Increased pulse pressure therefore goes hand in hand with greater systolic output. Physiologically this is most ideally seen during exercise. Following exercise the pulse rate increases, the systolic pressure rises greatly, the diastolic slightly or not at all. The pulse pressure therefore is increased. The velocity also is much increased. The call comes for more blood and the heart responds. In the chronic high pulse pressures there are four correlated conditions which, so far as I have studied them, are always present. These are: (1) An increase in size of the cavity of the left ventricle. The ventricle actually by measurement contains more blood than normal, and therefore throws out more blood at every systole. The volume output is greater per unit of time. (2) There is actual permanent increase in diameter of the arch of the aorta. This is a compensating process to accommodate the increased charge from the left ventricle. (3) There are on careful auscultation over the manubrium, particularly the lower half, breath sounds which vary from bronchial to intensely tubular, depending upon the anatomic placing of the aorta, the shape of the chest, and the degree of dilatation. Often there is very slight impairment of the percussion note as well. (4) There is increase in size of all the large distributing arteries, carotids, brachials, femorals, renals, celiac axis, etc., with fibrous changes in the media, loss of some elasticity, and increase in size of the pulse wave. Increased pulse pressure means increased volume output, but does not always mean increased velocity. The proper distribution of blood to the various organs of the body is regulated by the vasomotor system acting upon the small arteries which contain considerable unstriated muscle. When fibrous arteriosclerosis is present there is loss of elasticity in the distributing arteries and a greater volume of blood must be thrown out by the ventricle at every systole in order that every organ shall have its full quota of blood. A force which is sufficient to send blood through elastic normal distributing tubes becomes totally insufficient to send the same amount of blood through tortuous and more or less inelastic tubes. It is evident then that pulse pressure is exceedingly important. It can only be determined by measuring both the _systolic_ and _diastolic_ pressure. The pulse rate must also be known in order to compute the velocity. It is essential to have the whole pressure picture for all cases if correct conclusions are to be drawn.