KATHODIC POLARISATION OF MUSCLE. 337 



retarded, and in which the gradually increasing relaxation is de- 

 ferred for several seconds. 



If in such a case, after the maximum of shortening has been 

 reached, a battery current of medium strength (say two Daniells) 

 is closed for 1-2 sees., especially if it be ascending, there is observed 

 almost without exception an elongation of the muscle which is 

 sometimes rather considerable. This elongation coincides in time 

 with the moment of closure, and betrays itself by a sudden steep 

 fall of the curve. Whilst the closure lasts, the curve either con- 

 tinues horizontal or shows a slight inclination towards the abscissa, 

 and falls again more steeply only after the current is opened. It is 

 the exception under these circumstances, to observe on opening the 

 exciting current, a feeble renewed rising of the curve as an expres- 

 sion of the opening excitation of the muscle. 



If the current is closed at a time when the muscle is no longer 

 at its maximum shortening, then as a rule, a more or less evident 

 closing contraction is observed. If the same excitation is repeated, 

 by closing the current for a short time in unchanged direction 

 at different phases of the shortening and renewed lengthening of 

 the muscle, it is then seen that its proneness to excitation at closure 

 is generally diminished in proportion to the degree in which it 

 is shortened at the time of excitation. But even the completely 

 relaxed muscle immediately afterwards scarcely responds to the 

 same stimulus which shortly before produced a powerful contraction. 

 In the majority of cases, however, the increase of the results of 

 closing excitation keeps pace exactly with the gradually increasing 

 relaxation of the muscle, so that closing twitches produced during 

 relaxation at equal intervals, which almost always pass away 

 rapidly, all rise to the same height above the line of descent of 

 the curve which the muscle would have drawn had it been only once 

 excited. Tick also made analogous observations of a frog's muscle 

 poisoned with veratrine, by indirect excitation through the nerve, 

 and I shall return to these presently. 



If we observe more closely a veratrine muscle when in persistent 

 contraction during electrical excitation, we easily see that the 

 above described relaxation revealing itself in the curve by an 

 almost rectangular descent when the current is closed, constitutes 

 essentialy a local phenomenon, and indeed one confined to the 

 immediate neighbourhood of the anode, with which moreover the 

 small amount of descent in comparison with the total height of 

 the curve is in agreement. 



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