iv ELECTROMOTIVE ACTION IN MUSCLE 359 



of the demarcation current can be observed, even after hours of 

 exposure to ether vapour, which is the more remarkable when it 

 is considered that all the influences which depress excitability 

 have also a general diminutional effect upon the muscle cur- 

 rent. If then, during ether narcosis, a muscle of which the 

 excitability seems to be entirely abolished has no less pro- 

 nounced an electromotive reaction than under normal conditions, 

 the presumption is that the changes in chemical activity of the 

 muscle-substance, which must always be reckoned with in the 

 proximity of a cut surface, persist during the ether narcosis to 

 the same degree as under normal conditions. Another fact of 

 the same significance is that local treatment with salts of K in 

 correspondingly dilute solutions also renders the ether muscle 

 negative at the point of contact. Further, remembering the 

 persistence of the normal physical properties of the narcotised 

 muscle at a time when, even with the strongest excitation, there 

 is no trace of visible change of form, it does not appear so 

 surprising that a muscle, even in the deepest narcosis, should still 

 be capable of electromotive response, although some of its 

 normal vital properties may be fundamentally affected or entirely 

 abolished. For if it is admitted that the " current of rest " owes 

 its origin to a partial " alteration " in the substance, it would 

 follow that it may be expected in all those cases in which the 

 preparations concerned have not been fundamentally disturbed in 

 their normal, chemical composition ; and this both in respect of 

 ether, and of turgescence of the muscle from water. Later on 

 we shall have to discuss other facts which indicate that con- 

 ductivity and contractility of the muscle are primarily abolished 

 by narcosis, while local excitability persists in the sense that 

 certain chemical changes still occur under the influence of chemical 

 stimuli, which, inter alia, go hand in hand with negativity of 

 the points in question. 



II. THE CUKREXT OF ACTION 



A complete account of the earlier theories of electrical 

 activity in muscular contraction would here be out of place 

 since, like the history of the " current of rest ' in muscle, the 

 subject has been thoroughly reviewed by du Bois-Eeymond, 

 in Part II. of the " Unter.suchungen." It is enough to recall 



