THE DEVELOPMENT OF THE JAW. 



187 



in fact constitutes almost the whole increase in vertical 

 dimensions down the passage from the child's to the adult's 

 form of the jaw. 



FIG. 81 ('). 



FIG. 82 ( 2 ). 



In the lower jaw we may take.it as proven that the 

 basal portion has little relation to the development of 

 the teeth, but that the alveolar, or upper portion is in 

 entire and absolute dependence upon them, a point to 



( J ) Lower jaw of an adult. 



( 2 ) Lower jaw of an aged person, the dotted lines indicating the outline 

 of the parts removed by absorption, as the jaw assumes the form charac- 

 teristic of advanced age. 



