OF THE NATURE OF SPONGES. 35 



inal nature, though he believes them to be the very simplest 

 productions of their class.* 



The experiments and opinions of Cavolini coincide ex- 

 actly with those of Colonel Montagu published at a much 

 later period, but the English naturalist had evidently no 

 knowledge of Cavolini's excellent work. " With respect to 

 the nature of sponges," says Montagu, " there has been con- 

 siderable difference of opinion ; but, in the present era of 

 natural history, it is pretty generally allowed, that they are 

 truly of an animal substance, extremely torpid, and for the 

 most part, if not wholly, destitute of visible motion. With 

 considerable attention to some species taken fresh from the 

 sea, and others that I have examined in the cavities of their 

 native rocks, still immersed in their natural element, not 

 the smallest motion was perceptible, nor were there any ap- 

 pearances of internal action ; for such would have produced 

 some cmTents or slight agitations in the water, which must 

 have been perceived by the assistance of glasses. Action, 

 however, is by no means necessary to constitute an animal ; 

 for in many instances vitality is known to exist wdthout mo- 

 bility." 



" The actual distinction between animal and vegetable 

 life is, perhaps, so small and indefinite, that the physiologist 

 will scarcely venture to say where the one terminates and 

 the other commences ; the only material distinction be- 

 tween them appears to consist in their constituent parts. 



" By chemical analysis, there appears to be an infallible 

 character of specific distinction, by which they are with cer- 

 tainty recognised. That character, therefore, discovered in 



* Memoria per servire alia storia de' Polipi marini di Filippo Cavo- 

 lini, p. 266—272. Nap. 178.5. 



