THE ORIGIN OF SPECIES

VOL. II

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

VOL. II

NEW YORK

D. APPLETON AND COMPANY

1898

General Library System
University of Wisconsin-Madison
728 State Street

Madison, WI 53706-1494
U.S.A.

Distinction between the sterility of first crosses and of hybrids-

Sterility various in degree, not universal, affected by close in-

terbreeding, 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 uni-

versal-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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