342 INHIBITION BY EXCITATION AND 



which is primarily local. The elongation which takes place in 

 a muscle which is in the state of persistent opening- contraction, 

 when the current is closed in the same direction as before, has 

 been long- known to occur, and must certainly be considered as a 

 kindred phenomenon ; the only difference is, that the question here 

 concerns the inhibition of a condition of excitation produced at 

 the physiological anode, by the after-effect of the current previously 

 flowing through the muscle. 



Notwithstanding the great sensitiveness of the veratrine muscle 

 in repose, to the closing excitation, yet in general this excitation 

 develops effects so much the feebler as the muscle remains more 

 forcibly contracted at the time of excitation ; now and then, after 

 the return of complete expansion, it fails to produce any effects. 

 Considering these facts, there seems in this behaviour a further 

 analogy with systolically contracted cardiac muscle, and especially 

 with the tonically shortened muscle of Anodonta. In the case 

 of the former, Marey 1 showed that it is during systole quite unex- 

 citable by feeble stimuli which are capable of exciting the diastolic 

 heart to contraction, and that this excitation occurs the more readily 

 the later the stage of relaxation in which it acts. This recalls 

 directly the observation of Fick 2 , already mentioned, that in indirect 

 rhythmical excitation of a veratrine muscle in persistent contraction, 

 all the twitches produced by it ' rise to very nearly the same height,' 

 so that all their base points lie in a curve, which, as it appears, 

 corresponds closely to the gradual re-expansion of the muscle after 

 the first twitch. 



In regard to the adductor muscle of Anodonta which consists of 

 smooth fibre cells, I have myself found, that in a state of tonic 

 contraction, it does not react sensibly even on very strong closing 

 excitation, although on opening the current it sometimes contracts 

 vigorously. On the other hand, when it is as much as possible 

 relaxed, it behaves in regard to the current (leaving out of con- 

 sideration the difference of period of the contraction) exactly like 

 a normal striated muscle, for then the sensitiveness to the closing 

 excitation is far greater than to the opening one. 



The facts already mentioned appear to speak very decidedly in 

 favour of the assumption, that in regard to the phenomena resulting 

 from electrical excitation, far-reaching analogies exist between 

 striated muscles of the trunk thrown into persistent contraction 



1 'Physiologic exp&dmentale (Travaux da laboratoire de Marey,' 1876, p. 63 f.). 



2 Loc. tit. p. 146. 



