MAMMALIAN ALVEOLINGUAL SALIVARY AREA 349 



its independent growth into the niesench}>-nial condensation, which is 

 now well dehned. Caudal to the vertical border a well-marked post- 

 glandular flange extends along the lingual sulcus for 60 fJ- (Fig. 8, 8). 



The crest of the subungualis major has a sagittal length of 215 m- 

 It increases gradually for 75 /^ and then more gradualty declines (Figs. 

 6, 7, 8). It is attached in its first section to the lingual sulcus lateral 

 to the keel of the submaxillary, then to the flange of the submaxillary, 

 behind this to the postglandular flange, and for a caudal section or two 

 to the lingual sulcus, which regains its lumen beyond the flanges. 



In a second embryo of 19 millimeters (Princeton Collection, No. 

 104) a more advanced stage of the anlages has been attained. The 

 sprouts are growing distad freely, that of the submaxillary into its 

 mesenchjnne condensation, that of the subungualis major has de- 

 scended to the level of the Ungual nerve. The flange of the submaxil- 

 lary has largely disappeared and the duct is free as far as the lingual 

 crossing. Its attachment extends a short distance in front of the 

 nerve, and is effected by a narrow epitheUal plate common to it and 

 the subUnguaUs major. The combined anlages have in section the 

 form of an inverted Y, the stem representing the closed Ungual sul- 

 cus, the mesal arm the subma.xiUary, the lateral the subUnguaUs 

 major. It is evident that as the keels extend craniad the folding of 

 the sulcus also continues, and that the anlages are only continuous with 

 one another through the medium of the flange which replaces the 

 Ungual sulcus. 



We have now followed the development of the subUnguaUs major 

 to the period at which Chicvitz begins his account, and have shown 

 that the position ascribed to it by this investigator is secondary, and 

 due to the inrolUng of the alveolingual epithelium incident to the 

 formation of the submaxillary flange. It is possible that this is the 

 explanation of its condition in man also, where Cliievitz describes its 

 attachment to the subma.viUary in an eight weeks embryo: "Von 

 dem oben erwahten epithelkammartigen Gebilde geht an dessen aus- 

 serer Flache ein kurzer rundUcker Forsatz ab, welchen ich, namentlich 

 gestiitzt auf eine bei einem alteren Embryo gemachte Beobachtung, 

 als die Anlage einer Glandula subUnguaUs deute." 



The anlage is evidently still minute and is so represented in his 

 seventh figure. This, in view of the condition occurring in the pig, does 



