“To pretend to express the relation between human variola and vaccine by speaking but of vaccine and its relations with cow pox and horse pox, without even pronouncing the word small-pox, is mere equivocation, done on purpose to avoid the real point of the debate.” Becoming excited by Guérin’s antagonism, Pasteur turned some of Guérin’s operating processes into ridicule with such effect that Guérin started from his place and rushed at him. The fiery octogenarian was stopped by Baron Larrey; the sitting was suspended in confusion. The following day, Guérin sent two seconds to ask for reparation by arms from Pasteur. Pasteur referred them to M. Béclard, Permanent Secretary to the Académie de Médicine, and M. Bergeron, its Annual Secretary, who were jointly responsible for the _Official Bulletin of the Academy_. “I am ready,” said Pasteur, “having no right to act otherwise, to modify whatever the editors may consider as going beyond the rights of criticism and legitimate defence.” In deference to the opinion of Messrs. Béclard and Bergeron, Pasteur consented to terminate the quarrel by writing to the chairman of the Academy that he had no intention of offending a colleague, and that in all discussions of that kind, he never thought of anything but to defend the exactitude of his own work. The _Journal de la Médecine et de la Chimie_, edited by M. Lucas-Championnière, said à propos of this very reasonable letter--“We, for our part, admire the meekness of M. Pasteur, who is so often described as combative and ever on the warpath. Here we have a scientist, who now and then makes short, substantial and extremely interesting communications. He is not a medical man, and yet, guided by his genius, he opens new paths across the most arduous studies of medical science. Instead of being offered the tribute of attention and admiration which he deserves, he meets with a raging opposition from some quarrelsome individuals, ever inclined to contradict after listening as little as possible. If he makes use of a scientific expression not understood by everybody, or if he uses a medical expression slightly incorrectly, then rises before him the spectre of endless speeches, intended to prove to him that all was for the best in medical science before it was assisted by the precise studies and resources of chemistry and experimentation.... Indeed, M. Pasteur’s expression of _equivocation_ seemed to us moderate!”