by reason of their brighter plumage. Thus the duller coloured 
males died without offspring. On this assumption each 
succeeding generation would be, in some slight degree, 
brighter than the last, until the process of transformation 
ended in the glorified creatures we so admire to-day. 
It would be foreign to the purpose of this book to pursue 
this theme at length. Let it suffice to say that while the 
** Sexual Selection’’ theory still holds good, it has, so to 
speak, changed its complexion. And this largely owing to 
the accumulation of new facts. For the most important of 
these we are indebted to the singularly exact and laborious 
observations analysed, clarified, and interpreted with remark- 
able insight and sagacity of Mr. H. Eliot Howard, one of the 
keenest ornithologists of our time. He has set forth his 
case, and interpreted his facts with masterly skill, and there 
seems no escape from his conclusions. Briefly, he has shown 
that birds of quite sober coloration like the warblers, which 
formed the basis of his investigations, engage in displays 
quite as remarkable, and of precisely the same character as 
in birds of gaily coloured plumage. From this it is clear 
that this wing-play is not prompted by a more or less con- 
scious desire to display conspicuously coloured patches of 
colour, for of colour there is none save that of the general hue 
of varying shades of brown, as in the case of the grasshopper 
warbler, for example. Nor is the display, apart from colour, 
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