_Two cubic centimeters of fresh gastric juice added to 8-10 c.c. Beveridge secretin, the mixture being kept at body temperature (38 C.), renders the secretin completely inactive in from 5 to 8 minutes_ (Fig. 2). There is no exception to this rule, as we have repeated the test on many different secretin preparations and using different samples of human gastric juice. The secretin of Beveridge is just as vulnerable as the secretin of Bayliss and Starling to pepsin-hydrochloric acid digestion. On what kind of tests does Beveridge base his claim that his secretin mixture acts on the pancreas when given by mouth? III. _The Relative Rate of Deterioration of the Secretin Solutions Prepared According to Bayliss and Starling and According to Beveridge._--Six different preparations of the two kinds of secretin were made, kept in dark stoppered bottles in the ice box, and tested by intravenous injection in dogs under ether anesthesia from time to time until all influence on the pancreas had been lost. One typical series of these tests is given by the way of illustration. (See Table on page 126.) [Illustration: Fig. 2.--Records of carotid blood pressure and flow of pancreatic juice on intravenous injection of secretin prepared by us according to the Beveridge method. _X_, injection of 10 c.c. of the secretin; _b_, record of flow of pancreatic juice in drops. Tracing _A_, the 10 c.c. of Beveridge’s secretin injected had been digested for five minutes with 3 c.c. of human gastric juice. Tracing _B_, injection of 10 c.c. of the same secretin preparation not subjected to gastric digestion. Showing rapid and complete destruction of Beveridge’s secretin by human gastric juice.] It will be seen that the rate of deterioration (oxidation or decomposition) of the secretin is practically the same whether prepared according to Bayliss and Starling or according to Beveridge (Figure 3). In both preparations the rate of deterioration is most rapid the first few days after preparation. It is scarcely necessary to point out that secretin preparations not kept constantly at low temperature and in the dark, as in the above experiments, will deteriorate more rapidly. [Illustration: Fig. 3.--Records of carotid blood pressure and flow of pancreatic juice on intravenous injection of secretin preparations. _X_, injection of 10 c.c. secretin; _b_, record of flow of pancreatic juice in drops. Tracing _A_, secretin prepared according to the Beveridge method September 30. _I_, injection of 10 c.c. October 2. _II_, injection of 10 c.c. November 30. Tracing _B_, secretin prepared by the Bayliss-Starling method September 30. _III_, injection of 10 c.c. October 2; _IV_, injection of 10 c.c. November 30. Showing no greater stability of Beveridge’s secretion over that of Bayliss and Starling.]