1 82 TUCKERMAN. [Vol. IV- 



General Description. — The organ is 156 mm. in length, 

 45 mmo in breadth, and 20 mm. in thickness. Anteriorly it is 

 free from the floor of the mouth for 73 mm., or nearly half its 

 length. The fore part of the papillate surface is impressed by 

 a well-marked mesial groove. Posteriorly the groove is con- 

 tinued as an indistinct raphe to the base of the organ. The 

 fungiform papillae are quite evenly distributed over the dorsum 

 and sides from the circumvallate area to the tip. They resem- 

 ble minute white beads, being largest posteriorly and gradually 

 decreasing in size as they approach the anterior limits of the 

 organ. The extreme posterior region and sides are covered as 

 usual with coarse, fleshy, recurved papillary elevations. The 

 under surface, except at the margins, which are somewhat 

 wrinkled, is quite smooth. The circumvallate papillae are two 

 in number. They are on the same transverse line, 13 mm. 

 apart, and 26 mm. from the base of the tongue. At a short 

 distance from the base, near the line of union of the upper and 

 lower surfaces, the lateral gustatory organs are easily distin- 

 guishable. A line dividing the circumvallate papillae at their 

 centres, if continued on to the under surface of the tongue, 

 would pass through the posterior end of the lateral taste organs. 



Gustatory Structures. 



The Circumvallate PapillcB. — The papillae are laterally in- 

 voluted, and measure 1.25 mm. in diameter and 0.90 mm. in 

 height. Their summits are more or less verrucose, and project 

 somewhat from the trenches. The sides of the papillae are 

 quite symmetrical, and the trench encircling each is uniform in 

 width. Serous glands are sparingly present, and their ducts 

 open usually at the bottom of the trench. The bulbs are dis- 

 posed in sixteen closely packed tiers, filling the inferior half of 

 the papillary wall. A few bulbs are scattered at irregular inter- 

 vals on the outer wall of the trench, and, from some indications, 

 it is not improbable that isolated ones may also occur on the 

 upper surface of the papilla. Judging from horizontal sections, 

 there appear to be at least ninety bulbs in a tier. They meas- 

 ure 0.060 mm. in length and 0.031 mm. in breadth. 



Tlie Lateral Gtistatory Organs. — These organs are 7 mm. in 

 length, and consist of nine or ten irregular folds. The furrows 

 vary in width and depth, the average depth being about 0.55 mm. 



