e digestibility of a food necessarily
indicate the economic uses that will be made of it by the body? 674. How
is it possible for one food containing 10 per cent of digestible
protein, and other nutrients in like amounts, to be more valuable than
another food with the same per cent of digestible protein and other
nutrients? 675. How is it possible for one food to contain less total
protein than another food and yet be more valuable from a nutritive
point of view? 676. Why is it necessary to consider the mechanical
condition of a food and its combination with other foods, as well as its
chemical composition? 677. What effect does lack of a good supply of air
have upon the completeness of the digestion process? 678. In what ways
does the digestion of food resemble the combustion of fuel? 679. What is
gained by a study of the digestibility of foods? 680. Why may two foods
of the same general character give different results when used for
nutritive purposes?

CHAPTER XVI

COMPARATIVE COST AND VALUE OF FOODS

681. To what extent do the nutritive value and the market price of foods
vary? 682. How is the value of one food expressed in terms of another
food? 683. How determine the amount of nutrients that can be procured in
a food for a given sum of money? 684. How compare the amounts of
nutrients that can be procured in two foods for a given sum of money?
685. How is it possible to determine approximately which of two foods is
cheaper, when the price and composition of the foods are known? 686. To
what nutrient is preference usually given in assigning a value to a
food? 687. When the difference in this nutrient between two foods is
small, then the preference is given to what nutrients? 688. At ordinary
prices, what are the cheapest vegetable foods? 689. What are among the
cheapest animal foods? 690. Why is it not possible to determine the
value of a food absolutely from its composition and digestibility? 691.
Why is it necessary to consider the physical as well as the chemical
composition of foods? 692. What proportion of the income of the laboring
man is usually expended for food? 693. What are the most expensive
foods? 694. What foods furnish the largest amount of nutrients at the
least cost?

CHAPTER XVII

DIETARY STUDIES

695. What is a dietary study? 696. How is a dietary study made? 697.
What is the value of the dietary study of a family? 698. To what extent
does the protein in the dietary range? 699. Why is