114 DIGESTION 



is finally caught as a semi-solid mass in a sharp curve 

 which lies in the left groin. From this, it is ejected at 

 intervals. 



EXPERIMENTS AND DEMONSTRATIONS 

 The Alimentary Canal 



Materials: Sound and diseased natural teeth such as can be 

 obtained from a dentist; dilute hydrochloric acid or vinegar; 

 rabbit such as can be bought at a market ; a short piece of the 

 small intestine of a recently killed calf or sheep; alcohol, 50 

 per cent strength; normal salt solution; sheet of fine emery 

 cloth; microscope; fine saw; hand lens. 



1) Teeth: Soak sound teeth in warm water for one or two 

 days ; saw some lengthwise, others crosswise, and smooth on 

 emery cloth. 



a) Examine the structure. 



b) Demonstrate decayed teeth. 



c) Test the effect of an acid upon a tooth. 



2) Salivary glands: Dissect away the skin from the whole 

 ventral aspect of rabbit and note salivary glands : 



a) Below and back of the ear, the pink mass of the parotid 

 gland. (It is difficult to trace the duct which has its outlet on 

 the inside of the cheek). 



b) Just inside the angles of the lower jaw, the rounded 

 masses of the submaxillary glands. 



c) Farther forward, under the tongue, the narrow sublingual 

 glands. 



3) Mouth and throat: Examine the muscles moving jaw. 

 Cut away the muscles on one side of mouth and neck, exposing 

 cavities of mouth and throat. Identify and sketch the 

 following : 



a) Teeth; tongue; and hard and soft palates. 



b) Cavity at back of mouth and its connection with nasal 

 cavity ; tonsils ; muscular walls of pharynx ; larynx ; epiglottis ; 

 and the opening into esophagus. 



4) Esophagus, stomach and intestines: Carefully cut away 

 the front walls of chest and abdomen. After examining and 



