Fig. 2. Differential interference contrast images of a Dictyostelium cell on the silicone substrate. (a) A single image of a cell surrounded with beads. (b) Five successive images acquired at 6 second intervals were superimposed, which clearly shows the movement of beads around the cell. Bar, 5 µm. Movie 1 showing cell migration on the silicone surface is available at jcs.biologists.org/supplemental.