BUREAU OF AXIMAL IjSTDUSTEY. 145 



apjDears to be relative and not absolute, and frequently incapable of 

 j)rotectinfr subjects against excessive exposure to infection. 



Under experimental conditions localization of the infection in the 

 udders of milkino- cows has in rare instances appeared to follow the 

 administration of the treatment, a feature which has caused some 

 doubt as to the advisability of treating subjects other than unbred 

 heifers. The objett of vaticination has been regarded as being de- 

 feated when udder infection is occasioned, as much uncertainty then 

 exists as to the outcome of every pregnancy so long as the condition 

 persists. Further work directed toward acquiring more information 

 relative to this feature has indicated thut udder infection resulting 

 from subcutaneous injections of vaccine may possibly not occur with 

 sufficient frequency to render the procedure highly objectionable. 



Living-abortion organism vaccine has given indication up to the 

 present time of being merely preventive in action. Animals in which 

 Bacterium abortus infection is present at time of treatment are con- 

 sidered as deriving little or no benefit. It has, moreover, seemed 

 reasonable to assume that vaccination constitutes an illogical pro- 

 cedure in connection wdth animals which have previously acquired 

 the disease but no longer harbor the infection in their bodies. Their 

 resistance to reinfection is probably greatly in excess of the degree 

 than can be imparted to susceptible subjects by the treatment. 



Routine work, as usual, has demanded considerable attention. 

 More than 2,000 samples of blood serum were subjected to the aggluti- 

 nation test. The results obtained have frequently enabled cattle 

 owners promptly to take appropriate control measures. Correspond- 

 ence has furnished a means of disseminating information regarding 

 control measures to those who have manifested interest in the subject. 



BOTULISM. 



The active immunization of mules against botulism by means of 

 toxin-antitoxin mixtures was successfully accomplished. Two mules 

 were given at four-day intervals three subcutaneous injections of 

 toxin-antitoxin mixtures in which there was a slight excess of toxin. 

 The animals bore this treatment well, manifesting only a slight re- 

 action. Nineteen days after the last injection one of the mules was 

 injected with 6,000 guinea-pig minimum lethal doses of botulism 

 toxin, and three months after the last injection of the toxin-antitoxin 

 mixtures the second mule was likewise injected with 1.500 guinea-pig 

 lethal doses of the toxin. No symptoms resulted in either case. 



Some tests on guinea pigs showed that the passive immunity 

 afforded b}: injections of large doses of botulinus antitoxin does not 

 exceed three weeks. 



SWINE ERYSIPELAS. 



The occurrence of swine erysipelas in the United States is now 

 definitely established. During the early spring of the present year 

 observations were made on an outbreak of a fatal disease in suckling 

 pigs. Bacteriological study of one of the dead animals showed the 

 presence of Bacillus erysifelatis suis in practically pure culture in 

 the blood and various organs of the body. The organism in this case 

 proved to be identical in morphological, cultural, and pathogenic 



