PREVENTION OF WOUNDS 225 



to cut slits in the bark, so a slow-growing callus 

 can be relieved by slitting the bark of the callus. 

 There is this difference, however, that the bark 

 of the callus need not be bound, in order to profit 

 by the slitting. Even a rapidly growing callus 

 of one or two years can be made to grow even 

 more rapidly by cutting through its bark. In- 

 deed, I have sometimes cut a callus twice a year, 

 once in May and again in July, with obvious ad- 

 vantage. It is really surprising how rapidly a 

 wound will be healed over, if it is close to the trunk 

 of a healthy, growing tree, and the callus over it 

 has its back scratched occasionally with a sharp 

 knife. 



The method of operating is simply to draw the 

 point of a sharp knife around the callus, parallel 

 with its edges. The cuts can be made not only on 

 the inner face of the callus, near the wood over 

 which it is spreading, but also farther back. The 

 writer usually uses a number of short cuts rather 

 than entire circles. 



The best way to deal with the question of 

 wounds in trees, after all, is to prevent the trees 

 from being wounded. The great majority of 

 wounds are due purely to carelessness and igno- 

 rance. They can and should be prevented by in- 

 telligent pruning, and by protecting the trunks of 

 trees which are exposed to extraordinary dangers. 



If a tree is pruned rationally at not too great 



