PRESENT STATE OF 0^vGA^'lC ELECTRICITY. 331 



experiment may "be made. Tlie forefinger of each hand being 

 dipped into the saline solutions along M'ith the electrodes of 

 the galvanometer, no deflection occurs. But if all the muscles 

 of one arm he strongly and continuously contracted, a current 

 is indicated as passing from the fmger to the shoulder in the 

 contracted ann, and in the opposite direction in the relaxed 

 one. It is evident that this current is the residt of the dimi- 

 nution of the ordinary general muscular cuiTcnt in the con- 

 tracted arm, and the suhstitution for it of the closed circuit 

 of the ordinary current of the opposite arm.* 



The Electric Properties of Nerve. — Tlie resemblance between 

 many actions of the ner\'ous system and certain electric phe- 

 nomena has frequently impressed physiologists ; hut investi- 

 gations of this subject have been so generally mixed up with 

 that of the electricity of muscle, as to lead to no precise 

 result. Matteucci had failed in obtaining any indication of 

 electric currents in nerves ; but, nevertheless, the singular 

 parallelism between the two powers could not be overlooked ; 

 and Faraday has pointed out the importance of such considera- 

 tions in his statements regarding electro-nerv'ous action and 

 reaction. ]\Iore recently, Du Bois Eeymond has admitted 

 that electricity and the nervous force are at least equivalents. 

 He was the first to derive electric currents from the nerves, 

 and has procured many most remarkable results from his 

 researches on the subject. 



The Electric Condition of a Nerve in the Intervals of Func- 

 tional Activity. — By employing a very delicate galvanometer, 

 Du Bois Eeymond has detected the electric current in nerve, 

 and has determined its laws. They are similar to those of 

 the muscular current, having the same relation to the longi- 

 tudinal and transverse sections ; except that as the nerve 

 presents no natural transverse section, the relative conditions 



• The general muscular cuirent and the frog-current are treated of in the 

 first chapter of section iii. of the Untersuchungm. 



