The vaccine used at Pouilly-le-Fort was made with an antiseptic, and the man who had first made an anthrax vaccine with an antiseptic was not at the farm. This piece is about him, and about the ten months before the trial in which his work and Pasteur’s ran side by side. Nearly everything in it comes from the Comptes rendus of 1880 and 1881 and from Gerald Geison’s reading of Pasteur’s notebooks and letters; the French is my translation.

The man in Toulouse

Jean-Joseph-Henri Toussaint was born on 30 April 1847 at Rouvres-la-Chétive in the Vosges, trained as a veterinarian, and in December 1876 was made professor of anatomy, physiology and zoology at the veterinary school of Toulouse. He was a pupil of Auguste Chauveau of Lyon, the leading French veterinary physiologist, and he had been at work on anthrax and on a disease of fowls for some years. In December 1878 it was Toussaint who sent Pasteur the blood of a cock dead of chicken cholera, from which Pasteur’s whole study of that disease, and his first vaccine, began. Pasteur thanked him, and let it be understood that his own methods were the better.

In the first days of July 1880 Henri Bouley, the inspector-general of the veterinary schools, visited Toulouse, heard what Toussaint had done, and went back to Paris with two documents: a note describing the results of a vaccine against anthrax, to be read to the Académie des sciences on 12 July, and a sealed envelope describing how the vaccine was made, to be deposited the same day. The sealed note, the pli cacheté, was the French way of establishing priority for a discovery without publishing it. Bouley could not keep the secret a week. On 6 July, in a discussion at the Académie de médecine, he let fall that a veterinarian in Toulouse had a vaccine, and Gabriel Colin of Alfort, who distrusted Pasteur, Bouley and microbes alike, complained of secret remedies and claimed priority himself.

The note of 12 July was read as planned. Toussaint reported eight young dogs, four vaccinated and four not: the four vaccinated had survived four successive inoculations of anthrax blood, the four controls had died of the first in two to four days with their lymph glands ten to fifteen times their size. Of eleven sheep of the Lauraguais breed, five inoculated once with anthrax had died in two or three days; of six vaccinated, one had died after a single vaccination, and the other five, vaccinated again, had since taken three inoculations of anthrax blood and one of spores without the least local or general effect, and two or three drops of rabbit’s blood into the facial vein, “about two hundred million bacteridia,” without harm. He had done it, he said, “with a means of great simplicity.” He did not say what. “I can at present vaccinate sheep which resist inoculations and intravascular injections of considerable quantities of bacteridia.”

The envelope opened

On 27 July the Académie de médecine spent a stormy session on whether its Bulletin could print a note about a remedy whose method was under seal, and in the course of it Pasteur’s name was joined to Toussaint’s as a purveyor of secret remedies, since Pasteur had announced his chicken cholera vaccine in February and had still not said how it was made. Pasteur, a member, threatened to resign and was placated. Toussaint, who was not a member and could not answer in the room, did the thing that distinguished him: he asked for his sealed note to be opened at once. It was read to the Académie des sciences on 2 August 1880.

It took a few lines. He had begun by filtering the defibrinated blood of animals dead of anthrax through ten or twelve sheets of paper, but the filters sometimes let bacteridia through, “and one kills the animals one wished to preserve.” So “I had recourse to heat to kill the bacteridia, and I brought the defibrinated blood to 55 degrees for ten minutes. The result was complete.” Five sheep given three cubic centimetres of the heated blood had since taken virulent anthrax without ill effect; but a single dose was not enough, and after one of two sheep died he had vaccinated the rest a second time. The idea behind it was Chauveau’s: that the bacillus, as it grew in the blood, left behind a soluble something that could act as a vaccine on its own, and that the heat killed the bacillus and left the something. It was a dead vaccine, or so its maker believed.

Pasteur was on holiday at Arbois, in the Jura, when the Comptes rendus reached him. On 10 August he wrote to Bouley, in Geison’s translation: “I have been in astonishment and admiration over the discovery of M. Toussaint—in admiration that it exists, in astonishment that it can be. It overturns all the ideas I had on viruses, vaccines, etc. I no longer understand anything.” Ten times, he said, he had thought of taking the train to Paris. He wrote to Chamberland and Roux, who were also on holiday, that they must give it up; Roux went to work in Paris, Chamberland joined Pasteur in the Jura. Pasteur’s account in March 1881 was that within three weeks they had the answer: blood heated at 55 degrees was not reliably dead. The bacillus sometimes lived through thirty minutes of it under a shallow depth of blood, “only modified in its vitality,” and it was the live, modified bacillus that protected; when the heat did kill, the blood protected nothing. Toussaint’s dead vaccine was a living one, badly controlled. On 20 August Pasteur sent the results to Bouley, who passed them to Toussaint.

Carbolic acid

Toussaint had already moved on, and this is the part Pasteur’s papers never told. Within days of sealing his note he had found that heated blood did not consistently work, and had started treating the blood with carbolic acid, the antiseptic Lister had made famous in surgery, at a low concentration, with or without the heat. On Sunday 8 August 1880 he and Bouley vaccinated twenty sheep with this carbolic vaccine at the Alfort veterinary school outside Paris. By Thursday 12 August four of the twenty were dead of anthrax and the other sixteen were seriously ill. Then the sixteen recovered, and when challenged with virulent anthrax they proved immune. On 19 August Bouley went to the rue d’Ulm, told Roux in confidence what had happened at Alfort, and heard that Roux was not surprised: he had been finding for days that heat at 55 degrees did not reliably kill the bacillus. Only then did Bouley tell him that the Alfort vaccine had been made not by heat but by “the measured action of carbolic acid.” Roux wrote to Pasteur that day that he expected the carbolic vaccine to turn out, like the heated one, to be a live and weakened bacillus.

The same day, 19 August, Toussaint addressed the French Association for the Advancement of Science at Reims, and in the printed version of that address, revised before publication, he gave up the dead vaccine and said that his vaccines worked by “an attenuated state of the parasite.” Pasteur and Bouley argued afterwards over whether he had said so at Reims or only after hearing of Roux’s results through Bouley; Geison found the evidence unfavourable to Toussaint. Two days later, on 21 August, Bouley and Toussaint called at the laboratory together and asked Roux for a virulent culture with which to test the immunity of the Alfort survivors. The tube they took away failed to kill a control rabbit. Roux worked out that they had taken, in place of fresh blood, a culture of spores Chamberland had made in July and left standing, and on 30 August he wrote to Pasteur a question that Pasteur underlined: might not many of the laboratory’s old cultures prove harmless to sheep and give them immunity, and in particular the cultures of spores “that Chamberland has left exposed for some time to gasoline vapours”? Agents other than air, in other words, might attenuate; and Toussaint had shown that an antiseptic could make a vaccine. Chamberland and Roux went looking for an antiseptic vaccine of their own.

Pasteur had tried antiseptics on the bacillus before. His notebooks of 1877, Geison found, record carbolic acid among them, and the conclusion that prolonged exposure killed. Davaine, who had discovered the bacillus, had claimed in 1873 that a range of antiseptics rendered anthrax blood harmless. None of that was in print under Pasteur’s name, and none of it went into print now. By 13 April 1881 Chamberland had a vaccine attenuated with potassium bichromate that protected sheep more surely than Pasteur’s air-attenuated culture, and it was that vaccine, strengthened by three passages through mice, that went into the sheep at Pouilly-le-Fort.

What was published

Pasteur’s paper of 28 February 1881 announced the air method and promised to show, when Toussaint published, “the uncertainty of the one, the sureness of the other.” The paper of 21 March was the showing. It granted Toussaint “the perfect exactness of his remarkable observation” that preventive inoculation was possible, and then dismantled the rest: the heated blood might be dead, alive, or modified, and only direct trial could tell which; the modified bacillus could not be fixed by culture, since its cultures went back to full virulence, “which distinguishes it essentially from the attenuated microbes of chicken cholera”; a flock vaccinated by Toussaint’s method “might be exposed to great losses,” and the method needed large quantities of anthrax blood. All of it was about heat. Carbolic acid, which Toussaint had been using since August and Pasteur had known about since Roux’s letter of 19 August, is not mentioned. Nor, in anything Pasteur published in 1881, is bichromate. When Chamberland and Roux described the antiseptic vaccines to the Académie on 9 April 1883 they said the work had been done under Pasteur’s direction and did not name the farm.

Pasteur recommended Toussaint for an academy prize, and in 1882 he received one. His health had broken the year before; a nervous disease that was never diagnosed with certainty took his mind, he published nothing after 1882, was put on leave from Toulouse in 1887, and died there on 3 August 1890, at forty-three. Geison, who thought his methods crude and Pasteur’s criticisms of them mostly fair, gave him the last word in a different sense: the first artificial vaccine whose recipe the world was allowed to read was Toussaint’s, because he opened his envelope the week it was questioned.

Sources

• H. Toussaint, “De l’immunité pour le charbon, acquise à la suite d’inoculations préventives,” Comptes rendus de l’Académie des sciences 91 (12 July 1880), 135–137, and “Procédé pour la vaccination du mouton et du jeune chien,” the sealed note opened at the session of 2 August 1880, Comptes rendus 91, 303–304. The French of the passages translated: “un moyen d’une grande simplicité”; “je puis vacciner actuellement des moutons qui résistent aux inoculations et aux injections intra-vasculaires de quantités considérables de bactéridies”; “environ deux cents millions de bactéridies”; “l’on tue les animaux que l’on voulait préserver”; “j’ai eu recours à la chaleur pour tuer les bactéridies et j’ai porté le sang défibriné à 55° pendant dix minutes. Le résultat a été complet.” archive.org, archive.org
• Louis Pasteur, with Chamberland and Roux, “De l’atténuation des virus et de leur retour à la virulence” (28 February 1881) and “De la possibilité de rendre les moutons réfractaires au charbon par la méthode des inoculations préventives” (21 March 1881), read in the Œuvres de Pasteur, volume VI (Paris, 1933), pages 332–343. The French: “l’incertitude de l’une, la sûreté de l’autre”; “la parfaite exactitude de sa remarquable observation”; “seulement modifié dans sa vitalité”; “ce qui la distingue essentiellement … des microbes atténués du choléra des poules”; “on pourrait être exposé à de grandes pertes.” archive.org
• Ch. Chamberland and E. Roux, “Sur l’atténuation de la virulence de la bactéridie charbonneuse, sous l’influence des substances antiseptiques,” Comptes rendus 96 (9 April 1883), 1088–1091. archive.org
• Gerald L. Geison, The Private Science of Louis Pasteur (Princeton University Press, 1995), chapter 6: the visit of Bouley to Toulouse, the sessions of 6 and 27 July 1880, Pasteur’s letter to Bouley of 10 August 1880 (quoted at second hand in Geison’s translation; the original is in Pasteur’s Correspondance, which I did not reach), the Alfort trial of 8 August, Roux’s letters of 19 and 30 August, the Reims address, the notebooks of 1877, the comparison of 13 April 1881, the prize, and Toussaint’s decline. In copyright; quoted in short phrases. press.princeton.edu
• “Henry Toussaint,” French Wikipedia, for his birth, his posts, the carbolic acid, his leave of 1887 and his death, which it takes from Cornevin’s obituary of 1890 and Chauveau’s eulogy of 1900. Geison says he published two papers after 1881, the last in 1882; the Wikipedia article counts four in 1881 and none after. fr.wikipedia.org