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  Morphology (Greek, ‘study of forms’), in the life sciences, is the study of organic form and of similarity in form between different organisms. It was founded in the early 17th century by Johann von Goethe, though previous thinkers such as Aristotle and Pierre Belon, in the 16th century, had compared the shapes of animals and noted similarities in structure. Goethe suggested that all plant parts were derived from a primordial plant organ, which was a leaf. Étienne Geoffroy, St., Hilaire (1772 - 1844) proposed a similar idea in zoology: that all animals, including man, are constructed according to the same basic ground plan.

In the 19th century, Karl von Baer proposed that all animals came from a common ‘germ’—for example, a chick embryo begins its development with a morphology which is common to any animal embryo, and becomes a general vertebrate and then a specialized (bird) vertebrate before finally differentiating into the chicken morphology. This led to the idea of the archetype, defined by , Richard Owen (1804 - 1894) as a hypothetical form with the potential to develop into any of the species in a group. Owen and others applied their ideas of morphology to existing knowledge of anatomy, at that time one of the best-studied areas of biology. , Georges Cuvier (1769 - 1832) divided the animal kingdom into four physiological groups, which he called vertebrates, articulates, molluscs and radiates, but only on the basis of functional similarity. In common with the prevailing opinion in the early 19th century, Cuvier would not admit that species which were similar in morphology were of the same type. In 1830, Cuvier and Geoffroy argued their positions before the Paris Academy of Sciences and, though Cuvier was the victor and Geoffroy\'s ideas of a single, primordial animal were rejected, the unity of type approach endured. Owen used his ideas of archetype to explain the fossil record which showed ancient, simple, general species and more modern complex, specialized species.

The development of morphology set the scene for Darwin, who proposed evolution as a mechanism to explain the observed unity of type, in which the archetype was a real, extinct species, the common ancestor of a group. Modern morphology has shifted its emphasis to attempts to relate structure and shape to function.

Morphology, of a different kind, is an important theory in linguistics. Each segment of meaning in a word constitutes a separate morpheme, so in the word ‘untrue’ we can isolate two morphemes: negation (denoted by un-) and true. The fundamental concern of morphology, therefore, is the internal structure of words. Some morphemes can take more than one form, as demonstrated by the morpheme for the simple past tense. In ‘walked’, the past tense morpheme (spelt ed) is pronounced t; in ‘smiled’ it is pronounced as d; whereas in ‘shouted’ it appears as id. In effect, a single unit of meaning is expressible in a variety of ways, which leads to the conclusion that the morpheme is an abstract category which finds physical realization in the form of morphs. It follows then that t, d, id are all allomorphs (associated morphs) of the morpheme for simple past tense. The abstract nature of morphemes is further demonstrated by the refusal of certain words to be neatly segmented into a sequence of distinct parts. Thus ‘women’ is composed of the separate morphemes woman and plural, which seem to have blended imperceptibly. The synthesis of morphemes in this way is accounted for by so-called morphological processes, whereby separate elements combine to produce a unified word form.

A useful distinction in morphological theory is drawn between free morphs and bound morphs. Free morphs, like ‘prawn’ and ‘alabaster’, can exist independently, whereas bound morphs, like ‘-ed’ and ‘-ing’, cannot stand alone and only find legitimate expression as part of a word (for example, ‘talked’, ‘talking’). Morphs can also be distinguished according to whether they are fundamentally lexical or grammatical in nature. Lexical morphs, such as ‘non-’, ‘conform’ and ‘-ist’, can be used to build up new word forms (for example, ‘nonconformist’), whereas grammatical morphs, like the third person singular marker ‘-s’, only express meaning within a grammatical construction (for example, ‘walks’).

Categories such as tense, number and gender are often expressed as inflections on word stems and serve to highlight the fuzzy boundary between morphology and syntax, since they often affect not only the words they appear in, but the position of the surrounding words also. Inflectional processes of this kind can be distinguished from derivational processes, in which new words are created, by adding affixes to a stem. For example, we can add the suffix ‘-able’ to ‘describe’ to give ‘describable’, which can then be prefixed with ‘in-’, to produce ‘indescribable’. One problem in morphology is to explain the constraints on derivational processes which block, for instance, forms like ‘indescribe’. A further problem is to describe how derivational processes influence word class membership (noun, verb, adjective and so on). Thus, the derivation of ‘denial’ from ‘deny’ is class-changing, since it transforms a verb into a noun, whereas a class-maintaining process leaves word-class membership unaffected, as in the derivation of ‘dislike’ from ‘like’ (both verbs). An alternative method of creating new words, known as compounding, involves the conjunction of morphemes which can otherwise occur independently. Examples include compounds—such as ‘blackboard’, ‘bedroom’ and ‘gearbox’—which have meanings independent of their constituent parts, and which function as single word units. As a result, the individual components are no longer available for inflectional processes, which explains the impossibility of forms like ‘gearsbox’. MS RB

See also analogy; Darwinism; embryology; homology; palaeontology.Further reading L. Bauer, English Word-Formation; , P.H. Matthews, Morphology.



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