In recent years there has been a decided tendency toward interest in the subject of low blood pressure, perhaps because some of us are tired of the question of high blood pressure. The present book was written in the hope of presenting this subject from a broad biologic point of view. The general discussion of the physiologic significance of blood pressure is excellently given; then the author proceeds to the question of low arterial pressure, particularly in regard to its etiology. The standpoint is taken that patients with low arterial pressure may be considered as having a low vitality secondary to constitutional or to nutritional disorders or disturbances of the endocrine glands. It is assumed that a change occurs in the "acid-base tissue balance," so that these patients are much more likely to have a high ratio of alkali to acid in the urine. This biochemical change is given considerable