Historical sketch on Immunity 509 



principal results being controlled and verified. In France, this great 

 discovery was at once accepted by various investigators, though 

 others found occasion to manifest their scepticism. Abroad this [532] 

 discovery met with very lively opposition and this from the highest 

 authorities, who would not recognise the possibility either of attenuat- 

 ing the virus or of conferring immunity upon animals. The anthrax 

 bacillus can be grown for a very long time on culture media, the potato, 

 for example, without losing its pathogenic power in the slightest 

 degree. Therefore, it was said, this attenuation of virus can have no 

 actual existence. White rats that have resisted one or more inocu- 

 lations of the anthrax bacillus may die from a later inoculation of the 

 same micro-organism. Therefore there is no acquired immunity, etc. 

 The principles laid down by Pasteur are from every point of view of 

 such prime importance, that very numerous experiments were carried 

 out at once for the purpose of verifying their exactness and the 

 contest was not a long one. In the course of a few years it was 

 universally recognised that the attenuation of viruses, and also the 

 vaccination by attenuated micro-organisms, were realities which 

 henceforth cannot be denied and which must pass into the domain of 

 truths definitely acquired. An attempt was then made to extend these 

 fresh victories to the other infective diseases. Pasteur, Chamberland, 

 and Roux applied themselves to devising a method of vaccinating ani- 

 mals against anthrax and against rabic virus ; Pasteur and Thuillier 

 extended their researches on this subject to swine erysipelas. 

 From several other quarters the search for vaccines was instituted. 

 Toussaint made various attempts, at times crowned with success, to 

 immunise animals against anthrax by means of heated anthrax blood. 

 Arloing, Cornevin, and Thomas succeeded in vaccinating the Bovidae 

 against symptomatic anthrax. Loeffler was the first in Germany to 

 demonstrate that rabbits which had recovered from the disease set 

 up by the bacillus of mouse septicaemia acquired an immunity 

 against the attacks of this organism. It is not necessary to cite 

 further examples, so numerous have they become and so unanimously 

 confirmatory. 



After the first steps had been taken along this new path Pasteur 

 and his collaborators began to apply the knowledge they had gained 

 to the preparation of vaccines capable of giving practical results. 

 The two anti-anthrax vaccines and the two vaccines against swine 

 erysipelas were the fruit of these attempts. Here, again, numerous 

 objections were raised against these discoveries. Sheep which had 



