RABIES 73 



By this twofold power, not only to bring down a 

 virus, point by point, from full virulence to non- 

 virulence, but also to exalt a virus, point by point, 

 from non- virulence to full virulence, he was able to 

 obtain his virus fixe, his standard virus. He was 

 able to have, in his hands, a virus of known strength. 

 He was able to measure out an exact dose of this 

 virus, calculated to produce a known effect on an 

 animal of known weight. And, as with fowl- 

 cholera and anthrax, so with rabies, he was able to 

 confer immunity, with a graduated series of attenua- 

 tions of the virus, against the disease itself. That 

 is to say, he could begin with a dose of complete 

 non-virulence : next day, a dose of minimum viru- 

 lence : next day, a dose one shade stronger : and 

 so on. By this method, he could advance, till the 

 patient was immunised against the disease itself. 

 The patient, guarded each day by the dose of the 

 previous day, would be able, on the last day of 

 the treatment, to take without harm a dose as 

 strong as anything that the disease itself could do 

 to him. The treatment would be carried out 

 during the time when the disease itself was latent 

 in the scar of the bite, locked up, asleep, inert. 

 Some day, it might be wanting to flare up. On 

 that day, it would find itself outwitted : the patient 

 so to speak would have had it already, by 

 instalments : he would have immunised himself, 



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