ANIMAL KLECTRICITV. LECTURE IV. 8 I 



plication due to the fact that the nerve is not isolated, 

 but embedded. Notice only that there is a contraction 

 at break, which contraction is due to excitation of the 

 nerve just under the anode, and let that signify for you 

 that the anode excites at break, i.e., that the break 

 contraction is anodic. 



These two statements — that the kathode excites 

 at make and the anode at break — will be supple- 

 mented by the double statement that during the 

 passage of a constant current, excitability is increased 

 at the kathode, decreased at the anode — which is easily 

 to be demonstrated. And the clearest and least ob- 

 jectionable way to do this will be by an apparently 

 very clumsy proceeding, viz., by light blows to the 

 nerve, through the medium of the electrode itself, 

 which is made anodic or kathodic at pleasure. Pressing 

 the electrode somewhat carefully upon the nerve, it is 

 regularly tapped by a light mallet, just hard enough to 

 give distinct twitches of the hand and fingers. While 

 the taps and twitches are proceeding regularly, a key 

 is closed, rendering the electrode kathodic, and the 

 twitches are evidently more pronounced, whereas with 

 reversed current and an anodic electrode they are 

 abolished. This double experiment — of which the 

 principal virtues are that it is simple, and that me- 

 chanical, i.e., non-electrical, stimulation of perfectly 

 normal nerve is employed — is good and sufficient 

 evidence of the double statement that excitability is 

 increased under kathodic influence and diminished 



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