BONES AND JOINTS 109 



EXERCISE 99 

 BONES AND JOINTS 



Apparatus and Materials. Pocket knife or needle mounted in a 

 small stick (dissecting needle), beef or mutton bone containing a joint 

 and sawed lengthwise, an old bone, chicken bones, a slender bone, 

 such as a "wishbone" or the rib of a lamb chop. 



a. Read 352, 353, and 354. Examine the bone in a piece 

 of uncooked "round" steak. Ask the butcher to get you a 

 fresh, long, beef (or mutton) bone that contains a joint end. 

 Have him saw the bone lengthwise, for an inch or two, through 

 the joint; then have him cut off one of the lengthwise pieces. 



Examine the sides and ends of the bone. What kind of 

 material covers the bone? Name it. Identify the marrow. 

 Can you find marrow of two different colors? At what part of 

 the bone is each kind? Do you find cartilaginous material at 

 the j oint? What are its uses? Describe the interior of the bone . 



b. Compare with the new bone an old bone that has been 

 dried thoroughly, or has lain out of doors for some time. 



c. Collect the bones of a fowl ("chicken") after the flesh 

 has been removed, and clean them thoroughly. Test some of 

 the bones to determine whether they are hard, or easy, to 

 break. Are they at all elastic? Chop, or saw, lengthwise into 

 the leg bone ("drumstick"); is it solid, or hollow? 



Find a hinge joint in the chicken; a ball-and-socket joint. 



d. Thoroughly clean and dry a slender bone, such as the 

 "wishbone" of a chicken or the rib of a lamb chop. Boil it 

 for a few minutes in water; then let it soak in hydrochloric 

 acid (1 volume of concentrated acid to 4 volumes of water) for 

 3 or 4 days. Finally rinse off the acid and examine the bone. 

 Is it hard now? What has the acid removed? 



e. Burn a small bone in a place where there is a good draught, 

 or on a bed of hot coals. Continue heating it until it is white. 



