It has been said many times (and that includes prefaces to previous
volumes in this series) that the rise of molecular biology has opened up
the exciting possibility of a deeper understanding of developmental
biology. The central dogma has transformed genetics and now there is a
great rush to have it transform development. Buk in the heat of the
moment I sometimes wonder whether we might forget what are the main
problems. Perhaps it would be fairer to say, that we tend to forget many
of the main problems, for certainly one of the greatest among them is
gene action, and every bit of effort that has been concentrated on its
molecular mechanisms has been of immense importance. However, with￾out detracting from the crucial significance of the problem of gene action
it should be reiterated that it is not the whole problem of development,
but only a part of it (see Lederberg, 1966; Grobstein 1969; Monroy,
1970)