if[1- 14C] Glycollate metabolism and serine biosynthesis in soybean plants [1- 14C] Glycollate metabolism was examined in leafy shoots of soybean plants ( Glycine max) (L.) Merr., var. Adepta). Only small amounts of 14C were incorporated into evolved carbon dioxide and glucidic compounds. Free and protein glycine was labelled but higher levels of radioactivity were found in free serine. Changes in the distribution of 14C with time showed that metabolic conversion glycollate→glycine→serine occured very early and serine biosynthesis was more important in the shoot than in the leaves. Carbon dioxide labelling was always slight compared to serine labelling. These data suggest strong relations between glycollate and nitrogen metabolism.