324 THE SO-CALLED SECONDARY ELECTROMOTIVE 



have learnt that the former rapidly disappears, the latter remains 

 for some time persistent ; and, further, that the latter is preceded 

 by a rapid + condition, which is the polarisation-current of the 

 anodal extrapolar region. Moreover, we have established the same 

 laws for the phenomena in muscle also. There is here only a 

 quantitative difference. In nerve the anodal action-currrent is 

 so strong that, although it has to contend with a + polarisation- 

 current, it is still able to exceed in magnitude the undiminished 

 + polarisation-current of the kathodal region. In muscle this is 

 not the case ; the action-current is indeed strong, but when weak- 

 ened by the polarisation-current, it sinks below the magnitude of 

 the full polarisation-current of the other region. In the schema 

 (given under C) this may be indicated by stating that in nerve 

 a" p' > p", or if p' = p", then a' > 2 p' ; whilst in muscle, a' p' < p", 

 or a' < 2 p'. The weak development of the extrapolar breaking- 

 excitation in muscle may be due either to a weak development 

 or to a rapid disappearance of the anelectrotonic state. It is note- 

 worthy that we find the intrapolar spread of anelectrotonus to be 

 less in muscle than in nerve. 



In his second publication, on the extrapolar after-currents of 

 nerve, Tick suggests that the kathodal after-current, which he had 

 stated in his first communication to be, like the anodal, might 

 possibly be in the first moment after opening, and then + , thus 

 being double in character. This suggestion now appears to be a 

 faulty one. As a matter of fact it is the anodal and not the 

 kathodal-current which is double in character, being first + and 

 then . We are able now to substitute for the view, which 

 led Fick to this suggestion, something more certain, viz. the 

 complete explanation of the causal relations. 



Finally, we obtain some explanation of a long-known pheno- 

 menon. Pfliiger by excitatory 1 , and du Bois-Reymond 2 by gal- 

 vanometric methods, found that during the closure of a polarising- 

 current the extrapolar anelectrotonic state tends to increase, the 

 catelectrotonic state to decrease. This may be now fully explained 

 as follows. The extrapolar polarisation (as in the metal and fluid 

 envelope schema, vide Pfliiger, 'Archiv,' vol. vi. p. 320) must 

 strengthen the extrapolar currents on both sides the longer it 

 continues. On the side of the kathode, however, we have at the 

 commencement of closure an action-current of similar direction 



1 ' Untersuchungen tiber die Physiologic des Electrotonus,' p. 319. 



2 'Archiv ' f. Anat. u. Physiol. 1867, p. 441. 



