William Maddock Bayliss (1860-1924), British physiologist and co-founder of endocrinology. Bayliss worked at University College London with Ernest Henry Starling. They studied the nervous system, the vascular system and the movement of food down the intestine. They discovered that pancreatic secretions are controlled by a substance they named secretin, one of a new type of chemical called hormones. Bayliss was elected Fellow of the Royal Society (1903), awarded the Royal Medal (1911) and Copley Medal (1919), and was knighted (1922). Photographed at Bayliss's laboratory desk in the Physiological Institute of University College, London, UK.