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



inclined to believe belonged to them, and which the statement made by so 

 high an authority as Baron Cuvier, in his first edition of the Regne Animal*, 

 induced me partly to acquiesce in. Since the year 1823, I have not had an 

 opportunity of re-examining any of the Sea Sponges in a living state and in 

 their native element. But the subsequent investigations of Professor Grant, and 

 of other observers, have clearly determined that they are not endowed with the 

 least irritability. 



Being so wedded to my former opinion of the animality of all Sponges, and 

 being by my researches on the River Sponge at length assured of its vegeta- 

 bility, I then began to imagine, agreeably with the suggestions expressed by 

 Montagu f, De Lamarck;}:, and Bell§, that it might possibly be quite a dif- 

 ferent substance from the Sea Sponges ; and if so, these latter might be yet 

 esteemed of a true animal nature ||. However, still more recent and minute 

 comparisons of many of these, as preserved in several collections with the 

 Spongilla, have compelled me to abandon that idea ; for I cannot find any 

 more solid ground for it, than for holding that one genus of the Fungi, as 

 MeruUus, belongs to a perfectly distinct division of nature, from another 

 genus of the same order, for instance, Agaricus; and as all who should 

 behold them would immediately and unhesitatingly acknowledge both the 

 one, and the other, to be a true Mushroom or Fungus; so we are equally 

 obliged to admit, that the Spongia and Spongilla are in fact both real Sponges ; 

 indeed there scarcely is even so much as a generic difference between them ; 

 and in this, with the earlier naturalists Dr. Fleming^ coincides, for he places 

 both kinds in one and the same genus, Halichondria. 



Both the Freshwater and the Sea Sponges are furnished with a skeleton of 

 fibres interlacing, crossing, and anastomosing with themselves ; generally also 

 strengthened with those singularly crystallized particles termed spicula ; with 

 a parenchymatous soft portion or jelly ; with a fine and transparent envelop- 



* See torn. iv. p. 88. 



t For the observations of Montagu, refer to the Wemerian Memoirs, vol. ii. part 1, p. 76. 

 X Anim. sans Vert., torn. ii. pp. 98, 99, edit. 1816. 



§ See Mr. Bell's Remarks on the Animal Nature of Sponges in the Zool. Journ., vol. i. p. 204. 

 II This is alluded to by Dr. Johnston, in his note on the nature of Sponges, at p. 325 of Brit. Zooph. 

 % See History of British Animals, p. 524. 



