ESSAY ON SPONGES, 



73 



tion is so extremely limited, as to create doubts of 

 its existence ^. 



The actual distinction between animal and ve^ 

 getable 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 between them ap- 

 pears to consist in tlieir constituent parts. 



By chemical analysis, there appears to be an in- 

 fallible character of specific distinction, by which 

 they are with certainty recognised f . That cha- 

 racter, therefore, discovered in all animal matter, 

 has been proved by chemical decomposition to ex- 

 ist in sponges Motion, as already observed, is not 

 essential to animality ; and in their inertion, zoophy- 

 tes, especially sponges, approximate so nearly to ve- 



* Vitality is not affected by separating any part of zoophytal 

 animals^ no more than in Hydra: each fraction contains an 

 equal portion of vitality independent of connexion. In the 

 higher order of beings^ vitality is limited. 



f " I need not/' says Mr Ellis, when speaking of the chemi- 

 cal experiments on keratophyta, " nlention any other to the 

 curious, than the great quantity of volatile salts that may be ex- 

 tracted from them, and the strong smell they yield when burnt;, 

 of roasted oysters." 



X The odour produced in the combustion of sponges, and other 

 zoophytes, is similar to that of other animal substances, mixed 

 with a peculiar marine odour, well exemplified by oysters roasted 

 in their shells ; and which is very different from the effluvia of 

 burning vegetable matter. 



