198 ON THE DISTINCTION OF AN ANIMAL, &C. 



vegetable. Buffon therefore observed that plants may be 

 accounted sleeping animals, an idea which has been al- 

 most universally followed by succeeding naturalists, and 

 » which if it cannot from observation be proved to be cor- 

 rect, is nevertheless ingenious and highly poetical. 



On the whole however it appears that animals are to be 

 distinguished by the existence of an absorbent intestinal 

 cavity, and of a nervous system, and that both these marks 

 become indistinct in the infusoria and polypes. It fol- 

 lows therefore that the infusoria and polypes, which are 

 the most simple of all animals in structure, approach nearest 

 to the vegetable nature. 



