VARIATIONS IN THE PULSE. 307 



erotic notch, and give the curve known as characteristic of "high 

 tension " pulse, as in Bright's disease. (Fig. 141, II.) On the 

 other hand, when the arterioles are widely dilated (corresponding 

 to the open condition of the tube) a negative wave is reflected, 

 and is subtracted from the force of the pulse-wave so as to exag- 

 gerate the dicrotic notch, and give the tracing characteristic of 

 the "low tension " pulse seen in fever, etc. (Fig. 141, III.) 



The mean rate of the pulse varies in different individuals, 

 seventy-two per minute being a fair average for a middle-aged 

 adult. It varies also with many circumstances, which must be 

 borne in mind in taking the pulse as a clinical guide. 



FIG. 141. 



I. Scheme of Normal Pulse Curve : a, Entrance of ventricular stream 

 into the aorta, the lever is jerked too high to reach * ; a b shows real summit 

 of waves ; 6, point at which stream from ventricle ceases ; c, negative wave 

 caused by (1) sudden cessation of inflow and slight reflux of blood ; d, point 

 of closure of aortic valves ; e, positive wave from valves (dicrotic wave). The 

 time may be measured on abscissa at a 7 V d f . 



II. Scheme of High Tension Pulse Curve : A, curve of radial pulse, which 

 is the resultant of positive reflected wave c, added to the primary curve B. 



III. Scheme of Low Tension Pulse Curve: A, radial pulse curve, which 

 is the resultant of the negative reflectant wave c, subtracted from the primary 

 wave B. (After Grashey.) 



1. Age. At birth it is about 140 per minute, and is, generally 

 speaking, quicker in young than in old people, commonly falling 

 to 60 in aged persons. 



2. Sex. It is more rapid in females than in males. 



3. Position. It is quicker standing than lying, particularly if a 

 patient who has been lying down, stand or sit up, the pulse be- 

 comes more rapid. 



