It is a common statement that because of its simplicity the bacterial cell makes an ideal model for the study of a wide variety of biological systems and phenomena. While no-one would dispute that much of our under standing of biological function derives from the study of the humble bacterium, the concept of a simple life-form would be hotly disputed by any scientist engaged in the determination of the relationship between structure and function within the bacterial cell. Bacteria are particularly amenable to intensive study; their physiology can be probed with powerful biochemical, genetical...