41^ Prof. Burdon- Sanderson and Mr. F. J. M. Page [Dec. 14, 



until both are in contact with the internal surface of each lobe close to 

 its border. All that remains is to fix a graduated arc against the lever, 

 to select a sensitive hair for excitation, carefully to touch it at regular 

 intervals, and to record the movements of the lever. Each approach of 

 the leaf is thus indicated in magnified proportion by the end of the lever. 

 The following Table gives the results of an obser\'ation made in this way. 



Table I. 



Showing the result of mechanical successive excitations of the hair y, at 

 intervals of two minutes, continued until the leaf closed. 



. . , Time in seconds which elapsed 



Number of 8'^ ^ between contact and 



., measurement .in, ^.-i i 



excitations. effect perceptible 



approach. 



1 to 7 00 



8 00 



9 00 



10 i 15-5 



11 i 10*8 



12 I 7-3 



13 1 '5-8 



14 U 5-0 



15 If 4-5 



16 2J 5-4 



17 3 4-5 



18 2 7-6 



19 ^ 3-8 



20 3| 3-7 



21 4J 3-3 



22 5J 4-0 



23 7 2-7 



■ 24 ^ 2-5 



25 8 l^ot observed. 



26 10 2-2 



27 At the 27th excitation the leaf closed. 



Prom this experiment, which was repeated several times and always 

 gave similar results, it was learnt : — (1) that the first half-dozen excita- 

 tions were absolutely without mechanical effect; (2) that the first 

 effectual excitation was followed by so slight a movement that if it had 

 not been enlarged by the lever it would have been imperceptible ; and (3) 

 that after this each successive approach of the lobes, in most cases, 

 exceeded its predecessor. The numbers recorded in the third column 

 relate to the time of interval between excitation and effect, and were 

 obtained by the following method. 



