46 COLOR AND SEX. 
In explanation of these remarkable differences of form 
and habit, we have first Darwin’s theory of “sexual se- 
lection.” This is based upon the ardor in love, the cour- 
age and rivalry of the males, and also upon the powers 
of perception, taste, and will of the female. 
' The spurs of the male, for example, are supposed 
to have been developed through the battles of the males. 
At first a mere knob, they were an advantage to the bird 
possessing them, enabling ‘himi to defeat his rivals. The 
successful male would be more likely to have offspring 
who would inherit the tendency of their father to have 
spurs, and thus, by selection, the unspurred cocks would — 
gradually be replaced by those better armed. This is 
known as the “ law of battle.” ' 
But the bright colors and gay plumes of the cock © 
have originated, under this theory, through the taste of 
the female, who, it is assumed, would be more likely to 
accept the attentions of a bird pleasing in her eye than 
one who was less strikingly adorned. This has been 
termed by Lloyd Morgan “ preferential mating.” 
Wallace has accepted the law of battle as an effective 
agent in producing certain characters, but considers it 
natural, rather than sewwal selection, and he denies the 
existence of any important evidence proving female selee- 
tion. He therefore attributes many secondary sexual 
characters to a surplus of vital energy, which, because of 
a bird’s perfect adaptation to the conditions of its exist- 
ence, can expend itself in the production of bright colors 
and ornamental plumes without injury to their owners. 
That is to say, Wallace ascribes to the action of natural 
selection any secondary sexual character which is of prac- 
tical use to the male in conflicts with a rival, but denies 
the female any part in the matter of pairing. Darwin, 
as I have said, attributes to the female an esthetic 
taste which renders the brilliant colors or display of the 
