MAMMALIAN ALVEOLINGUAL SALIVARY AREA 35 1 



sublingualis major is annexed by the submaxillary flange, yet in the 

 pig it regularly has a separate oritice, while in man the condition is 

 variable. In both the sublingualis major makes its advance by an 

 independent keel, continued along the lingual sulcus close to, but not 

 perfectly distinct from, that of the submaxillary. There is, then, 

 material for an independent duct to be formed by the constriction and 

 separation of the lateral keel. On account of the proximity of the 

 two keels the supposition of their occasional fusion is not difficult, but 

 is unsupported by any evidence. On the other hand there are differ- 

 ences in the anlages of the sublingualis major, in man and the pig, which 

 suggest another explanation. It has been seen that in the latter the 

 sublingualis major is attached to the postglandular flange, and that 

 it retains tliis attachment when the flange of the submaxillary is 

 disrupted to free the larger duct. In man (human embryo of 20 milli- 

 meters) this condition obtains on one side ; on the other the cleft 

 passes dorsal to the Bartholinian anlage, which is attached to the free 

 duct of the submaxillary. Further, in this embryo there are gaps m 

 the crest of the Bartholinian element on both sides. It is suggested 

 that the attachment to the separating subma.xillary duct may so 

 disturb the alignment of the sublingualis major that its proliferation 

 fails to supply the gap and its independent b'ne of advance is lost, with 

 the result that its duct becomes tributary to that of the submaxillary. 

 It remains to mention derivatives of the alveolingual region mesal 

 to the submaxillary. Our knowledge of their development is still 

 extremely meager. Chievitz described a sprout at the cranial end 

 of the Hngual sulcus, which is apparently referable to the apical 

 gland of the tongue. In the 20 millimeter human embryo of 

 the Columbia Collection, there is attached to the mesal lamina 

 of the submaxillary a triangular anlage, similar in structure to the 

 keel of the sublingualis major. In the 22 millimeter embryo this 

 seems to be represented by a more cranially attached plug, which 

 arises from the fundus of the lingual sulcus (Part II, Figs. 4, 11, 12, 21). 

 The attachment has probably been sliifted craniad by a process of 

 constriction, such as frees the keels of the submaxillary and greater 

 sublingual glands. The association of this anlage in the earlier stage 

 with the flange of the submaxillary is very likely due to the shift 

 of epithelium incident to the formation of the flange. 



