+Endermically.+ The endermic method is the one most generally employed in securing cocaine local anesthesia by injection. The papillary layer of the skin is well infiltrated with a mild solution (one-eighth per cent. to one-half per cent.), frequently with adrenalin 1-1000, in the proportion of 15 to 20 drops to the ounce of the solution. The strongest of the formulas of Schleich may also be used for endermic infiltration. The skin is injected to a fair degree of tension and a white ridge marks the line of injection which should be sufficiently extensive to permit the manipulation of the cut edges. +Edemitization.+ Schleich’s solutions are here of extreme value because large amounts of solution are necessary to produce the degree of distention required because of the minute quantity of cocaine present, though the added salt and morphine assist considerably. +Nerve Blocking and Perineural Blocking.+ Here a stronger solution must be employed; 1 per cent., or even stronger, is injected in small quantities, either into the substance of the nerve or under its sheath, as already described. +Strength of Solution.+ Schleich has worked out a method whereby very weak solutions of cocaine may be used advantageously. His plan is to enhance the action of the drug by the admixture of morphine in minute quantities and of sodium chloride in proper strength. These substances, in themselves, were found to possess anesthetic powers. Large quantities of Schleich’s solutions may be injected—even several ounces, without ill effects as they contain so little cocaine. The formulas used by him are: 1. Cocaine hydrochlorate 0.2 Morphine hydrochlorate 0.02 Sodium chloride 0.2 Distilled water 100. 2. Cocaine hydrochlorate 0.1 Morphine 0.02 Sodium chloride 0.2 Distilled water 100. 3. Cocaine hydrochlorate 0.01 Morphine 0.005 Sodium chloride 0.02 Distilled water 100. It will be seen that the strength of cocaine in the respective solutions is from one-fifth to one-hundredth of a gram. The solutions used in the early days of cocaine anesthesia were much stronger than were found necessary afterward and it has now become the rule to employ weak solutions and to give them time to penetrate the tissues. The less toxic action of mild solutions, even when like amounts of the drug are employed, makes it incumbent upon the operator to follow this plan and the element of time is so important in the matter of securing a perfect local anesthesia that it is customary to wait fifteen or twenty minutes after the completion of the injection before making the incision. The weakest solution possible is the one of choice in the use of this anesthesia.