PHYSIOLOGY OF TRKES. 261 



and there plunging* into the liquefied sap, descend 

 in close array, anastomozing as they proceed with 

 the medullary rays which cross their path, and 

 together furnish the fibrous matter of the swell- 

 ing cambium. This, it is said, shews how readily 

 rootlets are produced from cuttings — how inocu- 

 lated buds or grafts fix themselves to the stock ; 

 that it is not the matured sap which descends' 

 but the radical vessels themselves, and they it is 

 that carries with them the colours and forms of 

 the parents whence they have descended. It 

 accounts for the appearances observed on stran- 

 gulated branches, and particularly for the upper 

 sides of wounds closing faster than the lower. 

 It also accounts for the production of shoots from 

 the trunks of trees which have been long felled* 

 In short, there is hardly a circumstance in the 

 ordinary phenomena of vegetation which may 

 not be satisfactorily explained by the application 

 of this hypothesis. 



Notwithstanding the feasibility of this notion, 

 however, it is liable to one or two objections, 

 which fall to be noticed. It should be remem- 



