Circadian rhythmicity in the 'basal' pancreatic secretion of the domestic fowl.

The interdigestive pancreatic exocrine secretion of the domestic fowl has been studied following the cosine-vector analysis. For the flow of pancreatic juice the crest phase was at 1040 and the sample amplitude was 2.26 microliter/min. For the amylase output the crest phase was at 1128 and the sample amplitude was 0.297 U.A.A./min. Both parameters are characterized by a phase-and frequency-synchronized rhythm whose period must be close to 24 hr.