It therefore seems advisable to spend at least as much for fruit and vegetables as for meat and fish; also to spend at least as much for milk as for meat (or for milk and cheese as for meat and fish).

At ordinary prices eggs are about as cheap a food as meat, and cheese (like milk) is much cheaper than meat in proportion to its food value. Eggs and cheese can therefore be substituted for meat to any extent desired in the individual dietary without detriment to its nutritive value and usually with good economy.

General adoption of a dietary such as we now believe to be best would call for more milk and perhaps more vegetables and fruit than now come to our city markets; but more of these foods will be produced and marketed as the demand for them increases. Moreover an increased demand for these foods and a correspondingly decreased (per capita) demand for meat, so far from causing any serious "dislocation of industry," will help to facilitate natural evolution of American agriculture. With increasing population on stationary area farming necessarily becomes more intensive. Beef is produced less by the grazing of cattle on free ranges of unbroken prairie and more by the feeding of grain and other cultivated crops. For a given amount of food consumed a dairy herd yields a product of greater food value than does a herd of beef animals. An increasing ratio of milch cows to beef cattle is naturally to be expected with the development of a more intensive agriculture and will be to the advantage of producer and consumer alike. In regions adapted to dairy farming but too remote from large markets to ship in the fresh state we may anticipate an increasing production of condensed and dried milk and of butter and cheese. An increased production of fruit and vegetables should also be a natural result of a more stable and intensive agriculture. At the same time the concentration of population in large cities increases the expense of transportation and makes the cost of retail distribution a serious item, especially in the case of bulky products with a relatively low value per pound. Cabbage, potatoes, and root crops can be produced at a low cost per ton, but the percentage of the cost of production which must be added when they are distributed through modern retail agencies tends constantly to increase.

The more highly perishable fruits and vegetables having a higher cost per pound or ton are now successfully transported in transcontinental carload shipments. Precooling and lowered temperatures in refrigerator cars, secured by the use of salt with ice, promise to reduce still further the losses incident to their transportation.

Cold storage tends to equalize prices throughout the season on such perishable foods as butter, cheese, and eggs, and secures a supply of other fresh foods such as apples, of good quality, throughout almost the entire year. With the perfection of facilities for more rapid distribution in cities after removal from freezing temperatures the number and quantity of vegetables and fruits so preserved should increase greatly. The canning industry has already developed to enormous proportions and it seems likely that drying processes will be applied to a constantly increasing number of the more bulky vegetables.

The physical and economic wastes in marketing are being reduced by various agencies in the United States Department of Agriculture, now largely consolidated in the Bureau of Markets, and in general the supply may be trusted to keep pace with the demand in the gradual shifting of emphasis from meat toward dairy products, vegetables, and fruit, which seems to be clearly desirable both in view of our present knowledge of nutrition, and in the light of our agricultural situation.

The broader and more accurate conception of food values which is made possible by the recent advances in the chemistry of food and nutrition will guide the judgment both as to the proper emphasis to be placed upon each type of foods in the dietary and as to the wise selection among foods of the same type. It supplies the economic justification for the purchase of certain foods which would appear expensive if considered simply as sources of proteins, fats, and carbohydrates, and, on the other hand, it shows that some foods which are economical sources of protein and energy are also of high nutritive value in other respects.

Making due allowance for all known factors which affect the nutritive value of foods, there remain large discrepancies between nutritive value and market cost, and correspondingly ample opportunity for the exercise of true economy in the choice of food materials.