IX. 



IN a recently published treatise *, E. du Bois-Reymond discusses 

 the so-called secondary electromotive phenomena 2 as observed by 

 him in muscle, nerve, and electromotive tissues, in order to give fresh 

 support to his molecular hypothesis and his theory of electrotonus, 

 against both of which, to my mind, fatal objections have been 

 raised. 



How important the author regards this support is seen in the 

 opening sentences, 'I think it is now time to break the silence 

 which I have hitherto maintained regarding certain experiments 

 on the electromotive phenomena of tissues, with which I have been 

 occupied nearly forty years, and to which I attach great import- 

 ance,' as well as in the repeated expressions according to which all 

 my ideas upon eleetrotonus had now been exploded, so that the 

 elucidation of the subject would have to be begun anew 3 . 



In consideration of the heavy artillery brought against me, it 

 will not be taken amiss if, without waiting for the further communi- 

 cation upon the same subject announced by the author, I go over 

 the facts of the new position. It will then be seen to what extent 

 the expectations and expressions of du Bois-Reymond are justified. 



1. Facts observed by du Bois-Reymond. 



THE facts, in part new, in part previously stated, which du Bois- 

 Reymond adduces, are briefly as follows : 



1 ' Sitzungsberichte der Konigl. Preuss.' Acad. der Wissenschaften, 1883, p. 404. 



2 Du Bois-Reymond describes aa secondary electromotive such electrical pheno- 

 mena as are produced by leading a current into an animal tissue, but are not 

 detected in the tract through which the current has passed until after this is broken. 

 He places the electromotive phenomena of animal tissues under three categories : 

 (i) Currents inherent to the tissue at rest or in action ; (2) Extrapolar effects of led- 

 through currents during tiheir passage ; (3) Intrapolar effects of the same, i.e. the 

 secondary electromotive phenomena. In this enumeration are omitted the extra- 

 polar effects following the break of a current, the laws of which I first stated with 

 regard to nerve, as du Bois-Keymond himself has mentioned. Concerning these 

 phenomena in nerve and muscle see later. 



3 See No. VI of this Series, Sect. 15. 



