78 



Chapter VI 



deflection of the live muscle continually diverged from the control 

 curve due to electrical warming for a short period. The only possible 

 explanation of this is that heat is being produced by the muscle in 

 O. 2 for long periods after the contraction is over. For examples of 

 this see Figs. 41 and 42. The fall of the deflection is due to heat-loss 

 and, where there is no delayed heat-production, is a simple ex- 

 ponential curve. From the control curve of electrical warming it is 

 possible to calculate the coefficient of heat-loss in the case of any 

 particular thermopile used, and from this to ascertain, in the case of 

 the live muscle in 2 , the true curve of heat-production. 



160 



SO 3C be SV 6c y c fc 



FIG. 41. Curves of galvanometer deflection for live muscle stimulated, and for dead 

 warmed (control). Also calculated curve of true heat-production of live muscle, 

 i.e. curve corrected for heat-loss. 



It was found that approximately as much more heat is produced 

 in the 4 or 5 minutes following a single shock in O 2 as was produced 

 in the first few moments after excitation occurred. There is there- 

 fore, but only in the presence of 2 , a very large recovery heat- 

 production lasting for some minutes after the contraction is over, 

 which recovery heat-production one can scarce but associate with 

 the oxidative removal of fatigue products (lactic acid, Fletcher and 

 Hopkins* 12 '). 



It was found moreover that any process, as e.g. a previous tetanus, 

 which uses up the O 2 existing already in the muscle delays or abolishes 

 the recovery heat-production. Hill concluded that oxygen is used, 



