CHAPTER XVI 

 BONES 



304. Need of bones. Besides eating, breathing, and 

 sleeping, man's body does a great deal of heavy work that 

 would crush a soft body. Man also goes from place to 

 place and carries heavy weights that he could not carry 

 if he did not possess something on purpose to move his 

 body. Inside the body is a stiff and strong frame of bone, 

 which is moved by muscles. Bones form the frame of 

 nearly every part of the body, while the muscles which 

 cover them make the body plump and round. About one 

 seventh of the body is bone, while over one half is muscle. 

 In all there are over two hundred bones in the body. 



305. Shape of bones. Long bones extend down the 

 arms and legs, and slender bones form the fingers and toes. 

 Flat, curved plates of bone form the skull. Rounded 

 bones form the wrists and ankles, and rings of bone form 

 the backbone. Bones are of different shapes in order to 

 fit into the different parts of the body. 



Each long bone is a hollow shell like the frame of a 

 bicycle. This makes it strong and yet light. Its hollow 

 inside is filled with a soft fat called marrow. 



The ends of long bones are like a fine honeycomb 

 covered with a hard shell of firm bone. This makes them 

 light and yet able to resist the pressure of the body above. 



306. Strength of bone. Each bone is very hard, and 



