8o TREE WOUNDS AND DISEASES 



in their vicinity. Two instances of such have 

 been brought to our notice of late in the 

 Metropolis, in both of which trees that a 

 few years ago were sound and healthy have 

 been killed by being subjected to the emanations 

 from recently constructed smoke-shafts in the 

 neighbourhood. In one case fully twenty trees, 

 principally elm and horse-chestnut, gradually 

 showed signs of distress in the scantily produced 

 yellowish foliage, followed a year afterwards 

 by many dead and dying branches ; and in the 

 third season the trees had become so unhealthy 

 and disfigured that their removal was impera- 

 tive. In another instance with which we had 

 directly to deal, some healthy, rapid-growing 

 elms and catalpas were killed by the smoke 

 from an electric shaft. Probably, however, 

 the most deadly fumes to plant life in London 

 are those given off from the gold-refining 

 works at the Royal Mint. 



When trees have become unhealthy owing 

 to adverse atmospheric conditions, it is sur- 

 prising how quickly they become tenanted 

 with injurious insect life. The elm is soon 

 attacked by the bark beetle and goat moth, 



