238 PASTEUR : THE HISTORY OF A MIND 



applying himself to the demonstration of the fact that 

 the bacteridium was the sole cause of anthrax. Without 

 entering into the details or the chronology of his mem- 

 oirs on this subject, it will suffice here to point out the 

 status to which he had brought the question at -the time 

 when Pasteur attacked it in so masterly a manner. 



It can be said that Davaine had perfectly demon- 

 strated the coexistence of the bacteridium and of the 

 anthrax. This fact of coexistence which is not, how- 

 ever, necessarily to be considered a relation of cause 

 and effect, became known as the result of a long series 

 of observ^ations made on cases of malignant pustule, 

 which is the most common form of anthrax in man, as 

 well as on animals killed by anthrax either naturally, or 

 as a result of artificial infection. This coexistence had 

 been disputed. After Brauell, Signol, Leplat and Jail- 

 lard, Bouley and Sanson had pubhshed observations 

 or experiments in which anthrax seemed to be present 

 and the bacteridium absent. But Davaine had replied 

 to this by showing that these scientists either had failed 

 to recognize the bacteridium or else had called something 

 anthrax which was not anthrax. 



Leplat and Jaillard, for example, imparted a deadly 

 malady to rabbits by inoculating them with i)utrid 

 blood from an anthrax victim, or in default of that, with 

 bacteria of putrefaction, and did not find bacteridia 

 in the blood of the dead animals. "Nothing is less 

 astonishing," replied Davaine, "your malady, and also 

 that of Signol, is not anthrax. It differs from the latter 

 in its shorter incubation period, because it is accom- 

 panied neither by the agglutination of the blood-cor- 

 puscles nor the congestion of the spleen, the most con- 

 stant and characteristic symptoms of anthrax, and 

 because it kills birds, on which the bacteridium has no 

 effect. Do not be surprised, therefore, that in this new 



