

VEGETABLE PHYSIOLOGY. 13 



those clefts are continued, so that the whole tube, more or less, 

 is cut into a spiral line ; which, in some young branches and 

 tender leaves, will unroll to a great extent, when they are gently 

 torn asunder. The cellular texture especially is extended to 

 every part of the vegetable body, even into the thin skin, called 

 the epidermis, which covers every external part, and into the fine 

 hairs or down which, in some instances, clothe the cuticle itself. 

 Before we offer any thing upon the supposed functions of these 

 different organs, we shall take a general view of the vegetable 

 body, beginning with the root, the first organ to be described. 



CHAP. I. 



Anatomy of the Root. 



The root, which, though often differing in its bulk and shape, 

 is similar in all its structure and use, (with the exception of the 

 bulb, which, from containing the rudiments of a new individual, 

 may more properly be considered a variety of the seed,) is that 

 part of the vegetable which fixes the plant to the ground, is its 

 organ of nourishment, and the apparatus by which, through its 

 various ramifications, below the surface, it imbibes food from 

 the soil. 



In its structure, it is composed of the same parts as the stem 

 and branches, and therefore may only be considered as the stem 

 inverted ; the lower portion of the tube dipping into the earth, 

 and forming itself into minute ramifications without leaves ; and 

 the upper portion ascending, and producing buds, branches and 

 leaves. This has been illustrated by experiments made upon the 

 plum, cherry and willow, in which, by inverting the stem and 

 root, the former has become a root, sending out ramifications, 

 and the latter a stem producing leaves, flowers and fruit. The 

 structure of the root and stem is therefore one and the same 

 thing, and it is the situation in which each is placed, and the 

 operation of the surrounding medium, that makes the difference ; 

 giving to each, a variation in its chemical and medicinal properties 

 though their physical structure continue the same. 



