xvi INTRODUCTION 



employed in these enterprises are discharged, and in innumer- 

 erable ways the welfare of people who have no part m the 

 ownership of any of these animals or their products is affected. 



Finally the most serious of all is the case in which the 

 animal plague, in addition to being destructive to animal life, 

 is communicable to and fatal to man, as is true of anthrax, 

 rabies and tuberculosis. Such diseases destroy property, dis- 

 turb business, lessen the food supply, and directly threaten 

 human life. What more is needed to impress upon the reader 

 the supreme importance of studying and understanding the in- 

 fectious diseases of animals ? 



The pathology of these diseases is in itself a large subject. 

 Investigations concerning it have extended over more than a 

 century of time and the literature of the subject is enormous. 

 To concentrate this knowledge, to select the truth and discard 

 the errors, and to develop a concise and systematic treatise is 

 a task of great magnitude and one which has required much 

 labor and thought. The writer has not seen the manuscript, 

 but, from his long and intimate acquaintance with the author, 

 he feels sure that the work has been patiently, carefully, intelli- 

 gently and thoroughly done, and that it will be favorably 

 received. 



D E. Salmon. 



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