146 NEEVE FOECE CHAP, XI. 



In De la Eivb's valuable Treatise on Electricity^, 

 and to which I must refer, as containing perhaps the 

 most recent views in regard to this question, wiU be 

 found the following important remarks : "We know," 

 says De la Eive, " that the nerve possesses of itself 

 a certain electrical state, which we have succeeded 

 in determining ; we know, moreover, that this electric 

 state is modified by every excitation exercised upon 



the nerve Now if by any cause whatever the 



electric state of the nerve is modified, equilibrium 

 is destroyed ; and from this there results a con- 

 traction of the muscle, or a sensation. Before 

 studying the consequences of the modification, we 

 may remark, that it consists in the fact that the 

 organic molecules of which the nerve is formed are 

 not polarised transversely from within outwards, but 

 longitudinally from one extremity to the other, as is 

 every conducting body traversed by an electric cur- 

 rent. When the modification arises from the imme- 

 diate action of the nervous centre, it appears that 

 the polarisation is brought about always in such 

 a manner, that the negative poles of the molecules 

 are turned on the side of this centre, and the positive 

 on the side of the muscle, as would result from the 

 action of an electric current that might be travelling 

 in the direction of the nervous ramifications. This it 

 is that explains why an electric current which travels 

 in this direction favours the contraction much more 



s A Treatise on Electricity, by Aug. Db la Ette. Translated 

 by C. V. Walkee, F.K.S. vol. iii. p. S6. 



