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Export to Excel select * from OriginOfSpecies where title = '06-06 - Species with Habits Widely Diffferent from those of their Allies' order by subject, title, ordinal ( Row)
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06 - Difficutiles in Theory 06-06 - Species with Habits Widely Diffferent from those of their Allies 10 Petrels are the most aerial and oceanic of birds, but in the quiet sounds of Tierra del Fuego, the Puffinuria berardi, in its general habits, in its astonishing power of diving, in its manner of swimming and of flying when made to take flight, would be mistaken by any one for an auk or a grebe; nevertheless it is essentially a petrel, but with many parts of its organisation profoundly modified in relation to its new habits of life; whereas the woodpecker of La Plata has had its structure only slightly modified.

In the case of the waterouzel, the acutest observer by examining its dead body would never have suspected its subaquatic habits; yet this bird, which is allied to the thrush family, subsists by diving- using its wings under water, and grasping stones with its feet.
petrel
petrel

Tierra del Fuego
Tierra del Fuego

auk
auk


All the members of the great order of hymenopterous insects are terrestrial excepting the genus Proctotrupes, which Sir John Lubbock has discovered to be aquatic in its habits; it often enters the water and dives about by the use not of its legs but of its wings, and remains as long as four hours beneath the surface; yet it exhibits no modification in structure in accordance with its abnormal habits.
06 - Difficutiles in Theory 06-06 - Species with Habits Widely Diffferent from those of their Allies 20 He who believes that each being has been created as we now see it, must occasionally have felt surprise when he has met with an animal having habits and structure not in agreement.

What can be plainer than that the webbed feet of ducks and geese are formed for swimming?

duck
duck

goose
goose


Yet there are upland geese with webbed feet which rarely go near the water; and no one except Audubon has seen the frigate-bird, which has all its four toes webbed, alight on the surface of the ocean.

Frigate Bird
Frigate Bird


On the other hand, grebes and coots are eminently aquatic, although their toes are only bordered by membrane.

grebe
grebe

coot
coot


What seems plainer than that the long toes, not furnished with membrane, of the Grallatores are formed for walking over swamps and floating plants?- the water-hen and landrail are members of this order, yet the first is nearly as aquatic as the coot, and the second nearly as terrestrial as the quail or partridge.
waterhen
waterhen

landrail
landrail


In such cases, and many others could be given, habits have changed without a corresponding change of structure.

The webbed feet of the upland goose may be said to have become almost rudimentary in function, though not in
structure.

In the frigate-bird, the deeply scooped membrane between the toes shows that structure has begun to change.
06 - Difficutiles in Theory 06-06 - Species with Habits Widely Diffferent from those of their Allies 30 He who believes in separate and innumerable acts of creation may say, that in these cases it has pleased the Creator to cause a being of one type to take the place of one belonging to another type; but this seems to me only re-stating the fact in dignified language.
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He who believes in the struggle for existence and in the principle of natural selection, will acknowledge that every organic being is constantly endeavouring to increase in numbers; and that if any one being varies ever so little, either in habits or structure, and thus gains an advantage over some other inhabitant of the same country, it will seize on the place of that inhabitant, however different that may be from its own place.

Hence it will cause him no surprise that there should be geese and frigatebirds with webbed feet, living on the dry land and rarely alighting on the water; that there should be long-toed corncrakes, living in meadows instead of in swamps; that there should be woodpeckers where hardly a tree grows; that there should be diving thrushes and diving Hymenoptera, and petrels with the habits of auks.
goose
goose

Frigate Bird
Frigate Bird

corncrake
corncrake

woodpecker
woodpecker

thrush
thrush

hymenoptera
hymenoptera

petrel
petrel

auk
auk