p. 91 - 94 PRESENCE DE PYTHIUM SP. SUR L'ALGUE PORPHYRA LEUCOSTICTA Mukader Mujdaba-Apas Institut Roumain de Recherches Marines Constanta Abstract The parasiting of the mature alga Porphyra leucostica THUR., collected during the spring of 1974 from submerged rocks at the depth of 20 cm, by the Phycomycet Pythium sp. PRINGSHEIM, is pointed out.