82 EXPERIMENTAL PHYSIOLOGY 



L. — Composition of Bone (Optional). 



Apparatus, — ^Two clean ribs, a soup bone split in two, 20% 

 hydrochloric acid, bottle big enough to hold rib, evaporating dish, 

 food-testing materials, Bunsen burner. 



Directions,— A. Place one of the ribs in the bottle and 

 fill the bottle with the 20% hydrochloric acid. Let it stand 

 for a few days. At the end of that time examine it. Has it 

 changed in shape? Take it out of the bottle and bend it. 

 What power has it lost? What substance is left? Hold a 

 little of it in the flame. Does it burn? Pour a little of the 

 acid from the bottle into the evaporating dish and evaporate 

 to dryness. What kind of substance is left? What material 

 did the acid dissolve out of the bone? 



B. Burn the other rib. What is the shape of the part that 

 is left? Is it flexible? Put some of it in the acid. Does it 

 dissolve? Name the two main constituents of bone. 



C, Cover the split soup bone with water and gradually 

 bring to a boil. Strain off the liquid and let it cool. What 

 do you find floating on the surface? What forms as it cools? 

 What is the character of this substance? Test for foods. 



LI. — Structure of a Joint. 



Apparatus. — Fresh leg joint of lamb or veal, scalpel. 



Directions. — ^Examine the tissue that binds the two 

 bones together. What is the character* of these bands, or 

 ligaments? Are they flexible? How do they control the 

 direction of movement of the bones? Cut off the ligaments 

 with a scalpel. Note the hquid found within. What does 

 it look like? (It is a lubricant called synovial fluid). 



