Ernest Starling and the discovery of secretin

The demonstration by Bayliss and Starling that acid liberates a chemical messenger from the cells of the duodenal and jejunal mucosa and that this, by traveling through the blood, excites the pancreas to secrete revolutionized physiology. It subsequently provided the impetus to establish endocrinology as a specialist field in medicine. Together, their contributions to physiology covered a vast sphere of knowledge, ranging from hormones to the heart and from enzymes to osmotic forces. Every subject that they studied was augmented by their efforts, and their lucid scientific writing brought both clarity and organization to the field of physiological endeavor throughout the world. Both contributed in a very definite way to crystallizing physiology into a rigorous scientific discipline and their respective texts the "Principles of General Physiology" (Bayliss) and the "Principles of Human Physiology" (Starling) established a framework of thought that for decades remained the lodestar of physiological science. As mentors, they devoted themselves to aspirant physiologists from all parts of the world, and their dedication to the activities of the Physiological Society in London was legendary. Indeed from 1896, when Starling became secretary, until the death of Bayliss in 1924, the two ran this august body in one capacity or another for more than a quarter of a century. There is little doubt that the felicitous collaboration that led to the discovery of secretin and the introduction of the concept of chemical messengers represents an advance that not only revolutionized physiological thought but the entire face of clinical medicine.