294 ELECTRO-PHYSIOLOGY CHAP. 



3 mm. long, upon the conduction of a wave of excitation set up 

 beyond its limits. He found that the conductivity of the 

 polarised section of the muscle diminished in proportion with 

 the strength of current and length of its passage. At a given 

 degree of polarisation, the power of conducting seemed to be 

 completely abolished. (This, e.g., was the case after the current 

 from 4 Dan., with a rheochord resistance of 100, had been sent 

 through a tract of muscle 3 mm. long, for 40 sees.) Von Bezold 

 affirms that the substance of muscle, like that of nerve, is 

 " paralysed " by the current. This paralysis he describes as a 

 defect, or inhibition, of conductivity, although the apparent injury 

 to the muscular tract does not prevent it from being thrown into a 

 state of local excitability by external stimuli as rapidly as before. 

 Von Bezold did not inquire into the reaction of different sections 

 of the intrapolar tract with reference to changes in conductivity, 

 but he inclines to the view " that the curve of defect in the intra- 

 polar tract, as in the parallel case of nerve, sinks from either pole 

 towards the middle." 



It is the more advisable in this connection to investigate 

 Engelmann's experiments on the effect of polarisation upon the 

 conductivity of smooth muscle, because while there are manifold 

 analogies between the smooth muscle of the ureter and striated 

 muscle, as regards response to the electrical current, there 

 appear in this instance to be essential differences between the 

 data obtained by the author from striated muscle, and Engel- 

 mann's observations on the ureter. 



He finds that conductivity in a polarised tract of ureter 

 diminishes in the side towards the anode, and increases in that 

 towards the kathode. The magnitude of the changes is maximal 

 at the poles. The length of the area of depression increases 

 with strength and intensity of current, conduction being finally 

 abolished in the whole intrapolar tract. "When the wave of 

 contraction started from a point above an ascending polarised 

 section of the ureter, Engelmann observed that it traversed the 

 entire intrapolar tract if the polarising current was very weak 

 though with a marked diminution at the anode. With strong- 

 currents the wave disappeared altogether at this point, and with 

 still stronger (persistent contraction at the kathode), it died out 

 even at the kathode. 



With regard, firstly, to v. Bezold's experiments, they by no 



