112 RESPONSE IN THE LIVING AND NON-LIVING 
ealvanometer deflection is ‘ up’ when A alone is excited, 
the excitation of B will give rise to a downward 
deflection. When the two points are simultaneously 
excited the electric variation at the two points will 
continuously balance each other. Under such conditions 
there will be no resultant deflection. But if the intensity 
of stimulation of one point is relatively stronger, then 
the balance will be disturbed, and a resultant deflection 
produced whose sign and magnitude can be found 
independently by the algebraical summation of the 
individual effects of A and B. 
Tt has also been shown that a balancing point for 
the block, which is approximately near the middle of 
the wire, may be found so that the vibrations of A and 
B through the same amplitude produce equal and 
opposite deflection. Simultaneous vibration of both will 
give no resultant current; when the block is abolished 
and the wire is vibrated as a whole, there will still be no 
resultant, inasmuch as similar excitations are produced 
at A and B. 
After obtaining the balance, if we apply an exciting 
reagent like Na,CO, at one point, and a depressing reagent 
like KBr at the other, the responses will now become un- 
equal, the more excitable point giving a stronger deflec- 
tion. We can, however, make the two deflections equal 
by increasing the amplitude of vibration of the less 
sensitive point. The two deflections may thus be ren- 
dered equal and opposite, but the time relations—the 
latent period, the time rate for attaining the maximum 
excitation and recovery from that effect—will no longer 
be the same in the two cases. There would therefore 
