300 BACTERIOLOGY. 



a fanatical opponent of vaccination the things 

 he really accomplished were disregarded. His 

 work contained nevertheless a sound kernel 

 which, together with the facts previously dis- 

 covered by Jenner and Thiele, included many 

 things in the way of practical experiment and 

 simple observation of nature. Later all this 

 ground had to be experimentally won anew. 



Isopathic or Specific Inoculation With Living 

 Parasites Attenuation of Disease-producing 

 Bacteria. 



This new principle is connected with the 

 name of Pasteur, who in 1880 observed that 

 the parasites of chicken cholera, a malignant 

 disease of the domestic fowl, related to the 

 swine-pest, could by artificial treatment be 

 made to suffer such loss of virulence that the 

 animals inoculated became affected only locally 

 and did not experience a general and fatal in- 

 fection. The animals after being affected in 

 this way only at the place of inoculation could 

 subsequently be inoculated with the virulent 

 parasite without fatal results ; they were pro- 

 tected against the disease by the preliminary 

 inoculation with the weakened virus. In a 

 similar way, by attenuating various microbes, 

 such as the bacteria of anthrax, of symptomatic 

 anthrax and of swine erysipelas the attempt 



