Contribution to the knowledge of relations between Koch and Pasteur
by
 H.H. Mollaret

  NTM-Schriftenr. Gesch. Naturwiss, Technik, Med, Leipzig 20 (1983)1, S 57-65

 (Translated by E. T. Cohn, B. H. Fasciotto-Dunn, U. Kuhn and D. V. Cohn)

Better say it right away; the relationship between Koch and Pasteur was hateful.   After having illustrated it, we will try to understand why.

The first meeting of the two scientists was in London, August 1881, during the International Congress of Medicine.  Pasteur, then 59 years old, has behind him a prestigious series of work and discoveries on fermentation, spontaneous generation, silkworm’s disease, studies on wine and beer, anthrax, immunization against chicken cholera and the general principle of bacterial attenuation.  Koch is 38 years old.  Even if he began research only since 1873, he was already famous for his works on wound infection and on anthrax; the discovery of the anthrax spore gave him 6 years earlier and exceptional reputation; for the past 2 years he is a member of the Reichsgesundtheitsamt.

At this London congress, Pasteur presented his results on viral attenuation; he then attends, in Lister’s laboratory, at King’s College, a series of demonstrations by Koch who presents his staining procedures and his films of various microorganisms.  Pasteur looks at them for a long time and says to Koch with admiration: “This is a great advance, Sir”.

Already, on April 30, 1877, at the Science Academy of Paris, Pasteur spoke warmly of Koch’s discovery of the anthrax spore, stating this his work was a “remarkable achievement”.

Apparently, nothing justified the violence of the attack against Pasteur, as much from Koch as from his students.  A few months after the London congress, the first volume of Mittheilungen aus dem Kaiserlichen gesundheitsamtes appears;  in this collection, Koch violently attacks not only the discovery of viral attenuation presented by Pasteur in London, but also the entire related work of Pasteur.  Thus in the paper Zur  Äetiologie de Milzbandes, Koch writes:

It is very likely that there are also other species of pathogenic germs, resembling the anthrax bacilli in terms of their length and width and which might also cause pathogenic processes similar to anthrax… This entire description proves that Pasteur had never thought of this questionable infectious disease in a simple way… After all the sentence that birds are immune to anthrax, can not be maintained especially because chickens, with which Pasteur performed his experiments, were susceptible to anthrax even without preparation by cooling; therefore Pasteur's statement about his experiment can't possibly be true: aside from the still open question in Pasteur's experiment if the claim that chickens became susceptible to anthrax by cooling, to which they had not been susceptible in the first place… In Pasteur's theory about the etiology of anthrax are only a few new findings that are mostly based on errors... To this point Pasteur's research on anthrax has not supported the etiology of this infectious disease at all…  Rather, we have the famous and quite ingenious theory of Pasteur about the importance of the earthworm for the etiology of anthrax and furthermore for many other infectious diseases. Even in Germany this earthworm theory of Pasteur has found many admirers.

And Koch explains why this theory, according to him, is untenable:

A condition sine qua non of Pasteur's earthworm‑theory is that the anthrax spores lay hidden deep in the earth....  One must recollect that absolutely necessary for spore formation are moisture and a certain temperature.  Deeper layers of the ground do not lack the moisture but the question remain if the temperature required for the spore formation exists... In the ground of Berlin at a depth of 3 meters this temperature can not be attained at any of the observation locations.

Koch concludes as to the naiveté of Pasteur’s theory on the role of the earthworm in anthrax:

The theory on the role of the earthworm in the etiology of anthrax, even as with earlier investigations of Pasteur turned out to be in error; and all the proofs from his anthrax studies allow one to summarize that up to now thanks to Pasteur our knowledge of anthrax has not been enlarged; thus in part his work in this field only confuses what is already fixed or is fast being clarified.

In the same book Löffler and Gallky also violently criticize Pasteur’s research: Löffler, in his paper Zur Immunitätsfrage attacks Pasteurian vaccination by attenuated germs, asserting that the cultures of the chicken cholera bacilli prepared by Pasteur weren’t pure because they were not done on gelatin, as recently introduced by Koch:

Not less susceptible to question than the purity of the cultures is the evidence of the reduction in virulence… This example shows that Pasteur’s investigation at its current state would hardly be usable in practice regardless of all other raised objections.

Löeffler then goes on to attack Pasteur’s work on anthrax:

With objective reflection of this brief work of Pasteur, one can not resist the impression, that his was rather a theoretical discussion than the result of experimental studies.... If we nevertheless accept Pasteur’s predicted and overall lucky experimental result [in Pouilly‑le‑Fort] with a conscious reserve, so this impression is not baseless.  The foundation on which Pasteur's investigation rests is the experimentally-supported allegation that Bacillus anthracis cannot form spores at 42‑43 °C in neutral chicken bouillon.  In his numerous experiments on the influence of the temperature on spore formation of Bacillus anthracis, Koch only has discovered irrefutably, and I was a witness many times, that the bacillus can strongly form spores at 42‑43 °C in a neutral clear chicken broth just as well as it is able to do at temperatures between 30 °C and 40 °C.

A translation of this attack was published in the February 20 1882's issue of the Revue of Hygiene and Sanitary Policy: this leads to a violent reaction from French scientists: H. Bouley publishes in the Recueil de Médecine vétérinaire of March 1882 an "Appreciation of Prof. Koch, from Berlin, on the works of Mr. Pasteur".  We know by the latter's letters how deeply he was touched by the criticisms of Koch. However, contrary to his habit, he does not respond immediately to them, waiting to do so on the occasion of a public meeting with Koch.

 This opportunity was furnished him during the IVth International Congress for Hygiene and Demography on September 5-9, 1882.

Soon after the London's international medical congress, where I introduced virus attenuation," recalls Pasteur, "was published in Berlin the first volume of a book on studies of the German Imperial Sanitary Office. Not only this discovery on attenuation, but also all my earlier research on disease microbes were attacked with a strange ferociousness by Dr. Koch and two of his students. I waited to respond for a favorable occasion; it was given to me in September 1882.  I went to Geneva, to the International Congress of Hygiene, with hope to meet with Dr. Koch.

 At this congress, Koch was imbued with the fame of his discovery of the tuberculosis germ that he had presented six months earlier in Berlin on March 21, 1882.  Pasteur made a lengthy presentation on the vaccination against anthrax, criticizing Koch’s opinion that pathogenic bacterial medication was impossible.

 …. one cannot question that we have a general method of attenuation. ... The general principles are found and one cannot deny that this line of research, in the future holds out the highest hopes.  But, as brilliant as is demonstrated truth, it is not always privileged to be readily accepted. I met stubborn contradictors in France and in foreign countries. Allow me to choose among them the person of merit who has the most right to our attention. I am talking about Dr. Koch, of Berlin.

 Pasteur summarizes and denies with vehemence the criticism published in the book of research of the German health office.  He hopes to engage in public discussion with Koch:

Perhaps, in this audience, there are some people who share the same thoughts as my contradictors. Allow me to invite them to speak up.

 While Pasteur was talking, Koch sitting next to Prof. Lichtheim, Chair of the medical clinic of Berne before being chair of Kongsberg, was showing his impatience, standing up and trying to disturb Pasteur while the audience was astounded.

 Koch declined all discussion.  Getting up on stage he made according to the Congress report, the following declaration:

Having the knowledge through the program of the congress that Mr. Pasteur would talk today about virus attenuation, I came in hopes of learning some new facts on a subject that interests me to the highest degree. I must admit now that I have been deceived in that there is nothing new in the presentation of Mr. Pasteur. I do not think it is necessary to answer here the attacks of Mr. Pasteur and this for two reasons: first, because the points in question affect only indirectly the hygiene issues, and second, because not knowing French well and Mr. Pasteur not knowing sufficient German, we could not start a fruitful discussion. I shall wait and answer Mr. Pasteur through the channels of medical journals.

 He did this three months later in a small publication: Über die Milzbrandimpfung. Eine Entgenung auf den von Pasteur in genf gehatenen Vortrag.  The violence of the attack was greater than the one in  which he presented arguments in "Mittheilungen aus dem Kaiserlichen Gesundhieitsamte".   Be the judge:

 [From Pasteur] only well know things were heard about chicken cholera, about the new rabies disease, and about the preventive vaccination against anthrax, that until then on so-and-so many thousand animals were vaccinated…. All this was apparently also a basis for a dispute directed against me, which was not restricted to the announced topic, but extended over all the differences on both side of our views in terms of the etiology of anthrax.  These in my opinion on the already answered questions on the cooling of chickens, the importance of the earthworms, etc., are not of essential interest to hygiene and a discussion about the same topics should not at all be a part of a general session of a hygiene congress, in particular the less as Pasteur’s polemic was not directed to defeat me by real proof, but by general phrases and to a major part personally direct against me in an angry tone… As a result of his poor methods Pasteur drifted off course immediately the moment he started to answer a new question on the contagion of rabies.  Pasteur could not find the rabies microbes, which one hoped to find at that time and which one looks for today.  So the methods followed by Pasteur must be called full or mistakes and cannot lead to successful results because they lack microscopic examinations, involve use of impure substances and use unsuitable experimental animals… Meanwhile Pasteur has only provoked criticism not only due to the poor quality of his methods, but also to the way in which he published his results… Whoever claims faith and confidence in the scientific world is duty-bound to publish the methods followed so that everybody is able to test their correctness… Rather, Pasteur used the tactic of telling only that much about his experiments that was in his favor, but he withheld everything that was unfavorable, even when it was important for the outcome of the experiment.

 Not lacking were even more personal attacks: after many others, Koch reproaches Pasteur for not being a physician (“kein Arzt zu sein”) or to make use of the assets that he is privy to:

We do not have that considerable series of experimental animals to show as Pasteur had with the help of his annual amount of funding.

 And Koch concluded thusly:

When Pasteur was celebrated as the second Jenner at the Congress in Genf, this occurred slightly prematurely.  Obviously in the desire to be enthusiastic it was forgotten that Jenner’s beneficial discovery was not in sheep but in humans.

 Pasteur's response, dated December 25, 1882, was simultaneously published in the volume of the Revue Scientific of January 20, 1883, preceded by a French translation of Koch's memoir, and in a brochure published in Paris by Baillière: "The Anthrax vaccination;  Response to Mr. Koch's memoir.”

The tone is as cutting as Koch’s:

This is another mistake on your part ... The day you would like to be informed on this point and on all the preceding points, I will be to your disposition during a congress or a commission where you can designate the members. If you accept … you may not be able to sustain the tone of assurance reflected in . . your brochure… You, Sir, who entered in Science, in 1876 only after all the famous names that I just mentioned, can recognize without derogation that you are a debtor of French Science" ... There are in your brochure numerous sec­tions where the impertinence or mistake, the way Pascal would say it, “is really too much."

  Essentially, Pasteur’s argumentation is solid and his presentation clever.  He recalls how, himself, emphasized again and again before the Academy of Science on April 30, 1877 the importance of Koch’s discovery of the anthrax spores in a remarkable paper. But this is to claim later his priority of his discovery of the spores in the earthworm disease:

 You can see, Sir, that I was one of the first to recognize the value of your work on the spores of B. anthrax ... Nevertheless, if you would go back to the first volume of my work on earthworm diseases, you would see… that the priority of the discovery of the formation of spores in a pathogenic bacillus belongs to me... Why, Sir, did you hide all this from the read­ers of your first memoir?  Would you say that you did not have knowledge of my paper... published in 1869‑70? Your assertion would have no significance because, in Science, no one is allow to ignore a discovery.

In 1884, after his discovery of Vibrio cholera, Koch is named member of the Prussian State Council and, with this title, travels to Paris and Toulon, in July. He visited various hospitals but did not go to the laboratory on Ulm Road where Pasteur works; (the institute will not be created until1888.) This exclusion did not stop Pasteur from sending a telegram to Koch with his congratulations for his presentation on  tuberculin at the congress of Medicine of Berlin, in August 1890.  In the same way, he defends Koch's discovery in the French scientific press:  The testimony of the Paris correspondent in the Deutsche Medizinische Wochenschrift who attended the presentation, reports the strength with which Pasteur defended his opponent:

On Monday the weekly session of the Science Academy took place, during which we discussed at length Koch’s publication.  Pasteur was present and was bombarded with questions.  He sharply rejected some participants that had doubts.  “there is nothing to discuss”, he screamed, with an energy that stopped all other questions and that warned the unconvinced that they should express no more doubts.

 When Pasteur published his results on rabies vaccination, the Berlin school under the influence of Koch was initially opposed, but a few years later Koch had to, himself, bow to the evidence of the results and organized at the Berlin Hygiene institute a rabies vaccination service in accord with the Pasteurean method. But he did not relent, however.  On 22 December 1892 most of the prominent European scientists attended the Jubilee for Pasteur's 70th birthday.  Perhaps some very personal matrimonial reasons (wife trouble, dvc) were the cause of Koch’s absence.

 Pasteur died 28 September 1895. Is it for this reason that at the time of his second voyage to Paris in October 1904, Koch no longer avoided visiting Pasteur's laboratories? According to Metchnikoff  the purpose of this second voyage was anything but scientific; the second Madam Koch desired to see Paris, its theaters, cabarets, restaurants and artists. Koch visits the Pasteur Institute where according to Metchnikoff, (The Founders of Modern Medicine,, Walden Publications, New York, 1939, p 122-123; D. Berger, transl.):

The welcome he received surpassed the one which was experienced by crowned heads. The staff assembled in the Library welcomed him with a salvo of applause.  Koch visited the laboratories, the stables and the rest: it is for the technical details that he manifested the most interest. He took note of the slightest improvements in the methods of bloodletting of horses, injections, etc.

 The papers of the time which reported at great length this visit to the Institute and to the  Garche annex failed to mention that the German savant returned to the crypt of the Institute where Pasteur was interred.

 Such were the relations of Koch and Pasteur. Is one able to attempt to advance some explanations of the antagonism between the two scientists?

 Indeed, it is necessary at first to emphasize the liveliness ‑ one isn't able to say less‑ of their spirit:  The polemic intensity of Pasteur, his need to convince, his harshness in discussion, his fits of anger are well known. Koch is authoritarian, entirely haughty. Here is how Metchnikoff, who was eventually closely connected to him, relates their first meeting (Ibid. pp 120 ff):

In 1887 at the Hygiene Congress of Vienna I met his principal assistant who told me that Koch wished to see the preparations regarding my last work on recurrent fever and that he asked that they be sent to send to him. Naturally, I didn't ask more and I added that instead of sending them, I would deliver them myself. Some well known bacteriologists of Munich advised me against this; they were convinced that I would be dismissed by Koch; that he didn't wish to see in my preparations what I found there, and that after having seen them, he would say thenceforth that he had established the lack of foundation in my conclusions with a full knowledge of the facts.  I didn't take notice of this warning and I returned to Berlin. There I met his assistants and his pupils. After having announced my visit to Koch, they arranged a meeting with him for the next day. Between times I had left my preparations and I showed them to his young collaborators. They affirmed unanimously that all that they saw in the microscope confirmed my conclusions without contradiction.  Encouraged, I returned to Koch's laboratory the next day.  I saw seated at the microscope a middle-aged man, not old ...his handsome face had a serious expression, nearly haughty. With great deference the assistant announced that I had arrived for the meeting which he had arranged and that I wished to show him my preparations. "What preparations?", said Koch in a gruff voice. I told you to prepare all that was necessary for my afternoon course and I see that many things are missing!"  The assistant excused himself humbly and introduced me again to Koch.  He, without offering his hand, said that he was very busy at this moment and that he was only able to devote a little time to the examination of my specimens.  One hurriedly gathered some microscopes and I showed him that which in my opinion was the most conclusive.  "Why then have you used a violet coloring when a blue coloring would have been better?"  I explained my motives, which scarcely softened him. After some moments, he got up and said that my preparations were not at all conclusive and that they in no way confirmed my point of view. Very offended by these words and by Koch's attitude, I answered that the few minutes time allotted weren't enough for him apparently to appreciate the delicacy of the preparations; and I asked for another, less brief meeting. At this time the assistant and the students who stood around us and who in my opinion were now in agreement with him.

It is curious to note that when Alexandre Yersin, Pasteur's collaborator and Dr. Roux's assistant returned to Berlin in June 1888 to pursue the teaching given at the Institute of Hygiene by Koch himself, he wasn't able to succeed in personally meeting him. In an unedited letter to his mother Yersin writes on June 29, 1888:

I am thinking of offering a copy of my thesis to the Grand Lama Koch whom I haven't seen yet and whom I would hope to see before leaving.

Yersin who had begun his medical studies in Marburg, spoke fluent German; his thesis devoted to "The Study on the Development of the Experimental Tubercle", would have wanted to arouse Koch's attention. Yersin left again without having met him. In another letter dated July 13, 1888 he writes:

I have now left Berlin on the morning of July first in order to arrive at Breslau the same day, in the evening, Breslau isn't a beautiful city and its surrounding neighborhoods very much resemble those of Berlin. Monday, I went to see Professor Flügge who has been very friendly and has shown me all I wished to see. He was formerly Koch's student and right hand. Today he is removed from Koch and a little more free in his thoughts, he begins to recognize that in France one has also done some interesting work. He particularly believes in the effectiveness of the  vaccinations against rabies, which is quite rare in Germany.

 To take account of the general climate of exacerbated patriotism which prevailed then in the scientific community, the quarrel between Koch and Pasteur on the subject of anthrax merely extended from a earlier quarrel that was placed on the patriotic plane: well before Koch and Pasteur the priority for the  discovery of the anthrax bacteria was attributed by French writers to Rayer and Davaine (1850); and by the Germans to Pollender who would have seen the bacteria since 1849 but only published his observations in 1855. This atmosphere of scientific chauvinism could be seen in nationalist sentiments of Koch and Pasteur: Koch, violently anti‑French, volunteered (for the Prussian Army) in 1870. Refused because of his nearsightedness, he in enlisted in 1871 and served in the Prussian army in Lorraine at first, then in a military hospital near Orleans.  A passionate patriot, Pasteur detested the Germans. After the war of 1870, writes Metchnikoff (Ibid p. 89 and In Mollaret, p:62)

When he received German books or brochures he held them at the tip of his fingers in order to pass them to me, or he put them aside with an air of repugnance. That didn't prevent him from agreeing to my proposition to send a congratulatory telegram to Koch concerning his discovery of the remedy against tuberculosis. The war of 1870 was a sorrow from which he was never able to recover.  At the time of general enthusiasm he wanted to become a volunteer in the National Guard and not leave Paris during the siege. His friends dissuaded him and he left for Arbois the morrow of Sedan and the fall of the empire.

 Pasteur writes at that time:

I wish that France will resist until her last man, until her last rampart! I wish that the war lasts until the heart of winter when the elements come to our aid, so that all these vandals will perish from cold, misery and sickness.  Each of my efforts until my last day will carry an epigraph: “Hatred of Prussia, Vengeance, Vengeance!” (Ibid, p 89).

 On January 18, 1871 Pasteur returns the diploma of Doctor of Medicine to the Dean of the Faculty of Medicine of the University of Bonn which this university had awarded him in 1868. He writes:

Today,  the sight of this parchment is odious to me, and I feel offended to see my name with the title of Virum Clarissimum of which it is adorned, placed under the auspices of a name dedicated to the loathing of my country, the one of Rex Guilelmus... I obey a call of conscience in requesting you to erase my name from the archives of your faculty and to take back this diploma as a sign of indignation which the barbarism and hypocrisy instills in a French scientist from those who, to satisfy a criminal need, insist on the massacre of two great nations.

Pasteur received the following response from the dean:

Sir, the undersigned, the present Dean of the Faculty of Medicine of the University of Bonn, is charged to answer the insult which you have dared to make to the German nation in the sacred person of its noble emperor, the king, William of Prussia, in sending you the expression of all his contempt!  (Signed  Dr. Maurice Naumann.)

Pasteur wasn’t able to restrain himself from replying:

I have the honor to tell you ... Monsieur the Dean, that it is the time where the expression of contempt, in the mouth of Prussian subjects, is equivalent to a heart truly French, to the Virum Clarissimum which you awarded me a short time ago.

Outside of this opposition of principle, other elements should be seriously considered. We said above that Löffler, as did Koch, asserted that certain of Pasteur's cultures weren't pure. An article by G. Ramon informs us that Chamberland added Bacillus subtilis to the anthrax vaccine supplied to Germany (and this without having advised Pasteur) with the aim of preventing commercial German competition through the reproduction, by subculture of the Pasteur vaccine. Therefore, the German accusation of the impurity of the Pasteur vaccine was not without foundation.

But it is more than probable that the major reason for the animosity between Koch and Pasteur was a profound reciprocal misjudgment of their work. Pasteur didn't read German and should have become accustomed to translate the writings of Koch.  Koch understood French imperfectly and over the years had great difficulty in obtaining the foreign scientific publications.  Metchnikoff underlined the resulting conditions in which Koch worked at Wollstein without a laboratory.  In a letter to Professor Cohn, July 15, 1877, Koch thanks him for sending the bacteriology publications and expresses his regrets of not being able to read Pasteur's writings:

Pasteur's details on his anthrax bacillus are very interesting.  If  I only could study them in the original.

 An unedited document in the Museum of the Pasteur Institute under the number of the inventory 19.648 shows the role that ignorance of their respective languages played in the relations between Koch and Pasteur and throws light on the real reason for the development of their polemic at the Congress of Geneva. It deals with a letter dated September 20, 1925 to Doctor Roux, then director of the Pasteur Institute, by Charles Ruel, former privat docent at the Faculty of Medicine at Geneva. Of the eight page letter we extract the following passages:

Sir and very honored colleague, I recently visited the magnificent Pasteur Museum in Strasbourg and on this occasion, the memory of an incident came back to me which occurred unexpectedly at the Fourth Hygiene and Demographic Congress. The incident was marked by an altercation between Pasteur and Doctor Koch of Berlin of which the true cause is known today … What strange thing happened at the Congress of Geneva?  How to explain Pasteur’s excessive irritability, his impatience and violent language?  Let us see of they were not provoked more by the inopportune questioning than by the aggressive tone and singular attitude of the Berlin scholar. In the course of the remarkable and conscientious presentation, when he listed and commented appropriately and properly to the work of Koch and his School, he referred several times to the German Collected works (Recueil allemand).  Now Koch and his friend Prof. Lichtheim, were sitting side by side; they knew French only imperfectly and both mistook the word pride (orgueil) for collection (recueil).  They felt their self-respect profoundly wounded and interpreted the words German pride as a grave insult.  Immediately Doctor Koch at the instigation of his compatriot got up and tried to interrupt the orator in order to protest the terms which he regarded disrespectful. The assembly, ill at ease and amazed, witnessed this quarrel but without understanding.  I have this explanation from Professor Lichtheim himself, who on returning to Berne the day after the congress, we went to the laboratory of pathological anatomy of the faculty where I worked, but a little confused, the account of their scorn and the admission of their unpleasant and awkward intervention of the day before of the old man.... Such is the basis and the true reason which put the two scientists at odds and made of the September 5th session, a turbulent and agitated one. One can easily imagine that interrupted during his masterly presentation, and understanding nothing of the noisy and out of place challenge of Doctor Koch, the orator allowed himself some involuntary movements of impatience and even of anger. Let my evidence bring on a new day the history of this famous session in restoring to Pasteur although tardily, the justice which is due him, to erase forever a stain capable of tarnishing, so little as it is, the glory of the great French scientist.

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