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CONTENTS.

I.—On the Law which has regulated the introduction of New

Species.

Geographical distribution dependent on Geologic Changes — A Law

deduced from well-known Geographical and Geological facts—The

form of a true system of Classification determined by this Law-—Geo-

graphical Distribution of Organisms—Geological Distribution of the
forms of Life—High Organization of very ancient Animals consistent
with this Law—Objections to Forbes' Theory of Polarity—Rudi-
mentary Organs—Conclusion Pp. 1—25

II.—On the Tendency of Varieties to depart indefinitely from the

Original Type.

Instability of Varieties supposed to prove the permanent distinctness of

Species—The Struggle for Existence—The Law of Population of

Species—The Abundance or Earity of a Species dependent upon its

more or less perfect Adaptation to the Conditions of Existence—

Useful Variations will tend to Increase, useless or hurtful Variations

to Diminish—Superior Varieties will ultimately extirpate the Ori-

ginal Species — The Partial Eeversion of Domesticated Varieties

explained — Lamarck's Hypothesis very different from that now

advanced—Conclusion Pp. 26—44

III.—Mimicry, and other Protective Resemblances among

Animals.

Test of true and false Theories—Importance of the Principle of Utility
—Popular Theories of Colour in Animals—Importance of Conceal-
ment as influencing Colour—Special modifications of Colour—Theory
of Protective Colouring—Objection that Colour as being dangerous
should not exist in Nature—Mimicry—Mimicry among Lepidoptera
—Lepidoptera mimicking other Insects—Mimicry among Beetles—
Beetles mimicking other Insects—Insects mimicking Species of other
Orders—Cases of Mimicry among the Vertebrate,—Mimicry among
Snakes—Mimicry among Birds—Mimicry among Mammals—Objec-
tions to Mr, Bates' Theory of Mimicry—Mimicry by Female Insects
only—Cause of the dull Colours of Female Birds—Use of the gaudy
Colours of many Caterpillars—Summary—General deductions as to
Colour in Nature—Conclusion Pp. 45—129

IV.—The Malayan Papilioniclce, or Swallow-tailed Butterflies,

as illustrative of the Theory of Natural Selection.

Special value of the Diurnal Lepidoptera for inquiries of this Nature—

Question of the rank of the Papilionidge—Distribution of the Papi-

lionidas—Definition of the word Species—Laws and Modes of Varia-

tion— Simple Variability—Polymorphism or Dimorphism — Local

form or variety—Co-existing Variety—Eace or Subspecies—Species

—Variation as specially influenced by Locality—Local Variation of

Size—Local Variation of Form—Local Variations of Colour—Ee-

marks on the facts of Local Variation—Mimicry — Concluding

Eemarks on Variation in Lepidoptera—Arrangement—Geographical

Distribution—Eemarkable peculiarities of the island of Celebes—

Concluding Eemarks . Pp. 130-^200

Y.—On Instinct in Man and Animals.

How Instinct may be best Studied—Definition of Instinct—Does Man

possess Instincts ?—How Indians travel through unknown and track-

less Forests Pp. 201—210

VI.—The Philosophy of Birds' Nests.

Instinct or Eeason in the Construction of Birds' Nests—Do Men build

by Eeason or by Imitation ?—-Why does each Bird build a peculiar

kind of Nest ?—How do young Birds learn to build their first Nest?

Do Birds sing by Instinct or by Imitation ?—Man's Works mainly

Imitative—Birds do Alter and Improve their Nests when altered con-

ditions require it—Conclusion . Pp. 211—230

VII.—A Theory of Birds' Nests; showing the relation of certain

differences of colour in female birds to their mode of nidifi-

cation.

Changed Conditions and persistent Habits as influencing Nidification—

Classification of Nests—Sexual differences of Colour in Birds—The

Law which connects the Colours of Female Birds with the mode of

Nidification—What the Facts Teach us—Colour more variable than
Structure or Habits, and therefore the Character which has generally

been modified—Exceptional cases confirmatory of the above Explana-

tion—Real or apparent exceptions to the Law stated at p. 240—

Various modes of Protection of Animals—Females of some groups

require and obtain more Protection than the Males—Conclusion

Pp. 231-263

VIII.—Creation by Laio.

Laws from which the Origin of Species may be deduced—Mr. Darwin's

Metaphors liable to Misconception—A case of Orchis-structure ex-

plained by Natural Selection—Adaptation brought about by General

Laws—Beauty in Nature—How new Forms are produced by Varia-

tion and Selection—The Objection that there are Limits to Variation

—Objection to the argument from Classification—The Times on

Natural Selection—Intermediate or generalized forms of Extinct

Animals an indication of Transmutation or Development—Conclu-

sion—A Demonstration of the Origin of Species 0 Pp. 264—301

IX.—The Development of Human Races under the Laiv of

Natural Selection.

Wide difference of Opinion as to Man's Origin—Outline of the Theory

of Natural Selection—Different effects of Natural Selection on

Animals and on Man—Influence of External Nature in the develop-

ment of the Human Mind—Extinction of Lower Races—The Origin

of the Races of Man—The Bearing of these views on the Antiquity

of Man—Their Bearing on the Dignity and Supremacy of Man—

Their Bearing on the future Development of Man—Summary—Con-

clusion , Pp. 302—331

X.—The Limits of Natural Selection as applied to Man,

What Natural Selection can Not do—The Brain of the Savage shown

to be Larger than he Needs it to be—Size of Brain an important

Element of Mental Power—Comparison of the Brains of Man and of

Anthropoid Apes—Range of intellectual power in Man—Intellect of

Savages and of Animals compared—The use of the Hairy Covering

of Mammalia—The Constant absence of Hair from certain parts of

Man's body a remarkable Phenomenon—Savage Man feels the want

of this Hairy Covering—Man's Naked Skin could not have been pro-

duced by Natural Selection—Feet and Hands of Man considered as
Difficulties on the Theory of Natural Selection—The Origin of Some

L

ON THE LAW WHICH HAS BEGULATED THE INTRODUCTION OF NEW SPECIES.*

Geographical Distribution dependent on Geologic
Changes.

Eveky naturalist who has directed his attention to the subject of the geographical distribution of animals and plants, must have been interested in the singular facts which it presents. Many of these facts are quite different from what would have been anticipated, and have hitherto been considered as highly curious, but quite inexplicable. None of the explanations attempted from the time of Linnseus are now considered at all satisfactory; none of them have given a cause sufficient to account for the facts known at the time, or comprehensive enough to include all the new facts which have since been, and are daily being added. Of late years, however, a great light has been thrown upon the subject by geological investigations, which have shown that the present state of the earth and of the organisms now

* Written at Sarawak in February, 1855, and published in the "Annals and Magazine of Natural History," September,

1855.

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