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Export to Excel select * from OriginOfSpecies where ordinal = '40' order by subject limit 24, 4 (Page 7: Row)
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description
06 - Difficutiles in Theory 06-09 - Cases of Difficulty 40 In the foregoing cases, we see the same end gained and the same function performed, in beings not at all or only remotely allied, by organs in appearance, though not in development, closely similar.

On the other hand, it is a common rule throughout nature that the same end should be gained, even sometimes in the case of closely-related beings, by the most diversified means.

How differently constructed is the feathered wing of a bird and the membrane-covered wing of a bat; and still more so the four wings of a butterfly, the two wings of a fly, and the two wings with the elytra of a beetle.
bird
bird

bat
bat

butterfly
butterfly

fly
fly

beetle
beetle

elytra
elytra


Bivalve shells are made to open and shut, but on what a number of patterns is the hinge constructed,- from the long row of neatly interlocking teeth in a Nucula to the simple ligament of a Mussel!
Sea Shell
Sea Shell

nucula
nucula

mussel
mussel


Seeds are disseminated by their minuteness,- by their capsule being converted into a light balloon-like envelope,- by being embedded in pulp or flesh, formed of the most diverse parts, and rendered nutritious, as well as conspicuously coloured, so as to attract and be devoured by birds,- by having hooks and grapnels of many kinds and serrated arms, so as to adhere to the fur of quadrupeds,- and by being furnished with wings and plumes, as different in shape as they are elegant in structure, so as to be wafted by every breeze.
Flying Seeds
Flying Seeds


I will give one other instance; for this subject of the same end being gained by the most diversified means well deserves attention.

Some authors maintain that organic beings have been formed in many ways for the sake of mere variety, almost like toys in a shop, but such a view of nature is incredible.

With plants having separated sexes, and with those in which, though hermaphrodites, the pollen does not spontaneously fall on the stigma, some aid is necessary for their fertilisation.

With several kinds this is effected by the pollen-grains, which are light and incoherent, being blown by the wind through mere chance on to the stigma; and this is the simplest plan which can well be conceived.
pollen
pollen


An almost equally simple, though very different, plan occurs in many plants in which a symmetrical flower secretes a few drops of nectar, and is consequently visited by insects; and these carry the pollen from the anthers to the stigma.
anther
anther
06 - Difficutiles in Theory 06-04 - Transitions in Habits of Life 40 Now look at the Galeopithecus or so-called flying lemur, which formerly was ranked amongst bats, but is now believed to belong to the Insectivora.
lemur
lemur

Flying Lemur
Flying Lemur


An extremely wide flank membrane stretches from the corners of the jaw to the tail, and includes the limbs with the elongated fingers. This flank-membrane is furnished with an extensor muscle.

Although no graduated links of structure, fitted for gliding through the air, now connect the Galeopithecus with the other Insectivora, yet there is no difficulty in supposing that such links formerly existed, and that each was developed in the same manner as with the less perfectly gliding squirrels; each grade of structure having been useful to its possessor.

Nor can I see any insuperable difficulty in further believing that the membrane connected fingers and fore-arm of the Galeopithecus might have been greatly lengthened by natural selection; and this, as far as the organs of flight are concerned, would have converted the animal into a bat.
bat
bat


In certain bats in which the wing-membrane extends from the top of the shoulder to the tail and includes the hind-legs, we perhaps see traces of an apparatus originally fitted for gliding through the air rather than for flight.
06 - Difficutiles in Theory 06-08 - Means of Transition 40 According to this view it may be inferred that all vertebrate animals with true lungs are descended by ordinary generation from an ancient and unknown prototype, which was furnished with a floating apparatus or swimbladder.

We can thus, as I infer from Owen's interesting description of these parts, understand the strange fact that every particle of food and drink & which we swallow has to pass over the orifice of the trachea, with some risk of falling into the lungs, notwithstanding the beautiful contrivance by which the glottis is closed. In the higher Vertebrate the branchiae have wholly disappeared- but in the embryo the slits on the sides of the neck and the loop-like course of the arteries still mark their former position.

But it is conceivable that the now utterly lost branchiae might have been gradually worked in by natural selection for some distinct purpose: for instance, Landois has shown that the wings of insects are developed from the tracheae; it is therefore highly probable that in this great class organs which once served for respiration have been actually converted into organs for flight.
gills
gills

Swim Bladder
Swim Bladder

lungs
lungs

wings
wings
06 - Difficutiles in Theory 06-11 - Organs of Small Importance 40 In the second place, we may easily err in attributing importance to characters, and in believing that they have been developed through natural selection.

We must by no means overlook the effects of the definite action of changed conditions of life,- of so-called spontaneous variations, which seem to depend in a quite subordinate degree on the nature of the conditions,- of the tendency to reversion to long-lost characters,- of the complex laws of growth, such as of correlation, compensation, of the pressure of one part on another, &c.,- and finally of sexual selection, by which characters of use to one sex are often gained and then transmitted more or less perfectly to the other sex, though of no use to this sex.

But structures thus indirectly gained, although at first of no advantage to a species, may subsequently have been taken advantage of by its modified descendants, under new conditions of life and newly acquired habits.