INTRODUCTION. 



'Origin of Species' (first edition, p. 199) I contented 

 myself by merely alluding to this belief. When I came 

 to apply this view to man, I found it indispensable to 

 treat the whole subject in full detail. 2 Consequently 

 the second part of the present work, treating of sexual 

 selection, 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 

 and the lower animals. My attention w T as 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 reserve my essay, which is 

 partially completed, for separate publication. 



2 Prof. Hiickel is the sole author who, since the publication of the 

 ' Origin,' has discussed, in his various works, in a very able manner 

 the subject of sexual selection, and has seen its full importance. 





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