No. 2.] ON THE GUSTATORY ORGANS. 1 8/ 



ous, wavy, sub-parallel folds. Those of the lateral borders have 

 a more or less longitudinal direction, and are continued from 

 each side of the tongue on to its under surface, meeting in front 

 of the frcenum. I found some difficulty in identifying fungi- 

 form papillae. There appear, however, to be a few of this type 

 scattered here and there between the folds. The circumvallate 

 papillce are ten to twelve in number. They are in the form of 

 an inverted V, the apex of the V being about 21 mm. from the 

 base of the organ. No lateral gustatory structures were de- 

 tected. 



The folds of the dorsum measure on the average 0.60 mm. in 

 height and 0.70 mm. in breadth. They are flattened or slightly 

 convex on top, and are covered with a fairly uniform layer of 

 epithelium. The epithelium is a trifle thicker on the upper sur- 

 face than at the sides and, in places, appears to be somewhat 

 cornified. The mechanical papillae covering the anterior portion 

 of the dorsum are wedge- or cone-shaped, and measure 0.50 mm. 

 in height and 0.40 mm. in breadth. They bear kt their upper 

 part from one to three recurved spinules. The epithelium 

 sheathing the papillae is partly, and that composing the spinules 

 wholly, cornified. Underlying the papillae, and only separated 

 from them by a thin layer of mucosa, is a large amount of fat 

 in the form of lobules and groups of fat-cells. 



Gustatory Structures. 



The Circiwivallate Papillce. — The papillae vary greatly in size. 

 One of the larger ones measured 2.30 mm. transversely, and 

 was I mm. in height. At their upper part they break up into 

 many secondary papillae. In some papillae the upper portion is 

 cleft and furrowed. The trenches vary in width and depth. 

 Nerve-fibres enter the papillae at their base, and, towards their 

 upper part, divide and form a rather coarse plexus. Serous 

 glands are not very abundant. Their ducts, which are often 

 very large, open at the bottom of the trenches. There is a 

 great abundance of fat in the mucosa and submucosa, and 

 groups of fat-cells also occur within the papillae. The bulbs are 

 far from numerous. They differ in size and shape, and are very 

 irregular in their distribution. One of them measured 0.060 mm. 

 in length and 0.036 mm. in breadth. 



