DESCENT OP THE CAMBIUM. 79 



The practice which was adopted by Mr. Knight for 

 the illustration of vegetable physics, has been pursued 

 both in Europe and in this country for a very different 

 object. If a ring of bark is detached in the spring from 

 the trunk of the Olive, the quantity of its fruit is very 

 considerably increased. If a branch of the Vine 

 is treated in a similar way, it has been ascertained that 

 its fruit arrives at maturity, three or four weeks earlier 

 than usual. By adopting this plan, those tender Grapes 

 which could not otherwise be cultivated with success 

 at Paris, have been brought to perfection.* The 

 practice has also been adopted in this country, and it is 

 not uncommon to see Apple and other fruit trees, with 

 a portion of their bark detached. It has indeed super- 

 ceded the old rude practices, of filling their trunks 

 with nails, and boring to their pith, in order to increase 

 the quantity of their blossoms and fruit. 



The observations of Mr. Knight teach us in what 

 way the removal of a small portion of bark, may add to 

 the fertility of the fruit tree. By intercepting the de- 

 scent of the Cambium, a larger supply of food is collect- 

 ed in the extreme branches, and thus the fertility of 

 the tree, and the luxuriance of its young branches, 

 are at once promoted. And the same observations 

 teach us, that whatever impedes the descent of the 

 Cambium, will sooner or later interrupt the progress 

 of vegetation, for the root being deprived of its custom- 

 ary nourishment, loses its vigour and ceases to abstract 

 from the earth, an adequate supply of those materials, 

 by which old organs are nourished, and new ones are 

 formed. They also teach us that the fluids of a leaflet 



* Desfontaine's Arbres, &c 



