Alternate generation

(Biol.)

See under Generation.

(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.

alternate generation

generation

[jen″er-a´shun] 1. the process of reproduction.2. a class composed of all individuals removed by the same number of successive ancestors from a common predecessor, or occupying positions on the same level in a genealogical (pedigree) chart.alternate generation reproduction by alternate asexual and sexual means in an animal or plant species.asexual generation (direct generation) production of a new organism not originating from union of gametes.first filial generation the first-generation offspring of two parents; symbol F₁.parental generation the generation with which a particular genetic study is begun; symbol P₁.second filial generation all of the offspring produced by two individuals of the first filial generation; symbol F₂.sexual generation production of a new organism from the cell formed by the union of a male gamete (spermatozoon) and a female gamete (oocyte).spontaneous generation the discredited concept of continuous generation of living organisms from nonliving matter.