Bayliss, William Maddock (1860–1924)

English physiologist who discovered the digestive hormone secretin, the first hormone to be found, with Ernest Starling in 1902. During World War I, Bayliss introduced the use of saline (salt water) injections to help the injured recover from shock. Knighted in 1922.

Bayliss was born in Wolverhampton, Staffordshire, and studied at University College, London, and at Oxford, becoming professor at University College.

By experimenting with the inner lining of the duodenum (first part of the intestines), Bayliss concluded that as hydrochloric acid from the stomach's digestive juices passes into the duodenum during the normal digestive process, the duodenal lining releases a chemical into the bloodstream which, in turn, makes the pancreas secrete its juices. This is the hormone secretin.

Bayliss went on to study the activation of enzymes, particularly the pancreatic enzyme trypsin. Bayliss and Starling also investigated the peristaltic movements of the intestines and their nerve supply, and pressures within the venous and arterial systems.

Bayliss's Principles of General Physiology (1915) became a standard work.