And yet some adversaries should have been struck by the efforts of a mind which, while marching forward to establish new facts, was ever seeking arguments against itself, and turned back to strengthen points which seemed yet weak. In November, Pasteur returned to his studies on fermentations in general and lactic fermentation in particular. Endeavouring to bring into evidence the animated nature of the lactic ferment, and to indicate the most suitable surroundings for the self-development of that ferment, he had come across some complications which hampered the purity and the progress of that culture. Then he had perceived another fermentation, following upon lactic fermentation and known as butyric fermentation. As he did not immediately perceive the origin of this butyric acid—which causes the bad smell in rancid butter—he ended by being struck by the inevitable coincidence between the (then called) infusory animalculæ and the production of this acid.
“The most constantly repeated tests,” he wrote in February, 1861, “have convinced me that the transformation of sugar, mannite and lactic acid into butyric acid is due exclusively to those Infusories, and they must be considered as the real butyric ferment.” Those vibriones that Pasteur described as under the shape of small cylindric rods with rounded ends, sliding about, sometimes in a chain of three or four articles, he sowed in an appropriate medium, as he sowed beer yeast. But, by a strange phenomenon, “those infusory animalculæ,” he said, “live and multiply indefinitely, without requiring the least quantity of air. And not only do they live without air, but air actually kills them. It is sufficient to send a current of atmospheric air during an hour or two through the liquor where those vibriones were multiplying to cause them all to perish and thus to arrest butyric fermentation, whilst a current of pure carbonic acid gas passing through that same liquor hindered them in no way. Thence this double proposition,” concluded Pasteur; “the butyric ferment is an infusory; that infusory lives without free oxygen.” He afterwards called anaërobes those beings which do not require air, in opposition to the name of aërobes given to other microscopic beings who require air to live.
Biot, without knowing all the consequences of these studies, had not been long in perceiving that he had been far too sceptical, and that physiological discoveries of the very first rank would be the outcome of researches on so-called spontaneous generation. He would have wished, before he died, not only that Pasteur should be the unanimously selected candidate for the 1861 Zecker prize in the Chemistry Section, but also that his friend, forty-eight years younger than himself, should be a member of the Institute. At the beginning of 1861, there was one vacancy in the Botanical Section. Biot took advantage of the researches pursued by Pasteur within the last three years, to say and to print that he should be nominated as a candidate. “I can hear the commonplace objection: he is a chemist, a physicist, not a professional botanist.... But that very versatility, ever active and ever successful, should be a title in his favour.... Let us judge of men by their works and not by the destination more or less wide or narrow that they have marked out for themselves. Pasteur made his début before the Académie in 1848, with the remarkable treatise which contained by implication the resolution of the paratartaric acid into its two components, right and left. He was then twenty-six; the sensation produced is not forgotten. Since then, during the twelve years which followed, he has submitted to your appreciation twenty-one papers, the last ten relating to vegetable physiology. All are full of new facts, often very unexpected, several very far reaching, not one of which has been found inaccurate by competent judges. If to-day, by your suffrage, you introduce M. Pasteur into the Botanical Section, as you might safely have done for Théodore de Saussure or Ingenhousz, you will have acquired for the Académie and for that particular section an experimentalist of the same order as those two great men.”
Balard, who in this academic campaign made common cause with Biot, was also making efforts to persuade several members of the Botanical Section. He was walking one day in the Luxembourg with Moquin-Tandon, pouring out, in his rasping voice, arguments in favour of Pasteur. “Well,” said Moquin-Tandon, “let us go to Pasteur’s, and if you find a botanical work in his library I shall put him on the list.” It was a witty form given to the scruples of the botanists. Pasteur only had twenty-four votes; Duchartre was elected.
The study of a microscopic fungus, capable by itself of transforming wine into vinegar, the bringing to light of the action of that mycoderma, endowed with the power of taking oxygen from air and fixing it upon alcohol, thus transforming the latter into acetic acid; the most ingenious experiments to demonstrate the absolute and exclusive power of the little plant, all gave reason to Biot’s affirmation that such skill in the observation of inferior vegetables equalled any botanist’s claim. Pasteur, showing that the interpretations of the causes which act in the formation of vinegar were false, and that alone the microscopic fungus did everything, was constantly dwelling on this power of the infinitesimally small. “Mycoderma,” he said, “can bring the action of combustion of the oxygen in air to bear on a number of organic materia. If microscopic beings were to disappear from our globe, the surface of the earth would be encumbered with dead organic matter and corpses of all kinds, animal and vegetable. It is chiefly they who give to oxygen its powers of combustion. Without them, life would become impossible because death would be incomplete.”
Pasteur’s ideas on fermentation and putrefaction were being adopted by disciples unknown to him. “I am sending you,” he wrote to his father, “a treatise on fermentation, which was the subject of a recent competition at the Montpellier Faculty. This work is dedicated to me by its author, whom I do not know at all, a circumstance which shows that my results are spreading and exciting some attention.
“I have only read the last pages, which have pleased me; if the rest is the same, it is a very good résumé, entirely conceived in the new direction of my labours, evidently well understood by this young doctor.
“M. Biot is very well, only suffering a little from insomnia. He has, fortunately for his health, finished that great account of my former results which will be the greatest title I can have to the esteem of scientists.”
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 I have now followed, I questioned my memory and endeavoured to revive their advice, and it seemed to me that they would not have disowned me.”
M. Duclaux said about this meeting: “Pasteur has since then won many oratorical victories. I do not know of a greater one than that deserved by that acute and penetrating improvisation. He was still much heated as we were walking back to the Rue d’Ulm, and I remember making him laugh by asking him why, in the state of mind he was in, he had not concluded by hurling his wooden crystals at his adversaries’ heads.”