290 



THE SNAKES OF SOUTH AFRICA. 



The Salivary Glands and Teeth. 

 We are provided with incisor or front teeth for biting and 

 tearing our food ; and molars for the purpose of carefully grind- 

 ing up the food before it is swallowed. True, we have canine 

 teeth, with which our primitive ances- 

 tors fought their enemies, before they 

 evolved the idea of using branches of 

 trees as clubs, and stones as weapons. 

 The instant food enters the mouth, the 

 salivary glands pour out their secretion, 

 which is known as saliva. This saliva 

 is very important, for it performs a 

 work which the stomach is unable to 

 do. The saliva has the power of 

 changing the starchy parts of the food 

 into quite another substance. In fact, 

 it partly digests and prepares it for 

 another process which will take place 

 later in the stomach and bowels. 



It is very important that we should 

 chew up our food thoroughly before 

 swallowing it. Parents should take 

 the greatest possible care of their 

 children's teeth. The teeth should 

 be cleaned, and the mouth washed 

 every morning, and at bedtime. The 

 mouth-wash should contain some anti- 

 septic which is not irritating to the 

 gums. Washing or rinsing is not 

 sufficient, It is necessary to use a tooth 

 brush and an antiseptic dentifrice. 

 Without good teeth, the food cannot 

 be properly prepared for the stomach. 

 Good teeth and a healthy stomach are a child's greatest asset. 



Fig. 120. — The t;whole digestive 

 apparatus of a human being. 

 It is about 30 feet in length. 

 (From Blackie's Physiology.) 



The Stomach. 



When the food is swallowed, it goes down a long tube called 



the gullet or OEsophagus. The instant it enters the stomach, 



the gastric nerves receive a stimulus, and digestion begins. The 



stomach is a large, hollow, muscular bag. Embedded in its 



