264 "SPECIFIC TREATMENT" OF DISEASE 



of the calf. Pasteur, with this observation in mind, 

 sought to lower the virulence of the anthrax bacil- 

 lus which he had learnt to cultivate in suitable 

 media in the laboratory. By prolonged cultivation 

 of the bacilli at temperatures higher than those at 

 which they grew luxuriantly, he succeeded in grad- 

 ing their virulence. Whereas the original stock of 

 bacilli, even in very small doses, was fatal for 

 sheep inoculated with it, he found that the cultures 

 grown at high temperatures exerted no such effect. 

 The most attenuated (ist vaccine) only killed 

 highly susceptible mice slowly, the less attenuated 

 (2nd vaccine) killed mice and rabbits, and usually 

 had but a slight effect on sheep. Pasteur found 

 that by inoculating sheep with the 1st vaccine, 

 followed after some days by the 2nd vaccine, he 

 could render the sheep resistant against inocula- 

 tion with fully virulent strains of bacilli. These 

 observations, followed by those of many other 

 workers, on different diseases led to results of 

 immense practical importance. Lister, in Eng- 

 land, applied the discoveries of Pasteur to the 

 prevention of wound infection with results that 

 ushered in a revolution in surgical methods which 

 has benefited man throughout the world by saving 

 untold thousands of lives. 



In the years that followed, the impulse given 

 by Pasteur was seen at work in different countries. 

 Pasteur had made discoveries on the disease of 

 silkworms in France, on septicemia in fowls and 



