THE DENTAL TISSUES. 77 



pulp cavity, is formed. But in the lower part of the tooth 

 slight longitudinal furrows appear on the surface, which, on 

 transverse section, are seen to correspond to dippings in of 

 the dentine ; and the dentine is, as it were, in folds. The 



FIG. 37 



pulp on section might be compared to a paddle-wheel, the 

 floats of which correspond to the thin flat radiating pro- 

 cesses of pulp ; but as yet the central pulp chamber is 

 unaltered. A little lower down, as represented in the 

 accompanying figure, there is no longer a central simple 

 pulp chamber; the inflections round the periphery have 

 become relatively much deeper, and the centre of the tooth 

 is occupied by a tissue irregular, but not otherwise unlike 

 the dentine of Myliobates ; that is to say, there are a 

 number of columns of pulp, each of which forms the axis 

 whence a system of dental tubes radiate. 



The outrunning plates of dental pulp, which on section 

 radiate out like the spokes of a wheel, do not always remain 

 single ; they may divide simply into two branches, as may 

 be seen in the section across the base of the tooth of 



( a ) Transverse section across the crown of the tooth of Varanus, near to 

 its base. The central pulp cavity is produced out into processes, and it 

 might be said the dentine is arranged in plates with some little regularity 

 round its periphery. 



