CROSSING OF DISCLINATIONS IN NEMATIC SLABS

It is shown experimentally that crossing and intercommutation of discl inations in a bounded nematic cell depend on surface orientation of th e director and the relative strength of disclinations. Lines of opposi te strength switch the pinned ends between the bounding plates and van ish independently of each other if the surface orientation is tangenti al. In contrast, tilted surface orientation preserves the stability of lines.