Histograms of cell area, and speed, for each fate and generation.

<p>Cell areas and speeds are computed as mean values over the lifetime of each cell. Since the total number of cells in each category varies, values shown are proportions of category total. Figures A and C show histograms of area, and figures B and D show histograms of speed (motility). These results suggest that cells fated to divide tend to move more slowly with each successive generation, and that cells fated to die tend to move more quickly than cells fated to divide. As expected, cells fated to divide tend to be smaller with each generation of division, but the relationship between area and fate is less clear for cells fated to die. In some generations dying cells' size follows an unexpected bimodal distribution. It is possible that the bimodal results are a consequence of systematic segmentation bias caused by intensely fluorescing dying cells (see section 2.4).