258 MAINE STATE COLLEGE 



ciate the difficulties that have been encountered, enough has been 

 accomplished to amply compensate for all the trouble and expense. 

 Ten years ago the most confused ideas and conflicting opinions in 

 regard to the whole subject were held even by those best 

 informed ; to-day it can be safely said that while there is 

 doubtless much to learn, there is hardly a disease of any of our 

 domestic animals that is better understood than are the conta- 

 gious diseases of swine. 



The importance of investigating this subject is apparent when 

 we have to face an .annual loss in the United States alone of over 

 $15,000,000, leaving out of account the incidental losses due to 

 the decreased value of the faims and farm crops in localities 

 where the pork raising industry has been destroyed or seriously 

 injured. No section of the country has been spared, but the 

 loss in many sections has been about in proportion to the number 

 of hogs kept. The fatality has been so great in some sections 

 well adapted to the cheap production of pork that the business has 

 practically been given up. 



As near as can be learned from the imperfect records kept. Hog 

 Cholera was first brought to this country from Europe about fifty 

 years ago. At first gradually and later quite rapidly it spread 

 through the country until it has come to be quite a serious ques- 

 tion whether we will not have to give up the profitable production 

 of pork on a large scale on account of its ravages. 



Since 1879 the Bureau of Animal Industry has been giving par- 

 ticular attention to the disease of swine, endeavoring to gain such 

 information as would be of benefit to the pork raising industry. 



The Experiment Stations of the West and South have also done 

 much work in the same direction. 



When this work was commenced by the Bureau of Animal 

 Industry very confused ideas prevailed in regard to the whole 

 subject, and with the imperfect methods of investigation then 

 available little apparent advance was made. Investigators were 

 groping in the dark, endeavoring to discover the real cause of 

 the diseases, hoping that with a knowledge of the cause a remedy 

 Could be found. In 1885, with the improved methods for bacte- 

 rialogical investigation perfected by Prof. Koch, of Berlin, Dr. 

 Salmon, Chief of the United States Bureau of Animal ludustry, 

 discovered in cases of Hog Cholera that he investigated a bacillus 

 which he calls the Hog Cholera Bacillus. Subsequent experi- 

 ments and investigations by Dr. Salmon resulted in the discovery 



