Biol. [f. Gr. ἐπί upon + γένεσις generation. See GENESIS.] 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 ‘emboitement.’]
1807. Edin. Rev., XI. 81. The Epigenesis … is what most physiologists now assume as the only true theory of generation.
1831. Blackw. Mag., XXIX. 68. The two styles of conversation corresponded to the two theories of generation—one (Johnson’s) to the theory of Preformation (or Evolution)—the other (Burke’s) to the theory of Epigenesis.
1847. Lewes, Hist. Philos. (1867), Proleg. § 3. With Mind, as with Body, there is not preformation or pre-existence, but evolution and epigenesis.
1879. trans. Haeckel’s Evol. Man, I. ii. 40. Caspar Friedrich Wolff … with his new Theory of Epigenesis gave the death-blow to the entire Theory of Preformation.
Hence Epigenesist, one who holds the theory of epigenesis.
1816. Keith, Phys. Bot., II. 364. This is the theory of the epigenesists.
