Why the Constant Volume Rule Works (video) Washington University in St. Louis Share Print E-Mail Loading video... Caption By adding a constant volume before they divide, randomly sized bacteria quickly approach a common size. In this example, a cell that is bigger than average arrives at the common size in only a few replications. Credit Jun Lab Usage Restrictions Please credit the lab Share Print E-Mail 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.