I. INTRODUCTION. The consideration of certain proprietary "internal antiseptics" by the Council on Pharmacy and Chemistry revealed important discrepancies between the claims of the manufacturers and the results obtained by other investigators with analogous products. It appeared to me that a fair disposition of the questions thus raised could only be obtained by a direct experimental investigation, which I, therefore, undertook. I also believed it worth while to compare the antiseptic value of these products with those of the older and better known drugs. In the determination of the antiseptic value I have departed from the ideal, but highly artificial, conditions of the customary culture experiments, and have aimed to reproduce, so far as possible, the conditions under which the drugs are actually used. Exception may, of course, be taken to the application of any laboratory experiments to clinical problems; but until a clinical method of comparing antiseptic values is