PREFACE TO THE SECOND EDITION.
In the present Edition I have not attempted to give a complete account of the progress of the subject since 1875. Nor have I called attention to those passages occurring occasionally throughout the book wherein the Author makes use of explanations, illustrations, or reference to authorities which seems to me not perfectly satisfactory. I have merely wished to indicate the more important points brought to light by recent research. The additions are in some cases placed in the text, but they are more commonly given as footnotes. They are, in all cases, indicated by means of square brackets.
Misprints, errors in numbers, &c., have been set right, and a few verbal corrections have been taken from Charles Darwin's copy of the First Edition. Otherwise the text remains unchanged.
- Cambridge, July, 1888.
