Abstract
Deflections of ST-T in E.C.G., produced by constant current flowing through the heart, were studied in toads.
1. In the E.C.G. led usually in situ, the deflection varied individually and according to experimental conditions, but some regularity could be found under suitable conditions on the same individual. The deflection of ST-T was reversed with reversed direction of the current and disappeared with cessation of the current. The degree of the deflection was proportional to the current strength.
2. In E.C.G. taken directly from the excised heart, the nearer the recording electrode was placed to the applying, the greater the deflection of ST-T was, and its direction indicated that the potential became higher at the anodal and lower at the cathodal region. Just after the cessation of the current the deflection was reversed.
3. The electrogram led from the sinoauricular preparation with intracavity leading showed a similar deflection during atrial systole and even during passive deflation.
