11 



treatment is all that is possible in the present state of oar 

 knowledge ; but deduction from results of experimental 

 investigation "still remains the ideal of physiology, and only 

 when this ideal has been attained, shall we be able to 

 obtain a comprehensive view of the interacting factors at 

 work in the living organism." 



In my previous work on " Plant Response " (1306) I 

 described detailed investigations on irritability of plants 

 which I carried out with highly sensitive recorders. The 

 plant was thus made to tell its own story by means of 

 its self-made records. The results showed that there is 

 no specific difference in physiological reaction of different 

 organs to justify the assumption of positive and negative 

 irritabilities. A generalisation was obtained which gave a 

 complete explanation of diverse movements in plants. 

 The results were fully confirmed by an independent method 

 of inquiry, namely that of electric response, which I have 

 been able to elaborate ao as to become a very important 

 means of research. 



The investigations described in the present volume 

 not only support the conclusions reached in my earlier 

 works, but have led to important additions. 'It is evident 

 that the range of our investigation is limited only by 

 our power of recording the rate of plant-movement, 

 that is to say, in the measurement of length and time. 

 In these respects the instruments that I have been able 

 to devise have surpassed my sanguine expectations. The 

 Resonant Recorder traces time-intervals as short as a 



