Attention has been called to the normal systolic pressure at different ages. This is not the only cause for variations in the blood pressure. Normally, it is greater when in the erect position than when seated, and greater when seated than when lying down. During the day there are well-recognized changes. The pressure is lowest during the early morning hours, when the person is asleep. In women there are variations due to menstruation. Muscular exercise raises the blood pressure markedly. The effect of a full meal is to raise the blood pressure. The explanation is that during and following a meal there is dilatation of the abdominal vessels. This takes blood from other parts of the body, provided that the other factors in the circulation remain constant. A fall of pressure would necessarily occur in the aorta. To compensate for this, there is increased work on the part of the heart, which reveals itself as increased pressure and pulse pressure. It is well known that the interest in the process taken by an individual upon whom the blood pressure is estimated for the first time tends to increase the rate of the heart and to raise the blood pressure. For this reason the first few readings on the instrument must be discarded, and not until the patient looks upon the procedure calmly can the true blood pressure be obtained. As a corollary to this statement, mental excitement, of whatever kind, has a marked influence on the pressure. The patient must remain absolutely quiet. Raising the head or the free arm causes the pressure to rise. Another important physiologic variation is produced by concentrated mental activity. This tends to hurry the heart and increase the force of the beat. In short, it may be stated as a general rule that any active functioning of a part of the body which naturally requires a great excess of blood tends to elevate the blood pressure. At rest the pressure is constant. Variations caused by the factors mentioned act only transitorily, and the pressure shortly returns to normal. =The Auscultatory Blood Pressure Phenomenon=