THE CIRCULATION OF THE BLOOD 321 



Seat of Action of the Vagus Impulses. In the foregoing experiment of 

 which Fig. 147 is a graphic record, stimulation of the left vagus with a fairly 

 strong current was followed by a diminution in both the rate and force of the 

 contraction of both auricles and ventricles, though the effect was most 

 marked in the auricles. From this and similar facts it has come to be the 

 general belief that the inhibitor nerve impulses exert their influence mainly, 

 if not exclusively, on the auricle, and especially on the sino-auricular node, 



FIG. I47.-RESULT OF THE STIMULATION OF THE PERIPHERAL END OF THE 



DIVIDED LEFT VAGUS IN THE RABBIT. (Brodte.) 



and that the cessation of ventricular action is a secondary effect due to the 

 non-arrival across the conducting apparatus of the normal excitation process 



s 



the muscle bundle of His, there is for a time a complete cessation of ven 



