A YEAR IN SCIENCE 107 



and arrangement of the minute elevations (papillae) 

 on the upper surface? 



D. The teeth. 



1. Teeth differ in minor points from one another, 

 but in all, three parts are found : one, seen in the mouth 

 and called the crown of the tooth ; a second, imbedded 

 in the jawbone and called the root; and between the 

 two surrounded by the edge of the gum, the neck of 

 the tooth. 



2. Count the teeth in the upper and lower jaws. 

 How many in all? Describe the edges of the front 

 teeth (incisors). How many teeth have this sharp 

 cutting edge? How does the tooth (canine) next to 

 the incisors differ from the other teeth? What is its 

 function? How many teeth have two points to the 

 crown? These are known as bicuspids. What is the 

 character of the last three teeth? What is their func- 

 tion? These are the molars. Do you have all the 

 molars? Why not? 



E. Tonsils. 



The opening from the back of the mouth leads into 

 the throat. Press the tongue down and note the 

 almond shaped elevations at the sides of the throat. 

 These are called tonsils. 



Exercise 72. Alimentary Canal and Digestive 

 Glands. (Demonstration.) 



Object: A study of digestive organs. 

 Apparatus 



Models of digestive organs Charts 



