DEVELOPMENT OF SALI\'ARY GLANDS IN THE DOMESTIC CAT 243 



and alveobuccal sulcus. In the roof growth in the maxillary process 

 is accelerated mesad and results in the palate process. The corre- 

 sponding region of the mandibular process gives rise to the lateral 

 tongue swelHngs, and these gain a mesal position with reference to 

 the palate processes, which thus become fixed and offer resistance 

 to the expansion of the roof of the maxillomandibular planes. An 

 equal obstacle to its lateral extension is atTorded by the presence 

 of the mandibular nerve and quintus musculature. In these circum- 

 stances the transverse growth of tliis region is impeded in the roof; 

 its epithelial tliickcning long retains its continuity, and the several 

 anlages on their appearance are crowded together ; further, the periph- 

 ery of the plane is sacrificed as the orbital inclusion. Craniad of the 

 masseter space is gained, and near the plane of the anguli, the palate 

 process de\iating mesad and becoming small, more favorable condi- 

 tions obtain. Here the separate anlages first appear and are widest 

 apart, converging and blending as they are followed caudad. An 

 idea may be formed of the relatively enormous and rapid expansion 

 of the floor, when we reflect that the palate processes and lateral 

 tongue swelhngs, being mesal portions respectively of the maxillary 

 and mandibular processes, are in this sense equivalent regions, and 

 that their lateral borders, the hngual and ectopalatine sulci, are to 

 this extent equivalent lines. From both a primitive epithelial tliick- 

 ening extends to the buccal sulcus. Its earlier resolution into separate 

 anlages ventrally and their greater size appear correlated to the 

 rapid expansion of the region, wliile the more lateral position of the 

 dorsal elements and their nearness to the buccal sulcus depend upon 

 the lateral position taken by the palate process with reference to the 

 tongue swelling. With the closure of the palate a readjustment is 

 permitted, and then the dorsal elements come to he more nearly 

 opposite their ventral equivalents, though retaining even in the 

 adult a slightly ectal position, most clearly seen in the relation of 

 the teeth. 



As a consequence of the greater expansion of the ventral region and 

 its greater proportional contribution to the vertical wall of the vesti- 

 bule, the parotid is shifted dorsad, and this would be the case even were 

 its fundal position retained. While no doubt this is the main cause 

 of the displacement of the parotid two minor factors require consider- 



