68 



SYLVA AMERTCANA. 



body is necessary for the life and increase of another. All 

 nature is in motion. In consequence of the putrid fermentation 

 that is every where carried on, a quantity of vegetable nutriment 

 ascends into the atmosphere. Summer showers return much of 

 it again ; but part falls into the sea and is lost. To this we may 

 add the animal and vegetable substances consumed on board of 

 ships, all of which are buried in the ocean. The industry of 

 man restores them to the earth ; and we may presume that the 

 fish taken from the sea leave a balance in favor of mankind. 

 Thus Providence, with the most consummate wisdom, keeps up 

 the necessary rotation of things. Hitherto I have considered 

 plants as nourished by their roots ; I shall now take a view of 

 them as nourished by their leaves. An attention to this part of 

 the vegetable system is essentially necessary to the rational 

 farmer. Vegetables that have a succulent leaf, such as vetches, 

 peas, beans and buck wheat, draw a great part of their nourish- 

 ment from the air, and on that account impoverish the soil less 

 than wheat, oats, barley or rye, the leaves of which are of a firmer 

 texture. Rape and hemp are oil-bearing plants, and consequently 

 impoverishers of the soil ; but the former less so than the latter, 

 owing to the greater succulency of the leaf. The leaves of all 

 kinds of grain are succulent for a time, during which period the 

 plant takes little from the earth ; but as soon as the ear begins to 

 be formed, they lose their softness and diminish in their attractive 

 power. The radical fibres are then more vigorously employed 

 in extracting the oily particles of the earth for the nourishment 

 of the seed. Such, I apprehend is the course of nature. 



" The air contains, especially during the summer months, all 

 the principles of vegetation ; oil, composed of gasses, vegetable 

 extracts, earths, manures, &c. for the perfect food, water to 

 dilute it and salts to assimilate it. These are greedily absorbed 

 by the vessels of the leaves and bark, and conveyed to the 

 innermost parts of the plant for its growth and fructification. 



" In order that we may have a distinct view of the motion of 

 the sap, it will be necessary to reflect, that the root, stem, 

 branches and leaves are constructed in the same manner. 

 Sallows, willows, vines and most shrubs will grow in an inverted 



