On the Origin of Species

by

Charles Darwin

 

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'But with regard to the material world, we can at least go so far as this--

we can perceive that events are brought about not by insulated

interpositions of Divine power, exerted in each particular case, but by the

establishment of general laws.'

 

W. Whewell: Bridgewater Treatise.

 

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'To conclude, therefore, let no man out of a weak conceit of sobriety, or

an ill-applied moderation, think or maintain, that a man can search too far

or be too well studied in the book of God's word, or in the book of God's

works; divinity or philosophy; but rather let men endeavour an endless

progress or proficience in both.'

 

Bacon: Advancement of Learning.

 

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Down, Bromley, Kent,

October 1st, 1859.

 

 

 

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On the Origin of Species by Means of Natural Selection,

or the

Preservation of Favoured Races in the Struggle for Life.

By Charles Darwin

 

 

Contents

 

Intro - I - II - III - IV - V - VI - VII - VIII - IX - X - XI - XII - XIII - XIV

 

Introduction

 

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Chapter I

Variation under Domestication

Causes of Variability -- Effects of Habit -- Correlation of Growth --

Inheritance -- Character of Domestic Varieties -- Difficulty of

distinguishing between Varieties and Species -- Origin of Domestic

Varieties from one or more Species -- Domestic Pigeons, their Differences

and Origin -- Principle of Selection anciently followed, its Effects --

Methodical and Unconscious Selection -- Unknown Origin of our Domestic

Productions -- Circumstances favourable to Man's power of Selection.

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Chapter II

Variation under Nature

Variability -- Individual Differences -- Doubtful species -- Wide ranging,

much diffused, and common species vary most -- Species of the larger genera

in any country vary more than the species of the smaller genera -- Many of

the species of the larger genera resemble varieties in being very closely,

but unequally, related to each other, and in having restricted ranges.

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Chapter III

Struggle for Existence

Bears on natural selection -- The term used in a wide sense -- Geometrical

powers of increase -- Rapid increase of naturalised animals and plants --

Nature of the checks to increase -- Competition universal -- Effects of

climate -- Protection from the number of individuals -- Complex relations

of all animals and plants throughout nature -- Struggle for life most

severe between individuals and varieties of the same species; often severe

between species of the same genus -- The relation of organism to organism

the most important of all relations.

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Chapter IV

Natural Selection

Natural Selection -- its power compared with man's selection -- its power

on characters of trifling importance -- its power at all ages and on both

sexes -- Sexual Selection -- On the generality of intercrosses between

individuals of the same species -- Circumstances favourable and

unfavourable to Natural Selection, namely, intercrossing, isolation, number

of individuals -- Slow action -- Extinction caused by Natural Selection --

Divergence of Character, related to the diversity of inhabitants of any

small area, and to naturalisation -- Action of Natural Selection, through

Divergence of Character and Extinction, on the descendants from a common

parent -- Explains the Grouping of all organic beings.

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Chapter V

Laws of Variation

Effects of external conditions -- Use and disuse, combined with natural

selection; organs of flight and of vision -- Acclimatisation -- Correlation

of growth -- Compensation and economy of growth -- False correlations --

Multiple, rudimentary, and lowly organised structures variable -- Parts

developed in an unusual manner are highly variable: specific characters

more variable than generic: secondary sexual characters variable --

Species of the same genus vary in an analogous manner -- Reversions to

long-lost characters -- Summary.

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Chapter VI

Difficulties on Theory

Difficulties on the theory of descent with modification -- Transitions --

Absence or rarity of transitional varieties -- Transitions in habits of

life -- Diversified habits in the same species -- Species with habits

widely different from those of their allies -- Organs of extreme perfection

-- Means of transition -- Cases of difficulty -- Natura non facit saltum --

Organs of small importance -- Organs not in all cases absolutely perfect --

The law of Unity of Type and of the Conditions of Existence embraced by the

theory of Natural Selection.

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Chapter VII

Instinct

Instincts comparable with habits, but different in their origin --

Instincts graduated -- Aphides and ants -- Instincts variable -- Domestic

instincts, their origin -- Natural instincts of the cuckoo, ostrich, and

parasitic bees -- Slave-making ants -- Hive-bee, its cell-making instinct -

- Difficulties on the theory of the Natural Selection of instincts --

Neuter or sterile insects -- Summary.

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Chapter VIII

Hybridism

Distinction between the sterility of first crosses and of hybrids --

Sterility various in degree, not universal, affected by close

interbreeding, removed by domestication -- Laws governing the sterility of

hybrids -- Sterility not a special endowment, but incidental on other

differences -- Causes of the sterility of first crosses and of hybrids --

Parallelism between the effects of changed conditions of life and crossing

-- Fertility of varieties when crossed and of their mongrel offspring not

universal -- Hybrids and mongrels compared independently of their fertility

-- Summary.

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Chapter IX

On the Imperfection of the Geological Record

On the absence of intermediate varieties at the present day -- On the

nature of extinct intermediate varieties; on their number -- On the vast

lapse of time, as inferred from the rate of deposition and of denudation --

On the poorness of our palaeontological collections -- On the intermittence

of geological formations -- On the absence of intermediate varieties in any

one formation -- On the sudden appearance of groups of species -- On their

sudden appearance in the lowest known fossiliferous strata.

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Chapter X

On the Geological Succession of Organic Beings

On the slow and successive appearance of new species -- On their different

rates of change -- Species once lost do not reappear -- Groups of species

follow the same general rules in their appearance and disappearance as do

single species -- On Extinction -- On simultaneous changes in the forms of

life throughout the world -- On the affinities of extinct species to each

other and to living species -- On the state of development of ancient forms

-- On the succession of the same types within the same areas -- Summary of

preceding and present chapters.

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Chapter XI

Geographical Distribution

Present distribution cannot be accounted for by differences in physical

conditions -- Importance of barriers -- Affinity of the productions of the

same continent -- Centres of creation -- Means of dispersal, by changes of

climate and of the level of the land, and by occasional means -- Dispersal

during the Glacial period co-extensive with the world.

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Chapter XII

Geographical Distribution -- continued

Distribution of fresh-water productions -- On the inhabitants of oceanic

islands -- Absence of Batrachians and of terrestrial Mammals -- On the

relation of the inhabitants of islands to those of the nearest mainland --

On colonisation from the nearest source with subsequent modification --

Summary of the last and present chapters.

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Chapter XIII

Mutual Affinities of Organic Beings: Morphology: Embryology: Rudimentary Organs

Classification, groups subordinate to groups -- Natural system -- Rules and

difficulties in classification, explained on the theory of descent with

modification -- Classification of varieties -- Descent always used in

classification -- Analogical or adaptive characters -- Affinities, general,

complex and radiating -- Extinction separates and defines groups --

Morphology, between members of the same class, between parts of the same

individual -- Embryology, laws of, explained by variations not supervening

at an early age, and being inherited at a corresponding age -- Rudimentary

Organs; their origin explained -- Summary.

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Chapter XIV

Recapitulation and Conclusion

Recapitulation of the difficulties on the theory of Natural Selection --

Recapitulation of the general and special circumstances in its favour --

Causes of the general belief in the immutability of species -- How far the

theory of natural selection may be extended -- Effects of its adoption on

the study of Natural history -- Concluding remarks.

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Edited