GENERAL CONSIDERATIONS. 11 



de Courval has amply demonstrated by numerous 

 remarkable specimens exhibited at the Agricultural 

 Show of Paris, in 1861, and at the Universal Exposition 

 of London, in 1862, that it is beneficial, and often in- 

 dispensable, to prune the oldest trees if care and judg- 

 ment are used in the operation. He has clearly 

 shown, too, that trunks so treated attained a larger 

 size and a greater value in a given time than those 

 which, under similar conditions of growth, had been 

 allowed to retain all their badly placed branches. 

 I regret in this connection to differ from so eminent 

 an authority as de Breuil, who gives the following 

 rule : " Amputations must be performed in such a 

 manner that the diameter of the wound shall not 

 exceed that of the end of the branch." Such a 

 practice must, I believe, be dis- 

 astrous, for whenever a branch 

 of large size is amputated in this 

 way, it is evident that a cavity 

 in the trunk of the tree will 

 sooner or later appear. 



Disadvantages of the Common Sys- 

 tem of Pruning. As descending 

 sap alone forms the new bark and 

 wood which heal over a wound, it follows that, if 

 a cut is made in the manner represented by the 

 line A B (Fig. 5), the new growth cannot cover 

 over the lower part, B C, which is cut off from 

 communication with the leaves ; so that the wood 

 included in the lines A B, AC, not being covered 



