PREFACE 



The present work consists mainly of reprints of the 

 more important articles I have contributed to reviews and 

 other periodicals during the thirty-five years from 1865 

 to 1899. 



I have ventured to call them " Studies," because the 

 larger part of them deal with problems in which I have 

 been specially interested, and to the comprehension and 

 solution of which I have devoted much time and thought. 

 Many of these problems are connected with the modern 

 theory of evolution, others with important geological and 

 physical theories, others again with educational, political, 

 or social questions. They are dealt with either in the 

 way of exposition or criticism, and in several cases they 

 contain novel views or fresh arguments, strengthening the 

 case in favour of some of the disputed theories. 



In order to make the subjects discussed more interest- 

 ing to the general reader, I have, wherever possible, in- 

 troduced copious illustrations, and this has led me in 

 many cases so to modify and enlarge the original article 

 as to render it a new piece of work. Those which did not 

 lend themselves to illustration have received a careful 

 revision. 



