SUMMARY1. Pancreotone is a polypeptide material obtained from ileal and colonic mucosa by extraction with alcohol and subsequent precipitation by bile salts.2. In anaesthetized cats it inhibits the actions of secretin on the pancreas, and of pancreozymin on the pancreas and gall-bladder.3. Pancreotone has a less powerful inhibitory action on pentagastrin-stimulated gastric secretion.4. The actions of pancreotone resemble the inhibitory effects on the pancreas and stomach of intraileal and intracolonic infusions of oleic acid and other substances in cats with the vagal and splanchnic nerves cut. Pancreotone may be the humoral mediator of these inhibitory effects.5. A possible relationship between the actions of pancreotone and somatostatin on the stomach, and of pancreotone and pancreatic polypeptide on the pancreas, is discussed.

SUMMARY1. Infusions of oleic acid into the colon or the distal part of the ileum in anaesthetized cats inhibits secretion of water and amylase by the pancreas, stimulated by secretin and pancreozymin. Intraileal infusions of other non-water-soluble substances or hypertonic solutions can also inhibit the pancreas.2. As inhibition can be produced after extrinsic denervation of the pancreas and gut, it must in part be humorally mediated.3. Pentagastrin-stimulated gastric secretion of acid and pepsin is also inhibited by the intraileal infusions, but the inhibition of acid secretion is less than that of pancreatic secretion.4. It is suggested that the physiological counterpart of the inhibitory effects induced by the infusion of non-physiological solutions into the colon or ileum is an inhibition of pancreatic secretion brought about by the cessation of intestinal absorption, which marks the completion of the post-prandial digestive process.