1. Brown, D. D., and Dawid, I. B., Science, 160, 272 (1968).
2. Davidson, E., and Hough, B. R., J. molec. Biol., 56, 491 (1971).
3. Davidson, E. H., in Oogenesis (edit. by Biggers, J. D., and Schuetz, A. W.), 129 (University Park Press, Baltimore, 1972).
4. Woodland, H. R., and Graham, C. F., 221, 327 (1969).
5. Piko, L., Devl Biol., 21, 257 (1970).