38 
FRUITFULNESS AND BARRENNESS OF PLANTS, 
5th. Carbonaceous matter, when dissolved in water, combines with 
oxygen and hydrogen in different proportions ; whenever oxygen pre¬ 
ponderates in these compounds of > carbonaceous matter and water, 
fructification is promoted and sustained; whenever hydrogen prepon¬ 
derates, plants grow more to leaf and stalk and branches, than to 
flow r ers, seeds, and fruit. 
6th. The food of plants is taken up by the roots in a state of fluid, 
impelled upwards through the stem, branches, and leaves, &c., and 
diffused through the system; each part of the plant having the power 
of selecting and appropriating the portion adapted to its use; the 
residue, or that which is excrementitious, is thrown off by the leaves. 
7th. The roots of plants are gradually propelled and extended into 
the earth, and there they continue to collect, absorb, and dispense an 
increased quantity of food, so long as it is supplied, and they grow 
unobstructed. 
8th. The quantity and quality of the food supplied to plants, af¬ 
fect them much in the same manner as it does animals; that is to 
say, with a scanty supply of food they grow but little, and with a 
superabundant supply of food, they grow to the utmost extent of leaf, 
trunk, and branches. 
9th. The leaves form the excretory organs of the plant or tree; 
and whether the supply of food be great or small, a plant or tree can¬ 
not attain or sustain itself in a perfect state of fructification, until it 
is furnished with a surface of leaves duly proportioned to the sap 
supplied by the roots. To enable them to perform their functions, 
also, it is necessary that the leaves should be duly exposed to the ac¬ 
tion of light, and to the influence of the sun and the air. 
10th. In all erect-growing trees and plants in an open situation, 
and where the light falls equally, the sap is impelled in a vertical 
direction, or the inverse of the natural flow of water ; that is, as wa¬ 
ter always flows in the greatest force through the lowest opening in 
a vessel or channel, the sap will flow in the greatest quantity into 
and through the highest opening, or that which is offered by the 
most vertical buds that are nearest the root. Anff the strongest and 
leading branches will grow in an upright perpendicular direction ; 
but in places where the light has a partial access only, the sap will 
flow, and the branches bend, towards that side where the light is ad¬ 
mitted. In creeping and climbing plants, the sap flows to the extre¬ 
mity of the branches, whether their position be horizontal or per¬ 
pendicular, and whether such branches be long or short. 
11th. The destruction or loss of any part of the buds, or young 
branches of a tree, will not prevent the growth and extension of the 
