FIRST EDITION

LAST (SIXTH) EDITION

[It has not been thought necessary to make individual mention here of the very numerous Impressions of the above-mentioned Six Editions.] Reset (Sixth Edition), 2 vols.

Reprinted.

Reprinted.

Reprinted in 1 vol. (Popular Impression)

Reprinted.

Reprinted.

March 1888
March 1890

· January 1901

Reprinted (Sixth Edition, vol., Paper Covers). November 1901

December 1901

January 1902

February 1902

April 1902

August 1902

December 1902

March 1906

June 1906

December 1910

January 1920

AND PRINTE IN GREAT BRITAIN

Causes of Variability-Effects of Habit and the use or disuse of Parts-

Correlated Variation-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-Principles of Selection, anciently followed, their

Effects-Methodical and Unconscious Selection-Unknown Origin of our

Domestic Productions-Circumstances favourable to Man's power of

Selection

5

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

each country vary more frequently 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
30

CHAPTER III.

STRUGGLE FOR EXISTENCE.

Its bearing on natural selection-The term used in a wide sense-
e-Geometrical

ratio 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

Page 44

CHAPTER IV.

NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST.

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 the

results of 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-Advance

in organisation-Low forms preserved-Convergence of Character-

Indefinite multiplication of species-Summary

57

CHAPTER V.

LAWS OF VARIATION.

Effects of changed conditions-Use and disuse, combined with natural selection;

organs of flight and of vision-Acclimatisation-Correlated variation-

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

. 98

CHAPTER VI.

DIFFICULTIES OF THE THEORY.

Difficulties of the theory of descent with modification-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-Modes 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

Page 124

CHAPTER VII.

MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION.

Longevity-Modifications not necessarily simultaneous-Modifications ap-

parently of no direct service-Progressive development-Characters of

small functional importance, the most constant-Supposed incompetence

of natural selection to account for the incipient stages of useful structures

-Causes which interfere with the acquisition through natural selection

of useful structures-Gradations of structure with changed functions-

Widely different organs in members of the same class, developed from

one and the same source-Reasons for disbelieving in great and abrupt

modifications

156

CHAPTER VIII.

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, molothrus, ostrich, and

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

Changes of instinct and structure not necessarily simultaneous-Difficulties

of the theory of the Natural Selection of instincts-Neuter or sterile

insects-Summary
191

CHAPTER IX.

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, not accumulated

by natural selection-Causes of the sterility of first crosses and of hybrids

-Parallelism between the effects of changed conditions of life and of

crossing-Dimorphism and Trimorphism-Fertility of varieties when

crossed, and of their mongrel offspring not universal-Hybrids and

mongrels compared independently of their fertility-Summary 219

CHAPTER X.

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 lapse of

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

lapse of time as estimated by years-On the poorness of our palæonto-

logical collections-On the intermittence of geological formations-On

the denudation of granitic areas-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-

Antiquity of the habitable earth

CHAPTER XI.

ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS.

Page 247

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 chapter

CHAPTER XII.

GEOGRAPHICAL DISTRIBUTION.

272

Present distribution cannot be accounted for by differences in physical con-

ditions-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—Alternate Glacial periods in the north and south

290

CHAPTER XIII.

GEOGRAPHICAL DISTRIBUTION-continued.

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

-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 chapter

322