400 THE LIFE OF PASTEUR 



many other men interested in scientific things, who had come 

 1o hear him describe the steps by which he had made such 

 secure progress in the arduous question of hydrophobia. He 

 began by a declaration of war against the prejudice by which 

 so many people believe that rabies can occur spontaneously. 

 Whatever the pathological, physiological, or other conditions 

 may be under which a dog or another animal is placed, rabies 

 never appears if the animal has not been bitten or licked by 

 another rabid animal ; this is so truly the case that hydrophobia 

 is unknown in certain countries. In order to preserve a whole 

 land from the disease, it is sufficient that a law should, as in 

 Australia, compel every imported dog to be in quarantine for 

 several months; he would then, if bitten by a mad dog before 

 his departure, have ample time to die before infecting other 

 animals. Norway and Lapland are equally free from rabies, a 

 few good prophylactic measures being sufficient to avert the 

 scourge. 



It will be objected that there must have been a first rabid 

 dog originally. ''That," said Pasteur, "is a problem which 

 cannot be solved in the present state of knowledge, for it par- 

 takes of the great and unknown mystery of the origin of life.^' 



The audience followed with an impassioned curiosity the 

 history of the stages followed by Pasteur on the road to his 

 great discovery: the preliminary experiments, the demonstra- 

 tion of the fact that the rabic virus invades the nervous centres, 

 the culture of the virus within living animals, the attenua- 

 tion of the rabic virus when passed from dogs to monkeys, and 

 simultaneously with this graduated attenuation, a converse 

 process by successive passages from rabbit to rabbit, the pos- 

 sibility of obtaining in this way all the degrees of virulence, 

 and finally the acquired certainty of having obtained a pre- 

 ventive vaccine against canine hydrophobia. 



"Enthusiastic applause," wrote the reporter of the Journal 

 des Dehats, "greeted the conclusion of the indefatigable 

 worker." 



In the course of one of the excursions arranged for the 

 members of the Congress, Pasteur had the pleasure of seeing 

 his methods applied on a large scale, not as in Italy to the 

 progress of sericiculture, but to that of the manufacture of 

 beer. J. C. Jacobsen, a Danish citizen, whose name was 

 celebrated in the whole of Europe by his munificent donations 

 ko science, had founded in 1847 the Carlsberg Brewery, now 



