80 



THE HOUSE I LIVE IN. 



When the soft pieces of jelly which form 

 the teeth become lone, the process is as fol- 

 lows : First, a hard speck commences in the 

 centre of a tooth, and this gradually grows 

 larger till all the jelly is gone, and its place is 

 taken up by bone. 



The teeth, however, consist of something 

 else besides solid bone. If they did not, they 

 would very soon wear out. Do you think a 

 piece of common bone, put in place of a tooth, 

 would last us to chew with half a century or 

 more ? By no means. " But what then ? " 

 you will say. T will tell you. 



