PREFACE TO THE SECOND EDITION. 
Ix 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 seem 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. 
Francis DARWIN. 
CAMBRIDGE, 
July, 1888. 
