THE DEVELOPMENT OF THE TEETH. 



153 



received a partial impregnation with lime salt at its peri- 

 phery, and so being rigid, is unable to contract with the rest 

 of the cell. These enlarged, everted ends, often show a very 



FIG. 71 



sharp contour, their trumpet-like mouths tending to confirm 

 the statement of Waldeyer that the protoplasm of the cell 

 is not covered in by membrane at its ends. The impregna- 

 tion with calcareous salts commences at the free end of the 



FIG. 72 ( 2 ). 



enamel cell, and at the periphery before the central portion, 

 and it is to this fact that the existence of " Tomes' pro- 

 cesses " is due, for when the enamel cell is dragged away 

 from the formed enamel prism, it separates across the line 

 of calcification ; and thus the axial part of the cell, when 

 torn away, projects out further than its periphery, in con- 



( 1 ) Enamel cells with Tomes' processes. 



( 2 ) Enamel cells ; the two on the right have been shrunk by immersion 

 in glycerine, and present the open trumpet-shaped ends described in the 

 text. 



