ON account of the fact that some of the xylan in straws and hardwoods remained in the α-cellulose, Hawley and Norman1 considered it to be intimately associated with the α-cellulose. According to Astbury, Preston and Norman2, this association corresponds to the relationship between the components of a solid solution or a mixed crystal. Norman3 regards xylan as an integral part of the cellulosic aggregate, oriented in the same way as true cellulose and taking part in the micelle. This view received support from the fact that xylan-free α-cellulose could not be obtained from many sources4; some celluloses failed to part with their xylan even on boiling with 10 per cent sodium hydroxide5. Chemical combination between xylan and α-cellulose has therefore been suggested.