CH. x.] MTOGRAPHS. 121 



shock is sent into the muscle-nerve preparation by the pendulum 

 in its swing opening a key in the primary circuit. This is shown 

 in an enlarged scale in BC (fig. 143). 



Fig. 143. Simple form of pendulum myograph and accessory parts. A, pivot upon which 

 pendulum swings ; S, catch on lower end of myograph opening the key, C, in its 

 swing; D, a spnng-catch which retains myograph, as indicated by dotted lines, and 

 on pressing down the handle of which the pendulum swings along the arc to D on the 

 left of figure, and is caught by its spring. 



fig. 144. Moist Chamber. 



