The Role of Bacteria in the Formation of Free Fatty Acids on the Human Skin Surface**From the Section of Dermatology, Department of Medicine, The University of Chicago, Chicago, Illinois.This work was supported in part by the Research and Development Division, Office of the Surgeon General, Department of the Army, under contract No. DA-49-007-MD-411, and in part by Public Health Service Grant E-1444(C3).This work was begun with the cooperation of Dr. N. Nicolaides. He reported on our initial results in closing the discussion of his presentation in the Society of Investigative Dermatology in 1957. See reference No. 2.