See also figure 8.3.
Figure 8.3
An unlabeled sketch from Bernard’s Cahier Rouge, a diary in which he wrote (1850–1860) about not only things he had seen in the laboratory that day and the experiments or hypotheses that these had suggested, but also his constant search to express the experimental method in physiology, and to show how it related to other sciences (Bernard, 1967). The sketch seems to be a device for measuring the temperature in the two ears of a rabbit, presumably for an experiment like the one shown in figure 8.2.
Bernard was a consistent opponent of vitalism, arguing that biology never violated the laws of physics and chemistry. However, he did stress the emergent properties of complex biological systems much more than his German physiological contemporaries such as Helmholtz and du Bois-Reymond, who strove to reduce biological phenomena to physics and chemistry.8
The high point of Bernard’s theoretical endeavors was the publication in 1865 of his Introduction to the Experimental Study of Medicine. It was an immediate success among scientists and physicians as well as philosophers and writers. Indeed, it remains in print to this day, even in English, and is still heralded as required reading for any prospective experimental biologist. One of its most timeless and attractive aspects is its autobiographical character; Bernard illustrates various principles and practices of experimentation almost exclusively from his own work. He does clean up the stories of some of his discoveries, however, omitting errors, blind alleys, and failed experiments.9 Thus the book makes science seem easier than it really is.
MME. BERNARD AND MME. RAFFALOVICH
In 1845, near the beginning of his career, financial difficulties led Bernard into an arranged marriage with Fanny Martin, the daughter of a relatively well-off physician. Her dowry enabled him to avoid a rural practice and stay in research. The marriage was a disaster. Mme. Bernard bitterly resented her husband’s low-paying research career and became an ardent antivivisectionist. Bernard’s propensity to bring home opened-up and dying animals with various tubes stuck in them did not help matters. Finally, in 1869, when Bernard reached the peak of his career, they separated. Subsequently, she and her daughters founded a home for stray dogs and cats.10
After the separation, Claude Bernard became close to Marie Raffalovich, a Jewish intellectual from Odessa who was interested in science and philosophy. She attended his lectures, he visited her twice a week, and they often went to galleries and museums together. Unlike Bernard, she was an accomplished linguist and helped him with the foreign literature. Over the course of nine years he wrote over 500 letters to her, often when she was away on holiday with her family. Many of them have been published in two collections, and they yield a fine-grained account of his daily life and thoughts (see box 8.2). In 1876 she published a novel and he claimed that she was deserting him for the literary crowd. Then, in 1878, when she received news that he was very ill, she and her daughter went to nurse him in his final days. Mme. Raffalovich had her letters to Bernard destroyed after his death.11
Box 8.2
From Bernard’s Letters to Mme. Raffalovich
[1870, after a discussion of science, intuition, and superstition] The scientist, if he is to have great ability, must have imagination but he must master this imagination and coldly probe the unknown. However, if he lets himself be carried away by his imagination, he will be overcome by vertigo and, like Faust and others, fall into the chasm of magic and succumb to phantoms of the mind.
[1873, after a description of the history of the College de France] I follow in the tradition of my predecessors, who have all been men in the avant-garde of science, men of fighting spirit. I am fighting for physiology because it is the future of medicine. (Quotations from Bernard, 1978 [1869–1878])
HONORS AND FAME
Claude Bernard collected more honors and, arguably, became more famous than any French scientist before or after. He was elected to the Academy of Science, then the Academy of Medicine, and finally, most prestigious of all, he became one of the 40 “immortals” of the French Academy and eventually its president. He was commander of the Legion d’Honneur and a member of the Senate (a powerless front for the autocracy of Napoleon III). Bernard dutifully attended every Senate meeting but did not speak, even on such issues as academic freedom and rural medicine. When he died he was given the first state funeral ever afforded a scientist in France. Flaubert called it more beautiful and more stirring than the then-recent funeral of Pope Pius IX.12
From the height of his career until well after his death, Bernard was so famous that he became identified in the public mind as the stereotypical scientist, much like Albert Einstein in the twentieth century.13 He appears in poetry, memoirs, and novels of the time, both in France and abroad (e.g., The Brothers Karamazov). Zola considered writing a novel in which a scientist is persecuted by his antivivisectionist wife, and wrote:
I will make a scientist married to a backward bigoted woman, who will destroy his researches as he works. . . . I am tempted to model him after Claude Bernard, getting access to his papers and letters. It will be amusing . . .14
In the completed novel Le docteur Pascal, Zola moved away from Bernard as a model; the plot complications required a heredity researcher rather than a physiologist, but some similarities to Bernard remain. In his essay “The Experimental Novel,” supposedly modeled after Bernard’s experimental medicine, Zola manipulated plots and observed the behavior of his human characters just as Bernard manipulated physiological variables and observed their effects. “I have but one desire,” Zola wrote. “Given a powerful man and an unsated woman, to cast them into a violent drama and scrupulously note down the sensation of these creatures.” In fact this was hyperbole if not outright hype: Zola had begun his novel cycle before he was familiar with Bernard’s writings (and before Bernard was famous).15
A bronze statue of Bernard engaged in vivisection was set up in front of the College de France after his death. The Germans melted it down in World War II and it was replaced by a new statue in stone after the war.16 This was destroyed during the student uprising of 1968 but has subsequently been replaced.
As Bernard had desired, his early play Arthur de Bretagne was published after his death. However, his widow and daughters claimed its preface defamed them and they successfully sued to have all copies destroyed. It had a radio production in 1936, and a second edition appeared in 1943.17
THE CONSTANCY OF THE INTERNAL ENVIRONMENT
Bernard’s ideas about the internal environment evolved from its first mention in 1854 until his death in 1878. He probably took the term from Charles Robin, a contemporary histologist who used milieu de l’interieur as a synonym for “the humors.” Initially, for Bernard, the internal environment was simply the blood. But even at this stage, he understood that the temperature of the blood is actively regulated and that its constancy is particularly critical in higher animals. It was only later that he recognized that this constancy might be achieved through the vasomotor mechanisms he had discovered. At about the same time he realized that the glycogenic mechanism he had found controlled the constancy of blood sugar level. It was primarily on these two (limited) lines of evidence that he built his brilliant generalizations that unify the fundamental physiologies of the body:18
The fixity of the milieu supposes a perfection of the organism such that the external variations are at each instant compensated for and equilibrated. . . . All of the vital mechanisms, however varied they may be, have always one goal, to maintain the uniformity of the conditions of life in the internal environment. . . . The stability of the internal environment is the condition for the free and independent life.19
These generalizations both summarized many of Claude Bernard’s experimental achievements and provided a program for the next 100 years of general physiology. Although Bernard made these ideas central to his well-attended lectures and his widely disseminated writings, they were ignored in his lifetime and they had no impact at all until about 50 years later. Indeed, Be
rnard’s ideas on the internal environment are hardly mentioned in the extensive 1899 biography by Michael Foster, the distinguished Cambridge physiologist; they are not mentioned at all in the twelve-page obituary in the American journal that had published much of Bernard’s research or in a 1931 biographical essay by the eminent historian of science Henry Sigerist. Whereas the 1911 Encyclopedia Britannica is totally silent on the constancy of the internal environment, the 1975 edition calls it Bernard’s “most seminal contribution.”20
An exception to the nineteenth-century silence on Bernard’s internal milieu was George Henry Lewes (1817–1878), the Darwinian publicist (and life partner to George Eliot, in which capacity he made the inside back cover of the New Yorker in 1998). In his The Physical Basis of Mind, Lewes used the concept of the internal environment to answer an objection to evolution by the American anti-Darwinian Alexander Aggasiz.21 The latter had claimed that the diversity of animals in the same environment argued against the possibility of natural selection. Lewes countered by stressing the similarities in their internal environment. Bernard himself varied between skepticism and dismissal of Darwinism, reflecting his view that if biological phenomena were not experimentally demonstrable they were of little validity.22 Yet, it was only when the profound evolutionary significance of the constitution of the internal environment was realized that Bernard’s idea finally had a major impact on physiology.
The development that catalyzed the understanding of Bernard’s milieu interieur was the comparison of the ionic concentrations of body fluids with those of seawater.23 In 1882, Leon Fredericq observed that the body fluids of ocean crabs, lobsters, and octopuses were about as salty as seawater, whereas marine fish, like freshwater ones, were much less salty. (He made these observations initially by taste.) He realized that this was the first evidence for Bernard’s idea that the internal milieu becomes increasingly independent of the external environment as one ascends the “living scale,” thereby providing the basis for the “free life” of higher organisms.24 Fredericq had studied in Paris with Paul Bert, a major student, collaborator, and biographer of Bernard (shown in figure 8.2). In marked contrast to Bernard, however, Fredericq interpreted his comparative observations as evidence for the evolution of the independence of the internal environment from the external one. By the end of the century, evolutionary thinking had finally made the constituents of the internal environment a meaningful subject. Independently, René Quinton and Archibald Macallum took the next step, arguing that life arose in the sea and that body fluids represented the original seawater that had been enclosed within the skin. More generally, it became clear that a major trend in evolution was the development of increasingly sophisticated mechanisms whereby the internal environment is protected from the external world.25
In the first decades of the twentieth century, Bernard’s ideas about the importance of the internal environment entered the mainstream of mammalian physiology both as a central explanatory concept and a program for research. Among the major British figures explicitly relating their work closely to Bernard’s idea were William Bayliss and E. H. Starling, codiscoverers of secretin, the first hormone identified; J. S. Haldane ( J. B. S. Haldane’s father) and Joseph Barcroft, pioneers in the regulatory functions of breathing; and C. S. Sherrington, a founder of modern neurophysiology. Starling seconded Macallum and Quinton’s ideas on the evolution of the internal environment and later coined the term “the wisdom of the body” for the maintenance of the internal constancies that Bernard had postulated.26 Barcroft claimed that the “principles . . . of the fixity of the internal environment have been as thoroughly established as any.”27 Haldane noted that Bernard’s conception “sums up and predicts” his own work on the regulation of blood composition by respiration.28 Sherrington suggested that “thenervous systemisthe highestexpressionof...themilieu interieur.”29
In the United States, the chief advocates of Bernard’s constancy ideas were L. J. Henderson and Walter B. Cannon, longtime members of the Harvard Medical School faculty. Henderson related his work on the maintenance of blood pH directly to Macallum’s marine biology as well as to Bernard.30 He helped bring Bernard to a wider American audience both in his introduction to the American translation of Bernard’s Introduction and in his own influential book, The Fitness of the Environment.31
Walter B. Cannon was particularly instrumental in making Bernard’s ideas central to the neurophysiology and psychology of the time. He coined the term homeostasis for the tendency of the mammalian organism to maintain a constant internal environment.32 His own major discoveries were in elucidating the role of the sympathetic nervous system in maintaining homeostasis; he brought these to the educated public in the classic The Wisdom of the Body (1932). Cannon viewed behavior as a homeostatic mechanism: shivering, seeking shelter, and putting on a coat were all examples of homeostatic mechanisms of temperature regulation. Writing at the height of the Great Depression, he suggested that some institutional arrangements for social homeostasis were sorely needed:
The main service of social homeostasis would be to support bodily homeostasis. It would therefore release the highest activities of the nervous system for adventure and achievement. With essential needs assured, the priceless unessentials could be freely sought.33
J. B. Watson and other early behaviorists such as Curt Richter rejected the myriad of previously postulated central drives as explanations for motivation. They turned instead to the experiments of Cannon for alternative and peripheral mechanisms of motivation and considered “motivated” behavior as a homeostatic mechanism. Thus, following him, they viewed thirst as a result of dryness in the mouth, which, when signaled to the brain, elicited drinking. Similarly, hunger was caused by stomach contractions (“pangs”), which signaled the brain to elicit eating. Extrapolating beyond Cannon, they interpreted sexual motivation to be due to tension in the gonads.34
Both Cannon and Henderson had extended Bernard’s ideas of self-regulation from the realm of bodily fluids to the wider social environment.35 The idea of self-regulation was extended even further to include the nonbiological world by Arturo Rosenblueth (one of Cannon’s collaborators), Norbert Weiner, and J. Bigelow.36 In the context of World War II control and communication systems, they pointed out that negative feedback covered self-regulation both in the nervous system and in nonliving machines. Soon after, Weiner coined the term cybernetics for “the entire field of control and communication theory, whether in the machine or in the animal.”37 Today, cybernetics, a formalization of Bernard’s constancy hypothesis, is viewed as one of critical antecedents of contemporary cognitive science.38
WHY WAS THE “ CONSTANCY OF THE INTERNAL eNVIRONMENT ” NOT UNDERSTOOD IN BERNARD’S TIME?
Despite the emphasis with which he repeatedly promulgated it, Claude Bernard’s insight that the “constancy of the internal environment is the condition for the free life” had no significance (indeed, no meaning) for biologists for more than 50 years. There seem to have been several reasons for this inability to process his idea. One was that Pasteur’s new bacteriology and its omnipresent, omnipotent germs were dominating the biomedical zeitgeist. Another, as discussed above, was the gap between evolutionary thought and general physiology. When this gap began to be closed through the comparison of the constituents of seawater and the bodily fluids at different phylogenetic stages, the constancy of the internal environment suddenly took on new and accessible meaning. Finally, the tools, techniques, and concepts for adequately measuring the internal environment were simply not available in Bernard’s time and for the rest of the century. For example, the work of Haldane, Henderson, and Barcroft required the development of organic and especially physical chemistry, as well as techniques for measuring ions, gases, and other components of the internal environment; the work of Sherrington and Cannon required the replacement of the reticular doctrine by the neuron doctrine, and the development of the cathode-ray tube oscilloscope and electrical stimulating devices.39
In the hi
story of biology there have been those, such as Gregor Men-del and Emmanuel Swedenborg, who were so far ahead of their time that they died unrecognized for their scientific work.40 Claude Bernard, by contrast, received every possible recognition as a scientist, yet what is today considered his most salient contribution had to wait half a century for advances in theory and practice to make it meaningful.
NOTES
This chapter was originally published as an article with the same title in The Neuroscientist (4: 380–385 [1998]). Parts of it were included in my later paper “Three before their time: Neuroscientists whose ideas were ignored by their contemporaries,” published in Experimental Brain Research (192: 321–334 [2009]).
1. Sigerist, 1933.
2. Olmsted, 1939; Olmsted and Olmsted, 1952; Grmek, 1970a.
3. Olmsted, 1944; Grmek, 1970b; Temkin, 1946a.
4. Elliott, 1987; Manuel, 1987; Rupke, 1987; Schiller, 1967; French, 1975.
5. Cranefield, 1974.
6. Olmsted, 1939; Olmsted and Olmsted, 1952; Grmek, 1970a; Grande, 1967; Robin, 1979.
7. Grmek, 1970a; Coleman, 1985; Wasserstein, 1996.
8. Bernard, 1961, 1974; Temkin, 1946b.
9. Grmek, 1970a; Holmes, 1974.
10. Olmsted, 1939; Olmsted and Olmsted, 1952.
11. Olmsted, 1939; Olmsted and Olmsted, 1952; Virtanen, 1960; Bernard, 1950, 1978.
12. Olmsted, 1939; Olmsted and Olmsted, 1952; Grmek, 1970a.
13. Olmsted, 1939; Olmsted and Olmsted, 1952; Virtanen, 1960.
14. Virtanen, 1960.
15. Virtanen, 1960.
16. Olmsted and Olmsted, 1952.
17. Olmsted and Olmsted, 1952.
18. Holmes, 1963, 67; Langley, 1973.
19. Bernard, 1974.
20. Olmsted, 1967; Foster, 1899; Flint, 1878; Holmes, 1965.
A Hole in the Head Page 15