“…Observations on the utilization by plants of nitrogen in other organic compounds are scattered through the literature. Barley is stated to grow with lysine as its only nitrogen source (Virtanen, Laine & von Hausen, 1936) and uninoculated peas to use the nitrogen of aspartic and glutamic acids in preference to inorganic nitrogen (Virtanen, 1938. Glutamic acid and alanine alone of a series of amino-acids (including aspartic acid and glycine) showed no inhibition of root growth in cress seedlings when supplied at 1000 p.p.m.…”