166 



Detail of Experiments 

 25 



appears important, and will lead me, further on, again to remark 

 upon this experiment. 



Fig. 25. exhibits an isolated branch, after the manner of 

 Pallisot de Beauvais, mentioned and figured by Sir Humphry 

 Davy ; with this difference, however, that, instead of an isolated 

 piece of bark only, it includes a branch of some size and age. 

 The space around the separated bark and branch was divested 

 of all the cortical layers and pulp, or cambium. The branch 

 continues as healthy and vigorous as any others on the tree, and 

 exhibits a beautiful example of the descending principle, both 

 from the edge of the bark above the separated part, and the edge 

 of the bark below the branch, on the separated bark ; the woody 

 layers formed beneath having been evidently produced through 

 the medium of the leaves of the branches, as the formation is 

 principally below the line of the brancKs insertion on the tree. 



Tig. 26. shows a tree so managed as to exhibit two surfaces 

 of the greater portion of the internal parts of the tree, without 

 apparently interfering with its growth above the operation. The 

 tree is thus placed on four separate pillars of bark and alburnous 

 wood. This has proved an exceedingly curious and interesting 

 experiment, and will, I hope, prepare the way for some experi- 



