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extent and measure the space through which the hand has 

 been lifted. 



From the elbow joint measure the length of the forearm 

 and hand to the finger tips, and also to the insertion of the 

 biceps. Make a diagram, and from these data, and from your 

 knowledge of the mechanism of levers, calculate the extent 

 to which the muscle has shortened. 



Extent of contraction 



length of lever from fulcrum to power 

 length of lever from fulcrum to point 



x height of lift of hand. 



B. Force of Contraction. 



Lift a weight of 2 kilograms in the hand, as in the previous 

 experiment, and calculate what weight directly applied to the 

 muscle this represents. 



length of lever from fulcrum to weight 



= , x weight lifted. 



length of lever from fulcrum to power 



This is a measure of the force of the particular contraction. 



Dynamometer. Study the dynamometer provided, and 

 determine the force of contraction of the flexors of each 



hand. 

 i 



C. Work Done. 



From the extent of shortening of the muscle, and from 

 the weight lifted, calculate the work done by the biceps 

 muscle. 



Work done = weight lifted x extent of contraction. 



D. What is the Course of Contraction of a Muscle ? 



METHOD. Make a frog's gastrocnemius record its change 

 upon a moving surface. 



A. Apparatus. 



(1) Prepare an Induction Coil for single induction shocks, 

 putting the Drum, covered with smoked paper, in the 



