INTRODUCTON A thorough consideration of the circulation of the blood in its relation to mental states reveals the fact that slight disturbances in the functioning of the circulatory organs may quite seriously affect consciousness. Mood in the brain of the requisite purity and rapidity of flow seems quite essential to normal consciousness. The lack of proper stimulation by a sufficient quantity of oxygenated blood will produce mental stupidity and coma. Any derangement of the functions of those organs of the body which in any way aid in contributing pure blood to the brain, may be said indirectly to affect mental states. All modern writers upon hygiene insist that for students to do the this work in school, pure air and plenty of exercise are essential, not only for health, but for efficiency in thinking. Scats and desks must be cornfortable, and of the propcr shape and height to keep the body in a position suitable for normal circulation of the blood and breath. If either are impaired, the attentive powers are distracted and conditions become lees efficient. Since this treatise deals with a comparison of activity in the horizontal and vertical positions of the body...