384 LOUIS PASTEUR 



vibrio by the atmospheric oxygen dissolved in the fluids. 

 The Academy may remember that I have previously demon- 

 strated facts of this nature in regard to the vibrio of butyric 

 fermentation, which not only lives without air but is killed 

 by the air. 



It was necessary therefore to attempt to cultivate the 

 septic vibrio either in a vacuum or in the presence of inert 

 gases such as carbonic acid. 



Results justified our attempt ; the septic vibrio grew easily 

 in a complete vacuum, and no less easily in the presence 

 of pure carbonic acid. 



These results have a necessary corollary. If a fluid con- 

 taining septic vibrios be exposed to pure air, the vibrios 

 should be killed and all virulence should disappear. This 

 is actually the case. If some drops of septic serum be 

 spread horizontally in a tube and in a very thin layer, the 

 fluid will become absolutely harmless in less than half a 

 day, even if at first it was so virulent as to produce death 

 upon the inoculation of the smallest portion of a drop. 



Furthermore all the vibrios, which crowded the liquid 

 as motile threads, are destroyed and disappear. After 

 the action of the air, only fine amorphous granules can be 

 found, unfit for culture as well as for the transmission 

 of any disease whatever. It might be said that the air 

 burned the vibrios. 



If it is a terrifying thought that life is at the mercy 

 of the multiplication of these minute bodies, it is a con- 

 soling hope that Science will not always remain powerless 

 before such enemies, since for example at the very be- 

 ginning of the study we find that simple exposure to air 

 is sufficient at times to destroy them. 



But, if oxygen destroys the vibrios, how can septicemia 

 exist, since atmospheric air is present everywhere? How 

 can such facts be brought in accord with the germ theory? 

 How can blood, exposed to air, become septic through 

 the dust the air contains? 



All things are hidden, obscure and debatable if the cause 

 of the phenomena be unknown, but everything is clear 

 if this cause be known. What we have just said is true 

 only of a septic fluid containing adult vibrios, in active 





