HISTORY AND ECONOMIC IMPORTANCE 6 



thousand hogs has been approximately 66. In 

 1897, the loss per thousand ran as high as 130. 

 Since 1914, the losses due to the disease have been 

 gradually diminishing, and it is believed that more 

 effective sanitary measures and more extensive 

 and judicious use of protective serum have been 

 responsible for this decline. 



Naturally a disease of such great economic im- 

 portance has been the object of close and pro- 

 longed study. In 1875, Dr. James Law furnished 

 the United States Department of Agriculture with 

 a report setting forth accurately the symptoms 

 and lesions of the disease, and speaking for its 

 transmissibility. Three years later, as a member 

 of a commission of nine men appointed by the De- 

 partment to investigate the disease, he succeeded 

 in transmitting it by inoculation experiments. Dr. 

 Detmers, acting as a member of the same commis- 

 sion, isolated an organism which he regarded as 

 its cause, but his findings were not confirmed. 



In 1885, Dr. Daniel Elmer Salmon and Dr. Theo- 

 bald Smith isolated an organism, now known as B. 

 suipestifer, which they believed to be the true 

 cause of hog cholera. Their work was confirmed 

 by trained investigators in this country and Eu- 

 rope, but all attempts to produce immunity to 

 field outbreaks by using B. suipestifer as an im- 

 munizing agent ended in failure. Thus during 

 the late nineties considerable doubt had developed 



