THE TREATMENT OF THE SHOOT i6i 



It is more advantageous to make only a very narrow circular 

 cut on very vigorous shoots, so that the wound may become 

 closed during one vegetative period. After the healing has 

 been effected the upper end of the shoot can continue its 

 growth in length, and the lower portion will again receive the 

 necessary material for the normal increase in thickness of the 

 wood and for the production of buds. This can be brought 

 about with certainty if the branch is constricted with a ring 

 of wire. The growth of wood at this point is in the first place 

 altered by the pressing together of the wood fibres, which be- 

 come laterally twisted. Very few true vessels are formed 

 between them. Afterwards, when the wire becomes enveloped 

 by the new growth, the cortex and bast are ruptured and a 

 soft wood is formed consisting of short, wide parenchymatous 

 cells. Of course, as long as the wire has not been grown over 

 the branch is liable to break off; but in other respects no 

 care need be taken for its further development. A deep black 

 discolouration of the wood will be noticed in the neighbour- 

 hood of the wire, but no attention need be paid to this appear- 

 ance. It is caused by the combination of tannic acid with the 

 iron and penetrates far into the wood. It is the layers of 

 splint-wood formed after the concrescence has taken place 

 which form the chief conducting tissue for the upper portion 

 of the branch. The sufficiency of the layers of splint- wood to 

 supply the entire leaf system is apparent from the vigorous 

 growth of hollow willows. 



(c.) Peeling the Stems. 



The most dangerous operation which is performed upon the 

 living tree, and which is a matter of life or death to the in- 

 dividual, is the process of peeling off the bark. In such cases 

 a large portion of the bark of a thick branch or stem, extend- 

 ing in length from six inches to three feet, is removed. It is 

 therefore a process of ringing on a large scale, and we only 

 adopt it as a last resource when all other methods of making 

 a tree productive have failed. 



The danger of this operation is the uncertainty of the heal- 



L 



