I. the Development of Mumps Virus Hemolysin and Its Inactiva- Tion by Certain Physical and Chemical Agents

Certa in propert ies of a hemolysin associated with mumps virus have been described in a previous repor t (1). The labile na ture of this hemolyt ic principle was indicated b y its inact iva t ion b y hea t and b y its deter iorat ion during storage under a va r ie ty of conditons. In order to faci l i tate fur ther invest igat ion of this v i ra l hemolysin, i t was necessary to determine the condit ions for growth of mumps virus in embryona ted eggs which would provide infected, ex t ra-embryonic fluids wi th maximal hemolyt ic ac t iv i ty and, to ascertain the s tab i l i ty of the hemolysin under a va r ie ty of conditions. In this connection, the effects of certain physical and chemical agents on the hemolytic, hemagglut inat ive, and infective capacit ies of the virus were studied. These experiments would appear not only to indicate the s tab i l i ty of these three propert ies under a va r i e ty of conditions, bu t also by establishing the relat ive sensi t ivi ty of each to a given agent, m a y indicate certain relationships between them. As used here, the term "hemolys in" indicates a virus part icle containing mater ial which produces hemolysis, wi thout any implicat ion tha t the act ive factor is a separable product ra ther than a const i tuent of the virus part icle itself.