(1):

(n.) The change of form which one animal species undergoes in a series of successively produced individuals, extending from the one developed from the ovum to the final perfected individual. Hence, metagenesis involves the production of sexual individuals by nonsexual means, either directly or through intervening sexless generations. Opposed to monogenesis. See Alternate generation, under Generation.

(2):

(n.) Alternation of sexual and asexual or gemmiparous generations; - in distinction from heterogamy.