Bernard, Claude (1813-1878), the leading French physiologist of his day, was the founder of modern experimental physiology. Physiology is the study of how living things function.

Born in the Beaujolais region of France, Bernard was the son of a wine grower who became a schoolteacher after his venture into wine-marketing failed. The family was left in debt alter his death in 1847.

After studying Latin with the local priest, Bernard went to a Jesuit school at Villefranche, where the curriculum included no science. At 19, still lacking a diploma, Bernard was apprenticed to a pharmacist. In the fall of 1834, he completed a manuscript of a five-act heroic drama. Literary critic Saint-Marc Girardin read the play and advised Bernard to abandon playwriting and go to medical school instead.

After barely qualifying in 1839, Bernard worked in several Paris hospitals. He came to the attention of the well-known doctor Francois Magendie, who admired Bernard's fine dissections. Magendie hired him to assist in his research on spinal nerves. This post exposed Bernard to work in neurology and metabolism, and he published papers in both fields. In 1843, Bernard was awarded his doctorate in medicine. His thesis was on the function of gastric juice in digestion.

Although he failed the exam that would have qualified him to teach medical school, Bernard continued collaborative research on digestion and on the poison, curare. In 1844, by now 31, he resigned his research assistantship and began to consider medical practice again.

In 1846, he made the important discovery that during digestion, pancreatic secretions break down fat molecules into fatty acid and glycerin. He also demonstrated that sugar in the blood is not always symptomatic of diabetes. Next Bernard discovered that the liver converts sugar to glycogen (animal starch), a substance used to maintain blood sugar levels. He earned a doctorate of science in 1853 with a dissertation on this topic. In addition, Bernard discovered how the nervous system controls blood circulation. His final major discovery was that curare causes paralysis and death by attacking the motor nerves without affecting the sensory nerves.

In 1854, Bernard was elected to the Academy of Sciences and appointed chair of general physiology, a position created especially for him by the government. At Magendie's death in 1855, Bernard became professor of medicine at the College de France. He became a member of the Academie de Medecine in 1861. Bernard played a major role in establishing how experiments in the life sciences should be carried out. Experiments should be designed to either confirm or refute the guiding hypothesis with which researchers embark on their investigations.

In 1865, Bernard's most famous book, Introduction to the Study of Experimental Medicine, was published. In it he argued that medicine would only progress if based on experimental physiology. He also refuted the idea of the “vital force” as a satisfactory explanation for life. He proposed the idea of an “internal environment”– consisting of the humors (blood, phlegm, cholera [yellow bile], and melancholy [black bile]), the blood, and the lymph-that remains stable despite changes within and without the organism. When this stable environment is disturbed, the organism immediately sets about to restore it. The book led to his election to the French Academy.

In the 1870's, Bernard began research in a new field that led to the publication, after his death, of Phenomena of Life Common to Animals and Plants. Bernard died Feb. 10, 1878, in Paris, of kidney disease. He was the first French scientist whose achievements were celebrated with a state funeral.