CHAP. X. §. I. DURING MUSCULAR CONTRACTION. 117 



tremulous. Withdrawing the fingers and reintroducing 

 them, the effects varied, but, generally speaking, the 

 reintroduction of the fingers produced a negative 

 result. The effect due from muscular contraction 

 was definite from 3° to 4°, the fingers of the con- 

 tracted arm being positive. 



The solution in one vessel was diluted to half the 

 strength of the other. Upon the introduction of the 

 fingers, the diluted solution was positive to the 

 stronger. I was enabled in this instance, as with 

 the acid solution, to obtain a solution of such 

 strength as to give a constant current in a certain 

 direction, and then make the current due from 

 muscular contraction overpower this current. As 

 this fact is one of some importance, it will be 

 necessary to state the mode of ascertaining this 

 constant current. If we find, either upon the 

 introduction of the fingers of both hands at the same 

 time, or upon the introduction of the fingers of one 

 hand, that a current existed in one direction to the 

 amount of about 2°, the current occurring during 

 muscular contraction, if it coincided with this con- 

 stant current, would cause the needle to advance to 

 4° or 5° or more ; but if it has to overcome this con- 

 stant current, the needle would only move 2° or 3°. 

 I need scarcely add, that the needle of the galva- 

 nometer should continue to indicate this current 

 whilst the fingers remain in the solution, which may 

 be indicated by the needle receding to its normal 

 position upon the withdrawal of the fingers. A 



