ISO WILD NATURE IN STRATHEARN. 



tents, but eating voraciously at night till not a 

 particle of green is left ; so that if the tree does 

 not perish, it remains actionless for the year. 

 Nor is the mischief confined to the leaves, for 

 without their action the sap does not change 

 into a healthy cambium, fit for producing the 

 new layers of wood and bark, the constant 

 accompaniments of life and vigour. The whole 

 active surface of a back-going tree thus becomes 

 saccharine, and is infested with swarms of insects 

 of different kinds down to the very roots ; and 

 in the course of the summer the bole and branches 

 become full of canker ; half the top dies, branch 

 after branch, and the miserable remnant of the 

 once fruitful and ornamental tree becomes equally 

 unproductive and unsightly. When a tree is 

 thus attacked its recovery is always doubtful 

 and generally hopeless. Wood and bark that 

 have stood more than one winter are much less 

 fit for vegetable action, even though they have 

 received no direct injury, than when they have 

 only showed one. But in a tree which has 



