122 THE NATURE OF THE 



case the excitation would be reinforced, in the second weakened. 

 But I can scarcely believe that Hermann will still maintain this 

 theory of polarisation-increment now that Tigerstedt 1 has clearly 

 shown by unimpeachable methods that an excitation which has to 

 pass the cathode is never weakened, but always reinforced, and that 

 the theory of polarisation-increment is therefore incorrect. 



I come now to an additional point which is of importance in 

 explaining- the imperfect break-excitation : this concerns the time 

 during which the whole current passes along the nerve before 

 being reduced to a fraction of its strength. Since a nerve is an 

 organ which becomes strongly polarised, it is intelligible, and has 

 besides been directly demonstrated by du Bois-Reymond 2 , that a 

 constant current passing through a nerve is weakened by internal 

 polarisation, and, within certain limits, is the more weakened the 

 longer it passes. Although in the latter case the exciting current 

 has already diminished in strength when it is suddenly diminished 

 to a fraction of its height, the fall is no greater than in the case 

 in which there has been no previous diminution. Consequently 

 the same amount of anelectrotonus would disappear in each case, 

 and if this disappearance of anelectrotonus caused the excitation, the 

 fact that differences in the duration of closure affect the break- 

 contraction, which they do very considerably, would be unintel- 

 ligible 3 . The duration of closure has just as much influence on 

 the appearance of the incomplete break-contraction as it has on 

 that of the complete break-contraction. The longer the current 

 remains closed, the earlier do they both appear. That is to say, 

 with a long closure the imperfect break-contraction appears with 

 quite a small fall as compared with that which is necessary with 

 a short closure. According to Hermann's theory this is not intel- 

 ligible, but according to ours it is readily so. For with a longer 

 closure the polarisation-current which is unmasked is stronger 

 than with a shorter closure. 



The duration of closure varied in our experiments between \, I, 

 and 3 seconds, and the results in each case were in accordance 

 with theory. 



A few words in conclusion as to the influence of current- 

 strength on the appearance of imperfect break-contractions. It 



1 Above, pp. 20, 21. 



3 Gesammelte Abhandlungen, ii. p. 256. 



8 This reasoning of course applies also to the case of the complete break-contraction. 



* [In the original this statement is illustrated by a diagram. ED.] 



