KATHODIC POLARISATION OF MUSCLE. 343 



by veratrine on the one hand, and the tonically shortened adductor 

 muscle of Anodonta and the systolically contracted heart on the 

 other. This assumption is further materially supported by the 

 agreement which, as will be shown, exists in regard to secondary 

 electromotive phenomena, between the muscle of Anodonta and 

 striated muscle poisoned with veratrine. 



3. The secondary electromotive phenomena of veratrine 

 muscle excited electrically. 



Du Bois-Reymond 1 has already occupied himself with the ex- 

 perimental solution of the question, how the polarisation phenomena 

 of striated muscle behave during tetanic excitation, and arrived at 

 the result, that ' tetanised muscle undergoes less strong (positive) 

 polarisation than muscle in repose.' 



I also now directed my attention to the investigation of the 

 secondary electromotive phenomena of a muscle tetanised through 

 the nerve, and I selected the sartorius as the object presumably 

 best fitted for the purpose. However I soon became con- 

 vinced that satisfactory results are hardly to be expected in this 

 way, because it proved that as a rule, the strength of tetanus is 

 maintained at the same point, too short a time to allow of ex- 

 perimenting with sufficient certainty. Moreover it seemed 

 desirable to replace the discontinuous tetanus by a more constant 

 condition of excitation comparable to tonus, and I therefore had 

 recourse again to the means of poisoning with veratrine already 

 tried. 



The method of poisoning the entire muscle through the cir- 

 culation had proved best adapted for the investigation of the 

 variations of form on electrical excitation, but it is less fitted in a 

 case like the present, when the results of the excitation have to 

 be examined by means of the galvanometer. The chief reason for 

 this is, that the force of the excitation, as well as its period of 

 passing away, are presumably not quite the same at all points, and 

 hence there will be differences of tension in the continuity of 

 the muscle ; these do not admit of being estimated, and make it 

 impossible to interpret the result of the observation with certainty 

 in each case. I have therefore since adopted exclusively local 

 poisoning of the muscle by direct application of a correspondingly 



1 See No. V. of this work. 



