The subjects discussed in this volume are so connected that it is not a
little difficult to decide how they can be best arranged. I have determined
in the first part to give, under the heads of the various animals and
plants, a large body of facts, some of which may at first appear but little
related to our subject, and to devote the latter part to general
discussions. Whenever I have found it necessary to give numerous details,
in support of any proposition or conclusion, small type has been used.
(Here shown with [].) The reader will, I think, find this plan a
convenience, for, if he does not doubt the conclusion or care about the
details, he can easily pass them over; yet I may be permitted to say that
some of the discussions thus printed deserve attention, at least from the
professed naturalist.

It may be useful to those who have read nothing about Natural Selection, if
I here give a brief sketch of the whole subject and of its bearing on the
origin of species. (Introduction/1. To any one who has attentively read my
'Origin of Species' this Introduction will be superfluous. As I stated in
that work that I should soon publish the facts on which the conclusions
given in it were founded, I here beg permission to remark that the great
delay in publishing this first work has been caused by continued ill-
health.) This is the more desirable, as it is impossible in the present
work to avoid many allusions to questions which will be fully discussed in
future volumes.

From a remote period, in all parts of the world, man has subjected many
animals and plants to domestication or culture. Man has no power of
altering the absolute conditions of life; he cannot change the climate of
any country; he adds no new element to the soil; but he can remove an
animal or plant from one climate or soil to another, and give it food on