188 



Professor Jagadis Ch under Bose 



[May 29, 



Mimosa failed to arrest the impulse. This result, at first sight, 

 appears most convincing, and has been universally accepted as a 

 disproof of the existence of nervous impulse in Mimosa. A little 

 reflection will, however, show that under the particular conditions of 

 the experiment the conducting tissue in the interior could not have 

 been affected bj the external application of the narcotic, the task 

 being, in fact, as difficult as narcotizing a nerve-trunk lying between 

 muscles by the application of chloroform on the skin outside. 



The question of nervous impulse in plants has thus to be attacked 

 anew, and I have employed for this purpose twelve different methods. 



Fig. 12. — Experimental Arrangement for Determina- 

 tion or Velocity of Transmission and its Varia- 

 tion. Record is first taken when stimulus is applied 

 near the pulvinus at B (latent period) and then at a 

 distant point on the leaf-stalk at A. Difierence of two 

 gives time for transmission from A to B. The band 

 of cloth C is for local application of warmth, cold, 

 ansesthetics, and poison. 



They all prove conclusively that the impulse in the plant is identical 

 in character with that in the animal. Of these I shall give a short 

 account of three different modes of investigation. It is obvious 

 that the transmitted impulse in Mimosa must be of an excitatory, or 

 nervous, character : 



(1) If excitation can be initiated and propagated without any 

 physical disturbance. The central fact in the mechanical theory is 

 the squeezing out of water for starting the hydraulic impulse : the 



