or conditions. Broad gauge openminded observation, thorough study of all facts or conditions reasonably considered likely to prove salient, definitebut duly elastic-long-pull program planning, and organized effort now are needed to give promise of satisfactory accomplishment in this as in many other lines of scientific endeavor. Old tilled fields must be resurveyed, new unbroken fields explored, and every trail followed until found false, promising, or true. The epidemiological studies of tuberculosis inaugurated by the U. S. Public Health Service and conducted intensively since July 1, 1936, with the cooperation of the State Health Departments of Alabama and Tennessee, the