therefore, be eliminated, before such accident can be attributed to any other cause less simple and direct. The first criticism to be addressed to the "statistics" contained in Dr. Clarke's clinical chapter, is, that this necessary elimination has not been made, and one possible cause arbitrarily selected out of an entire group of known causes. As far as may be gathered from his book, Dr. Clarke's theory may be thus formulated. Two intense nervous actions cannot, without detriment, be sustained at the same time by the same organization. The mental labor demanded by school studies on the one hand, and the physiological process of menstruation on the other, are each connected with intense action of different parts of the nervous system. They are, therefore, incompatible with each other; and from the attempt to sustain them simultaneously, results, first, the imperfect accomplishment of each; second, the general exhaustion of the over-burdened nervous system. To this exhaustion is to be attributed the uterine haemorrhages upon which Dr. Clarke insists as the accident particularly liable to be induced by any continuous, _i.e._, non-intermitting, system of education. For non-medical readers it is important to develop the ellipsis and explain the facts upon which, if anywhere, this theory is based. The nervous system, though in many respects a unit, consists of two great sections, called respectively, the ganglionic system, and the cerebro-spinal; the latter formed by the brain, the spinal cord, and the medulla-oblongata, that connects them; the former, constituted by smaller masses of nervous matter distributed in three ways: First, in a double chain lying on each side of the spinal cord, from the upper part of the neck to the pelvic cavity that terminates the trunk. These masses are called especially the sympathetic ganglia. Second, in so-called plexuses, occupying different positions in the cavity of the trunk, and standing in especial relation to various organs; the solar or coeliac plexus to the stomach, liver, and spleen; the two renal plexuses to the kidneys; the mesenteric plexuses to the intestine; finally, on each side of the pelvis, the hypogastric plexus to the bladder, uterus, and ovaries--the so-called genito-urinary organs. Third, besides these principal ganglia exist others, much more minute, imbedded in the muscular walls of certain organs--as the heart (intro-cardiac ganglia), the intestine (intestinal ganglia).