166 



THE PULSE. 



[BOOK L 



by two, three, or several smaller elevations and depressions: 

 secondary waves are imposed upon the fundamental wave. In the 

 sphygmographic tracing from the carotid and radial reproduced in 

 Figs. 28 and 29 and in many of the other tracings given, these 

 secondary elevations are marked as B, C, D. When one such 



FIG. 29. PULSE-CURVE FROM RADIAL OP MAN. 



Taken with extra vascular pressure of 70 mm. mercury. The vertical curved line 

 L, gives the tracing which the recording lever made when the blackened paper was 

 motionless. The horizontal line forms the abscissa of the tracing. The curved 

 interrupted lines shew the distance from one another in time of the chief phases of 

 the pulse wave, x = commencement and A close of expansion of artery, p, predi- 

 crotic notch, d, dicrotic notch. C, dicrotic crest. D, post-dicrotic crest. /, the 

 post-dicrotic notch. 



secondary elevation only is conspicuous, so that the pulse-curve 

 presents two notable crests only, the primary crest and the second- 

 ary one, the pulse is said to be "dicrotic"; when two secondary 

 crests are prominent, the pulse is often called "tricrotic," where 



FIG. 30. ANACROTIC PULSE-TRACING FROM THE CAROTID OF RABBIT. 



several "polycrotic." As a general rule, the secondary elevations 

 appear only on the descending limb of the whole wave as in most 

 of the curves given, and the curve is then spoken of as "katacrotic." 

 Sometimes, however, the first elevation or crest is not the highest but 



