224 ANIMAL PHYSIOLOGY. 
departure from this harmony of rhythm would lead to serious 
disturbance. 
Capillaries of the 
ead, ete. 
Pulmonary Capil- 
laries. 
Superior Vena Cava, 
Inferior Vena Cava. 
Main Arterial Trunk. 
Capillaries of Liver. 
Portal Vein. 
Capillaries of 
Splanchnic Area. 
Capillaries of Trunk 
and Lower Ex- 
tremities. 
Fie. 204.—Diagram of the circulation. The arrows indicate the course of the blood. Though the 
pulmonary and the upper and the lower parts of the systemic circulation are represented 
so as to show the distinctness of each, it will be also apparent, that they are not independ- 
ent. Relative size of different parts of the system is only very generally indicated. 
THE VELOCITY OF THE BLOOD AND BLOOD-PRESSURE. 
If the relative capacity and arrangement of the various 
parts of the circulatory system be as has been represented, it 
follows that we may predict with some confidence, apart from 
experiment, what the speed of the flow and the vascular ten- 
sion must be in different parts of the course of the circulation. 
We should suppose that, in the nature of the case, the ve- 
locity would be greatest in the large arteries, gradually dimin- 
ish to the capillaries, in which it would be much the slowest, 
and, getting by degrees faster, would reach a speed in the largest 
veins approaching that of the corresponding arteries. 
