THE ATTENUATED VIEUS, OK VACCINATION. 229 



restore to the system, and which to the most deadly 

 contagium is a condition of life. The impossibility 

 of action of the progressive virus and of the deadly 

 virus is thus accounted for. 



When Pasteur communicated to the Academy of 

 Sciences these important and unforeseen facts, they 

 were at first received with hesitation. It was not 

 without some surprise that the word vaccination, 

 hitherto exclusively reserved for Jenner's discovery, 

 was heard applied to fowl cholera. At the Inter- 

 national Medical Congress held in London in August 

 1881, Pasteur, in the presence of 3,000 doctors 

 of medicine from all parts of the world, who received 

 him with an enthusiasm which reflected glory on 

 France, justified the name that he had given to his 

 prophylactic experiments. 



' I have lent,' he said, ' to the expression vaccina- 

 tion an extension that I hope science will consecrate, 

 as a homage to the merit and immense services 

 rendered to humanity by one of the greatest men of 

 England Jenner.' 



Still, while rendering homage to the sentiment 

 which induced Pasteur to efface himself in favour of 

 Jenner, we may be permitted to say that there is no 

 likeness between the two discoveries. Great as was the 

 discovery of Jenner, it was but a chance observation, 

 which had no ulterior development ; and for a whole 

 century, medicine has not been able to derive anything 



