Подробнее о книге
Моя библиотека
Книги в Google Play
Definition of species-Special creation-The early transmutationists—
Scientific opinion before Darwin-The problem before Darwin-The
change of opinion effected by Darwin-The Darwinian theory-Pro-
posed mode of treatment of the subject
Pages 1-13
CHAPTER II
THE STRUGGLE FOR EXISTENCE
Its importance-The struggle among plants-Among animals-Illustrative
cases-Succession of trees in forests of Denmark-The struggle for
existence on the Pampas-Increase of organisms in a geometrical
ratio-Examples of rapid increase of animals-Rapid increase and
wide spread of plants-Great fertility not essential to rapid increase
-Struggle between closely allied species most severe-The ethical
aspect of the struggle for existence 14-40
CHAPTER III
THE VARIABILITY OF SPECIES IN A STATE OF NATURE
Importance of variability-Popular ideas regarding it-Variability of the
lower animals-The variability of insects-Variation among lizards—
Variation among birds-Diagrams of bird-variation-Number of
varying individuals-Variation in the mammalia-Variation in
internal organs-Variations in the skull-Variations in the habits of
animals-The variability of plants-Species which vary little-Con-
cluding remarks
Pages 41-82
CHAPTER IV
VARIATION OF DOMESTICATED ANIMALS AND CULTIVATED
PLANTS
The facts of variation and artificial selection-Proofs of the generality of
variation-Variations of apples and melons-Variations of flowers-
Variations of domestic animals-Domestic pigeons-Acclimatisation
-Circumstances favourable to selection by man-Conditions favour-
able to variation-Concluding remarks
83-101
CHAPTER V
NATURAL SELECTION BY VARIATION AND SURVIVAL OF THE
FITTEST
Effect of struggle for existence under unchanged conditions-The effect
under change of conditions-Divergence of character-In insects—In
birds-In mammalia-Divergence leads to a maximum of life in each
area-Closely allied species inhabit distinct areas-Adaptation to
conditions at various periods of life-The continued existence of low
forms of life-Extinction of low types among the higher animals-
Circumstances favourable to the origin of new species-Probable
origin of the dippers-The importance of isolation-On the advance
of organisation by natural selection-Summary of the first five
chapters
102-125
CHAPTER VI
DIFFICULTIES AND OBJECTIONS
Difficulty as to smallness of variations-As to the right variations occur-
ring when required—The beginnings of important organs-The mam-
mary glands-The eyes of flatfish-Origin of the eye-Useless or
non-adaptive characters-Recent extension of the region of utility in
plants-The same in animals-Uses of tails-Of the horns of deer-
Of the scale-ornamentation of reptiles-Instability of non-adaptive
characters-Delboeuf's law-No "specific" character proved to be
useless-The swamping effects of intercrossing-Isolation as prevent-
ing intercrossing-Gulick on the effects of isolation-Cases in which
isolation is ineffective
Pages 126-151
CHAPTER VII
ON THE INFERTILITY OF CROSSES BETWEEN DISTINCT SPECIES
AND THE USUAL STERILITY OF THEIR HYBRID OFFSPRING
Statement of the problem-Extreme susceptibility of the reproductive
functions-Reciprocal crosses— Individual differences in respect to
cross-fertilisation-Dimorphism and trimorphism among plants-
Cases of the fertility of hybrids and of the infertility of mongrels
—The effects of close interbreeding-Mr. Huth's objections—Fertile
hybrids among animals-Fertility of hybrids among plants-Cases of
sterility of mongrels-Parallelism between crossing and change of
conditions-Remarks on the facts of hybridity-Sterility due to
changed conditions and usually correlated with other characters—
Correlation of colour with constitutional peculiarities-The isolation
of varieties by selective association-The influence of natural selection
upon sterility and fertility-Physiological selection-Summary and
concluding remarks 152-186
CHAPTER VIII
THE ORIGIN AND USES OF COLOUR IN ANIMALS
The Darwinian theory threw new light on organic colour-The problem to
be solved-The constancy of animal colour indicates utility-Colour
and environment—Arctic animals white-Exceptions prove the rule-
Desert, forest, nocturnal, and oceanic animals-General theories of
animal colour—Variable protective colouring—Mr. Poulton's experi-
ments-Special or local colour adaptations-Imitation of particular
objects-How they have been produced-Special protective colouring
of butterflies-Protective resemblance among marine animals-Pro-
tection by terrifying enemies-Alluring coloration-The coloration
of birds' eggs-Colour as a means of recognition-Summary of the
preceding exposition-Influence of locality or of climate on colour-
Concluding remarks
187-231
CHAPTER IX
WARNING COLORATION AND MIMICRY
The skunk as an example of warning coloration-Warning colours among
insects-Butterflies-Caterpillars-Mimicry-How mimicry has been
produced-Heliconida-Perfection of the imitation-Other cases of
mimicry among Lepidoptera-Mimicry among protected groups-Its
explanation-Extension of the principle-Mimicry in other orders of
insects-Mimicry among the vertebrata-Snakes-The rattlesnake and
the cobra-Mimicry among birds-Objections to the theory of mimicry
--Concluding remarks on warning colours and mimicry
Pages 232-267
CHAPTER X
COLOURS AND ORNAMENTS CHARACTERISTIC OF SEX
Sex colours in the mollusca and crustacea-In insects-In butterflies and
moths-Probable causes of these colours-Sexual selection as a
supposed cause-Sexual coloration of birds-Cause of dull colours of
female birds-Relation of sex colour to nesting habits-Sexual colours
of other vertebrates-Sexual selection by the struggles of males-
Sexual characters due to natural selection-Decorative plumage of
males and its effect on the females-Display of decorative plumage
by the males-A theory of animal coloration-The origin of accessory
plumes-Development of accessory plumes and their display-The
effect of female preference will be neutralised by natural selection—
General laws of animal coloration-Concluding remarks 268-300
CHAPTER XI
THE SPECIAL COLOURS OF PLANTS: THEIR ORIGIN
AND PURPOSE
The general colour relations of plants-Colours of fruits-The meaning of
nuts-Edible or attractive fruits-The colours of flowers-Modes of
securing cross-fertilisation-The interpretation of the facts-Summary
of additional facts bearing on insect fertilisation-Fertilisation of
flowers by birds-Self-fertilisation of flowers-Difficulties and con-
tradictions-Intercrossing not necessarily advantageous-Supposed
evil results of close interbreeding-How the struggle for existence
acts among flowers-Flowers the product of insect agency-Concluding
remarks on colour in nature Pages 301-337
CHAPTER XII
THE GEOGRAPHICAL DISTRIBUTION OF ORGANISMS
The facts to be explained-The conditions which have determined dis-
tribution-The permanence of oceans-Oceanic and continental areas
-Madagascar and New Zealand-The teachings of the thousand-
fathom line-The distribution of marsupials-The distribution of
tapirs-Powers of dispersal as illustrated by insular organisms-Birds
and insects at sea-Insects at great altitudes-The dispersal of plants
—Dispersal of seeds by the wind-Mineral matter carried by the wind
-Objections to the theory of wind-dispersal answered-Explanation
of north temperate plants in the southern hemisphere-No proof of
glaciation in the tropics-Lower temperature not needed to explain
the facts-Concluding remarks 338-374
CHAPTER XIII
THE GEOLOGICAL EVIDENCES OF EVOLUTION
What we may expect-The number of known species of extinct animals-
Causes of the imperfection of the geological record-Geological
evidences of evolution-Shells-Crocodiles-The rhinoceros tribe-
The pedigree of the horse tribe-Development of deer's horns-Brain
development-Local relations of fossil and living animals-Cause
of extinction of large animals-Indications of general progress in
plants and animals-The progressive development of plants—Possible
cause of sudden late appearance of exogens-Geological distribu-
tion of insects-Geological succession of vertebrata-Concluding
remarks
375-409