PROPERTIES OF PNEUMONIA VIRUS OF MICE (PVM) IN RELATION TO ITS STATE.

Additional evidence is presented that PVM is capable of combining firmly with lung tissue particles or erythrocytes from certain susceptible species. Release of the virus from such combination can be effected by treatment with alkali as well as by heating. Free virus expressed from infected lungs without grinding the tissues is infectious and causes hemagglutination when tested directly. The concentration of virus can be estimated more accurately by means of the hemagglutination technique than from the results of infectivity tests in mice. Present evidence indicates that PVM may occur in 4 different states and that in each state it manifests distinctive properties.