Further, there is reason in the question whether the continual carrying of excessive amounts of nitrogen reserves in the shape of soluble proteid in the blood and lymph, and in the meshes of tissue and cell protoplasm, is advantageous for the maintenance of the highest degree of efficiency? We all recognize that an excessive accumulation of fat is distinctly disadvantageous to the welfare of the body, and there is, physiologically speaking, equally good ground for considering that the storage of unorganized proteid in amounts beyond all possible requirements of the body may be equally undesirable. Because less tangible to the eye, the accumulation of unnecessary proteid is not so easily recognizable, but this fact does not diminish the possible danger which such accumulation may constitute. It must be granted, however, that we are dealing here with hypotheses and not facts, but though hypothetical the suggestions made are of sufficient moment to merit attention and experimental study. In a later chapter, we shall have occasion to present some facts bearing on these questions. In the meantime, we may lay due stress upon the significance of these views regarding proteid katabolism. We must accept as settled the general idea that there are two distinct forms of proteid katabolism within the body; one form representing the decay of tissue or cell protoplasm, small in amount, with its own particular decomposition products, and absolutely essential for the continuance of life. The other form, the so-called exogenous katabolism, runs a totally different course with distinctive side-products and end-products; it is variable in extent, in harmony with variations in proteid intake, and subject to the suspicion that at the level ordinarily maintained it constitutes a menace to the preservation of that high degree of efficiency which is an attribute of good health. CHAPTER V DIETARY HABITS AND TRUE FOOD REQUIREMENTS TOPICS: Dietetic customs of mankind. Origin of dietary standards. True food requirements. Arguments based on custom and habit. Relationship between food consumption and prosperity. Erroneous ideas regarding nutrition. Commercial success and national wealth not the result of liberal dietary habits. Instinct and craving not wise guides to follow in choice and quantity of food. Physiological requirements and dietary standards not to be based on habits and cravings. Old-time views regarding temperate use of food. The sayings of Thomas Cogan. The teachings of Cornaro. Experimental results obtained by various physiologists. Work of the writer on true proteid requirements. Studies with professional men. Nitrogen equilibrium with small amounts of food. Sample dietaries. Simplicity in diet. Nitrogen requirement per kilogram of body-weight. Fuel value of the daily food. Experiments with university athletes. Nitrogen balance and food consumption. Sample dietaries. Adequacy of a simple diet.