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THE

ORIGIN OF SPECIES

BY MEANS OF NATURAL SELECTION

OR THE PRESERVATION OF FAVORED RACES IN
THE STRUGGLE FOR LIFE

BY

CHARLES DARWIN, M. A., LL. D., F. R. S.

WITH ADDITIONS AND CORRECTIONS
FROM SIXTH AND LAST ENGLISH EDITION

IN TWO VOLUMES

VOLUME II

NEW YORK

D. APPLETON AND COMPANY

1889

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CONTENTS OF VOL. II.

CHAPTER IX.

HYBRIDISM.

Distinction between the sterility of first crosses and of hybrids—
Sterility various in degree, not universal, affected by close
interbreeding, removed by domestication-Laws governing the
sterility of hybrids-Sterility not a special endowment, but
incidental on other differences, not accumulated by natural
selection-Causes of the sterility of first crosses and of hybrids
-Parallelism between the effects of changed conditions of
life and of crossing-Dimorphism and Trimorphism-Fertility
of varieties when crossed, and of their mongrel offspring not
universal-Hybrids and mongrels compared independently of
their fertility-Summary
Page 1

CHAPTER X.

ON THE IMPERFECTION OF THE GEOLOGICAL RECORD.

On the absence of intermediate varieties at the present day-On
the nature of extinct intermediate varieties; on their number
-On the lapse of time, as inferred from the rate of denudation
and of deposition-On the lapse of time as estimated by years
-On the poorness of our palæontological collections—On the
intermittence of geological formations-On the denudation of
granitic areas-On the absence of intermediate varieties in any
one formation-On the sudden appearance of groups of species
-On their sudden appearance in the lowest known fossiliferous
strata-Antiquity of the habitable earth
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