PREFACE.

ADDITIONS AND CORRECTIONS TO THE ESSAYS AS ORIGINALLY PUBLISHED.
VII.— A Theory of Birds’ Nests.
231, 232.	Introductory passages modified, with some omissions.
233	How modifications of organization would affect the form of the nest.
235	Illustration from the habits of children and savages.
235, 236.	Objection to term “hereditary habit” answered.
237	Passage rewritten, on more or less variable characters in relation to nidification.
248	On males choosing or rejecting females, and on the various modes in which colour may be acquired by female birds.