130 VETERINARY DENTAL SURGERl, 



the sixth week of intra-utcral life (in the human 

 foetus), a groove appears along the border of the 

 future jaws, called the primitive dental groove, 

 which is lined by the membrane of the mouth. At 

 the bottom of this groove projections papilhu 

 spring up, corresponding in number with the tem- 

 porary teeth; these gradually increase in size and 

 acquire the shape of the future teeth. 



Whilst the growth of the papillae are going on, 

 partitions are formed across the groove by which 

 they become separated from each other. These par- 

 titions subsequently form the bony sockets. 



The formation of these partitions places each 

 papilla in a separate cavity. Concurrent with this 

 process small growths take place upon the mem- 

 brane of the mouth just as it dips into the papillary 

 cavity or follicle which finally, by union "with other 

 growths, form a lid which covers the papillae in a 

 closed sac or bag. 



Before a final closing of the follicle, a slight 

 folding inwards of its lining membrane takes place. 

 This folding inwards of the membrane of the prim- 

 itive groove is for the purpose of forming a new 

 cavity the cavity of reserve which furnished a 

 delicate mucous membrane for the future formation 

 of the permanent tooth. 



From a study of this, it will be found that the 

 cavity in which a permanent tooth is developed is a 



