In an attempt to investigate the antigen-antibody relations and the value of immunodiagnosis for several helminths, Ouchterlony tests and immunoelectrophoreses were carried out. Taenia saginata, Cysticercus sp. of cestodes, Clonorchis sinensis, Fasciola hepatica and Paramphistomum sp. of trematodes,and Ascaris suum of nematodes were used as antigens. On the other hand, antisera were obtained by injecting 0.5 ml each of the above antigens and the same amount of complete Freund's adjuvant into rabbits ten times at an interval of one week. The result obtained in this study are as follows: A larger number of precipitin arcs were demonstrated in homologous antigen-antibody reactions than in heterologous antigen-antibody reactions both in Ouchterlony tests and immunoelectrophoreses. Gross reactions were observed between the different species of the same class, but no cross reactions were noticed when the classes were different with one or two exceptions, such as between T. saginata, F. hepatica and A. suum. In A. suum, the difference between the male and female was more distinct in Ouchterlony test and immunoelectrophoresis than in the examination of organs such as genital organ and coeliac fluid. Immunoelectrophoresis revealed specific arcs and higher sensitive reaction than Ouchterlony test, and was considered to be a more valuable method for identifing species and immunological diagnosis.
