DIURNAL CHANGES IN THE ELECTRICAL RESPONSE OF THE COMPOUND EYE

Abstract

1. A diurnal rhythm occurs in the electrical responses obtained from the compound eyes of certain beetles (Chlaenius diffinis, Chlaenius tomentosus, Hydrus triangularis, Harpalus caliginosus, Harpalus pennsylvanicus). When one of these beetles is kept in total darkness and under approximately constant environmental conditions, the electrical response to a brief exposure of light which is recorded during the morning and afternoon hours (day-type) is markedly different from the response obtained during the late afternoon and evening hours (night-type).2. The day-type of record is relatively simple and not unlike that which is always obtained from certain grasshoppers and butterflies. The night-type of response, always of greater magnitude, possesses a complex wave form similar in many respects to that always elicited from the eyes of certain moths.3. The day-type of response is reduced in magnitude but not greatly altered in form when the eye is light-adapted. The night-type of electrogram is not only reduced in magnitude by light-adaptation of the eye, but the wave form is markedly altered.4. The possibility is suggested that the diurnal cycle in the electrical response may be related to a diurnal migration of eye pigments.