VELOCITY AND PRESSURE OF BLOOD-FLOW. 



451 



This fact is illustrated in Fig. 186, which gives a graphic represen- 

 tation of a number of experimental determinations (Dawson) of 

 systolic and diastolic pressures in the large arteries of the dog. 



If we turn to the other end of the vascular system, the veins, 



Fig. 186. Curve showing the results of actual measurement of systolic, diastolic, and 

 mean pressure (lateral pressures) along the aorta and femoral of the dog. The branches 

 through which the lateral pressures were obtained are indicated as follows: Sb, Left sub- 

 clavian; C-M, celiac and superior mesenteric; R, left renal; F, left femoral (Ellenberger 

 and Baum), external iliac; P, profunda branch of femoral; S, saphena. The pressure in 

 millimeters is given along the ordinates to the left. It will be noted that the mean and 

 the diastolic pressures remain practically the same throughout the descending aorta and 

 into the femoral. The systolic pressure shows a marked increase at the lower end of 

 the aorta and then falls off rapidly. The pulse pressure at the inferior end of the descend- 

 ing aorta is much larger than at the arch. (Dawson.) 



we find that the lowest pressure is in the jugular .and that it increases 



gradually as we go toward the capillary area. According to one 



observer,* the fall in pressure from periphery toward the heart is 



* Burton-Opitz, "American Journal of Physiology," 9, 198, 1903. 



