PRELIMINAKY STATEMENT. 13 



of the physiology and pathology of trees and arborescent 

 vegetation ; and most of what relates to the destruction of 

 forests through the carelessness of man may with advan- 

 tage be discussed apart under a discussion of the destruc- 

 tion of forests by fire and of preventive appliances. 



Mpst of the other measures specified will be discussed 

 in the sequel under the general head of Forest Economy, 

 inclusive of forest conservation and forest extension and 

 forest exploitation. But first must be established the 

 conviction of my readers that some such extensive destruc- 

 tion of forests as I have indicated has actually occurred, 

 with the results I have alleged. In view of this the 

 immediately succeeding chapters will be occupied with 

 illustrations of what has bfsen alleged, advanced in 

 illustration of the meaning of what has been said, but 

 which may be found to be to soihe extent of the nature 

 of proofs, — such proofs as hypotheses are subjected to by 

 experiments designed to test them by demonstrating their 

 accordance, or their want of accordance, with fact. 



