ii2 RESPONSE IN THE LIVING AND NON-LIVING 



galvanometer 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. 



It 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 2 C0 3 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 



