with some Remarks on the Nature of the Spongiæ Marine. 381 
Sponges. And I much suspect, that were these bodies belonging to several 
more kinds of Spongia magnified 400 or 500 times, what have hitherto been 
taken for cilia* will prove to be either papillz similar to those in the sporules 
of the Spongilla fluviatilis, and that the supposed vibrations in the water are 
in reality only endosmose and exosmose currents through the membranes of 
these bodies and their papillæ ; or else, if when slightly magnified they appear 
like the true cilia of animals, they will under a higher power of the micro- 
scope be ascertained to be small tubules, as well through which, as through 
the membranes of these germlike bodies, the same reciprocal action of fluids 
takes place, and thereby most probably effects their remarkably similar move- 
ments. 
Moreover, since I have already attempted to describe the locomotive germ- 
like bodies of the River Sponge, and have alluded to those of the Sea Sponge, 
the sporules of the club-shaped Ectosperma amongst plants, and the sponta- 
neous movements of the Globe Volvox among the Infusorians, it only remains 
to consider, for the sake of comparison, the moving germs or gemmules of 
some animal which strictly belongs to the Zoophytes. For this object, I will 
select the locomotive gemmules of the Alcyonium gelatinosum (Linn.) , as 
they have been so recently discovered by Dr. A. Farre, and by whose kind- 
* Since Dr. Grant is evidently in error as to the tentacula of the Sertulariæ being ciliated, (see 
Edinb. Phil. Journ. vol. xiii. p. 101,) I cannot but think that he is under the like mistake respecting 
cilia being also present upon the locomotive sporules of the Sea Sponges. Both Dr. Johnston in his 
Brit. Zooph., p. 43, and Mr. Lister in his memoir in the Phil. Trans. for 1834, p. 377, have subse- 
quently ascertained that the Sertulariæ have no cilia. The family Sertulariade belonging to my 
Unosculous subclass of Zoophytes, 1 propose to arrange in an order called Noditentacula, from their 
tentacles being furnished with nodi, small knots or projections. Such minute processes, without the 
aid of a very good microscope, and in a clear, strong, and equalized light, may very easily deceive the 
eye of the observer. And I may remark, that my proposed order corresponds with a part of Dr. 
A. Farre's Polypi Nudibrachiati; but here it will be evident that this term is inapplicable to those 
Zoophytes whose tentacula or brachia are rough with small knots or nodules, and are furnished with 
irregular hairlike projections according to the observations of M. Trembley on the Hydre, and of 
Mr. Lister on the Sertularie. 
T It is the Halodactylus diaphanus of Farre; the Alcyonidium gelatinosum of Johnston (Brit. Zooph.) ; 
the Ulva diaphana and Alcyonidium diaphanum of many botanists. It is singular that it should have 
been so lately classed among plants, for its polypes were long ago mentioned in Solander and Ellis's 
work on Zoophytes. See also the note of Mr. Gray in his paper on Sponges, at p. 50 of the Zoolo. 
gical Journal, vol. i. 
