The Electrical Properties of Frog Skin

THIS paper is the first of a series in which the results of a study of the electrical properties of frog skin will be presented. Frog skin is a convenient material for bio-electric investigation. It is easily obtained, can be mounted as a membrane and gives high potentials (ca. 40—70 millivolts between opposite sides of the skin). On the other hand the complexity of structure of the skin tissue makes it difficult to determine which cells are the seat of the potential. Considerable insight has, however, been gained during this work into the chemical and physical processes by which the electrical potential is maintained. This is of interest in relation to the general problem of the nature and origin of bio-electric potentials. The skin of the frog has a respiratory function (Krogh, 1904) and also serves to maintain a water equilibrium between the animal and its surroundings (Adolph, 1925). The existence of the frog skin potential has been known since 1857 and the literature summarised by Orbeli (1910). Much of the work has been done with preparations of the whole animal and is concerned with the nature of the response of the potential to stimulation of the nerve supply. In the following work only the steady resting potential is considered and the skin is separated from the frog before the experiment begins.