260 THE PROTECTION OF WOODLANDS. 



chloric acids), while Conifer-leaves turn yellow or red at the 

 tip before the whole needle is poisoned, discoloured, and killed. 

 And usually, too, in smoky localities Pine pole-woods are very 

 liable to attack by the leaf -shedding fungus, Lophodermium 

 pinastri. Under the Alkali Acts steps may be taken to pre- 

 vent hydrochloric acid issuing in injurious quantities from 

 works ; but the only practical remedies in woodlands exposed 

 to atmospheric impurities of any sort are to try and grow 

 broad-leaved crops, to maintain thick shelter-belts of hardy 

 trees on the side from which smoke comes, and to make oc- 

 casional falls, annually or periodically, rather than clear falls 

 and replantation. But where woods or plantations have been 

 destroyed by atmospheric impurities, the sowing or planting 

 of smoke- or gas-poisoned blanks is useless. 



