PHENOMENA OF MUSCLE. 231 



originating in the neighbourhood of the anode an action-current 

 indeed which behaves in a manner essentially different from the 

 action-currents consequent on instantaneous stimulations. Never- 

 theless, I will provisionally speak of this break action-current as a 

 polarisation-current. 



The facts contained in the preceding communication gave suf- 

 ficient evidence that the internal polarisation adopted by du Bois- 

 Reymond was not the actual cause of the secondary electromotive 

 phenomena observed by him ; yet I feel it my duty to give a 

 still more thorough refutation of his interpretation of those 

 phenomena. 



I. 



In his researches, du Bois-Reymond made use of two muscles at 

 the same time, i.e. the rectus internus major (Ecker), which Cuvier 

 calls adductor magnus and du Bois-Reymond gracilis, and the semi- 

 membranosus (Cuvier, Ecker, du Bois-Reymond). 



The first tapers to a thin tendon at both ends, and is a tolerably 

 symmetrical muscle. A tendinous intersection, (inscriptio tendinea,) 

 however, runs obliquely through the middle third, which com- 

 pletely divides the muscle into an upper and a lower portion. 



The greater portion of the semimembranosus is likewise traversed 

 by an oblique tendinous intersection, hence it only partly consists 

 of long fibres. Besides this it is very unsymmetrical, rising by a 

 broad tendon from the pelvis, and tapering from above downwards, 

 at first gradually, afterwards rather rapidly, to end in a thin tendon. 

 The intersections of both muscles were fully described and depicted 

 by du Bois-Reymond in a former research 1 . He noticed moreover 

 ' that the semimembranosus in a portion of its length from below 

 upwards receives fresh accessions of fibres, which arise from both 

 sides of a strip of tendon projecting at its outer side.' 



Both muscles were so prepared for the purpose of experiments on 

 polarisation, as to remain attached to each other, and in addition to 

 portions of the pelvis and tibia. By means of these bones they 

 were extended on a 'muscle-frame' or stretcher and arranged as 

 one single thick muscle. 



' Close to the ivory plates of the stretcher, the wedge-shaped pads 



On negative variation of the muscle-current; Gesammelte Abh. vol. ii. p. 575. 



