X. On the action of the excised mammalian heart

Abstract

Our attention was directed to the action of the excised Mammalian heart in the course of experiments relating to the electromotive action of various tissues, by our observation of the fact that the electromotive variations indicative of action outlast visible contractions; secondly, that the contractions of the excised organ are of an extraordinarily prolonged character. We consequently pursued our observations (1) by the galvanometer, (2) by the aid of the graphic method, (3) by the capillary electrometer (Lippmann). By the galvanometer and by the electrometer we observed the electrical changes consequent upon spontaneous or provoked contraction, and in the absence of visible contraction. By the graphic method we determined the duration of spontaneous and of excited beats, and, with regard to the latter, the length of the latent period at various times after excision. Incidentally we also observed the time during which the rhythmic beat persisted after excision and the character of that beat under varying conditions of temperature. By both methods we were able in favourable cases to follow the progress of the wave of contraction, both spontaneous and excited. Our observations were made on the hearts of Cats, Bogs, Rabbits, Guinea-pigs, Rats, and Sheep.