324 ELECTRO-PHYSIOLOGY CHAP. 



and transverse section. Indeed, there is some justification for 

 the further postulate of electromotive activity in the same sense 

 in each fraction of a primitive fibre. Thus du Bois-Eeymond 

 arrived at the conclusion that each muscle-fibre was composed of 

 minute electromotive particles (" molecules ") suspended in a con- 

 ducting fluid, and he developed on this basis a theory of the 

 electrical phenomena in animal tissues, which long held the field 

 undisputed. It was a necessary corollary of this view to suppose 

 as seemed to be supported by experiment that uninjured, 

 striated muscle with a natural transverse section gave exactly the 

 same electromotive reaction as that furnished with an artificial 

 cross-section. By " natural transverse sections " du Bois-Eey- 

 mond understands the total of the uninjured ends of muscular 

 fibres still normally connected with the tendon. This theory of 

 the electromotive equivalence of artificial and natural cross- 

 sections rests mainly upon the electromotive reaction of the 

 apparently uninjured frog's gastrocnemius, and the complicated 

 structure and general application of this muscle make it advisable 

 to examine more closely into the much-discussed " gastrocnemius 

 current." Leaving out for the moment the fact that the really 

 uninjured muscle gives no electromotive reaction (infra}, it may be 

 assumed that the achilles tendon is, as in the majority of cases 

 where no special precautions are taken, negative towards the 

 remaining surface of the muscle. Owing to the complex struc- 

 ture, the distribution of surface potential will then be far more 

 elaborate than in a muscle cylinder with regular parallel fibres. 

 Eosenthal (2) gives a very comprehensive description of the 

 structure. 



" Two plates of tendon, above and below, are joined by 

 muscle -fibres running obliquely between them, so as to form a 

 semiplumiform muscle. Now let the upper tendon -plate be 

 folded in the middle, like a sheet of paper, and the two halves 

 grown together. There is thus an upper plate of tendon lying 

 inside the muscle, with muscle -fibres starting obliquely from it 

 on either side ; the lower tendon is, however, curved through 

 the folding together of the upper, so that the whole muscle 

 assumes the form of a root, cleft louo-itudinallv : its smooth 



O i/ 



surface (which laces the bone of the shank) consists entirely of 

 muscle-fibres, and exhibits only a fine longitudinal streak as indi- 

 cation of the tendon concealed within, while the bulging dorsal 



