Nuclein Metabolism in a Dog with Eck's Fistula

All nitrogenous substances completely metabolized in the organism of mammals are removed by the urine in form of urea. Every other nitrogenous constituent of the urine is either a substance which has for one reason or another escaped its final transformation, or has not been metabolized by the organism at all. Under metabolism here, of course, is understood a set of chemical reactions which result, first, in maintenance of the integrity of the body's tissue and, second, in supplying it with calories sufficient to perform all the functions of the organism. The quantity of nitrogen metabolized by the organism for the purpose of energy production is regulated primarily by the intake of nitrogenous foodstuffs , and by the quantity of reserve protein deposited in the organism. The quantity of nitrogen metabolized as a result of tissue deterioration for the purpose of maintaining its integrity is determined by the mass of the cells in the organism, by the amount of work which the tissues are called upon to perform, and by the intensity of the effort employed by the organism in performing the work. Thus, work of short duration, but of such intensity as would occasion a state of fatigue, brings about greater tissue deterioration than prolonged work of lower intensity. Under normal conditions there exists a definite proportion between the two phases of nitrogenous metabolism, namely, between metabolism of nitrogenous foodstuffs of reserve protein on the one hand, and metabolism of cellular protein on the other. This proportion changes with the change of the plane of nutrition of the organism and with change of the quantity of protein in the food. However, conditions are conceivable in which it is made possible that the organism may be supplied with a sufficient amount of 229