iv ELECTROMOTIVE ACTIOX IX MUSCLE 349 



tion that the internal current can by no means be neutralised by 

 compensation of the led- off portion of the current. " A muscle 

 with a deriving circuit, of which the current is compensated, 

 behaves as though the circuit were non-existent, and the cur- 

 rents completed themselves in the substance of the muscle." 

 Du Bois-Reymond's comprehensive physical theory of the cuf^ 

 rent in muscle (and nerve) starts from the fact that every 

 particle of muscle that it is possible to examine, exhibits 

 the same normal differences in potential between longitudinal 

 and transverse section. Thus nothing prevents us from pictur- 

 ing the whole muscle and each single fibre as consisting of 

 many little particles or molecules, every one of which has 

 the same electromotive action as the entire muscle cylinder. 

 These may either be conceived as spheres with two negative 

 polar zones and a positive equator (peripolar molecules), or, 

 as du Bois-Reymond assumed later in view of certain facts 

 to be discussed below, as in each peripolar electromotive 

 molecule consisting of two dipolar portions, of which the 

 positive halves are convergent (Fig. 110, b). Accordingly, each 

 artificial cross-section would fall between two positive, never 

 between two negative, planes. For the rest it is quite imma- 

 terial what aspect we give to the individual molecules, they may 

 as well be imagined discs as spheres. The regular arrangement of 

 them, according to the accompanying diagram (Fig. 110), is the 

 sole essential. If now the whole cylindrical, or prismatic, aggre- 

 gate of these same electromotive molecules is conceived as 

 surrounded by a thin sheath of some indifferent conductor (peri- 

 mysiuin, sarcolenima, dead layer at the cross-section), the distribu- 

 tion of potential at the surface will, as has been shown, correspond 

 throughout with the real experimental conditions. With the aid of 

 this hypothesis it is possible indeed to give a simple explanation 

 of all phenomena of the " current of rest " in the muscle, more 

 particularly the fact of the homodromous activity of each least 

 particle of muscle, as well as the so-called " Neigungetrom " in 

 oblique sections. The interpretation of parelectronomy, however, 

 presents difficulties which, on the pre- existence theory, can 

 only be explained by the further assumption as above, that 

 a specific compensating layer is situated at the natural trans- 

 verse section, figured by du Bois-Reymond as consisting 

 of " parelectronomic molecules," whose positive surfaces turn 



