270 ELECTRO-PHYSIOLOGY CHAP. 



in succession without disturbing the electrodes : first, for a 

 moment only, to produce sustained contraction of the vera- 

 trinised sartorius ; and secondly, for longer, in order to observe 

 the local relaxation at the anode. 



If the normal muscle in situ is stimulated with unipolar 

 excitation, the difference between kathodic and anodic effects is 

 strongly marked, even with the weakest currents. While with 

 punctiform contact of the muscle surface with the kathode, a 

 local persistent contraction appears at the point of contact only, 

 (after the make twitch has subsided), while the rest of the surface 

 remains perfectly even, stimulation with the anode produces in 

 consequence of the persistent excitation in the bundles of fibres 

 on either side of the point at which current enters a deep, 

 permanent, longitudinal furrow upon the surface of the muscle, 

 while the actual point of contact and its immediate neighbourhood 

 remains unexcited, and more or less extended, so that a flat, 

 dinted constriction appears. 



With this mode of excitation the break effect shows very 

 plainly as a small swelling, which appears at the point where the 

 current enters, as soon as the circuit is broken, and remains 

 visible for a long period. The similarity between this re- 

 action in striated skeletal muscle, and the effects of electrical 

 excitation in smooth muscle discussed above, is undeniable, so 

 that the presumption of a fundamental uniformity in the response 

 of these two kinds of muscle, as well as of cardiac muscle, to the 

 electrical current, can hardly be disputed. This applies both to 

 the manifestations of polar excitation, and the equally polar 

 effects of inhibition. When it is remembered that the manifesta- 

 tions of excitation near the anode only appear with weak 

 currents, on " unipolar " excitation, and, as found from recent 

 experiments, fail altogether if the muscle (sartorius) dips 

 into fluid, and is longitudinally traversed appearing only 

 at a high intensity of current, notably when the direction is 

 ascending, if the preparation is stretched in Hering's double 

 myograph it can hardly be doubted that we are again in face of 

 excitation effects at secondary kathodic points, the existence of 

 which, with unipolar excitation, is self-evident, but which must 

 also be present, more particularly at the knee end of the 

 sartorius, when current is sent in from the stumps of bone behind 

 it. This is the necessary consequence of the peculiarly graduated 



