The creation of an isolated gastric pouch in experimental animals has contributed more than any other procedure to the present understanding of the physiology of gastric secretion. The extraordinary usefulness of the pouch depends on the fact that it permits quantitative collection of secretion uncontaminated by material from either the esophagus or the duodenum. In no human being, even one with a chance abnormality of the stomach, has a quantitative collection of uncontaminated gastric secretion been obtainable. In patients with pyloric obstruction, for example, gastric secretion is contaminated by saliva; in patients with esophageal obstruction and gastric fistulas the secretion is contaminated by unknown quantities of duodenal contents. In such patients the disease has usually produced nutritional disturbances not conducive to normal secretory function. The gastric pouch itself, however, has presented drawbacks. Digestion of the abdominal wall by the gastric secretion has prevented maintenance of a sphincter at the outlet