ANATOMICAL STEUCTUEE OF THE SHEEP. 



breaking from any ordinary cause. The external surface of 

 every bone is covered by a dense, tough, inelastic membrane 

 called the periosteum, except where a tendon plays over the 

 bone, or where one bone articulates with another, in which places 

 will be found a layer of cartilage. 



The periosteum is firmly adherent to the bone, and is the 

 bed in which the blood vessels and nerves supplying the bone 



Skeleton of the Sheep. 



are distributed. It becomes very painful when inflamed, on 

 account of the pressure on the nerves, due to its inelasticity. 

 It is the protecting life membrane of the bone it covers; any 

 bone denuded of this covering will in all probability die, ex- 

 foliate and decay. 



The long bones of the limbs contain a hollow cavity 

 extending from one end of the bone to the other. This 

 cavity contains a substance called the marrow, which is a soft 



