a. [a. Fr. épigène, ad. Gr. ἐπιγενής, f. ἐπί upon, after + -γενής born, originating.
The Gr. word occurs with sense ‘arising subsequently (to birth),’ said of a disease, in opposition to ‘congenital.’ This use seems to be the source of sense 1; in sense 2 the prefix is taken as = ‘upon,’ ‘above.’]
1. Crystallogr. See quot. 1823. By some writers used for pseudomorphous.
1823. H. J. Brooke, Introd. Crystallogr., 93. To one class of these [crystals] the Abbé Haūy has applied the name of Epigene, where a chemical alteration has taken place in the substance of the crystal subsequently to its formation.
1851. Ruskin, Stones Ven. (1874), I. 2nd Pref. p. xiii. The epigene crystal, formed by materials of one substance modelled on the perished crystals of another.
2. Geol. Produced on the surface of the earth: opposed to hypogene.
1880. Geikie, in Nature, XXIII. No. 575. 4/2. The whole epigene army of destructive agencies, air, rain, frost [etc.]. Ibid. (1882), Text-bk. Geol., III. I. 196. Epigene or Surface Action—the changes produced on the superficial parts of the earth. Ibid., III. II. 316. The word epigene may be suggested as … antithetical to hypogene.
