STIMULUS AND RESPONSE 63 



being very slight. After the seventh, it was found that the 

 responses did not undergo any further increase. 



The range within which the increasing effect is seen 

 is relatively extended in the case of plants in a somewhat 

 sub-tonic condition. But when the specimen is highly 

 excitable the range of variation is proportionately restricted. 



Summary 



The break-shock is more effective in inducing excita- 

 tion than the make-shock. 



Stimulus, singly ineffective, becomes effective on repeti- 

 tion. The effective stimulation is equal to the individual 

 intensity of stimulus multiplied by the number of repetitions. 



The effect of load on the response of Mimosa is similar 

 to that on the contractile response of muscle. With 

 increasing load the height of response undergoes a progres- 

 sive diminution with shortening of period of recovery. 



Within Umits, the amount of work performed by a 

 muscle increases with the load. The same is true of work 

 performed by the pulvinus of Mimosa. 



In a given case the rate of work performed by the pul- 

 vinus of Mimosa was 7480 mm. mgrms. per second. 



The effect of rising temperature on response is to enhance 

 the amplitude and to shorten the period of recovery. 



In Mimosa, increasing intensity of stimulus induces 

 increasing amplitude of response. This, however, soon 

 reaches a limit. 



