THE CIRCULATION 151 



appreciable interval. It is for this reason that the 

 radial pulse cannot be used in timing heart murmurs. 

 The less elastic the arteries are, the less is the delay in 

 the transmission of the pulse, and in cases of extensive 

 atheroma the delay may for this reason be very slight. 

 The actual time occupied by the pulse wave in passing 

 any point e.g., under the finger laid upon it depends 

 upon the resistance it has to overcome from in front. If 

 the arterioles are contracted the resistance is great, and 

 the pulse passes slowly, and in clinical language it is 

 spoken of as a long pulse; on the other hand, if the 

 arterioles be dilated so that blood escapes easily into the 

 capillaries, the wave sweeps on rapidly and the pulse is 

 short. In other words, a ' long ' pulse is characteristic 

 of high tension in the arteries, and a ' short ' pulse of low 

 tension. 



We may sum up the characters of the standard or 

 typical pulse of the adult male in the words of Broad- 

 bent,* as follow : 



'It will have a frequency of seventy -two beats 

 per minute, will be perfectly regular in time, and 

 the beats will be of equal force. . . . The individual 

 pulse waves reach the finger nearest the heart with a 

 definite stroke, which can scarcely be described as 

 sudden, still less as sharp; they have sufficient vehe- 

 mence to be felt by all three fingers, unless decided 

 pressure is made on the vessel, but they can be arrested 

 without difficulty by one finger, the beat feeling then 

 both more sudden and more vehement. The wave of 

 expansion or distension of the artery does not instantly 

 * ' The Pulse,' p. 46. 



