Although the function of creatine in muscle has not been entirely elucidated, recent studies indicate that in the form of phosphocreatine it plays a vital rôle in muscular contraction. Data on the creatine content of the heart, the body's most active muscle, should possess considerable significance. When one of us (D. P. S.) was approached with regard to collaborating on a study of the creatine content of the heart, an idea formulated during the progress of pathologic studies, namely, that the left and right ventricles were qualitatively different muscles, led to the decision to make separate determinations on the two ventricles.
The idea that the ventricles may be different originated about ten years ago, during a review of the available data on the congenital anomalies of the heart which result from defects of development of the bulbus cordis. As summarized by Keith,1 the data disclosed that the conus of