iv ELECTROMOTIVE ACTION IN MUSCLE 451 



bility, although on the other hand the changes in the two 

 functions do not always keep pace, and the one faculty may be 

 already abolished while the other is still in existence. We need 

 only in this connection refer to the fact that in the process of 

 dying, the manifestations of contraction which appear with 

 mechanical or electrical excitation become more and more COIF 

 fined to the seat of direct stimulation, where they are still 

 energetic when conductivity has been entirely arrested ("idio- 

 muscular contraction "). This is generally explained on the 

 assumption that the conductivity of the muscle disappears, with 

 diminishing excitability, before its direct capacity for response. 

 The same thing may be observed in the course of ether narcosis 

 also, since electrical excitation in the region of the kathode still 

 produces a plain contraction ; although on exciting one end and 

 leading off from the other no trace remains of any negative 

 variation of the demarcation current, i.e. conductivity is almost 

 entirely abolished. In view of these facts it is natural to ask 

 whether the continuation of polarisation effects might not be 

 referred to exclusive localising of both opening and closing 

 excitation to the extreme ends of the muscle-fibres, the shorten- 

 ing of which might easily escape undetected. No such effect, 

 however, is indicated by microscopic observation of the muscle 

 traversed by current, and it may be assumed that with 

 sufficiently prolonged etherisation all perceptible trace of local 

 contraction disappears (in excitation with the electrical current), 

 although the polarisation effects in question may be observed in 

 full vigour before as well as after. We may conclude therefore 

 that the manifestation of the changes luhich underlie the after- 

 current is quite independent of the persistence of contractility 

 and conductivity. 



This does not, however, exclude the view by which positive 

 anodic, and negative kathodic, after -currents are regarded as 

 the consequences of break and make excitation, but may be 

 brought into agreement with it, if the possibility of localised 

 excitation without simultaneous change of form in the muscle 

 is admitted. This possibility is the less to be doubted since 

 the same phenomena also appear under perfectly normal con- 

 ditions. We need only refer to the fact that with direct 

 electrical excitation of the muscle there will always be a limit 

 of strength of stimulus below which the current no longer 



