Abstract
This paper describes an investigation into the degree of homogeneity of the substance termed collocalia mucoid obtained from edible bird nest. This material is a potent inhibitor of influenza virus haemagglutination, and additional information is given here regarding its ability to neutralize infectivity. The crude material obtained by simple extraction was found to contain three components differing in molecular size and biological activity. Some separation of these was obtained by means of preparative ultracentrifugation. The slowest moving component differed from the others not only physically but also in having much less inhibitor activity.