46 ORGANS OF DIGESTION AND ALIMENTARY TRACT. 
are connected with the terminal filaments of the gustatory nerve, and 
are made up of two varieties of cells, viz.: gustatory cells of a delicate 
fusiform shape and sustentacular cells of flattened shape located 
between the former. : 
Both varieties have a single nucleus. The gustatory cells at their 
free ends terminate in a fine cilium like process. Their proximal ends 
are usually branching and are believed to be directly connected with 
the entering nerve fibres. 
SALIVARY GLANDS. 
Name the salivary glands. 
Parotid, sub-maaillary and sub-lingual. 
What is the structure of a salivary gland? 
It is composed of a number of lobules surrounded by a loose con- 
nective tissue. Each lobule is made up of a group of somewhat saccu- 
lar alveoli, from each of which a duct passes, uniting with the other 
ducts to finally pass into the main excretory duct of the gland. Each 
alveolus is surrounded by a basement membrane, upon which are 
arranged large polyhedral cells with single nuclei. These cells may 
appear to fill the alveolus entirely. Between these cells and the base- 
ment membrane are crescentic masses of flattened cells, called the 
“ crescents of Gianuzzi.” They are supposed to take the place of the 
gland cells when they are destroyed. The ducts are lined with cylin- 
drical epithelium. 
PHARYNX. 
What is the structure of the pharynx ? 
It is a fibro-membranous tube surrounded by voluntary muscle tissue 
and lined by mucous membrane. The upper portion has ciliated 
epithelium continuous with that of the nasal passages. Below the 
level of the soft palate it is lined with a layer of stratified epithelium. 
In certain parts it contains a large amount of lymphoid tissue in the 
mucous membrane. 
CSOPHAGUS. 
Describe the structure of the esophagus. 
It has an outer fibrous coat within which is a muscular coat in two 
layers, the outer of which runs longitudinally, and the inner in a 
cireular direction. In the upper part of the cesophagus the muscle 
fibres are striated, while in the lower portion they are non-striated and 
