1905

Ernest Starling, Edward Schäfer’s successor at University College, introduces the term “hormone” (Borell), which he defined “as a chemical substance produced in one of the organs of the body and transported via the blood to cause some form of reaction in another part of the body” (Nordlund, 88). In 1902, Starling and William Bayliss, another of Schäfer’s younger colleagues, discovered that a crude extract of duodenal mucosa injected into the bloodstream of an experimental animal effected pancreatic secretion; they named that active substance “secretin’: “After 1902, therefore, internal secretions acquired a new significance as chemical effectors in the body. In 1905 Starling, as noted, introduced the word hormone to signify this role. At the same time, he pointed out that although chemical substances were as important to physiological regulation as nervous stimuli, their study had previously been overlooked. Many unexplained phenomena might now be approached by considering the action of specific chemical messengers called ‘hormones.’ Physiological investigators thus began actively to search for these substances, using a greater variety of physiological tests than previously” (Borell IV, 11).