with some Remarks on the Nature of the Spongiæ Marine. 405 
no irritability or powers of contraction and dilatation, no palpitation, and no 
Sensation whatsoever. 
Surely, then, we cannot any longer esteem these natural substances to be 
individual animals, or even groups of animals, in which not one organ, or a 
single function or property peculiar to an animal can be discovered*! And 
that they are in fact neither the nidus or matrix, nor the fabrication or pro- 
duction of any animal, the mode in which Professor Grant witnessed their 
locomotive sporules beginning to germinate, to increase, and to develop 
themselves after the forms of their parent structures}, must be to all tho- 
roughly satisfactory. 
It is to me nevertheless a subject not altogether certain, and one worthy of 
some consideration, in what order of plants the Sponges ought to be included. 
Linnæus, as it will be remembered, in his Flora Lapponica, edit. 1737, and 
Flora Suecica, edit. 1745, placed the Spongia lacustris and S. fluviatilis in his 
class Cryptogamia, and order Lithophyta; but in the earlier editions of his 
Genera Plantarum, and of his Species Plantarum, he distributed both the Sea 
and Freshwater Sponges in his class Cryptogamia and order Alge, 
In a work of a late date, intitled, “A Natural Arrangement of British 
Plants," by Mr.S. F. Gray, both the Spongilla and the Sea Sponges are classed 
in the Fam. 2. Thalassiophyta, which belongs to his Subseries I. Plante Cel. 
lulosæ Aphyllee g. 
Professor Link has very recently stated, in the work § quoted in the begin- 
ning of this letter, that they should be separated from the Zoophytes and re- 
placed amongst the 4/ge. But my own observations lead me to conclude 
that all the Sponges would be more correctly arranged in an intermediate 
order between the 4{gæ and the Fungi; for although they are with some rea- 
son considered by many naturalists to be allied to certain of the Algæ |, still 
* So must we at length agree with the illustrious Greek naturalist, that the Sponges resemble plants 
in every respect: ó d oxdyyos, ravrehws Éowe rois gurois. Aristot. Hist. de Animal. lib. viii. s. 2. 
t See Edinb. New Phil. Journ. for 1827, p. 137. | 
À See vol. i. p. 353 of Mr. Gray’s work published in 1821. i 
$ See Annales des Sciences Naturelles, Seconde Série, tom. ii. (Botanique), p. 328. 
I| M. Link however (op. cit. p. 330.) admits, “ il est vrai que la structure des Eponges est très dif- 
férente de celle des autres Algues; mais la structure de ces dernières plantes présente déjà des modi- 
fications si frappantes qu'on ne doit pas s'étonner d'en rencontrer une de plus.” 
