ALTHOUGH the characteristic features of the chemistry of starch and cellulose are satisfactorily represented by the commonly accepted structures involving chains of glucopyranosido residues, which are unbranched in cellulose and amylose, but branched in amylopectin, certain difficulties remain to be explained. These include, for example, the exact nature of the relationship between the amylose and the amylopectin components of the starches, and the reasons for the different behaviour of cellulose on methylation in the presence and in the absence of oxygen respectively.