HERMANN VON HELMHOLTZ 



there are formed an infinite number of currents, 

 which travel through the water from the zinc to the 

 copper, and a portion of these may be conveyed by 

 conductors applied to the zinc and to the copper. 

 If, then, a galvanometer be interposed in the circuit, it 

 will be found that the zinc, forming the centre of the 

 cylinder, is positive, and that the copper, forming the 

 sides, is negative, a result comparable to that obtained 

 from a muscle. Du Bois Reymond therefore sug- 

 gested that each muscular fibre is composed of an 

 infinite number of small electro-motive elements, 

 analogous to the cylinder composed of zinc and 

 copper above described. Each little element would 

 have a positive equatorial zone and two negative polar 

 zones, and we may conceive it to be plunged into an 

 intermediate conducting material. He did not mean 

 that these electromotive molecules, or 'carriers of 

 electromotive force,' existed in any histological sense ; 

 they were to be regarded as nothing more than 

 ' the foci of chemical change,' and they were analo- 

 gous to the molecules entering into the conception 

 of the physicist when he discusses electrolysis. 



Du Bois Reymond, in his earlier experiments, 

 thought he obtained a current from an uninjured 

 muscle, that is, from one whose longitudinal and 

 transverse sections were natural and not artificially 

 produced. Later, however, he discovered that if 

 special precautions had been taken not in the slightest 

 degree to injure the muscle, no current was obtained 

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