The theory of generation which holds that the germ is created entirely new, not merely expanded, by the procreative power of the parents
{i} development of an organism from a single undifferentiated cell through a gradual process of cell division and differentiation into organs (Biology); change in the nature of a mineral which is brought about by external forces (Mineralogy)
the theory that an organism develops by differentiation from an unstructured egg rather than by simple enlarging of something preformed