THE RESONANT RECORDER 



21 



obtaining response of Mimosa is shown in the accompanying 

 illustration (fig. 4). 



Having thus given an account, in some detail, of the 

 practical working of the Resonant Recorder, it will now 

 be well to show a pair of curves which demonstrate, in 

 a marked manner, the advantage of intermittent over 

 continuous contact in the making of these records (fig. 5). 

 These represent two successive experiments on the same 

 leaf, under identical stimulation of an electrical shock. 

 The recording-plate was 

 here moving at a mode- 

 rately high speed. The 

 lower record was taken 

 with continuous con- 

 tact, and the upper 

 with the same recorder 

 but in a state of vibra- 

 tion, giving intermittent 

 contact. The vibration- 

 frequency was 10 times 

 per second. Stimulus 

 was applied at the point 

 marked by the vertical 

 line. A comparison of 

 the two records will 

 show that owing to the 

 relative loss of freedom, 

 due to friction, in the 



continuous contact, the latent period, or the interval 

 between stimulus and initiation of response, is prolonged 

 and the amplitude of the response itself reduced. In the 

 case of the intermittent contact, on the other hand, we see 

 that besides the freedom from this particular error we have 

 the further advantage that the record itself contains its 

 own time-marks, the successive dots being at intervals of 

 one-tenth of a second. 



We have next to consider the practicability of devising, 



Fig. 5. — Advantage of intermittent over 

 continuous contact in obtaining re- 

 cords. 



