vi PREFACE TO THE ENGLISH EDITION 



than his admirable discussion of the complex phenomenon of 

 "Leaf-casting" on pp. 110-117 of the present work ; while his 

 work on the Zersetzungserscheinungen des Holzes is a model of 

 thoroughness and scientific accuracy and acumen to which all 

 workers in this branch of botany must look up. 



In this country we are awakening rapidly to the necessity 

 of placing ourselves abreast of the new ideas involved in this 

 compound study of plant-pathology ; but we are perhaps as yet 

 by no means so alive to the practical importance of the new 

 discipline as it might have been inferred (from our national 

 pride in being practical) we should be. 



Animal-pathology is studied with zealous and expensive 

 enthusiasm I suppose because, being animals, we are at once 

 alive to its importance ; but plant-pathology, in the real sense 

 of the term, scarcely obtains recognition as yet, no doubt owing 

 to our interest in the culture of trees and agricultural produce 

 having seemed to be less pressing than coming events are likely 

 to prove it really to be. ' From this condition only apparently 

 apathy we are doubtless awakening, and, as is usual, when we 

 English do awake to new necessities, we at once enthusiastically 

 set to work to recover lost ground. 



Now, in this department, we have to awaken to some startling 

 new facts, the practical bearings of which have deeply impressed 

 our Continental cousins for some years past. 



One of these new facts is that we may know a very great 

 deal about the systematic position and the morphology of 

 parasitic and destructive fungi without knowing much or, 

 indeed, necessarily anything about the diseases and injuries 

 they induce ; another of these new facts is that pathology 

 i.e. the study of disease cannot be fruitful unless the student 

 is experimentally acquainted with plant-physiology, and espe- 

 cially (though by no means only) the physiology of nutrition. 



To these statements I would add that we have, as a nation, 

 to force ourselves even more than we have yet done out of 

 the groove in which plant-physiology is looked upon as a mere 

 branch of chemistry and physics. It is no undervaluing of 



