A TOUCH OF FRANCE: Claude Bernard (1813-1878) and experimental medicine “Physiology, physiology, it’s in me…”

Claude Bernard (1813-1878)
and experimental medicine
“Physiology, physiology, it’s in me…”
C. Régnier, France

La leçon de Claude Bernard by Léon Lhermitte shows Bernard with his pupils in his Collège de France laboratory.

© Wellcome Library, London.

The Théâtre des Champs-Elysées: the venue that launched a masterpiece
D. Marsh, France

Every year some 300 000 people come to the Théâtre des Champs-Élysées in Paris for concerts and
recitals in the main auditorium, plays at the Comédie, and exhibitions in the Studio.

© Bertrand Rindoff
Petroff/Getty Images.

Christian RÉGNIER, MD
Pierre and Marie Curie University
(UPMC – Paris 6)
International Society for the History of Medicine (ISHM) 9 rue Bachaumont 75002 Paris
(e-mail: dr.christian.regnier@wanadoo.fr)

Claude Bernard (1813-1878)
and experimental medicine
“Physiology, physiology, it’s in me…”
by C. Régnier, France

As a pioneer of modern physiology, then as a philosopher who laid the foundations of the experimental method in medicine, Claude Bernard (1813-1878) is an emblematic figure in French science of the mid-19th century. His method, discoveries, and vocabulary left a lasting mark on medicine. He worked on a range of topics in parallel between 1844 and 1865: hepatic glycogenesis, nutrition and pancreatic secretion, the effects of curare, gas exchange in red blood cells, and sensory and motor innervation. This colossal undertaking had but a single aim: to define the concept of the milieu intérieur (‘environment within’) that subtends all animal or plant life. Pasteur, who concentrated on much more practical research topics, was his ardent supporter. In 1865, he was one of the few scientists to offer an enthusiastic welcome to the publication of Claude Bernard’s Introduction to the study of experimental medicine, a philosophical manifesto on medical research and the conditions subtending life. Yet the two scientists fell out around 1877 over conflicting interpretations of anaerobic alcoholic fermentation. Claude Bernard was the first French scientist to receive a State funeral. On February 16, 1878, after the service in the church of Saint-Séverin, 4000 mourners followed the cortege to Père Lachaise cemetery. Republicans lost no time in claiming this agnostic Second Empire senator as their own, thus marking the entry of modern science into the political arena: politicians transposed to the social sciences the experimental method that Claude Bernard had applied to medicine.

Medicographia. 2013;35:474-484 (see French abstract on page 484)

To use a word which he himself introduced into the vocabulary of French science, nothing “determined” Claude Bernard to become a doctor, an experimenter of genius, a pioneer of modern physiology, and a man of whom a former student, the physiologist and politician Paul Bert (1833-1886), recalled: “He made discoveries the way that others breathe. With grace and good faith. It was his cardinal quality. In everything he did he showed the same deep sincerity of the scientist in search of the truth for its own sake and for the sake of the truths that follow.”1

Born on July 12, 1813 into a family of winemakers in Saint Julien en Beaujolais, near Villefranche sur Saône (department of the Rhône), Claude Bernard learned Latin, Greek, geometry, and arithmetic from the fathers in the diocesan school, but did not sit the baccalaureate. He was imbued with Cartesian philosophy and the Romantic movement.

Photographic portrait of Claude Bernard (1813-1878) by
Guillemet. Musée Claude Bernard. © Coll. BIU Santé (Paris).

At 19, he was taken on as an assistant by a pharmacist in nearby Vaise, and began delivering some of his preparations to the School of Veterinary Medicine in Lyon. This introduced him to their laboratories, operating rooms, and animal houses. He stayed with the pharmacist for 19 months, at which point his apprenticeship was abruptly terminated after he made a mistake in one of his concoctions.2,3 After tasting fleeting success with several performances of his vaudeville La rose du Rhône in a Lyon theater, he came to Paris in November 1834 to deliver a newly-completed historical romance, Arthur de Bretagne, to Saint-Marc Girardin (1801-1873), a member of Parliament, professor of literature at the Sorbonne, and theater critic. Legend has it that this illustrious figure advised him: “You have a background in pharmacy, young man. Why not study medicine? You could do better writing scientific articles. Keep literature for relaxation.”2-4

Claude Bernard acted on this advice without further ado. After passing an Arts baccalaureate, he enrolled in the Paris Faculty of Medicine in November 1834, qualifying as a junior resident five years later, although only 26th out of 29. On December 7, 1843, he defended his doctoral thesis Gastric juice and its role in nutrition, only to fail the university lecturer examination, the agrégation, the following year. He made friends during his student years with the future psychiatrist Ernest- Charles Lasègue (1816-1883), and the pioneering bacteriologist and microbiologist Casimir Davaine (1812-1882).3,5

In the footsteps of the master, François Magendie

Claude Bernard spent most of his residency at the since demolished La Charité hospital in Paris under Alfred Velpeau (1795-1867) in surgery and Pierre Rayer (1793-1867) in medicine. Rayer took him under his wing, introducing him to the positivist Émile Littré. Future physician to Napoleon III (1808- 1873), Rayer’s interests were in kidney disease, diabetes, and dermatology; he was impressed by the young doctor’s powers of deduction. Claude Bernard also did residencies at the Hôtel-Dieu under the surgeon Jacques Gilles Maisonneuve (1809-1897) and at the Salpêtrière under the psychiatrist Pierre Falret (1794-1870).3,5

By pure chance, in 1841 at the Hôtel-Dieu, he came under François Magendie (1783-1855), for whom the chair in experimental medicine had been established at the Collège de France ten years previously. A former surgeon, Magendie had published multiple papers on experimental physiology between 1809 and 1816, including the celebrated Elementary compendium of physiology, which for long had been a standard work in the field. As a member of the Academy of Sciences since 1821, he had founded the first French physiology journal, the Journal de physiologie expérimentale et pathologique (which folded in 1831). Magendie described the mo- tor function of the ventral spinal nerve roots and provided a partial explanation of the sensorimotor reflex. He also studied the mechanism of action of strychnine using methods that heralded modern pharmacology.

The house in which Claude Bernard was born,
in Saint Julien en Beaujolais (department of the
Rhône, France). Photo taken in 1931. Born into a
family of winemakers, Bernard learned Latin,
Greek, geometry, and arithmetic at the local
diocesan school.
© Coll. Académie Nationale de Médecine.

Having noted Claude Bernard’s skill with the scalpel (so the legend goes), Magendie appointed him as his assistant from 1841 to December 1844; he taught him the discipline required to conduct experiments using live animals, introduced him to vivisection, and trained him in the critical appraisal of scientific dogmas and systems. Master and pupil worked together on neurophysiology, cerebrospinal fluid, thermoregulation, and pharmacology.3,5,6

19th century French School painting of François Magendie.
Oil on canvas. Magendie is considered as a pioneer of modern experimental
physiology. © Bibliothèque de l’Académie Nationale de Médecine.

In 1844, after failing the agrégation, Claude Bernard experienced a period of doubt compounded by disagreement with his mentor, who shut him out of the laboratory. Magendie accused him of privileging theory at the expense of practice. Claude Bernard was also having financial problems conducting his own research in his laboratory in the Cour Saint André des Arts. Rayer found him some additional income preparing dissections for the lithographer Jacob who was illustrating Bourgery’s celebrated Anatomical Atlas.

In 1845, with his friend Lasègue, he opened a laboratory and private physiology school which closed fairly quickly due to a lack of students. In May of the same year, he married Marie Françoise Martin, the financially well-endowed daughter of a Paris physician, putting money troubles behind him. After patching up the relationship with Magendie (thanks to peacemaking by Rayer), he stood in for him at the Collège de France in 1847, teaching the winter semester. Magendie then transferred his laboratory and chair to him from 1852; Claude Bernard became his official successor on Magendie’s death in 1855.3,5,6

In his inaugural lecture on February 29, 1856, Claude Bernard paid tribute to his departed mentor: “Mr Magendie felt a truly extraordinary repulsion towards thinking in systems […] His predominant idea was to fix the experimental method in medicine and physiology once and for all […] When people said to him: ‘According to such and such a law, things should happen in such and such a way’ or ‘Analogy shows that events will follow such and such a course’, he’d reply: ‘I have no idea; conduct an experiment and tell me what you find.’ ‘Conduct an experiment’ was his stock answer for forty years to all questions of this kind. […] He only said what his eyes had seen, and he would wait for other experiments and experiences to supply new items of evidence that might solve the problem […] So finally, gentlemen, you can see that although science has had the misfortune to lose Mr Magendie, he remains with us in spirit and the method we received from him is what continues to guide us today.”7

Claude Bernard was always attached to the style of teaching dispensed at the Collège de France, describing it as being directed at science in the making rather than at science made: “It must always reflect the state of the art in medical science,” in contrast to the teaching dispensed in the faculties which he characterized as based on the acquisitions of the past.

Claude Bernard was an indifferent public speaker but he interspersed his lectures with impromptu experiments, attracting a large audience from around the world, some of whom became his disciples: Arsène d’Arsonval, Paul Bert, Albert Dastre, Louis Gréhant, Willy Kühne, Élie de Cyon, Louis Ranvier, Ivan Setchenov, Angelo Mosso, Edmé Vulpian, Louis Charles Malassez, Peter Ludwig, Benjamin Ball, Austin Flint, and William Horner.3,5,6

Skills and methods

Claude Bernard conducted his experiments in the modest laboratory of the Collège de France (known as “the cellar”), at the Sorbonne, in the National Museum of Natural History, at the School of Veterinary Medicine in Maisons-Alfort, and in slaughterhouses. His friend Ernest Renan (1823-1892), who held the Hebrew chair at the Collège de France, recalled: “It was a striking spectacle to see him in his laboratory, thoughtful, sad, absorbed, totally focused, and unsmiling. He felt he was doing sacred work, celebrating a kind of sacrifice. His long fingers delved into the wounds like those of an augur in Antiquity, chasing mysterious secrets within the entrails of victims.”

Renan took over Claude Bernard’s chair at the French Academy. The practice of vivisection earned the physiologist the profound disapproval of many detractors, in particular his own wife and two daughters who joined anti-vivisectionist leagues such as the Animal Protection Society (registered as being of public utility in 1866).8

Collège de France
Bernard attended
François Magendie’s
courses here and
himself became a
professor at the
Collège de France
in 1853. Photomechanical
Maison parisienne
Berthaud frères.
© Coll. BIU Santé (Paris).

La leçon de Claude Bernard by Léon Lhermitte shows Bernard with his pupils in his Collège de France laboratory. © Wellcome Library, London.

Bernard had a solid grounding in anatomy, “a simpler science than physiology, and one which thus should be subordinate to it, rather than dominate it. Any explanation of the phenomena of life based exclusively on anatomical considerations is necessarily incomplete.” He had no time for “vitalism”, a theory still in vogue at the start of the 19th century which held that the phenomena of life were subject not to the laws of physics and chemistry but to a “vital force” emanating from living tissues. Yet he admired the work of Xavier Bichat (1771-1802), “the greatest anatomist of the modern era,” without sharing the vitalist theories contained in his Treatise on membranes (on tissue anatomy) published in 1800.7,9

Illustrated Anatomical Atlas. By Jean-Marc Bourgery and Claude
Bernard, and the anatomist and artist Nicolas-Henri Jacob.
Anterior view of the superficial muscles of the trunk.
© Coll. BIU Santé (Paris).

Bernard was an excellent chemist. He admired the discoveries made by Antoine Laurent de Lavoisier (1743-1794) and Pierre de Laplace (1749-1827). He worked with the chemist Charles Barres will (1817-1870) in the laboratory of Théophile- Jules Pelouze (1807-1867) in rue Dauphine. He also studied the biochemistry of fats with his chemist friend Marcellin Berthelot (1827-1907). In his doctoral thesis (1843) on the role of gastric juice in digestion, he used his chemistry training to measure fasting and postprandial gastric acidity.5,10

Unlike the German physiologists, he made little use of measuring instruments to quantify the phenomena of life; he even criticized German physiology for too often being reducible to a series of physicochemical reactions. The Germans reciprocated by considering Claude Bernard an impulsive and romantic experimentalist over inclined to generalization. He also made little use of the microscope, on the grounds that it “narrowed the mind.” In the Red notebook where he entered his more private thoughts, he wrote: “An excess of microscopy does a disservice to physiology. It ends up making everything the same, leaving us with effects without causes.” This accounts for his reservations over the cell pathology research by Rudolf Virchow (1821-1902) that failed to take cell chemistry reactions into account.1,5,10

While acknowledging the contribution of mathematics and statistics in establishing quantitative demonstrations, Bernard issued this warning to fellow experimentalists: “It is not that I wish to outlaw the application of mathematics to biological phenomena, since this ultimately is where the future of the science lies; but my conviction is simply that a general equation is impossible for the moment: the qualitative study of phenomena must necessarily precede their quantitative study.”4,8,9,11

Claude Bernard made daily jottings of his observations, thoughts, and comments, together with lecture and reading notes, on the most varied of materials, mostly backs of envelopes, loose sheets of paper, and little notebooks. Archived in the Collège de France, Academy of Sciences, Academy of Medicine and the Claude Bernard Museum in Saint Julien en Beaujolais, this scattered material was assembled and classified in the late ’60s by Mirko D. Grmek, who tracked and unraveled the innermost thoughts and intellectual trajectory— marked by failure, frustration, and success—of a man in search of truth.

Determined to pursue his research in the absence of any preconceived ideas and to keep his mind entirely free, Claude Bernard worked on several fronts simultaneously. Comparing and contrasting his experiences and experiments, he was always reworking his notes and observations in the conviction that knowledge constantly progressed and evolved over time. The thread running through all his experiments and discoveries was his drive to understand the milieu intérieur, or environment within.10,12

Color lithograph of the pancreas by Borromée and Lackerbauer
from Claude Bernard’s 1859 paper on the pancreas and
the role of pancreatic juice in digestion.
© Coll. BIU Santé (Paris).

Marcellin Berthelot in his laboratory. Wood engraving by Guth
and Florian. Claude Bernard’s notes on alcoholic fermentation
were published five months after his death by Berthelot.
© Coll. BIU Santé (Paris).

Main research interests:5,10,11,13
Glycogenesis (1843-1857). His research on “animal glycogenesis” began with the famous “liver wash-out” experiment (1855). Later, with Charles Barres will, he chemically identified glycogen as the precursor of glucose. His doctor of science thesis on hepatic glycogenesis (1853) paved the way for enzymology.
Nutrition (1843-1860). The publication in 1859 of his Report on the pancreas and the role of pancreatic juice in digestion marked the first stage of his studies in nutrition. He discovered the function of bile in protein digestion and in 1860 published his Lectures and physiological experiments on nutrition.
Mechanism of action of curare and strychnine (1843-1853). “Curare simply interrupts something motor that creates an electrical connection between muscle and nerve through movement.” Claude Bernard predicted the existence and role of the motor plate but could not prove it experimentally. However, he was wrong about the site of action of curare, locating it at the distal extremity of the motor nerve.
Carbon monoxide poisoning and the mechanisms of oxygen- carbon dioxide exchange (1846-1856). He explained the role of red blood cells in respiration, showing that oxygen bound to hemoglobin: “These respiratory elements circulate with the blood and alternately absorb oxygen on contact with air, at the lung surface, then transport it into the depths of the milieu intérieur, in contact with the fixed histological elements of living tissues.”
Nervous system (1844-1858). In addition to his unfinished studies on the anatomy and physiology of the chorda tympani, he described in particular the role of vagal inhibition of the heart, and the vasoconstrictor and vasodilator nerves of the sympathetic system. In 1858, he published his Lectures on the physiology and pathology of the nervous system.

The milieu intérieur concept was his major work. He built it brick by brick between 1851 and 1878. He expounded the concept in December 1857: “Physiologic phenomena in higher organisms take place in organic and highly perfected milieux intérieurs possessing balanced physicochemical properties.” The milieu intérieur regulates blood acidity and body temperature, adjusting them to changes external to the body. “The milieu intérieur has to be liquid because water is essential for chemical reactions and for displaying the properties of living matter.” In studying the vectors of cell interaction (although without developing the concept of remote-acting hormones), he expounded the concept of “internal secretion,” namely an organ’s ability to secrete a substance and release it directly into the bloodstream. The French philosopher Georges Canguilhem (1904-1995) pronounced the milieu intérieur concept as having constituted a sort of “Copernican revolution.” 5,10,11,14

1865: The experimentalist mutates into
a philosopher

On December 30, 1913 at the Collège de France on the centenary of Claude Bernard’s birth, the philosopher Henri Bergson (1859-1941) declared: “The Introduction to the study of experimental medicine is for us a little like what the Discours de la méthode was for both the 17th and 18th centuries. In each case we find ourselves in the presence of a genius who began by making great discoveries and then wondered how one had to proceed in order to have done so: although paradoxical in appearance, this is the only natural order of events, since the reverse order has been attempted much more often and has never succeeded.”15

The issue of philosophy in medico-scientific experimentation was far from an academic abstraction for Claude Bernard: it was the direct result of the questions and doubts that assailed him on achieving experimental results that overthrew conventional scientific thinking. “There comes a time in one’s scientific career when it is good to collect one’s thoughts, take stock and ask where one has arrived and where one is heading,” he wrote in his Principles of experimental medicine. “I believe this to be particularly useful when studying a science as complex, obscure, and poorly defined as medicine.”

Physiology in the hands of Claude Bernard was not just a branch of anatomy, physics, or chemistry; it involved the development of multiple temporary hypotheses that were reworked in the light of experimentation and the responses of the live animal. Claude Bernard also set physiology apart from the empiricism of medicine by endowing it with its own concepts developed through specific methods of investigation.10,11

The principles of Bernard’s philosophy can be found in notes, lectures, and several of his publications throughout his life, the best known being the Introduction to the study of experimental medicine published in 1865, written when resting and convalescing at his house in Saint Julien en Beaujolais, bought in 1861. One year previously, he had experienced the first symptoms of colitis, together with migraine and joint pain, diagnosed by Rayer and Davaine as a “a chronic form of cholera.” It was during one of these stays that he read, criticized and was inspired by the work of Auguste Comte (1798- 1857), the founder of positivism. “Comte’s idea of considering positivist philosophy in terms of scientific generalities is wrong. It is absolutely essential to get down to the details.”

Paul Bert by Mascre-Souville. Oil on canvas, 58×48 cm.
A brilliant student of Claude Bernard, physiologist, and politician,
Paul Bert was elected to the Académie des Sciences in 1882.
© RMN-Grand Palais/Droits réservés.

Jacques Arsène d’Arsonval, member of the Institut de France in
his biological physics laboratory at the École des Hautes Études.
Maison parisienne Neurdein. © Coll. BIU Santé (Paris).

The Introduction was the first chapter in Claude Bernard’s major contribution to philosophy (it remains part of the philosophy baccalaureate curriculum). As well as in the notes contained in the Red notebook and Principles of experimental medicine (collated and published in 1947 by Léon Delhoume), he developed his philosophical ides in his Lectures on the phenomena of life common to animals and plants, published posthumously in 1878-1879, in which he insisted on the fundamental unity between the two worlds.

s for his 1867 Report on the progress and practice of general physiology in France, this was more political, in that it was commissioned by Victor Duruy (1811-1894), minister of public education, in preparation for the Third Universal Exhibition to be held in Paris the same year. It was Napoleon III’s intention to use the Exhibition to showcase French science, in direct competition with science in German-speaking countries where heavy investment and decentralized organization had produced remarkably effective results.

Already esteemed by the Emperor and his wife—in 1864 they had invited him to spend a week at the Château de Compiègne— Claude Bernard wrote in the report that “general physiology” should be established as a science in its own right and receive the same level of State funding as that earmarked for “the long-established sciences securely positioned within the social fabric.”2,4,10,11,13,16

The Introduction to the study of experimental medicine received a lukewarm welcome from physicians both in France and abroad; physiology journals ignored it on the grounds that its subject matter fell outside their scientific purview. Yet the book was a more than positive report on over 20 years of successful research rewarded by its author’s appointment to the Faculty of Sciences and Collège de France. The book was not translated into English until 1927, into Spanish in 1936, and into German in 1961.

Claude Bernard invented “determinism,” a word that he introduced into French. “The primordial principle in the basic sciences is determinism. […] All vital phenomena, whatever they may be, are subject to strict determinism, and this determinism cannot possibly be anything other than physicochemical determinism. […] Determinism is everything. It is inescapable. […] We must take it as an experimental axiom that in living beings as much as in inanimate matter, absolute determinism governs the conditions under which every phenomenon exists. This means, in other words, that once the condition for a phenomenon is known and met, the phenomenon should always recur necessarily, at the experimenter’s command. To deny this would amount to nothing less than denying science itself.” This principle influenced future generations of scientists: an experiment must be reproducible in order to be validated.4,5,8,9,11

Introduction to the Study of Experimental Medicine
by Claude Bernard, published by Baillière, Paris 1865.
© Wellcome Images.

Maintaining that scientific truth is objective and demonstrable, not revealed or imposed, and that phenomena must always be approached with the question “how” rather than “why,” Claude Bernard based his “method” on three cardinal principles: observation, experimentation, and deductive reasoning. Because Nature only allows a limited number of facts to be observed, these need to be prolonged or evoked by experiment. By combining with chemistry, physics, and all the exact sciences, physiology becomes able to be explain all living phenomena, whether normal or pathological.4,5,8

In wanting hospitals to be equipped with integrated laboratories so that physicians could relate their clinical knowledge to physiologic experimentation, Claude Bernard looked forward to proclaiming the imminent demise of empirical medicine. However, he came up against the hostility of the Academy of Medicine, for whom the primacy of the anatomo-clinical method—another great pride of 19th century French medicine— was sacrosanct.

Claude Bernard versus Louis Pasteur: the issue of modern biology

Already crowned in glory for his at once “patriotic” and practical approach to medicine, Louis Pasteur (1822-1895) was immediately alert to the importance of the Introduction in guiding medical research methodology. An already recognized scientist, Pasteur had attended Claude Bernard’s lectures at the Faculty of Sciences in 1860 and those on “experimental medicine” given in the winter of 1862-1863 at the Collège de France. On November 7, 1806 he published an article in Le Moniteur Universel: “Nothing as clear, complete, and profound has been written on the actual principles behind the supremely difficult art of experimentation. This book is barely known because written at a level that few these days can reach. […] Claude Bernard’s arguments have the same clarity and robustness as the sciences of physics and chemistry.” The day after the article appeared, Claude Bernard replied: “Your work has caused your name to be writ large and it has placed you in the forefront of contemporary experimentalists; I have no better way of saying that the admiration you profess for me is entirely reciprocal. We must have been born to get along together as we are both driven by the same passion and same feelings for true science.”

In 1859, Claude Bernard had written a favorable report to the Academy of Sciences supporting the award of the Montyon prize in experimental physiology to Pasteur for his work on alcoholic fermentation and the isomers of tartaric acid; he had drawn attention to the “physiological bent to his research” and the “experimental skills of this distinguished scientist.” The two leading lights in French 19th century medical research appeared to be working in perfect harmony.4,5,8,17

However, they were to fall out around 1877 when in his Principles of experimental medicine Claude Bernard deplored the fact that “Pasteur follows his ideas and wants to bend the facts accordingly, whereas I follow the facts and aim to coax out the ideas more or less by themselves. Pasteur wants to direct Nature, whereas I let Nature direct me: I follow Nature […] I am Nature’s secretary. Pasteur and the a priorists are out to dictate Nature’s responses to suit their own ideas.” Bernard was skilled at exploiting serendipity starting from hypotheses that were not always correct; Pasteur performed experiments to confirm his intuitions. Pasteur immediately threw back at Claude Bernard the accusation that he was using a system-based approach.

In reality the two men disagreed on the factors and conditions for alcoholic fermentation. Having devoted many years of his life to this question (one of national interest), Pasteur attributed the transformation of sugar into alcohol under anaerobic conditions to the presence of microorganisms. Claude Bernard believed that this chemical transformation depended on soluble “culture agents” (ferments), and not exclusively on living cells, but was unable to demonstrate this experimentally and published nothing on the question in his lifetime. His notes on alcoholic fermentation were published in July 1878 by the chemist Marcellin Berthelot, five months after his death; they aroused the wrath of Pasteur.

The “culture agent” turned out to be an enzyme, zymase, isolated in 1897 by the German scientist Eduard Büchner (1860- 1917). “Pasteur fully acknowledged what discouraged Claude Bernard, who proved the victim of his definitions, beholden despite himself to Lavoisian biochemistry (oxygen as the condition of life) […] It was his respect for Lavoisian dogma that made him unable to accept certain data in physiology […] That is why he preferred to define alcoholization as simple molecular degradation,” wrote the philosopher-physician François Dagognet.5,8,11,17,18

Monument to Claude Bernard in the main square of Saint-Julien
en Beaujolais (department of the Rhône).
© Coll. Académie Nationale de Médecine.

This dispute between the two giants of French science raised the whole question of modern biology. For Claude Bernard, a functioning live organism was an organism that destroyed itself by itself little by little via physicochemical phenomena tending towards death. Pasteur was something of a “vitalist” and thought along different lines, focusing on the external insults that threatened the fine balance of living organisms. As a prisoner of his “determinism” and hence of his “ideas”, Claude Bernard became unable to grasp the full implications of cell pathology and germ theory. The heated debate between the two giants of French science paved the way to modern scientific medicine, with Claude Bernard considering disease as a process disruptive of the milieu intérieur while Pasteur viewed it as an external interference independent of any determination.17,19

1. Bernard C. Cahier de notes 1850-1860 [Notebooks 1850-1860]. Paris, France: Gallimard; 1965.
2. Marduel MA. Claude Bernard – Un physiologiste natif du Beaujolais, sa vie, son oeuvre [Claude Bernard – A Beaujolais physiologist’s life and work]. Paris, France: Société des Gens de Lettres; 2006.
3. Debray-Ritzen P. Claude Bernard ou un nouvel état de l’humaine raison [Claude Bernard or a new state of human reason]. Paris, France: Albin Michel; 1992.
4. Lévy I. Un disciple d’Esculape, Claude Bernard, face à Thalie [A disciple of Asclepius, Claude Bernard, meets Thalia]. Rev Prat. 1996;46(7):795-798.
5. Grmek MD. Le legs de Claude Bernard [The legacy of Claude Bernard]. Paris, France: Fayard; 1997.
6. Holmes FL. Physiology and experimental medicine. In: Grmek MD, Fantini B, eds. Shugaar A, translator. Medical thought from Antiquity to the Middle Ages. Cambridge, MA: Harvard University Press; 2002.
7. Bernard C, Magendie F. Leçon d’ouverture du cours de médecine du Collège de France, 29 février 1856 [Inaugural lecture in medicine at the Collège de France, 29 February, 1856]. Paris, France: J.B. Baillière; 1856.
8. Grmek MD. Raisonnement expérimental et recherches toxicologiques chez Claude Bernard [Claude Bernard’s experimental reasoning and toxicological research]. Geneva, Switzerland: Droz; 1973.
9. Bernard C. An introduction to the study of experimental medicine. Henderson LJ, ed. Greene HC, translator. London, UK: Macmillan & Co Ltd; 1927. Reprinted: New York, NY: Dover Publications Inc; 1957.
10. Prochiantz A. Claude Bernard, la révolution physiologique [Claude Bernard: revolution in physiology]. Paris, France: Presses Universitaires de France; 1990.
11. Bernard C. Principes de médecine expérimentale [Principles of experimental medicine], Paris, France: Presses Universitaires de France; 1947.
12. Michel J, ed. La nécessité de Claude Bernard [The necessity of Claude Bernard]. Paris, France: Méridiens Klincksieck; 1991. Republished: Paris, France: L’Harmattan; 2002.
13. Bernard C. Notes pour le rapport sur les progrès de la physiologie [Notes for the report on the progress of physiology]. Paris, France: Collège de France; 1979.
14. Canguilhem G. The normal and the pathological. Fawcett CR, Cohen RS, translators. New York, NY: Zone Books; 1991.
15. Bergson H. La philosophie de Claude Bernard [The philosophy of Claude Bernard]. Paris, France: Presses Universitaires de France; 2012.
16. Bernard C. Lectures on the phenomena of life common to animals and plants. Hoff HE, Guillemin R, Guillemin L, translators. Springfield, IL: Thomas; 1974.
17. Michel J. Le différend Pasteur/Bernard: un débat de clôture pour la biologie du XIXème siècle? [The Pasteur/Bernard dispute: a closing debate on 19th century biology?]. In: Donzelli M, ed. La biologia: parametro epistemologico del XIX secolo. Naples, Italy: Liguori Editore; 2003.
18. Dagognet F. Méthodes et doctrines dans l’oeuvre de Pasteur. [Methods and doctrines in the work of Pasteur]. Paris, France: Presses Universitaires de France; 1967.
19. Sinding C. Le clinicien et le chercheur: des grandes maladies de carence à la médecine moléculaire [Clinician and research scientist: from the great deficiency diseases to molecular medicine]. Paris, France: Presses Universitaires de France; 1991.