1) Alternation of generations 2) Heterogenesis 3) Metagenesis 4) Xenogenesis 1) Metagenesis 
• (n.) The faculty of multiplying in two ways; -- by ova fecundated by spermatic fluid, and asexually, as by buds. See Parthenogenesis.
Di·gen'e·sis noun [ Prefix di- + genesis .] (Biol.) The faculty of multiplying in two ways; -- by ova fecundated by spermatic fluid, and asexually, as by buds. See Parthenogenesis . 
Type: Term Pronunciation: dī-jen′ĕ-sis Definitions: 1. Reproduction in distinctive patterns in alternate generations, as seen in the nonsexual (invertebrate) and the sexual (vertebrate) cycles of digenetic trematode parasites.