The role of avian biliary excretion and that of a new pancreatic polypeptide in the reported "resistance" of Aves to insulin injection was studied. Bile was collected in 15-minute collection periods from adult chickens after the injection of beef insulin, 14C-inulin, or beef insulin and 14C-inulin. The volume of bile was noted as well as its 14C-activity (when appropriate). It was found that beef insulin injections increase the bile flow and appearance of 14C-activity in the bile. [...]