444 ELECTRO-PHYSIOLOGY CHAP. 



corresponding usually with first a negative and then a positive 

 polarisation. This is due to the fact that from the moment 

 of closure onwards, loth kinds of polarisation are simultaneously 

 present, but increase in different proportions, " negative polarisa- 

 tion increasing more in ratio with the time of closure, while the 

 positive variation is augmented quickly at first and then more 

 slowly." 



Du Bois-Eeymond further concluded from experiments in 

 which the upper and lower half of regular muscles were alter- 

 nately traversed by the current, and tested for polarisation, that 

 " strong positive polarisation is exhibited in the upper half in an 

 ascending, in the lower half in a descending, direction." Dead 

 muscles still exhibit traces of negative internal polarisability 

 which is completely abolished only by boiling ; positive polarisa- 

 tion, on the other hand, is exclusively characteristic of living 

 muscle. Du Bois-Reymond concluded that " it is not electro- 

 motive forces, homodromous with the primary current, which are 

 generated by the positively polarisable tissues, but the carriers 

 of electromotive forces already present (electromotive molecules) 

 which are homodromously adjusted with the primary current." 



How little these results really go to support the molecular 

 theory, however, is strikingly obvious in the later investigations 

 of Hering and Hermann (6869). Hering proves conclusively 

 that there can be no question of internal positive or negative 

 polarisation in a longitudinally traversed muscle in du Bois- 

 Reymond's sense, since the actual seat of the electromotive 

 changes induced by the exciting current lies at those points of 

 the contractile substance by which the current enters or leaves 

 the muscle (the physiological pole), so that the close relation 

 between these phenomena and the polar effects of current is 

 unmistakable. 



If, in the same sense as above, we regard every change in the 

 chemical activity of any part of the muscle-fibre as the sine qua 

 non of the appearance of electromotive action, we shall premise 

 that on sending current through a muscle with parallel fibres, 

 the chemical alteration of the contractile substance recurring 

 presumably at the physiological kathode and anode will initiate 

 differences of potential, which must be discovered when one or 

 other end so altered of the muscle is led off in connection with 

 a point of the unaltered surface of the muscle. The results 



