FATIGUE 39 



Instead of producing fatigue by a series of single induction shocks, 

 it may be produced by tetanising the muscle for a given period as 

 10 sees. ; or the drum may be allowed to revolve continuously, the 

 key in the secondary circuit being closed, the knock-down key 

 closed, and then the secondary circuit key opened at each revolu- 

 tion, so that each contraction of a series of break shocks is recorded. 



