HOG-CHOLERA. 537 



blood of infected rabbits exposed to 58 C. This blood 

 was found to be exceedingly toxic. 



DeSchweinitz ' found that the introduction of progress- 

 ingly increased amounts of cultures into cows caused the 

 development in them of an antitoxic substance capable 

 of protecting guinea-pigs from the disease. 



After several years of treatment, some horses which I 

 attempted to immunize for antitoxin formation failed to 

 give serum powerful enough to be of use. To protect a 

 rabbit against fatal infection required several cubic centi- 

 meters of the blood. 



Working in my laboratory, Pitfield 2 has found that 

 after a single injection of a sterilized bouillon culture of 

 the bacillus into the horse, the serum, which has origin- 

 ally slight agglutinative reactive power, is so changed as 

 to show a decided reaction. If the horse be immunized 

 to large doses of such sterile cultures, the serum reaction 

 becomes so marked that with a dilution of 1 : 10,000 a 

 typical reaction occurs in sixty minutes. 



According to this experiment, in doubtful cases the 

 use of this reaction should greatly facilitate the differen- 

 tiation of the bacillus of hog-cholera from similar ba- 

 cilli. 



1 Cenlralbl. f. Bakt. u. Parasitenk., xx., p. 573. 



2 Microscopical Bulletin, 1897, p. 35. 



