THE STUDY OF THE MOUTH. 33 



kind could you secure the largest amount 

 for ioc.?) 



4. Which kind of food material is most ex- 



pensive ? 



5. Which of the three kinds of steak named on 



the chart is the most economical? 



6. About what fractional part of a pound of 



each kind of nutrient is needed each day 

 by an American at moderate work ? (Last 

 line on p. 22 and p. 28.) 

 Which food on the chart comes nearest to 

 supplying the nutrients in the right pro- 

 portions? 



8. Why is it better, therefore, to eat a variety 



of foods rather than a single kind? 



9. On p. 10 learn the definition of (a) the most 



healthful food, (b) the cheapest food, (c) 

 the best food. 



17. THE STUDY OF THE MOUTH. 



Take a position with your back toward a strong 

 light and study your mouth-cavity by means of a 

 hand-mirror. 

 A. Walls of the mouth-cavity. 



1. Press the forefinger against the upper, 



lower, and side walls of the mouth; in 

 which of these regions are the walls rigid 

 (bone) ? in which regions are they yield- 

 ing (muscle)? 



2. What differences do you note between the 



