DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 269 



The keel of the first orbital is lateral and almost parallel to the 

 dental ridge for 240 /x of its extent ; the remaining 67 m of the attach- 

 ment are postdental. The distance of the free fundus of the sprout 

 from the termination of the ridge (80 fj.) corresponds precisely with 

 that of the early anlages of the 18.5-20 millimeter embryos. The keel 

 has advanced and lengthened while the sprout has retained its primitive 

 position. It is, however, entirely craniad of the deep facial vein, which 

 is now crossing the sulcus more obliquely as well as at a more caudal 

 point. With reference to the sulcus the caudal portion of the keel of 

 this anlage is now of fundal position, while the prolongation craniad 

 diverges from the sulcus. The fundal position is secondary, for all 

 the early anlages are parietal, and so goes to show that the fundus of 

 the secondary buccal sulcus continues to shift at this period. In 

 view of the position of the sprouts of the second and third orbitals 

 {vide infra) this interpretation is preferable to the assumption that 

 the site of the anlage is variable, even within such narrow hmits. 

 The free tip of the orbital now Hes just at the notch between the 

 palate condensation and that of the tuberosity of the ma.>dllary ; be- 

 tween them the path is free to the orbit. 



The first orbital of the left side corresponds in site and length, and 

 in the indentation of the base of its keel by a minute fissure in a few of 

 its cranial sections. The process of constriction is, however, much more 

 advanced; 100 m only are attached, 220 fi are free. This is a good 

 instance of the independence in rate of the processes of proliferation 

 and constriction. 



The second orbital on the right side springs from the angle between 

 the first and the oral epithehum. Like its fellow of the left side, and 

 the third orbital, it is fundal in position. Both are moderately ad- 

 vanced in development. The second has a length of 200 /x, of which 80 

 are free and form a rather tliick dorsally directed sprout, which is 

 directed towards the orbit on the mesal surface of the deep facial 

 vein. The element of the left side corresponds closely, but a con- 

 siderable interval (100 fi) separates it from the first orbital. On this 

 side the constriction and separation of the first anlage have been 

 accelerated. 



The third orbital is present only on the right side. It has a length 

 of 100 /i, of which 60 ^ are free, and is interposed between the second 



