Electron Microscopic Observation of Symbiotic Relationship between Azolla and Anabaena During the Formation of Azolla Sporocarp Studies on Photosynthetic Membrane and Its Characterization in Anabaena azollae 黄进华 Electron Microscopic Observation of Symbiotic Relationship Between Azolla and Anabaena During the Megaspore Germination and the Sporeling Development of Azolla RELATIVE HEAT TOLERANCE OF ANABAENA AZOLLAEMEASURED BY THE CHLOROPHYLL-FLUORESCENCE METHOD