ENAMEL 91 



The tubes from the outside have very widely open orifices 

 and are stained deeply in broad vertical stripes within the 

 enamel ; these broad bands pass about half-way across 

 and then become fused in a deeply stained area which 

 extends horizontally across the enamel, being sharply 

 limited at the lower margin by the band of calcified prismatic 

 material previously described. If a tooth is examined 

 which is a little farther advanced towards eruption, the 

 stained horizontal band is seen to be broken up, only a few 



A k 



l d 



FIG. 45. As fig. 44, more highly magnified, t. Stained channels ; 6. hori- 

 zontal stained band; d. dentine; e. enamel prisms. (x!30.) 



patches of stained material being seen in its former position, 

 but many of the entering stained spaces are still very wide 

 and show laterally expanded areas. All stages of this 

 gradual contraction of the stained area are to be seen in 

 the molar teeth in different stages of development, to the 

 completed enamel of the tooth in wear. 



From these appearances it seems impossible to avoid 

 the conclusion that these tubes have a calcifying function, 

 conveying the lime salts to the organic foundation substance 

 of the enamel previously laid down. In no instance could 

 this stained horizontal band be seen to pass beyond the 



