LttCT. II. j DEFINITION OF A PLANT. 49 



every part of the animal, even to the extremities 

 of the feelers, which are also hollow. It is thus 

 bruised; the soluble parts are absorbed, and the 

 remainder is thrown out by the mouth, which is 

 also the anus of the Polypus. If a Polypus be 

 turned inside out, that which was the external 

 surface becomes now the stomach, and performs 

 the functions of it, but still the food is taken 

 within the animal; it is also taken at intervals 

 only, and must remain within the animal some 

 time to undergo the process of digestion, before any 

 part of it can be absorbed by the lacteals and car- 

 ried into the circulation : a Polypus, therefore, 

 cannot be said to be nourished in the same man- 

 ner as vegetables are, which is by continued ab- 

 sorption by the external surface. 



If, as I suppose, no exception can be found 

 to this remark, the characteristic which it points 

 out as distinguishing animals and vegetables is 

 very striking, and may properly form the leading 

 feature in the definition of a vegetable: " A 

 " plant," I would therefore say, " is a living or- 

 " ganized body, which requires food and air for 

 " its support, grows, propagates its species, and 

 " dies: and differs from animals, in being nourish- 

 " ed by continued absorption by its external sur- 

 " face/* An objection to this definition has been 

 anticipated by Mirbel, in combating the opinion 

 of Aristotle and of Boerhaave, that plants are 



VOL. I. E 



