236 
SEXUAL SELECTION: BIRDS. 
Par! ‘ 
With the species, in which the sexes differ in colo tir ’ 
it is possible that at first there existed a tendency ^ 
transmit the successive variations equally to both seS 68 ’ 
and that the females were prevented from acquiring ^ 
bright colours of the males, on account of tlm danger 
which they would have been exposed during incubati^ 11 
Lut it would be, as lar as I can see, an extremely 
cult process to convert, by means of natural selection, oJ)( , 
form of transmission into another. On the other h a ' )L 
there would not be the least difficulty in rendering “ 
female (lull-coloured, the male being still kept brig 1 '*' 
coloured, by the selection of successive variations, "In 1 ( 
weie from the first limited in their transmission to 
same sex. Whether the females of many species b 9 ' 
actually been thus modified, must at present rein 91 ' 1 
doubtful. When, through the law of the equal 
mission of characters to both sexes, the females h» ve 
been rendered as conspicuously coloured as the m 9 ^’ 
their instincts have often been modified, and they 1‘W 
been led to build domed or concealed nests. 
In one small and curious class of cases the ebarac^ 
and habits of the two sexes have been completely t’ 9 " 5 
posed, for the females are larger, stronger, more 
ferous and brightly-coloured than their males, 
have, also, become so quarrelsome that they often fir 
together like the males of the most pugnacious 
It, as seems probable, they habitually drive away rlf!l 
females, and by the display of their bright colours 1 
other charms endeavour to attract the mates, we c 'g 
understand how it is that they have gradually been * eJ \ 
tiered, by means ol sexual selection and sexually-li® 1 ^ 
transmission, more beautiful than the males— the h ltte 
being left unmodified or only slightly modified. . 
Whenever the law of inheritance at correspond 111 ® 
ages prevails, but not that of sexually-limited tra* 
