1. Wiffen, R. D., and Heard, M. J., Nature, 224, 715 (1969).
2. Tulloch, G. S., and Shapiro, J. E., Bull. Brooklyn Entomol. Soc., 48, 57 (1953).
3. Day, M. F., and Briggs, M., J. Ultrastruct. Res., 2, 239 (1958).
4. Smith, D. S., and Littau, V. C., J. Biophys. Biochem. Cytol., 8, 103 (1960).
5. Storey, H. H., and Nichols, R. F. W., Proc. Roy. Ent. Soc. Lond., 12, 149 (1937).