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COMPARATIVE ELECTRO-PHYSIOLOGY 



intensely painful. This is because the kathode, at make and 

 during its continuation, induces an enhancement of the excit- 

 ability of the wound-spot. On the cessation of the current, 

 the painful sensation disappears, and the normal smarting is 

 restored. The wound-spot was next made anode, with 



FIG. 359. Effect of Anode and Kathode on Responsive Sensation 

 in Human Hand 



By means of reversing key, R, E in connection with the wound-spot may be 

 made anode, and E' kathode, and vice versa. By alternately pressing 

 the keys, K' and K, feeble or moderately strong E. M. F. may be em- 

 ployed. 



the same E.M.F. as before. The sensation now experienced 

 was one of soothing, the sense of smarting irritation having 

 disappeared. On the stoppage of this current the original 

 irritation was again restored. 



In these experiments we have typical instances of the 

 kathode inducing increase of excitability, and the anode 



