It is also worth quoting this adumbration of the definition given there (viz., "The formation of an organic germ as a new product"): theory of epigenesis: the theory that the germ is brought into existence (by successive accretions), and not merely developed, in the process of reproduction. ... The opposite theory was formerly known as the 'theory of evolution'; to avoid the ambiguity of this name, it is now spoken of chiefly as the 'theory of preformation', sometimes as that of 'encasement' or 'emboîtement'. ↑ Callebaut, Marc, 2008: Historical evolution of preformistic versus neoformistic epigenetic thinking in embryology. Belgian Journal of Zoology 138(1): 20-35.