ii. ANTITOXINS 



Historical. The researches of Buchner 1 in 1889 

 had shown that the serum of animals artificially 

 immunized against a certain bacterium possessed 

 marked bactericidal properties for that particular 

 organism. In studying immunity on animals which 

 had been successfully immunized against diphtheria 

 infection, Behring, 2 working in Koch's laboratory 

 was struck by the fact that in these animals 

 living virulent diphtheria bacilli were often demon- 

 strable in the scab at the site of injection several 

 weeks after the infection, and furthermore that the 

 blood serum of these animals did not possess bacteri- 

 cidal properties as did the blood of animals immu- 

 nized against bacteria other than the diphtheria 

 bacillus. This fact and others which follow indi- 

 cated that the diphtheria bacillus differed from the 

 bacteria studied up to this time in its effect on the 

 serum of infected animals. In a study published 



1 Buchner, Centralblatt Bacteriologie, Vol. v, 1889. Archiv. 

 f. Hygiene, Vol. x, 1890. 



2 Behring & Kitasato, Deutsche med. Wochenschrift, No. 49, 

 1890. 



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