during Muscular Contraction. 193 



We need hardly state that the surfaces of the electrodes should 

 be clean and the contacts perfect. 



With the solution of common salt. Upon the first introduction 

 of the fingers, a slight tremulous motion of the needle occurred. 

 Withdrawing the right-hand fingers and reintroducing them 

 immediately afterwards, and repeating this act a few times, a 

 slight positive effect was produced upon the introduction of the 

 fingers. Withdrawing the left-hand fingers in the same manner, 

 a slight negative effect was at first obtained, but after a short 

 time the effect became indefinite, and ultimately slightly ;wsz7a'e. 

 Keeping the fingers in and contracting the muscles of the arm, 

 the fingers of the contracted arm were positive 4P to 5°, and 

 made to increase. 



The solution in one vessel was now diluted to one-half. Upon 

 the first introduction of the fingers, the strong solution was 

 positive 5°. Keeping the fingers in and waiting until the needle 

 had become motionless, the contracted arm was positive to the 

 other ; if the arm connected with the strong solution was con- 

 tracted, the effect was greater than when the other was con- 

 tracted, the current in the former case rising to 5°, in the latter 

 to 2° or 3°. 



With the acid solution. Upon the first introduction of the 

 fingers, the needle would sometimes go 30° or 40°, but generally 

 speaking it would oscillate first to one side and then to the other. 

 Withdrawing the fingers of one hand and then reintroducing 

 them, this hand was positive to the other. Keeping the fingers 

 quiescent, and contracting the muscles of the arm, the corre- 

 sponding fingers were positive 4°. 



The solution in one vessel was diluted to half the strength of 

 the former ; the strong solution was positive to the other upon 

 the introduction of the fingers. If the difference between the 

 two solutions was not too great (the exact strength being diffi- 

 cult to state), we might determine a slight current to pass in a 

 constant direction, and then make the current arising during 

 muscular contraction overcome this constant current. Strong 

 solutions were found best for this purpose, from their forming, 

 perhaps, a better conducting hquid than the weaker solutions. 



With the alkaline solution. Upon the first introduction of 

 the fingers no definite result, the needle tremulous. Withdraw- 

 ing 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 2° to 4°, the fingers of the contracted 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 



