The ventricles occasionally escape from the control of the sinuauricular node through the independent action of their own center of stimulus production in the atrioventricular junctional tissues. Two types of such ventricular escape should be recognized : first, that which is dependent primarily on a depression of the pacemaker in the sinuauricular node; and second, that which is dependent primarily on an excitation of the pacemaker in the atrioventricular node. As one would anticipate, examples of the first type are occasionally seen, while instances of the second type appear to be decidedly rare, though both conditions may be more common than we realize at present. The two factors, depression of the sinu-auricular node and the excitation of the atrioventricular node, may be found in a single case. The differentiation between the two types must be based largely on the rate of the sinu-auricular pacemaker from which the ventricles