394 



A MANUAL OF VETERINARY PHYSIOLOGY 



contraction are of two kinds — the galvanic or constant current, 

 and the induced or interrupted current. 



The galvanic current is conveniently supplied by a Daniell's cell, 

 (E, Fig. 113), in which zinc is the positive and copper the negative 



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element. These metals are connected with wires to the poles or 

 electrodes. The electrode attached to the zinc element is not, 

 however, the positive, but the negative, or kathode, pole, and, 

 similarly, the electrode attached to the copper is the positive, or 



