196 LOUIS PASTEUR 



of Pasteur, stating that he would submit his reply- 

 later in writing. When the reply appeared Koch 

 did not deny the principle of attenuation but spoke 

 of it as a most important discovery. Nevertheless 

 he expressed doubt of the practical benefits of vac- 

 cination for anthrax. In response, Pasteur sub- 

 mitted, among other evidences, data supplied by 

 the veterinary surgeon, Bontet, in regard to 79,392 

 vaccinated sheep, with a mortality of less than one 

 percent, whereas in the same district in the last 

 ten years the mortality had been more than nine 

 percent. Equally favorable results were reported 

 also for cattle. Time and fuller experience, how- 

 ever, have now settled all controversy over the 

 efficacy of inoculation for anthrax. 



Being pressed by some veterinarians to study the 

 disease known as swine plague or rouget, Pasteur 

 began by seeking to cultivate the microbe of this 

 disease. Thuillier, in 1882, had discovered numer- 

 ous very small bacteria in swine afflicted with 

 rouget, and Pasteur, who succeeded in cultivating 

 the germs in a suitable medium, found that these 

 cultures inoculated into healthy swine would set up 

 the disease. The next step was to develop an at- 

 tenuated virus. In experimenting on the behavior 

 of the disease in several small animals it was found 



