The Resonance of the Tissues. 



257 



beneath the bag, and there can be no loss of pressure here through the faulty 

 transmission of intervening tissues or through distortion" of tissues. 



Analysed anatomically position II is similar to position I, while in 

 position III the radial artery courses over the pronatus quadratus and flexor 

 longus pollicis. At position IV the brachial artery lies on the deep tendon 

 of the brachialis anticus muscle. 



Taking readings of disappearance and reappearance of the pulse with the 

 pocket sphygmometer we find — 



mm. of Hg. mm. of Hg. 



Position I pulse disappearance 55 pulse reappearance 50 

 Position II „ „ 55 „ „ 50 



Position III „ „ 130 „ „ 125 



"A „ „ 105 „ „ 100 



B „ „ 75 „ „ 70 



Position IV 



Substituting a bag of water for one of air the readings are — 



mm. of Hg. mm. of Hg. 



Position I pulse disappearance 55 pulse reappearance 50 



Position II „ „ 45 „ „ 40 



Position III „ „ 130 „ „ 125 



"A „ „ 119 „ „ 109 



B „ 'i£ 65 „ „ 63. 



Position IV 



The subject was in the horizontal position in all cases. 



The low reading of 55-50 mm. of Hg at position I cannot be due to any 

 fault in the transmission of pressure through the bag to the arterial wall 

 Consequently, we assume that the pulse has disappeared at 55-50 mm. 

 of Hg before the blood flow has ceased through the artery. In other words, 

 the phenomenon of arresting the pulse by occlusion of the artery is not 

 brought into play in this observation. 



Two methods suggest themselves by means of which it can be proved 

 that when the pulse ceases to be felt at position I the arterial flow is still 

 maintained, that the pulse has, as it were, been skimmed off the current. 



Keeping the bag of the sphygmometer pressed on position II with a 

 pressure of 180 mm. of Hg, one can strip the blood out of the artery, and, 

 to prevent recurrent flow, fix the artery below, as it clips through the 

 interosseous space. By releasing the pressure at II, the lumen of the empty 

 artery can be felt to fill with blood when the pressure in the bag registers 

 115-120 mm. of Hg. It can be felt standing out as a bulging cord at 90 mm. 

 of Hg, while the pulse returns at 60 mm. of Hg. 



It is possible to place the armlet so as to cover position III and part of 



u 2 



