86 OF VITAL MOTION. 



in this process, nor are they necessary to connect one 

 limb with another, for it is found that a metal con- 

 ductor, or pieces of moist paper, will answer this pur- 

 pose quite as well, if not better ; and in this way we 

 may be more fully satisfied that the influence which is 

 generated is electrical in its character. 



In this experiment contraction is induced in the 

 limbs which form the pile, and in them we might in- 

 vestigate the operation of the electric agent. It is 

 better, however, to prepare an additional limb in the 

 same way as the others, and to induce action by 

 bringing it within the circuit. In this case also it is 

 of no moment whether the nerve be left to serve as a 

 conductor, or whether we use metal or moist paper 

 for the purpose. 



On considering the contractions in this limb when 

 it is connected with the pile, they are found to take 

 place at different times, according to the direction of 

 the current. At first there is contraction both on 

 making and breaking the circuit. If the current pass 

 from the thigh towards the foot, there is a powerful 

 contraction on completing the circuit, and a far 

 slighter one on breaking it ; but if the current pass in 

 a contrary direction, namely, from the foot to the 

 thigh, there is a slight contraction on completing the 

 circuit, and a powerful one on breaking it. There is 

 a change, however, if we continue to transmit the 

 electric influence, and eventually the slighter contrac- 



