Rate of Propagation of Venous Pulse. 



209 



If now one indicates with (a) the distance in centi- 

 metres between the vertical lines marking the beginning 

 of a given wave in the two tracings, with (s) the rate at 

 which the recording surface travels in centimeters, with 

 (^/y~0 t^^6 length of vein being studied, and with (y) the 

 rate of propagation of the pulse in that length of vein, then 



v = s ^^-^ ' 



a 



As regards the presence of a pulse in the veins of the 



animals experimented on, it may be said that one could 



always be observed and recorded in the central end of the 



jugular. In most cases it could also be recorded from the 



distal end of the jugular and from the femoral ; but the- 



waves were sometimes not sharp enough for satisfactory 



marking. The estimations reported below were taken 



1^.3 



Fig. 4. — Pressure tracing from central (below) and peripheral end 



(above) of external jugular vein. Time in seconds. From a dog. 



from cases where the markings were considered reliable 

 enough to make the errors very slight. It is a noteworthy 

 fact, that the best tracings were frequently obtained from 

 the smallest and weakest dogs. Similar observations have 

 been made by Gottwald (1) on dogs, and G-erhardt (2) on 

 human subjects. Gerhardt claims to have observed the 

 venous pulse most frequently in weak and anaimic girls. 

 Although a discussion of the form of the venous pulse 

 does not properly find a place in this paper, it is necessary 

 to allude to it briefly in order to have names for the vari- 

 ous waves whose rate of propagation was studied. Fol- 

 lowing Fredericq (4), Gerhardt (2) and others, I distinguish, 

 as may be seen in Fig. 4, a presystolic wave, 0, a systolic 



