14 THE BRITISH SPONGES. 



its way unquestioned among naturalists in general, and 

 was admitted unhesitatingly into elementary works of the 

 highest character ; * but it should be remarked, that the 

 authors of them added no other confirmation of it than what 

 we may allow is due to the fact of the impression of its 

 truth made on the minds of able and judicious men, by 

 the many proofs of it which Dr Grant had adduced. The 

 testimony of Dutrochet, and of Audouin and Milne-Ed- 

 wards to his accuracy is more valuable, for the former of 

 these eminent naturalists verified the existence of the cir- 

 culation through the River Sponge ; and the latter had 

 seen the phenomena on which the theory rests in the 

 sponges of the shores of France, f And although I am 

 well aware of the doubts which have been recently raised 

 on the subject, from the experiments made on the River 

 Sponge by Mr John Hogg, | — experhnents which I shall 

 afterwards mention in detail, — yet I cannot share in those 

 doubts, for even as this sheet passes through the press, I 

 and my family have had the pleasure of observing the cir- 

 culation distinctly in the Halichondria papillaris, Flem. ; 

 and it is with unfeigned satisfaction that I find myself in a 

 position to bear witness to the minute accuracy of Dr 

 Grant's description of the phenomena accompanying it 

 The current issues from the oscula in a continuous stream, 

 which is agitated like boiling water ; and minute granules 



• See Fleming's Brit. Animals, p. 519. Roget's Bridgewater Trea- 

 tise, i. p. 151-4. Grant's Outlines of Comp. Anatomy, p. 8. Milne- 

 Edwards in the 2d edition of Lamarck's Anim. s. Vert. ii. p. 535. 

 Stark's Elem. of Nat. History, ii. p. 424. Mantell's Wonders of Geo- 

 logy, p. 458. Sharpey in Cyclop. Anat. and Physiology, i. p. 612. Gray 

 in Synopsis of British Museum, p. 57. 



f Hist. Nat. du Litt. de la France, i. p. 76. 



\ Liniiean Transactions, xviii. p. 390, and p. 402. 

 4 



