Several investigators have recorded electrocardiograms on the embryonic chick, and, in the recent report of Sands, a monophasic tracing was obtained at the 35th hour of incubation. A typical rapid initial ventricular phase and slow final phase, i. e., Q-R-S and T deflections were not obtained until between 50 and 72 hours. It has been determined by Duval and others recently that ingrowth of nerve fibres does not take place until approximately the 6th day, but that the heart generally starts beating at the 10 somite stage or about 29 hours. We attempted to obtain electrical records of the heart activity, using German silver electrode contacts along an approximate axial lead of the heart. A resistance coupled tube amplifying mechanism, the Nichols-Chase electrocardiograph apparatus, was used for amplifying and recording the action currents in most of the embryos. The Einthoven string galvanometer was occasionally employed on the older preparations. Digitalis in an aqueous solution, as Digifoline, Ciba, equivalent to 0.1 digitalis leaf per cc. was applied directly to the exposed pulsating heart without changing the electrodes. Variations of temperature were difficult to control, but the surface was kept moist with water approximately at 37°C. Adrenalin and other drugs were applied, but the results of these applications will be reported at a later date. The records obtained showed a multiphasic curve similar to an adult type electrocardiogram as early as the 35th hour of incubation, an embryo of 12 somites. Digitalis caused a definite change in the form and direction of the final or slow phase of the ventricular deflection. The electrical potential developed was approximately 0.5± millivolts.