THE MUSCLES. 



551 



evolution of energy in them stimulates the neighboring fibers and 

 the contraction passes along the muscle. 



<u 



o> 



to 





 ' 



a 



&< 



t 



ff 



The velocity of a contraction-wave in muscle can be measured ; 

 the frog it is from three to four meters per second; in man, about 

 forty feet per second. 



