88 POLAEIZED CONDITION OF THK CHAP. VHI. 



than with organic substances ; the essential condition 

 in all these experiments being, that the current 

 should traverse the nerve, the effect — the muscular 

 contraction — remaining the same, whether the cur- 

 rent had its origin in the animal body, or from 

 arrangements formed external to the body, and in- 

 dependent of it. Volta's experiments appear to 

 have been adapted for the purpose of ascertaining 

 the effect of current electricity upon the animal body; 

 Galvani's, for the purpose of ascertaining the origin 

 of the effects that were observed to occur in the 

 animal ; and whatever views he might have enter- 

 tained in regard to the nerve force being identical 

 with ordinary electricity, all subsequent experiments 

 only tend to shew the great difference that exists 

 between these two agents, — the action of current 

 electricity, and that of nerve force. In saying this, 

 however, I am very far from denying that nerve Jorce 

 is a polar force, and consequently it must bear some 

 relation or connection with the other jtolar forces ; 

 nerve force being, as Db. Todd has pointed out, a 

 higher form of polar force, and perhaps the highest 

 form that we are acquainted with; and being such, 

 we may reasonably suppose that its chief and perhaps 

 peculiar polar characteristics can become manifested 

 in the animal body alone. In another chapter this 

 question will again come under consideration. 



The following conclusions in regard to the origin 

 of the so-called muscular and nerve currents may 

 be deduced from the foregoing experiments : 



