30 Bark Diseases. 



top," and I have, therefore, laid some stress 

 upon it. It is avoidable, but not curable. 



BARK DISEASES. 



Diseases of the bark may arise from 

 manifold causes, from the growth of epicormic 

 branches, induced by injudicious thinning, 

 wounds, ivy, wet and cold sub-soil, frost, and 

 insect attack ; the result may be excrescences, 

 a bark-bound condition, the separation of the 

 bark from the wood, and various other mani- 

 festations. From whatever cause it arises, 

 the " cambium," or formative fluid, which 

 flows between the inner bark and "alburnum," 

 or sap-wood, is retarded and does not reach 

 the leaves in sufficient quantities, and, 

 therefore, is insufficiently elaborated. This 

 engenders disease, which, if allowed to go on 

 unchecked, will end in the destruction of the 

 tree. 



The epicormic branches, that is the branches 

 growing from the stem, increase the tendency 

 to disease, through the interception of the 

 sap as it passes, thereby reducing the quantity 

 which is required to reach the leaf surface. 



