Word Finder - metamorphosis

definition

A transformation, such as one performed by magic.

definition

A noticeable change in character, appearance, function or condition.

definition

A change in the form and often habits of an animal after the embryonic stage during normal development. (e.g. the transformation of a caterpillar into a butterfly or a tadpole into a frog.)

definition

A change in the structure of a specific body tissue. Usually degenerative.

In some cases (many species of Ascaris) the metamorphosis is reduced to a simple process of growth.

The weight of Malpighi's observations therefore fell into the scale of that doctrine which Harvey terms metamorphosis, in contradistinction to epigenesis.

He thus views the consecration of the elements as akin to other consecrations; and, like priestly ordination, as involving " a metamorphosis for the better," a phrase which later on became classical.

A dragonfly goes through a metamorphosis period just like a butterfly.

Much consideration has been given to the nature of metamorphosis in insects, to its value to the creatures and to the mode of its origin.

Miller discovered that they undergo a metamorphosis, and that the minute worm-like lamperns previously known under the name of Ammocoetes, and abundant in the sand and mud of many streams, were nothing but the undeveloped young of the river-lampreys and small lamperns.

A common result of metamorphosis is that the larva and imago differ markedly in their habitat and mode of feeding.

The differences in appearance between the caterpillar and the butterfly, striking as they are to the eye, do not sufficiently represent the phenomena of metamorphosis to the intelligence.

These Polystomum deposit their eggs in the branchial chamber and die at the metamorphosis of their host.

The fascinating difficulties presented to the student by the metamorphosis of the Hexapoda are to some extent explained, as he ponders over the evolution of the class.

In the Metanemertini, as far as they have been investigated, a direct development without metamorphosis has been observed.

The ciliated larva escapes from the egg into the water and enters an intermediate host (leech, mollusc, arthropod, batrachian or fish) where it undergoes a metamorphosis into a second stage in which most of the adult organs are present.

This migration is usually accompanied by a more or less complete metamorphosis.

As regards their life history, all Hymenoptera undergo a " complete " metamorphosis.

Fleas are oviparous, and undergo a very complete metamorphosis.

A natural system must take into account the nature of the larva and of the metamorphosis in conjunction with the general characters of the imago.

Metamorphosis Design offers a similarly impressive collection of the popular CSS designed templates.

Those who were unwilling to accept evolution, without better grounds than such as are offered by Lamarck, and who therefore preferred to suspend their judgment on the question, found in the principle of selective breeding, pursued in all its applications with marvellous knowledge and skill by Darwin, a valid explanation of the occurrence of varieties and races; and they saw clearly that, if the explanation would apply to species, it would not only solve the problem of their evolution, but that it would account for the facts of teleology, as well as for those of morphology; and for the persistence of some forms of life unchanged through long epochs of time, while others undergo comparatively rapid metamorphosis.

Owing to more or less herbivorous habits, the intestine is exceedingly elongate and much convoluted, being several times larger and of a greater calibre than after the metamorphosis.

The word metamorphosis cannot, in fact, be used any longer in its original sense, for the change which it implied does not normally occur in ontogeny, and in phylogeny the idea is more accurately expressed by the term differentiation.

As regards growth after hatching, all beetles undergo a "complete" metamorphosis, the wing-rudiments developing beneath the cuticle throughout the larval stages, and a resting pupal stage intervening between the last larval instal1 and the imago.

Metamorphosis in Diptera is complete; the larvae are utterly different from the perfect insects in appearance, and, although varying greatly in outward form, are usually footless grubs; those of the Muscidae are generally known as maggots.

In such cases the development of wings and the attainment of the adult form depend upon a more or less profound transformation or metamorphosis.

The new instar - or temporary form - is often very different from the old one, and this is the essential fact of metamorphosis.

The unlikeness of the young insect to its parent is one of the factors that necessitates metamorphosis.

At its first metamorphosis it produces a caterpillar, then a bombylius and lastly a chrysalis - all these changes taking place within six months.

The first soma is supposed to have been stolen from its guardian demon by an eagle, this soma-bringing eagle of Indra being comparable with the nectar-bringing eagle of Zeus, and with the eagle which, as a metamorphosis of Odin, carried off the mead.

Although several species belonging to the second class occasionally enter the bodies of water snails and other animals before reaching their definitive host, they undergo no alteration of form in this intermediate host; the case is different, however, in Filaria medinensis and other forms, in which a free larval is followed by a parasitic existence in two distinct hosts, all the changes being accompanied by a metamorphosis.

The process of destruction of the larval tissues was first studied in the forms where metamorphosis is greatest and most abrupt, viz.

Insect metamorphosis may be briefly described as phenomena of development characterized by abrupt changes of appearance and of structure, occurring during the period subsequent to embryonic development and antecedent to the reproductive state.

Amongst insects with imperfect metamorphosis the nearest approximations to the true pupa of the Holometabola are to be found in the subimago a From Chittenden, Bull.

This is a most remarkable case, but unfortunately very little information exists as to the details of metamorphosis in this group.

The post-embryonic growth of Hexapods with or without metamorphosis is accompanied in most cases by the acquisition of wings.

In connexion with the question whether metamorphosis has been gradually acquired, we have to consider two aspects, viz.

None of the groups of existing Endopterygota have been traced with certainty farther back than the Mesozoic epoch, and all the numerous Palaeozoic insect-fossils seem to belong to forms that possessed only imperfect metamorphosis.

It is now, in fact, generally admitted that metamorphosis has been acquired comparatively recently, and Scudder in his review of the earliest fossil insects states that " their metamorphoses were simple and incomplete, the young leaving the egg with the form of the parent, but without wings, the assumption of which required no quiescent stage before maturity."

The eruciform larva of the Orthorrhapha leads on to the headless vermiform maggot of the Cyclorrhapha, and in the latter sub-order we find metamorphosis carried to its extreme point, the muscid flies being the most highly specialized of all the Hexapoda as regards structure, while their maggots are the most degraded of all insect larvae.

The Siphonaptera appear by the form of the larva and the nature of the metamorphosis to be akin to the Orthorrhapha - in which division they have indeed been included by many students.

Meanwhile the English naturalist, John Ray, was studying the classification of animals; he published, in 1705, his Methodus insectorum, in which the nature of the metamorphosis received due weight.

Both Hetero- and Metane- mertini have been more exhaustively studied than the other two groups, the first, as was noticed above, being characterized by peculiar larval forms, the second developing without metamorphosis.

Two pairs of invaginations of B the skin, which originally are called the prostomial and metastomial disks, grow round the intestine, finally fuse together, and form the skin and mus- cular body-wall of the future Nemertine, which afterwards becomes ciliated, frees itself from the pilidium investment and develops into the adult worm without further metamorphosis.

It appears.probable that this is only a further simplification of the more complicated metamorphosis described above.

During this period he published his poetical satire called Metamorphosis (1726), his Epistolae ad virum perillustrem (1727), his Description of Denmark and Norway (1729), History of Denmark, Universal Church History, Biographies of Famous Men, Moral Reflections, Description of Bergen (1737), A History of the Jews, and other learned and laborious compilations.

Both agree in having nothing that can be termed a metamorphosis; they are active from the time of their exit from the egg to their death, gradually increasing in size, and undergoing several moults or changes of skin.

In the former position the suckers are developed and growth proceeds for 8 to Io weeks until the metamorphosis of its host.

His cult survived the metamorphosis of the ancient Vedic nature-worship into modern Hinduism, and there still are in India fire-priests (agnihotri) whose duty is to superintend his worship. The sacred fire-drill for procuring the temple-fire by friction - symbolic of Agni's daily miraculous birth - is still used.

The order of the Hemiptera affords, ` therefore, some interesting transition stages towards the complete metamorphosis of the higher insects.

Localities at such altitudes not being, as a rule, suitable for larval life in the water, the young are retained in the uterus, until the completion of the metamorphosis.

In the latter respect, and in the fact that they frequently develop by a metamorphosis, they approach the Mollusca, but they differ from that group notably in the occurrence of metameric segmentation affecting many of the systems of organs.

He has observed that in young specimens of Siren lacertina (the larva is still unknown) the gills are rudimentary and functionless, and that it is only in large adult specimens that they are fully developed in structure and function; he therefore concludes that the sirens are the descendants of a terrestrial type of batrachians, which passed through a metamorphosis like the other members of their class, but that more recently they have adopted a permanently aquatic life, and have resumed their branchiae by reversion.