Abstract
Nucleic acid was extracted from purified virus preparations of 5 A and 3 B strains. The nucleic acid from each strain was hydrolyzed, and the purine and pyrimidine content determined by chromatographic analysis. The results indicate specific differences in the nucleic acids of A and B strains. The nucleic acid isolated from "incomplete" virus showed on analysis the same proportion of bases as that from standard virus, but the content of nucleic acid was decreased. The experiments reported afford strong evidence for the functional significance of influenza virus nucleic acid.