An experimental study has been made of boundary conditions at the positive end of positive columns in neon which were traversed by waves of ionization (moving striations) proceeding towards the Faraday dark space. The striations were generated from small anode spots, which usually oscillated with increasing amplitude until they became detached from the anode. Closely similar processes took place at the negative end of a capillary tube when the discharge was passed through the capillary into a wide tube. A few typical time-resolved photographs of the oscillations have been reproduced to illustrate the nature of the phenomena and their dependence on pressure and current, and possible causes of the oscillations are discussed briefly.