ELECTRO-PH YSIOLOG Y 



721 



response begins about y^^- second, and the change of form of 

 the muscle about y^y second after the stimulation. It is 

 believed that in a muscle directly excited the electrical change 

 begins in less than y^^ second, and the mechanical change in 

 i-tfu-o- second (Burdon Sanderson, Figs. 270-274). 



A. B. 



FIG. 270. ' SPIKE ' (DIPHASIC VARIATION) OF UNINJURED GASTROCNEMIUS 



(SANDERSON). 



A photographed on slow, B on fast-moving plate. 



FIG. 271. VARIATION OF 

 INJURED GASTROCNEMIUS 

 (SANDERSON). 



A ' spike ' followed by a 

 ' hump.' 



2. VARIATION OF INJURED 

 GASTROCNEMIUS (SANDERSON) 



The plate was moving ten times 

 faster than in Fig. 271. 



FiG. 273. VARIATION OF UNIN- 

 ED MUSCLE EXCITED EIGHTY- 

 FOUR TIMES A SECOND (SANDER- 

 SON). 



FIG. 274. CURVE OF AN INJURED MUSCLE EXCITED 

 SIXTY TIMES A SECOND (SANDERSON). 



