English: Surface Properties Alter Self-Aggregation Dynamics. Representative time-lapse movie of WT cells aggregating on each of the four surfaces, as filmed by dark-field microscopy. Each second represents one hour of aggregation, for a total of 6.5 hours. On BSA the aggregation process involves large streams, and on PLL and FCC aggregation involves cells clumping into small groups, which in turn coalesce into larger groups. Aggregation on glass is between these two extremes. Scale bar = 1 mm.