58 ON VEGETABLE PHYSIOLOGY. 



lower portion of the tube dipping into the earth, 

 and forming itself into minute ramifications with- 

 out 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 stein and root, the former has become a root, 

 sending out ramifications, and the latter a stem 

 producing leaves, flowers and fruit. The struc- 

 ture 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 make the difference ; giving to each, 

 a variation in its chemical and medicinal properties 

 though their physical structure continue the same. 

 The main body of the root, which has been 

 termed the caudex, upon its first penetrating the 

 ground, possesses but very limited powers of af- 

 fording 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 undis- 

 covered process, those nutritive parts, which, 

 through the agency of water, become a fluid 

 termed the sap, and convey it to the caudex ; 

 from whence it rapidly ascends to the stem and 

 branches, and thence to the uttermost extremity 



