Abstract
Lyophilized erythrocyte stroma were extracted with chloroform methanol, and a fraction with blood‐group P1 activity was obtained by chromatography on columns of silicic acid followed by preparative thin‐layer chromatography. The active fraction contained at least two glycosphingolipids, and it is concluded, tentatively, that the erythrocyte P1 antigen is a glycosphingolipid.