Page:Popular Science Monthly Volume 5.djvu/610

592 and mental development by the food they take, than the individuals of whom that sum is made up? This seems to be the decision of history. Philosophers (even the great thinker of Königsberg himself) have not a word to say about the influence on human races and peoples of different food-supplies. The world heard at first with astonishment the saying of a famous scientific man, that, "could man live on air and water alone, such notions as master and servant, prince and subject, friend and foe, hate and love, virtue and vice, right and wrong, etc., would have no existence, and political communities, social and family life, human intercourse, commerce, trade, and industry, art and science—in a word, whatever makes man what he is—depend entirely on the fact that man possesses a stomach and is subject to a law of Nature which compels him daily to take a certain amount of food."

As we start out with the principle, too late recognized in historical research, that the selection of articles of food is not only important for the personal well-being of the individual, but that it is a weighty, world-stirring question for countries and nations in its bearings on the history of civilization, we will, therefore, endeavor to look closely into it, and study the mode in which this influence is exerted.

If nations are to flourish, they, no less than individuals, need wholesome, strong food. The only question is, How are we to determine what food is strong and wholesome? Foods have been classed in different groups, according to the influence they have on the body, in virtue of their essential constituents; and though this classification, like every artificial classification we make in Nature, is only approximately correct, still it gives us some ground to stand on. Blood-formers, or albuminates, are those albuminous materials which constitute the nutritive elements of the blood, and enter into the composition of the muscles, bones, sinews, and ligaments, on which the exercise of force specially depends. The heat-producers or respiratory foods are those rich in carbon; these specially serve to support, with the aid of inspired oxygen, the process of combustion so necessary for the purposes of the organism. Finally, there is a third group of nutritious substances—the nutritive salts—which are of an inorganic nature, and which, after combustion of the food, remain in the shape of ash.

All these food-materials are essential, since with them the organism is built up. Life is an unceasing process of waste and repair, and the food must make good the loss the organism suffers every instant. Even those substances which are contained in the living body only in small quantities must be supplied, for on this depends the activity of important organs. Such substances are common salt, potash, lime, magnesia, phosphoric acid, and, above all, iron, without which the blood-corpuscles would lose their vitality. But none of these groups is, by itself, sufficient for nutrition; they must all be