Sivine Growers' Session. 



Ill 



these lots from lot 4 by the attendant, who, in feeding and caring 

 for these pigs passed from pen to pen without any disinfection of 

 his shoes. This was done intentionally (after the outbreak of the 

 disease in lot 4) as it was evident that the opportunity for infect- 

 ing the "check" pigs in lots 1 and 2, in other ways, from lot 4 

 would throw doubt on any conclusion that these "check" pigs con- 

 tracted the disease from the vaccinated pigs of their own lot, 

 should the latter remain healthy. In this way a greater exposure 

 of all the vaccinated pigs was made than was at first planned. 



We may also regard the sick pigs of lot 4 as "checks" on the 

 value of the serum used in lots 1, 2 and 3, since the source of the 



Fig. 5. Hog cholera ulcers— Intestines— Vet. Dept, Mo. Experiment Station. 



infection in lot 4 was from the diseased blood used in the other lots. 

 I am confident that all of the pigs in these several lots had far 

 greater opportunities for contracting the disease than ever occurs 

 in a natural outbreak of cholera. 



We had an opportunity of still further testing the value of the 

 "hyperimmunized" serum in an outbreak of cholera in the State 

 farm herd, into which the disease had been introduced by some 

 hogs of the "show herd" which had returned recently from the 



