ures the foundation of
another course, which was given in the Royal Institution, under the
title "Before and after Darwin." Here the course extended over three
years--namely from 1888 to 1890. The lectures for 1888 were devoted to
the history of biology from the earliest recorded times till the
publication of the "Origin of Species" in 1859; the lectures for 1889
dealt with the theory of organic evolution up to the date of Mr.
Darwin's death, in 1882; while those of the third year discussed the
further developments of this theory from that date till the close of the
course in 1890.

It is from these two courses--which resembled each other in comprising
between thirty and forty lectures, but differed largely in other
respects--that the present treatise has grown. Seeing, however, that it
has grown much beyond the bulk of the original lectures, I have thought
it desirable to publish the whole in the form of three separate works.
Of these the first--or that which deals with the purely historical side
of biological science--may be allowed to stand over for an indefinite
time. The second is the one which is now brought out and which, as its
sub-title signifies, is devoted to the general theory of organic
evolution as this was left by the stupendous labours of Darwin. As soon
as the translations shall have been completed, the third portion will
follow (probably in the Autumn season), under the sub-title,
"Post-Darwinian Questions."

As the present volume is thus intended to be merely a systematic
exposition of what may be termed the Darwinism of Darwin, and as on this
account it is likely to prove of more service to general readers than to
professed naturalists, I have been everywhere careful to avoid assuming
even the most elementary knowledge of natural science on the part of
those to whom the exposition is addressed. The case, however, will be
different as regards the next volume, where I shall have to deal with
the important questions touching Heredity, Utility, Isolation, &c.,
which have been raised since the death of Mr. Darwin, and which are now
being debated with such salutary vehemence by the best naturalists of
our time.

My obligations to the Senatus of the University of Edinburgh, and to the
Board of Management of the Royal Institution, have already been
virtually expressed; but I should like to take this opportunity of also
expressing my obligations to the students who attended the lectures in
the University