HARMONIES OF VEGEFATION. 259 



be formed of elementary gases and vapours, -which also assist either 

 directly or indirectly, in the support of vegetable life. 



15. That the food of plants is derived from these two 

 sources, no one can deny, not only because there is no 

 other medium to offer nutriment, but from the proof 

 which nature herself displays, by the luxuriance and 

 beauty of most plants in their natural soil and climate. 



What are the precise constituents of soil, &c. for every kind of 

 plant, can only be decided on by patient and accurate trials. 



NOURISHMENT OF PLANTS. 



16. The nourishment of plants must evidently be 

 secured to them by the process of absorption ; that of 

 non-elastic fluids by the root, and those of a gaseous 

 nature, principally by the epidermis. 



It is known, fruits will not ripen, and that roots do not thrive if 

 wholly deprived of air; and hence it is probable that they inhale it 

 by their epidermis, though the pores by which it enters should not 

 by visible. In the root, it may possibly enter into combination with 

 the moisture of the soil , but in other parts of the plant, it enters, 

 no doubt, in the state of gas. The leaves not only contain air, but 

 exhale it. 



17. The absorption of air and moisture by the leaves 

 and epidermis, gives us an opportunity to remark the 

 harmony which is displayed in consequence. 



The roots of all vegetables are furnished with innumerable small 

 fibres for the express purpose of deriving nonrishment irom the 

 earth. With herbaceous plants, the whole surface of the plant ab- 

 sorbs air and humidity by the pores of the epidermis. But with trees 

 and some shrubs, the case is somewhat different, the stems of which, 

 have such indurated crust, that no gas can penetrate them. A pro- 



