DENTAL TISSUES. 



3G5 



wards, from its circumference, a series of vertical plates, which 

 divide into two once or twice before they terminate at the 

 periphery of the tooth. 



Each of these diverging and dichotomising plates gives off 

 throughout its course smaller processes, which stand at right 



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Section of tooth of Dugong ; a, natural size; b, magnified ; d, dentine ; c, cement, v. 



angles, or nearly so, to the main plate ; they are generally oppo- 

 site, but sometimes alternate ; many of the secondary plates or 

 processes, which are given off near the centre of the tooth, also 

 divide into two before they terminate ; and their contour is seen, 

 in the transverse section, to partake of all the undulations of the 

 folds of cement which invest and divide the dentinal plates and 

 processes from each other. 



The dental pulp-cavity is reduced to a mere line about the 

 upper third of the tooth, but throughout its whole extent fissures 

 radiate from it, corresponding in number with the radiating plates 

 of dentine. Each fissure is continued along the middle of each 

 plate, dividing where this divides, and extending along the middle 

 of each bifurcation and process to within a short distance of the 

 line of cement. The pulp-fissure commonly dilates into a canal 



