176 ELEMENTS OF HISTOLOGY. [chap. xxi. 



owing to a transformation of the middle layer of the 

 epithelial cells into a spongy gelatinous tissue, due to 

 accumulation of fluid between the epithelial cells 

 of this layer, and to a reduction of its substance 

 to thin nucleated plates, apparently branched. The 



Fig. 105. From a Section through the Tooth and Lower Jaw 

 of Fo3tal Batten. 



a, Epithelium of the free surface of the gum.: 6, the mucous membrane of same ; 

 c, spongy bone of jaw; d, papilla of tooth; e, odontoblasts ; /, dentine: g, 

 enamel ; h, membrane of Nasmyth ; i, enamel cells ; j, middle layer of enamel 

 organ ; k, outer layer of enamel organ. 



outer stratum consists of one or more layers of 

 polyhedral cells, continuous with the deep layers of 

 cells of the epithelium of the surface of the gum. 

 Outside the enamel cap is the gelatinous vascular 

 tissue of the mucous membrane of the gum. 



235. The foetal tooth papilla is a vascular embryo- 

 nal or gelatinous tissue ; on its outer surface a con- 



