Preformism

Preformism is the doctrine of the presence in the embryo or egg of already formed organisms (or parts) of a subsequently developing organism. The term was introduced in 1893 by the American biologist Ernst Haeckel. Preformationists associate pre-existence with the concept of generation in their opinion, a living cell arises directly from nonliving matter. Teleologically inclined theologians (Presbyterian) understood it as the economy of God's providence, a sign of the Divine plan in nature. According to the teachings of preformationists, an adult organism is obtained by development from an initially or completely already created organism, which is present or embedded in it.

Despite the fact that preformation or premorphism has been proven and reproducible in the embryonic development of animals and plants for several centuries, some scientific concepts of the 19th century rejected this teaching or did not recognize it.

Preformationism is considered discredited among evolutionary biologists and anatomists due to disagreements among various studies. Despite the fact that the classic arguments about the preformationist era - the repetition of the same type from generation to generation - continue to be common in pedagogical practice, this is no longer recognized as a strict conclusion of science. In contrast, major paleoecologists such as Allan Quenty and Paul Selser recognize the important role of repetition. This can help scientists explain the existence of an organism's structural form before the organism's survival. The statement that species repeat rather than change from generation to generation corresponds to a certain scientific understanding of the development of life.