88 MICROSCOPIC ANATOMY OF THE TEETH 



This is clearly shown in ground preparations, the red- 

 stained tubes being sharply relieved against the unstained 

 yellowish enamel. In his work on dental histology Mr. Hope- 

 well Smith says 'the tubes are found in the longitudinal 

 axes of the enamel rods ' ; that this is not the case is very 

 evident in the preparations here referred to the tubular 

 system is completely independent of the enamel rods as 

 shown both in the completed tissue and in teeth in the 

 course of development. This band near the dentine appears 



P 



FIG. 42. Sargus ovis. Incisor tooth (stained with alcoholic fuchsin by 

 capillary attraction). Within the pulp (p) are seen the vascular channels 

 shown in fig. 160 (here cut across). ( x 50.) 



to be made up of prisms very intricately arranged, and it 

 is quite impossible to trace the course of individual prisms. 

 This pattern can be seen in the abundant organic matrix 

 of the enamel which is laid down in the early stages of its 

 development before any calcification has commenced. In 

 many preparations in which the enamel cap was quite soft 

 and easily cut with a knife the same pattern of twisted and 

 spirally arranged prisms was seen, and such preparations 

 took stains deeply. In the fully-formed tooth a clear area is 

 always to be seen between this layer and the dentine (fig. 43). 

 The first preparations of Sargus enamel examined by the 



