 By developing a membrane-based microfluidic device suitable for culturing a large cell population under uniform and controllable growth conditions, we study how the cell size distribution changes after the supplied medium is switched from a nutritious to non-nutritious one, triggering the bacterial reductive division . The mean cell size then gradually decreases, but we find that the size distribution is kept unchanged if the cell sizes are normalized by their time-dependent mean value ;
<clarity>  By developing a membrane-based microfluidic device suitable for culturing a large cell population under uniform and controllable growth conditions, we study how the cell size distribution changes after the supplied medium is switched from a nutritious to non-nutritious one, triggering the bacterial reductive division . The mean cell size then gradually decreases, but we find that the size distribution is kept unchanged if the cell sizes are normalized by their time-dependent mean value ;
 By developing a membrane-based microfluidic device suitable for culturing a large cell population under uniform and controllable growth conditions, we study how the cell size distribution changes after the supplied medium is switched from a nutritious to non-nutritious one, triggering the bacterial reductive division by switching to non-nutritious medium, we find evidence that the cell size distribution changes in a specific manner that keeps its normalized form unchanged ;