238 SEXUAL SELECTION : BIRDS. Part II. 



the upper exposed surface of the plumage has been thus 

 coloured in both sexes, whilst the lower surface m the 

 males alone has been variously ornamented through 

 sexual selection. Finally, from the facts given in these 

 four chapters, we may conclude that weapons for battle, 

 organs for producing sound, ornaments of many kinds, 

 bright and conspicuous colours, have generally been 

 acquired by the males through variation and sexual 

 selection, and have been transmitted in various ways 

 according to the several laws of inheritance — the fe- 

 males and the young being left comparatively but little 

 modified.^^ 



^^ I am greatly indebted to the kindness of Mr, Sclater for having 

 looked over these four chapters on birds, and the two following ones 

 on mammals. By this means I have been saved from making mistakes 

 about the names of the species, and from giving any facts which are 

 actually known to this distinguished naturalist to be erroneous. But 

 of course he is not at all answerable for the accuracy of the statements 

 quoted by me from various authorities. 



