Histones H2a, H2b, H3, and H4 are present in equimolar amounts in chick erythroblasts.

A quantitative labeling method for stoichiometric analysis has been applied to an investigation of the histone composition of chick erythroblast chromatin. The necessity of long fractionation procedures and the dangers of preferential extraction and staining are eliminated through the use of this simple procedure which involves the direct analysis of nuclear proteins on sodium dodecyl sulfate gels. Only a knowledge of the amino acid compositions of the histones is required. H2a, H2b, H3, and H4 are found to be present in nearly equimolar quantities.