preformation

American  

[pree-fawr-mey-shuhn] / ˌpri fɔrˈmeɪ ʃən /

noun

1. previous formation.

2. Biology. (formerly) the theory that the individual, with all its parts, preexists in the germ cell and grows from microscopic to normal proportions during embryogenesis (epigenesis ).

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preformation British  

/ ˌpriːfɔːˈmeɪʃən /

noun

1. the act of forming in advance; previous formation

2. biology the theory, now discredited, that an individual develops by simple enlargement of a fully differentiated egg cell Compare epigenesis

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Other Word Forms

• preformationary adjective

Etymology

Origin of preformation

First recorded in 1725–35; pre- + formation

Example Sentences

By the time Buffon sat down to write his own treatise of natural knowledge, the doctrine of preformation was still in vogue, even with most natural philosophers.

From Salon • Jan. 17, 2016

Proponents of preformation could see the evidence all around them in the natural world.

From Salon • Jan. 17, 2016

Those who believed in preformation were never short of evidence.

From Salon • Jan. 17, 2016

The freshwater polyp’s ability to be split into two separate organisms did not, in his mind, fit the notion of preformation.

From Salon • Jan. 17, 2016

The principal challenge to preformation was the idea that something had to happen during embryogenesis that led to the formation of entirely new parts in the embryo.

From "The Gene" by Siddhartha Mukherjee