194 THE MICROSCOPE. 
and backwards. The cone-shaped papille investing the upper 
surface and sides of the anterior half of the tongue do not differ in 
character very materially from ordinary conical papille. About the 
gustatory area and root are thick, fleshy, cone-shaped elevations, the 
apices of which are turned backwards. Fungiform papille of the 
normal type are distributed over the upper surface and sides of the 
organ, attaining their maximum size in the tract directly in front of 
the circumvallate papille. 
The circumvallate papille are three in number and are situated 
well back on the dorsum. They are arranged in an isosceles triangle, 
the apex of the triangle being backwards. At each side of the 
tongue, near the base, is a papilla foliata. The inner border of 
these papille is marked by a fringe of large, fleshy papille, the 
apices of which are directed upwards, inwards and backwards. This 
fringe is continued for some distance on to the glosso-palatine arch. 
GUSTATORY STRUCTURES. 
The Circumvallate Papille.—These papillze show no indica- 
tions of lobation. Their upper surface, which is somewhat uneven, 
overtops the surrounding lingual area. The epithelium covering 
their free surface measures about 0.07mm. in thickness, being a 
trifle thicker than that protecting the sides. The lateral walls of 
the papille curve downwards and inwards, giving them a rather 
constricted base. The trench encircling each papilla is deep, 
narrow, and quite uniform in breadth. Serous glands are fairly 
abundant in the underlying stroma, and also occur within the 
papillary body itself. Their ducts open into the trench at its deeper 
part. Nerves of considerable size enter the papille at their base, 
and their branches (which are for the most part non-medullated) 
radiate to the summit and lateral regions of the papillze, in the 
mucosa of which they cease to be longer distinguishable. 
The taste-bulbs of the circumvallate papille are only fairly 
numerous. They are disposed at the sides in a zone of four to six 
tiers, the uppermost tier being about opposite the middle of the 
trench. I failed to detect taste-bulbs in the epithelium of the free 
upper surface of the papillz, and they were likewise wanting in 
that investing the outer wall of the trench. From horizontal sec- 
tions, made at different levels, I estimated the number of bulbs in a 
tier at fifty. If we allow for five tiers, we shall have two hundred 
and fifty bulbs for each of the three papille. The bulbs present the 
usual amount of variation in size and shape. (Fig. 2 shows their 
external structure magnified 240 diameters.) The mean length of 
the bulbs is 0.057mm., and their mean breadth 0.032mm. 
