TOOTH-GERMS IN^ A AVALLABY. 931 



which is attempting but faiHng to develope ; it has not the 

 " concentric " appearance of a vestigial tooth-germ such as one 

 so often sees as the last evidence of existence of a predecessor to a 

 calcified tooth. 



Rapidly succeeding the calcified tooth b is a well-defined flask- 

 shaped dental rudiment lying in a vevy superficial position in the 

 jaw. This, though close to, is quite independent of any of the 

 other tooth-germs here present and will in the meanwhile be 

 referred to by the letter c (text-fig. 184). 



Text-fio-. 184. 





^T/", / ^ / »$ > • •••1/'//' J*t/-': ' ' ' ( 



y '/ '/.''^ '- ■ ■ ««'"'»• •'..^.•••''' ' - ', 



^; ■, • . . •• , • -r^ ,, • ■ 



Section showing flask-shaped rudiment of tooth-germ c. 



At this jDoint the dental lamina runs horizontally inwards, as 

 in the upper jaw. It forms a t.hickened band of cells lying some 

 distance below the tooth-germ c. Tracing this band t)ack wards 

 it quickly becomes connected with the upper part of the enamel 

 organ of a large tooth (d) in which the dental tissues are difi:eren- 

 tiated and which extends through several slides. In relation to 

 the neck of this enamel organ is a lingually situated downgi'owth 

 of the dental lamina indicating a potential successor (ds) to the 

 tooth d. From this point the tooth-band vanishes for some 

 distance (text-fig. 185). 



As the tooth itself dies out the dental lamina once more comes 

 into prominence and gives rise to an enlargement indicating in our 



