NOUN
- a theory (popular in the 18th century and now discredited) that an individual develops by simple enlargement of a tiny fully formed organism (a homunculus) that exists in the germ cell
How To Use preformation In A Sentence
- Each in turn examined the theory of preformation in the light of natural philosophy and religion.
- The early nineteenth century saw major developments in embryology, which challenged the mechanical concept of generation and overthrew the preformation theory.
- Yet other preformationists believed that the sperm contained the embryo and some even claimed to be able to see a tiny human - a homunculus - in the head of each human sperm.
- Generation and growth were on his view, mechanical processes, for, according to the doctrine of preformation, which he shared with Malebranche, generation is just growth. Kant and Leibniz
- Yet typically discussions of epigenesis and preformation have focused on individual organisms and their development rather than on species. Epigenesis and Preformationism
- In the first chapter, ‘Genesis of the gene,’ Moss traces the emergence of the modern conception of the gene back to the 18th century debate between preformationists and epigeneticists.
- In the caricatured version, preformationism has usually been ridiculed as the belief that a perfect homunculus lies within each sperm or egg cell.
- Yet their experiments ultimately led to new approaches and revised interpretations of what was at issue with epigenesist and preformationist accounts of development. Epigenesis and Preformationism
- The organogenetic event which initiated the neoformed organs continued until early autumn, giving rise to the following year's preformation.
- Development could not therefore be based on preformation but must be epigenetic, because during development many new cells are generated by division from the egg, and new types of cell are formed.
