T HE birth of modern local anesthesia took place with the demonstration by Keller of the anesthetic properties of cocaine in 1884, twenty-six years after it was isolated from the leaves of Erythroxylon coca by Niemann and Loessen. Alfred Einhorn in 1905 prepared Novocaine synthetically aft,er his discovery that local anesthetic action of cocaine is attributable to the combinstion of the benzoic acid radical and a basic nitrogen group. It was shortly after introduced into practice by Braun, who also, employing the principle suggested in 1885 by Corning, combined Novocaine with adrenalin, thus greatly multiplying its usefulness and creating the most satisfactory and least toxic of the many substitutes for cocaine. Novocaine, being entirely nonhabit forming, noncumulative, considerably less toxic than cocaine and any of its derivatives, possessing the highly commendable property of not causing tissue irrit,ation, when properly prepared and injected, being compatible with Adrenalin and readily soluble in isotonic salt solution, has practically fulfilled most of the principal requirements of an ideal local anesthetic agent. Since the discovery of Novocaine, a considerable number of substitute local anesthetics, mostly Novocaine derivatives were discovered, introduced, and tried, but because of one or more inherent faults, could not take thz place of Novocaine; their use was primarily limited either to direct application to sockets, burns, wounds, or ulcers, where the nerve ends may be exposed, or where surface or topical anesthesia is desirable. Among the principal reasons for the steadily continued search for a substitute for Novocaine remains the factor that while Novocaine, especially when it is combined with Adrenalin or some other vasoconstrictor, unquestionably possesses most of the requirements so highly desirable in a local anesthetic, it is equally true that it also lacks in some essential desirable qualifications. When it is used without being combined with a vasoconstrictor, its anesthetic property is quite ineffective, and when it is used with a vasoconstrictor, it not infrequently and unpredictably gives rise to various systemic side reactions. Its duration is brief for the more extensive surgical procedures