212 DISCOVERY CH. 



rabic virus was contained in the saliva of the mad 

 animal. Pasteur wished to test this, and inoculated 

 rabbits with saliva from mad dogs, but the results were 

 inconclusive. It was then suggested that the symptoms 

 shown vby an animal or human being suifering from 

 hydrophobia indicated a connection with the nervous 

 system. Pasteur was thus led to use for his inoculations 

 an emulsion of the brain or spinal cord of a rabid animal, 

 instead of the saliva ; and in every case hydrophobia 

 occurred after inoculation. By attenuating the virus 

 and inoculating dogs with it in increasing strengths, he 

 was able to secure for them immunity against the bites 

 of rabid companions, and to find the period of incubation. 



This was his first step in making dogs refractory to 

 rabies by preventive inoculation ; the second was to 

 prevent the onset of rabies in dogs bitten or subjected 

 to inoculation. The period varies from about a fortnight 

 to seven or eight months, but the average length is six 

 weeks. A person bitten by a mad dog was thus haunted 

 for a long period by the anguish of uncertainty as to 

 whether the virus was developing in his system or not. 

 Pasteur believed that if such a person was inoculated, 

 with increasing strengths of the rabic virus during this ! 

 period, beginning within a few hours or days of the bite, 

 the system would be able to resist the onset of the disease 

 at a later stage. He could not test his conviction 

 deliberately by successive inoculations of a human 

 being, but an opportunity of treating an actual case of] 

 hydrophobia by this principle occurred in 1885. 



A young Alsatian boy, Joseph Meister, who had been I 

 badly bitten only two days before by a mad dog, was 

 brought to his laboratory. After careful consideration 

 and consultation with several leading physiologists and 

 physicians, Pasteur decided to apply anti-rabic inocula- 



