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 oc- 

 casionally 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. 



CAMBUDaE, July, 1888. 



T 



