Abstract
A combination of ether and phenol treatment of cells infected with an Asian strain of influenza virus was a more efficient method for isolating infectious ribonucleic acid than was treatment with phenol alone. The phenol extracted material possesses many of the properties of nucleic acid as measured by physical and chemical means. Virus yielded by an RNA-infection grows in chick kidney cells to a much lower titer than the original strain and must be passaged amniotically before it will grow in the allantoic cavity of embryonate eggs. The antigenic characteristics of the RNA-derived virus are indistinguishable from those of the parent virus.