552 THE OUTGO OF ENERGY 



pulse wave is small and the upstroke slow, 

 corresponding to the small slow inflow through 

 the stenosed valve. 



Kestore the valve to its normal state. 



Incompetence of the Mitral Valve. Remove 

 the rubber flap from the mitral valve. Record 

 pulse curves as before. 



The pulse will be small, because the pressure 

 in the auricle (in this case the reservoir of water) 

 is always low, while the pressure in the arteries 

 is always high. Hence the ventricle will partly 

 empty itself through the incompetent mitral 

 valve, in the direction of low resistance, before 

 the pressure in the ventricle rises high enough to 

 open the aortic valve against the high aortic 

 pressure. The quantity remaining in the ventri- 

 cle when the intra ventricular pressure rises high 

 enough to open the aortic valve is not sufficient 

 to distend the arteries to the normal degree. 



In mitral stenosis the pulse is also small 

 because the narrowing of the mitral orifice per- 

 mits less than the usual quantity of liquid to 

 enter the ventricle. 



THE VOLUME PULSE 



Remove the receiving tambour of the sphygmo- 

 graph from its tube, and insert the plethysmo- 

 graph cylinder (this is the tube used in the 



