Milder conditions of hydrolysis than have been heretofore generally used to characterize cellulosic structures chemically were employed for the purpose of comparing the hydrolytic accessibility of native and regenerated structures, respectively. It is assumed that the acces sibility of the fine cellulosic structure is related to the rate of drop of the average degree of polymerization of the cellulose with time of treatment. Using 5 N HCl at 18°C, the following samples of cellulose were evaluated: - 1. Cotton linters and acid-pretreated cotton linters, respectively, before and after non- degradative solution and regeneration. 2. Cotton linters and acid-pretreated cotton linters, respectively, before and after swelling in 18-percent NaOH at 18°C. 3. Viscose rayons made from cotton linters and acid-pretreated cotton linters, respectively.