TEETH OF PIIYSETER 



dental lamina is straight and quite at right angles to the 

 oesophageal epithelium. Beyond the origin of the tooth rudi- 

 ments, as will be seen in the ligures, it is continued onwards 

 in the same straight line as the dental lamina, and it is this 

 region which I have termed above the residual lamina. In 

 neighbouring sections to that represented in Text-lig. 4 (see 

 Text-tigs. 2, 3) the dental and residual laminae show no 

 differences, but the actual tooth germ is more slender. But 



Text- FIG. 5. 



* 



Three sections, near to each other, from the condylar end of the 

 lower jaw, rejiresenting three stages in the growth of the tooth 

 germ. The left-hand figure rej^resents the mitial stage, in which 

 the entire tooth germ is a mere swelling of the dental lamina. 

 Later (the middle figure) the residual lamma becomes differen- 

 tiated ; and the third section shows the comijlete differentiation 

 of the rudiment of the permanent tooth. 



it does not appear ever to vanish between successive teeth, 

 but to be continued as a lamina, the actual tooth germ being 

 local thickenings of this. The residual lamina undergoes no 

 change in the intervals between the teeth, but it may at times 

 terminate in a more club-shaped or at least slightly swollen 

 extremity than in other places. At the very beginning of the 

 series of tooth rudiments of the lower jaw — at the end nearest 

 to the condyles — the rudiment consists (see Text-fig. 5) of 

 a swollen extremity supported by a short stalk. This resembles 



