2IO DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



alveolar process and the lower lip as far as the diastemal fold. The 

 derivatives of the buccal sulcus are, in order of their appearance, the 

 orbital inclusion, the parotid, and the inconstant orbitoparotid 

 sprouts, which arise from the furrow in the interval between the 

 parotid and the inclusion. The anlages of the orbital glands are 

 associated with the secondary buccal sulcus and are formed after the 

 inclusion has separated. The inferior alveobuccal glands are a series 

 of simple sprouts in the course of the sulcus of the same name, and 

 constitute the "molar gland" of authors. At a late period when the 

 orifices of the parotid and orbital glands have come to open upon a 

 sagittal ridge {stomal ridge), a few small elements appear in its course 

 and along its ventral limit. These are termed the glands of the stomal 

 ridge. I shall proceed to describe the derivatives of the buccal and 

 secondary buccal sulci in the following order: orbital -inclusion, 

 parotid, orbitoparotid, and" orbital glands. The inferior alveobuccal 

 and the glands of the stomal ridge will be described under the heading 

 of diffuse glands. 



THE ORBITAL INCLUSION 



In the 8.5 millimeter embryo the oral cavity presents appearances 

 in the region of the mandibular nerves which can be attributed to 

 resistartce to its lateral expansion. These are a dorsal tilt of the 

 marginal cavity carrying the buccal sulcus to a higher level ; some 

 degree of conformity in the curvature of -the roof and floor, the con- 

 vexity of the roof representing the palate process ; and, finally, the 

 formation of a rather acute angle at the ental surface of the epithelium 

 of the buccal furrow. This gives the fundus of the sulcus a slightly 

 pinched look (Fig. 6). It was apparent in two sections only on each 

 side. The sections have a thickness of 13.3 M- 



In embryos of 9 millimeters a small but distinct fold is found, not 

 only opposite the mandibular nerve, but extending shghtly craniad 

 of its crossing. In embryo No. 268 it is still minute, having a sagittal 

 length of only 40 ^. In the sections (Fig. 18) it is characterized by a 

 rather abrupt narrowing of the oral cavity to a fissure at the buccal 

 sulcus, and by a slight indentation of theectal outline of the epitheUum 

 dorsad, as though kinked at this point. In embryo No. 106, also of 9 

 millimeters, the process has advanced somewhat ; the fold has a length 



