From Big Medical Encyclopedia

INDIVIDUAL — elementary unit of life. The lake it is indivisible without loss of properties lives (see). For most of the highest cross razmno-zhayushchikhsya the organisms not capable to vegetative reproduction, delimitation of O. does not cause difficulties. At the same time there are many cases when unambiguously it is impossible to use the concept «individual».

With morfol, the points of view of O. it is characterized by differentiation on the coordinated structures — bodies, fabrics (for multicellular), organellas (for one-celled). For not colonial protozoa the concept «individual» matches the concept «cell».

In colonies of coral polyps, pearlworts separate O. take strictly certain place, division of functions of the individuals forming uniform colony is observed. At colonial coelenterates a sifo-nofor different O. are characterized by sharp division of functions, different O.' morphology is sharply various, morphological O.'s exarticulation from colony leads to loss of properties of life by it. For tape-worms separate joints strobiles can, with morfol, the points of view to be considered as independent O. at one stages of development of a worm, but are only members of uniform «superorganism» at other stages of individual life.

The higher plants capable to vegetative reproduction, and also the metazoans capable to reproduction by budding (hydra), being morphologically persons, from the genetic point of view are identical and therefore can be considered as one O. Eto treats also any klonalno to the breeding organisms. However from the evolutionary point of view such genetically identical organisms can appear under the influence of different selective factors; it is necessary to read out all morpho-physiological units which came from one zygote or a gamete, napr in a case from these positions O. parthenogenesis (see), or from one disputes or a kidney (at vegetative reproduction), to-rye can individually be affected from these or those environmental factors.

At impossibility of unambiguous definition of O. specially specify in what sense (morphological, genetic or evolutionary) the concept «individual» of this specific case is used.

See also Organism , Theory of evolution .

Bibliography: 3ussman M. Developmental biology, the lane with English, M., 1977; Timofeev-Resovsky N. V., Baneberries of H. N and Yablokov A. V. Short sketch of the theory of evolution, M., 1969; Ehrlich P. and Holm R. Process of evolution, the lane with English, M., 1966.

H. N. Vorontsov.