The glycogen content of the right and left gastrocnemius muscle, when extirpated at 30 min. intervals from rats under amytal anesthesia (6, and 6 controls), was found to be of the same magnitude. When after extirpation of the 1st muscle epinephrine was injected either subcutaneously or by means of an intravenous infusion at a constant rate, a definite reduction in the glycogen content of the 2nd muscle was always encountered (6 experimental rats and 6 controls) . Twenty and 40 min. after epinephrine injection the phosphocreatine content of muscle was practically unchanged, the inorganic phosphate showed a slight decrease and the lactic acid content of muscle and of blood was markedly elevated.