The essential relationship between the gastric lesion produced by pituitary extract and the oxyntic cell-bearing area of the stomach mucosa has been pointed out in the previous paper. This and the fact that animals with gastric contents of high acidity are the most susceptible, together with the demonstration that neutralization of this acidity will prevent the pro duction of a lesion (Dodds, Hills, Noble and Williams 1935), suggested that acid secretion by the stomach played an important part

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... n the production of the lesion. It was necessary, therefore, to continue these observations on gastric secretion. In the following experiments on gastric secretion a standard routine had been adopted and has been employed except where otherwise stated. In acute experiments rabbits have been anaesthetized with sodium amytaland cats with " Nembutal". Aglass gastric cannula has been stitched into the most dependent part of the stomach, and the pylorus tied off. Animals with a previously established permanent fistula have not had the pylorus ligated. The cats have been kept without food for 24 hours previous to any tests, but in the case of the rabbits the stomach was emptied by a technique previously described (Dodds and others 1935) . A 30 min. specimen of fasting gastric juice had been collected, and in most cases this included the fasting contents of the stomach. Ergamine acid phosphate (histamine) has been administered by subcutaneous injection, and half-* N atio n al R esearch Council Fellow , th e U n ited S tates of A m erica, f L everhulm e Fellow , R o y al College of P hysicians, t R eceiving a g ra n t from th e M edical R esearch Council.