The present work was undertaken to learn the effect of gastric juice on the rate of healing of acute gastric and duodenal ulcers. It is well known that lesions of the gastric and duodenal mucosa heal readily in the presence of active gastric juice. Small abrasions of the stomach mucosa, such as those following at times the administration of a stomach tube, are common, occasion no discomfort to the individual, and in a majority of cases heal without further sequelae. Surgical operations in which there is a maximum insult to the mucosa cells are not commonly followed by untoward effects due to the digestive activity of the gastric juice. Nevertheless, up to the present, the medical and surgical treatment of gastric and duodenal ulcers has been based essentially on the theory that the gastric juice induces chronicity of these ulcers by digesting the exposed edges of the mucosa. This is