DENTINE 279 



cases, where the action of the secreted acid has been 

 in considerable advance of the invading micro-organisms. 

 An examination of the silver-stained developing tooth shows 

 that this appearance is due to structural conditions which 

 have been revealed by the action of the acid (fig. 176). 



As previously stated, the calcospherites seen at the 

 margins of human dentine appear clear and structureless, 

 but it was pointed out by Rainey, referring to the calcifica- 

 tion of the clear calcospherites in shell, that ' as the develop- 



FIG. 178. Calcoglobulin contours in forming dentine. 

 Uneiupted premolar. ( x 700.) 



ment progresses the globules lose their bright and structure- 

 less character and begin to present laminae and radiating 

 lines just as the artificial calculi do, the lines being more 

 distinct when the globules are suffering disintegration '. 

 Figs. 178 and 179 show that this is the case in the dentine. 

 The decalcified calcospherites are seen to have first coalesced 

 into larger bodies and then to have become laminated, 

 showing strongly-marked concentric striae. The dentine is 

 stained a deep brown by the Cajal process and is everywhere 

 traversed by these contours. The circular bodies are of 

 very various sizes, and the outermost striae composing the 



