78 ANATOMY OF THE RABBIT. 
The parts of the digestive tube may be classified as follows: 
i ORAL "CAVITY: 5. SMALL INTESTINE. 
Oral cavity proper. Duodenum. 
Vestibulum oris. -Mesenterial intestine. 
Jejunum. 
2. PHARYNX. Ileum. 
Nasal portion. 
Oral portion. 6. LARGE INTESTINE. 
Laryngeal portion. Caecum. 
Vermiform process. 
3. OESOPHAGUS. Colon. 
Rectum. 
4. STOMACH. 
The digestive system comprises a variety of functions, both 
mechanical and chemical, and connected directly and indirectly 
with the digestion of food. In the oral cavity solid food is com- 
minuted by the action of the teeth, and is mixed with salivary 
DIGESTION AS secretion, so that it is more easily swallowed 
A PROCESS. and passed along the cesophagus to the 
stomach. The secretion of the oral glands is 
thus important chiefly for its mucous element, but that of the 
parotid especially contains an enzyme, ptyalin, which is capable 
of converting starch into soluble material. Food is further reduced 
to a pulp-like mass in the stomach, while the gastric secretion, 
containing pepsin and rennin, exercises a dissolving action upon 
proteid, and a coagulating action upon milk. The liver secretion, 
known as bile, contains, in addition to coloring materials, salts 
which exert a splitting action upon fats. The pancreatic secretion _ 
contains a variety of enzymes, converting proteids and starches, 
and breaking fats into fatty acids and glycerin. The actions of the 
dissolving enzymes is successive, secretion being dependent to some 
extent on antecedent bodies by which the stimulus for secretion is 
determined. The preliminary processes of digestion refer in this 
way to the mechanical action of food passage along the canal, 
and to the provision of converting enzymes. Absorption, which 
the final object of the digestive process is accomplished chiefly 
in the large intestine through the bloodvessels and lymphatics of 
