ON THE ORIGIN AND FORMATION OF ROOTS. IgJ 



can be changed into buds, or buds into roots ; but I had be- sap carri'-d up- 

 fore proved, that the oro-anization of the alburnum is better ^Vu ^ '^^ 

 r ' " _ alburnum, 



calculated to carry the sap it contains from the root upwards, 

 than in any other direction ; and I concluded, that the sap, 

 when arrived at the top of thecutlinff throu<^h the alburnum, 

 would be there employed, as I had observed in man*'^ similar 

 cases, in ajenerating buds, and that these buds would be pro- 

 truded where the bark was ycmn" and thin, and consequently 

 afforded little resistance*. I had also proved the bark to roots from, the 



be better calculated to carry the sap towards the roots than '""J^f "^ y'^'^' 



... ' . ward by tue 



in the opposite direction, and 1 thence inferred, that as soon bark. 



as any buds, emitted by the cuttings, afforded leaves, the 



eap would be conveyed from these to the lower extremity of 



the cuttings by the cortical vessels, and be there employed 



in the form.itioa of roots. 



Both the alburnum and bark of trees evidently contain The sameflnid 



their true sup ; but whether the fluid, which ascends in such |"''|^'''''' ^*'-"'* 



1 1- 1 both root and 



cases as the precedmg through the alburnum to generate buu. 



buds, be essentially different from that which descends down 

 the bark to generate roots, it is perhaps impossible to (de- 

 cide. As nature, however, appears in the vegetable world 

 to operate by the simplest means ; and as the vegetable sap, 

 like the animal blood, is probably tilled with particles vvhicti 

 jire' endued with life; were I to offer a conjecture, I am 

 much move disposed to believe, that the same Huul, even by 

 merely acquiring different motions, may generate different 

 organs, tiian that two distinct fluids are employed to form 

 the root, and the bud and leaf. 



When alburnum is formed in the root, this organ possesses Roots in w'Mch 



jn common with the stem and branches, the power of pro- *^^''*' '" ^,'!""; 

 . . ' ^ nunica i,\b!eof 



ducing buds, and of emitting fibrous roots; and when it is p...duung 



detached from the tree, the buds always spring near its up- ^^^^' 



per end, and the roots near the opposite extremity, as in the 



cuttings abovementioned. The alburnum of the root is 



also similar to that of other parts of the tree, except that it 



is more porou>, probably owing to the presence of abundant 



moisture during the period in which it is depositedf. And 



♦ Phil. Trans, for 1805; Journyl, voL XHI, p. 549. 

 t Phil. Trans, for 1801. 



possibly 



