distinct have descended from a single parent-form.

In June, 1859, Professor Huxley gave a lecture before the Royal Institution on the "Persistent Types of Animal Life". Referring to such cases, he remarks, "It is difficult to comprehend the meaning of such facts as these, if we suppose that each species of animal and plant, or each great type of organisation, was formed and placed upon the surface of the globe at long intervals by a distinct act of creative power; and it is well to recollect that such an assumption is as unsupported by tradition or revelation as it is opposed to the general analogy of nature. If, on the other hand, we view "Persistent Types" in relation to that hypothesis which supposes the species living at any time to be the result of the gradual modification of pre-existing species, a hypothesis which, though unproven, and sadly damaged by some of its supporters, is yet the only one to which physiology lends any countenance; their existence would seem to show that the amount of modification which living beings have undergone during geological time is but very small in relation to the whole series of changes which they have suffered."

In December, 1859, Dr. Hooker published his "Introduction to the Australian Flora". In the first part of this great work he admits the truth of the descent and modification of species, and supports this doctrine by many original observations.

The first edition of this work was published on November 24, 1859, and the second edition on January 7, 1860.

CONTENTS

AN HISTORICAL SKETCH OF THE PROGRESS OF OPINION ON THE ORIGIN OF SPECIES

DETAILED CONTENTS.

ORIGIN OF SPECIES.

INTRODUCTION.


CHAPTER I.   VARIATION UNDER DOMESTICATION

CHAPTER II.   VARIATION UNDER NATURE

CHAPTER III.   STRUGGLE FOR EXISTENCE

CHAPTER IV.   NATURAL SELECTION; OR THE SURVIVAL OF THE FITTEST

CHAPTER V.   LAWS OF VARIATION

CHAPTER VI.   DIFFICULTIES OF THE THEORY

CHAPTER VII.   MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL SELECTION

CHAPTER VIII.   INSTINCT

CHAPTER IX.   HYBRIDISM

CHAPTER X.   ON THE IMPERFECTION OF THE GEOLOGICAL RECORD

CHAPTER XI.   ON THE GEOLOGICAL SUCCESSION OF ORGANIC BEINGS

CHAPTER XII.   GEOGRAPHICAL DISTRIBUTION

CHAPTER XIII.     GEOGRAPHICAL DISTRIBUTION—continued

CHAPTER XIV.   MUTUAL AFFINITIES OF ORGANIC BEINGS

CHAPTER XV.   RECAPITULATION AND CONCLUSION


GLOSSARY OF THE PRINCIPAL SCIENTIFIC TERMS USED IN THE PRESENT VOLUME.

INDEX.

DETAILED CONTENTS.

INTRODUCTION
CHAPTER I.
VARIATION UNDER DOMESTICATION.
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.
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.
CHAPTER III.
STRUGGLE FOR EXISTENCE.
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—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; 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