INTRODUCTION. 
5 
Origin of Species’ (first edition, p. 199) I contented 
ln yself by merely alluding to this belief. When I came 
to a PI>ly this view to man, I found it indispensable to 
treat the whole subject iu full detail. 2 Consequently 
tire second part of the present work, treating of sexual 
election, has extended to an inordinate length, com- 
pared with the first part ; but this could not be 
avoided. 
I had intended adding to the present volumes an 
essay on the expression of the various emotions by man 
dl| d the lower animals. My attention was called to this 
object many years ago by Sir Charles Bell’s admirable 
work. This illustrious anatomist maintains that man 
ls endowed with certain muscles solely for the sake 
expressing his emotions. As this view is obviously 
°Pposed to the belief that man is descended from some 
°ther and lower form, it was necessary for me to consider 
!t - I likewise wished to ascertain how far the emotions 
dre expressed in the same manner by the different races 
°f man. But owing to the length of the present work, 
have thought it better to reserve my essay, which is 
Partially completed, for separate publication. 
< q ) r °e Hackel ia the sole author who, since the publication of the 
th ^ as discussed, in his various works, in a very able manner 
e subject of sexual selection, and has seen its full importance. 
