68 OPINIONS AND DISCOVERIES 



Since, however, there are some Fungi and Algae, more 

 especially among the Oscillatorise, which, in the process of 

 decomposition, give out the same odour ; and since it is 

 admitted that chemistry furnishes no absolute test to enable 

 us to detect the veiled members of either kingdom of or- 

 ganized matter, the question of the rank and position of the 

 sponges remains undecided. And although it has its im- 

 portance, for in the framing of a natural system, the in- 

 troduction of a spurious member, or the absence of an ana- 

 logue, may mar and perplex the whole, yet the question 

 will continue, and must be one of words merely, unless the 

 disputants sliall agree on a definition by which the line 

 drawn between the tv/o kingdoms can be made more real and 

 tangible than it is in natiu-e. If the possession of an in- 

 ternal digestive sac, or indeed of any limited organ for 

 any function, — if the power of extracting nutriment from 

 organized matter only, — if the capability of motion, or if 

 the presence of nerves or of irritability, be considered essen- 

 tial to animal life, then the sponges are not so endowed : 

 but they mil be considered to be at least animated in the 

 opinion of those who believe that a basis similar to horn in 

 texture and composition, intermixed with a fluid resem- 

 bling gelatine, indicates some other than a vegetating life, 

 which, in none of its acknowledged productions, has ever 

 so combined the materials of its existence. There is, how- 

 ever, nothing to forbid us believing, with the earlier na- 

 turalists, that the sponges may belong to neither kingdom ; 

 — nay the very discussion leads to the conjecture that they 

 do actually constitute a middle race, in whose features we 

 can sometimes trace a predominance now of the animal 

 and no\\' of the vegetable nature. Few on examining the 



