MUSCLE 



221 



■^S?^^^^^^^^^^^^^^^^ 





B 



T.M. 



B 



. JIBS) 



k 



f- 





cfc. fe' 



s.c. 



Fig. 108.— a, Method of Recording Muscular Contraction. B, Key to parts 

 of Apparatus. M, Muscle attached to crank lever L. p.c. Primary 

 circuit, and, s.c, secondary circuit of an induction coil with short cir- 

 cuiting key, ¥, in secondary circuit. B, Galvanic cell, and, k, a mercury 

 key for closing and opening the primary circuit. T.M., a lever moved 

 by an electro-magnet placed in the primary circuit and marking the 

 moment of stimulation. In A, a tuning-fork beating 100 times per 

 second is shown recording its vibration on the drum. 



