Frank Mayer is a professor of microbiology at the Georg August University. He investigates the relation between structure and function of macromolecules in prokaryotes. He has authored or coauthored about 180 original papers and review articles and served as the editor or author for numerous book chapters and books in the field describing ultrastructural research. Address for both: Institut für Mikrobiologie und Genetik, Georg-August-Universität Göttingen, Grisebachstrasse 8, D-37077 Göttingen, Germany. Internet for Mayer: fmayer@gwdg.de