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A MANUAL OF DENTAL ANATOMY. 



tion of the tooth ; the enamel of a tooth prior to its erup- 

 tion having a chalky, opaque surface. 



The enamel of the teeth of reptiles is developed from an 

 enamel organ which at no time possesses any stellate tissue ; 

 this is also the case in all fish which I have hitherto ex- 

 amined. In the poison fangs of snakes the enamel cells, 



over the interior of the poison tube, appeared to be trans- 

 formed into a stellate reticulum, which change in this case 

 would appear to be a retrograde metamorphosis. 



The nuclei of the enamel cells, which lie at the extre- 

 mities furthest from the enamel, appear to recede as calcifi- 

 cation goes on ; they do not exercise any special influence 

 on the process as far as can be seen. 



(*) Transverse section of the tooth sac of a poison fang (Viper). The 

 crescentic pulp (a) is surrounded by a layer of dentine (d) ; external to 

 this is a layer of columnar enamel cells, which, upon the exterior of the 

 tooth, upon which a thin layer of enamel is to be formed, are large con- 

 spicuous cells. Where they pass in between the horns of the crescent, 

 into that part which will ultimately be the poison canal, their character 

 is lost, and their place taken by stellate cells (/ ). No enamel is formed 

 in this latter position. 



