THE ORGANS OF THE SPECIAL SENSES. 209 



with the teledendrites of nerve-fibres supplied to the taste-bud 

 (Fig. 252). The stratified epithelium surrounding the taste-buds, 

 as elsewhere, contains teledendrites from sensory nerves. 



3. Smell. — The olfactory organ occupies a small area at the top 

 of the nasal vault, and extends for a short distance upon the sep- 

 tum and external wall. Its exposed surface is about equal to that 



Fig. 252. 



Diagram of a taste-bud and its nervous supply. (Dogiel.) a, radicle of the gustatory nerve ; 

 b, radicle of a sensory nerve ; c, epithelial cell ; d, nerve-cell. The shaded part of the 

 figure represents the stratified epithelium lining the sulcus of the circumvallate papilla. 

 Only one of the epithelial or supporting cells of the upper bud is represented in the 

 figure ; the others are omitted. The structure of the lower bud is not shown. 



of a five-cent piece. It is a modified portion of the mucous mem- 

 brane of the nose, which may be divided into this, the olfactory 

 portion, and the general or respiratory portion. 



The respiratory portion of the nasal mucous membrane is covered 

 with a stratified, columnar, ciliated epithelium, with occasional 

 mucigenous goblet-cells, resting upon a basement-membrane. Be- 

 neath this is the membrana propria, resembling that of the small 

 intestine in being rich in lymphadenoid tissue, which may, here and 

 there, be condensed into solitary follicles. Beneath the membrana 

 propria is a richly vascularized submucous areolar tissue, containing 

 compound tubular glands, the glands of Bowman, which open upon 

 the surface of the mucous membrane. These glands secrete both 

 mucus and a serous fluid. 



In the olfactory region the columnar epithelial cells are devoid of 

 cilia, but possess a thin cuticle, and the epithelium rests directly 

 upon the lymphadenoid tissue, without the intermediation of a base- 

 ment-membrane (Fig. 253). Between these epithelial cells are the 



