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Authorized Edition. CONTENTS.

CHAPTER V.

LAWS OF VARIATION.

Effects of changed conditions—Use and disuse, combined with

natural selection; organs of flight and of vision-Acclimatisa-

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CHAPTER VIII.

INSTINCT.

Instincts comparable with habits, but different in their orizin-

Instincts graduated—Aphides and ants—Instincts variable
Domestic instincts, their origin-Natural instincts of the cuckou
Molothrus, ostrich, and parasitic bees—Slave-making ants-
Hive-bee, its cell-making instinct Changes of instinct and
structure not necessarily simultaneous—Difficulties of the
theory of the Natural Selection of instincts-Neuter or sterile
insects—Summary

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