THE CIRCULATION. 



265 



Fig. 82- Innervation of Heart. (PowEix.) 



VMC, Vasomotor center. A of V, Annulus of Vieussens. GSt, Ganglion stel- 

 latum (First thoracic). 2dTG, Second thoracic ganglion. SdTG, Third thoracic 

 ganglion. Vagus is denoted by continuous lines arrows toward heart. Depressor 

 nerve is represented by dotted points arrows from heart. In man the cardiac accel- 

 erator branches travel to the heart from the annulus of Vieussens and cervical 

 sympathetic. 



If the beats are more than this, say 200 per minute, there must be a 

 temporary dilatation of the heart. 



When the irritated vagus arrests the heart the first succeeding 

 contractions are stronger or more numerous than previously, and the 

 work of the heart is greater. An excess of carbonic acid in the blood 



