FROM A VEGETABLE. 193 



faculty, the former depending on the contraction of the 

 muscular fibre, which again depends on the influence of 

 the nerves. Neither is it in the presence of azote as a 

 chemical constituent of animal bodies, for this is allowed 

 also to exist, though in a much smaller degree, in vege- 

 tables. 



There remain however three characters of distinction 

 which appear more capable of support ; and I shall ac- 

 cordingly adopt them in stating that vegetables are to bo 

 distinguished from animals 



1st. By the elaboration for their nourishment of fluid 

 matter received by an absorbent external surface, whereas 

 in animals it is received by an absorbent internal surface; 

 this last being called the intestinal cavity, and its inner 

 surface being furnished with innumerable pores or vessels, 

 which Boerhaave considered as real internal roots. 



Sndly. By the exhalation of oxygen and absorption of 

 carbonic acid, whereas animals exhale this last and ab- 

 sorb oxygen. 



Srdly. By the \vant of a nervous system and conse- 

 quently of sensation, whereas animals possess both*. 



It has been objected to the first of these three cha- 

 racters that an intestinal cavity has not yet been per- 

 ceived in the infusoria, and that in the polypes this 

 cavity may be turned inside out, like a glove, without 

 the ordinary functions being disturbed. But it is possi- 



* Mirbel has attempted to add another peculiar characteristic to vege- 

 tables, namely, that it is the office of them alone to transform inorganic 

 matter into organized living bodies, whereas animals feed only on orga- 

 nized matter. This remark appears however to be more ingenious than ac- 

 curate, since many animals of the lower tribes and some Heieromerous 

 Coleoptera have been observed to feed on inorganic matter. 



O 



