RT I

Sec. i. On variation under domestication, and on the principles
of selection 1

Sec. ii. On variation in a state of nature and on the natural
means of selection 4

Sec. iii. On variation in instincts and other mental attributes 17

PART II

Sec.Sec. iv. and v. On the evidence from Geology. (The reasons for
combining the two sections are given in the Introduction) 22

Sec. vi. Geographical distribution 29

Sec. vii. Affinities and classification 35

Sec. viii. Unity of type in the great classes 38

Sec. ix. Abortive organs 45

Sec. x. Recapitulation and conclusion 48

ESSAY OF 1844

PART I

CHAPTER I 57-80

ON THE VARIATION OF ORGANIC BEINGS UNDER DOMESTICATION;
AND ON THE PRINCIPLES OF SELECTION.

Variation
On the hereditary tendency
Causes of Variation
On Selection
Crossing Breeds
Whether our domestic races have descended from one or more wild stocks
Limits to Variation in degree and kind
In what consists Domestication--Summary

CHAPTER II 81-111

ON THE VARIATION OF ORGANIC BEINGS IN A WILD STATE;
ON THE NATURAL MEANS OF SELECTION; AND ON THE
COMPARISON OF DOMESTIC RACES AND TRUE SPECIES.

Variation
Natural means of Selection
Differences between "Races" and "Species":-first, in their trueness
or variability
Difference between "Races" and "Species" in fertility when crossed
Causes of Sterility in Hybrids
Infertility from causes distinct from hybridisation
Points of Resemblance between "Races" and "Species"
External characters of Hybrids and Mongrels
Summary
Limits of Variation

CHAPTER III 112-132

ON THE VARIATION OF INSTINCTS AND OTHER MENTAL
ATTRIBUTES UNDER DOMESTICATION AND IN A STATE OF
NATURE; ON THE DIFFICULTIES IN THIS SUBJECT; AND
ON ANALOGOUS DIFFICULTIES WITH RESPECT TO CORPOREAL
STRUCTURES.

Variation of mental attributes under domestication
Hereditary habits compared with instincts
Variation in the mental attributes of wild animals