316 ELECTRO-PHYSIOLOGY CHAP. 



manifestations, it still seems advisable, in view of the previous 

 data, which are based upon a great number of single observations, 

 to attempt to reach certain general standpoints whence a 

 survey of the whole department shall become possible. In the 

 present state of our knowledge it is obvious that this can only be 

 the most general orientation, and we may perhaps say with justice 

 that here, as in other departments of physiology, the final explana- 

 tion is more remote than seemed probable at no very distant 

 period. Du Bois-Eeymond's brilliant discoveries roused a hope, 

 amounting even to conviction in many minds, that the molecular 

 theory so acutely conceived and fraught with such weighty 

 consequences pointed to a real physical comprehension of all 

 phenomena of nerve and muscle activity, although it was clear 

 from the beginning that chemical processes played a no less 

 important part. So strongly, however, had the first view obtained 

 the ascendant, in consequence of the overpowering effect of the 

 data arrived at in experimental physiology by purely physical 

 methods, that there was no hesitation in finding a parallel between 

 muscle and nerve, and dead, inorganic bodies. As against this 

 there has of late been notable progress, most workers now insist- 

 ing on the chemiml aspects of vital function, or at least regarding 

 these as equal with the physical processes. Du Bois-Eeymond, 

 indeed, subsequently defined the electromotive molecules, which 

 he regarded as the constituents of nerve and muscle, as a definitely 

 orientated crowd, with pronounced chemical activity, and Bern- 

 stein, to whom we shall return, took the same view. Neverthe- 

 less, in judging of the significance of this hypothetical molecular 

 structure to vital processes, and more particularly to electromotive 

 changes in the activity of nerve and muscle, stress was laid, not 

 on the concomitant alterations of intra-molecular constitution, but 

 on the physical change of place of each molecule. Du. Bois-Eey- 

 mond himself never attempted to apply his theory to the explana- 

 tion of excitation per se, or its propagation from the seat of direct 

 stimulation. He was contented to derive the correlative galvanic 

 manifestations from it, and expressly warns us against considering 

 the " pile-like " polarisation of the nerve, by which he accounts for 

 electrotonus, to be identical with "the process which conditions 

 movement and sensation" (23, p. 385). Notwithstanding this, 

 there is no lack of conjectures which in this respect far outstrip 

 those of the founder of the molecular theory ; and it is interesting 



