CH. XXIL] 



VENOUS BLOOD-PKESSUKE 



275 



Fig. 240 shows a more complete view of the manometer, and 

 fig. 241 is a diagram of the arrangement by means of which it is 

 made into a kymograph. 



Fig. 242 shows a typical normal arterial blood-pressure tracing on 

 a larger scale. 



KIG. 242. Normal tracing, somewhat magnified, of arterial pressure in the rabbit obtained with the 

 mercurial kymograph. The smaller undulations correspond with the heart-beats, the larger curves 

 with the respiratory movements. The abscissa or base-line, which on this scale would be several 

 inches below the tracing, is not shown. (Burdon-Sanderson.) 



Iii taking a tracing of venous Hood-pressure, the pressure is so low 

 and corresponds to so few millimetres of mercury, that a saline 

 solution is usually employed instead of mercury. If the vein which 



FIG. 243. A form uf Kirk's Spring Kymograph, a, Tube to be connected with artery ; c, hollow spring, 

 the movement of which moves b, the writing lever ; e, screw to regulate height of b ; d, outside 

 protective spring ; g, screw to lix on the upright of the support. 



is investigated is near the heart, a venous pulse is exhibited on the 

 tracing, with small waves as before corresponding to heart-beats, and 



