DEVELOPMENT OF THE ENAMEL 187 



marked differences of arrangement in the different species 

 examined. 



As in Sargus, the enamel organ is penetrated by a regular 

 system of vascular tubes which are mostly arranged in 

 a radiating manner more or less at right angles to the surface 

 (fig. 104). At the sides of the enamel organ, however, many 

 of these tubes are arranged more or less horizontally. As 

 shown in fig. 105, the blood-vessels are enclosed in a very 

 distinct sheath, and these can be teased out and separated 

 from the surrounding tissue. The separation of the masses 



FIG. 104. Tooth germ of Tautoga (Labridae). 6. The vascular tubes 

 in the enamel organ ; e. points to detached uncalcified enamel ; d. dentine 

 showing section of the flange on which the enamel rests ; p. pulp. ( X 50.) 



of blood corpuscles would appear to be partially due to 

 clotting, and also to the fact that the sheath appears to be 

 continued in a transverse direction across the enamel organ. 

 When a true vertical section is procured it is seen that the 

 vascular tubes are surrounded by cellular elements arranged 

 exactly like a simple tubular gland (figs. 106 and 107), and that 

 within the centres of these gland-like structures channels are 

 visible filled with granules, these channels becoming approxi- 

 mated below and passing into a similar delicate stroma to 

 that seen inSargus intervening between the enamel organ and 

 the forming enamel. This apparatus would apparently serve 

 the same purpose as the somewhat identical arrangement 

 in the enamel organ of Sargus, conveying the lime salts 

 elaborated in these gland-like structures from the blood- 



