VARIOUS TYPES OF RESPONSE 



93 



the new stimulus with its opposing impulse was received. 

 There is thus a diminution of height in the resultant 



I 



^i ^i ^ ^( 



FIG. 59. Record showing Diminution of 

 Response, when sufficient Time is not 

 allowed for Full Recovery 



In (a) stimuli were applied at intervals of one 

 minute ; in (b) the intervals were reduced 

 to half a minute ; this caused a diminution 

 of response. In (c) the original rhythm is 

 restored, and the response is found to be 

 enhanced (Radish). 



FIG. 60. Fatigue in 

 Celery 



Vibration of 30 at in- 

 tervals of half a minute. 



response. The original rhythm of one minute was now 

 restored, and the succeeding records (fig. 59, c) at once show 

 increased response. 



Residual strain is thus seen to 

 be one of the principal reasons of 

 reduced response or fatigue. This 

 is also shown in a record which 

 I have obtained with a petiole of 

 celery (fig. 60). It will be noticed 

 there that, owing to imperfect 

 molecular recovery, during the 

 time allowed for rest, the heights 



of succeeding responses Undergo Stimulus : 30 vibration at interval 



a continuous diminution. Fig. 6 1 



gives a photographic record of 



fatigue in the petiole of cauliflower, and fig. 62 of fatigue in 



inorganic response. 



It is evident that residual strain, other things being equal, 

 will be greater if the stimuli have been excessive. This is 



FIG. 61. 



Fatigue in Leaf-stalk of 

 Cauliflower 



