106 RESPONSE IN THE LIVING AND NON-LIVING 
on the circuit contaiming the cell. (2) A record was 
next taken of the E.M. variation produced in the cell 
by a single stimulus. It will be seen on comparison of 
the two records that the maximum effect took place 
relatively later in the case of mechanical stimulus, and 
that whereas the galvanometer recovery in the former 
case took place in 11 seconds, the recovery in the 
latter was not complete till after 60 seconds (fig. 60, 0). 
This shows that it takes some time for the effect of 
stimulus to attain its maximum, and that the effect does 
not disappear till after the lapse of a certain interval. 
The time of recovery from strain depends on the 
intensity of stimulus. It takes a longer time to 
recover from a stronger stimulus. But, other things 
being equal, successive recovery periods from suc- 
cessive stimulations of equal intensity are, generally 
speaking, the same. 
We may now study the influence of any change in 
external conditions by observing the modifications it 
produces in the normal curve. 
° 
40 
(a) 




BTS dO" | SUE OO ae eae 
Fic. 61.—Protoncation oF Prertop oF REcovERY AFTER OVERSTRAIN 
Recovery is complete in 60” when the stimulus is due to 20° vibration. But 
with stronger stimulus of 40° vibration, the period of recovery is prolonged 
to 90”. ‘ 
Prolongation of period of recovery by overstrain.— 
The pair of records given in fig. 61 shows how 
