Injn. of 0.05 ml. of a soln. of 0.05% of aconitine crystals (Merck) into the wall of the appendix of the left or right auricles leads to the appearance of an auricular tachycardia with a rate between 196 and 310/min. Faradic stimulation of the vagi in the neck regularly caused an increase of auricular rate. Clamping off the appendix or the focus of injn. from the rest of the auricle led to an immediate disappearance of the tachycardia; the same effect was accomplished by cooling the focus of origin of the tachycardia. It is difficult to decide whether the mechanism is auricular flutter or a heterotopic paroxysmal tachycardia. It is difficult to explain by the circus movement theory why the tachycardia abolished by the cooling always reappeared immediately when the cooling was interrupted. If the mechanism is not a circus movement, the appearance of an acceleration of rate during vagus stimulation is of interest.