6 RESPONSE IN THE LIVING AND NON-LIVING 
similar changes taking place at both points, and there 
being thus no relative difference between the two, the 
galvanometer will still indicate no current. This null- 
effect is due to the balancing action of B as against A. 
(See fig. 2, a.) 
Conditions for obtaining electric response.—If then 
we wish to detect the response by means of the galvano- 
meter, one means of doing so will lie in the abolition of » 
this balance, which may be accomplished by making 
one of the two points, say B, more or less permanently 

--- Ser of cloth 
| morstened withNall solution 
<— Current of Ingury 
—> Current of Action 
Fic. 2.—Enecrric Meruop or Dretrectinc NERVE RESPONSE 
(a) Iso-electric contacts; no current in the galvanometer. 
(6) The end B injured; current of injury from B to A: stimulation gives rise to 
an action current from A to B. 
(c) Non-polarisable electrode. 
irresponsive. In that case, stimulus will cause greater 
electrical disturbance at the more responsive point, 
say A, and this will be shown by the galvanometer as a 
current of response. To make B less responsive we 
may injure it by means of a cross-sectional cut, a burn, 
or the action of strong chemical reagents. 
Current of injury.—We shall revert to the subject of 
electric response; meanwhile it is necessary to say a few 
words regarding the electric disturbance caused by the injury 
itself. Since the physico-chemical conditions of the uninjured 
A and the injured B are now no longer the same, it follows 
