An investigation has been made of certain phenomena associated with space charge external to the grid which surrounds the cathode in a multi‐grid tube. This paper reports a new effect, the essential feature of which is a negative plate current‐emission characteristic. The conditions under which this phenomenon is observed are outlined. Results of experiments with double and triple grid tubes are summarized. In general, two points on the characteristic may be found for which the plate current is independent of small variations in emission, whether of a statistical or ``functional'' nature. An explanation is presented based on the interaction of multiple space charge. An application to the problem of high gain amplification is suggested.