MAMMALIAN ALVEOLINGUAL SALIVARY AREA 35- 



phylogenctically older companions. If, however, tl cy are composites 

 of these same elements, their priority in appearance indicates merely 

 the acceleration of a portion of a common gland field. The presence 

 of a sulcus seems to favor the appearance of the anlages, in that the 

 sprouts associated with llanges grow more rapidly (submaxillary and 

 parotid) than those without (sublinguahs major, orbitals), but that 

 it is not essential to the process of condensation, which gives rise to a 

 keeled gland, is shown by the history of the sublingualis major and the 

 larger orbital glands. 



4- The glandiferous epithehum of the alveolingual gutter tends 

 thus to produce diffuse simple sprouts. This tendency in early stages 

 IS repressed in the mesal (lingual sulcus) and intermediate areas. 

 Here the keels of the submaxillary and sublingualis major are formed. 

 The potentiahty of these areas is not exhausted in the production of 

 these ducts, as is shown in man by the appearance of other rudiments, 

 and as may be inferred by the presence of simple diffuse glands in 

 the adult opening mesad to the ducts of the large glands (Huntington). 

 5. The submaxillary is a sulcal, flanged, keeled gland. Its prolif- 

 eration is initiated caudal to the lingual crossing, in the transverse 

 plane of the submaxillary ganglion. It advances along the border of 

 its flange to reach the fundus of the lingual sulcus, to the lateral wall 

 of which its keel is subsequently displaced. The duct is freed by 

 constriction and separation of its keel. The lumen is acquired secon- 

 darily. ^ In the region of the flange the duct is freed by a solution of 

 continuity in the flange, portions of which persist for a time attached 

 to the hngual sulcus, the postglandular flange, and to the submaxillary 

 duct, the presumptive anlages of the second submaxillary and the 

 dorsal accessory submaxillaries, respectively. 



6. The subhnguahs major is a keeled gland, not sulcal and, therefore, 

 lacking a flange. Its proliferation is initiated caudal to the lingual 

 nerve. Its keel is attached to the floor of the alveohngual gutter and 

 advances on the lateral side of the submaxillary. It may remain 

 separate from the submaxillary throughout development (cat), or be car- 

 ried by an inrolling of the epithelium of the gutter into the submaxil- 

 lary flange (pig). This circumstance docs not determine the position 

 of its orifice, which is independent in the pig, where its keel retains its 

 independence, and when the submaxillary duct is freed, remains 



