In geology, epigenesis means changes in the mineral composition of a rock because of outside influences, e.g. the injection of a vein of ore into existing rock.
In biology, epigenesis has at least two distinct meanings:
- the unfolding development of an organism, and in particular the development of a plant or animal from an egg or spore through a sequence of steps in which cells differentiate and organs form;
- the theory that plants and animals develop in this way, in contrast to theories of preformation.
