THE ELECTRICAL CONDITIONS OF MUSCLE AND NERVE 61 



Demarcation and action currents of nerve. These are examined and measured 

 in exactly the same way as those of muscle. 



Action current of frog-heart. Non-polarisable electrodes are connected with 

 a beating frog-heart, which may either be removed from the body and laid with 

 the base upon one electrode and the apex on the other, or left in situ and the 

 electrodes connected with apex and base by thick threads wetted with salt 

 solution. The electrodes are joined by wires to any of the above instruments. 

 Each contraction of the heart is accompanied by movements of the respective 

 indicators (mercury column, quartz thread, or magnetic needle), the direction 

 of which may be recorded and the alterations in electrical potential of base and 

 apex deduced therefrom. 



