ANIMAL ELECTRICITY. LECTURE VI. I4I 



is at rest, I excite the nerve. There is a deflection 

 to the right, i.e., an increment of the polarising 

 current. 



Repeating the experiment with the reversed 

 direction of polarising current, everything is re- 

 versed, viz., this current is to the left, and its 

 excitatory variation Is also to the left. 



Trace out the rationale of the polarisation Incre- 

 ment in this form, and you will recognise that in both 

 cases the anodic portion of nerve, or "way in" of 

 current, being the more zincable spot, becomes more 

 zincatlve during the superadded state of excitation. 

 There is thus "current of action" in the same direc- 

 tion as polarising current. 



These varieties of effect in accordance with various 

 combinations of circuits, might readily be extended. 

 We might, e.g., test for the decrements of An. and 

 Kat. with the coil In the electrotonic and oalva- 

 nometer circuit, instead of in the polarising circuit. 

 Or going back to our second fundamental experi- 

 ment, as described In the first lecture — the negative 

 variation of nerve current (p. lo) — we might combine 

 Into one the leading-in and leading-out circuits. 



The results of such experiments would come out 

 precisely as might be anticipated. Wherever current 

 enters a nerve from an electrode, the nerve is anodic 

 and zincable, whether such current be a polarising 

 current sent into the nerve, or an electrotonic current, 

 or a current of injury drawn o^ from the nerve. 



