Owing to the clinical and experimental investigations of Krehl, Engelmann, Hering, Erlanger, MacKenzie, Aschoff, Tawara and others, the more exact diagnosis of cardiac disease has become both possible and imperative. Among the questions of vital importance in certain forms of cardiac disease is the synchronicity or time relations between the movements of the auricle and ventricle. Under normal conditions the cardiac cycle begins with the auricular contraction, the impulse from which is transmitted through the bundle of His to the ventricle which should contract in a certain average time after the auricle. While there are those still who believe that the ventricle contracts from other causes, such, for instance, as distension with blood, the evidence seems to me to be entirely conclusive that its normal excitation is received through the conducting fibers above referred to, although an inherent rhythmicity of the ventricular wall is certainly a reserve mechanism, while it