THE MOLECULAR BIOLOGY OF PLAGUE TOXIN11The early part of this work was done while one of the authors (S.J.A.) was a member of the Walter Reed Army Institute of Research in Washington, D.C. This work has been continued at the Albert Einstein Medical Center in Philadelphia. The bulk of the work described has been supported by grant GB-2405 from the National Science Foundation to Dr. Solomon Kadis and by grant AI-03866 from the National Institutes of Health to Dr. Samuel J. Ajl.