366 E. A. BAUMGARTNER 



masses, the distribution of blood vessels and the topographical 

 relations of ducts, glands and blood vessels are considered in 

 this study. 



The greater part of the material used was preserved in forma- 

 lin. Serial sections of the entire caudal region of the tongue 

 of the younger fetuses form the basis for the study of the glands. 

 Wax reconstructions of various stages of glandular development 

 were made according to Born's method. 



DEVELOPMENT OF THE GLANDS 



As indicated by Graberg, the vallate papillae first appear as 

 solid epithelial do^\^lgrowths. A surface view of the tongue of 

 a 6.5 cm. fetus shows no papillae under a low power lens al- 

 though the foramen caecum is well developed. However, sec- 

 tions show seven papillae, well defined by epithelial down- 

 growths. Their arrangement is characteristic. No glandular 

 outgrowths are distinguishable. 



The earliest glandular outgrowths from the epithehum appear 

 in an 8.5 cm. fetus. There are nine well developed papillae, the 

 fifth lying in the foramen caecum and forming the apex of the 

 'V.' As yet there are no grooves outlining the papillae. A 

 reconstruction of the anterior papilla of the right side shows a 

 slight indication of a groove surrounding it and the papilla 

 slightly raised above the surface of the tongue. The anlagen 

 of four glands project from the lower border of the epithelial 

 wall, two occupying a lateral position and two a medial (fig. 2). 

 The caudo-lateral anlage is ridge-like wdth two protruding ends; 

 the antero-lateral and the caudo-medial are rounded elevations; 

 and the antero-medial has two slightly extended ends. 



Several bulb-like outgrowths are found on the lower border 

 of the epithehal wall of a vallate papilla from a 9 cm. fetus. 



Of the eight papillae in the tongue of a 10 cm. fetus the one 

 in the foramen caecum is the largest. This one and the two 

 adjoining it on the right side were reconstructed. Deep fur- 

 rows separate the papillae from each other. Of the three pa- 

 pillae modeled, the anterior one is di\dded into four parts by 

 epithelial partitions. Both the partitions and the surrounding 



