reality, food has many other offices to fulfill than that of warming the body and of giving it energy—that is to say, of providing for the functional activity of the living machine. It must also serve to provide for wear and tear. The organism needs a suitable quantity of certain fixed principles, organic and mineral. These substances are evidently intended to replace those which have been involved in the cycle of matter, and to reconstitute the organic material. To these materials we may give the name of histogenetic foods (repairing the tissues), or of plastic foods.
§ 5. The Plastic Rôle of Food.
Opinions of the Early Physiologists.—It is from this
point of view that the ancients regarded the rôle of
alimentation. Hippocrates, Aristotle, and Galen
believed in the existence of a unique nutritive substance,
existing in all the infinitely different bodies
that man and the animals utilize for their nourishment.
It was Lavoisier who first had the idea of a
dynamogenic or thermal rôle of foods. Finally, the
general view of these two species of attributes and
their marked distinction is due to J. Liebig, who
called them plastic and dynamogenic foods. In addition
he thought that the same substance should accumulate
the same attributes, and that this was the case with
the albuminoid foods, which were at once plastic and
dynamogenic.
Preponderance of Nitrogenous Foods.—Magendie, in 1836, was the pioneer who introduced in this interminable list of foods the first simple division. He divided them into proteid substances, still called
