In the transition region between glow and arc discharges with a heated tungsten cathode in argon at 500 torr, the series of current-voltage characteristics with the cathode temperature T_c as parameter show three types of discharge mode:T_c <or= 2280°K: a mixed glow-arc type results.T_c > 2280°K: the electron space charge intervenes, and only a glow mode exists. Elimination of the cathode fall is complete at 2600 < T_c < 2800°K. Glow-arc-glow transients result from variation of the electronic space-charge density and are a function of anode voltage, revealing mass acceleration by an electric field. Graphical analysis shows a multiplication of charge carriers, not exceeding a factor of approximately 2, occurring over a distance of about 1·4 × 10^-3 cm and caused by a field of about 10⁵ V cm^-1.T_c > 2700°K: gas convection interferes with the motion of the positive ions, and reduces the current in the glow.