x ELECTROMOTIVE ACTION IN NERVE 327 



physiological action of current. It is singular that it should 

 date from a time at which the law of polar excitation was still 

 unknown, since the evidence of the latter again turns our 

 thoughts, almost involuntarily, in the same direction. Von 

 Bezold expresses himself directly in this sense at the close of 

 his detailed investigation into the electrical excitation of nerve 

 and muscle. In the fact that " the molecular process of excitation 

 arises with such regularity at and during closure, and on opening 

 the current, at a definite pole, and not in the whole extension of 

 the tract through which the current is passing," he sees evidence 

 that " the excitatory action of the galvanic current is to be sought in 

 the chemical effects produced ~by the current in the moist conductor 

 which it traverses" (I.e. p. 237). He recalls the antagonism of 

 the polar alterations, and Kiihne's remark that a tract of muscle 

 traversed hy current shows coagulation in the region of the anode, 

 and corrosion at the kathode, as well as Jtirgensen's experiments 

 upon the cataphoric action of the current, and concludes from 

 all these data that the excitatory process is nothing more than 

 an effect of electrolysis due to current. " Electrical excitation 

 would, accordingly, be nothing else than a definite form of chemical 

 stimulation the process, like that of the generation of hydrogen, 

 occurring exclusively at the negative pole, during closure of the 

 current" (I.e. p. 328). The arguments adduced (by von Bezold 

 in particular) to show that the process of excitation is dis- 

 charged at the kathode during the entire passage of the current, 

 are obviously quite in line with this theory. 



The greatest advances in the direction indicated came, how- 

 ever, from Hermann's electro-physiological researches, which most 

 of all contributed to bringing forward the chemical side of function 

 in all these vital phenomena, while the resolution with which he 

 attacked du Bois-Eeymond's molecular theory helped to remove 

 one of the greatest hindrances to the fruitful development 

 of general nerve and muscle physics. Hermann's law of the 

 current of action (to the effect that each excited part is negative 

 to parts that are less excited, or unexcited) forms, indeed, with 

 the law of the exclusively polar action of electrotonic currents in 

 excitable tissues, the basis of all modern opinion on the subject, 

 and gives the key to the interpretation of a vast number of 

 experimental data. Hering, again, like Hermann, has steadily 

 maintained that all the processes in excitable living matter are, in 



