SECT. HI. CIRCULATION OF JUICES. 



it is again returned to the root were denominated 

 veins. 



Such was the original theory of the circulation of 

 the vegetable fluids, which was soon found to rest 

 on a very slender basis, and to stand in need of the 

 support and sanction of some substantial argument. 

 Accordingly the best arguments that could be ob- 

 tained were mustered up in defence of the doctrine. 



In proof of the digestive power of the root it 

 was said that if a tree is cut down level with the 

 earth, it will still continue to live and to send out 

 new shoots ; which it could scarcely be thought 

 capable of doing, except upon the supposition that 

 the sap is elaborated in the root, and not in the 

 upper part of the plant. But the Fir-tree uni- 

 formly dies under this operation; and although 

 most trees do indeed survive it, yet it is only by 

 virtue of new buds which are formed on the upper 

 part of the root, or remaining part of the stem, 

 and in which the process of elaboration is con- 

 tinued. For if you constantly destroy the buds as 

 they make their appearance the root will to a cer- 

 tainty die. It was urged, however, that the root 

 is the organ of elaboration, because, in plants having 

 a conspicuous proper juice, it may be readily per- 

 ceived by means of a transverse section oozing 

 from the very extremity of the root. But so also 

 it may be observed to ooze even from the extremity 

 of the stem. The argument then proves nothing ; 



