For several decades it has been known that animals placed on a diet deficient in protein develop a hypoproteinemia. Weech and his associates1 of Columbia University, for example, showed that the decrease in serum protein is almost exclusively in the albumin fraction, the serum globulin remaining practically constant. It had been previously suggested by Holman and others2 that there is a "dynamic equilibrium between tissue protein and plasma protein," though no serious attempts were made to determine the mathematical laws governing the presumptive intracellular-extracellular protein interchange.
During the course of extensive nutritional experiments, Sachar and others3 at Washington University, St. Louis, obtained evidence in support of this assumed constant physicochemical balance. In a series of dogs maintained for three weeks on a protein free diet, for example, there was a fall in total serum albumin, calculated from the fall in albumin concentration multiplied by the total blood