INTRODUCTION xiii 



that sometimes destroys a hundred million dollars worth of 

 property in a year, it is not difficult to see the value of that 

 precise knowledge which is required to deal promptly and 

 efficiently with these plagues. 



It is a narrow and incorrect view to hold that the farmer 

 who owns these animals is the only one who suffers from the 

 ravages of the diseases which destroy them. Animal products 

 constitute a large part of the national food supply. If this food 

 supply is diminished, made dearer and more difficult to obtain, 

 want, misery, disease and death among mankind increase. At 

 first the effects of a scarcity of the food supply may be almost 

 inappreciable and felt only by the very poor ; but as the con- 

 ditions of famine are approached, suffering is multiplied and 

 intensified until whole communities are prostrated or destroyed. 

 Anabundantsupply of wholesome and nutritious food is, there- 

 fore, an essential condition of the welfare and prosperity of a 

 people. 



The great commercial operations of nations also depend to 

 a great extent upon the good condition of animals. When 

 all of the horses are disabled by an epizootic, as they have 

 been on rare occasions by influenza, the delivery of purchased 

 goods has nearly ceased, the shipments of flour, iron, machiner^- 

 and other products have been temporarily arrested and busi- 

 ness has been almost at a standstill. Again, it should be re- 

 membered that we export annually from the United States 

 forty million dollars worth of live animals, one hundred million 

 dollars worth of meats, fifty-five million dollars worth of lard, 

 tallow and other animal fats, and nine million dollars worth 

 of dairy products. lyet this traffic be stopped by a shortage 

 of supplies or b}- prohibitive orders of other nations on account 

 of the unrestrained prevalence of infectious diseases, and the 

 earnings of steamships, and rail-roads, and banks, and com- 

 mission houses, are at once diminished ; men employed in these 



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