The Measurement of Arterial Pressure in Man. 533 



the labile artery (fig. 19). That this is so is shown by the fact that a like 

 result is obtained when a piece of rubber tube (rigid) is substituted for the 

 artery and the compression chamber is left open. 



Off. On. 



Fig. 18. 



Off. 



On. 



Fig. 19. 



When the kidney is compressed the pressure rises and the pulse recorded 

 by the manometer becomes increased still more. The explanation is as 

 follows : — 



The kidney shrinks and the resistance to the flow through its vessels 

 increases. The renal vessels become rigid and no longer store up the systolic 

 pressure. The diastolic pressure falls in consequence, and the full swing of 

 the pulse is thrown upon the manometer. 



Experiment XII. 



The flow was through the two complete schemata placed in series, and 

 each in a separate compression chamber (fig. 2). The compression chamber 

 of schema II was connected to the manometer. 



Fig. 20. 



2 T 2 



