Bernard, behr NAHR, Claude (1813-1878), the leading French physiologist of his day, founded modern experimental physiology. He studied many aspects of digestion and nerve function. Bernard discovered that the liver converts sugar to glycogen (animal starch), a substance used to maintain blood sugar levels. He also found that juices of the pancreas help digest and absorb fats. In addition, Bernard discovered how the nervous system controls blood circulation. His other important work included research on how drugs and poisons affect the body.