In a very important series of experiments on prisoners, MacGilchrist found that hydroquinine (a synthetic product of quinine) was about 20% more efficient than quinine. Cinchonine was about the same as quinine while quinidine was about one-half as potent as quinine. Acton has praised the value of cinchona febrifuge (the combined alkaloids of cinchona) given in daily doses of 21 grains for ten days. Methods of Administration _By Mouth._—This is the usual method and is the one to be preferred in all cases where other methods of administration are not necessitated. Golgi believes that quinine is most effective at the time of liberation of merozoites from the bursting merocytes, hence he administered quinine four hours before the attack with a view to having it in its greatest concentration in the blood at such times. When given intravenously the full concentration is obtained in a very few minutes but with other methods this is a matter of great variation. It is usual to give the quinine in capsules or cachets, the pills and tablets being often so hard that they do not dissolve in the alimentary tract. The method usually in vogue in military services is to give quinine sulphate in acid solution. This method is trying to the stomach. _By Subcutaneous Injections._—This method is liable to be followed by necrosis and abscess formation or fibrous indurations. Quinine and urea hydrochloride is preferable either for subcutaneous or intramuscular injection. Cohen holds that quinine and urea hydrochloride controls malarial infection more rapidly and efficaciously than any other salt of quinine when given intramuscularly. In order to prevent tetanus or other infections he is very careful about asepsis. He recommends that a 10 to 15-grain dose be injected every day for a week, then once a week for a month, then once every two weeks for another month. He considers a 33% solution as best, thus one could give 10 grains in the contents of an all-glass 2 cc. syringe. James has recommended very dilute solutions for subcutaneous injections (1-150). There are practical objections to this method. It is usual to give about 1 gram (15 grains) of a soluble salt in 10 cc. of water. _The present view is that subcutaneous injections deserve condemnation._ _Intramuscular Injections._—It is now recognized that when quinine is not well borne when given by mouth the two modes of administration to be followed are either by intramuscular injection or introduction of the drug into a vein. For intramuscular use we dissolve a soluble salt of quinine, as the bimuriate or chlorhydrosulphate, in distilled water or sterile saline. A 50% solution is commonly used and from 6 to 10 grains of quinine is injected into the gluteal muscles of one side about 3 inches below the iliac crest. Repeat the injection on the other side. Repeat this daily dose of 12 to 20 grains for 3 or 4 days; then give quinine by mouth.