98 ELEMENTAEY PHYSIOLOGY. [iX. 



11. Load the muscle with 50 grammes, allowing the 

 lever to write on the stationary cyliader. Note 

 the elasticity of the muscle. The weight when 

 applied stretches the muscle to a certain extent, 

 but when raised so as not to drag on the muscle, 

 the latter returns, at once to almost, and even- 

 tually to quite, its former length. Stimulate 

 with an interrupted current (coil say at 20). 

 Note the amount of contraction. Repeat this 

 with 100, and then with 200 grammes, using in 

 each case the same strength of current for the 

 same time, moving the cylinder with the hand 

 so as to expose a fresh black surface for each 

 observation. 



Observe that with medium weights the work 



done (the product of the weight into the height) 



is greater than with very light or very heavy 



weights. 



Observe also that the muscle gradually becomes 



exhausted, i.e. the contractions caused by the 



same stimulus gradually become less and less. 



12. Probably the preparation will be nearly exhaust- 

 ed; take as in § 7 a tracing of a single muscular 

 contraction, and note the difference in the form 

 of the curve; the rise is less rapid, the fall 

 more gradual, the muscle may take some time 

 to regain its original length. 



13. Reaction of Muscle. 



a. Remove the muscle from the moist chamber, 

 place it on a clean glass slide, and apply 

 the electrodes, connected with the induction 



