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Claude Bernard (French physiologist)

French physiologist (1813-1878)

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Bernard, CLAUDE.—French physiologist, b. July 12, 1813 at Saint Julien near Villefranche, France; d. at Paris, February 10, 1878. His father was the proprietor of a vineyard and his early education, which was begun by the village cure, was obtained at the Jesuit college in Villefranche. Going to Lyons to continue his studies, he became instead a pharmacist’s assistant. While here, his literary ambitions led him to write a comedy, “La rose du Rhone”, which was put on the stage. Encouraged by its reception, he wrote a five act drama and setting out In 1834 for Paris, submitted it to Saint Marc Girardin, the well-known critic. The latter found evidence of literary ability in the young author’s work, but advised him to study medicine as a more certain means of securing a livelihood than literature. Bernard followed this counsel, which proved the turning point in his career, and the play “Arthur de Bretagne” was not published until long after his death in 1886.

Bernard devoted himself particularly to anatomy and physiology but, being of a retiring disposition and somewhat awkward in manner, he did not impress his professors or fellow students with the power of which he was later to give proof. In 1839, he was appointed interne to Magendie, professor of medicine at the College de France, and one of the physicians of the Hotel Dieu, noticing his skill in dissection, soon made him his preparateur, or lecture assistant. This latter appointment, in spite of many disadvantages, proved a fortunate one, and Bernard now began the researches in physiology which made him famous. His first important work was a study of the pancreas and its functions. This was followed by the discovery of the glycogenic function of the liver—perhaps his most noteworthy achievement, particularly on account of its bearing on current views in biology. It had been supposed by biologists that the animal, unlike the plant, could not build up complex compounds within itself, but could only utilize those furnished by the plant such as carbohydrates, proteids, etc., resolving them into constituents suited to its own needs. Bernard undertook the task of tracing out the various transformations of food stuffs within the animal organism, beginning with the carbohydrates; and he not only found, contrary to the accepted view, that sugar was formed in the liver, but he was also able to isolate a substance from the hepatic tissue which, though not sugar, was converted by fermentation into dextrose. He made a special study of its properties and called it “glycogen”.

Bernard did not pursue his investigations in this field any farther, but took up the study of the influence of the nervous system on animal heat. This led to the discovery of the vaso-motor system. He found that severing the cervical sympathetic on one Side of the neck of a rabbit caused a sensible rise in the temperature of the affected region. Further experiments on the sub-maxillary and other glands showed, as he announced to the Academie des Sciences, in 1858, that when the gland is actively secreting, the venous blood issuing from it is red. Two sets of nerves control the action of the gland, stimulation of the chorda tympani making the venous blood red, while stimulation of the sympathetic nerve makes it darker than usual. He was thus able to formulate the statement: “the sympathetic nerve is the constrictor of the blood vessels; the chorda tympani is their dilator”, and it may be said with truth that all subsequent work on the vasomotor system has been based on these researches. The physiological effects of poisons, particularly of curare and carbon monoxide, also engaged Bernard’s attention. He found that the former—an arrow poison employed by South American Indians—rendered the motor nerves inactive, while the sensory and central nervous system remained intact. His analysis of the action of the latter showed that it instantly replaces the oxygen of the red blood corpuscles, while it cannot of itself be subsequently replaced by oxygen.

In 1855 Bernard succeeded Magendie as professor at the College de France, having been appointed his deputy as early as 1847. In 1862 his health failed and it was not until 1870 that he fully recovered. In his later years he made the acquaintance of Napoleon III, who was much impressed by him and established two well-equipped laboratories for him—one at the Sorbonne, the other at the Musee d’Histoire Naturelle. In 1867 the emperor made him a member of the Senate, and in 1868 he was admitted to the Academie des Sciences. He devoted himself to scientific work and the revision of his published lectures until shortly before his death. He received a public funeral, at the expense of the State, from the Cathedral of Notre Dame, being the first Frenchman of science to be thus honored. A statue was erected in his honor in 1886 in the court of the College de France, and also, in 1894, in the court of the Faculty of Medicine at Lyons. Bernard’s chief contribution to physiological literature, apart from his original papers presented to various societies, are his “Lecons”, in seventeen volumes, upon various topics in physiology. These comprise his lecture courses which were reported by his students and revised by himself.


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