Abstract
1. The nucleic acid contents of purified and concentrated standard passage particles and undiluted passage (3rd passage) particles of influenza virus were compared.
2. In influenza virus particles the ribonucleic acid content (6.2%) is dominant than that of desoxyribonucleic acid (0.47%)
3. Between the nucleic acid content of these two passages there is no difference as desoxyribonucleic acid is concerned. (In standard passage: 0.47%, in undiluted passage: 0.39%). While, between the content of ribonucleic acid of these two, remarkable divergency is shown: the standard passage virus contains 3.3 times of ribonucleic acid compared with undiluted passage virus. (6.2%: 1.8%)
It is suggested that the infectivity of the virus is closely related to the ribonucleic acid content.
4. In the course of extraction of ribonucleic acid, the nucleic acid of the virus can not be extracted with cold perchloric acid until it is heated to 70°C.
