182 



Dr. A. V. Hill. The Energy 



relations of the diphasic response recorded by him then give the above 

 velocities. 



The resistance to an alternating current of a frog's sartorius muscle, after 

 death, between electrodes placed directly upon it, is given by the following 

 hitherto unpublished experiments, made by myself in 1913, at about 12° C, 

 by the method described in a previous paper.* 



(1) 

 (2) 

 (3) 



(4) 

 (5) 

 (6) 

 (7) 



No. of experiment 



Distance between electrodes, centimetres ... 

 Mass of muscle between electrodes, grammes 



Resistance between electrodes, ohms 



Resistance per centimetre, ohms 



Mass per centimetre, grammes 



(5)x(6) 



1 



2 



3 



4 



5 



3-0 



2-85 



3-2 



3-7 



3-2 



0-183 



0-147 



0-205 



0-241 



0-207 



13540 



14860 



12300 



15910 



12800 



4510 



5220 



3850 



4300 



4000 



-061 



-0515 



-064 



065 



0-065 



275 



270 



247 



280 



259 



The muscles being of different sizes, the conductivity should be proportional 

 to the mass per centimetre, or, in other words, the resistance per centimetre 

 multiplied by the mass per centimetre should be constant. That this is so is 

 shown by the last row where this quantity is tabulated, We may assume 

 therefore that a muscle 1 cm. long, weighing 1 grm., has a resistance of about 

 260 ohms at 12° C. Substituting this value with those preceding in the 

 expression for the heat per unit length of muscle, viz., H = A /i'lS Ea^, we find 

 0-5 



Hi8 = 



4-18x 260x 1402 

 0-35 



= 23'4 X 10 ^ calories per gramme, 

 = 6'6 X 10"^ calories per gramme. 



4-18x260x2202 



The quantity of heat liberated in a muscle twitch is of the order of 3 x 10~^ 

 calories per gramme, a quantity more than one hundred thousand times as great 

 as the larger of the quantities calculated ahove. The amount of energy 

 associated with the electric change in a muscle is negligible therefore when 

 compared with that liberated in the subsequent contraction. 



The same formulae may be applied to the case of a nerve. Dr. E. D. Adrian 

 has kindly provided me with a record of a monophasic response of a frog's 

 sciatic nerve at 6'2° C, which is the curve shown in the lower half of fig. 1. 

 Here the calculated value of A is 0"38 (compare this with the value 0"5 given 

 above for the sartorius muscle at 8° C), and the value of a was about 

 10 metres, i.e., 1000 cm. per second. Assuming that the specific electrical 

 resistance of nerve is the same as that of muscle, an assumption which can 

 cause no serious error, the value of the heat production at 6'2° C, per gramme 

 of nerve, caused by the passage of a single electric change becomes, 



0-38 



H6 = 



3'o X 10 ^° calories. 



4-18 X 260 x 10002 

 * A. V. Hill, ' Journal of Physiol.,' vol. 46, p. 457 (1913). 



