EFFECT OF TEMPERATURE 61 



the series taken. It should be mentioned that in all these 

 cases the stimulus employed was of constant intensity — 

 namely, 2. 



In fig. 27 are shown the responsive effects of an identical 

 stimulus at these three different temperatures. At 22° C. 

 it is seen that the height of response is small and the recovery 

 extremely prolonged. At 27 C. we find the amplitude of 

 response enhanced and the rate of recovery increased. At 



Fig. 28. — Response taken at three different temperatures, 

 the lowest below and the highest above, on a faster- 

 moving plate ; amplitude of response larger and 

 steepness of curve greater, at higher temperature. 



32° C. the height of response is still more enhanced and the 

 rate of recovery, as seen in the steepness curve, still further 

 increased. In fig. 28 is given another set of records taken 

 on a faster-moving plate, exhibiting the effect of tempera- 

 ture on the amplitude of response. It will be shown in a 

 succeeding chapter that the latent period also is affected, 

 being progressively decreased with rising temperature. 



Influence of Stimulus-intensity on the Response 



It is usually supposed that in Mimosa every effective 

 stimulus causes the maximum response. That this is not 

 the case comes out very clearly in careful records taken 



