vi PREFACE. 



and what I am to do to set things right." Just so. 

 With the latter part of this cry one must sympa- 

 thize, much as a doctor does with the wail of the 

 parent who calls him in to cure his sick child 

 we need not stop to classify or compare the 

 motives of the parent and the cultivator, and 

 perhaps I had done better to select a breeder 

 of sheep with his flock and a veterinary doctor 

 in the illustration, but we will let it pass ; and 

 as regards the former part of the cry, I do not 

 know that the plant-doctor can expect the cul- 

 tivator to be initiated in the aetiology of the 

 disease any more than the physician expects the 

 parent to understand the biology of the typhoid 

 bacillus. That both the cultivator and the 

 parent would be the better for a real knowlege 

 of the disease in either case must be admitted 

 nay insisted on, provided the knowledge is real 

 but we have to deal with facts, and it is a fact 

 that the clients of both doctors are impatient of the 

 details of the case. 



Now, of course, I am aware that no short cut 

 or " royal road " to science exists, and if a man is 

 going to train up trees or other plants, he ought 

 to know all about them in health and in sickness, 

 in youth and in old age, and he ought to learn 

 everything about the soil they grow in, the air 

 that surrounds them, the enemies that beset them, 

 and all the multifarious relations of these one to 

 another ; but when I look at my boy and reflect 

 how much his nurse, his schoolmaster, his tutor, 

 his doctor, and his parents ought to know succes- 



