THE CHANGE IN FORM 349 



millimetre. Eaise the writing point of the lever 

 one millimetre by means of the after-loading 

 screw. Stimulate the muscle with a make in- 

 duction current of the same intensity as before. 

 Again turn the drum and raise the point of the 

 lever one millimetre, and stimulate the muscle 

 as before. Continue this until the after-loading 

 screw is raised so high that the muscle no longer 

 shortens sufficiently to raise the lever. 



Obviously in this experiment the weight is arti- 

 ficially supported during a progressively greater 

 portion of the contraction. It will be found that 

 the total shortening of the muscle loaded only 

 during the latter portion of the contraction is 

 as great as the shortening of a loaded muscle in 

 tetanus. 



THE ISOMETRIC METHOD 



Thus far we have observed the development 

 of energy in a muscle stretched by a small, un- 

 varying load. The principal part of the energy 

 set free in this isotonic process appears as the 

 mechanical energy of a visible change in form ; 

 a small part of the energy of the muscle is con- 

 verted into tension. Tick has pointed out that 

 if the muscle be made to pull against a strong 

 spring, the change in the length of the muscle 



