PLANT RESPONSE 



129 



clock-work. The excursion of the spot of light caused by 

 the responsive movement of the plant-organ, is followed 



FIG. 7. The Optical Pulse-Recorder. B, arm of optical lever attached 

 to moving leaflet ; L, ray of light, which after two reflections 

 from the two mirrors falls on the recorder ; C, clock-work, which 

 keeps twin-drum on which is wrapped the recording paper 

 revolving ; H, horizontal guide bar ; K, inkwell with projecting 

 sponge. 



by means of a sliding inkwell, from which projects the 

 ink-sponge. By this means, the tracing of the response- 

 curve and its various modifications under the action of 

 different influences can be demonstrated. In the figure 

 here reproduced the short arm of the optical lever is 

 attached to the pulsating leaflet of the Telegraph-plant. 



