Blood borne factors in circadian rhythms of activity

Abstract

Rhythms of a circadian nature in locomotor and other kinds of activity have been described in a variety of organisms. While much is known about the time course and phase relations of such rhythms, very little is known about the internal regulating mechanisms. The diurnal locomotor rhythm in the cockroach is controlled by neurosecretory cells located in the sub-oesophageal ganglion. Transplantation experiments have shown the importance of the presence of the sub-oesophageal neurosecretory apparatus for the persistence of the locomotory rhythm, but no variations with the time of the day in the direct effects of the neurosecretory products on the degree of activity of the central nervous system have been demonstrated.