Vlll PREFACE. 



IX. THE DEVELOPMENT OF HUMAN RACES UNDER 

 THE LAW OF NATURAL SELECTION. 



First ' published in the "Anthropological Review," 

 May, 1864. Now reprinted with a few important alter- 

 ations and additions. I had intended to have consider- 

 ably extended this essay, but on attempting it I found 

 that I should probably weaken the effect without add- 

 ing much to the argument. I have therefore preferred 

 to leave it as it was first written, with the exception 

 of a few ill-considered passages which never fully ex- 

 pressed my meaning. As it now stands, I believe it 

 contains the enunciation of an important truth. 



X. THE LIMITS OF NATURAL SELECTION AS APPLIED 

 TO MAN. 



This is the further development of a few sentences 

 at the end of an article on " Geological Time and the 

 Origin of Species," which appeared in the " Quarterly 

 Review," for April, 1869. I have here ventured to 

 touch on a class of problems which are usually consi- 

 dered to be beyond the boundaries of science^ but 

 which, I believe, will one day be brought within her 

 domain. 



For the convenience of those who are acquainted 

 with any of my essays in their original form, I sub- 

 join references to the more important additions and 

 alterations now made to them. 



