266 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



time of its formation varies in rather wide limits ; it is present at 18.5 

 millimeters in embryo No. 249 (Figs. 98, 99, 20). In one of the 19 

 milli.-ieter embryos it is again present. In the three embryos of 

 20 millimeters of our series it is present only in two. In all these the 

 anlage is bilateral and presents the same general characters. The 

 oral epithelium has well-defined periderm and basal layers ; the latter 

 alone gives rise to the anlages. There is no evidence of folding, and no 

 fissure is present. In section the anlages are deeply staining, of 

 approximately hemispheric contours, and are sUghtly longer than broad, 

 from 27-40 fi in the section counts. Here, then, the first event is 

 clearly an act of proliferation. 



With reference to the superior dental ridge the position of the 

 laterally placed anlage varies in these embryos. In those of 1S.5 

 and 19 millimeters and in one of the 20 milHmeter embryos there is a 

 short sagittal interval between the termination of the dental ridge 

 and the keel of the first orbital gland. It is not more than 40 /n at 

 the most and has disappeared in the second of the 20 millimeter em- 

 bryos, the termination of the dental anlage and the beginning of the 

 orbital appearing in the same section. 



In all of these embryos the first orbital is situated in advance of the 

 orbital inclusion, from the tip of which it is separated by a variable 

 sagittal interval. The inclusions are now free from the oral epithelium 

 except for their caudal extremities. Their anterior processes are short 

 conical continuations of the partes latae, which now have circular 

 cross-sections and are distmguished from the partes cylindricas by 

 their size alone. The question of the origin of the first orbital anlage, 

 whether from the superior alveobuccal or the secondary buccal sulcus, 

 has been discussed in connection with the orbitoparotid interval. The 

 early anlages are in the plane of the deep facial vein which approxi- 

 mately marks its caudal limit, and it was shown that in the embryos 

 here in question, the relation of the sprout to the orbital inclusion is 

 readily explained by the reduction of the anterior process subsequent 

 to its separation from the oral epithelium. Further, the sprout is post- 

 dental in position, while the orbital inclusion regularly in early stages 

 extends beyond the extremity of the dental ridge. As none of our 

 series possesses a first orbital coexisting with a still attached anterior 

 process of the inclusion, an absolute assignment of the gland cannot be 



