56 EVOLUTION OF LIFE. 



we see in the oyster, of opening its shell at the 

 afflux of the tide. This nervous power, how* 

 ever, if it be one, does not extend throughout 

 the whole of the vegetable system ; it is princi- 

 pally confined to the efflorescence, at the par- 

 ticular time in which it becomes unfolded, and 

 when it is about to fulfil the final cause of 

 its existence, in the production of fructifi- 

 cation. 



Admitting the possibility that something like 

 a nervous arrangement may exist in a few 

 species of vegetables ; in those which approxi- 

 mate the closest, to the first order of the animal 

 tribe; it does not, however, appear that the 

 anatomist has detected its existence, or the 

 physiologist explored its power, in that large 

 and intermediate class of beings, of fuci and 

 madrepores, which connect the higher orders of 

 vegetables, with the lowest of the animal king- 

 dom. The hydra, or semi-transparent polypus, 

 when examined in the best light, through the 

 strongest magnifying microscope, seems to be 

 nothing more than a granular substance, some- 

 thing like boiled sago, connected together into 

 a distinct and organised form by the medium of 

 a gelatinous substance. In the zoophytes, and 

 the lowest order of vermes, the whole of their 

 fabric is nearly of the same simple construction ; 

 the power of digesting, or assimilating the 

 ^natter of the medium in which they are placed, 



