On Galvanotropism and Oscillotaxis in Fish

Abstract

A spinal fish bends with the concave side towards the anode in a D.C. field of transverse direction. This reaction, which lasts as long as the current passes, is shown to be a reflex (galvanotropic reflex). Other manifestations of this reflex have been found. In a field of dorso-ventral direction the animal is bent in the sagittal plane towards the anode. The unrest of body and tail in an ascending field in the longitudinal direction of the fish may be caused partly by the same reflex. The same reflex has also been found in some of the fin muscles. The structures (sensory end-organs) stimulated during the galvanotropic reflex are situated in the muscles (or tendons). Galvanotropism has been demonstrated in fish in which the labyrinths and the lateral-line organs have been eliminated by the transection of their nerves. The mechanism of galvanotropism is discussed and this phenomenon is found to be based on the galvanotropic reflex and the ability of the animal to swim. A fish placed at 45° to the current lines in an A.C. field shows a curving of the body and tail. This is explained by the wedge shape of the fish body and tail, by which the two sides of the animal have a different angle with the current lines, and thus are differently stimulated. The mechanism of oscillotaxis is discussed in relation to this reaction.