viii.] INJURY CURRENT AND BLAZE-CURRENT 145 



it is known to us as a transmitted excitatory effect, whereas 

 the " blaze " is a direct excitatory effect. 



The fact that a blaze-current homodrome with its exciting 

 current, is obtained between two uninjured and iso-electric points, 

 signifies that in general the post-anodic homodrome is greater 

 than the post-kathodic antidrome current. There is an ex- 

 citatory state at both poles, greater at anode than at kathode, 

 and if the excitation be reversed, there is as before a homodrome 

 effect, but reversed with the reversal of excitation. If, before 

 applying the second stimulus, we shift one of the electrodes 

 that have served for the first stimulus and blaze, to a fresh spot 

 (or, better, if by the ABC plan we transfer the A or B con- 

 nections to a third indifferent point C), we shall find (on muscle, 

 on vegetables) that both A and B i.e., post-kathodic and post- 

 anodic points are zincative (electro-positive) to C. And if, now, 

 having compensated, we stimulate in either direction through 

 these points A C or B C, i.e., through one active point A or B, 

 and one passive point C, we shall arouse blaze in the tissue from 

 C to A or B. The first excitation has given blaze of A and B, 

 which are zincative (electro-positive) to C. The second excita- 

 tion has given a second blaze of either A or B, which is opposed 

 and greatly exceeded by the first blaze of the previously un- 

 touched C. We may regard the first current from A or B to C 

 as an injury current, and the second current from C to A or B 

 as its negative variation. 



So that in sum total we assimilate, as belonging to one class, 

 what has been variously designated blaze-current, injury current 

 (in so far as it is an irritation current), and action current. The 

 fact that a blaze-current is augmented where it occurs in the 

 same direction as a polarising current, is essentially similar with 

 the phenomenon known to you in nerve-physiology as the 

 polarisation increment. In the latter case, an active state sweep- 

 ing wave-like along a nerve undergoes a sudden increment on 

 reaching an anodic region, and the polarising current is in- 

 creased ; the anodic region, in which action is lowered, is 

 capable of great increase of action when it is aroused by the 

 transmitted excitation. It is more " zincable." In our case, 

 also, the anodic region of a polarising current is more " zincable," 



K 



