This was a Paris veterinary surgeon, M. Signol. He had written to the Academy of Sciences that it was enough that a healthy animal should be felled, or rather asphyxiated, for its blood, taken from the deeper veins, to become violently virulent within sixteen hours. M. Signol thought he had seen motionless bacteridia similar to the bacillus anthracis; but those bacteridia, he said, were incapable of multiplying in the inoculated animals. Yet the blood was so very virulent that animals rapidly succumbed in a manner analogous to death by splenic fever. A Commission was nominated to ascertain the facts; Pasteur was made a member of it, as was also his colleague Bouillaud--still so quick and alert, in spite of his eighty years, that he looked less like an old man than like a wrinkled young man--and another colleague, twenty years younger, Bouley, the first veterinary surgeon in France who had a seat at the Institute. The latter was a tall, handsome man, with a somewhat military appearance, and an expression of energetic good humour which his disposition fully justified. He was eager to help in the propagation of new ideas and discoveries, and soon, with eager enthusiasm, placed his marked talents as a writer and orator at Pasteur’s disposal. On the day when the Commission met, M. Signol showed the carcase of a horse, which he had sacrificed for this experiment, having asphyxiated it when in excellent health. Pasteur uncovered the deep veins of the horse and showed to Bouley, and also to Messrs. Joubert and Chamberland, a long vibrio, so translucid as to be almost invisible, creeping, flexible, and which, according to Pasteur’s comparison, slipped between the globules of the blood as a serpent slips between high grasses; it was the septic vibrio. From the peritoneum, where it swarms, that vibrio passes into the blood a few hours after death; it represents the vanguard of the vibriones of putrefaction. When Jaillard and Leplat had asked for blood infected with anthrax, they had received blood which was at the same time septic. It was septicæmia (so prompt in its action that inoculated rabbits or sheep perish in twenty-four or thirty-six hours) that had killed Jaillard and Leplat’s rabbits. It was also septicæmia, provoked by this vibrio (or its germs, for it too has germs), that M. Signol had unknowingly inoculated into the animals upon which he experimented. Successive cultures of that septic vibrio enabled Pasteur to show, as he had done for the bacillus anthracis, that one drop of those cultures caused septicæmia in an animal. But, while the bacillus anthracis is aërobic, the septic vibrio, being anaërobic, must be cultivated in a vacuum, or in carbonic acid gas. And, cultivating those bacteridia and those vibriones with at least as much care as a Dutchman might give to rare tulips, Pasteur succeeded in parting the bacillus anthracis and the septic vibrio when they were temporarily associated.