FOREWORD 



It is with no ordinary feeling of pleasure that I have fallen 

 in with my friend Mr. Nowell's suggestion that I should write 

 a foreword to his book, although his own established reputation, 

 based on brilliant elucidations of various difficult problems in 

 plant pathology makes the attempt perhaps less easy and 

 certainly more superfluous than it might otherwise have been. 

 Readers will find in this book much more than is often regarded 

 as sufficient to fill a volume purporting to deal with plant diseases. 

 It might, indeed, perhaps be more correctly designated as a 

 treatise on the principles of plant pathology with special 

 reference to the diseases occurring in the West Indies. These 

 islands, with their wide range of soil, with their varied climatal 

 and other environmental conditions, are peculiarly well fitted 

 to provide that broad outlook over the larger matters of pathology 

 which is too apt to escape those who are treating plant diseases 

 from a more purely practical and local standpoint. Mr. Nowell 

 has embraced the opportunity which lay to his hand, and has 

 produced a work which in my judgment constitutes a real land- 

 mark of progress in the science of the plant considered in relation 

 to health and disease. As might have been expected from one 

 who has successfully grappled with the interesting and important 

 jetiology of Red Ring in Coconut, with the real nature of the 

 damage wrought by the Cotton Stainer (Dysdercus) and its 

 remarkable parallelism to malarial infection in the human 

 subject, to say nothing of his work on RoseUinia and other pests, 

 the book will be found of great value to the practical agriculturist 

 as well as to the scientific investigator, who looks, or should look, 

 farther afield. But it is in the philosophical treatment of his 

 subject as a whole, as well as in the cautious way in which the 

 principles themselves are put forward, that the wider interest of 

 the author's work as a whole is to be attributed. As is well said 

 in the text, " In every case of parasitism there are two organisms 

 to be considered, the host and the parasite. ..." In a number 

 of instances it is shown how the incidence of a particular disease 

 depends on external conditions, and the way is thus paved for a 

 rational treatment of an infestation which depends upon a 

 knowledge of what might be called the agricultural physiology 

 of the plant itself. If I may be permitted to recall something of 

 what I have myself observed, while in the West Indies, I might 

 cite the froghopper attack on sugar-cane as an instance of the 

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