.

Speaking of the Humming Birds, the Duke of Argyll says: "In the first
place, it is to be observed of the whole group, that there is no
connection which can be traced or conceived, between the splendour of
the humming birds and any function essential to their life. If there
were any such connection, that splendour could not be confined, as it
almost exclusively is, to only one sex. The female birds are, of course,
not placed at any disadvantage in the struggle for existence by their
more sombre colouring." And after describing the various ornaments of
these birds, he says: "Mere ornament and variety of form, and these for
their own sake, is the only principle or rule with reference to which
Creative Power seems to have worked in these wonderful and beautiful
birds.... A crest of topaz is no better in the struggle for existence
than a crest of sapphire. A frill ending in spangles of the emerald is
no better in the battle of life than a frill ending in spangles of the
ruby. A tail is not affected for the purposes of flight, whether its
marginal or its central feathers are decorated with white.... Mere
beauty and mere variety, for their own sake, are objects which we
ourselves seek when we can make the Forces of Nature subordinate to the
attainment of them. There seems to be no conceivable reason why we
should doubt or question, that these are ends and aims also in the forms
given to living organisms" ("Reign of Law," p. 248).

Here the statement that "no connection can be conceived between the
splendour of the humming birds and any function essential to their
life," is met by the fact, that Mr. Darwin has not only conceived but
has shown, both by observation and reasoning, how beauty of colour and
form may have a direct influence on the most important of all the
functions of life, that of reproduction. In the variations to which
birds are subject, any more brilliant colour than usual would be
attractive to the females, and would lead to the individuals so adorned
leaving more than the average number of offspring. Experiment and
observation have shown, that this kind of sexual selection does actually
take place; and the laws of inheritance would necessarily lead to the
further development of any individual peculiarity that was attractive,
and thus the splendour of the humming birds is directly connected with
their very existence. It is true that "a crest of topaz may be no better
than a crest of sapphire," but either of