twenty-four hours; but that the head, being rigid, would often prove too large for the mouth of the trap and would remain outside, plugging the door. When this happened, the trap evidently formed an effective seal with the head of the larva as it could still excrete water and become flattened, but it would nevertheless die within about ten days "evidently due to overfeeding". Softer-bodied prey of the same size such as small tadpoles could be ingested completely, because they have no rigid parts and the head, although capable of plugging the door for a time, will soften and yield and finally be drawn in. Very thin strands of albumen could be soft and fine enough to allow the trapdoor to close completely; these would not be drawn in any further unless the trigger hairs were indeed stimulated again. On the other hand, a human hair, finer still but relatively hard and unyielding, could prevent a seal being formed; these would prevent the trap from resetting at all due to leakage of water. Lloyd concluded that the sucking action produced by the excretion of water from the bladder was sufficient to draw larger soft-bodied prey into the trap without the need for a second or further touch to the trigger levers. An animal long enough not to be fully engulfed upon first springing the trap, but thin and soft enough to allow the door to return fully to its set position, would indeed be left partly outside the trap until it or another body triggered the mechanism once again. However, the capture of hard bodies not fully drawn into the trap would prevent its further operation. Genetics Chris Whitewoods has developed a computational model of possible genetic regulation in Utricularia gibba to show how genes may control the formation of the upper and lower surfaces of flat leaves and how cup-shaped traps may have evolved from flat leaves. Changes in the gene expression of Utricularia can explain these structural changes. U. gibba leaves appear similar early in development but may develop into either a spherical trap or a cylindrical leaflet at later stages. Directional expansion of the leaf is suggested to be a crucial driver of the trap's morphogenesis. The upper and lower faces of the leaf are differentially associated with genetic markers. The marker UgPHV1 is associated with the upper leaf face. Trap primordia become spherical in shape, due