PREFACE TO SECOND EDITION. 



EXCEPT for the correction of a few misprints and verbal 

 inaccuracies, I have made no alterations in the text of this 

 edition. 



There are, however, two cases of unintentional mis- 

 representation to which I take this opportunity of drawing 

 attention, and for which I desire to offer an apology. On 

 p. 105 I imply that, on Mr. Eo^manes's hypothesis of 

 physiological selection or isolation, the differential fertility 

 must arise sporadically. This is not so ; and Mr. Eomanes 

 protests that this is not his theory. Logically, therefore, 

 the case should be stated thus : If these variations in 

 fertility arose sporadically in scattered individuals, there 

 would, in the absence of some co-operating mode of segre- 

 gation, be many chances to one against these scattered 

 individuals chancing to mate together ; but if these 

 varieties originated in a number of individuals coincidently, 

 this criticism falls to the ground ; and it only remains to 

 seek or state the cause of this coincident variation in these 

 numerous individuals. My discussion of the question was 

 therefore, and still remains, incomplete. I sincerely regret 

 that I have misrepresented the view of one who has 

 criticized my views in so helpful a spirit and has so 

 generously welcomed me as a fellow-worker in science. 



Secondly, in his kindly criticism and notice of my 

 work in Nature, vol. xliii., p. 340, Mr. A. K. Wallace 

 says, after quoting a passage on p. 206 of my book, " I do 

 not remember ever having used the term ' preferential 

 choice ' as applied to insects and the special colours or 



