178 



Dr. A. V. Hill. The Energy 



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The Energy Involved in the Electric Change in Muscle and Nerve. 



Bv A. V. Hill, F.R.S. 



(Received April 8, 1921.) 



Considerable electromotive forces are produced by the activity of excited 

 muscles or nerves — up to three or four hundredths of a volt — and it was 

 conceivable that an appreciable amount of energy might be involved in the 

 currents set up in the tissue by them. This paper contains an examination 

 of the question. 



In fig. 1 is shown a nerve fibre, on which rest electrodes (not shown) 

 connected to an electrometer or galvanometer. Along the outside of the 

 fibre is travelling, from right to left, a wave of negative potential, with 

 velocity a cm. per second, having at any point distant x cm. along the 

 nerve, and at time t seconds, a value y volts, as recorded on the electro- 

 meter, and shown (after the appropriate analysis) in the lower curve of the 

 ficure. We are not concerned here with the cause of this electromotive 

 change, nor with what happens inside the fibre, but only with the physical 

 results of it in an external circuit. 



In consequence of the differences of potential existing along the length of 

 the nerve, currents tend to flow, as shown by the full arrows and the strength 

 of the current flowing at any moment between two neighbouring points, is 



