102 INTRODUCTION. 



only when the electrodes are at a moderate distance (5 to 7 mm.) 

 apart. With the electrodes closer there is no difference observable, 

 or there may even be a difference in the opposite direction. With 

 the electrodes at indifferent points we have, as might be expected, 

 never been able to observe a difference in the above sense. Con- 

 tractions begin with exactly the same current strengths, whether 

 the current is opened and closed in the main or in the nerve- 

 circuit. 



THE BKEAK-EXCITATION. 



IT had thus been shown and therefore I referred to these 

 experiments again here that (i) a large class of break-excitations 

 are only so apparently, and (2) that the excitation of a particular 

 set of fibres in a nerve-trunk may be due to the closure of a 

 current in the substance of the nerve, independently of the existence 

 of an external arc of connection. Since, further, I had by earlier 

 experiments convinced myself that (3) in the case of currentless 

 nerve or muscle preparations excitation either does not occur at 

 all at break, or only with very strong currents, there naturally 

 arose a doubt in my mind as to whether the disappearance of an 

 electric current ever excites a nerve or muscle ; whether, to speak 

 with Pfliiger, the disappearance of anelectrotonus does in reality 

 produce an excitatory effect. I now think that this is not the 

 case, and believe, moreover, that there is no break-excitation, but 

 that every so-called break- excitation is in reality a make-excitation. 



Before, however, I say anything as to my reasons for this belief, 

 I wish to express my pleasure on finding that about the same time 

 R. Tigerstedt 1 arrived at exactly the same conclusions, from 

 similar experiments and reasoning. This fact points, I think, 

 with a certain probability to our mutual view of the matter being 

 the right one. As Tigerstedt's work is doubtless accessible and 

 known to the readers of this paper, I can pass more rapidly over 

 many points, and refer the reader to that work. 



Apart from the mention of the matter by Peltier 2 , du Bois- 

 E/eymond 3 , as is well known, was the first to prove by unimpeachable 

 experiments that in a nerve or muscle through which a current has 

 been passed there is afterwards a current in the opposite direction. 



1 See No. Ill of these Translations, of which the original appeared two or three months 

 after the author's preliminary paper (Breslauer arztliche Zeitschrift, No. 23, 1882). 



2 Untersuchungen uber thierische Elektricitat, i. p. 376, 1848. 

 9 Ibid. p. 377. 



