FATIGUE OF MUSCLE. 



179 



(d.) The best plan is to fix a platinum style on the 

 spindle of the drum, and as it revolves it comes in contact 

 with another piece of platinum introduced into the primary 

 circuit, and fixed to the base of the drum-support, so that a 

 break shock is obtained each time the drum revolves. 



(e.) Observe how rapidly the height of the curves falls, 

 while their duration is longer. In nearly every case fatigue 

 curves from muscle show a "stair-case" character (Fig. 71), 

 the second curve being higher than the first one, and the 

 third than the second. 



2. Instead of recording on a moving surface, a stationary one 

 may be used (or a very slow-moving drum, 1 mm. per sec.), 

 either a drum or a flat glass surface, while the muscle may 

 be attached to a crank-myograph or to Pfliiger's myograph 

 <Fig. 72). 



Fig. 72. Pfliiger's Myograph. K, Clamp; M, muscle; W, weight in scale 

 pan; F, writing- style; P, counterpoise of lever ; S, S, supports. 



(a.) Arrange the experiment as before, but adjust the 

 muscle in a Pfliiger's myograph, the primary circuit being 

 still broken by a revolving drum. 



