4 THE DESCENT OF MAN. 



subject in full detail.* Consequently, the second part of 

 the present work, treating of sexual selection, has extended 

 to an inordinate length, compared with the first part; but 

 this could not be avoided. 



I had intended adding to the present volume an essay on 

 the expression of the various emotions by man and the 

 lower animals. My attention was called to this subject 

 many years ago by Sir Charles Bell's admirable work. 

 This illustrious anatomist maintains that man is endowed 

 with certain muscles solely for the sake of expressing his 

 emotions. As this view is obviously opposed to the belief 

 that man is descended from some other and lower form, it 

 was necessary for me to consider it. I likewise wished to 

 ascertain how far the emotions are expressed in the same 

 manner by the different races of man. But owing to the 

 length of the present work, I have thought it better to re- 

 serve my essay for separate publication. 



* Prof. Hackel was the only author, who, at the time when this 

 work first appeared, had discussed the subject of sexual selection, 

 and had seen its full importance, since the publication of the 

 "Origin;" and this he did in a very able manner in his various 

 works. 



