H4 A MANUAL OF PHYSIOLOGY 



by a spring manometer, and with records of the external pulse 

 obtained by a sphygmograph. There is a primary increase of 

 velocity corresponding with the ventricular systole, and a 



Plet hys m o & T ct in 



FIG. 42. FIG. 43. 



FIG. 42. The highest of the three curves is a plethysmographic record taken 

 from the hand ; the second curve is a sphygmogram taken simultaneously from 

 the corresponding radial artery ; the lowest (interrupted) curve is the curve of 

 velocity deduced from a comparison of the first two (Pick). 



FIG. 43. Simultaneous plethysmographic and sphygmographic tracings. 



secondary increase corresponding with the dicrotic wave (Fig. 45). 



Like all the other pulsatory phenomena, the velocity-pulse disap- 

 pears in the capillaries, 

 and is only present 

 under exceptional cir- 

 cumstances in the veins. 

 Fick, from a com- 

 parison of sphygmo- 

 graphic and plethys- 

 mographic tracings 

 (p. 117), taken simul- 

 taneously from the 

 radial artery and the 

 hand, has demon- 

 strated that in man 

 the velocity-pulse ex- 

 hibits the same general 

 characters as in 



animals (Figs. 42 and 

 FIG. 44. UYBULSKI s ARRANGEMENT FOR RE- v \ A if v, 



CORDING VARIATIONS IN THE VELOCITY OF 43)' And V. Kries has 



THE BLOOD. 



A, tube connected with central, B with peri- 

 pheral end of divided bloodvessel. The blood 

 stands higher in the tube C than in D. A beam of 

 light passing through the meniscus in both tubes is 

 focussed by the lens L on the travelling photo- 

 graphic plate E. The velocity at any moment is 

 deduced from the height of the meniscus in the two 

 tubes C and D. 



confirmed Fick's con- 

 clusions by actual re- 

 cords of the velocity- 

 pulse obtained by 

 means of an arrange- 

 ment called a gas 

 tachograph (Fig. 46). 



