in ' ELECTRICAL EXCITATION OF MUSCLE 253 



battery current that the muscular tube contracted at the spot 

 in contact with the kathode, after a shorter or longer, but always 

 directly perceptible, latent period, while the whole intrapolar 

 area, as well as the anode, remained quiescent at the same time. 

 Immediately after, a wave of contraction (similar to that which 

 follows on localised mechanical excitation) starts from the. 

 kathode, in both the peristaltic and the anti-peristaltic direction. 

 Just as the make excitation starts from the kathode, Engeln^ann 

 found that the break excitation proceeds exclusively from the 

 anode : the contraction always begins exactly at the point where 

 current had previously entered the ureter through the electrode, 

 never at the same moment in any larger area of the tract 

 traversed. Here, as in striated muscle, the opening of the 

 constant current is usually a weaker stimulus than its closure, so 

 that greater intensity of current, and longer closure in particular, 

 is required to produce any visible consequences. According to 

 Engelmann, induced currents work exactly like constant currents 

 of very short duration (current impacts), i.e., as a rule, they 

 only act as make stimuli, in which excitation proceeds from the 

 kathode. It is only with very high excitability, and currents of 

 great strength, that the contraction appears under certain condi- 

 tions to begin at both poles simultaneously. 



If in the guinea-pig, or rabbit, the two electrodes are applied, 

 after removing the viscera, to different points of the ureter in 

 situ, or if one electrode only is brought into contact with any 

 given point, the other being applied to some indifferent part of 

 the body, the excitation at closure will invariably proceed from 

 the anode. Under such conditions there is never kathodic 

 closure, or anodic opening, excitation. 



With both the weakest and strongest possible currents, 

 and, as a rule, independently of the position of the electrodes, 

 and the direction of the current, the ureter is always con- 

 stricted first at the anode, on closing the circuit, after which the 

 wave progresses in both directions as described by Engelmann. 

 The same applies to the break excitation, which after prolonged 

 closure, with sufficiently strong currents, appears at the kathode. 

 The nature of the contraction leaves no doubt that there is in 

 both cases simultaneous excitation of the circular and longitudinal 

 muscles. The smallness of the object makes it difficult to decide 

 with certainty whether the closure contraction really proceeds 



