ON THE ARTERIES. 355 



powerful action of the ventricle ; the second is a 

 contraction of the artery, somewhat similar, ex- 

 cited by its distention : the third, though a pro- 

 perty independent of life, is a power permitting 

 no interval or alternation ; it is the elasticity of 

 the coats of the artery : and these three powers, 

 duly adjusted, keep up a continued stream in the 

 blood-vessels. It is true that when an artery is 

 wounded, the blood flows in pulses ; but that 

 proceeds from the regular acceleration of a jet 

 which yet has no actual interruption. Were not 

 this continued flow of the blood provided, there 

 would be a loss of power, at each pulsation of the 

 heart, in carrying the blood from a state of rest 

 to a state of motion ; and if we consider how 

 many pulses there are in the twenty-four hours, 

 80,000, we may make some estimate of the loss 

 of vital power that would accrue had there been 

 a neglect of the law of inertia in the apparatus 

 of circulation. 



