EFFECT OF REPETITION 363 



The mean critical value for all the various plants 

 examined is 31-8°, the maximum variation from this is 

 less than 1°. It is very remarkable that the critical angles 

 for different plants should exhibit so close an agreement. 



The Effect of Repetition 



Experiment 196. — It was stated at the outset that 

 repetition of the experiment might reduce the friction and 

 diminish the critical angle. It is very interesting that this 

 should have been found to be actually the case. I took 

 three different specimens of the petiole of Tropaeolum, the 

 experiments being carried out three times in succession. In 

 every case it was found that the effect of repetition was to 

 produce a not inconsiderable lowering of the critical angle. 

 In the first specimen the critical angle was lowered from 

 32-5° to 28-5°, in the second from 31° to 22-5°, and in the 

 third from 30° to 22-5°. 



Table XXXIII. — The Effect of Repetition ox the Critical 



Angle. 



These experiments offer a very strong confirmation of the 

 statolithic theory. The fact that when the organ is gradually 

 inclined from the vertical there is no excitation till the critical 



