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to Paris from Alais in 1871, at the request of Pasteur, who 

 knew his family. Viala was then only twelve years old and 

 could barely read and write. Pasteur sent him to an evening 

 school and himself helped him with his studies ; the boy was 

 very intelligent and willing to learn. He became most useful 

 to Pasteur, who, in 1885, was glad to let him undertake a great 

 deal of the laboratory work, under the guidance of M. Koux ; 

 he was ultimately entrusted with all the trephining operations 

 on dogs, rabbits, and guinea-pigs. 



The letters written to him by Pasteur in 1884 show the exact 

 point reached at that moment by the investigations on hydro- 

 phobia. Many people already thought those studies advanced 

 enough to allow the method of treatment to be applied to 

 man. 



Pasteur wrote to Viala on September 19, " Tell M. Adrien 

 (Loir) to send the following telegram : ' Surgeon Symonds, 

 Oxford, England. Operation on man still impossible. No 

 possibility at present of sending attenuated virus.* See MM. 

 Bourrel and Be*raud, procure a dog which has died of street- 

 rabies, and use its medulla to inoculate a new monkey, two 

 guinea-pigs and two rabbits. ... I am afraid Nocard's 

 dog cannot have been rabid ; even if you were sure that he 

 was, you had better try those tests again. 



" Since M. Bourrel says he has several mad dogs at present, 

 you might take two couple of new dogs to his kennels ; when 

 he has a good biting dog, he can have a pair of our dogs bitten, 

 after which you will treat one of them so as to make him 

 refractory (carefully taking note of the time elapsed between 

 the bites and the beginning of the treatment). Mind you keep 

 notes of every new experiment undertaken, and write to me 

 every other day at least." 



Pasteur pondered on the means of extinguishing hydrophobia 

 or of merely diminishing its frequency. Could dogs be vacci- 

 nated ? There are 100,000 dogs in Paris, about 2,500,000 

 more in the provinces : vaccination necessitates several pre- 

 ventive inoculations ; innumerable kennels would have to be 

 built for the purpose, to say nothing of the expense of keeping 

 the dogs and of providing a trained staff capable of performing 

 the difficult and dangerous operations. And, as M. Nocard 

 truly remarked, where were rabbits to be found in sufficient 

 number for the vaccine emulsions? 



Optional vaccination did not seem more practicable ; it could 



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