Involved in the Electric Change in Muscle and Nerve. 181 



observed in a monophasic response), we can calculate this integral 

 numerically : suppose that its value is A : then the total heat becomes 



1 f . , _ A^ 

 4-18 Ea^* Jo 4-18 Ka2 



calories, 



or, per unit length, 



A 



calories. 



4-18 Ea2 



The value of K in this formula can be considerably decreased by immersing 

 the muscle or nerve in a conducting fluid. I am informed, however, by 

 Dr. E. D. Adrian that the potential difference of the action current as 

 measured by an electrometer also depends very much on the amount of fluid 

 adhering to the nerve, and that a large E.M.F. can be obtained only by using 

 a fairly dry nerve ; in fact, the external conducting fluid is acting as a short- 

 circuit and lowering the E.M.F. between any two points on the tissue. It is 

 probable therefore that no considerable increase in the production of heat 

 will be caused by lowering the resistance between two points on the nerve by 

 immersing it in a conducting fluid. "VVe will consider only the case of a 

 muscle or nerve in a reasonably dry condition. 



Let us apply the formulte deduced above to the case of the monophasic 

 electric change of the frog's sartorius, as determined by Keith Lucas* for 

 8° C. and 18° C. The data are as follows :— 



Sees. 



8° C. volts. 



18° 0. Tolts. 



Sees. 



8° 0. Tolts. 



18" C. volts. 



-0050 



-0013 





-0094 



-0325 



-0144 



-0050 



-0032 



-0011 



0-0100 



-0268 



-0107 



-0062 



-0089 



-0052 



-0106 



-0206 





-0069 



0-0187 



-0156 



\ 0-0112 



0140 



-0067 



-0075 



-0239 



-0213 



! -0125 



-0070 



-0054 



0-0081 



-0292 



-0251 



i 0-0150 





-0048 



-0087 



-0322 



-0217 









These numbers have been plotted in curves and the values of A calculated. 

 They are as follows : — 



As = 0-5, Ai8 = 0-35. 



The velocity of the wave may be taken to be roughly as follows in the two 

 cases : — 



As = 140 cm./sec, Ais = 220 cm./sec. 



These results are approximate only, as Keith Lucas does not give the exact 

 distance apart of his electrodes in the case where he recorded the diphasic 

 response. He states, however, that they were " as far apart as possible," and 

 from his figure their distance cannot have been far from 2 cm. The time 

 * ' Journal of Physiol.,' vol. 39, p. 220 (1909). 



