1914] on Plant-Autographs and their Revelations 



17f> 



undergoes contraction, in consequence of which there is u fall of the 

 leaf. This sudden movement constitutes the mechanical response of 



Fig. 1. — Diagrammatic Representation of Plant-Recorder. 

 Responding leaf attached to one arm of lever V, at the 

 fulcrum of which is attached W, the writer. G, sliding 

 smoked glass plate for record. Recording plate is lifted 

 and allowed to drop. At a definite position during fall, R 

 makes momentary electric contact with R', giving rise to 

 instantaneous electric shock at A. Moment of application 

 of stimulus marked on recording plate by arrow a ; arrival 

 of excitation at B causes fall of leaf, which pulls the writer 

 to left describing h c. For determination of latent period, 

 stimulus is applied on the pulvinus at B. 



I the leaf to the impinging- stimulus, just as the contractile movement 

 ' of a muscle in similar circumstances forms its characteristic mechanical 



