1 66 PHYSIOLOGY. 



The Care of the Teeth. The teeth need careful atten- 

 tion. They should be thoroughly brushed at least twice a 

 day, on rising and on going to bed. It would be better to 

 clean them after each meal also. If a tooth powder, recom- 

 mended by a reliable dentist, is not used, a good white 

 castile soap will serve well. It is better to use tepid water. 

 If the teeth are not thoroughly cleansed the particles of 

 food which remain will soon begin to decay. This decay 

 is caused by the growth of germs, usually some kind of 

 bacteria, and the decay thus begun is likely to develop 

 acids which attack the limy material of which the teeth are 

 composed. When it is necessary to take acid medicines, 

 care should be taken not to let them come in contact with 

 the teeth. Sweet substances are very likely to decompose 

 and form acids ; so we must clean the teeth after eating 

 candies. Toothpicks are useful in removing the larger 

 particles. But in using toothpicks care should be taken 

 not to dislodge fillings. The teeth should be examined 

 twice a year by a dentist, and any cavities promptly filled. 



The Salivary Glands. The salivary glands make the 

 saliva and pour it into the mouth. There are three pair of 

 salivary glands the parotid, just back of the angle of the 

 jaw, under the ear; its duct runs forward under the skin 

 of the cheek, and opens on the inside of the cheek opposite 

 the second molar of the upper jaw. The submaxillary 

 gland lies under the angle of the jaw ; its duct opens under 

 the tongue near the front of the mouth. The sublingual 

 gland is in front of the submaxillary and empties near the 

 same place as the submaxillary. 



Dissection of the Salivary Glands. The salivary glands of a 

 rabbit or cat may be found near the base of the ear and under the angle 

 of the jaw by removing the skin from the side of the head and neck. 



