It is possibile to reproduce all the ecg alterations typical of myocardial infarction (deviation of the S-T interval, inversion of the T wave, transformation of the initial part of the ventricular complex in the corresponding deflection into the QS wave) by placing a strip of necrotic tissue on the surface of the intact myocardium. In such an experimental "myocardial infarction" the property of excitation and contraction of the part of the myocardium in contact with the necrotic tissue and neighboring structures is lost. This produces a zone of functional paralytic myocardium around the area of application of the necrotic tissue and near that area near-nerotic zone. It a strip of necrotic tissue is applied near the atrioventricular bundle, reversible injuries of atrioventricular conduction develop which are typical of infarction of certain locations (syndrome of WPW on through Wenken-bach''s periods and finishing in complete block). After the necrotic tissue is removed a normal ecg and electrogram are seen. The ecg returns to normal in the same manner as after "real" infarction. The mechanism of the effect of necrotic tissue upon healthy myocardial tissue is due to the K ions coming out of the injured cells. Necrotic tissue blocks the conduction of excitation in nervous fibers, paralyzes brain tissue and injures reflex action of corresponding sections of the central nervous system.