Claude Bernard

French physiologist

• Born: July 12, 1813
• Birthplace: Saint-Julien, France
• Died: February 10, 1878
• Place of death: Paris, France

Bernard has been dubbed the “Father of Physiology,” for developing the experimental methods and conceptual framework needed to change physiology from a primarily deductive science based on statistics to one that can discover empirical data using procedures borrowed from chemistry.

Early Life

The parents of Claude Bernard (behr-nar) were vineyard workers, and Bernard retained a lifelong attachment to the vineyards, returning there each fall to relax and help with the grape harvest and, later, to make his own wine. In the fields of his boyhood, he learned to observe nature and developed the manual dexterity and precision necessary for both wine making and scientific research. His father apparently died while Bernard was still a youth, though little is known concerning him. It is known, however, that Bernard adored his pious mother.

Bernard’s early schooling was in the Jesuit school at Villefranche and later at the Collège de Thoissey, where he studied the humanities but little science or philosophy. When he finished this education, he became a pharmacy apprentice and during his evenings attended the theater and wrote a light comedy, La Rose du Rhône, and a five-act drama, Arthur de Bretagne (1887). His goal of becoming a playwright was shattered when the well-known literary critic Saint-Marc Girardin judged his drama as lacking merit and the author as without literary promise. The critic urged him to study medicine instead.

Bernard entered medical school in 1834 but divided his time between attending lectures and studying and giving lessons at a girls’ school to help his mother pay the bills. His grades were only average, and when he took the internship examination in 1839, he ranked twenty-sixth out of twenty-nine. He began his internship, which was split between two hospitals.

At one of the hospitals, the Hôtel Dieu, Bernard became an unpaid assistant to a clinician and professor of physiology at the Collège de France, François Magendie. This experience had a life-changing effect on Bernard, for Magendie was an outspoken devotee of both experimentation and skepticism. Magendie recognized Bernard’s talents in the laboratory and in 1841 hired him as an assistant on several projects. Bernard was granted his medical degree on December 7, 1843, on the basis of his thesis, Du suc gastrique et de son rôle dans la nutrition (1843; gastric juice and its role in metabolism). Earlier the same year, his first publication had appeared, Recherches anatomiques et physiologiques sur la corde du tympan, pour servir à l’histoire de l’hémiplegie faciale (1843; anatomical and physiological research on the chorda tympani).

In 1844, Bernard failed the examination for a teaching position with the faculty of medicine. Disheartened, he resigned his position with Magendie and considered becoming a country doctor in his home village. A colleague suggested that he find a wife with a good dowry instead, and in July, 1845, he married the daughter of a Parisian doctor. His marriage to Marie Françoise Martin was a matter of financial convenience, allowing him to continue his research, but it was also to be the source of much unhappiness in the years ahead. His wife obtained a legal separation from him in 1870, partly because of her opposition to his vivisectionist experiments. Both sons born to the marriage died in infancy, and the two daughters, like their mother, renounced him and apparently refused to be reconciled with him even on his deathbed.

Between 1843 and 1845, he made discoveries on the chemical and nerve control of the gastric juices and on the role of bile and began experiments with curare and on the innervation of the vocal cords and the functions of the cranial nerves. With the money from the dowry, he was able to continue this research as well as initiate others, and he published a number of papers on various subjects through the mid-1840’s.

Life’s Work

The year 1848 is generally taken to be the year from which Bernard’s mature work dates. In December, 1847, he became an assistant to Magendie at the Collège de France, and the following year began teaching the course on experimental medicine during the winter terms. He also became a charter member and the first vice president of the Société de Biologie, which indicates his growing stature within the scientific community.

In 1848, Bernard’s research led him to two discoveries that were to provide not only new facts but also new ways of conceptualizing bodily functions. First, in his observations on the differences between the urine of carnivores and herbivores, he discovered the part played by the pancreas in the digestion of fats. He published the results of this discovery in Du suc pancréatique, et de son rôle dans les phénomènes de la digestion (1848; pancreatic juice and its role in the phenomena of digestion). Second, he discovered the glycogenous function of the liver. Formerly it was believed that the body could not produce sugars and was therefore dependent upon plants for their source. Bernard’s discovery explained the constancy of sugar in the body and was instrumental in leading Bernard to a concept, which he first articulated during the late 1850’s, of milieu intérieur, or internal environment.

Between the time that he first described this condition of a constant interior environment and his death, Bernard developed and extended the idea until it became the generalized and widely accepted biological notion of homeostasis. In his last comments about it, published in 1878, he explained that the organism does not exist in the milieu extérieur (the external environment of air or water) but rather in a liquid milieu intérieur, which is made of all the intracellular liquids of the organism. These liquids are the bases of all forms of cellular metabolism and the common factor of all simple chemical or physiological exchanges. The body’s task is to maintain the stability of the milieu intérieur; hence, the task of the physiologist is to discover how this regulation occurs.

Bernard’s work during the 1850’s and 1860’s was directed precisely to this task. In 1851, he discovered the control of local skin temperature by sympathetic nerves, and later he showed the importance of the nervous system in regulating the vascular system. In 1856, he demonstrated that curare blocks motor nerve endings, and the following year he reported that the toxic effect of carbon monoxide resulted from blocked respiration in the erythrocytes. He was finally able to isolate glycogen in a pure form in 1857.

Bernard started teaching during the early 1850’s, and in his lectures he argued against vitalism in favor of what he called experimental determinism. He contended that the laws governing the functioning of the organism were precise and rigorous, with the laws of physics and chemistry being fundamental for understanding living phenomena. By varying conditions, the experimental biologists could make the organism respond in a strictly determined manner.

In 1865, Bernard had more time to work on his philosophical ideas, for he became too ill to teach or to conduct research. He retired to the vineyards and wrote his most famous work, Introduction à l’étude de la médecine expérimentale (1865; An Introduction to the Study of Experimental Medicine , 1927), which for many years was his only work translated into English. In this work, he showed his indebtedness to his mentor, Magendie, and to Auguste Comte’s positivism; both stressed the necessity of making observations and determining facts from the evidence. Bernard was unwilling to be shackled by their strict Baconianism, and, against current opinion, he argued that the forming of hypotheses was an essential and necessary part of the scientific process.

The following year, the minister of public education asked Bernard to prepare a report on the state of physiology in France to be published on the occasion of the World Exposition of 1867. Instead of the objective, factual, historical report that was commissioned, Bernard wrote an ideological tract that continued his philosophical thinking. In his Rapport sur les progrès et la marche de la physiologie générale en France (1867; report on the progress and course of general physiology in France), he described his vision of a new brand of physiology founded on the concept of the milieu intérieur and the elucidation of regulatory functions. This report demonstrated what Bernard hoped physiology would become—not what it was.

In later years, Bernard continued to pursue his interests in the phenomena characteristic of all living organisms. He had begun to explore this issue in his lessons at the Sorbonne in 1864, and, when offered the chair of comparative physiology at the Musée d’Histoire Naturelle in 1868, he insisted that the chair be renamed “general physiology.” This willingness to treat general biological problems instead of strictly medical ones not only restructured the way in which questions about living material, life processes, and the properties of living beings were framed and studied but also freed physiology from its subservience to medicine and established it as an independent discipline.

In 1869, Bernard returned to his teaching duties at the Collège de France. He attracted a large and diverse audience, including, at times, Louis Pasteur, and entertained them with demonstrations to support both his physiological and philosophical views. Bernard’s ideas were publicized through ten works, the best known being Leçons sur les propriétés des tissus vivants (1866; lessons on the properties of living tissues) and Leçons sur les phénomènes de la vie communs aux animaux et aux végétaux (1878-1879; lessons on the phenomena of life common to animals and plants).

Significance

The painting Claude Bernard’s Lesson in the Laboratory by Léon Lhermitte delineates one of the most important aspects of Claude Bernard’s work—his teaching and mentoring of younger scientists. In this picture, Bernard, with dark hair and eyes, is dressed in a white gardener’s apron and wears a metal pince-nez around his neck. Near him are several of his disciples, including the electrophysiologist Arsène d’Arsonval; Bernard’s most famous student, Paul Bert; and Louis Ranvier, the founder of histophysiology. Not all of Bernard’s students agreed with him, but the discussions furthered the understanding of science in general and physiology in particular. As a teacher, Bernard ensured the continuation and independence of the new discipline of physiology.

During his lifetime, Bernard showed that general biological laws could be derived from specific experimental data; incorporated the latest techniques and findings of physics and chemistry into biology; developed the concepts of homeostasis, internal secretions, and organismic self-regulation; demonstrated the unity between physiology and medicine; and provided a philosophical basis for experimental biology. These contributions defined modern physiology, and current work in regulatory biology and much neurophysiology is the outgrowth of Bernard’s scientific and philosophical initiatives.

In recognition of his work and status, he was given a chair in physiology at the University of Paris in 1854 and elected to the Academy of Medicine in 1861. In 1867, he was made a commander of the Legion of Honor and served as president of the Société de Biologie. In 1868, he was elected to the Académie Française and served as its president in 1869. In 1870, he was appointed to the senate by Napoleon III and barely escaped from Paris before the Prussian army arrived.

After his illness-enforced retirement in 1865, Bernard never fully recovered his health, although he was able to do some teaching and research. His mind was ever active, and it is reported in many sources that as he grew older, he repeated more and more often, “My mind abounds with things I want to finish.” He became seriously ill in early January, 1878, and died on February 10, 1878, probably of kidney disease. He was the first scientist upon whom France bestowed the honor of a public funeral.

Bibliography

Bernard, Claude. An Introduction to the Study of Experimental Medicine. Translated by Henry Copley Green. New York: Dover, 1957. This classic by Bernard has been widely read. Bernard’s purpose in writing it was to describe the basic principles of scientific research and to outline and explain his philosophy of science. For a philosophical treatise, this book is remarkably clear and easy to follow.

Coleman, William, and Frederic L. Holmes, eds. The Investigative Enterprise: Experimental Physiology in Nineteenth-Century Medicine. Berkeley: University of California Press, 1988. Collection of essays about the development of experimental physiology, including an essay about discoveries in nineteenth century France.

Hall, Thomas S. Ideas of Life and Matter, 600 B.C. to A.D. 1900. Vol 2. Chicago: University of Chicago Press, 1969. Hall succinctly describes Bernard’s answer to four questions: How is the organism constituted? What part or parts of it appear to be alive? By what sign does one recognize “living”? and What does “life” mean?

Holmes, Frederic L. Claude Bernard and Animal Chemistry: The Emergence of a Scientist. Cambridge, Mass.: Harvard University Press, 1974. This work focuses on Bernard’s early research period (1842-1848), when he began to develop his views on experimentation, which would lead him to discover the role and function of the liver. Holmes also describes the scientific environment within which Bernard worked to provide a context for his thought and activities.

‗‗‗‗‗‗‗. “Claude Bernard, the Milieu Intérieur, and Regulatory Physiology.” History and Philosophy of the Life Sciences 8 (1986): 3-25. Holmes explains the intellectual context in which Bernard developed the concept of milieu intérieur and shows how twentieth century physiologists have reinterpreted Bernard’s original ideas to fit the concept of homeostasis. This article demonstrates the problems involved in understanding a scientist-philosopher in his own period instead of trying to make him say what is currently believed to be true.

Lesch, John E. Science and Medicine in France: The Emergence of Experimental Physiology, 1790-1955. Cambridge, Mass.: Harvard University Press, 1984. Surveys the development of experimental physiology and its impact on science and medicine in France.

Olmsted, J. M. D. Claude Bernard: Physiologist. New York: Harper & Row, 1938. This is probably the best-known biography of Bernard and is very good despite the pre-World War II date of publication.

Roll-Hansen, Nils. “Critical Teleology: Immanuel Kant and Claude Bernard on the Limitations of Experimental Biology.” Journal of the History of Biology 9 (Spring, 1979): 55-91. Kant and Bernard proposed similar methodologies for biology. This article examines those methodologies, compares them, and shows how Kant’s program had ethical and moral implications, while Bernard’s approach was related to questions of science policy. The article describes the similarities and differences between Bernard and many of the natural historians and physicians of his period.