LIVING MUSCLE ALONE ELECTRICALLY ACTIVE. 207 



Further, it is to be observed that the electric activity 

 of muscles is connected with their physiological power 

 of accomplishing work. When muscles die, the electric 

 phenomena also become weaker, and finally cease en- 

 tirely when death-stiffness intervenes. Muscles which 

 can no longer be induced to contract even by very 

 strong irritants may indeed still show traces of electric 

 action ; but this power soon disappears. Nor does the 

 electric activity, when it has once disappeared from a 

 rigid and dead muscle, ever, under any circumstances, 

 return. 



Although it may be assumed as proved that the 

 electric activity of muscle is connected with the living 

 condition of the muscular tissue, it must not, however, 

 be inferred from this that this activity is necessarily 

 always present during life. It is conceivable that the 

 preparation necessary for the study of electric action 

 (the exposure of the muscle, its connection with the 

 arch, &c.) might produce changes in the living muscle 

 which are themselves the cause of electric activity. 

 To satisfy this doubt it would be necessary to show the 

 previous existence of electric activity, wherever it is 

 possible, in uninjured men and animals. The great 

 difficulty which lies in the way of such proof has already 

 been mentioned. The more complex is the arrange- 

 ment of the fibres and the position of the separate 

 muscles present in any part of the body, the harder is it 

 to say, a priori, how the separate currents of the various 

 muscles combine. It must also be added, that the skin, 

 through which the electric action is necessarily observed, 

 is in itself somewhat electrically active, 1 and that, in 

 other ways also, it increases the difficulty of proving the 

 1 Theso skin-currents will be again mentioned. 



