330 MAMMALIAN ALVEOLINGUAL SALIV'ARY AREA 



view the submaxillary and sublinguaKs major as essentially caudal, the 

 lesser sublinguals as cranial, in origin. Assigning the Barthohnian 

 element to the latter group, the problem for him is the possibiUty of 

 the invasion of the caudal (posterior) field, by an overgrown element of 

 the cranial (anterior) series, which then would simulate the sublinguaUs 

 major. 



While the extrinsic relations of these glands are thus expressive 

 mainly of their degree of development, the intrinsic or reciprocal 

 relations of their ducts, especially in the supramylohyoid portion 

 of their course, have a high degree of morphologic importance, and 

 though shifted from their early position in the embryo, yet retain what 

 is essential in the primitive relationsliips. 



Reichel in a section from an advanced embryo (rodent, probably 

 rat, of 5 centimeters) in which the definitive topography was already 

 attained, shows the elements oriented in a dorsoventral plane. 

 The most ventral is the duct of the submaxillary, of interme- 

 diate position that of the sublingulis major, while the sprouts of 

 the lesser sublinguals are interposed between the latter and the epithe- 

 Uum of the alveolingual gutter. In the adult the bodies of these glands 

 lie lateral to the two ducts as far caudad as the Ungual ner\-e, where they 

 gradually become dorsal as the series extends into the arcus palatinus ; 

 in some cases the mass extends to the mesal side of the ducts or even 

 presents a gutter in which they are lodged (Huntington); but the 

 orifices of their ducts in any case are arranged in rows along the alveo- 

 lingual gutter dorsal to the horizontal ducts of the large glands. The 

 duct of the subungualis major is in contact with that of the subma.xil- 

 lary, and is directly dorsal in the greater part of its course. Near its 

 orifice it deviates to its lateral side, and caudad where the gland ex- 

 tends to the digastric, it crosses the submaxillar^^ dorsally to gain its 

 mesal surface. In cases in which the BarthoUnian element is smaU 

 and Ues lateral to the submaxillary, its duct may be lateral throughout, 

 retaining the embryonic position (man). WTien a secondary subma.xil- 

 lary is present, its duct is interposed between the main duct and that 

 of the sublinguaUs major. The dorsal position of the duct of the sub- 

 linguaUs major is often overlooked in dissections, from the ease with 

 which it can be displaced laterad. In all of Ran\-ier's illustrations it is 

 so represented, but Zumstein, working with serial sections, estabUshed 



