834 THE STORY OF THE BIRDS. 
tive bird known, which had imperfect and yet devel- 
oping means of flight, had even its wing quills flossy 
near the base and air-resisting near the tips only. 
The modern flyers have theirs solid-vaned nearly 
throughout. 
Since air-tight vanes are useful to keep out rain 
and keep in warmth, and are yet found on the tips of 
nearly all body or contour feathers, it might appear 
that the barbules developed hooks for this purpose. 
But in degenerate birds, as the apteryx and others, 
as we have seen, where flight has ceased the plumage 
has become loose and flossy. Also, where Nature has 
provided against wind and water she has usually done 
it with plumous feathers and dense downs, as noticed 
in the aquatic and arctic birds. Still, there can be no 
doubt that this hooked condition of the external part 
of feathers adds to the comfort, and yet more to the 
prevention of friction of the air in flight. These 
hooks and barbules (and even the barbs) are further 
modified or entirely lost at other demands, such as 
touch, hearing, noiseless flight, water resisting, etc., 
but more especially in keeping with ornaments by 
shape and structure of plumage. 
Upon the bird’s outer wrap, as we have seen, Na- 
ture has wrought some of the most skillful of her 
handiwork, hinting in the garment’s frayings the story 
of the wearer, writing in hieroglyphs of color upon 
the surface something of its hopes and fears, and in 
the plainer blotchings spelling out its haunts and 
habits. 
So, likewise, in various stages of the suit’s acquisi- 
