INTRODUCTION 3 



subject of plant diseases is concerned, are unfortunately 

 to a great extent true at the present day : — 



' Every day's experience shows the wisdom of encouraging 

 amongst gardeners a higher order of education. It is not 

 enough for the present state of cultivation, or the require- 

 ments of intelligent masters, that they should be content 

 to follow in their predecessors' steps without attempting 

 anything beyond the usual routine, and taking advantage 

 of local circumstances either for the prevention of evil or 

 material improvements. Under a narrow system of educa- 

 tion and a low standard of qualifications, it may be well 

 to fall in with the common saw, " But he is a safe man and 

 will make no experiments," but a sound stock of principles 

 will at once dissuade from all unsafe experiments, and give 

 the power of meeting difficulties which to others would be 

 insurmountable' (Berkeley, Ga?'d. C/uvn., Nov. 27, 1847). 



The rule-of-thumb method of doing anything is pure 

 mimicry, that is, imitating more or less exactly, depending 

 on the amount of mimicry possessed by the operator, the 

 actions of some one else, without knowing or caring for 

 the reason why. Too much of this checks progress ; the 

 usual reply, that our forefathers succeeded without learning 

 all that is by some considered essential to success at the 

 present day, is not sound argument. 



' Knowledge is power,' and the man who possesses the 

 greatest range of knowledge relating to his special subject 

 is the one most likely to succeed. Hence it follows that 

 a knowledge of the broad principles regulating the mode 

 of life of those groups of parasites which prove so injurious 

 to cultivated plants should be clearly grasped ; and as the 

 fungi are most numerous, they will be dealt with first. 



