928 



DR. A. HOPEWELL-SMITH AND DR. H. W. MARETT TIMS Olf 



definite shape. This gei-m will for the present be indicated by 

 the letter A. 



From a point just external to the point of connection of the 

 neck of the en?anel oi'gan of ^4 to the oral epithelium, the tooth- 

 band passes horizontally inwards towards the middle line 

 (text-fig. 181)*. This rapidly increases in size, forming on section 

 a conical mass of cells which soon loses all connection with the 

 oral epithelium. From the histological characters of the cells 

 and from the fact that in the more posterior sections a portion 

 of the stellate reticulum of the enamel organ is visible, this 

 structure must be regai'ded as a second tooth-germ (B). 



It is considerably larger than the preceding germ A, though 

 there is not the same amount of difterentiation into the more 

 typical dental tissues. 



Text-fip. 182. 



Section tlirough the tootli-germ B at its deeper end. 



The independent connection of the enamel organ £ with the 

 oral epithelium shows that it is not to be regarded as the 

 morphological successor to A . 



To neither A nor B are there either palatal or labial down- 



* Owing to the difficulty of accurate orientation, the anterior sections of a jaw'cut 

 in the vertical-transverse direction will be in a plane parallel with the outer surface 

 of the jaw. This has been borne in mind in describing the relative positions of the 

 various structures. 



