First published in the "Journal of the Proceedings of the Linnæan Society," August, 1858. Reprinted without alteration of the text, except one or two grammatical emendations.
III.--MIMICRY AND OTHER PROTECTIVE RESEMBLANCES AMONG ANIMALS.
First published in the "Westminster Review," July, 1867. Reprinted with a few corrections and some important additions, among which I may especially mention Mr. Jenner Weir's observations and experiments on the colours of the caterpillars eaten or rejected by birds.
IV.--THE MALAYAN PAPILIONIDÆ, OR SWALLOW-TAILED BUTTERFLIES, AS ILLUSTRATIVE OF THE THEORY OF NATURAL SELECTION.
First published in the "Transactions of the Linnæan Society," Vol. XXV. (read March, 1864), under the title, "On the Phenomena of Variation and Geographical Distribution, as illustrated by the Papilionidæ of the Malayan Region."
The introductory part of this essay is now reprinted, omitting tables, references to plates, &c., with some additions, and several corrections. Owing to the publication of Dr. Felder's "Voyage of the Novara" (Lepidoptera) in the interval between the reading of my paper and its publication, several of my new species must have their names changed for those given to them by Dr. Felder, and this will explain the want of agreement in some cases between the names used in this volume and those of the original paper.
First published in the "Intellectual Observer," July, 1867. Reprinted with considerable emendations and additions.
VII.--A THEORY OF BIRDS' NESTS; SHOWING THE RELATION OF CERTAIN DIFFERENCES OF COLOUR IN BIRDS TO THEIR MODE OF NIDIFICATION.
First published in the "Journal of Travel and Natural History" (No. 2), 1868. Now reprinted with considerable emendations and additions, by which I have endeavoured more clearly to express, and more fully to illustrate, my meaning in those parts which have been misunderstood by my critics.
First published in the "Quarterly Journal of Science," October, 1867. Now reprinted with a few alterations and additions.
IX.--THE DEVELOPMENT OF HUMAN RACES UNDER THE LAW OF NATURAL SELECTION.
First published in the "Anthropological Review," May, 1864. Now reprinted with a few important alterations and additions. I had intended to have considerably extended this essay, but on attempting it I found that I should probably weaken the effect without adding much to the argument. I have therefore preferred to leave it as it was first written, with the exception of a few ill-considered passages which never fully expressed my meaning. As it now stands, I believe it contains the enunciation of an important truth.