The only qualitative difference in lipid content between dark-grown and green callus was the absence of sulpholipid in dark-grown callus. Phosphatidyl glycerol was the only phospholipid to increase in illuminated dark-grown callus. The glycolipid content of callus increased with exposure to light and was associated with chloroplast development. Sulpholipid was not detected by chemical techniques until just before the onset of chlorophyll synthesis. Subsequently a close relationship was observed between chlorophyll and sulpholipid content.