616 Professor Jagadis Ghunder Bose [May 10, 



WEEKLY EVENING MEETING, 

 Friday, May 10, 1901. 



George Matthey, Esq., F.E.S., Vice-Pi-esident, 

 in tbo Chair. 



Professor Jagadis Chonder Bose, M.A. D.Sc, Professor of 

 Presidency College, Calcutta. 



The Response of Inorganic Matter to Mechanical and 

 Electrical Stimulus. 



When we pinch a living muscle, or send through it an electric 

 shock, certain changes take place. A responsive twitch is produced ; 

 tne muscle is changed in form, becoming shorter and broader ; the 

 particles of the living substance are strained under the stimulus. 

 The effect of the shock then disappears, and the muscle is seen to 

 relax into its usual form. 



This sudden change of form then, is one, but not 

 Mechanical the only, mode of response of a living substance to 

 Response. external stimulus. Under the stress the muscle is 



thrown into a state of distortion or strain. On 

 the cessation of stimulus it automatically recovers. As long as it 

 is alive, so long will it respond and recover, being ready again for 

 new response. This brief disturbance of a living poise, to be imme- 

 diately restored to equilibrium of itself, is quite unlike the rolling of 

 a stone downhill from a push. For the stone cannot regain its 

 original position, but the living tissue at once reasserts its first 

 stable poise on the cessation of stress. Thus a muscle, as long as 

 it is alive, remains ever-responsive. It is in intimate relation with 

 the forces by which it is surrounded, always responding to, and 

 recovering from, the multitudinous disturbances of its physical envi- 

 ronment. 



The living body is thus affected by external stimuli — mechanical 

 shock, sound, electrical stimulus, and the stimuli of heat and light — 

 which evoke in it corresponding responses. 



In the case of the contraction of muscle by mechanical or electric 

 shock, the effect is very quick, and the contraction and relaxation 

 take place in too short a time for detailed observation by ordinary 

 means. Physiologists, therefore, use a contrivance by which the 

 whole process may be recorded automatically. This consists of a 



