Video: Bacterial Colony (1 of 2) (video) Duke University Loading video... Caption Growth of a bacterial colony (green) over about 60 hours is shown. The blue "on" signal spreads outward from the center; red represents the "off" signal triggered over time. Credit Stephen Payne, Duke University Usage Restrictions None 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.