THE CHANGE IN FORM 355 



is near the free end of the spring, contractions of the 

 abductor indicis muscle with voluntary and electrical 

 stimuli may be recorded. When the point of the 

 rod is placed near the cast-iron support of the spring, 

 the movements of the spring will be so much less that 

 almost none of the energy of the muscle will be con- 

 verted into mechanical motion. An isometric con- 

 traction will be recorded. 



Isometric Contraction. Place the point of the 

 adjustable rod in the hole nearest the cast-iron 

 support of the spring. The movement of the 

 spring is so much less at this point that almost 

 none of the energy of the muscle will be con- 

 verted into mechanical motion. Stimulate the 

 muscle as before with a maximal break induc- 

 tion current. Compare the isometric curve thus 

 recorded with the largely isotonic curve previ- 

 ously obtained. 



Artificial Tetanus. Eeplace the adjustable rod 

 in its former position (isotonic arrangement). 

 Stimulate the abductor with the tetanizing cur- 

 rent of the inductorium. Compare the curve 

 with the tetanus of frog muscle. 



Natural Tetanus. 1. Contract the abductor 

 by voluntary impulse. This also gives a tetanus 

 curve. When the natural tetanus is prolonged, 

 it frequently is marked by oscillations having a 

 periodicity of about ten per second. 



