The aim of these investigations was to determine the degree of applicability to single muscle fibers of certain concepts derived primarily fro,m the study of nerve. I n addition, it was desired to see whether the appearance of repetitive cathodal closing responses and anodal opening responses in muscle were related to the area of membrane depolarized, particularly considering the role of the ' ' accommodative ' process.
That sciatic nerves of "citrated" frogs possess little or no accommodation at large and indefinitely localized cathodal areas and considerable accommodation at sharply localized small cathodal areas has been noted previously (Benoit and Benoit, '37). Similarly, Suzuki ( ,38) reported that the value of the time constant of accommodation, A, was greater at a large fluid electrode than it was at a punctate cathode. Benoit ('49), working on frog sartorii, was able to show that diffuse cathodal stimulation favors repetitive responses, while stigmatic cathodal sti'mulation favors simple twitch responses.
Thus it was decided to test the basic contention that prolonged convergent current flow in an excitable tissue favors accommodation. The use of the single muscle fiber prepara-