14 SYLVA AMERICANA. 



The main body of the root, which has been termed the caudex, 

 upon its first penetrating the ground, possesses but very limited 

 powers of affording nourishment; and it is not until it has sent 

 forth its ramifications or radiculce, and these ramifications have 

 issued still finer filaments of capillary diameter, that an extensive 

 absorption can be effected. These minute tubes, by dipping 

 into the soil in the direction where there is the least opposition, 

 abstract from it, by some undiscovered process, those nutritive 

 parts, which, through the agency of water, become sap, and 

 convey it to the caudex, from whence it rapidly ascends to the 

 stem and branches, and thence to the uttermost extremity of the 

 leaves, there to undergo a new modification to be hereafter 

 explained. The root therefore may be considered as acting the 

 same part towards the vegetable, as the stomach does to the 

 animal ; though the apparatus and the fluid prepared, bear but 

 little similarity. 



Of the Trunk or Stem. 



In cutting the trunk of a tree from the circumference to the 

 centre, the instrument passes through seven distinct parts, in the 

 following order : 



1. The epidermis, which extends over the surface of every 

 vegetable, as before described. It is also called cuticle, false 

 skin and the like, names which anatomists have given to the 

 external covering of animals. There is a striking analogy 

 between the animal and vegetable cuticle or skin. In the former 

 it varies in thickness from the delicate film which covers the eye, 

 to the hard skin of the hand or foot, the coarser covering of 

 the ox, or the hard shell of the tortoise. In the latter it is 

 exquisitively delicate, as in the covering of a rose leaf, and hard 

 and coarse in the rugged coats of the elm and oak. In the 

 birch, you may see the cuticle peeling off in circular pieces. 

 The vital principle seems wanting in it; this is the only part of a 

 living plant which is dead. In the larger trees and shrubs, the 

 bodies of which, in themselves, are strong and of firm texture, the 

 latter property is not of so much importance ; but in the reeds, 



