Contents: Origin of Metazoa, Platyhelminthes, Parasitic Physiology, Planaria, Growth of Parasites, Reproduction, Transmission of Parasites, Interaction of Animals, Interaction of Plants, Parasitic Immunity, Antibody Production in Parasites, Ecology of Parasites, Living Activities in Trematodes, Living Activities in Cestodes, Cell Biology of Schistosomes, Nematod Control.