« AnteriorContinuar »
ADDITIONS AND CORRECTIONS, TO THE Sixth EDITION
VARIATION UNDER DOMESTICATION.
Causes of Variability-Effects of Habit and the use or disuse of
Parts Correlated Variation Inheritance Character of
VARIATION UNDER NATURE.
ranging, much diffused, and common species, vary most-
STRUGGLE FOR EXISTENCE.
Its bearing on natural selection—The term used in a wide sense
Geometrical ratio of increase-Rapid increase of naturalised
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
s–Sexual selection-On the generality
LAWS OF VARIATION.
Effects of changed conditions—Use and disuse, combined with
natural selection; organs of flight and of vision-Acclimatisa-
tion-Correlated variation-Compensation and economy of
.. Page 161
DIFFICULTIES OF THE THEORY.
Difficulties of the theory of descent with modification-Absence or
rarity of transitional varieties— Transitions in habits of life-
MISCELLANEOUS OBJECTIONS TO THE THEORY OF NATURAL
Longevity_Modifications not necessarily simultaneous—Modifica-
tions apparently of no direct service-Progressive development
Instincts comparable with habits, but different in their orizin-
Instincts graduated-Aphides and ants—Instincts variable