402 Mr. Hogg's Observations on the Spongilla fluviatilis, 



but which, from its having neither polypes nor stellate pores, I consider to be 

 a species of Sponge and not an Alcyonium. In this opinion Ellis, Solander*, 

 and Montagu t were likewise agreed. I will therefore bestow the more ap- 

 propriate name of Spongla Cydonia, or the Quince Sponge, upon this sub- 

 stance of Donati, of Linnaeus, and of Pallas. 



Should, however, any future doubt be raised with respect to these seedlike 

 bodies (sferette) described by Donati, or should it be hereafter attempted to 

 be shown that the production itself is strictly an Alcyonium, this would not in 

 any way invalidate my statement, because the testimony of Dr. Ehrenberg at 

 all events decides the actual existence of sporidia (Sporangien) in certain Sea 

 Sponges :{:, and in all probability they, as well as sporules possessing for a 

 short period the locomotive faculty observed by Dr. Grant in several others, 

 will be found at the proper season of the year common to, and more or less 

 abundant in, every species of the Spongice Marince. 



Now as to the currents of water : If these do indisputably take place inde- 

 pendent of the respiration or other function of any marine insect, or worm, or 

 crustacean, or molluscous § animal parasitically nestled within the specimen 

 of Spongia, I must consider that they are most likely caused by an endosmosis 

 and exosmosis of fluids, in the manner I have already mentioned when descri- 

 bing the analogous currents of the Spongilla : and if they always occur in all 

 those Spongice Marince which are furnished with oscules, in the same constant 

 and uniform manner that Professor Grant has informed us they do in a few of 

 the more common species, that is to say, if the endosmose or entering fluid 

 should be always found to flow in by the pores, and the exosmose or expelled 

 one to issue out from the oscules ; these facts then would only present an ana- 

 logy with what is effected in the same regular mode by the sap in the higher 

 plants, where the entering sap rises throughout the plant by one set of ves- 



* Ellis and Solander, Zooph., p. 183. t In Wern. Mem., vol. ii. part 1, p. 118 and p. 69. 



I Similar sporidia are delineated at a. and b. of the figs. 1 & 2 in tab. 157. vol. iv. Zoologia Danica 

 (edit. Havniae, 1 806.) They are referred by the editor to a sort of Alcyonium, but which I must clearly 

 account as a species of Spongia ; and in support of my opinion, consult the observation of the learned 

 editor at p. 42 of the same volume. 



§ I may just remark that Pliny attributed the presence of Mollusca in the Sea Sponges to a cause 

 the very reverse of the fact ; i. e. " vivere esci, manifesto conchae minutse in his (Spongiis) repertse os- 

 tendunt." Vide Nat. Hist., lib. ix. cap. 69. 



