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which is derived from two points of the uncut surface. On laying 

 the thigh upon the cushions which form the electrodes of the galva- 

 nometer, the needle diverges under the current of the relaxed muscle ; 

 on producing contraction by irritating the nerve with a feeble inter- 

 rupted current, the needle immediately travels back and passes to 

 the other side of zero. The fact is undeniable, but, according to the 

 author, the backward movement of the needle does not indicate, as 

 Prof. Matteucci supposes, a reversal of the muscular current during 

 contraction. There is, it is true, no secondary polarity in the galva- 

 nometer to drive the needle back, as in the case where platinum 

 electrodes are used ; but there may be a tendency to oscillate back- 

 wards, and the question is whether the mere movement of oscillation 

 may not be sufficient to account for the phenomena. What must 

 be done, then, is to compare the rate at which the needle moves 

 backward during contraction with the rate at which the needle falls 

 backward in simple oscillation ; and when this is done, the author finds 

 that the needle moves backward more slowly during contraction than it 

 does when it is simply left to oscillate in the same direction. It is found, 

 indeed, that there is no reverse current during contraction, for if 

 there were, the impulse of this current would be added to the impulse 

 of oscillation, and (as is the case where the platinum ends are used) 

 the needle would go backwards more quickly during contraction 

 than it does when left to fall backwards from the same point under 

 the influence of simple oscillation. There is also another way of 

 showing the non-existence of a reverse current during muscular con- 

 traction, namely, by modifying the experiment in the way which 

 Prof. Du Bois Reymond employs to get rid of the secondary polarity 

 of the platinum ends. The only difference between the experiment 

 as modified and the original experiment is this that the wire of one 

 of the electrodes is broken, and the broken ends are connected by 

 being dipped into a small cup of mercury. An arrangement is thus 

 made by which the circuit may be easily broken and closed again. 

 In performing the modified experiment, the degree and direction of 

 the current of the relaxed muscle is first observed. Then the cir- 

 cuit is broken by removing the end of the divided electrode out 

 of the cup of mercury, and the needle is allowed to return to zero. 

 In the next place, the muscle is tetanized, and while in this state, it 

 is included in the circuit of the galvanometer by replacing the end 



