organism

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organism

any living biological entity, such as an animal, plant, fungus, or bacterium

Organism

 

any living being.

Unicellular and multicellular organisms are distinguished from nonliving matter by several basic vital properties: cellular organization (seeCELL); metabolism, by which proteins and nucleic acids regenerate the organism and maintain a constant internal environment (see, HOMEOSTASIS); movement in all its specific forms—muscular, cytoplasmic, ciliary, and flagellar (seeMOVEMENT); excitability; growth and development; reproduction; variability and heredity (seeVARIATION); and adaptability (seeADAPTATION). Prokaryotes are organisms that lack chromosomes and a typical cell nucleus; examples are bacteria, blue-green algae, Rickettsia, and members of the order Mycoplasmatales. Prokaryotes are simpler in structure and smaller in size than the smallest cellular organisms; for example, the diameter of an animal cell is more than 3 microns (μ), while that of a bacterial cell is usually less than 3 μ. One of the smallest bacteria consists of a total of 5 × 107 atoms once its water is removed.

In its interaction with the environment, an organism is coordinated on the cytoplasmic, cellular, tissular, organic, and organismic levels so as to act as a unified system. The formation of a complete organism in phylogeny consists in the differentiation and integration of cells, tissues, organs, and functions (seeDIFFERENTIATION, INTEGRATION). In unicellular organisms vital functions are effected by special organelles. Over the course of evolution, the development of multicellularity permitted the progressive morphophysiological complexification and differentiation of organisms. This complexification and differentiation is made possible by the structural and functional coordination of cells, tissues, and organs, which is achieved through nervous and humoral means.

The interdependence of organs over the course of animal evolution was comprehensively studied by A. N. Severtsov and students of his school. The phylogenetic aspects of the evolution and differentiation of tissues that arose from cells with common structures, functions, and developmental courses were studied by A. A. Zavarzin, N. G. Khlopin, and A. V. Rumiantsev and their students. The differentiation and integration of organs and functions were also studied by many other Russian and Soviet scientists, including I. I. Mechnikov, I. P. Pavlov, I. I. Shmal’gauzen, and V. A. Dogel’, as well as by foreign scientists, including E. Haeckel, A. Dohrn, and G. de Beer.

Modern biology, especially genetics, has elucidated the genetic connection between generations of organisms and the connections between phylogeny and ontogeny on every level of organization in an individual organism. (SeeHISTOGENESIS, , , MORPHOGENESIS, PHYLOGENY.)

REFERENCES

Shmal’gauzen, I. I. Organizm kak tseloe v individual’nom i istoricheskom razvitii. Moscow-Leningrad, 1938.
Khlopin, N. G. Obshchebiologicheskie i eksperimental’nye osnovy gistologii. Moscow, 1946.
Severtsov, A. N. Morfologicheskie zakonomemosti evoliutsii: Sobr. soch., vol. 5. Moscow-Leningrad, 1949.
Zavarzin, A. A. Izbr. trudy, vols. 1–4. Moscow-Leningrad, 1950–53.
Shmal’gauzen, I. I. “Integratsiia biologicheskikh sistem i ikh samoreguliatsiia.” Biul. Moskovskogo obshchestva ispytatelei prirody; Otdel biologicheskii, 1961, vol. 66, fasc. 2.
Shmal’gauzen, I. I. Reguliatsiia formoobrazovaniia v individual’nom razvitii. Moscow, 1964.
Amlinskii, I. E. “Nekotorye problemy stanovleniia mnogokletochnosti.” In the collection Struktura i formy materii. Moscow, 1967.
Ryzhkov, V. L. “Mesto individa sredi biologicheskikh sistem.” In the collection Razvitie kontseptsii strukturnykh urovnei v biologii. Moscow, 1972.
De Beer, G. R. Embryos and Ancestors. Oxford, 1958.
Regulation and Control in Living Systems. Edited by H. Kalmus. New York, 1967.

I. E. AMLINSKII

organism

[′ȯr·gə‚niz·əm]
(biology)
An individual constituted to carry out all life functions.
References in classic literature ?
Socialism, Communism, or whatever one chooses to call it, by converting private property into public wealth, and substituting co-operation for competition, will restore society to its proper condition of a thoroughly healthy organism, and insure the material well-being of each member of the community.
The characteristic is not wholly confined to living organisms.
Before dawn the black vapour was pouring through the streets of Richmond, and the disintegrating organism of government was, with a last expiring effort, rousing the population of London to the necessity of flight.
These virtues, so common all round him now, had been dormant in his own organism - where it might be said of them perhaps that they had slept the sleep of the just.
That hissing pant, as regular and full-volumed as the exhaust of an engine, spoke of a monstrous organism.
They followed the road with a sensation that they were soaring along in a supporting medium, possessed of original and profound thoughts, themselves and surrounding nature forming an organism of which all the parts harmoniously and joyously interpenetrated each other.
Naked and unarmed, as I was, my end would have been both speedy and horrible at the hands of these cruel creatures had I had time to put my resolve into execution, but at the moment of the shriek each member of the herd turned in the direction from which the sound seemed to come, and at the same instant every particular snake-like hair upon their heads rose stiffly perpendicular as if each had been a sentient organism looking or listening for the source or meaning of the wail.
There was just that shadowiness about them which you find in people whose lives are part of the social organism, so that they exist in it and by it only.
And experiences of the same kind are necessary for the individual to become conscious of himself; but here there is the difference that, although everyone becomes equally conscious of his body as a separate and complete organism, everyone does not become equally conscious of himself as a complete and separate personality.
Probably, because the ape's would be far simpler than those of the higher organism.
In the organism of states such men are necessary, as wolves are necessary in the organism of nature, and they always exist, always appear and hold their own, however incongruous their presence and their proximity to the head of the government may be.
This great seer did not go beyond the consideration of the tissues as ultimate facts in the living organism, marking the limit of anatomical analysis; but it was open to another mind to say, have not these structures some common basis from which they have all started, as your sarsnet, gauze, net, satin, and velvet from the raw cocoon?

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