Biot died without having realized his last wish, which was to have Pasteur for a colleague. It was only at the end of the year 1862 that Pasteur was nominated by the Mineralogical Section for the seat of Senarmont. This new candidature did not go without a hitch. In his study on tartrates, Pasteur, as will be remembered, had discovered that their crystalline forms were hemihedral. When he examined the characteristic faces, he held the crystal in a particular way and said: “It is hemihedral on the right side.” A German mineralogist, named Rammelsberg, holding the crystal in the opposite direction, said: “It is hemihedral on the left side.” It was a mere matter of conventional orientation; nothing was changed in the scientific results announced by Pasteur. But some adversaries made a weapon of that inverted crystal; not a dangerous weapon, thought Pasteur at first, fancying that a few words would clear the misunderstanding. But the campaign persisted, with insinuations, murmurs, whisperings. When Pasteur saw this simple difference in the way the crystal was held stigmatised as a cause of error, he desired to cut short this quarrel made in Germany. He then had with him no longer Raulin, but M. Duclaux, who was beginning his scientific life. M. Duclaux remembers one day when Pasteur, seeing that incontrovertible arguments were required, sent for a cabinet maker with his tools. He superintended the making of a complete wooden set of the crystalline forms of tartrates, a gigantic set, such as Gulliver might have seen in Brobdingnag if he had studied geometrical forms in that island. A coating of coloured paper finished the work; green paper marked the hemihedral face. A member of the Philomathic Society, Pasteur asked the Society to give up the meeting of November 8, 1862, to the discussion of that subject. Several of his colleagues vainly endeavoured to dissuade him from that intention; Pasteur hearkened to no one. He took with him his provision of wooden crystals, and gave a vivid and impassioned lecture. “If you know the question,” he asked his adversaries, “where is your conscience? If you know it not, why meddle with it?” And with one of his accustomed sudden turns, “What is all this?” he added. “One of those incidents to which we all, more or less, are exposed by the conditions of our career; no bitterness remains behind. Of what account is it in the presence of those mysteries, so varied, so numerous, that we all, in divers directions, are working to clear? It is true I have had recourse to an unusual means of defending myself against attacks not openly published, but I think that means was safe and loyal, and deferential towards you. And,” he added, thinking of Biot and Senarmont, “will you have my full confession? You know that I had during fifteen years the inestimable advantage of the intercourse of two men who are no more, but whose scientific probity shone as one of the beacons of the Académie des Sciences. Before deciding on the course