Abstract
1. Polymers of orosomucoid were produced in two molecular shapes, filamentous (;chain') and spherical (;ball'), by heating the sodium salt of the monomer in either water or high concentrations of sodium chloride. An ;intermediate' state containing both shapes in various proportions was found in preparations obtained by polymerizing orosomucoid in intermediate concentrations of sodium chloride. 2. The filamentous form of polymer was found to inhibit strongly the haemagglutination of some (;sensitive') strains but not of other (;insensitive') strains of influenza virus; the ;intermediate' form feebly inhibited haemagglutination by ;sensitive' strains. 3. The filamentous form agglutinated both ;sensitive' and ;insensitive' strains of virus; the other forms of polymer did not. It also inhibited multiplication of both ;sensitive' and ;insensitive' strains when inoculated into embryonated and de-embryonated eggs. 4. The ;intermediate' and spherical forms of the polymer had no effect on the virus multiplication. 5. Polymers of orosomucoid from which neuraminic acid had been split off had no detectable effect on influenza viruses.