14 



MOTION. 



It should frequently be moistened with a .7 per cent solu- 

 tion of common salt in water, culled Normal Saline Solution. 



Now take a sharp pair of scissors, and snip off the shortest 

 possible portion of the upper end of the sciatic nerve. If 

 the muscle is closely watched at the time when the nerve 

 is cut, it will be seen to thicken and shorten, and to lift the 

 weight. If the muscle be held between the thumb and finger 

 while the nerve is pinched (and the scissors are the surest 

 pinchers) it will be felt to harden. 



This experiment should be repeated, varying the weight, 

 until it is made very clear that when the nerve is stimulated 



Sciatic Nerve 



SHORTENED 



ELONGATED 



Fig, 3. Action of the Calf Muscle of the Frog, showing the Relations of the 

 Sciatic Nerve. 



the Muscle Shortens (which is the most important fact 

 the action), thickens, and grows harder. 



Structure of Muscle. Chipped beef shows well 

 structure of muscle. Looking at a piece closely we see ^Bet- 



fcout 

 ;ljRie 



