DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 261 



proliferation is not very active. Only the one described in the 

 70 millimeter embryo has a branch. 



A few are constricted at their attachment to the oral epithelium. In 

 a very few the constriction is completed, and the orbitoparotid, sepa- 

 rated from the oral epithelium, lies isolated in the mesenchyme, and 

 becomes an inclusion. Five cases were found in the embryos of our 

 series. 



The earhest is in the 18.5 millimeter embryo, No. 24c), on the left 

 side (Fig. q8, iS). It is a small, cylindrical solid mass of ceils, deeply 

 staining throughout and placed close to the buccal sulcus, on the level 

 of which it lies. Its cranial extremity approaches the oral epithelium, 

 only a miitimal quantity of mesenchyme intervening. Caudad the 

 separation is somewhat greater. It is situated behind the middle of 

 the orbitoparotid interval, wliich in tliis embryo has a definite caudal 

 limit in the sprout of the first orbital gland. In its whole length it is 

 promasseteric, that is. hes cranial of the plane in which the sloping 

 border of the muscle crosses the buccal sulcus, which I have termed the 

 masseteric point. Reckoned by sections, its measurements are as 

 follows : — 



Length, 10 fi. 



Distance from parotid attachment, 160 fi. 



Distance from the masseteric point, 120 /Ji. 



Distance from first orbital, 107 /«■. 



Length of orbitoparotid interval, 277 /".. 



On the opposite side of this embryo, in a nearly symmetrical position, 

 is an orbitoparotid sprout constricted at its attachment and, in view 

 of the condition just described, evidently on the point of separating 

 from the oral epithelium (Fig. 99, 17). 



In the 21 millimeter embryo, No. 242, a slightly larger inclusion is 

 present on the right side. This also is soUd, but has a pale center, and 

 tapers to a point caudad. It follows the direction of the buccal sulcus, 

 close to which it lies, and is entirely promasseteric. Its dimensions 

 follow : — 



Length, 53 fi. 



Distance from parotid attachment, 160 fi. 



Distance from masseteric point, 93 m- 



