io6 RESPONSE IN THE LIVING AND NON-LIVING 



on the circuit containing 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, b). 

 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. 



FIG. 61. PROLONGATION OF PERIOD 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 



