PREFORMATION (from Lat. pralormare, to shape beforehand, from pea', before + formare, to shape, from forma, shape). A view originating in the seventeenth century with Malpighi and Bonnit. They assumed that the germs of all coming generations were contained in one prim ordial egg. According to this view all the parts and organs of the chick are present in the germ or egg, there being no differentiation, but only an unfolding of parts (`evolutio') existing, infinitesimal in size, in the egg. Haller emphati cally stated that there was no such thing as the differentiation of parts, that no part of the body was made before another, but that all the organs were simultaneously created. It logically fol lowed that the germ destined to give origin to the animal—the ovum according to oculists, the sperm as claimed by the spermatists (q.v.) contained within itself the germ of the next generation, that of the next after, and so on in definitely, so that the first created male or female of each species contained within its sperms or ova the germs of all future generations, inclosed within one another, like a nest of Chinese boxes. The theory of incasement (emboitement)
propounded by Swammerdam in 1733 was that the form of the larva, pupa, and imago of the butter fly prexisted in the egg, and even in the ovary; and that the insects in these stages were distinct animals, contained one inside of the other. This explanation Swammerdam extended to the entire animal kingdom.
Consult, for recent statements, Delage,La struc ture des protoplas»za et les thc'ories cur Pherc% dile (Paris, 1S95) ; Parker and Haswell, Text book of Zoology (New York, 1897) ; Packard, Text-book of Entomology (New York, 1898).