40 
The magnitude of the katelectrotonic effects will depend 
upon the magnitude of the threshold number ( (i). If only 
a part of the kations liberated at the kathode by a current is 
discharged, there will be improvement in excitability, con- 
ductivity, and "negativity" at the kathode, owing to the 
influence of the free kations ; this will be the case when (i is 
small, and occurs, as we should expect, in medullated nerve.* 
But where (3 is large, and the ion-proteid therefore more 
stable, a very large proportion of the electrolysable portion 
of the ion-proteid is used up in initiating the discharge, and 
therefore the proteid residues at the kathode, after discharge, 
are great in proportion to the free kations, and their delay- 
ing effect neutralises the improving effect of the kations, as 
is the case in non-medullated nerve, where, as we have seen, 
/3 is greater than in medullated nerve, and there is no 
katelectrotonus.f. If y8 be larger still the effect of the proteid 
residues is to reverse the improving effect that would other- 
wise be produced by the kations. This is the case in muscle, 
as we have seen, and in muscle /5 is greater than in nerve. % 
The magnitude of the anelectrotonic effect depends on th.', 
amount of anion-proteid, but since no anions are discharged 
until break it should, in general, be greater than the katelec- 
trotonic effect, and this is, in fact, the case. S In further 
support of our theory of katelectrotonus, we may allude to 
the fact that with strong currents of long duration conduc- 
tivity is retarded at the kathode even in medullated nervelj 
owing to the greater amount of electrolysis and the gradual 
diffusion of kations from the kathodic points, leaving behind 
the indiffusible proteid residues. 
Since there is less anion-proteid than kation-proteid 
anelectrotonus develops more slowly than katelectrotonus, 
hence "currents of moderate strength but of short duration 
excite only on closure, i.e., at the kathode." 51 Given the 
facts of electrotonus, Pfliiger's law of contraction follows. 
* Vide Gotch : Schafer's Textbook of Physiology, vol. ii., 
pages 494 and 502 ; and Biedermann : Electro-phvsiology : Trans, 
by F. A. Welby, vol. ii., page 268. 
t Biedermann : Electro-physiology: Trans, by F. A. Welby, 
vol. ill., page 284. 
X Vide section 8, this paper. 
§ Biedermann : El©ctix)-physiology : Trans, by F. A. Welby, 
vol. ii., page 268. 
II Ibid., vol. ii., page 148. 
IF Got oh : Schafer's Textbook of Physiology, vol. ii,, page 506. 
