214 LIFE AND WORK OF SIR JAGADIS C. BOSE 



brought to sensory prominence. When the external blow, on 

 the other hand, is too violent we would block the pain- 

 causing impulse by rendering the nerve a non-conductor. 



Under narcotic the nerve becomes paralysed, and we can 

 thus by its use save ourselves from pain. But such heroic 

 measures are to be resorted to only in extreme cases, as when we 

 are under the surgeon's knife. In actual life we are confronted 

 with unpleasantness without notice. A telephone subscriber 

 has the evident advantage, for he can switch off the connection 

 when the message begins to be unpleasant. But it is not every- 

 one that has the courage of Mr. Herbert Spencer, who openly 

 resorted to his ear-plugs when his visitor became tedious. 



Bose then proceeds to consider the characteristics 

 of nervous impulse. Stimulus causes a molecular upset in 

 the excitable living tissue, and the propagation of nervous 

 impulse is a phenomenon of the transmission of molecular 

 disturbance from point to point. This molecular upset 

 and propagation of disturbance may be pictured simply 

 by means of a row of standing books. A certain intensity 

 of blow applied, say, to the book on the extreme right would 

 cause it to fall to the left, hitting its neighbour, and 

 making the other books topple over in rapid succession. 

 If the books have previously been tilted towards the left, a 

 disposition would have been given to them which would 

 bring about an upset under a feebler blow and accelerate 

 the speed of transmission of disturbance. A tilt in the 

 opposite direction would, on the other hand, be a pre- 

 disposition to retard or inhibit this. Thus, by means of a 

 directive force, we may induce a predisposition in the 

 system which would enhance or retard the transmitted 

 impulse. In a similar manner Bose imagined that opposite 

 reactions of a polar character might be discovered by 

 which molecular dispositions of opposite character could 

 be induced in a nerve so as to enhance or to retard the 

 conduction of nervous impulse. 



The possibility of such a control of nervous impulse 

 at will must be tested by experiment. Can opposite 

 molecular dispositions be induced in the nerve, in conse- 



