288 DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 



craniad of the lingual crossing ; the separation has likewise advanced 

 through the whole extent of the flange and reached a point where the 

 attachment is by means of the proliferation keel. No flange being 

 present, there can be no intermediate element. The duct with a cir- 

 cular orifice is first found in our series in the embryo of 51 millimeters. 

 The advance of the duct is rather slow and somewhat unequal in 

 early stages. The whole mouth is lengthening, and the advance of 

 the keel is not able to maintain itself against this greater growth. Its 

 cranial extremity, while successively farther in advance of the Ungual 

 crossing, is separated from the cranial end of the lingual sulcus by an 

 increasing distance. The following measurements were taken upon 

 the right side of well-oriented embryos. They refer only to the at- 

 tachment of the anlage ; its sprout and free duct are not considered. 

 The confluence of the two hngual sulci in these embryos corresponds 

 to the frenulum. The lingual crossing has been explained to refer 

 only to the fibers of the nerve, and in stages where two branches are 

 present, to the larger caudal one. The distance between these two 

 points affords an index of the growth of the region as a whole. With 

 regard to the submaxillary keel, its caudal end is easily recognized ; 

 craniad it diminishes so gradually that it is not easy to tell exactly in 

 what section it stops ; another observer might easily add a section to 

 the counts, or take one away. The sections are 13.3 /x in thickness. 



Embryo 



No. 223 

 13.5 mm. 

 No. 216 

 15 mm. 

 No. 259 

 17 mm. 



Confluence of 



LiNGu.^L Sulci to 



Cranial End of 



Submaxillary 



Keel 



267 

 246 

 320 



Length of Sub- 

 ma.\illary at- 

 tachment 



267 



End of Submaxillary 



Keel to Lingual 



Crossing 



•13-3 



13 



Confluence of 



Lingual Sulci 



TO Lingual 



Crossing 



547 

 547 

 626 



These are merely individual measurements from embryos that were 

 *The distal extremity of the keel is 13.3 /u. caudal to the lingual nerve. 



