The Collaborative International Dictionary
Polygeny
Polygenesis \Pol`y*gen"e*sis\ (-j[e^]n"[-e]*s[i^]s), Polygeny \Po*lyg"e*ny\ (p[-o]*l[i^]j"[-e]*n[y^]), n. [Poly- + genesis, or root of Gr. gi`gnesqai to be born.] (Biol.) The theory that living organisms originate in cells or embryos of different kinds, instead of coming from a single cell; -- opposed to monogenesis.
Wiktionary
polygeny
n. polygenesis.