An experimental fact which occurred about that time was followed with interest, not only by the Académie des Sciences, but by the general public, whose attention was beginning to be awakened. A professor at the Nancy Faculty, M. Feltz, had announced to the Académie des Sciences in March, 1879, that, in the blood abstracted from a woman, who had died at the Nancy Hospital of puerperal fever, he had found motionless filaments, simple or articulated, transparent, straight or curved, which belonged, he said, to the genus _leptothrix_. Pasteur, who in his studies on puerperal fever had seen nothing of the kind, wrote to Dr. Feltz, asking him to send him a few drops of that infected blood. After receiving and examining the sample, Pasteur hastened to inform M. Feltz that that leptothrix was no other than the bacillus anthracis. M. Feltz, much surprised and perplexed, declared himself ready to own his error and to proclaim it if he were convinced by examining blood infected by charbon, and which, he said, he should collect wherever he could find it. Pasteur desired to save him that trouble, and offered to send him three little guinea-pigs alive, but inoculated, the one with the deceased woman’s blood, the other with the bacteridia of charbon-infected blood from Chartres, the third with some charbon-infected blood from a Jura cow. The three rodents were inoculated on May 12, at three o’clock in the afternoon, and arrived, living, at Nancy, on the morning of the thirteenth. They died on the fourteenth, in the laboratory of M. Feltz, who was thus able to observe them with particular attention until their death. “After carefully examining the blood of the three animals after their death, I was unable,” said M. Feltz, “to detect the least difference; not only the blood, but the internal organs, and notably the spleen, were affected in the same manner.”... “It is a certainty to my mind,” he wrote to Pasteur, “that the contaminating agent has been the same in the three cases, and that it was the bacteridium of what you call anthrax.” There was therefore no such thing as a leptothrix puerperalis. And it was at a distance, without having seen the patient, that Pasteur said: “That woman died of charbon.” With an honourable straightforwardness, M. Feltz wrote to the Académie des Sciences relating the facts.