In a recent study of experimental crush injuries great elevation of creatine in the blood and the urine was observed.1 This elevation was believed to arise chiefly from injury to skeletal muscle. Since at least a large part of the creatine in muscle exists in combination with phosphoric acid, it seemed likely that inorganic phosphate would also be liberated. Accordingly, the levels of serum inorganic phosphorus were determined for several animals subjected to these injuries and were found to be strikingly high. A more detailed study, including shock produced by other methods, was then undertaken. EXPERIMENTAL METHOD Dogs were used in all experiments. Anesthesia was produced by the subcutaneous injection of 0.030 Gm. of morphine sulfate followed thirty minutes later by the intravenous injection of soluble pentobarbital U. S. P. (pentobarbital sodium) in doses of 0.02 Gm. per kilogram of body weight. Subsequent injections of 0.006 Gm. per kilogram