[Sidenote: Nuts as heat producers] The true nut is the seed of trees and shrubs which stores the greater proportion of food material for nourishing the seedling in the form of vegetable oil. The nut is very largely a fuel food or heat producer, therefore among the primitive races, along the warmer belts of the earth's surface, the nut was not of so much importance, but in the northern or colder countries, where the body-heat meets with such powerful resistance from climatic environment, the nut is of equal, if not of more importance than fruits. There are a few miscellaneous articles of food that are classed as nuts, which do not belong primarily to this group. In the following discussion I will take up the several varieties of nuts in the order of their general value as articles of human nutrition: [Sidenote: Pine nuts] [Sidenote: Composition of the pine nut] [Sidenote: The nitrogen factor in nuts] There are several species of pine seeds from many varieties of trees, and from many different countries. The Italian pine seed or nut, called in Italy "Pignon," and in this country "Pignolia," is the refined or cleansed nut, called by the writer "protoid" nut. This is a coined word given to it because it contains the highest percentage of protein of any other food that has yet been analyzed. The "protoid" nut contains 34 per cent protein, 47 per cent oil, 9 per cent carbohydrates, 4 per cent ash, and 6 per cent water. The relative proportion of nitrogen to energy is not so great as in some other food products, such as eggs, or skimmed milk. These contain a large per cent of water, so that the protoid nut, while containing pound for pound more nitrogen than any other known food, has a lower nitrogen factor than foods which do not contain so large a percentage of fat. This same rule will apply to all nuts. They are rich in protein, but because of the large amount of fat which supplies energy in its most condensed form, the nitrogen factor, which is the relation between nitrogen and energy, is often lower in many nuts than in grain. The chief advantage of protoid nuts over other varieties is in their softness, consequently they are more digestible, and more assimilable than any other specimen of the nut family. The pine nuts which grow prodigally in the western part of the United States are not so rich in protein as the protoid nuts, but in other respects are very excellent food. The annual crop of these is about one million pounds, but is variable, a full crop being produced only about every third year. They are harvested in a very crude way, chiefly by Indians, from the remote districts of New Mexico, Utah and California. [Sidenote: Almonds] The almond is a most desirable food. It contains 17 per cent nitrogen, and 54 per cent fat. The flavor is very agreeable, and the nuts, in digestibility, rank next to protoid nuts. They may be substituted for each other in many dietaries. [Sidenote: Pecans]