born May 2, 1860, Wolverhampton, Staffordshire, Eng.
died Aug. 27, 1924, London
British physiologist.
He and Ernest H. Starling studied nerve-controlled blood-vessel contraction and dilation and discovered the peristaltic wave. In 1902 they showed that dilute hydrochloric acid mixed with partly digested food activates a chemical in the duodenum that they called secretin, because it stimulates secretion of pancreatic juice. This marked the discovery of hormones, a term the men coined. Bayliss also showed how the enzyme trypsin was formed from inactive trypsinogen and measured precisely the time it took to digest protein. His recommendation of gum-saline injections for wound shock saved many lives in World War I.