The life of Pasteur

by René Vallery-Radot

As soon as Pasteur’s glass houses arrived, they were put up in the little vineyard he possessed, two kilometres from Arbois. While they were being put together, he examined whether the yeast germs were really absent from the bunches of green grapes; he had the satisfaction of seeing that it was so, and that the particular branches which were about to be placed under glass did not bear a trace of yeast germs. Still, fearing that the closing of the glass might be insufficient and that there might thus be a danger of germs, he took the precaution, “while leaving some bunches free, of wrapping a few on each plant with cotton wool previously heated to 150° C.”

He then returned to Paris and his studies on anthrax, whilst patiently waiting for the ripening of his grapes.

Besides M. Chamberland, Pasteur had enrolled M. Roux, the young man who was so desirous of taking part in the work at the laboratory. He and M. Chamberland were to settle down at Chartres in the middle of the summer. A recent student of the Alfort Veterinary School, M. Vinsot, joined them at his own request. M. Roux has told of those days in a paper on Pasteur’s Medical Work:

“Our guide was M. Boutet, who had unrivalled knowledge of the splenic fever country, and we sometimes met M. Toussaint, who was studying the same subject as we were. We have kept a pleasant memory of that campaign against charbon in the Chartres neighbourhood. Early in the morning, we would visit the sheepfolds scattered on that wide plateau of the Beauce, dazzling with the splendour of the August sunshine; then necropsies took place in M. Rabourdin’s knacker’s yard or in the farmyards. In the afternoon, we edited our experiment notebooks, wrote to Pasteur, and arranged for new experiments. The day was well filled, and how interesting and salutary was that bacteriology practised in the open air!

“On the days when Pasteur came to Chartres, we did not linger over our lunch at the Hôtel de France; we drove off to St. Germain, where M. Maunoury had kindly put his farm and flocks at our disposal. During the drive we talked of the week’s work and of what remained to be done.

“As soon as Pasteur left the carriage he hurried to the folds. Standing motionless by the gate, he would gaze at the lots which were being experimented upon, with a careful attention which nothing escaped; he would spend hours watching one sheep which seemed to him to be sickening. We had to remind him of the time and to point out to him that the towers of Chartres Cathedral were beginning to disappear in the falling darkness before we could prevail upon him to come away. He questioned farmers and their servants, giving much credit to the opinions of shepherds, who on account of their solitary life, give their whole attention to their flocks and often become sagacious observers.”

When again at Arbois, on September 17, Pasteur began to write to the Minister of Agriculture a note on the practical ideas suggested by this first campaign. A few sheep, bought near Chartres and gathered in a fold, had received, amongst the armfuls of forage offered them, a few anthrax spores. Nothing had been easier than to bring these from the laboratory, in a liquid culture of bacteria, and to scatter them on the field where the little flock grazed. The first meals did not give good scientific results, death was not easily provoked. But when the experimental menu was completed by prickly plants, likely to wound the sheep on their tongue or in their pharynx, such, for instance, as thistles or ears of barley, the mortality began. It was perhaps not as considerable as might have been wished for demonstration purposes, but nevertheless it was sufficient to explain how charbon could declare itself, for necropsy showed the characteristic lesions of the so-called spontaneous splenic fever. It was also to be concluded therefrom that the evil begins in the mouth, or at the back of the throat, supervening on meals of infected food, alone or mixed with prickly plants likely to cause abrasion.

It was therefore necessary, in a department like that of Eure et Loir, which must be full of anthrax germs,—particularly on the surface of the graves containing carcases of animals which had fallen victims to the disease,—that sheep farmers should keep from the food of their animals plants such as thistles, ears of barley, and sharp pieces of straw; for the least scratch, usually harmless to sheep, became dangerous through the possible introduction of the germs of the disease.

“It would also be necessary” wrote Pasteur, “to avoid all probable diffusion of charbon germs through the carcases of animals dying of that disease, for it is likely that the department of Eure et Loir contains those germs in greater quantities than the other departments; splenic fever having long been established there, it always goes on, dead animals not being disposed of so as to destroy all germs of ulterior contagion.”

After finishing this report, Pasteur went to his little vineyard on the Besançon road, where he met with a disappointment; his precious grapes had not ripened, all the strength of the plant seemed to have gone to the wood and leaves. But the grapes had their turn at the end of September and in October, those bunches that were swathed in cotton wool as well as those which had remained free under the glass; there was a great difference of colour between them, the former being very pale. Pasteur placed grapes from the two series in distinct tubes. On October 10, he compared the grapes of the glass houses, free or swathed, with the neighbouring open-air grapes. “The result was beyond my expectations; the tubes of open-air grapes fermented with grape yeast after a thirty-six or forty-eight hours’ sojourn in a stove from 25° C. to 30° C.; not one, on the contrary, of the numerous tubes of grapes swathed in cotton wool entered into alcoholic fermentation, neither did any of the tubes containing grapes ripened free under glass. It was the experiment described in my Studies on Beer. On the following days I repeated these experiments with the same results.” He went on to another experiment. He cut some of the swathed bunches and hung them to the vines grown in the open air, thinking that those bunches—exactly similar to those which he had found incapable of fermentation—would thus get covered with the germs of alcoholic ferments, as did the bunches grown in the open air and their wood. After that, the bunches taken from under the glass and submitted to the usual régime would ferment under the influence of the germs which they would receive as well as the others; this was exactly what happened.