On the Origin of Species
By
Charles Darwin
'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.
'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.
Down, Bromley, Kent,
October 1st, 1859.
,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
Introduction
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.
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.
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.
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.
,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.
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.
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.
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.
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.
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.
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.
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.
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.
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
By
Charles Darwin
'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.
'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.
Down, Bromley, Kent,
October 1st, 1859.
,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
Introduction
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.
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.
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.
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.
,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.
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.
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.
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.
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.
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.
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.
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.
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.
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
