One or two days before the third and decisive inoculation, the veterinary surgeon of Pont-sur-Yonne, M. Biot, who was watching with a rare scepticism the Pouilly le Fort experiments, met Colin on the road to Maisons-Alfort. “Our conversation”--M. Biot dictated the relation of this episode to M. Thierry, his colleague, also very sceptical and expecting the Tarpeian Rock--“our conversation naturally turned on Pasteur’s experiments. Colin said: ‘You must beware, for there are two parts in the bacteridia-culture broth: one upper part which is inert, and one deep part very active, in which the bacteridia become accumulated, having dropped to the bottom because of their weight. The vaccinated sheep will be inoculated with the upper part of the liquid, whilst the others will be inoculated with the bottom liquid, which will kill them.’” Colin advised M. Biot to seize at the last moment the phial containing the virulent liquid and to shake it violently, “so as to produce a perfect mixture rendering the whole uniformly virulent.” If Bouley had heard such a thing, he would have lost his temper, or he would have laughed heartily. A year before this, in a letter to M. Thierry, who not only defended but extolled Colin, Bouley had written: “No doubt Colin is a man of some value, and he has cleverly taken advantage of his position of Chief of the Anatomy department at Alfort to accomplish some important labours. But it is notable that his negative genius has ever led him to try and demolish really great work. He denied Davaine, Marey, Claude Bernard, Chauveau; now he is going for Pasteur.” Bouley, to whom Colin was indebted for his situation at Alfort, might have added, “And he calls me his persecutor!” But Biot refused to believe in Colin’s hostility and only credited him with scruples on the question of experimental physiology. Colin did not doubt M. Pasteur’s bona fides, M. Biot said, but only his aptitude to conduct experiments _in anima vili_. On May 31, every one was at the farm. M. Biot executed Colin’s indications and shook the virulent tube with real veterinary energy. He did more: still acting on advice from Colin, who had told him that the effective virulence was in direct proportion to the quantity injected, he asked that a larger quantity of liquid than had been intended should be inoculated into the animals. A triple dose was given. Other veterinary surgeons desired that the virulent liquid should be inoculated alternatively into vaccinated and unvaccinated animals. Pasteur lent himself to these divers requests with impassive indifference and without seeking for their motives.