Abstract
A new form of virus newly-isolated from mice and considered to belong to the MNI group was treated in present report and several characteristics were described. Although it can be regarded to have characters highly similar with those of the influenza viruses, its hemagglutinating activity is subject to change, being especially conspicuous in its thermofragility. We, therefore, consider those characters to be helpful in analysing the inter-relationship between this form of virus and the influenza viruses.
