It is of course understood that there can be no fixed dietary standard suitable for all people, ages, and conditions of life. Dietary standards at the best are merely an approximate indication of the amounts of food needed by the body, but these needs are obviously changeable, varying with the degree of activity of the body, especially the amount of physical work performed, to say nothing of differences in body-weight, sex, etc. Further, it is doubtless true that there is what may be called a specific coefficient of nutrition characteristic of the individual, a kind of personal idiosyncrasy which exercises in some degree a modifying influence upon the character and extent of the changes going on in the body. Still, with due recognition of the general influence exerted by these various factors the main question remains, viz., how far the usually accepted standards of diet are correct; or, in other words, is there any real scientific ground for the assumption that the average individual doing an average amount of work requires any such quantity of proteid, or of total nutrients, as the ordinary dietetic standards call for? Cannot all the real physiological needs of the body be met by a greatly reduced proteid intake, with establishment of continued nitrogenous equilibrium on a far smaller amount of proteid food than the ordinary dietary standards call for, and with actual gain to the body? Just here we may emphasize why prominence is given to the establishment of _nitrogenous_ equilibrium, and why the proteid intake assumes a greater importance than the daily amounts of fat and carbohydrate consumed. Fats and carbohydrates when oxidized in the body are ultimately burned to simple gaseous products, viz., carbonic acid and water. Hence, these waste products are easily and quickly eliminated and cannot exercise much deleterious influence even when formed in excess. To be sure, there is waste of energy in digesting, absorbing, and oxidizing the fats and carbohydrates when they are taken in excessive amounts. Once introduced into the alimentary canal they must be digested, otherwise they will clog the intestine or undergo fermentation, and so cause trouble. Further, when absorbed they may be transformed into fat and deposited in the various tissues and organs of the body; a process desirable up to a certain point, but undesirable when such accumulation renders the body gross and unwieldy. With proteid foods, on the other hand, the story is quite different. These substances, when oxidized, yield a row of crystalline nitrogenous products which ultimately pass out of the body through the kidneys. Prior to their excretion, however, these products—frequently spoken of as toxins—float about through the body and may exercise more or less of a deleterious influence upon the system, or, being temporarily deposited, may exert some specific or local influence that calls for their speedy removal. Hence, the importance of restricting