1 This symposium was held at the Fifty-seventh General Meeting of the Society of American Bacteriologists in Detroit, Michigan, on May 2, 1957. John Gavin, Chairman of the Committee on Analytical Microbiology, was the organizer. Participants were: Edward W. Toepfer and Howard Reynolds (represented by Thomas P. O'Barr), Food Analysis Section, Human Nutrition Research Branch, United States Department of Agriculture, Washington, D. C.; Alphee E. Tanguay, Lederle Laboratories, Pearl River, New York; and Lawrence J. Dennin, Eli Lilly and Company, Indianapolis, Indiana.