366 THE OUTGO OF ENERGY 



with the muscle at rest; (2) with the muscle 

 tetanized. These abscissae record the length of 

 the practically unloaded muscle in the resting 

 ;ind the active states. Place 10 grams in the 

 scale-pan and again record the length of the 

 muscle (1) at rest ; (2) tetanized. Make similar 

 records for each 10 grains up to 100. 



It will be found that the extension curve falls 

 more rapidly in the active than in the rest- 

 ing muscle ; the extensibility is increased in 

 tetanus. 



FATIGUE 



Skeletal Muscle of Prog. 1. Let a gastro- 

 cnemius muscle loaded with 10 grams write its 

 contractions on a very slowly moving drum. 

 Connect the secondary coil with the binding 

 posts on the muscle clamp and the muscle lever. 

 Stimulate the muscle once in two seconds with a 

 maximal induction current, using make and break 

 currents alternately. The correct interval may be 

 obtained by listening to the beat of a metronome. 

 Continue to record the contractions until- the 

 muscle will no longer shorten when stimulated 

 (exhaustion). 



State the characteristic features of the fatigue 

 curve. 



2. With a fresh muscle repeat the stimulation 



