72 



ligneous fibres, are some vessels which are not so nar- 

 row, composed of a silvery elastic blade, formed spire- 

 wise, like a spring : these are arteries ; they seldom 

 contain any thing but air. 



These four orders of vessels, which are dispersed 

 through all the parts of the vegetable, in proportion to 

 the functions of each, compose, at least in trees and 

 shrubs, three principal beds, the lark, the wood, and 

 the pith. 



The bark, or rind, which is the outer covering of 

 plants, and is smooth, even, and shining in some, and 

 rough, channelled, and hairy in others, is formed of the 

 widest fibres, that are the least pressed together, and 

 which admit within them the most air. 



The wood, which is placed under the rind, has nar- 

 rower and more contracted pipes, its utricles less re- 

 plenished or dilated ; and this only has arteries. , 



The pith, which is situated at the heart of thfe plant, 

 is little more than a collection of utricles, which are 

 greater and more capacious than those of the bark 

 and wood : they diminish and dry up as the plant ad- 

 vances in age. 



The simplicity of the organization of vegetables 

 is the principal source of their different methods of mul- 

 tiplication. 



A plant pushes out buds from all points of ks sur- 

 face ; these buds themselves are plants ; being cut and 

 laid in the ground they take root there, and become en- 

 tire plants, like that of which they were before only 

 a part. 



The smallest branch or leaf may give birth to such a 

 whole plant. 



Suckers taken from different plants, and ingrafted in 

 the stalk or branches of another plant, incorporate them 



