2l8 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



along its sagittal segment. Both in this and in the preceding embryo 

 the lateral process is rudimentary. The buccomasseteric nerve Ues 

 close to the caudal border of the pars lata (Fig. 35). 



In the 14 millimeter embryos the separation of the inclusion from 

 the oral epithelium is begun. The region affected is the cranial por- 

 tion of the pars cyhndrica ; here mesenchj-me enters the cleft formed 

 by the separating sulci and the inclusion begins to undergo a lateral 

 as well as a ventral displacement. In embryo No. 211 (Fig. 41) the 

 process is initiated at a point rather farther caudad than usual ; as a 

 rule, it is first seen at the cranial end of the pars cylindrica close to the 

 pars lata (Fig. 43). For the rest, embryo No. 211 requires Uttle com- 

 ment ; the lateral process is rudimentary ; the pars lata shows no ven- 

 tral displacement ; the dorsal separating sulcus does not extend as far 

 craniad as in the 13.5 milhmeter embrj-o nor does it form a broad 

 concavity in the region of the pars lata. The cranial process, which 

 is distinct in the sections, though ill defined on the surface, is separated 

 by a definite, though small interval (ij) from the parotid {12). In 

 embrj^o No. 127 (Fig. 43) the ventral displacement of the inclusion is 

 marked throughout its whole extent. The cranial process runs out 

 into a low ventrally directed flange {16), which prolongs it almost to 

 the parotid (12), from which it is separated only by a small incisure. 

 This embryo illustrates the occasional tendency to continuity of the 

 parotid and orbital folds, a tendency but rarely realized {vide infra). 

 In this embryo, also, the pars cyhndrica is narrowed at its junction 

 with the pars lata. This condition is of rare occurrence ; a solution 

 of continuity at this point has not been observed. 



The 15 milhmeter embr>'os (Figs. 44, 45) show an advance of the pro- 

 cess of separation ; only the tip of the cranial process and the caudal 

 half of the pars cylindrica are now attached. The interval between 

 the inclusion and the secondary buccal sulcus has increased in width; 

 the ventral displacement is also marked. The pars lata on sep- 

 aration loses its dorsoventral flattening and soon becomes circular 

 in the sections, where it is distinguished from the pars cyhndrica only 

 by its larger size. Craniad it tapers to the cranial process, which is 

 prolonged along the buccal sulcus, as in the earUer embryos, by a low 

 ventrally directed flange. In embryo No. 219 (Fig. 44), on the right 

 side this extends mto continuity with the parotid, forming a complete 



