By a series of 31 experiments on 12 healthy young women it was determined that the rise of metabolism due to tilting the subject to 62[degree] was practically negligible while circulatory adjustments in heart rate and arterial pressures were almost as great as when the subject stood. The rise in metabolism in quiet standing was 19%, a rise which considered as exercise would by no means account for the marked increase in heart rate. A distinct reflex for the response to gravity as contrasted with exercise is thus suggested, though both are characterized by increased heart rate. Exercise shows a widened pulse pressure, standing a narrowed pulse pressure. A second series of 26 experiments on 12 subjects verified the general circulatory findings of series I but the omission of the movements attending the metabolism determinations revealed a difference in the gravity reaction for 60[degree] and for 90[degree]. The delicacy of the reaction of the circulatory apparatus to gravity for short periods of 6 min. was further tested by series III, 17 experiments on 11 subjects, in which the response to tilting, head up, to each of the following angles, 15[degree], 30[degree], 45[degree], 60[degree], 75[degree], 90[degree], was found to be distinct and progressive for both increase of heart rate and narrowing of pulse pressure. Preliminary experiments indicate that whereas the reaction with head up leads to higher heart rate and narrowed pulse pressure, the opposite is true for short periods in the head down position, decreased heart rate and widened pulse pressure. The progressive increase in the volume of the legs to a point above the knees was determined by standing in a can of water for 15 min. to average 175 cc. for series IV, 35 experiments on 20 subjects in the winter season, and 256 cc. for series V, a short series of 6 experiments on 4 subjects in summer. Series IV gave an increase of 1.9% in leg volume, series V an increase of 3.36%. This increase in volume may be explained by the stagnation of circulating liquids in the legs during quiet standing. That stagnation of blood occurs in the abdominal region during quiet standing is indicated by series VI, 16 experiments on 16 subjects, and by series VII, 13 experiments on 13 subjects. In each experiment circulatory determinations were made during a 15 min. period of quiet standing with no abdominal support and for a similar period with the firm support of corset or bandage. The response was markedly affected by the support, in that the rise of heart rate and the narrowing of pulse pressure were less than in the control experiments. Such changes are explained by the prevention of blood stagnation by the support and the consequent lessened need for adjustment because of better return to the heart than when the abdomen has only the usual muscular support.