150 THE OAK. 



As we have seen, the forester has to exercise con- 

 siderable forethought the outcome of long experience 

 in growing oak so as to obtain long, clean stems. The 

 natural habit of the tree is to form a short, thick bole 

 and a widely spreading crown, the main branches of 

 which come off not far from the ground. To compel 

 the stem to elongate into a long pole he has to plant 

 other trees with it (as we have seen, beech, spruce, etc.), 

 which, while they keep the light off the lower parts of 

 the oaks, do not overtop them. This makes the trees 

 long and spindly at first, as they run up their leaf- 

 crowns higher and higher, and it is part of the forester's 

 art to select the exact time when he may cut away some 

 of the nurse trees and let in just enough, and not too 

 much, light and air, so that the crowns of the oaks shall 

 fill out more and thicken the stems. For it must never 

 be forgotten that the timber is laid on from substance 

 prepared in the leaves. 



The natural shape, so to put it, of an oak-tree is 

 that of a wide-spreading, short-stemmed mushroom, and 

 such a shape is realized in the open ; the forester com- 

 pels it to lengthen its stem as much as possible before 

 he lets it extend its crown. Hence he aims at length 

 first, and then lets the tree put on timber in the mass. 

 He does this, of course, by taking advantage of the tree's 

 peculiarities, and one of these is that it grows very 

 rapidly when young. It will be obvious that the skilled 

 forester also has to aim at getting as much timber as 

 possible on the ground in a given time, and in the case 



