_Results._--In only one case was a slight response obtained, the others gave none. Small and large doses were equally inert (Table 7, Figs. 2, 3). The preparations, though inert, always produced a depression in blood pressure, sometimes even greater than that caused by active secretin. Among our many tests, one bottle was found, however, to be a little different from the rest (Experiment 4). Its entire content, 100 tablets, had been ground and boiled in 0.9 per cent. sodium chlorid. The extract on injection was found to have a small but unmistakable secretin reaction, equivalent to about 2 c.c. of the control secretin used. But repeated experiments were unable to duplicate this result. The “Secretogen” and “Elixir Secretogen” were all supposedly fresh preparations, the retail drug store informing us that a fresh supply was obtained from the wholesale house each week. Secretogen, then, contains practically no secretin, and even if it did contain secretin, it can have no effect on the pancreas when taken by mouth. The indications for Secretogen, therefore, are based on false premises, and the testimonials are worthless. [Illustration: Fig. 2.--Tracings (reduced one-half) showing no stimulation of the pancreas by Secretogen, Elixir Secretogen, and Duodenin, even when administered intravenously in quantities one hundred times greater than the therapeutic dose by mouth. Dog: Light ether anesthesia; cannula in the pancreatic duct; _a_, carotid blood pressure; _b_, flow of pancreatic juice in drops. Tracing A: at _x_, intravenous injection of 10 c.c. secretin prepared from duodenal mucosa of dog. Tracing B: at _x_, intravenous injection of 100 tablets of Secretogen digested with 0.4 hydrochloric acid and neutralized. Tracing C: at _x_, intravenous injection of 100 tablets of Secretogen, prepared as in Tracing B. Tracing D: at _x_, intravenous injection of 50 c.c. Elixir Secretogen. Tracing E: at _x_, intravenous injection of 100 tablets of Duodenin (dissolved in 0.9 per cent. sodium chlorid).] _Duodenin._--This is a preparation manufactured by Armour & Company, which purports to be “secretin plus enterokinase.” The claims for this product are similar to those for Secretogen, but somewhat less sweeping. According to the manufacturers, “Duodenin (Armour) is recommended in the treatment of intestinal disorders where an increased flow of pancreatic, hepatic and intestinal secretion is desired. It is of specific value in proteid digestion on the theory that secretin and enterokinase stimulate the pancreas and activate its secretion.”