DEVELOPMENT OF SALIVARY GLANDS IN THE DOMESTIC CAT 293 



of the mesenchyme. The anlage is separated by a distinct interval 

 from the hngual sulcus, equal to about half the width of the gutter 

 at this point, and the epitheUum diminishes in thickness towards 

 the sulcus, so that the two anlages cannot in any sense be considered 

 continuous. This independence of the greater subhngual is absolute 

 and maintained throughout development. 



In the 13.5 millimeter embryo, No. 223 (Figs. 133-135), the ridge, 

 which has a sagittal length of 107 /a, extends to the hngual crossing. 

 In the two embryos of 14 millimeters, Nos. 122 and 127, the anlage is 

 of the same character, but shorter. In the first it has a length of 63 /* 

 and stops 13 ^ caudad of the lingual nerve; in the second it reaches 

 the plane of the nerve and measures 90 fj.. 



In the 13.5 miUimeter embryo. No. 189 (Fig. 139), the greater sublin- 

 gual is larger than in the foregoing; its cranial extremity has advanced 

 beyond the lingual crossing. It is relatively broad for its height and 

 bulky as contrasted with the anlages of the other salivary glands. It 

 is at its maximum caudad, thence diminishing craniad, where the keel 

 ceases to project from the ectal surface of the epithelium, and is 

 replaced by a rather ill-defined thickening of the epithelium of the 

 alveoHngual region. This may be shghtly concave. The anlage 

 is clearly a product of prohferation, arising out of a diffuse thickening, 

 unassisted by fold or fissure. 



In embryos of 15-17 millimeters the anlage increases in depth and 

 width ; its caudal portion becomes constricted at the base along the 

 line of its attachment. The cranial extremity continues to merge 

 insensibly with the diffuse thickening of the gutter and shows little 

 tendency to advance, in only a few cases passing the lingual crossing 

 and then only by a few micra. Some of the sections of the keel now 

 show a slight indentation of their base. The fissure is always minute, 

 a mere line in the oral portion of the epithelium and never so deep as 

 the thickness of the epitheUum at the sides of the keel. It is not often 

 present at the extremities of the crest, and never, apparently, is formed 

 by the deepening of the concavity craniad of the keel. It would 

 seem, rather, to be an invagination fissure due to some slight shifting 

 of cells incident to the active proliferation of the keel. In no part of 

 the line followed by the greater sublingual is there ever a preformed 

 sulcus. 



