The usual augmenting action of pressure on the tension developed by striated muscle in response to a single stimulus changes to depression on fatiguing the muscle. On release of the pressure the tension of the single twitch again reaches the control value. A similar reversal may be brought about by cooling the muscle, the change usually occurring at about 13 degrees C. Below this temperature the depression is roughly proportional to the pressure. At about 1 degrees C. the tension development may be completely inhibited by high pressure. The muscle responds normally upon release of the pressure, and upon warming pressure again causes augmentation of contraction.