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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 84 of 119 (4/p)
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Export to Excel select * from OriginOfSpecies order by ordinal limit 332, 4 (Page 84: Row)
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04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 50 Whether organisation on the whole has actually advanced from the remotest geological periods to the present day will be more conveniently discussed in our chapter on Geological Succession.

But it may be objected that if all organic beings thus tend to rise in the scale, how is it that throughout the world a multitude of the lowest forms still exist; and how is it that in each great class some forms are far more highly developed than others?

Why have not the more highly developed forms everywhere supplanted and exterminated the lower?

Lamarck, who believed in an innate and inevitable tendency towards perfection in all organic beings, seems to have felt this difficulty so strongly, that he was led to suppose that new and simple forms are continually being produced by spontaneous generation.
05 - Laws of Variation 05-12 - Reversion to Long Lost Characters 50 With respect to the horse, I have collected cases in England of the spinal stripe in horses of the most distinct breeds, and of all colours: transverse bars on the legs are not rare in duns, mouse-duns, and in one instance in a chestnut a faint shoulder-stripe may sometimes be seen in duns, and I have seen a trace in a bay horse.

horse
horse

England
England


My son made a careful examination and sketch for me of a dun Belgian cart-horse with a double stripe on each shoulder and with leg-stripes; I have myself seen a dun Devonshire pony, and a small dun Welsh pony has been carefully described to me, both with three parallel stripes on each shoulder.

Belgian Cart Horse
Belgian Cart Horse

Welsh Pony
Welsh Pony
04 - Natural Selection 04-13 - Convergence of Character 50 Consequently there seems at first sight no limit to the amount of profitable diversification of structure, and therefore no limit to the number of species which might be produced.

We do not know that even the most prolific area is fully stocked with specific forms: at the Cape of Good Hope and in Australia, which support such an astonishing number of species, many European plants have become naturalised.

Cape of Good Hope
Cape of Good Hope

Australia
Australia

europe
europe


But geology shows us, that from an early part of the tertiary period the number of species of shells, and that from the middle part of this same period the number of mammals, has not greatly or at all increased.

Sea Shell
Sea Shell
05 - Laws of Variation 05-02 - Use and Disuse of Parts, combined with Natural Selection, Organs of Flight and Vision 50 The eyes of moles and of some burrowing rodents are rudimentary in size, and in some cases are quite covered by skin and fur.

mole
mole


This state of the eyes is probably due to gradual reduction from disuse, but aided perhaps by natural selection.

In South America, a burrowing rodent, the tucotuco, or Ctenomys, is even more subterranean in its habits than the mole; and I was assured by a Spaniard, who had often caught them, that they were frequently blind.
tucotuco
tucotuco

South America
South America


One which I kept alive was certainly in this condition, the cause, as appeared on dissection, having been inflammation of the nictitating membrane.

As frequent inflammation of the eyes must be injurious to any animal, and as eyes are certainly not necessary to animals having subterranean habits, a reduction in their size, with the adhesion of the eyelids and growth of fur over them, might in such case be an advantage; and if so, natural selection would aid the effects of disuse.