OUR BEST FEATURES 



human tooth becomes essentially like the germ 



of the shark's tooth. However, in order to defend 



tooihpouch 



fnoul/icairili/ 





lou^er/aKT 



t00ih-6parmi7 



B 



.ifc-^ifih'x^^^ tooth juouch 

 tongue •Tri:v :\>;:iW L_ m 



mmm 



ioiirer 



Meckel's, 

 cartilageV}:'^ 





Fig. 71. Three Embryonic Stages in the Development of Human 

 Teeth (A, B, from Eidman after Ahrens; C, after Corning). 



(A, B, from Entw. d. Zahne . . ., Hermann Meusser, Berlin; C, from Lehrb. d. 

 Entw. des Menschen, J. F. Bergmann.) 



For details, see p. xxix. 



the validity of these comparisons it is essential to 



note that we are not leaping at once from shark 



135 



