124 THE VASCULAR SYSTEM 



blood pressure, e.g. 250 mm. Hg, obtained, should be endured by 

 the circulatory mechanism. As to the question of brittle arteries, 

 in order that the obliteration method should fail, the artery must 

 be rigid in the whole of its course enclosed by the sphygmometer. 

 Rigid atheromatous patches with soft parts between would not 

 disturb the readings. On inquiry among clinicians and patho- 

 logists the writer has not obtained from them evidence of the 

 existence during life of such rigid contracted arteries as W. Russell 

 describes. The post-mortem carotid of the ox, contracted maximally 

 by mechanical irritation, feels as if it would require some pressure 

 to obliterate it. What pressure is required the writer has not suc- 

 ceeded in ascertaining owing to the difficulty of putting the whole 

 length of the artery which is enclosed in the gauge in a state of 

 such contraction. G. Oliver finds in states of sclerosis considerable 

 differences between the armlet readings and those obtained with his 

 hsemodynamometer, a metal spring gauge used with a small fluid 

 pad on the radial artery, and believes that the maximal pulsation 

 index thus obtained is the safer guide because it necessitates, not 

 the obliteration of the artery, but only the balancing of the pressure 

 wave. Now the maximal pulsation method shows two maxima, 

 one corresponding it is said to the diastolic pressure and the 

 other to the pressure which obliterates the artery, i.e. the systolic 

 pressure. The second maximum is produced by the pulse wave 

 striking against the upper edge of the pad or bag, and diminishes 

 when, as the pressure is lowered, the systolic wave just slips through 

 the artery (Erlanger). 



Oliver prefers this index to that of pulse obliteration. He 

 gives readings taken from the arm and forearm, on the two arms 

 of the aged, by the obliteration method, and adduces the variation 

 of these as evidence that the method of obliteration is liable to 

 error. Thus 



Woman Recumbent, 90 Years old. 



