Creeh System of Pruning Forest Trees. 437 



the stem, shooting forth buds and expanding leaves. The com- 

 mon sap, having extended over all the branches, mingles with 

 the fluid absorbed by the leaves, and, losing the watery and 

 aeriform principles, which are useless for nutrition, by evapo- 

 ration, it returns down the vessels of the bark, and in its course 

 deposits cambium, which forms the annual rings of wood, then 

 extends to and strengthens the extremities of the rootlets, 

 whereby they are made to extract more nourishment from the 

 soil throughout the season, and, as the two saps commingle in 

 the leaves, the descending sap, which has not been deposited, in 

 like manner mixes with that extracted by the rootlets, and is 

 again carried up with the ascending sap. 



How to economise these fluids for the advantage of the tree is 

 next to be considered. It is obvious, then, that when the upper 

 lateral branches are shortened to half the length of the leading; 

 stem, and the others proportionally, the sap has less superficies 

 to cover than when they are allowed to extend to an improper 

 length and thickness ; in consequence, there is a greater supply 

 for every part of the tree ; and as other fluids, such as water, 

 moving in a channel, acquire additional momentum when 

 augmented, greater vigour and velocity of movement are im- 

 parted to the sap by the abundance of quantity ; and so great is 

 the beneficial effect resulting therefrom to the tree, that, from 

 the extraordinary size and health of the foliage which clothes 

 the branches, it attracts more than three times the nourish- 

 ment ordinarily imbibed from the atmosphere under different 

 management. 



The branches which are shortened always remain slender. By 

 reason of the small superficies of the branch, and the rapidity with 

 which the sap moves, very little of it is retained by the branch, 

 and of course nearly the whole is deposited in the body of the tree. 

 This truth, with the fact that the foliage remains nearly a month 

 longer on the trees so shortened than on others, accounts for 

 the wonderful rapidity of growth effected by this method of 

 pruning. The smallness of the brandies is of advantage likewise 

 when it is necessary to prune close to the stem, as the wound 

 made by that operation is proportionally small, and may be 

 expected to cicatrise in the course of three years. 



It may be worth remarking, that, if the branches are pro- 

 perly shortened, trees never become what is termed hidebound. 

 In the royal forests. Lord Glenbervie had instruments for 

 ripping the bark of oaks (which never could increase nutrition), 

 and scraping off' the lichens ; but had the branches been judi- 

 ciously shortened, the descending sap would have been so aug- 

 mented, through means of a more healthy foliage, as to have 

 obviated the disease ; as the bark expands in proportion to the 

 quantity and quality of sap carried down, and if that be abundant, 



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