PLANTS. 207 



impossible. Plants, on the contrary, have the faculty 

 of inhaling carbon and exhaling oxygen, retaining the 

 former as necessary to their vegetable existence ; so 

 that we may not suppose that plants are only useful, as 

 they please with their variety and beauty, or form a 

 portion of the nutriment of the animal kingdom, but by 

 the purifying influence they exert on the atmosphere, 

 are absolutely necessary for the continuance and comfort 

 of animal life. Experience, too, has shown how impor- 

 tant is their agency as articles of food ; most animals live 

 altogether on vegetables, comparatively few are so car- 

 nivorous as wholly to reject them ; and it is a well known 

 fact that all places destitute of vegetable life aro not only 

 uninhabitable, but also very unhealthy. 



Vegetation is, therefore, the precursor of animal life 

 in the economy of nature ; all animals, either directly or 

 indirectly are nourished by plants; and the vegetable 

 kingdom thus rendering such varied and important ser- 

 vice to the animal, may be truly said to touch closely on 

 its foundation. There is scarcely a plant that does not 

 nourish some animal ; almost all insects, for example, 

 live either in the perfect or in the larva state at the 

 expense of the plant upon which they are habitually found ; 

 even in the highest classes of animals the number of veg- 

 etable-eating species is immense ; and man, standing at 

 the head of the mighty chain of being, also derives most 

 of his food from the vegetable kingdom. 



Plants themselves, however, unlike animals, subsist 

 on barely inorganic matter; they do not, like them, 

 require a digestive apparatus by which the aliment neces- 

 sary to their existence is extracted from the rude mass, 

 but absorbs the nutritive portion through the roots. The 

 fluid, thtis introduced into the body of the plant, and 



