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A NATURALIST'S VOYAGE ROUND THE WORLD; or, A

JOURNAL OF RESEARCHES into the NATURAL HISTORY and GEOLOGY of the
COUNTRIES visited during the Voyage of H. M. S. Beagle, under the Command of
Capt. Frrz-Ror, R. N. Post 8vo. 98.

MURRAY.

ON THE STRUCTURE AND DISTRIBUTION OF CORAL
REEFS.

SMITH, ELDER, & Co.

GEOLOGICAL OBSERVATIONS ON VOLCANIC ISLANDS.

SMITH, ELDER, & Co.

GEOLOGICAL OBSERVATIONS ON SOUTH AMERICA.

A MONOGRAPH OF THE CIRRIPEDIA.
Illustrations. 2 vols. 8vo.

SMITH, ELDER, & Co.

With numerous

RAY SOCIETY. HARDWICKE.

ON THE VARIOUS CONTRIVANCES BY WHICH BRITISH
AND FOREIGN ORCHIDS ARE FERTILISED BY INSECTS; and on the
GOOD EFFECTS of CROSSING. With Woodcuts. Post 8vo. 98.
MURRAY.

ON THE MOVEMENTS and HABITS of CLIMBING PLANTS.
With Woodcuts.
WILLIAMS & NORGATE.

Preparing for Publication.

DOMESTIC ANIMALS AND CULTIVATED PLANTS; or,
The PRINCIPLES of VARIATION, INHERITANCE, REVERSION, CROSSING, INTER-
BREEDING, and SELECTION, UNDER DOMESTICATION.

LONDON: PRINTED BY W. CLOWES AND SONS, STAMFORD STREET,
AND CHARING CROSS.

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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-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

7-45

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CHAPTER II.

VARIATION UNDER NATURE.

Doubtful species

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Wide-
Variability Individual differences
ranging, much-diffused, and common species vary most-Spe-
cies of the larger genera in each 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

46-69

CHAPTER III.

STRUGGLE FOR EXISTENCE.

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Its bearing on natural selection The term used in a wide sense
Geometrical ratio of increase - Rapid increase of naturalised
animals and plants- Nature of the checks to increase - Compe-
tition 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 be-
tween 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.

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Page 70-89

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 inter-
crosses between individuals of the same species-Circumstances
favourable and unfavourable to Natural Selection, namely, in-
tercrossing, isolation, number of individuals-Slow action -
Extinction caused by Natural Selection - Divergence of Cha-
racter, 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 —
Objections considered Indefinite multiplication of species-
Summary ..

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CHAPTER V.

LAWS OF VARIATION.

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90-156

Effects of external conditions - Use and disuse, combined with
natural selection; organs of flight and of vision Acclimatisa-
tion-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
. 157-198

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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-Modes of transition-Cases of difficulty —
Natura non facit saltum - Organs of small inportance - 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 199-247

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CHAPTER VII.

INSTINCT.

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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-Changes of instinct and structure not
necessarily simultaneous - Difficulties on the theory of the
Natural Selection of instincts Neuter or sterile insects.
Summary

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.. 248-291

CHAPTER VIII.

HYBRIDISM.

Distinction between the sterility of first crosses and of hybrids -
Sterility various in degree, not universal, affected by close inter-
breeding, 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..
292-338

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CHAPTER IX.

ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.

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On

On the absence of intermediate varieties at the present day
the nature of extinct intermediate varieties; on their number-
On the vast lapse of time, as inferred from the rate of deposi-
tion and of denudation On the poorness of our palæontological
collections - On the denudation of granitic areas - On the
intermittence of geological formations - On the absence of
intermediate varieties in any one formation

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On the sudden

appearance of groups of species-On their sudden appearance in
the lowest known fossiliferous strata..

Page 339-375

CHAPTER X.

ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS.

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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 appear-
ance 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..
376-414

CHAPTER XI.

GEOGRAPHICAL DISTRIBUTION.

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Present distribution cannot be accounted for by differences in phy-
sical conditions - Importance of barriers — Affinity of the pro-
ductions 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 ..

415-456

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