in ELECTRICAL EXCITATION OF MUSCLE 227 



There must, therefore, in the continuity of a muscle, be some 

 specific relation at the limit letiveen dead and living fibres, which 

 is capable of inhibiting excitation. 



The simple experiment of reversal of current proves that 

 the total excitability of the muscle is not injured by destruction 

 of one end, but there is reason to suppose that excitability, 

 in the immediate proximity of an injured part is more or less 

 diminished. This appears indeed to be contradicted by the 

 experiment of bringing the epiphysis of the tibia (or of the 

 pelvis, if the upper end of the sartorius is injured) into relations 

 of conductivity with some point on the surface of the muscle, by 

 means of a bridge of salt clay, beyond the injured part ; the 

 muscle will contract almost as sharply at closure of a descending 

 (or ascending) current as before the injury : but it must be 

 remembered that, according to all probabilities, the condition of 

 acute depression of excitability is confined to the immediate 

 proximity of the point injured ; at all events this must occur 

 immediately after the ends of the fibres have been crushed on the 

 one side. That excitability must, generally speaking, be diminished 

 at the border between dead and living fibres, follows from the 

 fact that the process of dying invades the entire length of a fibre 

 continuously, when once it has been introduced at any point ; 

 accordingly dead arid living fibres are never in immediate juxta- 

 position, but the section of the muscle that has been structurally 

 disturbed by the attack, and killed, must in the adjacent sections 

 initiate every possible process of dying, and correlative state of 

 excitability, as has already been pointed out by Hermann. 1 



If it is true, as stated above, that the extension of " local 

 fatigue " is important in determining whether an electrical 

 stimulus of given magnitude does or does not produce change 

 of form in the muscle, we may .presume that the slow dying 

 of one or the other end of the sartorius, on immersion in warm 

 water, depresses the excitability of the muscle to one direction 

 of the current more completely than simple mechanical injury : 

 it cannot be doubted that the local, slowly-increasing effect of rising 

 temperature is able to produce complete gradation of excitability 

 in the sections of the muscle proximal to the section in heat- 

 rigor. This view is confirmed experimentally (supra). 



1 Hermann, Weitere Unters. z. Phys. d. Nerven u. Muskeln. Berlin, 1867, 

 p. 5 f. 



