iv ELECTROMOTIVE ACTION IN MUSCLE 459 



the conclusion that there is here, as it were, a reaction of the 

 living substance towards the preceding excitation. 



The results arrived at in the previous discussion of the visible 

 effects of electrical excitation in cardiac muscle, as also in differ- 

 ent smooth muscular parts (holothurian and echinus muscle), 

 are essentially confirmed and elucidated by these secondary 

 electromotive phenomena. For they establish with certainty the 

 general validity of those conclusions to which (more particularly) 

 the observations on the effects of excitation on cardiac muscle 

 in a state of alternating contraction had pointed. 



The theory of two inhibitory processes antagonistic to the 

 polar processes of excitation, which we found to be inevitable 

 re cardiac muscle in systole, now proves to be the simplest 

 explanation of the consequences of electrical excitation of striated 

 skeletal muscle. This is equally true of the mechanical effects 

 of excitation, and of the electromotive after-effects. The two 

 methods of investigation, whether by testing the changes of 

 form in the excited muscle, or by ascertaining the state of 

 polarisation at the end of excitation, complete themselves 

 reciprocally, so that a satisfactory view of the nature of the 

 changes due to current is first obtained from the combination of 

 both methods. We must especially remark that a direct proof 

 of the existence of an antagonistic process, following or preceding 

 the excitation, as expressed in corresponding changes of form in 

 the muscle, is obviously possible only during pre-existing persist- 

 ent contraction, but may in other cases be concluded very 

 indirectly, e.g. by examination of the alterations of excitability. 

 On the other hand, the investigation of secondary electromotive 

 phenomena gives positive evidence of the existence of polar 

 antagonistic processes in the resting muscle also. 



In conclusion, the positive anodic and negative kathodic 

 after -current on the one hand, the positive kathodic and 

 negative anodic after-current on the other, are due respectively 

 to the antagonistic polar alterations of the muscle-substance, one 

 of which tends to negativity, the other to positivity, of the 

 points of fibres implicated. To the former correspond (as 

 mechanical effects of excitation) the closing and opening con- 

 traction, to the latter (where this is a tonic state of contraction) 

 the closing and opening relaxation. The one, like the other, is 

 conditioned by chemical alterations in the excitable muscle- 



