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OriginOfSpecies - 475 Rows
Column Type #Values Column Stats
id int(11) 475 Column Stats
subject varchar(80) 14 Column Stats
title varchar(250) 139 Column Stats
ordinal int(11) 30 Column Stats
description text 474 Column Stats

475 rows, page 55 of 119 (4/p)
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Export to Excel select * from OriginOfSpecies order by description desc limit 216, 4 (Page 55: Row)
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title
ordinal
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01 - Variations Under Domestication 01-08 - Breeds of the Domestic Pigeons, their Differences and Origin 60 Lastly, the hybrids or mongrels from between all the breeds of the pigeon are perfectly fertile, as I can state from my own observations, purposely made, on the most distinct breeds.

Now, hardly any cases have been ascertained with certainty of hybrids from two quite distinct species of animals being perfectly fertile.

Some authors believe that long-continued domestication eliminates this strong tendency to sterility in species.

From the history of the dog, and of some other domestic animals, this conclusion is probably quite correct, if applied to species closely related to each other.

But to extend it so far as to suppose that species, aboriginally as distinct as carriers, tumblers, pouters, and fantails now are, should yield offspring perfectly fertile inter se, would be rash in the extreme.

Rock Pigeon
Rock Pigeon

Dog
Dog
06 - Difficutiles in Theory 06-03 - Absence or Rarity of Transitional Varieties 100 Lastly, looking not to any one time, but to all time, if my theory be true, numberless intermediate varieties, linking closely together all the species of the same group, must assuredly have existed; but the very process of natural selection constantly tends, as has been so often remarked, to exterminate the parent-forms and the intermediate links.

Consequently evidence of their former existence could be found only amongst fossil remains, which are preserved, as we shall attempt to show in a future chapter, in an extremely imperfect and intermittent record.
04 - Natural Selection 04-09 - Circumstances favourable for the production of new forms through Natural Selection 70 Lapse of time is only so far important, and its importance in this respect is great, that it gives a better chance of beneficial variations arising and of their being selected, accumulated, and fixed. It likewise tends to increase the direct action of the physical conditions of life, in relation to the constitution of each organism.

If we turn to nature to test the truth of these remarks, and look at any small isolated area, such as an oceanic island, although the number of species inhabiting it is small, as we shall see in our chapter on Geographical Distribution; yet of these species a very large proportion are endemic,- that is, have been produced there and nowhere else in the world. Hence an oceanic island at first sight seems to have been highly favourable for the production of new species.

island
island

Galapagos Islands
Galapagos Islands

Galapagos Tortoise
Galapagos Tortoise
05 - Laws of Variation 05-02 - Use and Disuse of Parts, combined with Natural Selection, Organs of Flight and Vision 20 Kirby has remarked (and I have observed the same fact) that the anterior tarsi, or feet, of many male dung-feeding beetles are often broken off; he examined seventeen specimens in his own collection, and not one had even a relic left.

beetle
beetle


In the Onites apelles, [?], the tarsi are so habitually lost, that the insect has been described as not having them.
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In some other genera they are present, but in a rudimentary condition.

In the Ateuchus, or sacred beetle of the Egyptians, they are totally deficient.

ateuchus
ateuchus


The evidence that accidental mutilations can be inherited is at present not decisive; but the remarkable cases observed by Brown-Sequard in guinea-pigs, of the inherited effects of operations, should make us cautious in denying this tendency.

Guinea
Guinea

Guinea Pig
Guinea Pig


Hence it will perhaps be safest to look at the entire absence of the anterior tarsi in Ateuchus, and their rudimentary condition in some other genera, not as cases of inherited mutilations, but as due to the effects of long-continued disuse; for as many dung-feeding beetles are generally found with their tarsi lost, this must happen early in life; therefore the tarsi cannot be of much importance or be much used by these insects.

ateuchus
ateuchus