150 LIFE AND WORK OF SIR JAGADIS C. BOSE 



a pin, the normal rate was at once depressed to a fourth, and it 

 took about two hours for the plant to recover from the effect 

 of the pin-prick. A slash made with a knife was found to 

 arrest the growth, the inhibition persisting for a very long 

 period. Severe shock caused by a wound thus retards the 

 growth in normal healthy specimens. 



The reactions in exceptional cases are highly interesting. 

 Certain plants, for reasons at present obscure, remain} stunted 



FIG. 1 5. Depressing effect of a passing cloud on the response of Mimosa. 



in growth, the branches and flea ves presenting an unhealthy 

 look. Lopping off the offending limb, curiously enough, is found 

 good for the plant. The stimulus of severe shock renews the 

 growth that had remained arrested. 



Another series of investigations was carried out with the 

 leaflet of the Telegraph plant, which pulsates up and down, 

 like the movement of a semaphore. When the leaflet is cut 

 from the parent plant, and the cut end placed in water, the 

 pulsation is found to be arrested by the shock of operation. 

 After a time the pulse-throb is slowly renewed, and maintained 

 for nearly 24 hours. But death had found an unguarded 

 spot at the wound ; and its march, though slow, is sure. The 

 death-change thus reaches the throbbing tissue, which becomes 



