Around the middle of the eighteenth century, a new interpretation of the origin of organic life arose and began to replace preformation theories: the doctrine of epigenesis. Defenders of preformation theories claimed that the origin of an organism is explained by a divine preformed germ, which-like a russian doll-contains in miniature all features of the prospective living being. Different preformation theorists held differentv i e w so nt h en a t u r eo ft h ed i v i n ep r e f o r m e dg e r m :o v i s t sb e l i e v e d the female egg to be the germ; animalculists, in contrast, the male sperm. Advocates of ovistic theories in the sixteenth and seventeenth centuries were William Harvey (1578 -1657)-who at the same time was an eclectic Aristotelian and early defender of epigenesis-Marcellus Malpighi (1628

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Was Aristotle the 'father' and founder of the epigenesis doctrine? Historically, I will argue, this question must be answered with 'no'. Aristotle did not initiate and had no access to a debate that described itself in terms of 'epigenesis' and 'preformation', and thus cannot be considered the 'father' or founder of the epigenesis-preformation controversy in a literal sense. But many ancient accounts of reproduction and embryological development contain analogies to what early modern scientist called 'epigenesis' and 'preformation', and, in this analogous sense, Aristotle can be considered a precursor of the epigenesis-preformation controversy. But is Aristotle's position actually epigenetic (in this analogous sense), as most of the traditional interpreters hold, or preformationist, as some of the recent scholars believe? I will argue against the one-sidedness of both readings that Aristotle's account of reproduction and heredity contains mainly epigenetic, but also a few preformationist characteristics. Whereas, for instance, Aristotle's idea of a successive development of the embryo's parts is doubtlessly epigenetic, Aristotle's idea that the development of the embryo is an actualization and enlargement of potential parts, which are simultaneously present in the semen, can be considered a preformationist feature.

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