PREFACE ix 



of recording time-intervals as short as a thousandth part of 

 a second. A brief account of this is given in my paper 

 " On an Automatic Method for the Investigation of the 

 Velocity of Transmission of Excitation in Mimosa," read 

 before the Royal Society. It will be recognised immediately 

 in how many directions our power of inquiry has become 

 extended by the elaboration of these new methods and 

 the invention of several types of instrumental appliances 

 described in this work. ' 



In presenting the results of these investigations, it will 

 be noted that the plant has been made to tell its own story, 

 by means of its self-made records. Each experiment has 

 been repeated at least a dozen times, in many cases as often 

 as a hundred times. The results may therefore be accepted 

 as fully attested. The establishment of the unity of re- 

 sponsive reactions in the plant and animal, which is the 

 subject of this work, will be found highly significant, since it 

 is only by the study of the simpler phenomena of irritability 

 in the vegetal organisms that we can ever expect to elucidate 

 the more complex physiological reactions in the animal 

 tissues. 



I take this opportunity to thank my research assistants, 

 Messrs. Guruprasanna Das, L.M.S., and Surendra Chandra 

 Das, M.A., for the very efficient help rendered by them in 

 these researches. 



J. C. BOSE, 



Presidency College, Calcutta, 

 October 1912. 



