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SPECIES

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Originally appearing in Volume V25, Page 617 of the 1911 Encyclopedia Britannica.
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SPECIES , a See also:

term, in its See also:general and once See also:familiar significance, applied indiscriminately to animate and inanimate See also:objects and to abstract conceptions or ideas, as denoting a particular phase, or sort, in which anything might appear. In See also:logic it came to be used as the See also:translation of the Gr. eZbos, and meant a number of individuals having See also:common characters See also:peculiar to them, and so forming a See also:group which with other See also:groups were included in a higher group. The application of the term was purely relative, for the higher group itself might be one of the " species, " or modes of a still higher group. In See also:medicine it was used for the constituents of a See also:prescription. In See also:algebra it denoted the characters which represented quantities in an See also:equation. See also:Early writers on natural See also:history used the term in its vague logical sense without limiting it to a See also:special See also:category in the See also:hierarchy of See also:classification. To See also:John See also:Ray, the famous See also:English naturalist, the See also:credit is generally given of first making species a definite term in See also:zoology and See also:botany, but Ray owed much of his classification to Kaspar or Gaspard See also:Bauhin (1550-1624), profressor of See also:Greek and of See also:Anatomy and Botany at See also:Basel, and much of his clear See also:definition of terms to an unpublished MS. of See also:Joachim See also:Jung of See also:Hamburg (1587-1657). See also:Sir W. T. Thisleton See also:Dyer (See also:Edinburgh See also:Review, 1902, p. 370) thinks that Ray's use of the word may be traced to the last-mentioned authors. It is clear, however, that through Ray's See also:work in the 17th See also:century the common biological application of species became fixed much in its See also:modern See also:form, as denoting a group of animals or See also:plants capable of interbreeding, and although not necessarily quite identical, with marked common characters.

Working on these lines, and attaching special importance to common descent, naturalists applied the term with more and more precision, until See also:

Linnaeus, in his Philosophia botanica, gave the See also:aphorism, " species tot aunt diversae, quot diversae format ab initio aunt creatae "—" just so many species are to be reckoned as there were forms created at the beginning. " Linnaeus' invention of See also:binomial nomenclature for designating species served systematic See also:biology admirably, but at the same See also:time, by attaching preponderating importance to a particular grade in classification, crystallized the See also:doctrine of fixity. The See also:lower grades in classification such as sub-species and varieties on the one See also:hand, and the higher grades on the other, such as genera and families, were admitted to be human conceptions imposed on the living See also:world, but species were See also:concrete, See also:objective existences to be discovered and named. G. L. L. See also:Buffon and J. P. B. See also:Lamarck practically conceded the objective existence of species in arguing that they might be modified by See also:external conditions, and G. L. See also:Cuvier proclaimed their fixity without reserve.

See also:

Charles See also:Darwin found the conception of species so definite and fixed that he See also:chose for the See also:title of his See also:great See also:book (1859) the words On the Origin of Species by Means of Natural Selection, although his exposition of See also:evolution applied equally to every grade in classification. E. B. Poulton, in an admirable discussion of contemporary views regarding species (presidential address to the Entomological Society of See also:London 1904), has shown that Darwin did not believe in the objective existence of species, not only because he was led to discard the See also:hypothesis of special creation as the explanation of the polymorphism of See also:life, but because in practice as a working systematist he could neither find for himself nor ascertain from other systematists any settled criteria by which a group of specimens could be elevated into a genus, accepted as a species; or regarded as a variety. The vast advance in knowledge of the existing forms of living things that has been acquired and recorded since 1859 has accentuated the difficulty of finding any morphological criteria for species. A few writers have insisted that they are discontinuous, and that real gaps exist between them. Equally great gaps, however, may exist between See also:males and See also:females, between See also:climatic phases or summer and See also:winter forms. The See also:attempt to find a physiological criterion has similarly failed; many forms that have been universally accepted as true species produce fertile hybrids (see See also:HYBRIDISM). In modern practice (see ZOOLOGICAL NOMENCLATURE) systematists no longer regard species as more than as an artificial See also:rank in classification, to be applied chiefly for reasons of convenience, so that the word is reverting to its older logical significance. The word " species " now signifies a grade or rank in classification assigned by systematists to an assemblage of organic forms which they See also:judge to be more closely interrelated by common descent than they are related to forms judged to be outside the species, and of which the known individuals, if they differ amongst them-selves, differ less markedly than they do from those outside the species, or, if differing markedly, are linked by intermediate forms. It is to be noted that the individuals may themselves be judged to fall into groups of See also:minor rank, known as sub-species or See also:local varieties, but such subordinate assemblages are elevated to specific rank, if they appear not to intergrade so as to form a linked species, whilst on the other hand assemblages judged to be species are merged, or degraded to sub-species, if they are found to intergrade by discoveries of linking forms. A species, in See also:short, is a subjective conception, and some writers, as for instance E.

Ray Lankester, have urged that the word is so firmly asssociated with See also:

historical implications of fixity which are now incongruous with its application, that it ought to be discarded from scientific nomenclature. In technical biology each species is designated by two words, one for the genus, printed with an initial See also:capital, and one for the particular species, printed without an initial capital in Zoology, whilst in Botany the See also:habit once common to both subjects is retained, and the specific name if derived from a proper name is printed with a capital. The two words are printed in italics, and may be followed by the name of the author who first described the species. Thus " Canis vulpes Linnaeus " is the specific designation of the common See also:fox, Canis being the generic term common to See also:dogs, wolves and so forth, and vulpes indicating the particular species, whilst the attached author's name indicates that Linnaeus first named the species in question. (P. C.

End of Article: SPECIES

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