191S.] PUBLIC DOCUMENT — No. 31. 63a 



nite infection. This problem has a direct bearing upon the 

 routine work of testing breeding flocks for indications of 

 Bacterium yullorum infection. 



3. The Value of Anti-hog Cholera Serum in the Pre- 

 vention OF Hog Cholera. 

 The hog cholera investigations, carried on by the writer, are 

 being prosecuted according to the general plans outlined in an 

 earlier report. They have for their object the determination of 

 the value of anti-hog cholera serum in the production of immu- 

 nity for the prevention of hog cholera, the best methods of appli- 

 cation, and the development, potency and continuance of 

 inherited immunity. For use in these studies a herd of from 

 75 to 150 pigs is kept that is fed largely upon raw garbage 

 collected about the town. 



