187T— 1879 261 



given them by Davaine, are living beings capable of being in- 

 definitely reproduced in appropriate liquids, after the manner 

 of a plant multiplied by successive cuttings. The bacterium 

 does not reproduce itself only under the filamentous form, but 

 also through spores or germs, after the manner of many plants 

 which present two modes of reproduction, by cuttings and by 

 seeds/* The first point was therefore settled. The ground 

 suspected and indicated by Davaine was now part of the domain 

 of science, and preserved from any new attacks. 



Yet Jaillard and Leplat's experiments remained to be ex- 

 plained: how had they provoked death through the blood of a 

 splenic fever victim and found no bacteridia afterwards? It 

 was then that Pasteur, guided, as Tyndall expressed it, by 

 **his extraordinary faculty of combining facts with the reasons 

 of those facts,'* placed himself, to begin with, in the condi- 

 tions of Jaillard and Leplat, who had received, during the 

 height of the summer, some blood from a cow and a sheep 

 which had died ©f anthrax, that blood having evidently been 

 abstracted more than twenty-four hours before the experiment. 

 Pasteur, who had arranged to go to the very spot, the knacker's 

 yard near Chartres, and himself collect diseased blood, wrote 

 to ask that the carcases of animals which had died of splenic 

 fever should be kept for him for two or three days. 



He arrived on June 13, 1877, accompanied by the veterinary 

 surgeon, M. Boutet. Three carcases were awaiting him: that 

 of a sheep which had been dead sixteen hours, that of a horse 

 whose death dated from the preceding day, and that of a cow 

 which must have been dead for two or three days, for it had 

 been brought from a distant village. The blood of the recently 

 diseased sheep contained bacteridia of anthrax only. In the 

 blood of the horse, putrefaction vibriones were to be found, 

 besides the bacteridia, and those vibriones existed in a still 

 greater proportion in the blood of the cow. The sheep's blood, 

 inoculated into guinea-pigs, provoked anthrax with pure bac- 

 teridia ; that of the cow and of the horse brought a rapid death 

 with no bacteridia. 



Henceforth what had happened in Jaillard and Leplat *s ex- 

 periments, and in the incomplete and uncertain experiments 

 of Davaine, became simple and perfectly clear to Pasteur, as 

 well as the confusion caused by another experimentalist who 

 had said his say ten years after the discussions of Jaillard, 

 Tje©lat and Davaine 



