CONTENTS 
NATURAL SELECTION 
I. On the Law which has Regulated the Introduction op 
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 — Geographical 
Distribution of Organisms — Geological Distribution of the Forms of 
Life— High Organisation of very ancient Animals consistent with 
this Law — Objections to Forbes’s Theory of Polarity — Rudimentary 
Organs — Conclusion ..... Pages 3-19 
II. On the Tendency op Varieties to Depart Indefinitely 
prom the Original Type 
Introductory Note — Instability of Varieties supposed to prove the per- 
manent distinctness of Species — The Struggle for Existence — The 
Law of Population of Species — The Abundance or Rarity 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 Original Species — The Partial Reversion of Domesti- 
cated Varieties explained — Lamarck’s Hypothesis very different 
from that now advanced — Conclusion .... 20-33 
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 
