In a recent contribution to the physiology of digestion from the Physiological Laboratory of the University of Vienna, Albert Muller1 has made the announcement that the digestion of meat regularly proceeds in the stomach of healthy, normal dogs in the absence of free hydrochloric acid. He insists, further, that free HCl is lacking with all foodstuffs throughout the progress of gastric digestion in these animals. The total acidity is reported to reach high values in meat digestion and lower figures with other dietaries; but in each instance it is referable to combined acid. The ability of the dog's stomach to secrete a juice rich in free HCl is not questioned. In the case of this animal, however, Muller believes that the production of acid is limited by the demands of the digesting materials. As soon as the proteins present, or their cleavage products, are combined with acid, the further secretion of the latter ceases. The same behavior is said to characterize the gastric digestion of the cat; not, however...