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Export to Excel select * from OriginOfSpecies where ordinal = '10' order by description limit 12, 4 (Page 4: Row)
subject
title
ordinal
description Desending Order (top row is first)
06 - Difficutiles in Theory 06-02 - Transitions 10 As natural selection acts solely by the preservation of profitable modifications, each new form will tend in a fully-stocked country to take the place of, and finally to exterminate, its own less improved parent-form and other less favoured forms with which it comes into competition.
03 - Struggle for Existence 03-10 - Struggle for Life most severe between Individuals and Varieties of the same Species 10 As the species of the same genus usually have, though by no means invariably, much similarity in habits and constitution, and always in structure, the struggle will generally be more severe between them, if they come into competition with each other, than between the species of distinct genera.

We see this in the recent extension over parts of the United States of one species of swallow having caused the decrease of another species.

United States
United States

swallow
swallow


The recent increase of the missel-thrush in parts of Scotland has caused the decrease of the song-thrush.

Scotland
Scotland

Missel Thrush
Missel Thrush

Song Thrush
Song Thrush
14 - Recapitulation and Conclusion 14-01 - Recapitulation of the difficulties on the theory of Natural Selection 10 As this whole volume is one long argument, it may be convenient to the reader to have the leading facts and inferences briefly recapitulated.

That many and grave objections may be advanced against the theory of descent with modification through natural selection, I do not deny.

I have endeavoured to give to them their full force.

Nothing at first can appear more difficult to believe than that the more complex organs and instincts should have been perfected not by means superior to, though analogous with, human reason, but by the accumulation of innumerable slight variations, each good for the individual possessor.

Nevertheless, this difficulty, though appearing to our imagination insuperably great, cannot be considered real if we admit the following propositions, namely, -- that gradations in the perfection of any organ or instinct, which we may consider, either do now exist or could have existed, each good of its kind, -- that all organs and instincts are, in ever so slight a degree, variable, -- and, lastly, that there is a struggle for existence leading to the preservation of each profitable deviation of structure or instinct.

The truth of these propositions cannot, I think, be disputed.
04 - Natural Selection 04-04 - Its Power at All Ages and on Both Sexes 10 As we see that those variations which, under domestication, appear at any particular period of life, tend to reappear in the offspring at the same period;- for instance, in the shape, size, and flavour of the seeds of the many varieties of our culinary and agricultural plants; in the caterpillar and cocoon stages of the varieties of the silk-worm; in the eggs of poultry, and in the colour of the down of their chickens; in the horns of our sheep and cattle when nearly adult;- so in a state of nature natural selection will be enabled to act on and modify organic beings at any age, by the accumulation of variations profitable at that age, and by their inheritance at a corresponding age.
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silkworm
silkworm

egg
egg

poultry
poultry

chicken
chicken

sheep
sheep

cattle
cattle


If it profit a plant to have its seeds more and more widely disseminated by the wind, I can see no greater difficulty in this being effected through natural selection, than in the cotton-planter increasing and improving by selection the down in the pods on his cotton-trees.

cotton
cotton


Natural selection may modify and adapt the larva of an insect to a score of contingencies, wholly different from those which concern the mature insect; and these modifications may affect, through correlation, the structure of the adult.

larva
larva

insect
insect


So, conversely, modifications in the adult may affect the structure of the larva; but in all cases natural selection will ensure that they shall not be injurious: for if they were so, the species would become extinct.