1. GERLING, D. and T. ORION (1973) J. Invertebr. Pathol. 21: 164-171.
2. HASHIMOTO, K. and H. KITANO (1971) Zool. Mag. 80: 323-329 (in Japanese with an English abstract).
3. JACKSON, D. J. (1924) Nature 113: 353-354.
4. JACKSON, D. J. (1928) Proc. Zool. Soc. London 1928: 597-630.
5. JUNNIKKALA, E. (1966) Ann. Acad. Sci. Fenn. Ser. A IV Biol. 100: 1-83.