AbstractDesoxyribonuleoprotein was isolated from the liver of hog and duck by Mirsky‐Pollister's procedure with some modifications. After refining the extract, a white gel‐like material was obtained. From this material histones and DNA together with non‐histone protein were isolated by treatment with acid followed by fractional precipitation. The histones were hydrolyzed and the hydrolyzate was analyzed by paper‐chromatographical method. In the hydrolyzate, the presence of 16 amino acids (asp., glu., gly., ala., val., leu., ileu., ser., the., met., pro., phe., tyr., his., lys., and arg.) was identified. Among these the presence of 8 amino acids (asp., gly., leu., pro., try., his., lys., and arg.) was proved by comparing their respectiveRfvalues with the authetic samples, while that of the remaining ones merely by noting their respectiveRfvalues. The relative abundance of these amino acids in the histone was also estimated colorimetrically. The results furnish additional evidence in favor of the hypothesis that liver histones might be organ