THE CIRCULATION OF THE BLOOD 543 



Ordinarily the ratio between the blood-pressure 

 in the pulmonary artery and right ventricle so 

 nearly equals the ratio between the blood 

 pressure in the aorta and left ventricle that the 

 semilunar valves in the pulmonary artery and 

 aorta close together, or nearly together, and their 

 respective sounds are heard as one. Pathologic- 

 ally, for example in distention of the right heart 

 from prolonged violent exercise, these relations 

 may be so altered as to produce between the two 

 sounds an interval perceptible to the ear. The 

 sound is then said to be reduplicated. 



THE PRESSURE-PULSE 



Frequency. Palpate the radial pulse by 

 laying on the artery at the wrist the ball (not 

 the tip) of the first, second, and third fingers of 

 the right hand. The forearm of both subject 

 and observer should be supported in a comfort- 

 able position. Count the pulse in four successive 

 periods of fifteen seconds. The counting of the 

 observer's instead of the subject's pulse may be 

 avoided by noting whether the subject's supposed 

 pulse is synchronous with the observer's heart- 

 beat. 



Note the frequency per minule when the sub- 

 ject is standing, sitting, lying, swallowing, hold- 

 ing the breath ; and before and after exercise ; 



