(b. Maureilhan, near Béziers, France, 13 April 1794; d. Montgeron, near Paris, France, 8 December 1867)
physiology, history of science.
Pierre Flourens, as he signed his papers, was born into a humble family in a small town in southern France. He studied medicine at the University of Montpellier, graduating at the age of nineteen. The next year, with a letter of recommendation from the famous botanist Augustin de Candolle to Georges Cuvier, Flourens went to Paris, where he decided to abandon medicine and devote all his efforts and ingenuity to physiological research. The protégé of Cuvier, talented, unusually skillful in experimental work, industrious, persevering, and devoted to research and science, Flourens met with early success. In 1821 he was entrusted with lecturing on the physiological theory of sensations before the distinguished scientific Cercle Athénée, and this led him to deeper experimental study of nervous functions. The first results, presented to the Academy by Cuvier in 1822, earned Flourens notoriety and recognition among scientists.
In 1824 and 1825 Flourens received the Montyon Prize twice in succession, and in 1828 he became a member of the Academy of Sciences. That same year Cuvier made Flourens his deputy lecturer at the Collège de France, and he became professor in 1832. The next year, following a wish of Cuvier’s expressed before his death, Flourens succeeded him as permanent secretary of the Academy of Sciences. One of his great achievements in this capacity was the founding, with Arago, of the Comptes rendus, reports of Academy meetings, which still constitute one of the most important scientific periodicals. In 1838 Flourens was elected deputy for Béziers, and two years later he won election to the French Academy against the celebrated poet Victor Hugo; the election was followed by bitter comments and criticism. In his remaining years Flourens devoted his activity mainly to scientific biographies and philosophical and popular writings. He died at his country house after a long illness.
Flourens’ distinguished scientific career began in 1822 with Cuvier’s presentation to the Academy of Sciences of the first in a series of his reports on the nervous system; they were collected into a volume in 1824, which was followed by a complementary volume in 1825, and were republished with supplementary material in 1842. These reports are a landmark in the history of the physiology of the nervous system. Flourens’ idea was to break down the complicated facts—everything in the mechanisms of life is complex, phenomena as well as organs—into their simple components, to separate all diverse occurrences, to find all distinguishable parts. The art of separating simple facts was for Flourens the whole art of experimenting. In his studies of brain functions he used mainly the technique of ablation—surgical removal of different parts to study their functions—examining systematically one part after the other to differentiate their functions. His hand was sure and precise; his descriptions clear, trenchant, simple, and elegant.
Flourens distinguished three essentially distinct main faculties in the central nervous system: perception and volition (i.e., intelligence), reception and transmission of impressions (i.e., sensibility), and the excitation of muscular contractions. He distinguished excitability from contractility, which is the faculty of muscle to shorten when excited by an adequate stimulus. According to Flourens, the intellect and the faculty of perception reside in the brain proper (cerebral hemispheres), the faculty of immediate excitation of muscular contraction in the spinal cord; and the faculty of coordination of movements willed by the cerebral hemispheres resides in the cerebellum, lesions of which cause disturbances of coordination (i.e., disharmony of movement) and of equilibrium. The idea of coordination introduced by Flourens has played an important role in nervous physiology. For Flourens every part of the brain—“every organ”—had its specific function yet acted as a whole in respect to this function, just as the entire brain functioned as a whole. Thus he thought that there was no localization within each part: all perceptions could concurrently occupy the same seats in the forebrain. Flourens was strongly opposed to Gall’s phrenology.
Another important advance was Flourens’ discovery of compulsive movements of the head and disturbances of equilibrium after lesions of the semicircular canals of the inner ear (1824–1828). This was a puzzling phenomenon whose physiological background he could not elucidate. It was at that time extremely difficult to realize that the inner ear has not only the receptors of audition (in the cochlea), but also, in its vestibular part, another type of receptor reacting to gravity and accelerative forces. It was explained only fifty years later, in 1873–1874, by Ernst Mach, Josef Breuer, and Alexander Crum Brown simultaneously. Among Flourens’ other important contributions to science were his classic localization of the respiratory center (noeud vital) in the medulla oblongata, the reunion of nerves (1827), the role of the periosteum in the formation and growth of bone (1842–1847), and the discovery of the anesthetic properties of chloroform on animals (1847).
Flourens had a great influence on the development of physiology, but sometimes it was not beneficial. He was often authoritarian, imposing his opinion without caution or comparison of his experimental results and interpretations with those of other scientists. He was usually right, as in his opposition to Gall’s pseudoscience of phrenology, but sometimes wrong, as in his repudiation of every idea of localization in the brain. His most reproachable error was his criticism of Darwin’s work (1864).
In his biographies of distinguished scientists Flourens tried to sum up their achievements, relating their work to what was done before and after along the same lines, in a clear, simple, elegant, and engaging style. Some biographies are accompanied by more general studies on the related problems of the history of science. They were very popular, and some are masterpieces which served as models for other biographies.
I. Original Works. Flourens’ writings are Recherches expérimentales sur les propriétés et fonctions du système nerveux dans les animaux vertébrés (Paris, 1824, 1842); Expériences sur le système nerveux . . . faisant suite aux Recherches expérimentales . . . (Paris, 1825); Cours sur la génération, l’ovologie et l’embryologie (Paris, 1836); Examen de la phrénologie (Paris, 1842); Recherches sur le développement des os et des dents (Paris, 1842); Mémoires d’anatomie et de physiologie comparées (Paris, 1843); Histoire des travaux et des idées de Buffon (Paris, 1844); Histoire de la découverte de la circulation du sang (Paris, 1854, 1857), also trans. into English (Cincinnati, 1859); De la longévité humaine et de la quantité de vie sur le globe (Paris, 1854), also trans. into English (London, 1855); Cours de physiologie comparée (Paris, 1856); Recueil des éloges historiques, 3 vols. (Paris, 1856–1862); Éloge historique de François Magendie (Paris, 1858); De l’instinct et de l’intelligence des animaux. De la vie et de l’intelligence (Paris, 1858); Ontologie naturelle ou étude philosophique des êtres (Paris, 1861); Éloge historique de A. M. C. Duméril (Paris, 1863); and Examen du livre de M. Darwin sur l’origine des espèces (Paris, 1864).
II. Secondary Literature. On Flourens or his work, see Claude Bernard, “Discours de réception,” in Recueil des discours, rapports et pièces diverses . . . de l’Académie française 1860–1869 (Paris, 1872), II, 319; E. G. Boring, A History of Experimental Psychology, 2nd ed. (New York, 1950), pp. 61–67, 69, 77–78; H. Buess, “Flourens, 1794–1867, l’un des créateurs de la neurophysiologie,” in Médecine et hygiène, 25 (1967), 1377–1379; E. Clarke and C. D. O’Malley, Human Brain and Spinal Cord. A Historical Study Illustrated by Writings from Antiquity to the Twentieth Century (Berkeley-Los Angeles, 1968), pp. 483–488, 656–661; V. Kruta, “M. J. P. Flourens, J. E. Purkyne et les débuts de la physiologie de la posture et de l’équilibre,” in Conférences du Palais de la découverte, no. D98 (1964); M. Neuburger, Die historische Entwicklung der experimentellen Gehirn und Rückenmark’s Physiologie vor Flourens (Stuttgart, 1897); J. M. D. Olmsted, “Pierre Flourens,” in Science, Medicine and History. Essays in Honour of Charles Singer (London-New York-Toronto, 1953), II, 290–302; M. Reynaud, Des derniers ouvrages de M. Flourens et de l’origine des idées modernes sur la vie (Paris, 1858); and A. Vulpian, Éloge historique de M. Flourens . . . (Paris, 1886).