320 Herr Paul Frcund on the Development 



The opening of the enamel-bell of the rudimentary tooth 

 is, like that of the large incisor, directed backwards. Within 

 it we do not find, as in the case oi Lepus, a well-formed tooth 

 of dentine, but a small, inconsiderable, almost solid dentine 

 cusp, into which from the inner side only a narrow cord of 

 connective tissue enters. This cusp, too, appears to be no 

 longer enveloped on all sides by epithelium. With reference 

 to the neck of the enamel-organ of the incisor, which follows 

 after it, there is nothing more to be said than that at its 

 starting-point from the dental fold it is broadly fused with 

 the neck of the enamel-germ of the rudimentary tooth. 



The position of the germ of the rudiment in the upper jaw 

 is explained by model fig. 14. We observe that it is situated 

 in front of the enamel-germ of the large incisor. The enamel- 

 germ of the rudimentary tooth of the upper jaw is likewise 

 attached to a long neck, which passes obliquely upwards and 

 unites with the massive neck of the large incisor of the pre- 

 m axil la. Here also, thoiigli certainly less decidedly than in 

 the lower jaw, the irregularity of contour is repeated. The 

 opening of the enamel-bell of the rudimentary tooth is directed 

 backwards and upwards. Inside it the pulp surrounds a 

 delicate little cap of dentine. Figs. 11 and 12 will explain 

 these statements. Fig. 1 1 gives a representation of the ar- 

 rangement magnified nearly fifty times. We see from the 

 figure that the enamel-germ of the rudimentary tooth and that 

 of the large incisor are surrounded by one and the same thick- 

 ened envelope of connective tissue. Fig. 12 shows from the 

 same section the enamel-germ of the rudimentary tooth mag- 

 nified nearly two hundred times. 



With reference to paragraph no. 4 the following remarks 

 must be made : — Fig. 7 shows, magnified one hundred times, 

 a section through the anterior rudimentary enamel-organ, 

 which is situated close in front of the orifice of Stenson's 

 canal. We also get a sectional view of the portion of the 

 dental fold belonging to it ; but in this section the fold is in 

 connexion neither with the epitiielium of the oral cavity nor 

 with the transversely-directed neck of the enamel-organ. 

 Both, however, lie together in an envelope of connective 

 tissue, which is packed with nuclei and consists of concentric 

 layers. In the interior of the enamel-bell distinct enamel- 

 pulp is found : a dentine germ could not be distinguished. 

 The most superficial nuclei ^f the pulp appeared clearer : this 

 is somewhat exaggerated in the figure. They were separated 

 from the deeper-lying dark ones by a transverse cleft, which 

 perhaps represents a blood-vessel. 



Fig. 8 shows the arrangement of the structures, magnified 



