(Biol.), alternation of sexual with asexual generation, in which the products of one process differ from those of the other, a form of reproduction common both to animal and vegetable organisms. In the simplest form, the organism arising from sexual generation produces offspiring unlike itself, agamogenetically. These, however, in time acquire reproductive organs, and from their impregnated germs the original parent form is reproduced. In more complicated cases, the first series of organisms produced agamogenetically may give rise to others by a like process, and these in turn to still other generations. Ultimately, however, a generation is formed which develops sexual organs, and the original form is reproduced.
Alternation of generation
. See under Generation.
alternation of generations
noun the alternation of two or more different forms in the life cycle of a plant or animal
noun the larger than expected generation in United States born shortly after World War II
noun a United States youth subculture of the 1950s; rejected possessions or regular work or traditional dress; for communal living and psychedelic drugs and anarchism; favored modern forms of jazz (e.g., bebop)
noun a difference between the views of young people and their parents
noun the generation following the baby boom (especially Americans and Canadians born in the 1960s and 1970s)
noun a hypothetical organic phenomenon by which living organisms are created from nonliving matter
abiogenesis; autogeny; autogenesis.
(Biol.), the fancied production of living organisms without previously existing parents from inorganic matter, or from decomposing organic matter, a notion which at one time had many supporters; abiogenesis.
noun power derived from the wind (as by windmills)