EFFECT OF pll OX i'ARDIOOR.lM 389 



by changing to a more alkaline [K-rlnsino- Huid. Tliis gives us 

 gromid for a plausible explanation of the eJTeet of the \ agus and 

 of the sympathetic nerves on the rate of conduction in the heart. 

 Some evidence has been t)roduced to show that acid ions are 

 liberated in heart muscle when the peripheral end of the cut 

 vagus is stimulated. The inhibitory power of the vagus is increased 

 also on the addition to the perfusion fluid of certain salts of 

 calcium w'hich are known to dissociate wdth the liberation of acid 

 ions (see Blood-clotting). 



Further Reading 



Lewis. " The Mechanism and Graphic Registration of the Heart Beat." 

 Sliaw k Son. 



