Cell wall preparations from ryegrass endosperm cells grown in tissue culture contain polysaccharides composed of glucose, xylose, arabinose and galactose residues. The protein content is very low. The cell wa.ll preparations have been fractionated by successive extraction with water at 40�C, 8 M urea, O�5 M KOH, 4�27 M KOH and 6 M NaOH-O' 81 M H3B03 ? The polysaccharides in the fractions were identified by monosaccharide and methylation analysis, supplemented by the use of a specific fi-glucan hydrolase. The results indicate that the three' main types of polysaccharide present are 1,3: 1,4-fi-glucan, arabinoxylan and/or galacto-arabinoxylan and cellulose.