536 CIRCULATION OF BLOOD AND LYMPH. 



the case of hearts with a slow rate of beat. The usual explanation 

 of this wave is that it is due to the very sudden distention of the 

 ventricles by the inflowing blood. The rise in intra ventricular 

 pressure thus produced brings the auriculoventricular valves 

 suddenly into a position of closure and causes a momentary posi- 

 tive wave in the auricles and great veins. For the variations in 

 the form of the venous pulse under pathological conditions of the 

 heart, reference must be made to clinical literature.* 



* See Hewlett, "Journal of Medical Research," 17, 1907; "Journal of 

 the Amer. Med. Asspc.," 51, 1908, and Hirschfelder, "Diseases of the 

 Heart and Aorta," Philadelphia, 1910. 



