Chap. XIV. 
GEADATION OF CHAKACTEKS. 
143 
the feather being held erect, in the position in which it 
is here drawn. Be- 
neath this thickened 
part there is on the 
surface of the ball an 
oblique almost pure- 
white mark, w^hich 
shades off downwards 
into a pale-leaden hue, 
and this into yellow- 
ish and brown tints, 
which insensibly be- 
come darker and dark- 
er towards the lower 
part of the ball. It 
is this shading which 
gives so admirably the 
effect of light shining 
on a convex surface. 
If one of the balls be 
examined, it will be 
seen that the lower 
part is of a browner 
tint and is indistinctly 
separated by a curved 
oblique line from the 
upper part, which is 
yellower and more leaden; this oblique line runs at 
right angles to the longer axis of the white patch of 
light, and indeed of all the shading ; but this difference 
in the tints, which cannot of course be shewn in the 
woodcut, does not in the least interfere with the perfect 
shading of the ball.^^ It should be particularly ob- 
Fig. 56. Part of Secondary wing-feather of Argus 
pheasant, shewing two, a and h, perfect ocelli. 
A, B, C, &c., dark stripes running obliquely down, 
each to an ocellus. 
[Much of the web on both sMes, especially to the 
left of the shaft, has been cut off.] 
When the Argus pheasant displays his wing-feathers like a great 
fan, those nearest to the body stand more upright than the outer ones, 
