230 
SEXUAL selection: binds. 
ParI j 
As sexual selection depends on so fluctuating 
element as taste, we can understand how it is that w#l J ' 
in the same group of birds, with habits of life neafl' 
the same, there should exist white or nearly whk®’ 
as well as black, or nearly black species, — for instant’ 
white and black cockatoos, storks, ibises, swans, teO' 5 ’ 
and petrels. Piebald birds likewise sometimes occ ll | 
in the same groups, for instance, the black-neck®'' 
swan, certain terns, and the common magpie. I’k®' 
a strong contrast in colour is agreeable to birds, 
may conclude, by looking through any large collect^ 
of specimens or scries of coloured plates, for the se* 0 ’ 
frequently differ from each other in the male hav> 11 ' 
the pale parts of a purer white, and the various^ 
coloured dark parts of still darker tints than in t ' 1 ‘ 
female. 
It would even appear that mere novelty, or cha B » fc 
for the sake of change, has sometimes acted lik 0 *' 
charm on female birds, in the same manner as chang^ 
of fashion with us. The Duke of Argyll says, 66 — -and 
am glad to have the unusual satisfaction of foil 
lor even a short distance in his footsteps — “I am 
“ anc l more convinced that variety, mere variety, 
u be admitted to be an object and an aim in Nat 111 ®’ 
I wish the Duke had explained what he here mean 8 
Nature. Is it meant that the Creator of the uuiv 0 ^ 
ordained diversified results for His own satisfaction, m 0 
that ol man ? The former notion seems to me as 
wanting in due reverence as the latter in probabil 1 ^ 
Capriciousness of taste in the birds themselves app ea! g 
a more fitting explanation. For example; the ’ 
many other species are black. This fact supports the conjecture 
tliese conspicuous colours may aid the sexes in finding each other n 111 
the breeding-season. • 0 gg. 
50 ‘ The Journal of Travel,’ edited by A. Murray, vol. i. 1868, V- ' 
