434 THE PROPERTIES OF STRIPED MUSCLE. 



protracted one which does not spread. A change of an opposite nature 

 has been described at the anode ; a slight depression presents itself at 

 the surface of contact, on either side of which the streaks sweep in 

 curves. 



The conditions under which the cathodic persistent contraction 

 presents itself have not as yet been sufficiently studied. The utmost 

 that can be said on the subject is, that the appearance of this phenomenon 

 is favoured by any cause which tends to diminish the promptitude with 

 which the muscular elements directly excited respond to the stimulus, 

 as well as the readiness with which the excitatory state is taken up 

 from them by neighbouring elements. The best known of the con- 

 ditions in question is that of cold. In the sartorius of a frog which 

 has been kept at a temperature a little above that of freezing, as 

 Hermann has shown, the cathodic continuous contraction is very readily 

 produced. 



The anodic dosing contraction. It occasionally happens, when a 

 current of considerable strength is led through the sartorius from the 

 tibial to the pelvic end, that a contraction appears at the anode 

 simultaneously with that at the cathode. When the pelvic end is injured, 

 so as to annul the cathodic effect, this contraction is more obvious, 

 and has been recorded graphically by Biedermann. By careful obser- 

 vation with the lens, Biedermann has satisfied himself that the seat 

 of 'contraction is a part of the muscle between the anode and the 

 middle, and that in fact the fibres at the anode itself are relaxed. 

 A similar appearance presents itself when the current is led in by the 

 anode only, the cathode being at a distance. Biedermann no doubt 

 rightly attributes this phenomenon to the passing of threads of current 

 from one muscular fibre to another. It derives special interest from its 

 connection with a much more striking effect of very strong currents on the 

 sartorius the galvanic wave. By this is meant that when a very strong 

 current is led through the sartorius, visible waves of contraction follow 

 each other in the direction of the current with a peculiar surging motion. 

 This only happens when the muscle is in a good state and its fibres are 

 relaxed so as to be more or less wavy. Professor Hermann, who has 

 studied the phenomenon minutely, has no doubt that this, like the anodic 

 closing contraction just referred to, is due to want of conformity between 

 the threads of current and the muscular fibres, and that although each 

 wave starts from near the anode, its origin at any point in a muscular 

 fibre is in reality cathodic, for it is determined by the passing out of the 

 fibre of a thread of current. 



Influence of currents led through muscular fibres transversely. If, 

 as appears from the facts we have had before us, the actions of the 

 two poles are antagonistic to each other, so that the exciting effect of 

 the cathode is " inhibited " by the quelling effect of the anode, we should 

 expect to find that neither of these effects could be produced on any 

 muscular element, unless the direction of the current either coincided 

 with that of the axis of the element or crossed it obliquely. For, if it 

 crossed it transversely, the action of the two poles would neutralise one 

 another. In other words, we should expect that if the current threads 

 were parallel to each other, and the fibres of the muscle were also parallel, 

 a current led across a muscle would have no effect whatever. The 

 difficulty of testing this anticipation by experiment is so great, that 

 there has been considerable difference of statement with reference to it. 





