322 CHAP. XXIX. GEO-ELECTRIC RESPONSE OF THE SHOOT 



incapable of giving an accurate value of the latent period. 

 The electric method of investigation labours under no such 

 disadvantage : for, since the excitation is hereby detected 

 independently of movement, the incidence of stimulus is 

 followed by response without any undue delay. I will give 

 a record of the electric response of the quickly reacting 



Fig. 195. Geo-electric response of Anthurium. 

 period shorter than 5 seconds. 



Latent 



peduncle of Anthurium, when the angle of inclination was 

 increased from zero to 90°. The responsive movement of 

 the galvanometer spot of light was initiated in less than 

 5 seconds and the maximum deflection was reached in the 

 course of about 30 seconds. The angle was next reduced 

 to zero, and the deflection practically disappeared in the 

 further course of a minute and a half (fig. 195)- There 

 was a small ' excitation remainder ' : but with vigorous 

 specimens the recovery is completed in a short time. 



The latent period of the mechanical response of the 



