Fio. 69 



12, 



II 



(!) TRANSVERSE SECTION OF THE LOWER JAW AND DEVELOPING BACK TOOTH OK A LAMB, 

 copied from Waldeyer (Henle's Zeitschrift f. Rat. Med. 1865). In its outlines the figure is 

 faithful to nature ; it is so far diagrammatic that more of structure than could be seen with the 

 magnifying power employed is introduced. 



1. Dentine germ, with its border of pdontoblasts. 2. Formed dentine. 3. Formed enamel. 

 4. Points where the inner epithelium and the outer epithelium of the enamel become 

 continuous. 5. Enamel cells or internal epithelium, (i. External epithelium of enamel 

 organ. 7. Stellate reticulum of enamel organ. 8. Papillary projections into the enamel 

 organ. 9. Connective tissue around the sac, becoming continuous above with that of the 

 gum (9ft); this constitutes what is called the looth sac. 10. Vessels and nerves of the 

 jaw. 11. Bone of lower jaw. 12. Periosteum of the jaw. 13. Heap of epithelium over 

 the young tooth. 14, External skin with its epidermis. 15. Muscular bundles from floor 

 of mouth, 



[To face p, 143. 



