DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 273 



tal. Along the crest of the stomal ridge open, at nearly equal intervals, 

 the parotid, an orbitoparotid, and the three orbitals, whose general 

 disposition in comparison with the embryo of 51 millimeters shows only 

 increased growth along the lines there estabUshed, without the appear- 

 ance of any new features. The anlages are soHd; in the ducts the 

 centers are' very pale and in some places a minute cleftlike lumen 

 seems to be present. Attention has already been called to the difficulty 

 of determining the presence of small lumina in the salivary anlages ; 

 the rather thick sections of this embryo do "not afford grounds for 

 a definite statement, but suggest that the lumina are being formed as 

 discontinuous clefts between the pale axial cells of the ducts. At 

 their oral extremities the ducts are attached by shorter keels than in 

 earUer stages, markedly constricted at their bases in all except the most 

 cranial sections, which would seem to indicate that their period of 

 advance is drawing to a close. The keels are solid and deeply staining ; 

 there is no appearance of a channel among the cells of the thick 

 stratified oral epithelium, as in the case of the inferior alveobuccal 

 glands, to continue their drainage lines to the surface, which would 

 seem to agree with the apparent lack of continuous lumina in the ducts, as 

 such channels through the epithelium are probably formed under the 

 influence of the flow of fluid incident to the removal of the central cells. 

 Three additional orbital sprouts are now present, arising in series 

 from the secondary buccal sulcus ventral to the bodies of the orbital 

 glands (Fig. 1 14, 2j) ■ They are short solid sprouts springing from the 

 basal layer of the epithelium of the secondary buccal sulcus on its dorsal 

 aspect, and directed dorsad or dorsocaudad towards the orbital mass. 

 They are separated by a distinct interval from the diffuse glands of 

 the fauces, and in situation and direction of growth correspond so 

 closely with the first three orbitals that they seem properly to be in- 

 terpreted as belated members of this series. They are here simple 

 sprouts and show at their origin no appearance of keels. In the adult 

 it will be remembered that the orbital mass at its caudomesal extrem- 

 ity comprises several small elements, resting against the oral epithe- 

 lium, whose ducts open directly into the vestibule at the caudal 

 extremity of the stomal ridge, and beyond it on the surface of the 

 glandular triangle. 



The orbital mass, therefore, represents a series of like elements, the 



