iv ELECTROMOTIVE ACTION IN MUSCLE 449 



The earlier, and contrary results of du Bois-Eeymond 

 are, as Hering showed, to be referred to the fact that he em- 

 ployed two muscles, one of which was entirely, the other at least 

 partially traversed by a tendinous intersection. On leading off 

 from two points of the interpolar tract, there must as a rule be 

 countless anodic and kathodic points between the contacts o 

 the leading-off circuit, more especially when the tendinous wall 

 of partition (running obliquely to the muscle axis, and dividing 

 each of the two muscles so as to form two separate muscles lying 

 one behind the other) falls completely within the two galvano- 

 meter electrodes. In front of the intersection the current 

 leaves by the fibres of one of these separate muscles, to enter 

 again by the fibres of the second. On one side of the inter- 

 section therefore there are countless kathodic, on the other as 

 many anodic, points, and both are the seat of polar changes. 



Here too du Bois-Reymond has recently tried to give another 

 interpretation from the standpoint of the molecular theory, but 

 it is so obviously inadequate that he himself recognised its great 

 difficulties, which are not removed by a whole series of accessory 

 hypotheses. The polarisation effects in the gracilis muscle are 

 derived by this theory tested on a " clay dummy " (consisting 

 of a round clay stamp, hollowed out in the centre, with the 

 patellar tendon of a frog clamped between its two halves) from 

 " an axially directed, antagonistic force, initiated in each super- 

 ficial element of the intersection." Experimental observations, 

 however, did not correspond with the theoretical response of the 

 muscle, and du Bois-Reymond was compelled to adopt the theory 

 of a " false internal polarisation," for which no explanation is 

 given. The parelectronomic tract, or layer, on the other hand, 

 is the seat of " true " polarisation at the ends of fibres. Du Bois- 

 Reymond, however, considered it impossible to refer this to the 

 negative variation, because " no such relation seems to obtain 

 between the mechanical effects of excitation and polarisation, as 

 must exist if polarisation is to be conceived as the after-effect of 

 negative variation, or as the negative variation proper." He 

 therefore takes no account of the fact that such complete parallel- 

 ism exists just as little between the visible effects of the opening 

 excitation and the positive anodic after-current, although there 

 can be no doubt as to the causative connection between them. 

 Du Bois indeed goes so far as to deny the presence of per- 



2 G 



