Following our study of hyaline cast production after the intramuscular or intravenous injection of hydrated magnesium sulphate and certain other salts, reported to this society in February and June of this year,1 Dr. Meltzer suggested that the investigation be carried further by a series of experiments in which the MgSO4 was given directly into the intestines, simulating its use as a purgative.The typical procedure in the present series was to inject an m/1 solution of hydrated MgSO4, in doses of .18 or .2 gm. per kilo. body weight, through a glass cannula into the upper duodenum. The small intestine was isolated by ligatures just below the pylorus and at the ileo-cecal valve. The operation was performed under complete ether anesthesia and the dogs were killed at the end of five or six hours. For two animals the solution was diluted to m/3 before injection and in three other cases the ligature was not placed at the ileo-cecal valve. In each case control urines were examined for casts and albumin.Of twelve...