A perusal of the results obtained by the clinical and experimental use of atropine on gastric secretion is bewildering. In part, this is due to the facts that (1) different sorts of stimuli are used to induce secretion (various kinds of test meals, alcohol, histamine) and that these stimuli vary not only in quality but in quantity, (2) that the amounts of atropine used to inhibit the secretion vary and (3) that the atropine is administered in different ways, for instance, by mouth or subcutaneously. Nevertheless, the impression is gained that the foregoing variables alone do not account for the diversity of results. The commonly accepted classification of gastric secretion is: (1) the primary or cephalic, (2) the secondary or gastric and (3) the intestinal. The primary phase is reflex, and the impulse is transmitted to the stomach over the vagi following the seeing, smelling, tasting or chewing of food.