THE PHENOMENON OF CONTRACTION. 



33 



preceding or following the development of the state of fatigue. Whenever 

 it occurs the effect is to hold the muscle in a state of maintained contraction or 

 tone, on which is superposed the series of quick contractions and relaxations 

 due to the separate stimuli. When the condition develops early in the func- 



tional activity of the muscle (Fig. 14) further activity usually causes it to dis- 

 appear, and the condition of the muscle as a mechanism for prompt shortening 

 and relaxation is improved. We have in this fact apparently an indication 

 of one way in which the " warming up" exercise before athletic contests may be 

 3 



