The New Student's Reference Work/Pepsin

Pep'sin, a substance contained in the gastric juice and the mucous membrane of the stomach, to which the gastric juice largely owes its power of dissolving the contents of the stomach and converting them into chyme. Various plans have been devised for extracting pepsin from the stomachs of calves, pigs and other animals; but it has never yet been obtained in its purity, and its chemical constitution is unknown. Pepsin has been used to a considerable extent in medical practice in cases of weak or disordered digestion; and it is an ingredient in most of the digestive preparations now in the market.