Beta-aminopropylbenzene (benzedrine) is a compound of the epinephrine series resembling ephedrine in chemical constitution, as shown in the structural formula. In 1910 Barger and Dale1made an exhaustive study of a large group of epinephrine-like substances, with the conclusion that an action simulating that of true sympathetic nervous stimulation is not peculiar to epinephrine but is possessed by a large number of amines (substituted ammonias). These substances were termed sympathomimetic amines by Barger and Dale, since they mimic the effects of sympathetic stimulation. The response of the blood pressure in experimental animals has been used largely to study the comparative activities of these compounds. More recently I have studied the comparative actions of these substances on the cardiac standstill which may be induced in many individuals by pressure over the carotid artery in the neck.2 Interest in these compounds has centered almost entirely on the sympathomimetic action, an