22 RESEARCHES ON IRRITABILITY OF PLANTS 



for the excitation of the plant tissue, perfect methods of 

 stimulation, the intensity of which can either be maintained 

 constant or varied in a perfectly known manner. We 

 have moreover to render the successive stimulations, and 

 consequent scripts of the plant, a perfectly automatic 

 process ; so that the experimenter may be comparatively 

 relieved of personal participation in the securing of the 

 records. This will have the incomparable advantage of 

 having no element of personal error in the results so 

 obtained. The question of the effects of the various forms 

 of stimulus will be dealt with in the next chapter. 



Summary 



In the response-records of plants, errors are introduced 

 on account of friction of the writing-point against the 

 recording-surface. 



These errors are eliminated by the method of intermittent 

 instead of continuous contact for the record. By employ- 

 ing the principle of resonance, the writer is made to vibrate 

 to and fro at a known and definite rate. The record consists 

 of series of dots giving definite time-intervals. The record 

 is thus its own chronogram. 



