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Export to Excel select * from OriginOfSpecies where subject = '04 - Natural Selection' order by description limit 20, 4 (Page 6: Row)
subject
title
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description Desending Order (top row is first)
04 - Natural Selection 04-12 - On the Degree to which Organisation tends to advance 30 But we shall see how obscure this subject is if we look, for instance, to fishes, amongst which some naturalists rank those as highest which, like the sharks, approach nearest to amphibians; whilst other naturalists rank the common bony or teleostean fishes as the highest, inasmuch as they are most strictly fish-like and differ most from the other vertebrate classes.

shark
shark


We see still more plainly the obscurity of the subject by turning to plants, amongst which the standard of intellect is of course quite excluded; and here some botanists rank those plants as highest which have every organ, as sepals, petals, stamens, and pistils, fully developed in each flower; whereas other botanists, probably with more truth, look at the plants which have their several organs much modified and reduced in number as the highest.
04 - Natural Selection 04-09 - Circumstances favourable for the production of new forms through Natural Selection 30 But we shall see in the sixth chapter that intermediate varieties, inhabiting intermediate districts, will in the long run generally be supplanted by one of the adjoining varieties.

Intercrossing will chiefly affect those animals which unite for each birth and wander much, and which do not breed at a very quick rate.

Hence with animals of this nature, for instance, birds, varieties will generally be confined to separated countries; and this I find to be the case.

With hermaphrodite organisms which cross only ccasionally, and likewise with animals which unite for each birth, but which wander little and can increase at a rapid rate, a new
and improved variety might be quickly formed on any one spot, and might there maintain itself in a body and afterwards spread, so that the individuals of the new variety would chiefly cross together.

On this principle, nurserymen always prefer saving seed from a large body of plants, as the chance of intercrossing is thus lessened.

snail
snail
04 - Natural Selection 04-11 - Divergence of Character 70 By considering the nature of the plants or animals which have in any country struggled successfully with the indigenes and have there become naturalised, we may gain some crude idea in what manner some of the natives would have to be modified, in order to gain an advantage over their compatriots; and we may at least infer that diversification of structure, amounting to new generic differences, would be profitable to them.
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