It has been shown by Levy that cats under chloroform anesthesia are likely to develop extrasystoles of varying types, especially when the concentration of vapor is 2 per cent or less. The extrasystoles were found to be of all grades, from isolated ectopic beats to complete tachycardia of the ventricles. Levy and Lewis were of the opinion that this tachycardia passed readily into ventricular fibrillation. When the concentration of the chloroform vapor was greater than 2 per cent, the frequency of the appearance of abnormal ventricular beats was lessened, but with a vapor of 0.5 per cent the frequency of ventricular fibrillation was increased. Levy also found that, when epinephrine was injected intravenously into cats under light chloroform anesthesia, extrasystoles and ventricular fibrillation appeared within a few seconds. This observer showed that the lighter the anesthesia, the more readily did ventricular fibrillation appear after injection of epinephrine, but that with