270 



PHYSIOLOGY 



CHAP. 



arteriosus ; not by the reflux of a certain amount of blood from 

 artery to ventricle, to produce closure of the valves, as is arbitrarily 

 assumed by Edgren. 



The points g, h, i, which are distinguishable on the long 

 descending shoulder of the cardiographic curve, of course find no 

 analogue in the sphygmogram, because after closure of the senii- 



Fio. 110. Comparison of synchronous sphyginograms of carotid (.s'c) and of radial () (Edgren.) 



lunar valves changes of pressure within the ventricle can no longer 

 be transmitted to the arteries. Here we will only say that the 

 point g, which marks the lowest depression of the cardiographic 

 curve, very probably corresponds with the moment at which the 

 negative pressure in the ventricle exerts the maximum of aspira- 



FIG. 1 11. Synchronous sphyginograms of carotid (.Sc) and femoral (Sf). (Edgren.) 



tion ; that the point h marks the moment at which active diastole 

 ceases, and passive diastole or the true rest of the heart begins; 

 and that finally the point i (which is usually, but not constantly, 

 visible in cardiographic tracings) points to the moment at which 

 presystole commences, causing a certain degree of passive dilatation 

 of the ventricle, as perceived in a gentle rise of the cardiograph 

 button. 



When the rate at which the cylinder rotates is known, and the 



