103 



first, 23 the second, 13 the third, 3 the fourth, and i the 

 fifth and sixth inoculation. Koch reminds Pasteur, there- 

 fore, that even though an animal survive a virulent in- 

 oculation he is not thereby secure against subsequent 

 infection with anthrax. Further, Koch calls attention to 

 the fact proven by himself and others that immunity 

 against subcutaneous inoculation is not necessarily syn- 

 onymous with immunity against infection through mucous 

 membranes, especially of the alimentary canal ; although 

 Koch admits that as the fact had been proven only for 

 horses, dogs, mice, rats, and rabbits, it might be other- 

 wise with regard to sheep, with which he had not at that 

 time experimented. 



Such were the considerations advanced on either side. 



Pasteur's theory was soon extensively tested in Prus- 

 sia and Hungary the experiment was superintended by 

 an official commission of medical officers of the govern- 

 ment. The .proceeding has been usually the same. Pas- 

 teur vaccinates first with a weak virus, two weeks later 

 with a stronger one, and after two further weeks, the 

 animal is considered protected ; and those thus protected, 

 as well as others not vaccinated, are inoculated with ma- 

 terial fresh from an animal dead of anthrax. At the end 

 of the experiment in Hungary, fourteen per cent, of the 

 protected animals were dead mostly in consequence of 

 the second protective vaccination ; ninety-four per cent, of 

 the non-vaccinated died. In Prussia the result was more 

 favorable : 3 out of 25 sheep (twelve per cent.) died after 

 the second protective vaccination. After the final in- 

 oculation with fresh blood, all of the non-vaccinated, but 

 not one of the vaccinated, died. Pasteur thus demon- 

 strated that sheep at least may acquire increased power 

 of resistance to subcutaneous inoculation with anthrax ; 

 but he demonstrated at the same time that his protective 

 vaccination destroyed almost as large a per cent, of 

 animals as usually die from spontaneous infection in the 

 pasture. Since that time Pasteur seems to have em- 

 ployed less virulent material, for according to accounts 

 in French journals the mortality from the protective vac- 



