Initiation of Circadian Rhythms in Arrhythmic Churchyard Beetles (Blaps mucronata)

Abstract

IN a recent article Brady¹ has drawn attention to the conflicting evidence on the physiological control of circadian rhythms in insects and concludes that the primary control is not hormonal but nervous. This conclusion is based in part on the failure of Roberts² and of Brady³ himself to repeat Harker's⁴ transplantation experiments in which the sub-oesophageal ganglia from rhythmic cockroaches elicited a rhythm in headless recipients. In Brady's work only two of forty-eight implanted animals subsequently became rhythmic. Similar results have been obtained by Fletcher⁵ using the churchyard beetle (Blaps mucronata). We have subjected arrhythmic beetles to transplantation of organs from rhythmic donors, and sundry other treatments.