Figure 3.

A droplet shown during collapse of the masked area. As in Figure 1, a triangular edge mask kept an unphotolyzed reservoir of COHbS adjacent to a region polymerized by photolysis. After 71 minutes, the hemoglobin in the reservoir flowed to the perimeter, and we interpret this as due to the outward pressure of the fibers against the surface. A bubble forms first because the edge of the droplet is pinned. Conditions otherwise are as in Figure 1.