28 o 
COLOUR IN NATURE 
CHAP. 
what resembling that seen in downy feathers, and like 
many downy feathers they have very little pigment. 
Among these long feathers are the so-called “ wires,” 
which are feathers with all the parts save the rachis 
suppressed. The yellow feathers have no barbules, 
and the barbs are smooth, dilated, and brightly coloured 
with lipochrome pigment. The same pigment and 
the same feather structure is found in the bright yellow 
feathers forming the crest. Round the base of the 
beak and extending over the throat there is a band 
of green metallic colour produced by very much 
shortened feathers, in which the barbules have under¬ 
gone the same modification as those of the metallic 
feathers of sun-birds. Speaking generally, we may 
say that this bird shows more tendency to develop 
additional plumes than any great brilliancy of colour, 
but when bright colours are developed, their develop¬ 
ment is associated with a tendency to suppression of 
the barbules, and to dilatation of the naked barbs. 
The king Paradise bird (Cicinnunts regins ), on the 
other hand, shows less tendency to develop additional 
tufts but much greater brilliancy of tint. The female 
is a dull grayish tint, with a speckled breast, the male 
is brilliant red on the back, with a metallic green 
band separating the red head from the pure white 
of the ventral surface. The tail contains two much 
elongated wires displaying a brilliant green colour at 
their curled tips. The red feathers are coloured by the 
peculiar pigment zoorubin, which is practically absent 
from the female. The feathers containing it have as 
usual naked barbs, which are smooth, dilated, and 
polished, so that as compared with the general 
contour-feathers of the preceding species they are 
