A great deal of work has been done within the last few years on the bactericidal effects of various antiseptics. A search of the literature, however, reveals little regarding the effects of these substances on living tissue. The criterion by which the efficacy of an antiseptic may be judged is twofold. Its bactericidal effect should be high, and at the same time it should have no injurious effect on the tissues to which it is applied. It is obvious that substances which are general protoplasmic poisons cannot fulfil the requirements for a perfect antiseptic. Many of these, however, have been used and have undoubtedly played an important part as a cause of delay in the healing of wounds. The perfect antiseptic should therefore have a specific action on bacteria, and be capable of acting efficiently in the presence of serum. The purpose of the present work is merely to develop