164 A MANUAL OF DENTAL ANATOMY. 



live pulp takes place, but the additions to the base of the 

 tooth are of constant, or ever-increasing dimensions, as is 

 the case in some tusks, which are of conical form. 



It is said that the number of roots which would have been 

 developed at the base of a particular dentine organ may be 

 inferred from the vessels, i. e., that in a single rooted tooth 

 the vessels would, even at an early period, form a single 

 fasciculus, in a double rooted one similarly they would be 

 arranged in two bundles, so that the ultimate formative 

 activity will be exercised around one, two, or three centres 

 of nutrition. I am not however able, from my own ob- 

 servations, to thrown any light upon this matter. 



THE CALCIFICATION OF VASO-DENTINE. 



During the conversion of the membrana eboris into 

 ordinary hard unvascular dentine the vessels of the formative 

 pulp recede, so that, whilst at all stages a capillary plexus 

 is to be found just below the odontoblast layer, no vessels 

 are to be found amongst the cells which constitute it. 



Nevertheless a moment's reflection will show that (except 

 in the earliest stages, before any dentine is formed) the 

 plexus must at a prior time have occupied the place now 

 taken possession of by the inward marching odontoblasts and 

 dentine. 



But in the calcification of a formative pulp into vaso- 

 dentine this recession of its vessels before the advancing 

 border of calcification does not take place ; the whole vascular 

 network of the papilla remains and continues to carry blood 

 circulating through it, even after calcification has crept up 

 to and around it. 



So that if we imagine a vascular papilla to have its 

 stroma suddenly petrified whilst its circulation went on all 

 the same, we should have something like a vaso-dentine. 



Just as in hard dentine, the odontoblast layer is distinctly 



