In conclusion it may be said that contrary to the results of the fractionation obtained from the fractionation of cellulose xanthate diethylacetamide by Fink, Stahn, and Matthes; the results obtained here indicate that there is a definite variation of the degree of substitution from fraction to fraction. And that therefore cellulose xanthate as commercially prepared is heterogeneous with respect to degree of polymerization and degree of substitution. There does seem to be a definite relationship of some sort between the two factors, the degrees of polymerization and substitution. Fractionation as accomplished here is controlled by both the degree of polymerization and the degree of substitution and at no time is it likely that either factor is independent of the other. In fact, there is a strong probability that the degrees of polymerization determined are only apparent degrees of polymerizations controlled by the variations in substitution. It is known that the viscosity of compound in solution is a function of the degree of substitution; to what extent is unknown. / M.S.