Abstract

¹⁵N from labelled yeast protein, fed to marasmic and recovered infants, appeared in the stool shortly after administration and continued to be excreted for 100 hours. Unabsorbed dietary ¹⁵N, which appeared with carmine-marked stools, formed only part of this excretion.

Calculations of the endogenous nitrogen content of infant stool agreed closely with those of previous workers.

The use of intravenously injected ¹⁵N showed that part of the stool nitrogen was derived from this source. It was excreted as urea, ammonia, and other compounds, and totalled about 2% of the administered urea.

The persistence of the ¹⁵N in the stool suggests that it had in part been incorporated into cellular material.