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D-Galacto-D-xylo-D-glucans (amyloids) from Balsamina, Tropaeolum, and Tamarindus seeds behave in a similar manner in the presence of various glycosidase preparations: slow depolymerization by enzymes from several germinated or non-germinated seeds, and hydrolysis into monosaccharides and oligosaccharides by commercial cellulase and hemicellulase preparations from fungi. A purified cellulase from Penicillium notatum gave a dialyzable fraction almost exclusively composed of alpha-D-xylopyranosyl-(1 leads to 6)-D-glucose residues and a nondialyzable fraction composed of chains of beta-D-(1 leads to 4) [With some (1 leads to 3)]-glucopyranosyl residues; beta-D-galactopyranosyl-(1 leads to 2)-alpha-D-xylosyl groups are linked to some of the beta-D-glucosyl residues at O-6. The presence of (1 leads to 3)-linkages in the D-glucan chain of the Balsamina was verified by methylation and sequential periodate oxidation-borohydride reduction; the distribution of the substituents on the D-glucan chain is not regular. The main D-glucan backbone, where the beta-D-glucosyl residues are partly linked at O-6 to beta-D-galactosyl-(1 leads to 2)-D-xylosyl groups, is linked to D-glucan chains where almost all the D-glucose units are linked at O-6 by one alpha-D-xylosyl group. The presence of 3,6-di-O-methyl-D-glucose after permethylation and hydrolysis suggests that the xyloglucan chains are linked to O-2 of the D-glucosyl units of the galactoxyloglucan backbone.