VII. 



IN my twelfth communication 1 I mentioned du Bois-Reymond's 

 treatise on ' Secondary Electromotive Phenomena in Muscle, Nerve, 

 and in Electrical Organs/ in which he. arrives at deductions directly 

 contradicted by facts which I have established. Du Bois-Reymond 

 concludes from his researches that when an electrical current flows 

 through a muscle, it polarises the whole of the region through 

 which it flows. If this is so, every part of the intrapolar region 

 lying between the galvanometer electrodes should, on breaking 

 the circuit, give an after- or polarisation-current, which, according 

 to the density and duration of the primary current, now opposes, 

 now reinforces it. Equal lengths of the intrapolar region should 

 give equal polarisation-currents, provided the sectional area be the 

 same throughout, so that it would be of no importance from what 

 portion of the intrapolar region the polarisation-current was led off, 

 so long as the length of that portion remained the same. 



Provided the resistance in the galvanometer-circuit is sufficient, 

 the current of polarisation should be correspondingly stronger if the 

 leading off electrodes include a longer tract than if they include a 

 shorter tract, on account of the greater number of electromotive 

 parts between the galvanometer electrodes, and therefore strongest 

 when the whole intrapolar tract is interposed. In this respect the 

 positive or negative polarisation-currents would be quite analogous 

 to the negative polarisation-currents of a charcoal cylinder steeped 

 in weak sulphuric acid, on which account, moreover, du Bois-Rey- 

 mond assumes an ' internal polarisation ' for the whole of the intra- 

 polar tract. 



1 tiber Veranderungen des elektromotorischen Verhalten der Muskeln im Folge 

 elektrischer Eeizung. Sitzungsberichte, vol. Ixxxvii. p. 415. 



