1. A tentative method is described for extracting a labile nucleo-protein from scarlatinal Streptococcus hemolyticus.
2. The product differs chemically and serologically from the fractions prepared by subsequent alkaline extraction of the cell residues, and from protein obtained by the classical method for extraction of bacterial "nucleoproteins."
3. The new nucleoprotein is sensitive to very weak alkalies and readily loses nucleic acid under these conditions. The protein degradation products resemble the alkaline-extracted protein fractions of the cell residues.
4. The bearing of the properties of the new nucleoprotein on the chemistry of nucleoproteins in general is discussed, also the possible relation of the fractions obtained to the analysis of streptococcus antigens made by Lancefield.