INJURIOUS INFLUENCES 83 



great distance away are quite exempt. In 

 several stations in and around London trees 

 have frequently been injured, while in other 

 parts of the same grounds similar species have 

 remained for years untouched. Usually the 

 damage done to trees by lightning is trivial, 

 only a strip of bark some two or three inches 

 wide from the point where the fluid struck the 

 stem down to ground level being destroyed. 

 This injury, however, if not attended to in 

 the matter of pruning and dressing, may 

 have serious results. It is a simple matter to 

 assist nature in the healing process by careful 

 treatment in the way of pruning and applying 

 a coat of tar as soon as possible after the tree 

 has been injured. 



Constricted bark, occasioning a hidebound 

 condition of trees, is brought about either 

 through the roots becoming too feeble to carry 

 out their proper functions, or by exposing 

 hitherto-sheltered trees to cold winds. The 

 bark becomes hard or indurated, loses its elastic 

 properties, and the sap vessels get constricted 

 and their proper functions suspended. Under 

 these conditions the bark of the chestnut and 



