164 



E. Nunn. On the Development of [June 15, 



fclie cuticula lias frequently been considered as " the newly-formed 

 layer of enamel " and also as the basement membrane. 



2. The basement membrane may be demonstrated upon the surface 

 of the tooth-papilla and upon the tooth in all stages of development. 

 It becomes calcined with the other hard tissue of the tooth and cannot 

 be separated by acid. 



3. The enamel, like the dentine, owes its origin to the odontoblasts, 

 the processes of which, in an early stage, may be traced quite up to its 

 outer edge. 



EXPLANATION OF FIGrTTRES. 



The same letters have been employed to mark corresponding structures in the 

 whole series of figures. 



The figures were drawn by the aid of the camera. 

 b. m. Basement membrane. 



c. Cuticula dentis. 



cal. Limit of calcification. 

 el. Cleft formed by pressure of coyerslip, dissecting needle, &c. 



d. Dentine. 

 der. Derma. 



di. Disks. 



e. Enamel. 



e. c. Enamel cells. 

 e. m. Enamel membrane. 



ep. Epithelium. 

 e. I. External layer of the enamel organs. 

 e. o. Enamel organ. 



f. Dentinal basis. 

 L I. Intermediate layer of the enamel organ. 

 in. Involution of epithelium (enamel organ). 

 j. Jaw. 

 j. e. Cartilage of jaw. 



n. Neck of enamel organ. 

 o. Odontoblasts. 

 p. Pulp. 

 pr. Processes of odontoblasts. 

 r. Reticulation. 

 ri. Hidges. 

 s. Space left by shrinkage of tissues. 

 t. p. Tooth papilla. 

 t. Tubule. 



ii. Limit of enamel layer. 

 Zeiss Oc. Ill was employed for all the sections. The objective is stated for the 

 different figures. 



Figure 1. Membrane lying between enamel and enamel cells of molar of rabbit. 



A. IE n face view, the membrane is seen to be not homogeneous, but the 

 reticulation and enclosed disks have a different structure. 



B. Side view which shows the reticulation to be elevated into ridges. 

 Two enamel cells and portions of others remain attached, fitting in be- 

 tween the ridges. Obj. ^ immersion. 



