The rates of reaction and reaction mechanisms in biological systems are the controlling factors in the metabolism and life cycles of all living organisms. Nevertheless, very little is known today about the details of these processes, particularly in more complicated life forms. For example, addition of certain metallic ions to an enzymic matrix can cause gross changes in enzymic activity (Brewer & Weber, 1966); just how these ions specifically enter into enzymic reactions is a subject of intense interest. The nature of the kinetics of bonding in nucleic acids is also the subject of much research (Eigen, 1967).

As is well known, the memorable discovery of Galvani (1791) was followed by the development of two new fields of science, electrochemistry and electrophysiology. During the course of this development, the most remarkable feature of the original finding, i.e. ‘contraction of muscle induced by a piece of metal’, gradually came to be ignored. As a consequence, the simple question as to how electrical stimulation might induce muscle contraction was left unanswered until the middle of this century, when several physiologists became aware of the crucial nature of the problem and tried to attack it from various directions. This resulted in a marked progress of physiological and morphological studies which were intentionally or unintentionally concerned with the mechanism of the link between excitation, that is the electrical phenomenon at the surface membrane, and the contractile process.