THE FRAMEWORK OF THE BODY 19 



the animal substance insures toughness and elasticity, so that 

 by their union we are able to withstand greater shocks and 

 heavier falls than would be possible with either alone. In 

 youth, the period of greatest activity, the animal portion is 

 in excess j a bone then does not break so readily, but, when 

 broken, unites with great rapidity and strength. On the other 

 hand, the bones of old persons are more easily broken, and in 

 some cases fail to unite. The mineral matter being then in 

 excess, indicates that the period of active exertion is drawing 

 to a close. (Read Note 3.) 



5. The Structure of the Bones. If we examine one of the 

 long bones, which has been sawed through lengthwise, we 



PIG. 1. SECTION OP BONE. A, Longitudinal. B, Trans- 

 verse Section of Bone 



observe that it is admirably fashioned for affording lightness 

 as well as strength (Fig. 1). Its exterior is hard and resisting, 

 but it is porous at the broad extremities, while through the 



water), when the bone will become perfectly soft and pliable. The speci- 

 men may be preserved in alcohol indefinitely. 



3. Some Properties of Bone. "The power of bone to resist decay is 

 remarkable. Fossil bones deposited in the ground long before the ap- 

 pearance of man upon the earth have been found by Cuvier, exhibiting a 

 considerable portion of cartilage. The jaw of the Cambridge Mastodon 

 contained over forty per cent, of animal matter enough to make a 

 good glue and others about the same. From this we see that a nutri- 

 tious soup might be made from the bones of animals that lived before the 

 creation of man. The teeth resemble bone in their structure, but resist 

 decay longer ; they are brought up by deep-sea dredging, when all other 

 parts of the animal have wasted away. The bones differ at different ages, 



5. In what respect admirably fashioned ? Its formation ? Microscopic examination ? 

 The inference ? " Line of beauty ? " 



