By composting sulfur, rock phosphate and soil it was found (McLean, 1918) that sulfur is rapidly oxidized to sulfuric acid; the acid acts upon the tricalcium phosphate, converting it into di-and mono-calcium salts. In the absence of a neutralizing agent or, after this agent has all been used up, the sulfuric acid formed, in the presence of an excess of sulfur, accumulates in the medium. On inoculating such composts into proper culture media, we finally succeeded in isolating a small bacterium which is active in the oxidation of the sulfur. A detailed study of the composting of sulfur, of the transformation of the tri-calcium phosphate and of the methods used in the isolation of the organism are found elsewhere (Lipman, Waksman and Joffe, 1921); only a brief review of the process of isolation is presented here. Method of isolation. The following media were originally used for the isolation of the organism: Medium 1:

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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.

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