2 So DIGESTIVE ORGANS. [SECT. 1 33. 



in part, connected with them ; the excretory ducts, which proceed 

 from those situated posteriorly, are as much as 6'" in length, and 

 open partly on the surface, partly by funnel-shaped orifices, into 

 the simple mucous follicles at the root of the tongue. 



b. The marginal glands of the root. — Upon the borders of the 

 root of the tongue there are found, on a level with the papilla; cir- 

 eumvallatoB, several of the before-mentioned perpendicular lamel- 

 lated folds, and between them fine openings, which belong to a 

 special smaller group of glands lying in the midst of the expansion 

 of the hyo-glossus and transversa. In the mammalians, these 

 glands, as also the folds in question {Mayers organ), are frequently 

 very much developed (see Br did, 1. c). 



c. The glands of the tip. — Upon the lower aspect of the tip of 

 the tongue, on either side, and in the substance of the lingualis 

 inferior and sti/lo-glossus, are two elongated groups of glands, 6'" 

 to 10'" long, 2'" to 3'" thick, and 3"' to 4'" broad, whose excretory 

 ducts, five to six in number, open upon peculiar fringed folds of 

 mucous membrane parallel to the frenum lingace. These glands 

 were accurately described by Blandhi, and were recently rescued 

 from oblivion by Nuhn. 



§ 133. Intimate Structure of the Mucous Glands. — A.11 the above- 

 mentioned glands entirely agree in all essential points of structure, 

 and invariably consist of a certain number of lobules with a 

 branched excretory duct. The lobules, which, in the simplest 

 glands, amount only to some few (4 to 8), are elongated, pyriform, 

 or sometimes rounded in outline, not unfrequently flattened, and 

 measure 0-5'" to 072'" in length, and o*2'" to 0-48'" in breadth, 

 although they are occasionally almost quite round, and each is 

 placed upon a branch (0-03'" to 005'" broad) of the excretory duct, 

 which latter measures o'li" to 03", or even o"5'" (glands of the 

 root), in length. They consist of convoluted canals (fig. 123), 

 beset with simple and compound vesicular dilatations, and appear- 

 ing to be the immediate continuations of the excretory ducts 

 of the lobules, which, on passing into the lobules, successively 

 divide into a certain number of these canals, mostly without 

 decreasing in diameter. What have been called glandular vesicles 

 (acini), are merely the dilatations and terminations of these 

 canals, or ultimate branches of the excretory ducts. When viewed 

 superficially, and with smaller magnifying powers, they all 

 appear uniformly rounded or pear-shaped; but upon narrowly 

 examining an entire lobule, or, still better, a gland which has been 



