In 1944 Magalhães and Dias (Memórias do Instituto Oswaldo Cruz) studied the action of emetic tartar in the dog and in man in toxic and therapeutic doses, respectively, on the electrocardiogram. They concluded that there were signs of miocardic suppering, that must be connected with a deficiency of oxigenation, determined by the diminution of the circulating blood. The latter, in its turn, must be connected with stagnation, function of the dilatation-vessel. The present work is a complement to the former one. In the experiments, isolated hearts of dogs were used in Herlitzke apparatus; solutions of emetic tartar in varied concentrations, being passed over them - the emetic tartar produced the following actions: - I - It diminishes the contractibility; II - It diminishes the conductibility; III - It increases the excitability; IV - These phenomena are reversed, if the solution of emetic tartar in Locke, is substituted by pure Locke.