The less efficient utilization of cow's milk as compared with breast milk in infant feeding is usually assumed to be due to differences in ease of digestion. The slower and less complete digestion of cow's milk has been ascribed to its high buffer effect in neutralizing the acidity of gastric juice and to the hard, tough curds formed in the stomach. Most of the adaptations of cow's milk to infant feeding have had as their object the correction either of the curd or of the ph. The earlier modifications, such as alkalizing, boiling and predigesting milk or adding starchy diluents, had as their primary purpose the prevention of a hard, leathery curd. More recently, emphasis has been placed on the relation of thephto peptic digestion, and a number of acidified milks have been introduced. The proponents of these acid milks—hydrochloric acid, lactic acid (both cultured and artificially