114 



THE VITAL FUNCTIONS. 



in a growing state, the fangs are not yet added, but they are, 

 at one part, beginning to be formed. The same tooth, in its 



usual state, as worn by mastication, gives us a natural and 

 horizontal section of its interior structure, in which the plates 

 of white enamel are seen forming w r aved ridges. These con- 

 stitute, in the Asiatic Elephant, a series of narrow transverse 

 barids, (Fig. 283,) and in the African Elephant, a series of 

 lozenge-shaped lines, (Fig. 282,) having the ivory on their 

 interior, and the yellow crusta petrosa on their outer sides; 

 which latter substance also composes the whole circumfe- 

 rence of the section. 



4. Formation and Development of the Teeth. 



FEW processes in animal development are more remarka- 

 ble than those which are employed to form the teeth; for 

 they are, by no means, the same as those by which ordina- 

 ry bone is constructed; and being commenced at a very ear- 

 ly period, they afford a signal instance of Nature's provident 

 anticipation of the future necessities of the animal. The 

 teeth, being the hardest parts of the body, require a peculiar 



