preformation


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Related to preformation: Preformation theory

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

[-fôrmā′shən]
Etymology: L, prae + formatio, formation
an early theory in embryology in which the organism is contained in minute and complete form within the germ cell and after fertilization grows from microscopic to normal size. Compare epigenesis.

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 ?
As Priestley points out in his Critical Notes to Political Justice, Godwin later appears to reverse his attitude towards preformation in Thoughts on Man, arguing that "every child that is born, has within him a concealed magazine of excellence.
On the other hand, while for most of his career, Kant had been a preformationist, following from the work of Caspar Friedrich Wolff's (1733-1794) Theoria Generationis (1759) and Johan Friedrich Blumenbach's (1752-1840) Institutiones Physiologicae (1787), Kant only gradually came to articulate the superiority of the theory of epigenesis over that of preformation.
Preformation theory required that the motive force for a new being come from either the mother or the father, since the new being was envisioned as already complete.
The cord construction design parameters, such as the number of filaments, the filament diameters, lay lengths and directions, as well as the preformation type and degree are important to determine the cord geometry for good rubber penetration.
Each in turn examined the theory of preformation in the light of natural philosophy and religion.
By observing the instructional lineages across five consecutive, cumulative, and cyclical formation periods (namely, preformation, information, transformation, uniformation, and conformation/reformation/deformation), seven information flows can be quickly sketched and displayed in parallel to show the vertical and horizontal interrelationships of the four twisting-bonding/clipping-jointing subforces that constantly cooccur in the invisible form of the Q-T-S-C Chain.
This tension was inherited from the neo-Kantians: already Cassirer's work, Richardson argues, was marred by the inability to decide between the conception of the synthetic a priori as the relative conventionalist a priori determinations that allow for the formulation of various theories and that of the synthetic a priori as a preformation of any rational thought.
1990), and organ preformation is widespread among angiosperms (Geber et al.
In the United States, such preformation coordination is most often analyzed under section 1 of the Sherman Act.
Preformation of buds may be an evolutionary adaptation to a short growing season.
Primordial Germ Cells in the Invertebrates: From Epigenesis to Preformation.
The history of preformation begins one evening in the middle of the seventeenth century, with an after-dinner party trick.