The Relation between Sulphur and Nitrogen Metabolism

THE purpose of the present paper was an attempt to elucidate the following controversial points in protein metabolism.1. Is the breakdown of ingested protein immediate or is it spread over several days?2. Is there any difference in the rates at which nitrogen and sulphur are excreted?3. If ingested protein can be retained is it capable of covering the break- down of body protein in the first few days of starvation?4. What is the nature of the stored material?Is ingested protein dealt with immediately?This question was repeatedly investigated by the older workers, but it was not until the introduction of the superimposition method of Falta that clear proof was obtained that a real delay in excretion may take place.Falta [1906] gave a subject a constant diet until nitrogen equilibrium was established and then on one day super- imposed on this diet a known amount of the protein to be investigated.The course of its excretion was then followed for several days.The amount of the protein excreted in each particular day was found by subtracting the total nitrogen output on the basal diet from the nitrogen output on the day con- cerned.He found that the time of excretion varied with different proteins.Hiimiiliiinen and Helme [1907], using this method, found the same delay in the metabolism.The general conclusion is that there is a retention in some form of the nitrogen of the food.Is there any difference in the rate at which the nitrogen and sulphur of the ingested protein is excreted?Feder [1881], by following the outputs of nitrogen and sulphur in 2-hourly samples of the urine of a dog after meat ingestion, found an early excretion of sulphur and a delay in the nitrogen output.He also emphasised the importance of 2-hourly samples as opposed to the 24-hourly collection.Falta [1906] found, taking the 24-hour urine, an early excretion of sulphur after the ingestion of egg white and caseinogen.Hiimalainen and Helme [1907] obtained the same result with egg white, veal and proton (caseinogen).Wolf and Osterberg [1911] maintained that when egg white, either raw or coagulated, was superimposed sulphur was more slowly excreted