INTENSITY AND DURATION 



6:^ 



The noi-mal rate was restored after 5 minutes. The in- 

 tensity of current was next raised from 0-25 unit to i unit. 

 The second record shows that the latent period was reduced 

 to 4 seconds, and a relatively greater retardation of growth 

 occurred under the action of the stronger stimulus. The 

 recovery to the normal rate was not attained until after a 

 period of 10 minutes. The intensity of stimulus was finally 

 raised to 3 units ; the latent period was now reduced to 

 I second ; -the retardation induced was so great as to cause 

 a temporary arrest of growth. 



Table VII. — Time-Relatioxs of Responsive Growth-Variation 

 UNDER Electric Stimulation (Crinum). 



Intensity of 

 stimulus 



0-25 unit 



I -o 



^•o units 



Latent period 



8 seconds 



I second 



Normal rate 



0-62 fx per second 



0-62 ,« ,, 



0-62 



/^ 



Retarded rate 



O 



•49 /'. per second 



0-25 ,« ,. 



Temporan- arrest of 

 growth 



Effect of Intensity and Duration of Stimulation 



In the last experiment the effect of increasing intensit}^ 

 of stimulation in shortening the latent period and in pro- 

 longing the period of recovery was observed. In the two 

 following experiments the effect of increasing intensity 

 and duration of stimulus was the special object of investiga- 

 tion. The specimens employed were the buds of Crinum 

 Lily, which were subjected to successive increase of intensity 

 of stimulation. After each record sufficient time was 

 allowed for recovery before application of the next 

 stimulation. 



Experiment 34. Effect of increasing intensity of stimula- 

 tion. — The duration of the stimulation, which was 5 seconds, 

 was kept the same in successive records, the intensity being 

 increased from i to 2, and finally to 4 units. The normal 



