234 
SEXUAL SELECTION: BIBDS. 
Part* 
exhibit a marked preference or antipathy for certa 1 ® 
individual males. 
If it be admitted that the females prefer, or flI< 
unconsciously excited by the more beautiful males, d |£l 
the males would slowly but surely be rendered 
and more attractive through sexual selection. That 1 ' 
is this sex which has been chiefly modified vve may h 1 ^ 
from the fact that in almost every genus in which th® 
sexes differ, the males differ much more from each otk' 1 
than do the females ; this is well shewn in certain clo^' 
allied representative species in which the females 
hardly be distinguished, whilst the males are quite 
tinct. Birds in a state of nature offer individual diff el j 
ences which would amply suffice for the work of seS> u ‘ 
selection ; but we have seen that they occasionally f 6 ' 
sent more strongly-marked variations which recti*' 
frequently that they would immediately be fixed- 1 
they served to allure the female. The law’s of vari&ti o5) 
will have determined the nature of the initial cbai'g £v ' 
and largely influenced the final result. The g*"’ 1 ^ 
tions, which may be observed between the males ® 
allied species, indicate the nature of the steps whi^ 
have been passed through, and explain in the 111 ^ 
interesting manner certain characters, such as * \ 
indented ocelli of the tail-feathers of the peacock, a 11 , 
the wonderfully-shaded ocelli of the wing-feather^ 
the Argus pheasant. It is evident that the briU 1 '®? 
colours, top-knots, fine plumes, Ac., of many ^ , 
birds cannot have been acquired as a protect* 011 ’ 
indeed they sometimes lead to danger. That thjv 
are not due to the direct and definite action of * 
conditions of life, 
tb« 
we may feel assured, because ^ 
females have been exposed to the same conditions, ^ 
yet often differ from the males to an extreme deg 1 ^ 
Although it is probable that changed conditions act* 11 * 
