THE FRAMEWORK OF THE BODY 57 



minute structure of cartilage, cut very thin sections with a razor from 

 the articular surface of a fresh bone of a young animal, mount in 

 normal salt solution, and examine with the compound microscope. 



12. Structure of Bone. Procure, at a meat market, a leg bone of 

 some animal and compare it in appearance with a similar bone that 

 has been exposed to the weather for months. Observe the pink color 

 of the fresh bone, and the fibrous periosteum that covers it. Saw 

 the two bones open lengthwise and observe the marrow cavity in each. 

 Notice the compact shaft of each, and the cartilage on the articular 

 surface of the fresh bone. 



13. Minute Structure of Bone. Mounted sections of bone may be 

 procured of dealers in microscopical supplies, or the teacher may pre- 

 pare them by sawing thin pieces from the shaft of a dry weathered 

 bone and then filing them down till they are extremely thin. They 

 may be mounted in water on a slide and examined with the micro- 

 scope. But a better way is to dry the sections thoroughly, after care- 

 fully washing them in alcohol, and then to mount them in Canada 

 balsam that has been evaporated until it solidifies on cooling. The 

 sections should be quickly placed in the hot balsam upon a clean slide, 

 covered with a cover glass, and cooled to harden the balsam. 



14. Composition of Bone. Two pieces of the same fresh bone or two 

 similar fresh bones should be obtained. Burn one piece in a fire for 

 several hours till it turns completely white. All the animal matter 

 has been removed. Place the other piece of bone in weak muriatic 

 acid (10-15 per cent strength) for several days to decalcify. It becomes 

 soft, owing to the removal of the mineral matter. Observe the brittle- 

 ness of the burned bone, and the toughness and flexibility of the other 

 piece. Place the burned bone in the muriatic acid, and burn the piece 

 of decalcified bone. What is left? 



15. Joints. The various kinds of joints can be demonstrated on a 

 skeleton. The actual movements that occur at those joints should be 

 performed by the student in corresponding joints of his own body. 



16. Dissection of a Joint. Procure a leg joint of a sheep and show 

 the possible movements of the bones that form the joints. Observe the 

 tendinous attachments of muscles, also the ligaments that hold the 

 bones together. Cut through the ligaments and open the joint cavity. 

 Notice the synovial fluid, and the cartilage on the articular surfaces 

 of the bones. 



