Biological Rhythms (IMAGE) Rockefeller University Caption As part of studies of the circadian clock, Kidd and others in the lab put fruit flies in glass tubes to monitor their daily activity. The molecular basis for the flies' clock is well understood, but the reason its 24-hour period does not lengthen or shorten with temperature is a long-standing mystery. Credit Zach Veilleux/The Rockefeller University Usage Restrictions Image may only be used to illustrate the research described in the accompanying release. License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.