of which was published in 1896 at New York and London, and
the leading ideas of which were sketched by the author in a
pamphlet in 1894. I must leave, however, to literary critics
the task of discussing the points of contact, resemblance, or
divergence between these works and mine.

The different chapters of this book were published first in the
Nineteenth Century ( "Mutual Aid among Animals," in September
and November 1890; "Mutual Aid among Savages," in April
1891; "Mutual Aid among the Barbarians," in January 1892;
"Mutual Aid in the Mediæval City," in August and September
1894; and "Mutual Aid amongst Modern Men," in January
and June 1896). In bringing them out in a book form my first
intention was to embody in an Appendix the mass of materials,
as well as the discussion of several secondary points, which had
to be omitted in the review articles. It appeared, however,
that the Appendix would double the size of the book, and I was
compelled to abandon, or, at least, to postpone its publication.
The present Appendix includes the discussion of only a few
points which have been the matter of scientific controversy
during the last few years; and into the text I have introduced
only such matter as could be introduced without altering the
structure of the work.

I am glad of this opportunity for expressing to the editor of
the Nineteenth Century, Mr. James Knowles, my very best
thanks, both for the kind hospitality which he offered to these
papers in his review, as soon as he knew their general idea, and
the permission he kindly gave me to reprint them.

BROMLEY, KENT,
1902.

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