528 



Messrs. M. Flack, L. Hill, and J. McQueen. 



kidney, the length of artery being connected to the renal artery and the renal 

 vein to the outflow. 



The compression chambers being connected with each other, a part of the 

 pulsatile force transmitted through the artery to its chamber is conveyed to 

 the chamber of the tissue schema and helps to pulse fluid out of the tissue 

 schema. 



When decompression is begun the tissue schema is shrunken, and it takes 

 time to fill out. The outflow is in drops while the expansion is going on. 

 The pulsatile force transmitted through the artery to its chamber is now less 

 spent on the shrunken schema, for this is a more rigid structure. On the 

 other hand, the pulse transmitted directly along the artery to the tissue 

 schema spends part of its force in expanding the shrunken tissue schema. 

 So long as the tissue schema acts as a rigid structure and stores little of the 

 systolic force, the diastolic pressure in the artery will fall to lower level, and, 

 in consequence, the pulsatile swing will be bigger. 



The recorded pulse is the summation of that from either chamber, the 

 pulse of the artery, and of the tissue schema. 



There is a certain degree of expansion of the tissue schema, which favours 

 the development of a maximal pulse, the stage when the arterial pulse is 

 spent least on, and reinforced most by, the tissue schema. 



If the compression and decompression be done in stages, and time be 

 given between each stage for the tissue schema to shrink or expand, then 

 the maximal pulse occurs at the same height on decompression as on 

 compression. 



B. The share which the tissue schema takes in the phenomena is shown 

 in fig. 11. The artery was replaced by a rubber tube (rigid). On com- 

 pression the tissue schema shrank and gave a maximal pulse. On decom- 

 pression the tissue expanded, and the recorded pulse in this case became 

 smaller because the pulsatile force was spent largely on the expansion of 

 the tissue schema. 



Phenomena of the same order happen when the tissues of the arm are 

 compressed by the armlet, and hence arise those differences between com- 

 pression and decompression readings of systolic pressure which are so often 

 recorded. 



Experiment VII. 



The flow was through a length of artery and the tissue schema placed in 

 series (fig. 1). Each was in a separate chamber, and these were joined 

 together and to the compression bottle. The tube connecting the artery 

 and tissue schema was joined to the recording manometer. 



