The Evolution of Bacteriology 27 



In 1894 Yersin and Kitasato independently isolated the 

 bacillus causing the bubonic plague then prevalent at 

 Hong-kong. 



A new era in bacteriology, and probably the most tri- 

 umphant achievement of scientific medicine, was inaugurated 

 when, in 1890, Behring explained to the world the principles 

 of the " blood-serum therapy," and since that time the 

 chief investigations have been along the lines of immunity, 

 immunization and the therapeutic serums, the names of 

 Behring, Kitasato, Wernicke, Roux, Bhrlich, Metschnikoff, 

 Bordet, Wassermann, Shiga, Madsen, and Arrhenius, taking 

 front rank. 



The most recent important discovery, that of the Tre- 

 ponema pallidum, the specific organism of syphilis, was 

 made in 1905 by Schaudinn and Hoffmann, long after clinical 

 study of the disease had anticipated it to such an extent 

 that when the discovery was finally made it was unnecessary 

 to modify our ideas of the disease in any essential. 



