in ELECTRICAL EXCITATION OF MUSCLE 295 



means prove that the conductivity of the whole intrapolar tract 

 is diminished or abolished, it being indeed much too short. The 

 inhibition of the wave of contraction might equally have its 

 seat at the anode, if, as certainly appears from Engelmann's 

 experiments on the ureter, it is true that the conductivity of the 

 muscular substance is considerably depressed there as well as at 

 the kathode, since at the strength of the polarising current 

 employed a persistent contraction must in any case be present, 

 and since, as we may legitimately conclude from Engelmann's 

 observations, a contracted point may, under certain conditions, 

 interrupt the conductivity of excitation. 



The next point, therefore, was to test the conductivity of the 

 muscle-substance at the anode as well as at the kathode, and to 

 ascertain its dependence on the strength and duration of the 

 current. For this purpose a strongly curarised sartorius muscle was 

 connected in the usual manner with the unpolarisable electrodes 

 of Bering's double myograph, the centre of the muscle being fixed 

 with oil-clay, and the changes of form of both halves recording 

 themselves on a smoked surface. As a rule, the lower end of 

 the sartorius was excited with single descending make induction 

 shocks. The exciting current escaped by one electrode of the 

 double myograph ; its entry was arranged by a loop of thread, 

 moistened with 0'5 salt solution, and inserted into the 



clay tip of an ordinary unpolarisable electrode, in order to 

 obstruct the changes of form in either half of the muscle as little 

 as possible during excitation. In the immediate vicinity of the 

 fixed part, corresponding roughly with the centre of the muscle, an 

 electrode of the same kind enabled the polarising battery current 

 to leave or enter the muscle, the whole upper part of which was 

 traversed. A wave of contraction discharged at the lower end 

 of the sartorius traverses the fixed part without interruption, 

 and both halves of the muscle shorten, as a rule, approximately 

 so long as the polarising circuit remains open. Even a weak 

 galvanic current (ascending or descending) passing through the 

 upper half of the muscle continuously, exerts no perceptible 

 influence on the size of twitch in either half. When, however, 

 the intensity of the polarising current is raised (to about 2 Dan. 

 = 100 R), the kathode being in the centre of the muscle, a pro- 

 nounced inhibition, in proportion with the strength and direction 

 of the current, in every case interferes with the propagation of the 



