无生源说
Xenogenesis \Xen`o*gen"e*sis\, n. [Gr. xe`nos a stranger + E. genesis.] (Biol.) (a) Same as {Heterogenesis}. (b) The fancied production of an organism of one kind by an organism of another. --Huxley.
xenogenesis n : the alternation of two or more different forms in the life cycle of a plant or animal [syn: {alternation of generations}, {heterogenesis}]