246 DISEASES OF TREES 



carving of figures or letters. Should these be formed in the 

 cortex the wound will be of the same shape as the figure, 

 and the latter may be recognized for many decades, even 

 after callus has been formed, owing to the difference in the 

 appearance of the old and new cortex. If, on the other hand, 

 the cortex is first removed from a considerable surface of wood, 

 and the figures are carved in the wood itself, they disappear 

 when the wound closes. All that can afterwards be perceived 

 is the boundary between the old cortex and the place from which 

 the cortex had been removed.* 



When it is intended to remove a ring of dead bark from the 

 Scotch pine for the purpose of laying on a band of tar, the living 

 bast, and even the wood, are frequently unintentionally cut into 

 as well. Even after the tar has been laid on, turpentine and resin 

 continue to exude from the wound and form a white covering on 

 the black tar. This has given rise to the erroneous impression 

 that the tar partially dissolves the cortical tissues and causes 

 wounds in the bast. 



Precisely similar wounds result from the removal of bark from 

 old pines for the purpose of obtaining fuel for laundries, as 

 occasionally happens in the neighbourhood of towns. When 

 climbing irons are used for scaling trees wounds are also 

 extensively formed, and especially so during the harvesting 

 of cones, and the cutting down of spruce-branches for litter. 



WOUNDS DUE TO CRUSHING 



During the felling of timber in a close wood, it often happens 

 that a falling tree, or one of its branches, strikes an adjoining 

 tree, stripping off and crushing the cortex. During pruning the 

 top rung of the ladder crushes the cortex of the branch against 

 which it is laid. In dealing with insect ravages it was formerly 

 a common practice to shake the trees by beating them violently 

 with the back of an axe so as to frighten the caterpillars and 

 make them drop off. In consequence of crushing due to these 



* [Such cut letters, &c., are often found deep down in the wood many years 

 ater, the successive annual rings formed by the occluding callus having 

 covered them completely over. The burying of wire, nails, chains, &c., deep 

 n the wood is due to similar occlusion by a callus which gradually forms 

 wood over the edges of these objects. ED.] 



