Abstract: The trichome of the blue-green alge Anabaena azotica was suspended in 0.5mol K₃PO₄, 7% or 36—38% Formalin, 70% or 95%alcohol, glacial acetic acid, or the trichome suspension boiled or passed a autoclave (in 15 pounds for 15 minutes). The treated trichome discoloured immidiarely and became inactive, However, the inactive trichome could move and aggregate to the direction from light irradiation. But in 1mol NaOH or HCl they lost its moving ability. Inactive trichome or cells of Spirulina Platensis, Anabaenopsis elenkini and Anacystis nidulans have also had phototaxis.