786 



THE TEETH. 



Examined under the micro- 

 scope, dentine is seen to consist 

 of an immense number of very 

 fine tubes, imbedded closely 

 together in a hard intertubular 

 matrix, and having the appear- 

 ance of possessing distinct parie- 

 tes. These dental tubules open 

 at their inner ends into the pulp- 

 cavity, the wall of which pre- 

 sents very numerous minute ori- 

 fices over the whole of its inner 

 surface. Fruin thence they 

 pass in a radiated manner 



Fig. 545. SECTIONS OP DENTINE 

 (from Kolliker). 



A, highly magnified cross sections of 

 the tubuli of dentine. f-. a, from 

 a part in which the tubuli are very 

 closely set ; b, from a part where 

 they are widely set. 



B, longitudinal section of the root. 

 2fQ a, the dental tubes near the inner 

 surface of the dentine with few tubuli ; 

 6, subdivision of tubuli ; c, looped 

 disposition of the tubuli ; d, granular 

 layer consisting of small dental glo- 

 bules at the margin of the dentine ; 

 e, lacunas of the cement, one of them 

 connected by tubuli with those of the 

 dentine. 



through every part of the ivory 

 towards its periphery. In the 

 upper portion of the crown they 

 have a vertical direction ; but 

 towards the sides, and in the 

 neck and root, they become 

 gradually oblique, then hori- 

 zontal, and are finally even in- 

 clined downwards towards the 

 point of the fang. The course 

 of the tubules is not straight, 

 but each describes, in passing 

 from the central to the peri- 

 pheral part of the dentine, two 

 or three gentle curves' (primary 

 curvatures, Owen), and is be- 

 sides bent throughout its whole 

 length into numerous fine undu- 

 lations, which follow closely one 

 upon another ; these are the 

 secondary curvatures. The cur- 

 vatures of adjacent tubules so 



