Higher development and progressive tendencies invariably tend shorten and condense the early stages growth. Hence the value such cases as those the frogs and their neighbours, which, through mode life, habits, and other and unknown conditions, have retained much their original way life, and have revealed through a literal byeway development, the original and primitive phases that all other animal forms.
The conditions which favour or retard such developments are often obscure, or very frequently unknown.
The presence water or its absence, for instance, would favour or retard the continuance the metamorphosis in the frog class.
We must also bear in mind that geological changes, the rising and sinking land and the like, the conversion swamps and morasses into dry land and similar physical changes, are powerful factors in producing modifications habit, and, through change habit, effecting variations in structure and form. It possible prove the existence and operation such changes from many points view. Both from the zoological or biological side, and from that geology itself, the importance such alterations the earth's surface can proved. This aspect the subject may find appropriate illustration in papers devoted the facts geographical distribution and their explanation, whilst may not neglect observe the strictly utilitarian points involved in such abbreviated life-histories as those have been discussing. It has been noted that as ascend in the scale animal and plant life, development becomes more and more condensed and abbreviated.
On posteriori grounds might argue that, from the fact such condensation accompanying higher life and progressive development, some obvious advantage in the struggle for existence was thereby gained. The nature such advantage not difficult discover.
The more prolonged and exposed larval or early existence the more likely are the young forms succumb from loss food, change surroundings, or from the attack enemies and numerous other conditions.
On the contrary, with an abbreviated infancy, the animal obtains a distinct coign vantage.
There less risk early death, and a greater prospect an earlier and stronger maturity. Thus the selected races are those which possess the shorter and more condensed life history, and these races, therefore, come the front in the universal struggle for existence which besets and surrounds the living hosts to-day as yore.
As John Lubbock remarks, when speaking the shortening the insect's life history The compression and even disappearance those embryonal stages which are no longer adapted the mode life which not benefit the animal a phenomenon not without a parallel in other parts the animal or even the vegetable kingdom.
Just as in language college essay help long island long compound words have a tendency concision, buy academic papers and single letters sometimes linger indicating the history a have ceased influence the sound in embryology useless stages, interesdng thesis proposal writing as illustrations past history, but without direct advantage under present conditions, are rapidly passed through, and even as would appear, in some cases altogether omitted. its peculiar development, writing assignment help as from its Ambly stoma. Such a change was almost equivalent that whereby order custom essays a frog could metamorphosed into a toad, and hence excited no small surprise in the zoological world. By careful experimentation a lady naturalist, Fraulein von Chauvin, showed that gradually inuring the axolotl first a life amongst damp moss, and then an existence entirely removed from the water, could made assume the amblystoma-form, with its black skin and thesis formatting buying papers online college yellow spots. Such a case illustrates powerfully help write essay the efifects a change surroundings in homework help essay writing metamorphosing a species. A succession dry seasons, operating in the past, has most likely been the active origin the amblystoma race from the axolotl stock. Presumably the axolotl, as the gill-bearing form, the primitive stock the amblystomas being a derived race, but nevertheless representing a true species which the axolotl, conversely, may termed the larval form. To this relationship, however, reference will subsequently made. help with developing a thesis statement The shrivelling the gills in this case, noteworthy, was clearly due a mechanical cause, that dryness surroundings.
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