Hemolymph smears were prepared after extruding soft tissues of Oncomelania hupensis and stained by fluorescent dye acridine orange. The hemocytes were observed under a fluorescence microscope. The following 12 types of hemocytes were clearly seen, including round hemocytes with abundance of red cytoplasm, round hemocytes with abundance of red cytoplasm and intracellular granules, round hemocytes with little red cytoplasm, round hemo-cytes with little red cytoplasm but the presence of intracellular granules,...