It has long been known that during the febrile reaction to acute infections the katabolism of protein is intensified, resulting in an increased excretion of nitrogenous substances in the urine. This phenomenon is of such constant occurrence that it may properly be considered a characteristic of fever. Because of this increased katabolism and of the disproportion between the anabolism and katabolism of protein the subject becomes poorer in nitrogenous substances. After the termination of the disease the protein katabolism falls in intensity to or even below the normal limit, the anabolic process becomes more prominent, and during this reverse disproportion between the processes of assimilation and destruction the organism repairs its losses of protein and other substances. These conditions, fever and convalescence, afford two of the most interesting fields for the investigation of the complicated principles of physiological and pathological nutrition, as has been demonstrated by the