or ear-like points projecting backwards, one on each side of 

 the root of the ciliuni (pi. 1. fig. 12), and this was the kind 

 which I first discovered and described ; but, confounding it 

 "with cells not possessing these spines (because I then thought 

 the spines might be accidental prolongations of the sarcode), 

 I did not give it this character." 



That I might have been right in this conjecture, the poly- 

 morphic nature of the whole of this body will presently show. 



In June 1866, Prof. James-Clark read a paper before the 

 Boston Natural-History Society " On the Spongise ciliatEe as 

 Infusoria flagellata, &c." (Mem. voL i. pt. 3, reprinted in 

 Annals, Feb. 1868), in which (p. 21, footnote) he conceives 

 that the two spines or ear-like points represent the lines en 

 jirojile of a " membranous cylindrical collar" which he had 

 observed to exist round the ciliura of the monociliated cell in 

 Leucosolenia hotryoides^ of which most satisfactory delineations 

 are given in his plate 1. figs. 41-44, together with that of 

 several species, fluviatile and marine, of similar animals that 

 live independently in groups or singly, sessile and pedicelled, 

 respectively, apart from the sponge altogether. In the latter 

 Prof. James-Clark most sagaciously demonstrates the exist- 

 ence also of this "membranous collar" — observations which 

 have been further confirmed as satisfactorily by Mr. Kent's 

 descriptions and delineations of several of the same kind of 

 Infusoria that he found in a pond at Stoke-Newington, in the 

 neighbourhood of London (Monthly Microscop. Journal for 

 Dec. 1871, p. 261, pi. cv.). 



Returning, however, to Prof. James-Clark's " footnote," he 

 adds, " that Carter did not always find these ' two spines,' may 

 be explained by the fact that the membranous collar, as I am 

 inclined to believe the ^ spines ' to be, was retracted, since I 

 have frequently observed this to happen in the case of Leuco- 

 solenia when it was disturbed." 



That is as much as to say that the " collar " is polymorphic ; 

 and herein is the explanation of what I have above quoted 

 from my paper of 1859, viz. that " I then thought the 

 spines might be accidental prolongations of the sarcode," — 

 a fact which is still further confirmed by my paper of 1871 

 (Annals, vol. viii. pi. 2. figs. 17 & 18), wherein it is not only 

 stated that every part of the sponge-animal is polymorphic, but 

 the "collar" itself in the figures mentioned may be observed to 

 be transformed into two pseudopodial tentaculiform processes 

 for seizing particles of food, like those of an Actinophrys or of 

 an Acineta. 



Hence the "collar" maybe cup-like around the base of the 



