52 THE DEVELOPMENT OF THE SALIV.\RY GLANDS IN MAN 



into the free duct of the submaxillary (p), while the other two are 

 parietal, one lateral to the submaxillary, the greater subhngual (/o), 

 the other mesal, the apical gland (ii). 



The submaxillary anlage in its cranial sections appears as a small 

 keel attached to the fundus of the still open sulcus (Fig. 7, p). As the 

 lingual crossing is approached, it forms a massive flange, increasing 

 both in height and thickness, while the lingual sulcus is reduced to a 

 shallow furrow indenting its base (Fig. 12), and the other two 

 flanges appear attached to its sides. At the lingual crossing it sepa- 

 rates from the sulcus and is continuous with the solid submaxillary 

 duct (Figs. 13-17) ; yet the nature of its separation is such that caudad 

 of the duct a low flange remains attached to the sulcus, wliich from this 

 circumstance has been termed the postglandular flange (Figs. 14-17, 

 ij). This I take to be a persistence of the attached border of the 

 triangular submaxillary anlage of younger embryos (Nos. 2 and 6), 

 which has escaped destruction in the solution of continuity incident 

 to the freeing of the submaxillary duct. It is itself constricted at its 

 base, and has in some of its sections a second similar narrowing near 

 its middle, so that it is almost divided into two small circular areas. 

 There are no sprouts arising from the flange, which has itself entirely 

 disappeared in the 22 millimeter embryo. The constrictions may 

 therefore be instrumental in its reduction ; yet they resemble closely 

 the furrows, which in the cat are the means of freeing such structures 

 as the orbital inclusion and the duct of the greater sublingual gland. 

 The postglandular flange is present in that form also and is reduced 

 without constriction. It is probable, therefore, that as the anlage in 

 man is of somewhat greater development than in the cat, some other 

 primate may retain this element in the adult as one of the components 

 of its submaxillary complex (vide Part III). 



Of the two parietal anlages the lateral has the greater breadth. 

 Its free angle presents a small spherical enlargement (Fig. 12) which, 

 in the next section (Fig. 13), is free in the mesenchyme. The cranial 

 portion of this crest is attached to the lingual sulcus immediately 

 lateral to that of the subma.xillary ; in the lingual region it is attached 

 directly to the flange of the larger gland. At the point of separation 

 of the submaxillary the conditions differ on the two sides ; on the right it 

 retains the connection with the submaxillary, on the left it is attached 



