Laboratory experiments have shown that C.demersum inhibited the growth of algae Chlorella vugaris and Scancdesmus obliguus. In culturing algae with C.demersum or the medium in which C.demerusm have grown already, the algae growth is inhibited.Alkaloids extracted from a medium in which C.demersum have been cult-ued were found to have an irhibitive effect on the growth of S.obliquus and the effect is larger than that of original medium. The boiled medium is still more inhibited than the unboiled. This may be ...