preformation

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pre·for·ma·tion the·o·ry

archaic theory that the embryo was fully formed in miniature within a gamete at the time of conception.
See also: homunculus. Compare: epigenesis.

preformation

(prē′fôr-mā′shən)
n.
1. The act of shaping or forming in advance; prior formation.
2. A theory popular in the 1700s that all parts of an organism exist completely formed in the germ cell and develop only by increasing in size.

preformation

(prē-fawr-mā′shŭn)
In embryology, the development of structures from pre-existing templates, e.g., of bones from cartilage templates.
References in periodicals archive ?
Reva Siegel's foundational work on abortion restrictions in the United States highlights the preformationist views on which the nineteenth-century anti-abortion movement was based.
"(112) A zygote is "internally activated"--i.e., the genetic blueprint itself, rather than the gestational process, triggers development--and the genome itself "assumes control of the whole morphogenetic process from the beginning of embryonic development." (113) These claims are radically preformationist. According to Lugosi, the zygote proceeds to "execute a plan" that is best carried out "[u]ndisturbed by external intervention....
Moreover, the preformationist framing of the debate sets the terms of discussion even for those who accept Roe's terminology of "potential life." The prevailing legal analysis of artificial wombs, including among those who support the right to abortion today, is that they will eliminate both the need and the justification for abortion rights.
The premise is thus that a woman seeking an abortion has an inherent conflict of interest with the embryo, a premise that is based on the preformationist ideology of reproduction.
In the world of surrogacy, for example, "the woman gives the baby 'back to the father,' as if it came from him in the first place" in the classic preformationist sense.
Hailer himself started as a preformationist, briefly converted to epigenesist, and ended his life a staunch defender of preformation.
(7) But to a large extent, it is fair to say that environmental economics is still preformationist in what it can contribute to regulatory analysis.
This last insight was undoubtedly a relief to the preformationists. For looming over most of seventeenth-century Europe was the specter of an omnipotent God.
Of course, there is no getting around the fact that the preformationists were wrong--or mostly.